WO2017174093A2 - Procédés et bioréacteurs pour la digestion microbienne employant des biofilms immobilisés - Google Patents

Procédés et bioréacteurs pour la digestion microbienne employant des biofilms immobilisés Download PDF

Info

Publication number
WO2017174093A2
WO2017174093A2 PCT/DK2017/050110 DK2017050110W WO2017174093A2 WO 2017174093 A2 WO2017174093 A2 WO 2017174093A2 DK 2017050110 W DK2017050110 W DK 2017050110W WO 2017174093 A2 WO2017174093 A2 WO 2017174093A2
Authority
WO
WIPO (PCT)
Prior art keywords
biofilm
fad
flow
less
bioreactor
Prior art date
Application number
PCT/DK2017/050110
Other languages
English (en)
Other versions
WO2017174093A9 (fr
WO2017174093A3 (fr
Inventor
Bjarne Uller
Jorge Enrique Gonzalez LONDONO
Laurent LARDON
Niels Henriksen
Karl Björn RECHINGER
Original Assignee
Dong Energy Thermal Power A/S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dong Energy Thermal Power A/S filed Critical Dong Energy Thermal Power A/S
Publication of WO2017174093A2 publication Critical patent/WO2017174093A2/fr
Publication of WO2017174093A3 publication Critical patent/WO2017174093A3/fr
Publication of WO2017174093A9 publication Critical patent/WO2017174093A9/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M21/00—Bioreactors or fermenters specially adapted for specific uses
    • C12M21/04—Bioreactors or fermenters specially adapted for specific uses for producing gas, e.g. biogas
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/28—Anaerobic digestion processes
    • C02F3/2806—Anaerobic processes using solid supports for microorganisms
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M23/00—Constructional details, e.g. recesses, hinges
    • C12M23/34—Internal compartments or partitions
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M25/00—Means for supporting, enclosing or fixing the microorganisms, e.g. immunocoatings
    • C12M25/10—Hollow fibers or tubes
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M25/00—Means for supporting, enclosing or fixing the microorganisms, e.g. immunocoatings
    • C12M25/16—Particles; Beads; Granular material; Encapsulation
    • C12M25/18—Fixed or packed bed
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M27/00—Means for mixing, agitating or circulating fluids in the vessel
    • C12M27/18—Flow directing inserts
    • C12M27/20—Baffles; Ribs; Ribbons; Auger vanes
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M45/00—Means for pre-treatment of biological substances
    • C12M45/02—Means for pre-treatment of biological substances by mechanical forces; Stirring; Trituration; Comminuting
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M45/00—Means for pre-treatment of biological substances
    • C12M45/06—Means for pre-treatment of biological substances by chemical means or hydrolysis
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M45/00—Means for pre-treatment of biological substances
    • C12M45/09—Means for pre-treatment of biological substances by enzymatic treatment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/02—Biological treatment
    • C02F11/04—Anaerobic treatment; Production of methane by such processes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E50/00—Technologies for the production of fuel of non-fossil origin
    • Y02E50/30—Fuel from waste, e.g. synthetic alcohol or diesel

Definitions

  • the invention relates generally to methods and reactors for microbial digestion and/or reaction and specifically to methods and reactors comprising an insert comprising a biofilm immobilized on a carrier matrix.
  • the invention also relates to methods and reactors for anaerobic digestion and specifically to methods and reactors in which a methane-producing biofilm is immobilized on a carrier matrix having fixed orientation.
  • waste streams that require further biological processing to recover clean water content and "energy from waste.”
  • MSW municipal solid waste
  • wastes from abattoirs, restaurants, dairy processing, and tanneries these waste streams contain a high level of tota l solids, typically greater than 7% by weight.
  • these waste streams inevitably become acidic due to spontaneous fermentation by ubiquitous bacteria. It is clearly advantageous that these waste streams be processed on the site where they are produced.
  • C ST R continuously stirred tank reactors
  • PCT/E P201 5/072650 discloses methods, devices and inserts for reactors for microbial and anaerobic digestion.
  • this PCT-application relates to reactors comprising inserts for biofilms, such as methane-producing biofilms, immobilized on a carrier matrix.
  • C ST R systems the microbiological consortium that metabolizes feed streams to methane, carbon dioxide and ammonia, is free-floating in solution, typically in floes.
  • the critical methanogenic Archaea are slow-reproducing and highly sensitive to external conditions. This renders C ST R systems notoriously prone to the phenomenon of substrate inhibition, or volatile fatty acid (VFA) toxicity.
  • VFA volatile fatty acid
  • Archaea stop reproducing and enter a state of metabolic dormancy.
  • C ST R systems typically require elaborate process controls and long digester retention times, typically 15 days or longer. Acidic and high-solids waste streams have proved unmanageable in C ST R systems due to problems associated with VFA toxicity - bursts of overproduction or drops in pH to levels at which methanogens cease to metabolize gives rise to accumulation of VFA.
  • Acidic waste streams are especially troublesome in C ST R systems.
  • C ontrol of pH in anaerobic digestion is a critical problem with complex dependencies on feed stream properties and on the buffering capacity of the reactor liquid volume at any given moment. (F or review see Anderson and Yang 1 992).
  • Increasing organic load on the reactor i.e, processing a high solids feed at shorter retention time
  • T he inherent requirement for buffering capacity is further increased, where the feed stream is, itself, acidic.
  • the feedstock stream In order for pH in a C ST R reactor not to fall beneath 6.5, at which level most methanogens cease to metabolize, the feedstock stream must typically be subject to pH adjustment. By far the most inexpensive means for chemical pH adjustment is sodium hydroxide.
  • a conventional C ST R reactor cannot recover simply by dilution of the substrate, since this dilutes the productive microbial community as well. Recovery from toxic events in C ST R systems typically requires discarding the digester content and re- seeding with microbiological cultures, which in turn leads to commercially disastrous, long production stops.
  • exopolymeric substances produced by bacteria as well as a heterogeneous mixture of other biological macromolecules.
  • a typical biofilm in an anaerobic digestion system comprises an outer surface that acts as a diffusion barrier.
  • the film can vary in thickness from very thin, on the order of 200 um (see e.g.
  • Mahendran et al. 2012 to moderately "thick,” between 2-5 mm (see e.g. Hickey et al. 1991 ).
  • the relative proportion of methanogenic Archaea to bacteria in C ST R systems is typically between 10-25% (S ee e.g. Leclerc et al. 2004; and see
  • biofilm is effectively suspended in solution, i.e., free floating in the reactor tank.
  • These "suspended" fixed film systems include reactors in which the biofilm has formed itself within free standing granules or, alternatively, on “mobile” immobilization media.
  • G ranular sludge systems can be arranged in a variety of ways. F or example, sludge granules may be augered (see e.g. C hen et al. 2010) or allowed to float as a "sludge blanket" (see e.g. Mohan et al.2007) or compartmentalized (see e.g. J i et al.
  • baffles see e.g. Alkarimiah et al. 201 1
  • a hybrid sludge blanket having a filter on the upper layer to prevent outflow loss of granules (see e.g. Banu and Kaliappan 2007) or in some other configuration.
  • a wide variety of different biofilm immobilization media can be used which is then allowed to float freely in a reactor tank, for example, specialized polyethylene carriers with blades providing surface area (C hai et al. 2014), pieces of polyvinylchloride (PVC ) pipe (P radeep et al.2014), or latex beads (Wu et al. 2003).
  • the biofilm is formed on immobilization media which is employed in the reactor with random orientation in a stationary bed.
  • immobilization media such as synthetic nylon pads (Deshpande et al. 2012), nylon fibers (Meesap et al. 2012), corrugated plastic rings (Martin et al. 2010), silica beads (Michaud et al. 2005), polypropylene rings (Austermann-Haun et al. 1 994), or clay beads (Wildenauer and Winter 1 985), which are used in random orientation to form a packed bed.
  • the biofilm is formed on immobilization media which is employed in the reactor with non-random orientation to form a fixed bed through which fluid flow can be more carefully controlled.
  • These fixed orientation, fixed bed systems have been viewed as a means for extending the range of tolerance to higher suspended solids content in the feed stream relative to random bed systems.
  • clogging is simply a function of suspended solids content in the feed stream.
  • additional precipitation step such as, for example, electrocoagulation (see e.g. Deshpande et al. 201 2)
  • high total solids typically imparts higher suspended solids.
  • Random orientation fixed bed systems and granule systems typically provide extremely fast and effective processing of feed streams having lower content of chemical oxygen demand (C OD) ( ⁇ 30 g/L) or suspended solids ( ⁇ 3% w/w).
  • F ixed orientation fixed bed systems typically can tolerate a higher C OD content in the feed stream and maintain a higher organic load at some defined level of C OD removal (for example 70% or greater).
  • a second factor contributing to clogging in fixed film systems is the tendency of 5 these systems to experience "channelling" effects in fluid stream flows through and around the immobilization media or granules. These effects are particularly pronounced in granule and "suspended" carrier systems and also in random orientation fixed bed systems, where microscopic non-homogeneous flow patterns result in internal bypass flows and formation of dead volumes. But this tendency
  • C hannelling effects in fixed orientation fixed bed systems create a kind of feed -forward cascade of clogging: “C hannelling” results in regional accumulation of attached solids at particular locations in the flow pattern through the support media.
  • F low patterns may be referred to as flow path within the meaning of this
  • a third factor contributing to clogging in fixed film systems which is considered the most important factor in fixed bed systems (E scudie et al. 201 1 ), is the growth of the film itself and the gradual accumulation of suspended biomass in the form of floes or detached segments of biofilm. (S ee Rajeshwari et al. 2000; Lima et al.
  • S uspended solids notably including suspended biomass (such as or including detached biofilm segments and floes), are gently precipitated within sedimentation zones that exist beneath neighbouring chambers of a compartmentalized reactor.
  • Vertical flow paths ensure that precipitating particles will be directed into a sedimentation zone.
  • the avoidance of agitation in favour of gentle, backflow mixing ensures that suspended particles will indeed precipitate in the
  • a downward, low-shear plug flow which imparts minimal risk of channelling, is directed through a plurality of tubular immobilization carriers, contained within a single chamber of the reactor. This downward flow is then directed onward into a sedimentation zone situated beneath the carriers. There within the sedimentation zone, the vertical direction of flow is forced to change into an upward, low-shear plug flow through tubular immobilization carriers contained within a succeeding chamber. As the flow proceeds through other chambers of the compartmentalized reactor, the vertical direction is forced to change between each successive chamber, thereby achieving a gentle backflow mixing both within sedimentation zones situated beneath the immobilization carriers, as well as within head space regions situated above the carriers.
  • Flow velocity through the system is determined by the effluent recirculation rate, by the dimensions of the reactor tank and by the number and dimensions of individual compartments within the reactor.
  • a reactor of the invention can be fitted with means for periodic removal of undissolved solids from sedimentation zones.
  • High C OD content of the feed stream permits maintenance of extremely high biogas flows, provided that low hydraulic retention times (H RT) are maintained.
  • H RT hydraulic retention times
  • biogas bubbles rise to the head space of systems of the invention by travelling along the surface of the biofilm, presumably involving both coalescence and cavitation events. These are conditions that, at high gas production rates, should encourage detachment of biofilm segments but
  • Fast anaerobic digester and its abbreviation FAD preferably refers to a structure or element configured for or containing microfilm carrier(s).
  • An FAD may be a standalone unit in the sense that it receives fluid to be anaerobic digested through an inlet and delivers fluid having been exposed to anaerobic digestion through an outlet.
  • an FAD may be in the form of an insert, which is introduced, such as retro-fitted, into a tank reactor, such as a
  • C ST R continuously stirred tank reactor
  • the biofilm carriers may not carry a biofilm or carry a desired amount of biofilm, the biofilm may be provided during an aerobic digestion phase where the biofilm material re-produces itself, typically starting with deposition of precursors.
  • Biofilm carries can be supplied with biofilm attached, from another system, or without biofilm.
  • a contact phase with effluent from another system, or with the feedstock complemented or not with a suspended inoculum, will allow the biofilm to develop s pontaneously by attachment and growth of the micro-organisms present in the liquid
  • Biofilm development typically begins as soon as a liquid flow containing microorganisms has contact with the carriers. These processes can occur both aerobically and anaerobically. The microorganisms then develop furtherly the biofilm as soon these are able to perceive nutrients in the liquid, therefore they grow, multiply and excrete the substances that will favour the subsequent attachment of other microorganisms to the biofilm.
  • biofilm may be grown on the biofilm carrier ex situ from a structure defining the FAD and transferred to an in situ location with biofilm carried. It is also noted that the biofilm carrier can be placed in the digester already fully occupied by a biofilm. It is also noted that when the carrier does not carry a biofilm by the time of placement such biofilm can be formed by the introduction of aerobically or anaerobically microbes following the flow pattern through the carrier arrangement under defined operating conditions
  • a FAD may stabilise the C ST R process by releasing active biofilm microbes into the C ST R
  • P lug flow is preferably used as defined herein and preferably to indicate the theoretical flow situation of a uniform velocity profile with a flow velocity defined as volume flow [m3/sec] divided by the cross sectional area [m2] in question, such as of the biofilm carrier or carrier compartment in question, e.g. opening A2 or A3 in fig. 1 B.
  • the plug flow may also be use to describe a guided flow (typically through a pipe or a channel) where the flow is mostly directed in one direction, allowing a distribution of physical, chemical or biological properties along this direction.
  • Back-flow or cross flows are possible but considered as neglictible compared to the main flow.
  • the flow may often be laminar but turbulent flow can be within the scope.
  • Tubular structure is preferably used to mean a structure defining a tube; the cross section of the tube can be polygonal, circular, elliptical or other shapes.
  • the longitudinal extension of the tubular structure may be straight, such as having one or more straight sections or curved, such as comprising one or more curved sections.
  • Stirring means as used herein is preferably used to mean a structure, element or device configured for stirring or agitating a substance inside a tank reactor.
  • Stirring means may be embodied as a propeller, a whisker or the like.
  • scrappers are used and such scrappers may also function as stirring means.
  • stirring means may be embodied as fluidic stirring means by providing, by means of flow channels and pumps, flow patterns, such as jets and/or circulations.
  • Stirring is preferably referred to as the agitation of part of or the whole C STR digester content in order to keep a fraction of or all particulate and sedimentable material suspended and preferably homogenously distributed throughout the entire digester liquid volume.
  • Stirring also preferably means securing that a fractio of or all free floating active microbes is in good contact with (any) still unconverted substrate in the digester liquid matrix.
  • the volume of an FAD is compared to the total volume of a tank reactor.
  • the considered volume of the FAD is preferably the interior volume of the FAD when biofilm carriers are located in the FAD.
  • the volume of the FAD is the amount of liquid than can be contained in the FAD. It is noted that in case of and FAD in the form of an insert the volume considered is typically the volume of liquid that can be contained in the tubular structure.
  • the total volume of a tank reactor is typically the volume of liquid that can be contained in the tank reactor.
  • Digestate is preferably used to mean the material remaining after the anaerobic digestion of a biodegradable feedstock or substrate.
  • digestate may advantageously be separated by separation means, such as filters, sedimentation tanks or the like into “dewatered digestate” and "reject water”.
  • the digestate or dewatered digestate can be subjected to a processing step and be fed back into a fermenter (AD (aerobic as well as anaerobic digestion), FAD, C ST R, C ST R/FAD hybrid), or even back to a microbial process producing a
  • feedstock or "substrate”
  • biomass preferably means any biomass, such as waste, sewage, manure, wheat straw, corn stover, sugar cane bagasse, sweet sorghum bagasse, or empty fruit bunches.
  • waste preferably means any kind of waste having an organic content, such as municipal solid waste (MSW), industrial waste, animal waste or plant waste.
  • hydroothermal pre- treatment preferably refers to the use of water, either as hot liquid, vapor steam or pressurized steam comprising high temperature liquid or steam or both, to "cook” biomass, at temperatures of 120°C or higher, either with or without addition of acids or other chemicals.
  • anaerobic digestion preferably refers to microbial activity, such as but not limited to fermentation under controlled aeration conditions, e.g. in absence or very limited amount of oxygen gas in which methane gas and/or hydrogen is produced. Methane gas is produced to the extent that the concentration of metabolically generated dissolved methane in the
  • aqueous phase of the fermentation mixture within the "anaerobic digestion" is saturating at the conditions used and methane gas is emitted from the system.
  • the term "aerobic digestion” preferably refers to microbial fermentation conducted under aerated conditions.
  • the term “COD or Chemical Oxygen Demand” preferably means the amount of oxygen which is needed for the oxidation of all organic substances in water in g/L and hence is a measure for the organic content or energy of the feedstock or biomass.
  • the feature "fixed film, fixed orientation, fixed bed” is referenced. This feature may also be referred to as a "fixed film fixed filter", “fixed film, fixed orientation, fixed filter” and even “fixed film, fixed orientation, fixed carrier”.
  • the flow is essentially parallel to the biofilm carrier - which may also be called “filter” herein - and not e.g. perpendicular and/or across, as in conventional filter applications.
  • the terms “about”, “around” , and/or “ ⁇ ” can be used interchangeably, and mean variations generally accepted in the field, e.g. comprising analytical errors and the like. Commonly, “around” means variations of +/- 1 , 2, 2.5, or 5.0 % (w w), but “around” may also indicate variations of e.g. up to a factor 1 .1 , 1 .2, 1 .5 or even 2.0 (+/- 10, 20, 50 or 100%).
  • FAD-assisted C ST R or FAD/C ST R combi as used herein is preferably used to indicate a system comprising and FAD and an C ST R as disclosed herein.
  • the FAD and the C ST R are arranged at least during operation so that at least a fraction of the digestate produced by the FAD is fed into the C ST R .
  • F urhter, the C ST R and the FAD are preferably fed with substrate during operation, e.g. during operation, the C ST R receives digestate and substrate (see also E xample 1 1 presented herein)
  • the FAD may be fitted in the C ST R tank or tank reactor in general.
  • biofilm carrier suitable for biofilm growth upon exposure to a flow of fluid containing biofilm precursors, the biofilm carrier comprising a three dimensional structure having at least one surface comprising cavities and protrusions thereby providing a rough surface.
  • Biofilm carrier may be referred to as biofilm support, biofilm matrix immobilizer or carrier matrix.
  • the protrusions may be extending out of the at least one surface between 0.1 and 10 mm.
  • the cavities or indentations may be in the area between 0.1 and 5 mm underneath the at least one surface.
  • the at least one surface is a rough surface is preferably being a rough surface, i.e. a surface that is not smooth.
  • the at least one surface may have a rough surface area (R a ) (as ordinary defined) between 0.1 and 10 mm, such as between 1 and 9 mm, for example between 2 and 8 mm.
  • R a may be between 3 and 6 mm.
  • the at least one surface may have a minimum valley depth R v between 0.5 and 1 .5 mm, such as 1 mm.
  • the at least one surface may have a minimum peak depth R p (as ordinary defined) between 1 and 2 mm, such as 2 mm.
  • the specific surface roughness has the advantage of allowing regrowth of the biofilm that has been at least partially washed out. During operation, it may occur that biofilm segments or floes detach from the biofilm carrier. Regrowth of biofilm may not be straightforward as the at least one surface is exposed to continuous fluid flow, thus not allowing for optimal regrowth condition.
  • the presence on the surface of elements, such as cavities or protrusions that are less exposed to fluid flow has thus the advantage of allowing for biofilm regrowth. Indeed, biofilm regrowth may start within the elements that are less exposed to the fluid flow.
  • the specific surface roughness has also the advantage of increasing the surface area available for biofilm growth and thus increasing the surface available for biofilm digestion of the feedstock introduced in contact with the biofilm carrier.
  • the three dimensional structure comprises openings, such as holes throughout the at least one surface.
  • the three dimensional structure may be a tubular porous three dimensional structure.
  • the porous may be open porous, i.e. a porous having at least an open end.
  • the three dimensional structure is or comprises a threaded structure.
  • the three dimensional structure is or comprises an open threaded structure.
  • a three dimensional open threaded structure may be made of two or more filaments twisted and attached together.
  • the advantage of having three dimensional structure comprising openings, whether these are open porous, throughout holes or an open threaded structure, is that the contact with the fluid flow may occur from both sides of the three dimensional structure where the flow of the fluid may have different
  • fluid flow may have different speed, different quality, e.g. different biogas producing potential, different temperature, just to name some. These different characteristics may allow preferential biofilm growth starting from one specific side of the three dimensional structure.
  • a first side of three dimensional structure may be exposed to a fluid flow having a higher speed than the one on a second side.
  • biofilm growth on the first side may not occur while biofilm growth on the second side may occur, eventually extending towards the first side through the opening.
  • a three dimensional structure comprising openings allows for faster regrowth of biofilm in case of partial or total detachment of the biofilm from the biofilm carrier.
  • the biofilm carrier comprises a biofilm.
  • the biofilm may be a biofilm comprising one or more different microorganisms adapted to aerobic or anaerobic digestion/fermentation
  • This embodiment has the advantage that biofilms grown on the biofilm carrier may be thus transported away from the growth environment, such as a tank reactor, and located in other apparatus, reactor or inserts for modifying reactors so as to be used for producing gas or other products.
  • a biofilm carrier actually carrying the biofilm may be treated so as to maintain its characteristics during transport, e. g. may be thermally treated, such as eventually frozen or protected, such as coated with a protective layer.
  • Biofilm carriers comprising the biofilm may be very robust i.e. may be transported as such, without e.g. the need of a thermal treatment, without a protective layer and/or protective or controlled atmosphere.
  • the invention in a second aspect, relates to an insert an insert, said insert comprising
  • the insert is suitable for modifying a tank reactor.
  • the insert has the advantage that when inserted into a tank reactor and when the tank reactor is in operation, the insert allows for restraining and directing the flow of a fluid with a very low level of maintenance as no or only a few mechanical moving parts are present and the one or more baffles are already fixed in the desired position without needing further adjustments.
  • a further advantage may be that energy usage or electrical consumption is minimized though the use of the insert.
  • An even further advantage of the insert is that it is able to restrain and direct a flow of fluid through the system avoiding clogging.
  • the insert defines open
  • This specific positioning in a reactor of the insert may ensure a desired vertical zigzag flow, alternating upwardly vertical flow and downwardly vertical flow of a fluid passing through the insert.
  • the one or more inserts are removably attached, i.e. attached in a way that allows for removal, to the continuously closed side wall.
  • the continuous closed side wall is an element of the insert and not of the tank reactor in which the insert may be inserted. In some embodiments, the continuous closed side wall is a curved wall.
  • curved continuous closed side wall has the advantage that the insert can be easily adapted to be inserted in most of the tank reactor currently available, which have at least one curved wall.
  • the disposition of underflow and overflow apertures is such that it forces a fluid to flow from an underflow aperture of open compartment M upwardly towards an overflow aperture of subsequent open compartment M+1 and subsequently downwardly towards an underflow aperture of a subsequent open compartment M+2, wherein M is a number higher than 1 .
  • compartments defines one or more sections of the insert.
  • a cylindrica l insert may comprises 4 quarter- cylinder sections having substantially equivalent cross sectional area and having a plurality of compartments defined by a plurality of baffles.
  • An outer section may comprise a curved outer wall that defines together with the baffles trapezoidal open compartments having one curved surface formed by the inner surface of the curved outer wall and another curved surface formed by the outer surface of a curved inner wall of an inner section. This configuration allows for optima l fitting of the insert in currently available reaction tanks.
  • the one or more sections may thus be external, i. e.
  • the one or more baffles and/or the continuous closed side wall are/is made from a corrosion resistant and liquid impermeable material.
  • the insert according to the second aspect of the invention further comprises means for supporting biofilms located in the at least two open compartments.
  • means for supporting biofilms may be biofilm supports, biofilm carriers or other means for immobilizing biofilms on a substrate.
  • the means for supporting biofilms are a plurality of biofilm carriers according to the first aspect of the invention.
  • the insert according to the second aspect of the invention define a preferential vertical path along and inside the biofilm carriers, thereby when inserted into a tank reactor and when the tank reactor is in operation with a fluid flow substantially parallel to the biofilm formation. This has the main advantage of avoiding clogging.
  • the invention relates to a bioreactor comprising: a bioreactor system comprising one or more FADs and one or more C ST Rs,
  • a tank reactor having one or more side walls and a bottom wall having an internal surface thereby defining a reactor volume and the tank reactor further comprising an inlet into and an outlet out from the reactor volume;
  • the FADs each comprising: - an outer tubular structure (A1 ) having a longitudinal extension (L), being made from a fluidic non-penetrable material and having an opening (A2, A3) at each end of the outer tubular structure so as define a flow passage inside the outer tubular structure extending between said openings, and - one or more fluid penetrable biofilm carriers (A4) arranged inside said outer tubular structure (A1 )
  • the bioreactor system according to the third aspect of the invention comprises the insert according to second aspect of the invention.
  • the one or more side walls of the container are the continuous closed side wall of a n insert according to the s econd aspect of the invention.
  • the bioreactor system further comprises means for forcing, when in operation, a fluid to flow downwardly or upwardly through the inserts in a preferential path.
  • a preferential path may be a preferential direction and orientation induced by means present along or across the flow.
  • a preferential flow path may be characterized by laminar flow, turbulent flow or by a combination of the two.
  • F or example means for forcing the fluid may be means for supporting biofilms such as biofilm supports, biofilm carriers or other means for immobilizing biofilms on a substrate which may influence the flow of a fluid.
  • means for forcing the fluid may be tubular biofil m immobilization carriers or tubular channels defining a path, e.g. inside the carrier or channel, which is preferred to another path, e.g. outside the carrier or channel.
  • the means for forcing a fluid to flow are the biofilm carriers according to the first aspect of the invention.
  • "forcing a fluid" refers to imposing a direction/path of fluid. In this embodiment, the preferential path is thus the one inside the hollow biofilm carrier.
  • a preferential path does not exclude that fluid flows through other paths.
  • the biofilm carriers are present the flow substantially flow throughout the carriers, i.e. more than 80% such as 85%, 90%, 95% or 99% of the total flow of the fluid flowing along the preferential path through the carriers.
  • the preferential vertical path along and inside the biofilm carriers do not clogg as the fluid flow is substantially parallel to the biofilm location, formation or
  • the bioreactor system further comprises means for promoting, such as continuously promoting, removal of precipitate, such as biomass or sediment, deposited or located on the internal surface of the bottom wall of the container.
  • the means for promoting removal of precipitate may be one or more rotating means, such as one or more rotating scrapers.
  • the invention in another aspect relates to a one or more rotating means, such as one or more rotating scrapers suitable for being used in a C ST R .
  • a rotating scraper may have a scraping edge and a top edge opposite to the scraping edge.
  • each of the one or more rotating scrapers has a scraping edge and a top edge opposite to the scraping edge.
  • the rotating scrapers When not in motion, the rotating scrapers lay in a positon that reduces or avoids short circuiting flow between neighbouring sections.
  • the one or more rotating scrapers when not in motion, lay in a positon that reduces or avoids short circuiting flow between neighbouring sections.
  • each rotating scrapers may be located
  • each of the one or more rotating scrapers is located underneath a full baffle delimiting a section.
  • An opportune gap between the edge of each rotating scraper and the edge of the baffle ensures for correct rotation as well as for reducing and/or avoiding cross- flow between sections.
  • a rotating scraper rotates clockwise or counter clockwise from its resting position, e.g. underneath a full baffle, to a second resting position, e.g. underneath a second full baffle.
  • a rotating scraper rotates clockwise or counter clockwise from its resting position, e.g. underneath a full baffle, to a second resting position, e.g. underneath a second full baffle.
  • one rotation provides scraping of the internal surface of the bottom wall of an entire section.
  • the one or more rotating scrapers are adapted to rotate clockwise or counter clockwise from a resting position underneath a first full baffle, to a second resting position underneath a second full baffle, thereby, one rotation provides scraping of the internal surface of said bottom wall of an entire s ection.
  • rotating scrapers may be located underneath low baffles and or high baffles, for example underneath each low and high baffle.
  • the one or more rotating scrapers are located underneath low baffles or high baffles.
  • the rotating scrapers provide a fluid tight seal between the bottom edge of the full baffles and the top edge of the rotating scrapers.
  • the one or more rotating scrapers provide a fluid tight seal between a bottom edge of full baffles and the top edge of said one or more rotating scrapers.
  • Fizid tight is herein defined as a seal that avoids or reduces at least by 50%, such as between 45% and 0.1 %, such as between 40% and 1 %, such as between 35% and 5%, such as between 30% and 10%, for example 25% the lateral flow between quarter sections of the reactor.
  • a fluid tight seal is thus a seal that ensures that cross-flow between compartments or sections and the static zones is lower than the desired value.
  • a desired value for optimal operation of the bioreactor may be lower than 50, such as between 50 and 40, or lower than 30, such as between 30 and 20, or lower than 20, such as between 20 and 10, or lower than 1 0 such as 7, 5, 1 , such as between 1 and 0.1 % of the flow through the correspondent overflow and underflow aperture.
  • the container comprises a bottom chamber defined or located between the internal surface of the bottom wall and a lowest level or lowest part of the insert according to the second aspect of the invention.
  • the bottom chamber may comprise the means for promoting removal of precipitate according to other embodiments of the invention.
  • the means for promoting removal of precipitate are adapted to define, when not in operation, static zones within the bottom chamber wherein cross-flow between compartments or sections and the static zones is lower than a desired value.
  • the static zones become mixing zones wherein cross-flow between compartments or sections and the static zones is higher than the desired value.
  • a desired value for optimal operation of the bioreactor may be lower than 50, such as between 50 and 40, or lower than 30, such as between 30 and 20, or lower than 20, such as between 20 and 10, or lower than 10 such as 7, 5, 1 , such as between 1 and 0.1 % of the flow through the correspondent overflow and underflow aperture.
  • the means for promoting removal of precipitate may be adapted to reduce the cross-flow as indicated above to less than 10% of the flow through the correspondent overflow and underflow aperture having the effect of achieving high gas production and low retention time.
  • the width, or size or diameter of the insert is substantially equal to, e. g. between 0 and 5% smaller than, a width or size or diameter of the container.
  • the insert has to fit inside the container. Different sizes, widths and diameters are possible so as to comply with this requirement depending on the design of the bioreactor.
  • the lowest level or part of the insert is located at a desired distance from the internal surface of the bottom wall. The desired distance is the distance allowing for reducing or avoiding short circuiting flow between neighbouring sections. The desired distance may be defined by the height of the rotating scraper, eventually allowing for a gap between the lowest level of the insert and the top edge of the rotating scraper.
  • the bioreactor further comprises means for keeping the insert at the desired distance from the internal surface of the bottom wall.
  • the means for keeping the insert at the desired distance may be a plurality of protrusions located on the one or more side walls of the container.
  • the means for keeping the insert at the desired distance from the internal surface of the bottom wall are a curvature of the bottom wall.
  • the curvature may gradually reduce the width, size or diameter of the container, wherein the width, size or diameter is defined by the one or more side walls of the container.
  • the insert may thus be held, raised or standing on the curvature of the bottom wall of the reactor.
  • bioreactor does not have a bottom wall that is curved
  • other means for keeping the insert at the desired distance from the internal surface of the bottom wall may be used according to the design of the bioreactor.
  • the open edges are displaced in respect to each other defining a plurality of underflow and overflow apertures, whereby, when the bioreactor is in operation, the fluid flows from an underflow aperture of a first compartment upwardly towards an overflow aperture of a second subsequent compartment and downwardly towards an underflow aperture of a third
  • the means for forcing a fluid to flow when the bioreactor is in operation, define a preferential flow path upwardly towards an overflow aperture or downwardly towards an underflow aperture of subsequent compa rtments.
  • a cross -flow in between not subsequent compartments is lower than a desired value.
  • a desired value may be lower than 50, such as between 50 and 40, or lower than 30, such as between 30 and 20, or lower than 20, such as between 20 and 10, or lower than 10 such as 7, 5, 1 , such as between 1 and 0.1 % of the flow through the correspondent overflow and underflow a perture.
  • S ubsequent compartments may also be neighbouring compartments that do not have favourite flow through overflow and underflow aperture in between each other.
  • a desire value may be lower than 50, such as between 50 and 40, or lower than 30, such as between 30 and 20, or lower than 20, such as between 20 and 10, or lower than 10 such as 7, 5, 1 , such as between 1 and 0.1 % of the flow through the overflow and underflow aperture of subsequent compartments having overflow and underflow aperture in between each other.
  • the bioreactor further comprises means for recirculating a fluid within each of the at least two open compartments.
  • the bioreactor further comprises means for recirculating a fluid in between the at least two open compartments. In some embodiments, the bioreactor further comprises means for recirculating a fluid within each section. In some further embodiments, the bioreactor further comprises means for recirculating a fluid in between sections.
  • the means for recirculating a fluid are one or more recirculation pumps.
  • the one or more recirculation pumps are in an amount equal to the amount of sections of the insert.
  • the one or more recirculation pumps are in an amount at least equal to the amount of sections of the insert.
  • the one or more recirculation pumps are in an amount equal to the amount of compartments of the insert divided by two.
  • the number of recirculation pumps may be more than the number of
  • the bioreactor may be designed so as to be flexible in respect to the change of the recirculation pattern and thus of the configuration of the pumps.
  • one single pump may be used for recirculation of two or more compartments, therefore in some embodiments the pumps may be also less than the amount of compartments.
  • the container is a cylindrical tank reactor.
  • the container may also have different geometries, for example the reactor may have a parallelepipedal, cubic or spherical geometry.
  • the invention relates in a fourth aspect to a bioreactor system for Biphase Fast Anearobic Digestion, the system comprising
  • a tank reactor having one or more side walls and a bottom wall having an internal surface thereby defining a reactor volume the tank reactor further comprising an inlet into and an outlet out from the reactor volume, - a break-up device being in fluid communication with the reactor volume of the tank reactor and being adapted to break-up solid material into smaller elements;
  • the bioreactor system further comprising one or more FADs comprising
  • one of the openings of a FAD is in fluid communication with the reactor volume.
  • the invention relates in a fifth aspect to a system for processing sludge, such as digestate, the system comprising:
  • a processing device configured for receiving the extracted sludge
  • the one or more fluid penetrable biofilm carriers (A4) may have a ratio of active surface to volume of fluid penetrable biofilm carriers of:
  • the active surface is preferably considered to be the wetted area of the fluid penetrable biofilm carriers, e.g. all the surface of the fluid penetrable biofilm carrier, typically evaluated before a biofilm is formed on the surface.
  • the volume of fluid penetrable biofilm carrier is preferably considered to be the interior volume of the fluid penetrable biofilms carriers.
  • the invention relates in a sixth aspect to a method of operating a bioreactor, the 20 bioreactor according to third aspect of the invention, the method comprising:
  • the digestions may be aerobic or anaerobic.
  • the fluid containing biofilm precursors is a feedstock having a C OD at least 30.0 gr/L.
  • the feedstock may have a C OD higher than 30.0 gr/L. In some further embodiments, the feedstock may have a C OD lower than 30.0 30 gr/L.
  • the feedstocks may also have lower C OD concentration than 30.0 gr/L.
  • the biofilm develops from the bacteria present in the inoculum and also from those in the feedstock, which can be of lower and higher C OD than here stated.
  • the feedstock may be waste water, e.g. having 0,5-10 g C OD/L, or manures having 1 - 100 g/C OD/L.
  • the feedstock may also be, for example, waste water with distillery vinasse, liquefied organic components of municipal solid waste (MSW), and wastes from abattoirs, restaurants, dairy processing, and tanneries. These waste streams contain a high level of total solids, typically greater than 7% by weight.
  • MSW municipal solid waste
  • any feedstock suitable for aerobic or anaerobic digestion/fermentation is believed to be suitable to be processed in a bioreactor as disclosed herein.
  • the conducting digestion of the fluid occurs with a hydraulic retention time of 120 hours or less while maintaining a flow velocity of at least 0.0002 m/s and a gas production rate of at least 5.0 Lgas/Ldigester/day
  • Hydraulic retention time may be between a period of 91 hours and a period of 52 days as shown in the examples.
  • F or example may be hydraulic retention time between 1 60 and 72 hours would also be possible as shown in example 7.
  • Gas production rate may be between 5.0 Lgas/Ldigester/day and 20.0
  • Lgas/Ldigester/day such as between 5.0 Lgas/Ldigester/day and 1 5.0
  • Lgas/Ldigester/day such as higher than 7.0 Lgas/Ldigester/day.
  • the flow velocity of at least 0.0002 m/s may be vertical, i. e. the desired flow velocity refers to the velocity of the flow in the vertical direction. Limited or absence of cross sectional flow or horizontal flow is desirable.
  • the vertical flow is the flow along the longitudinal axes of the biofilm carrier, being the biofilm carrier located vertically along the longitudinal axis of the bioreactor.
  • the conducting digestion of the fluid occurs with a hydraulic retention time of 120 hours or less while maintaining a vertical flow velocity of at least 0.0002 m/s and a gas production rate of at least 5.0
  • Lgas/L digester/day (litersgas/liter digester volume/day) in such a manner as to maintain a substantial laminar vertical flow through the biofilm carriers.
  • S ubstantial laminar flow is defined as a flow that is mostly laminar, i.e. more than 80% such as more than 90% laminar.
  • the substantial laminar flow may be locally turbulent e.g. having . Reynold's number between 1 and 2500. Due to the microbial immobilisation, the system can be operated at HRT's lower than 1 20 hours when accepting loss in methane production efficiency. This can be the case, if treatment capacity is more important than methane yield or if an available carbon source is wanted in the effluent. However, the system can also be operated at a retention times higher than 120 hours.
  • the feedstock is digested under anaerobic conditions to produce biomethane with a hydraulic retention time of 120 hours, or less, such as less than 1 10 hours, such as less than 100 hours, less than 90 hours, less than 80 hours, less than 75 hours, less than 60 hours, less than 50 hours, or less than 40 hours or wherein the retention time is 20-120 hours, 30-120 hours, 40-120 hours, 50-120 hours, 75-120 hours, 100-120 hours, or such as 50-1 10 hours, 50-100 hours, 50-75 hours, while maintaining a flow velocity of at least 0.0002 m/s through the bioreactor and/or a gas production rate of at least 5.0 liters/liter digester volume/day in such a manner as to maintain a substantial laminar flow through said biofilm carriers.
  • a hydraulic retention time 120 hours, or less, such as less than 1 10 hours, such as less than 100 hours, less than 90 hours, less than 80 hours, less than 75 hours, less than 60 hours, less than 50 hours, or less than 40
  • the feedstock is digested under anaerobic conditions to produce biomethane with a hydraulic retention time of 120 hours, or less, while maintaining a flow velocity of at least 0.0002 m/s, such as a flow velocity between 0.0002 m/s to 0.08 m/s, such as between 0.0030 and 0.07, such as between 0.009 and 0.05, such as between 0.01 5 m/s to 0.045 m/s through the bioreactor and/or a gas production rate of at least 5.0 liters/liter digester volume/day in such a manner as to maintain a substantial laminar flow through said biofilm carriers.
  • a flow velocity of at least 0.0002 m/s, such as a flow velocity between 0.0002 m/s to 0.08 m/s, such as between 0.0030 and 0.07, such as between 0.009 and 0.05, such as between 0.01 5 m/s to 0.045 m/s through the bioreactor and/or a gas production rate of at least 5.0
  • the step of conducting digestion comprises forcing the fluid to flow between the at least two compartments downwardly towards the at least one underflow aperture or upwardly towards the at least overflow aperture.
  • the forcing the fluid to flow further comprises forcing the fluid to flow through a preferential flow path defined by the plurality of biofilm carriers.
  • the step of forcing the fluid to flow further comprises recirculating the fluid within each compartments.
  • the step of forcing the fluid to flow further comprises recirculating the fluid in between compartments. In some further embodiments, the step of forcing the fluid to flow further comprises recirculating the fluid within each sections.
  • the step of forcing the fluid to flow further comprises recirculating the fluid in between sections.
  • the method according to the fourth aspect further comprises:
  • the invention relates to a system for producing biogas, the system comprising:
  • At least one effluent tank for collecting effluents from the one or more
  • the system may further comprise a bioreactor comprising an insert according to the second aspect on the invention.
  • the invention in an eight aspect relates to a method of converting a C ontinuously Stirred tank Reactor (C ST R) having an internal surface into e.g. a fixed film, fixed orientation, fixed bedanaerobic digestion reactor, the method comprising installing an insert according to the second aspect of the invention within said C ST R .
  • the C ST R preferably occupying all or part of the C ST R digester volume.
  • the step of installing may comprise fastening the one or more baffles and/or one or more inserts to one of more locations of the internal surface of the C ST R .
  • Fastening may occur by means of bolt and nuts.
  • the fastening may also occur by welding.
  • the fastening may also occur by clamping, gluing or suspending against the C ST R wall
  • the step of installing may comprise, firstly inserting and fitting the insert in the C ST R and secondly installing, i.e. removably attaching, the plurality of biofilm carriers.
  • Insert and biofilm carriers may thus occur either in one step where an insert comprising biofilm carriers is installed or in two separate steps where following the insertion of the insert, biofilm carriers are installed.
  • Insert and biofilm carriers may be removably attached, meaning that may be attached in a way so that they can be later removed for inspections or maintenance.
  • the method further comprising growing a biofilm within the insert.
  • the invention relates to a method for performing maintenance of a C ST R modified according to the method of the eighth aspect of the invention, the method comprising: temporarily interrupting a normal operation of the modified C ST R; removing at least part of the insert; and re-installing the at least part of the insert.
  • At least part of the insert is removably attached so that it can be easily removed after installation.
  • the bioreactor on which maintenance according to the method according to the seventh aspect may comprises an insert according to the first aspect.
  • the invention relates to a method for performing maintenance of a bioreactor according to the second aspect of the invention.
  • At least part of the insert is at least one compartment of the insert.
  • the at least part of the insert may be at least one section of the insert.
  • the at least part of the insert may be one or more biofilm carriers within the compartments of the insert.
  • the invention relates to the use of a bioreactor according to the various aspects of the invention, for producing biogas, such as biomethane.
  • the invention relates to the use of a bioreactor according to the various aspects of the invention for rapid determination of a biomethane potential of a feedstock.
  • the invention relates to the use of a bioreactor according to the various aspects of the invention for producing a product produced by microbial organism supported on a biofilm.
  • the products may be chemical or biological products, such as organic acids, hydrogen gas, farmacological or fermentative products.
  • the bioreactor is suitable for being used in production of products that can benefit from the flow path defined by the insert and/or by the biofilm carriers.
  • the invention in a still further aspect relates to a method of aerobic or anaerobic digestion of a feedstock in the bioreactor according to the various aspects of the invention, the method comprising: feeding the feedstock into the compartments of the bioreactor;- digesting the feedstock by passing the feedstock through the compartments of the bioreactor with a retention time sufficient to digest the feedstock.
  • the compartments may contain biofilm carriers that have been pre-inoculated to obtain a biofilm with a suitable bacterial consortium.
  • the bacterial consortium may be a consortium of methane-producing
  • the methane producing microbes are of Archaea- type.
  • the feedstock may be mixed, or mixed at least in part between each
  • the feedstock may be feed simultaneously at several compartments across the bioreactor in order to form a feeding gradient preferably in order to form a feeding gradient in different parts of the bio digester.
  • the feedstock may be partly or completely recirculated through the bioreactor.
  • the feedstock may be partly recirculated between the compartments of the bioreactor.
  • the feedstock may be digested under anaerobic conditions to produce
  • biomethane with a hydraulic retention time of 120 hours or less while maintaining a flow velocity of at least 0.0002 m/s through the bioreactor and/or a gas production rate of at least 5.0 liters/liter digester volume/day in such a manner as to maintain a substantial laminar flow through the biofilm carriers.
  • the feedstock may have a chemical oxygen demand (C OD) of at Ieast 20.0 g/L, such as at least 30.0 g/L, at least 35 g/L, at least 40 g/L or at least 50 g/L or wherein the feedstock has a C OD of 20-300 g/L, 30- 300g/L, 40-300g/L, 50- 300g/L, 75-300 g/L, 100-300 g/L, such as 25-250 g/L, 30-200 g/L, 35-1 50 g/L, 40- 1 50 g/L, 50-150 g/L or such as 20-125 g/L, 30-1 OOg/L, 30-75 g/L, 30-50 g/L, 35-75 g/L, 40-100 g/L, 50-175 g/L, 50-200 g/L
  • C OD chemical oxygen demand
  • the feedstock may be digested at a temperature between 30 and 55eC, 37 and 53eC, such as between 37 and 48eC, such as between 37 and 40eC, such as between 40 and 44eC, such as between 44 and 48eC, such as between 48 and 53eC .
  • the feedstock may be digested at a pH between 6.6 and 8.5, such as between 6.8 and 7.4, such as between 7.0 and 7.4, such as between 7.0 and 7.2.
  • the pH is adjusted by recirculation and/or by addition of pH adjusting agents, such as ammonia.
  • P H may be adjusted also by other alkaline or acidic adjusting agents and/or through the use of buffer solutions.
  • the retention time is less than 1 10 hours, such as less than 100 hours, less than 90 hours, less than 80 hours, less than 75 hours, less than 60 hours, less than 50 hours, or less than 40 hours or wherein the retention time is 20-120 hours, 30-120 hours, 40-120 hours, 50-120 hours, 75-120 hours, 100-120 hours, or such as 50- 1 10 hours, 50-100 hours, 50-75 hours.
  • the flow velocity is at least 0.00025 m/s, such as at least 0.0005 m/s, at least 0.00075 m/s, at least 0.001 m/s, at least 0.0025 m/s, at least 0.005 m/s, or at least 0.0075 m/s or wherein the flow velocity is 0.0002-0.01 5 m/s, such as 0.0002-0.0125 m/s, 0.0002-0.01 m/s, 0.0002-0.0075 m/s, 0.0002- 0.005 m/s, or such as 0.00025-0.01 m/s, 0.0005-0.01 m/s, 0.00075-0.01 m/s, 0.001 -0.01 m/s, 0.0025-0.01 m/s, 0.005-0.01 m/s, or 0.0075-0.01 m/s.
  • the gas production rate is at least 6.0 liters/liter digester volume/day, such as 7.0 liters/liter digester volume/day, at least 8.0 liters/liter digester volume/day, 9.0 liters/liter digester volume/day, at least 10.0 liters/liter digester volume/day, such as at least 12.5 liters/liter digester volume/day, at least 15 liters/liter digester volume/day or at least 20 liters/liter digester volume/day, and/or wherein the gas production rate is 5.0-20 liters/liter digester volume/day, such as 6.0- 20 liters/liter digester volume/day, 7.0-20 liters/liter digester volume/day 8.0-20 liters/liter digester volume/day, 9.0 liters/liter digester volume/day, or 10-20 liters/liter digester volume/day.
  • the feedstock may be a biomass.
  • the biomass is selected from the group consisting of waste, sewage, manure, and/or a cellulosic, hemicellulosic, lignocellulosic or starch containing biomass selected from wheat straw, corn stover, sugar cane bagasse, sweet sorghum bagasse, or empty fruit bunches.
  • the waste is selected from the group consisting of municipal solid waste (MSW), industrial waste, animal waste or plant waste.
  • the waste contains a level of total solids greated than 7% (w/w), such as greater than 8% (w/w), greater than 9% (w/w), greater than 1 0% (w/w), such as 7-20% (w/w), 8-20% (w/w), 9-20% (w/w),10-20% (w/w), or 1 5-20% (w/w).
  • the biomass have been pre-treated by hydrothermal pre-treatment, enzymatic hydrolysis and/or aerobic digestion.
  • the invention relates to an insert, said insert preferably comprises
  • the cross section of the outer tubular structure (A1 ) is polygonal, circular, elliptical shaped.
  • the longitudinal extension of the tubular structure is in preferred embodiments straight or has one or more straight sections or is curved, such as comprising one or more curved sections.
  • An insert according to preferred embodiments of the invention may preferably, comprise means for supporting said biofilm carrier(s) located inside said tubular structure.
  • said biofilm carrier(s) is(are) suitable for biofilm growth upon exposure to a flow of fluid containing biofilm precursors, said biofilm carrier(s) comprising a three dimensional structure having at least one surface comprising cavities and protrusions thereby providing a rough surface.
  • said rough surface has a rough surface area Ra between 3 and 6 mm.
  • said rough surface has preferably a minimum valley Rv of 1 mm.
  • said rough surface has preferably a peak depth R p of 2 mm.
  • said three dimensional structure comprises openings, such as holes throughout said at least one surface.
  • said three dimensional structure is a tubular porous three dimensional structure.
  • said porous are open porous.
  • said three dimensional structure is or comprises a threaded structure.
  • P referred embodiments of an insert may preferably comprise a biofilm, preferably on the biofilm carrier(s), such as a biofilm comprising one or more different microorganisms adapted to aerobic or anaerobic digestion/fermentation.
  • an insert may define a preferential vertical path along and inside said biofilm carriers.
  • An insert according to preferred embodiments of the invention may be configured for, when inserted into a tank reactor and when said tank reactor is in operation, providing a fluid flow substantially parallel to the biofilm formation is produced.
  • the invention relates to a bioreactor system preferably comprising one or more FADs and one or more C ST Rs, the C ST Rs each preferably comprising:
  • a tank reactor having one or more side walls and a bottom wall having an internal surface thereby defining a reactor volume and the tank reactor further comprising an inlet into and an outlet out from the reactor volume;
  • the FADs each preferably comprising:
  • one of the openings of a FAD is in fluid communication with the reactor volume of a C ST R .
  • P referably the one or more, such as all of the FADs is/are/comprise(s) said insert according to the certain second aspect of the invention.
  • said one or more side walls of said tank reactor are said continuous closed side wall of an insert according to the certain second aspect of the invention.
  • P referred embodiments of a bioreactor according to the certain third aspect of the invention may further comprise means for forcing, when in operation and the longitudinal extension of the tubular structure is vertical or substantial vertically orientated, a fluid to flow downwardly or upwardly through said FAD(s) .
  • said means for forcing a fluid to flow are said biofilm carrier(s).
  • a bioreactor according to the certain third aspect may further comprising means for promoting removal of precipitate deposited or located on the internal surface of said bottom wall of said tank reactor.
  • said means for promoting removal of precipitate may be one or more rotating means, such as one or more rotating scrapers.
  • each of said one or more rotating scrapers may have a scraping edge and a top edge opposite to said scraping edge.
  • the tank reactor may in preferred embodiments comprise a bottom chamber defined/located between the internal surface of said bottom wall and a lowest level/part of said FAD(s).
  • the bottom chamber may preferably comprise said means for promoting removal of precipitate.
  • the means for promoting removal of precipitate may preferably be adapted to define, when not in operation, static zones within said bottom chamber wherein flow between FADs and said static zones is lower than a desired value, while when in operation, said static zones becomes mixing zones wherein flow between FADs and said static zones is higher than said desired value.
  • a bioreactor according to the invention may further comprising means for keeping FAD(s) at said desired distance from said internal surface of said bottom wall.
  • the means for keeping said FAD(s) at said desired distance may preferably be a plurality of protrusions located on said one or more side walls of said tank reactot.and/or may be a curvature of said bottom wall, said curvature gradually reducing said width/size/diameter of said tank reactor, said width/size/diameter defined by said one or more side walls of said tank reactor.
  • a cross-flow in between not subsequent FADs may be lower than a desired value.
  • the total volume of the FAD(s) may be at least 10%, such as at least 20 %, preferably at least 30%, such as at least 40%, preferably at least 50%, such as at least 60% of the total volume of the biological treatment device.
  • the ratio of volume FAD(s) to C ST R(s) may in the range of 0.01 to 0.05, such as in the range of 0.05-0.1 , preferably in the range of 0.1 -0.25, such as in the range of 0.25-0.5, preferably in the range of 0.5-0.75, such as in the range of 0.75-1 , preferably in the range of 1 -3, 2-5, or even in the range of 5-10.
  • the ratio of volume FAD(s) to C ST R(s) may less than 0.01 , such as less than or -0.025, preferably less than or - 0.05, such as less or - 0.1 , preferably less than or -0.2, such as less than or -0.3, preferably less than or -0.4, such as less than or -0.5, preferably less than or 0.6, such as less than or - 0.7, preferably less than or -0.8, such as less than or -0.9, preferably less than or -1 .0, such as less than or -1 .2, such as less than or -1 .4, preferably less than or -1 .6, such as less than or -1 .8, preferably less than or -2.0, such as less than or -2.5, preferably less than or -3.0, such as less than or -3.5, preferably less than or -4.0, such as less than or -5.0, preferably less than or -7.5, such as less than or -10, or even more
  • the ratio between the circumference a cross section of the tubular structure (A1 ) and/or of the FAD(s) and the circumference of a cross section one or more fluid penetrable biofim carriers (A4) may be s maller than 0.9, such as smaller than 0.8, preferably smaller than 0.7, such as smaller than 0.6, preferably smaller than 0.5, such as smaller than 0.4, preferably smaller than 0.3, such as smaller than 0.2, preferably smaller than 0.1 . (S ee also e.g. fig. 31 )
  • circumference of a cross section is preferably meant that the circumferences are evaluated at the same horizontal level measured from a lower position of the element in question; and preferably "horizontal" may be perpendicular to the direction of gravity.
  • a bioreactor system may comprise at least two FADs and an C ST R and comprising flow regulating means, such as valve, fluid guides and pumps, for regulating flow of fluid through each of the FADs independently of independently of each other, so as to provide e.g. a smoothing in one of the FADs and a polishing in another FAD.
  • flow regulating means such as valve, fluid guides and pumps, for regulating flow of fluid through each of the FADs independently of independently of each other, so as to provide e.g. a smoothing in one of the FADs and a polishing in another FAD.
  • a bioreactor system may comprise one FAD and/or a C ST R with a FAD and one or more C ST Rs being in fluid communication so as to exchange fluid.
  • the invention relates to a bioreactor system for Biphase Fast Anearobic Digestion, the system preferably comprising
  • tank reactor having one or more side walls and a bottom wall having an internal surface thereby defining a reactor volume the tank reactor further comprising an inlet into and an outlet out from the reactor volume
  • a break-up device such as a down sizing device, being in fluid
  • the bioreactor system further comprising one or more FADs comprising
  • an outer tubular structure (A1 ) having a longitudinal extens ion (L), being made from a fluidic non-penetrable material and having an opening (A2, A3) at each end of the outer tubular structure so as define a flow passage inside the outer tubular structure extending between said openings, and - one or more fluid penetrable biofilm carriers (A4) arranged inside said outer tubular structure (A1 );
  • one of the openings of a FAD is in fluid communication with the reactor volume.
  • the break-up device such as a down-sizing device may comprise or further comprise a cutting/shredding element for break-up solid material by a cutting/shredding action.
  • the break-up device may comprise or further comprise a heating element for heating an interior volume the break-up device, preferably the heating element is adapted to an aqueous fluid present in the interior volume to a temperature of at least 100°C , such as at least 120°C, preferably at least 140°C, such as at least 1 60°C .
  • the break-up device may comprise or further comprise a pressurization element for pressurizing an interior volume of the break-up device, preferably the pressurization element is adapted to pressurize an aqueous fluid to a pressure of least 1 .1 bar, such as at least 1 .2 bar, preferably at least 1 .4 bar, such as at least 1 .8 bar.
  • the break-up device may comprising or further comprise means for providing enzymatic reactions.
  • the break-up device may comprise or further comprise a feeding element for feeding enzymes into an interior volume of the break-up device.
  • the break-up device may comprise or further comprise a catalytic element for catalytic reduction of biological material.
  • the total volume of the FAD(s) may be at least 10%, such as at least 20 %, preferably at least 30%, such as at least 40%, preferably at least 50%, such as at least 60% of the total volume of the tank reactor.
  • the invention relates to a system for processing sludge, such as digestate, the system preferably comprises:
  • a biological treatment device in which the sludge is at least partly produced during a biological treatment of organic material contained in water, - an extraction device for extracting sludge from said biological treatment device;
  • a processing device configured for receiving the extracted sludge
  • a feeding device for feeding at least a fraction of the processed sludge into said biological treatment device and/or another biological treatment device.
  • the biological treatment device may be a bioreactor system according to the certain third aspect of the invention.
  • the processing device may be a break-up device as disclose in connection with the certain fourth aspect of the invention.
  • the processing device may preferably be internally arranged in the reactor.
  • the processing device may be arranged outside the reactor and in fluid communication with the reactor by lines.
  • the processing device may comprises or further comprise a
  • the processing device may comprise or further comprise a heating element for heating an interior volume the break-up device, preferably the heating element is adapted to an aqueous fluid present in the interior volume to a temperature of at least 100°C , such as at least 120°C, preferably at least 140°C, such as at least 1 60°C .
  • the processing device may comprise or further comprise a
  • pressurization element for pressurizing an interior volume of the break-up device, preferably the pressurization element is adapted to pressurize an aqueous fluid to a pressure of least 1 .1 bar, such as at least 1 .2 bar, preferably at least 1 .4 bar, such as at least 1 .8 bar.
  • the processing device may comprise or further comprise means for providing enzymatic reactions.
  • the processing device may comprise or further comprise a feeding element for feeding enzymes into an interior volume of the processing device.
  • the processing device may comprise or further comprise a catalytic element for catalytic reduction of biological material.
  • a system according to the certain fifth aspect may preferably further comprise one or more FADs preferably comprising
  • one of the openings of a FAD is in fluid communication with the biological treatment device.
  • one or more of the FADs may be an insert according to the certain second aspect of the invention.
  • the biological treatment device may be a combination of a one or more C ST Rs and one or more FADs.
  • a system according to the certain fifth aspect may further comprise a combination of one or more C ST Rs and one or more FADs.
  • the total volume of the FAD(s) may be at least 10%, such as at least 20 %, preferably at least 30%, such as at least 40%, preferably at least 50%, such as at least 60% of the total volume of the biological treatment device.
  • the "another biological treatment device” may preferable be configured to
  • the invention relates to a method of operating a bioreactor system, said bioreactor preferably being a bioreactor according to the certain third aspect of the invention and/or a system according to certain fourth aspect said method preferably comprises:
  • said fluid containing biofilm precursors may be a feedstock having a C OD at least 30.0 gr/L
  • the conducting digestion of said fluid may occur with a hydraulic retention time of 120 hours or less while maintaining a flow velocity of at least 0.0002 m/s and a gas production rate of at least 5.0 Lgas/Ldigester/day in such a manner as to maintain a substantial laminar flow through said biofilm carriers.
  • the conducting digestion may comprise forcing said fluid to flow downwardly or upwardly through the tubular structure.
  • the forcing said fluid to flow may comprise or may further comprise forcing said fluid to flow through a preferential flow path defined by said plurality of biofilm carriers.
  • the forcing said fluid to flow may comprise or may further comprise recirculating said fluid within each compartments.
  • the forcing said fluid to flow may comprise or may further comprise recirculating said fluid in between compartments.
  • the forcing said fluid to flow may comprise or may further comprise recirculating said fluid within each sections.
  • the forcing said fluid to flow may comprise or may further comprise recirculating said fluid in between sections.
  • a method according to the certain sixth aspect may comprise or further comprise:
  • the invention relates to a method of operating a an insert, a bioreactor, said bioreactor being preferably a bioreactor system according to third aspect or a system according to fourth aspect of the invention or system or reactors as disclosed herein, said method preferably includes one or more of the features of the sixth aspect of the invention, the method may preferably comprise
  • the amount preferably measured in kg/sec of substrate fed into the C ST R or reactor volume may be higher than the amount measured in kg/sec of digestate fed into the C ST R or reactor volume.
  • the combination of a FAD feeding digestate into a C ST R or tank reactor may be considered to be an FAD-assisted C ST R as disclosed herein, and the FAD produces digestate from a substrate and at least a fraction of this digestate is introduced into the C STR which receives substrate.
  • the ratio between substrate and digestate may be larger than 1 .0, such as larger than 1 .5, preferably larger than 2, such as larger than 2.5, preferably larger than 3.0, and preferably smaller than 5.0. Accordingly, the amount of digestate fed into the C ST R or tank reactor may be smaller than the amount of substrate fed into the C STR or tank reactor.
  • the invention relates to a a system for producing biogas, said system preferably comprises:
  • the invention relates to a method of converting a
  • C ST R C ontinuously Stirred tank Reactor having an internal surface at least in part into a fixed film, fixed orientation, fixed bed anaerobic digestion reactor
  • said method preferably comprises installing one or more inserts according to the certain second aspect of the invention within said C ST R, so as to preferable define a C ST R/FAD hybrid.
  • said installing may comprise or further comprise, firstly inserting and fitting said insert in said C ST R and secondly installing said plurality of biofilm carriers.
  • a method according the certain eighth aspect may further comprise growing a biofilm within said insert.
  • At least two insert may be installed together with flow regulating means, such as valve, fluid guides and pumps, for regulating flow of fluid through each of the FADs independently of independently of each other, so as to provide e.g. a smoothing in one of the FADs and a polishing in another FAD.
  • flow regulating means such as valve, fluid guides and pumps
  • the invention relates to a method for performing maintenance of a C ST R modified according to the method according the certain eighth aspect, or a bioreactor according to the certain third aspect and/or a system according to the certain fourth aspect employing an insert according to the certain second aspect, said method preferably comprises:
  • the invention relates to the use of a bioreactor according to the certain third aspect and/or a system according to the certain fourth aspect of the invention for producing biogas.
  • the invention relates to the use of a bioreactor according to the certain third aspect and/or a system according to the certain fourth aspect of the invention, for, preferably rapid, determination of a biomethane potential of a feedstock.
  • the invention relates to the use of a bioreactor according to any of the certain third aspect and/or or a system according to the certain fourth aspect of the invention, to produce a product produced by microbial organisms supported on a biofilm.
  • the invention relates to a method of aerobic or anaerobic digestion of a feedstock in a bioreactor according to the certain thirds aspect and/or a system according to the certain fourth aspect, the method preferably comprises the steps of:
  • the compartments may contain biofilm carriers, which have been pre- inoculated to obtain a biofilm with a suitable bacterial consortium.
  • the bacterial consortium may be a consortium of methane producing bacteria, such as Archaea bacteria.
  • the feedstock may be mixed between each compartment.
  • feedstock may be feed simultaneously at several compartments across the bioreactor in order to form a feeding gradient preferably in different parts of the bio digester.
  • the feedstock may be partly or completely recirculated through the bioreactor.
  • the feedstock may be partly recirculated between the compartments of the bioreactor.
  • the feedstock may be digested under anaerobic conditions to produce biomethane with a hydraulic retention time of 120 hours or less while maintaining a flow velocity of at least 0.0002 m/s through the bioreactor and/or a gas production rate of at least 5.0 liters/liter digester volume/day in such a manner as to maintain a substantial laminar flow through said biofilm carriers.
  • the feedstock may have a chemical oxygen demand (C OD) of at least 20.0 g/L, such as at least 30.0 g/L, at least 35 g/L, at least 40 g/L or at least 50 g/L or wherein the feedstock has a C OD of 20-300 g/L, 30- 300g/L, 40-300g/L, 50- 300g/L, 75-300 g/L, 100-300 g/L, such as 25-250 g/L, 30-200 g/L, 35-1 50 g/L, 40- 1 50 g/L, 50-150 g/L or such as 20-125 g/L, 30-100g/L, 30-75 g/L, 30-50 g/L, 35-75 g/L, 40-100 g/L, 50-175 g/L, 50-200 g/L.
  • C OD chemical oxygen demand
  • the feedstock may be digested at a temperature between 30 and 55eC .
  • the feedstock may be digested at a temperature between 37 and 48eC .
  • the feedstock may be digested at a pH between 6.6 and 8.5.
  • the feedstock may be digested at a pH between 6.8 and 7.4.
  • the pH may be adjusted by recirculation and/or addition of pH adjusting agents.
  • the retention time may be less than 1 1 0 hours, such as less than 100 hours, less than 90 hours, less than 80 hours, less than 75 hours, less than 60 hours, less than 50 hours, or less than 40 hours or wherein the retention time is 20-120 hours, 30-120 hours, 40-120 hours, 50-120 hours, 75-120 hours, 100-120 hours, or such as 50-1 10 hours, 50-100 hours, or 50-75 hours.
  • the flow velocity may be at least 0.00025 m/s, such as at least 0.0005 m/s, at least 0.00075 m/s, at least 0.001 m/s, at least 0.0025 m/s, at least 0.005 m/s, or at least 0.0075 m/s or wherein the flow velocity is 0.0002-0.015 m/s, such as 0.0002-0.0125 m/s, 0.0002-0.01 m/s, 0.0002-0.0075 m/s, 0.0002- 0.005 m/s, or such as 0.00025-0.01 m/s, 0.0005-0.01 m/s, 0.00075-0.01 m/s, 0.001 -0.01 m/s, 0.0025-0.01 m/s, 0.005-0.01 m/s, or 0.0075-0.01 m/s.
  • the gas production rate may be at least 6.0 liters/liter digester volume/day, such as 7.0 liters/liter digester volume/day, at least 8.0 liters/liter digester volume/day, 9.0 liters/liter digester volume/day, at least 10.0 liters/liter digester volume/day, such as at least 12.5 liters/liter digester volume/day, at least 1 5 liters/liter digester volume/day or at least 20 liters/liter digester volume/day wherein the gas production rate is 5.0-20 liters/liter digester volume/day, such as 6.0- 20 liters/liter digester volume/day, 7.0-20 liters/liter digester volume/day 8.0- 20 liters/liter digester volume/day, 9.0 liters/liter digester volume/day, or 10-20 liters/liter digester volume/day.
  • the gas production rate is 5.0-20 liters/liter digester volume/day, such as 6.0- 20 liters/liter digester volume/day
  • the feedstock may be a biomass.
  • the biomass may be selected from the group consisting of but not limited to waste, sewage, manure, or a cellulosic, hemicellulosic, lignocellulosic or starch containing biomass selected from wheat straw, corn stover, sugar cane bagasse, sweet sorghum bagasse, distillery vinasse, empty fruit bunches, abattoir waste, animal food, dairy products or organic industry residual products.
  • the waste may be selected from the group consisting of municipal solid waste (MSW), liquefied organic components of MSW, industrial waste, animal waste, plant waste or wastes from abattoirs, restaurants, dairy processing, and tanneries.
  • the waste may contain a level of total solids greater than 7% (wA/v), such as greater than 8% (w/w), greater than 9% (w/w), greater than 1 0% (w/w), such as 7-20% (w/w), 8-20% (w/w), 9-20% (w/w),10-20% (w/w), or 1 5-20% (w/w).
  • the biomass may have been subjected at least in part to one or more of hydrothermal pre-treatment, enzymatic hydrolysis and/or aerobic digestion.
  • the feedstock may be digested under anaerobic conditions to produce biomethane with a hydraulic retention time of 120 hours, or less, such as less than
  • 1 0 1 10 hours such as less than 100 hours, less than 90 hours, less than 80 hours, less than 75 hours, less than 60 hours, less than 50 hours, or less than 40 hours or wherein the retention time is 20-120 hours, 30-120 hours, 40-120 hours, 50-120 hours, 75-120 hours, 100-120 hours, or such as 50-1 10 hours, 50-100 hours, 50- 75 hours, while maintaining a flow velocity of at least 0.0002 m/s through the
  • the feedstock may be digested under anaerobic conditions to produce 20 biomethane with a hydraulic retention time of 120 hours, or less, while maintaining a flow velocity of at least 0.0002 m/s, such as a flow velocity between 0.0002 m/s to 0.08 m/s, such as between 0.0030 and 0.07, such as between 0.009 and 0.05, such as between 0.01 5 m/s to 0.045 m/s through the bioreactor and/or a gas production rate of at least 5.0 liters/liter digester volume/day in such a manner as 25 to maintain a substantial laminar flow through said biofilm carriers.
  • a flow velocity of at least 0.0002 m/s such as a flow velocity between 0.0002 m/s to 0.08 m/s, such as between 0.0030 and 0.07, such as between 0.009 and 0.05, such as between 0.01 5 m/s to 0.045 m/s through the bioreactor and/or a gas production rate of at least
  • the feedstock may be digested under anaerobic conditions to produce biomethane with a hydraulic retention time of 120 hours, or less, while maintaining a flow velocity of at least 0.0002 m/s through the bioreactor and/or a gas
  • L/L/D 5.0 liters/liter digester volume/day
  • L/L/D 5.0 liters/liter digester volume/day
  • the invention relates to a FAD-assisted CSTR system
  • the feeding is provided by fluid connections, such as tubes.
  • a in FAD-assited CSTR system the FAD may be as disclosed herein (including embodiments where the FAD is comprised by an insert as disclosed herein)
  • the substrates fed into said FAD and CSTR may be essentially identical, such as identical, e.g. from same substrate tank.
  • 0.1-99.9 % of the FAD digestate may be fed into said CSTR.
  • at least 0.1, 1.0, 10, 20, 40, 60, 80, 90, 95, or 99% of the FAD digestate may be fed into said CSTR.
  • at least 0.1-1,1-10, 10-20, 20-40, 40-60, 60-80, 80-95, 95-99.9% of the FAD digestate may be fed into said CSTR.
  • such a FAD-assisted CSTR system may be suitable for continuous operation, such as production of biogas.
  • the invention relates to a method of producing biogas comprising the use of a system as disclosed herein, and/or a FAD is disclosed herein (including embodiments where the FAD is comprised by an insert as disclosed herein).
  • Figure 1A shows the example of a bioreactor suitable for practicing methods of the invention.
  • Figure 1 B shows schematically one embodiment of an insert according to one aspect of the invention.
  • Figure 1C shows one embodiment of the insert according to one aspect of the invention.
  • Figure 1D shows another embodiment of the insert according to one aspect of the invention.
  • Figure 1E shows a further embodiment of the insert according to one aspect of the invention.
  • FIG. 1F-1K shows further embodiments in cross sectional views of inserts according to the invention.
  • the biofilm carriers are illustrated as cross hatched elements in the figures, and flow directions internally are illustrated by arrows. Fluid may enter into the inserts as illustrated in e.g. fig.1 A or 1 B in which cases the wall of the.
  • FIG 2A shows a bioreactor similar to that shown in Figure 1 A, but with more detailed features, thus showing a schematics of the CSTR tank fitted with the FAD insert.
  • Figure 2B shows the example of a bioreactor of figure 2 with reference signs.
  • FIG 2C shows section of an insert according to some embodiments of the invention.
  • F igure 3A shows the basic fluid flow patterns achieved in one quarter section of the bioreactor when in operation thus showing flow through a quarter section of the bioreactor shown in figure 2A and 2B.
  • F igure 3B shows the basic fluid flow patterns achieved in one quarter section of the bioreactor when in operation where the porous tubular biofilm carrier are shown correctly, being figure 3A and figure 3B a cross section.
  • F igure 3C shows schematically a bioreactor with a co-centrically arranged tubular element.
  • the fluid motion is shown as upward inside the co-centrically arranged tubular element and is shown as downward outside the co-centrically arranged tubular element. The direction may be reversed.
  • F igure 3D and 3E illustrates in cross sectional views different configuration of biofilm carriers (cross hatched elements) inside the bioreactor of fig. 3C .
  • F igure 4 shows a schematic illustration of fluid flow patterns or paths, i.e. a schematic top view of two FAD digester sizes showing different chamber distributions, flow patterns and circulation flow directions and placements.
  • F igure 5A and 5B shows a porous matrix providing multiple "directions" for biomass accumulation in the biofilm.
  • F igure 6 and F igure 7 show schematic illustrations of two embodiments of a laboratory scale test device.
  • F igure 7A shows schematically a process according to the invention, in which fluid is treated initially in an upstream bioreactor (BR) and subsequently streams into a downstream FAD.
  • BR upstream bioreactor
  • F igure 7B shows schematically the process of figure 7A in which the bioreactor I is illustrated as reactor with a stirrer and/or break-up device at the bottom of the reactor.
  • the bioreactor l is in fluid communication through a line (shown with an optional shut- off valve) to a downstream FAD II.
  • a number of lines are provided to distribute fluid between the reactor I and the FAD II.
  • Fucid to be treated is fed into the system illustrated from one or more of the two lines shown to the left in figure 7B.
  • F igure 7B illustrates in particular a layout for an extended FAD, designed to process mono or bi-phasic substrates (liquid and solid), called BiFAD for bi-phasic FAD.
  • the system comprising a pulper (break-up device), working in a fed-batch mode (system I in fig. 7B) and a FAD (system II in fig. 7B). Liquid feed is supplied to the FAD through the liquid input.
  • F ibrous feed (which require extended hydrolysis) is supplied to the system I, through the solid input.
  • the solids will be pulped with fresh feedstock or/and effluent from the FAD.
  • the sludge from the FAD can either be pumped out of the system from system II or reinjected to System I. Re-injecting the sludge has:
  • the sediment/precipitate will accumulate in system I and II; in system I, the pulping screw will also act as a scrapper and push the s ludge toward the sludge collection of system I. In system II, the FAD scrapper will push the sludge toward the sludge collection. Depending on the properties of the sludge (organic or mineral), it will can decided to recirculate the sludge or to collect it.
  • the pulping is a bio-pulping, as it combines mechanical and biological activity. As permanent inocuation fron the FAD is applied, it will produce gas. Hydrolytic reactors have sometimes a production of H2. The gas may be used to improve the recirculation in the FAD by creating an air lift in the ascending tubes. This should decrease the workload of the recirculation pumps. If the system is used with only liquid feed, the first system can be used to increase your treatment on the sludge. If the system is used with solid liquid only, then the system is only
  • two bio-pulpers can be used in parallel (operated in fed-batch) connected to one system II.
  • F igure 7C 1 shows schematically a process according to the invention, in which fluid is treated initially in an upstream FAD and subsequently streams into a downstream C ST R .
  • F igure 7C 2 shows schematically the process of figure 7C 1 in which recirculation is implemented for the FAD, the C ST R and between the FAD and C ST R . It is noted that one or more of the recirculations may be omitted. F urther, outputs are shown at the bottom of the FAD and the C ST R and that the outputs are connected through a common line which may be connected to other FADs and/or C ST R to collect the output from such devices.
  • F igures 7D-7F shows schematically various combinations of C ST Rs and FADs being considered within the scope of the present invention.
  • the figures shows the combinations with the same nomenclature as used in figure 7C 1 and may be embodied as illustrated in fig. 7C2, that is typically that the FADs and the C ST Rs are separate units being in fluid communication through lines.
  • F igure 7G -7J shows schematically various combinations of C ST Rs and FAD in which the C ST Rs and FAD are integrated into a single unit and the boxes in the figures illustrates from left to right the fluid motion; that is for instance with respect to fig. 7G that the FAD is an upstream process/device and the C ST R is a downstream process.
  • fig. 7D may illustrate a first mode of operation in which fluid is treated in a upstream C ST R and flows into a
  • F igure 7E may illustrate a further mode of operation in which the fluid flows from a FAD to an downstream C ST R .
  • F igure 7K in combination with either figure 7L and 7M shows schematically a manner of integrating a C ST R and a FAD into a single unit -
  • F igure 7k illustrates the single unit in a 3-dimensional view with an indication of a preferred flow path.
  • F igure 7L illustrates as seen from above, the example with the FAD are arranged in the centre of the reactor (the biofilm carriers are left out) .
  • F igure 7M illustrates as seen from above, the example with the FAD arranged outside the C ST R which is arranged in the centre of the reactor.
  • F igures 7N-7V shows further combinations of C ST Rs and FADs being considered within the scope of the present invention.
  • the figures shows the combinations with the same nomenclature as used in previously and may be embodied as illustrated in fig. 7C 2 or 7K.
  • F igure 8 shows Ideal Retention Time Distribution (RTD) results of "well mixed" cascading C ST R's.
  • N order of reactors of the species.
  • F igure 9. shows experimental results of Retention Time Distribution analysis RT D graph from methylene blue passing through the three consecutive FAD digesters.
  • F igure 10 shows gas production (diamonds) and feed rate (circles) in liters per day over the course of 95 days biofilm build-up of the FAD system described in example 1 using the LOF feed described in Table 2.
  • F igure 1 1 shows C OD removal and H RT vs. time during FAD load-up with liquefied organic fraction of MSW.
  • F igure 12 shows a P hoto of biofilm carrier with biofilm attached.
  • F igure 13 shows continuous operation during rapid and profound temperature regime changes, i. e. the gas produced per litre of 53 gC OD/L feed vs time during transition between thermophilic and mesophilic temperature range.
  • F igure 14 shows the Lengthy stable FAD operation at 91 hours H RT - 2 L feed/day into 7,5 L digester, showing the gas produced (201 ) and the feed in (202).
  • F igure 1 5 shows the stable C OD conversion efficiency during lengthy operation at 91 hours H RT.
  • F igure 16 shows VF A and C OD content of effluent vs time (days).
  • F igure 17 shows a digester VFA concentration vs. C OD conversion efficiency in the same digester.
  • F igure 18 shows Biogas production before and after lengthy biofilm exposure to atmospheric oxygen.
  • F igure 19 shows Gas production from lignocellulosic Thin stillage fed to the FAD digester, i. e. gas production from thin stillage from 2 nd generation bioethanol production fed to the FAD digester.
  • F igure 20 shows gas production from pig manure fed to the FAD digester.
  • F igure 21 shows gas production through a shock test.
  • F igure 22 compares gas production for a single feed point and for a multi feed point for gas production (serie 1 ) and for the substrate.
  • F igure 23A illustrates schematically an embodiment of a system according to invention.
  • the system comprising a reactor tank with a stirrer inside. S ubstances are taken out at the bottom of the reactor tank and processed in a processing device and re-introduced into the reactor tank after processing.
  • F igures 23B-E illustrates schematically different configurations and process for post treatment of digestate according to preferred embodiments of the invention.
  • the embodiments of figures 23B-E may advantageously be used in combination with the system of figure 23A as disclosed in further details below.
  • F igure 24A-C illustrates schematically a test configuration comprising an FAD and C ST R, wherein the C ST R is arranged upstream of a C ST R (also termed an FAD- assisted C STR or FAD/C ST R combi herein); the figure also indicates an example of the feed rates to the FAD and C ST R .
  • F igure 25 is a graph illustrating FAD digestate and substrate contribution to the total volumetric input to the C ST R at different hydraulic retention times (H RT).
  • F igure 26 is a graph illustrating gas flow rate from the FAD-assisted C ST R as a function of hydraulic retention time (H RT).
  • F igure 27 is a graph illustrating pH in the FAD-assisted C ST R as function of hydraulic retention time (H RT).
  • F igure 28 is a graph illustrating volatile fatty acid intermediates in the FAD- assisted C STR .
  • F igure 29 is a graph illustrating performance of FAD-assisted C ST as a function of hydraulic retention time (H RT).
  • F igure 30 is a graph illustrating performance of various biogas systems as a function of hydraulic retention time (H RT); Adapted from figure 2 of H. Hartmann and B. K. Ahring (2006);
  • F igure 31 schematically illustrates three cross sectional view of preferred embodiments of an FAD according to the present invention
  • the invention provides a method of anaerobic digestion to biomethane comprising the steps of
  • a substrate feedstock having C OD content at least 30.0 g/L into a fixed film, fixed orientation, fixed bed bioreactor system in which the immobilization matrix is characterized in comprising a plurality of vertically oriented, porous tubular carriers supporting biofilm, and in which mixing zones are provided both above the upper openings and below the lower openings of the tubular carriers, and conducting anaerobic digestion of the feedstock with a hydraulic retention time of 120 hours or less while maintaining a flow velocity of at least 0.0002 m/s and a gas production rate of at least 5.0 litres gas/litre digester volume/day in such manner as to maintain a substantially laminar flow through the tubular carriers as well as mixing within each of the mixing zones.
  • the invention provides an anaerobic digestion bioreactor comprising a cylindrical tank having a plurality of internal, vertical biofilm carrier compartments defined by baffles or walls made from corrosion resistant and liquid impermeable material that are open at the top, where in each carrier compartment comprises a shortened wall or underflow aperture on one side at the bottom which serves as an opening into another carrier compartment whereby fluid flows can be directed through succeeding compartments, and wherein a plurality of the carrier compartments further comprise a shortened wall or overflow aperture at the top on a side other than that side which contains a shortened wall or underflow aperture at the bottom which serves as an opening into another carrier compartment whereby fluid flows can be directed through succeeding compartments, optionally further comprising a rotable scraper that is adapted to define sealed sections in a sedimentation zone situated beneath the lowest edge of the carrier compartments when in a closed position or to permit removal of sedimented solids when in an open position.
  • the invention provides an insert for converting a
  • C ST R continuously stirred tank reactor
  • baffles made from corrosion resistant and liquid impermeable material that define a plurality of vertical biofilm carrier compartments that are open at the top, each of which has a shortened wall or underflow aperture on one side at the bottom which serves as an opening into another carrier compartment whereby fluid flows can be directed through succeeding compartments, and most of which have a shortened wall or overflow aperture at the top on a side other than that which contains a shortened wall or underflow aperture at the bottom which serves as an opening into another carrier compartment whereby fluid flows can be directed through succeeding compartments.
  • the invention provides a method of converting a C ST R tank into a fixed film, fixed orientation, fixed bed anaerobic digestion reactor comprising the steps of-
  • the invention provides methods and laboratory scale devices for rapid determination of biomethane potential of tested substrates.
  • biofilms By maintaining very high biogas production rates in fixed film, fixed orientation, 1 5 fixed bed anaerobic digestion systems, biofilms can be maintained in excellent productive condition without excess accumulation of biomass and associated clogging problems.
  • biogas flows should be maintained at least at 5.0 liters total gas/liter digester volume/day (L/L/D), or at least 6.0 L/L digester volume/day, or at least 7.0, or at least 8.0, or at least 9.0.
  • a processed waste stream typically has high C OD content at Ieast 30.0 g/L, or at least 40.0, or at least 50.0.
  • the range of C OD content in the feed stream is typically between 20.0 g/L and 300 g/L.
  • Total gas in this context refers to the mixed product gas comprising both carbon dioxide and methane.
  • 25 C OD content is determined by the ferrous ammonium sulphate method well known in the art and is expressed in mg/L or g/L.
  • High C OD / high solids waste streams typically are associated with high content of undissolved solids.
  • a suitable bioreactor should typically be adapted to handle undissolved solids of at least 3.0 g/L, or 5.0, or 7.0, or 8.0, or 10.0, or 1 5.0, or 30 20.0, or 25.0, or 30.0, or 35.0, or 40.0, or 45.0, or 50.0, or 55.0, or 60.0.
  • One approach to handling anaerobic digestion of feed stream having a high content of undissolved solids in fixed film, fixed orientation, fixed bed systems is through the use of vertically oriented immobilization matrix. Undissolved solids in a vertically oriented matrix simply precipitate along the flow path. In some
  • sedimenting particles can be directed into sedimentation zones where particles can be collected harmlessly.
  • the invention provides fixed film, fixed orientation, fixed bed anaerobic digestion bioreactors comprising multiple compartments suitable for containing biofilm carrier matrix, each of which or most of which compartments is associated with a sedimentation zone.
  • “S edimentation zone” refers to a free volume situated between the bottom of the bioreactor tank and the lowermost edge of the carrier compartments, which are typically set significantly above the bottom of the tank.
  • tubular biofilm carriers are typically set within the carrier compartments such that the lower openings of the carriers are situated significantly above the lowermost edge of the carrier compartments.
  • the lowermost edge of the carrier compartments are typically set within the bioreactor tank significantly above the physical bottom of the tank - typically between 1 5 and 500 cm, or between 50 and 1000 cm, depending on the size of the digester.
  • a bioreactor of the invention is equipped with a digester bottom scraper device adapted to transport sediment formed in sedimentation zones at the bottom of the active digester volume into a sludge pump system. S ediments recovered from sedimentation zones can, in this manner, be reintroduced into the digester feed stream.
  • This serves to extend the exposure of undissolved solids to active biomethane-producing microbiology by separating the actual retention time of undissolved solids from the overall hydraulic retention time of the feed input.
  • undissolved solids that are precipitated from the feed stream can be recirculated without extending an otherwise short hydraulic retention time. This generally improves gas production and is in marked contrast with standard C ST R systems, in which hydraulic retention time applies to the entire feed stream, including dissolved and suspended solids.
  • F igure 1A shows one example of a bioreactor suitable for practicing methods of the invention.
  • the reactor is a 300 liter C ST R tank that has been retrofitted with a system of interconnected baffles that define internal biofilm carrier compartments. As shown, the tank is divided into compartments of equal height and
  • a cylindrical tank is fitted with internal compartments formed by corrosion resistant and liquid impermeable material baffle.
  • An inner section comprises 4 quarter-cylinder compartments having substantially equivalent cross sectional area.
  • An outer section comprises a curved outer wall that defines a cylindrical volume and trapezoidal compartments having one curved surface formed by the outer surface of a quarter-cylinder compartment from the inner section and having one curved surface formed by the curved outer wall of the outer section.
  • the compartments serve to contain porous, tubular biofilm carriers. In operation, the carriers are set at a level that is beneath the top wall and above the bottom wall of the compartments.
  • the bioreactor 40 has been retrofitted with a system of interconnected baffles 41 , 45, 46 that defines internal biofilm carrier compartments 42. As shown, the tank is divided into sections 43 of equal height and approximately equal cross sectional area.
  • a full baffle 45 has a height 80 of 54 cm
  • a low baffle 41 i.e. a baffle having an overflow aperture has a height 81 of 48 cm
  • a high baffle 46 i.e. a baffle having an underflow aperture has a height 82 of 51 cm.
  • the compartments 42 accommodate porous tubular biofilm carrier 44.
  • the porous tubular biofilm carrier 44 has a height 83 of 35 cm.
  • F igure 1 B shows an insert which advantageously may be fitted into the bioreactor 40 of fig. 1 A.
  • the disclosed insert comprising an outer tubular structure A1 having a longitudinal extension L.
  • the tubular structure A1 is typically made from a fluidic non-penetrable material thereby defining a continuously closed side wall.
  • the tubular structure has an opening (A2, A3) at each end of the outer tubular structure so as define an open compartment forming a flow passage inside the outer tubular structure extending between said openings.
  • one or more fluid penetrable biofilm carriers A4 is(are) arranged inside said outer tubular structure A1 .
  • the insert is preferably arranged with its longitudinal direction in vertical direction.
  • the insert may preferably arranged inside a tank reactor in a non-fixed manner to allow the insert to be taken out from the reactor. It is noted that non- fixed typically refer to a situation where in the insert is maintained in a certain position in manner allowing it to be removed without applying destructive procedures
  • F igure 1 C shows one embodiment of the insert according to one as pect of the invention.
  • F igure 1 C shows an insert for modifying a tank reactor 13, the insert comprising one baffle 1 defining two open compartments 2 and 3.
  • the baffle comprising has an open edge 21 define an underflow aperture 22.
  • a fluid introduced through an opening 32, such as an inlet is forced to flow downwardly towards and across the underflow aperture 22 and eventually upwardly towards an overflow aperture or a further opening 33, such as an outlet.
  • an insert as made in accordance with fig. 1 B does not comprise baffles inside the tubular structure.
  • baffles may be applied to the insert of fig. 1 B, although the purpose of such baffles may deviate as to not necessarily turning to flow inside the tubular structure. It is noted that when inserted into a reactor as shown in fig. 1 B, the baffles 41 and 46 may be disposed with.
  • F igure 1 D shows another embodiment of the insert according to one aspect of the invention.
  • F igure 1 D shows an insert 14 comprising two compartments 6 and 7 delimited by a continuous closed side wall 4, which is curved and surrounds the baffle 5.
  • the baffle 5 has an open edges 23 that is displaced in respect to a height 24 of the continuous closed side wall 4. When inserted into a reactor the flow follows the path as shown in figure 1 C .
  • F igure 1 E shows a further embodiment of the insert according to one aspect of the invention.
  • F igure 1 E shows an insert 15 comprising two baffles 1 1 and 12 and three open compartments 8, 9 and 10.
  • the open edges 25 and 26 of the two baffles 1 1 and 12 are displaced in respect to each other so that when a fluid is flowing through the insert it will flow through the underflow aperture defined by open edge 25 and towards and through the overflow aperture defined by open edge 26.
  • F igure 2A shows a bioreactor similar to that shown in F igure 1 A, but with more detailed features.
  • the digester is arranged in four quarter sections, in which each quarter-cylinder compartment of the inner section is associated with three trapezoidal compartments of the outer section.
  • T his scheme is advantageous because it is simple to assemble as an insert that can then be fitted into a larger tank, such as a C ST R tank.
  • the compartments of the outer section become trapezoidal simply as a consequence of the geometry of the quarter-section and the division of the outer section into three compartments.
  • one or more additional outer section(s) could be included having, additional compartments.
  • F igure 2B shows the bioreactor 47 that is the bioreactor of figure 2A.
  • the bioreactor 47 is arranged in four quarter sections 48, in which each quarter- cylinder compartment of the inner sections 49 is associated with three trapezoidal compartments 50 of the outer section.
  • S crapers 54 prevents or reduces short circuiting between neighbouring sections. S craper in section sealing position ensures no passing of liquid or reduces passage of fluids between sections even though sedimentation s pace is shared. S edimentation zones 55 are located at the bottom of the bioreactor 47.
  • F igure 2C shows section of an insert according to some embodiments of the invention.
  • F igure 2C shows a section of an insert 20 having interconnected baffles 1 6,17,1 8 and 1 9.
  • the baffles are a full baffle 16, two low baffles 17 and 1 8 and a high baffle 19.
  • the insert 20 has an inner or internal section 27 and an outer or external section 28.
  • the outer section 28 comprises three open compartments 29, 20 and 31 , in between baffles 1 6 and 18 and defined by baffles 17 and 1 9.
  • the insert 20 forces a fluid inserted, according to the direction of arrow 36, in section 27 to flow downwardly towards the underflow aperture leading to compartment 29 and then upwardly towards the overflow aperture leading to compartment 30.
  • the fluid flows downwardly towards the underflow aperture leading to compartment 31 and upwardly according to the direction of arrows 34 and 35 back into sections 27 or out of the section and ins ert according to the direction of arrow 35.
  • Fizid flow is directed sequentially through succeeding carrier compartments within each quarter section by a system of overflow and underflow apertures.
  • Re- circulation suction pumps are provided for each quarter section. The pumps are adapted to withdraw fluid from the top of the last compartment within the flow sequence of a quarter section, in which the vertical direction of flow is upward. This removed fluid is then re-introduced to the first compartment within the flow sequence of the quarter section.
  • the recirculation flow can be introduced from above the surface of liquid in this compartment, thereby actively enhancing mixing in the chamber to which the recirculation flow is introduced. Influent feed stream is mixed with recirculation flow. This in turn drives fluid flow through the reactor - the net volume of feed stream introduced drives net flow through the reactor.
  • a feed inlet introduces feed stream mixed with recirculating effluent into one quarter-cylinder compartment of the inner section.
  • the curved wall of this compartment is shortened at the bottom, providing an opening for fluid flow into the bottom of a first trapezoidal compartment of the outer section.
  • This shortened wall is one means for achieving an underflow aperture, meaning an opening at the bottom of the compartment that permits fluid flow into a succeeding compartment.
  • S imilarly a shortened wall at the top of a compartment is one means for achieving an overflow aperture whereby fluid flow is directed into succeeding compartments.
  • Underflow or overflow apertures may alternatively be simply an opening in an otherwise intact wall. However, this arrangement increases the risk of channelling.
  • tubular biofilm carriers are typically set in compartments at a level such that the lowermost openings of the tubular carriers are at a height above the underflow aperture (i.e. above the lowermost surface of the shortened wall at the bottom) corresponding to between 2-10 times the diameter of the carriers' primary fluid channel.
  • the uppermost openings of the tubular carriers are at a height below the overflow aperture (i.e. below the uppermost surface of the shortened wall at the top) corresponding to between 2-10 times the diameter of the carriers' primary fluid channel.
  • the physical carrier compartments themselves are set within the bioreactor tank at a level such that the lowermost edge of the compartments is above the physical bottom of the bioreactor tank.
  • the open volume beneath the lowermost edge of the carrier compartments defines a sedimentation zone in which sedimenting particles can accumulate.
  • the embodiment shown in F igure 2A is further equipped with a rotable scraper having four arms, each of which arms, in the closed position, makes a fluid tight seal between two quarter-sections of the cylindrical tank by sealing the gap between the lowermost edge of the carrier compartments and the bottom of the tank. This fluid tight seal ensures that fluids within the sedimentation zone will not flow laterally between quarter sections of the reactor.
  • the rotable scraper can be used periodically to force sediment into a sediment outlet from which it can be pumped and recirculated into the feed stream.
  • F eed stream mixed with recirculated liquid enters a first compartment of the inner section, travels in a downward vertical direction through biofilm carriers, then passes through the underflow aperture into a trapezoidal compartment of the outer section.
  • the fluid flow through biofilm carriers in the second compa rtment is forced into an upward vertical direction.
  • the fluid flow passes through an overflow aperture into a third compartment.
  • the fluid flow is forced to change vertical direction into a downward vertical flow through the third compartment.
  • the flow is forced into a pattern of alternating downward and upward direction and routed sequentially through each compartment of the reactor until it reaches the last compartment of the sequence, which is fitted with an effluent outlet that is situated at a level intermediate between the top surface of the compartments and the level corresponding to the bottom of the overflow apertures, i.e. the uppermost surfaces of the shortened walls at the top of compartments.
  • This ensures that effluent will be driven out by force of gravity.
  • the flow within each quarter section is continuously recirculated. The volume of feed stream introduced ensures that there will be net displacement sequentially between the quarter sections and out through the effluent outlet, notwithstanding continuous recirculation within each quarter section.
  • T he region beneath the lowermost openings of the biofilm carriers at the bottom of two compartments which are in fluid communication via an underflow aperture provides a mixing zone.
  • the region above the uppermost openings of the biofilm carriers at the top of two compa rtments which are in fluid communication via an overflow aperture similarly defines a mixing zone.
  • mixing is achieved within the mixing zones during operation by the forced change of vertical direction of flow from downward to upward. Because fluid flow through the reactor is achieved without agitation, the flow through the tubular biofilm carriers is substantially laminar. F urthermore, without agitation, undissolved particles will precipitate down the tubular biofilm carriers' primary, vertical fluid channel and into the sedimentation zones.
  • a downwa rd vertical flow is directed through a first compartment in the quarter section (b), passing through tubular biofilm carriers as a plug-flow.
  • S ediments form in a sedimentation zone that has a shared open volume for all compartments of the section.
  • a sludge scraper blade (d) seals the volume between the lowermost edge of the carrier compartment and the bottom of the tank, preventing fluid from flowing a long the bottom between qua rter-sections of the bioreactor tank. Downward flow through the first
  • compa rtment is changed into an upward vertical flow through the second compa rtment.
  • An underflow aperture is provided by a shortened wall at the bottom of the first and second compartments.
  • a mixing zone is provided in the open volume beneath the lower openings of the tubular biofilm carriers. S uction action of recirculation pumps situated in the last chamber in the flow sequence of the section serve to draw flow. A gentle mixing is accomplished in the mixing region at the bottom.
  • U pward vertical flow through the second compa rtment is changed into a downward vertical flow through the third compartment.
  • An overflow aperture is provided by a shortened wall at the top of the second and third compartments.
  • a mixing zone is provided in the open volume above the upper openings of the tubular biofilm carriers.
  • a downward vertical flow is directed through a first compartment in the quarter section 56, passing through tubular biofilm carriers 57 as a plug-flow.
  • S ediments form in a sedimentation zone that has a shared open volume for all compartments of the section.
  • a sludge scraper blade 58 seals the volume between the lowermost edge of the carrier compartment and the bottom of the tank, preventing fluid or reducing fluid from flowing along the bottom between quarter-sections of the bioreactor tank.
  • F igure 4 shows a schematic illustration of fluid flow patterns, through alternating underflow and overflow apertures (i.e., in alternating upward and downward vertical flow) between carrier compartments of the bioreactor described in F igure 2A and for a similar bioreactor scaled to 1000 m 3 size.
  • the top view shows the chamber distribution, the flow pattern with over- and underflow and the circulation flow direction and placement.
  • Both examples are C ST R tanks fitted with an insert of the invention in which the carrier compartments are filled with tubular biofilm carriers.
  • FIG 4 the flow is shown as overflow according to arrow 59, as underflow according to arrow 60 and as circulation direction and placement according to arrow 61 for two different type of reactors, being 62 a FAD 0.3 m 3 and 63 an FAD 1000 m 3 .
  • a 1000m3 FAD can be designed with only 1 6 chambers like the pilot scale FAD. In the 2A drawing there are 32 chambers. Applying 1 6 chambers to a 1 .000m3 FAD gives a circulation pump flow of 35m3/h which is found to be acceptable.
  • liquid flow through the upper mixing zones is defined by the walls of carrier compartments being higher than the liquid surface.
  • Liquid flow through the lower mixing zones is not limited by compartment walls or baffles. Instead, liquid flowing out of one compartment at the bottom will be sucked into the up-going flow through the next compartment.
  • the sedimentation zone underneath the lowermost edge of the carrier compartments is one shared volume between the lowermost edge of the carrier compartments and the digester tank bottom, from the lowest chamber walls to the digester tank bottom. Liquid flow leaving the biofilm carriers in the first compartment in the flow sequence of a quarter-section will travel towards the digester tank bottom. As suction in the second compartment in the flow sequence removes liquid beneath the biofilm carriers in the second
  • the liquid entering a biofilm carrier in the second compartment will have been mixed between the exit from the first compartment to the entrance to the second compartment.
  • the sedimenting particles that do not follow the liquid flow through the compartment will be allowed to collect at the tank bottom until the digester bottom scraper transport them to sediment removal.
  • the carrier matrix used to support biofilm in a fixed film, fixed orientation, fixed bed system is ideally tubular and porous.
  • tubular refers to a structure that defines one or more central channels through which fluid will flow in one direction by the force of gravity when it is placed in an upright, vertical orientation.
  • a tubular matrix can have one or more central channels having an irregular, rectangular or even triangular cross sectional geometry.
  • tubular matrix is preferably cylindrical, that is, having one or more central channels having a circular cross sectional geometry. Cylindrical geometry is preferable because the presence of corners in the fluid channel creates pockets of restricted flow. This in turn tends to promote
  • the biofilm carrier matrix is preferably porous.
  • porous refers to a carrier matrix having openings on the channel-forming surface which may be openings formed between twisting and evaginated surfaces.
  • a smooth surface matrix for example, the CLOISONYLTM tubes used by Escudie et al. (201 1), permit only one possible "direction" for biomass accumulation in the biofilm - towards occlusion of the biofilm carrier's fluid channels.
  • porous matrix provides multiple "directions" for biomass accumulation in the biofilm, and tends to promote growth in a thinner film in which surface area to volume ratio of the film is maximized.
  • F igure 5A shows the smooth surfaced biofilm carrier versus threaded, corrugated biofilm carrier, wherein the smooth surface biofilm carrier 64 carries a vulnerable biofilm 65 attached to the smooth surface, i.e. the biofilm 65 can be easily torn off.
  • the porous biofilm carrier 66 has carrier walls 67 consisting of threaded material.
  • the biofilm 68 attaches to all surfaces of the threads. If the biofilm pointing inwards in the tube is torn, the biofilm attached to the other dimensions of the thread remains attached, thus being able to regenerate the biofilm washed away.
  • a porous biofilm carrier matrix has a total surface area to volume ratio of between 60 m 2 / m 3 and 300 m 2 /m 3 , or between 80 and 200, or between 90 and 150.
  • the total surface area to volume ratio of the carrier matrix is defined by the nominal total volume of the channel-forming matrix, as defined by its outer-most boundaries, and by the exposed surface area of the matrix prior to biofilm accumulation.
  • the central channel of a porous biofilm carrier matrix as a percentage of cross-sectional area prior to biofilm accumulation is between 40% and 80%, or between 50% and 70%, or between 60% and 65%.
  • the percentage of void volume of the total volume of a porous biofilm carrier matrix is between 50% and 90%, or between 60% and 88%, or between 72% and 82%.
  • the tube diameter of a porous, cylindrical biofilm carrier matrix is between 0.030 m and 0.080 m, or between 0.036 and 0.070, or between 0.04 and 0.055.
  • material for use as immobilization matrix may include polyethylene, polypropylene, nylon, ceramics and most other materials that are resistant to acid and alkali corrosion and that will allow for bacterial exopolymer to attach to the carrier.
  • a matrix comprising netting is used in which the netting is formed into a tube and in which the netting defines the outer periphery of the total volume.
  • the netting is formed by intertwined, extruded polyethylene threads having surface roughness. The roughness of carrier threads promotes microbial adherence as it presents small crevices and holes in which microbes may attach. Netting also renders biofilm resilient to d is -attachment by ordinary shear forces compared with a biofilm carrier having a smooth surface. Where the biofilm carrier is formed from rough netting, high flow velocity is less likely to increase risk of biofilm disruption, and the related risk of clogging.
  • One suitable, commercially available material for use as biofilm carrier formed by netting are the various forms of BIO BLOKTM provided by EXPO NETTM,
  • BIO BLOK 80TM BIO BLOK 100TM
  • BIO BLOK 150TM BIO BLOK 200 5 TM
  • BIO BLOK 300TM BIO BLOK 300TM.
  • S uch Bio Bloks has a tube diameter as disclosed in hnp;// w ,expO"
  • S uch diameter may be in the ranges of 25mm - 100mm such as in the range of 35 mm - 70 mm, preferably in the ranges of 40 - 60 mm.
  • Methods of the invention are practiced using a plurality of vertically oriented, porous, tubular carriers supporting biofilm.
  • start-up and initiation procedures known in the art may be used, including but not limited to those described by Hickey et al. 1 991 .
  • C ell density of microorganisms within a biofilm formed on a carrier can typically reach levels one order of magnitude higher than can be achieved in C ST R liquid volumes.
  • 20 VFA is at least 20g/L in the start-up feed stream. It is further advantageous to use a high C OD organic load in the start-up feed stream, wherein total C OD is at least 30g/L, or between 35 - 15o g/L, and wherein organic load is taken to levels of at least 50g/L digester volume/day.
  • the biofilm advantageously has a relative proportion of methanogenic Archaea relative to bacteria of at least 25%, or at least
  • the relative proportion of Archaea to bacteria in the biofilm is determined in a biofilm sample by comparing the products from 16srR NA polymerase chain reaction (PC R) using universalis rR NA and Archaea-specific 1 6s rR NA primers reported by Gantner et al. (201 1 ) in a DG G E gel.
  • PC R polymerase chain reaction
  • mixing zones both above the upper openings and below the lower openings of the carriers, where “openings” refers to the central channel through which fluid flow emerges at the bottom surface of the tubular structure which defines the channel.
  • Mating zone refers to an open volume in which mixing can be achieved outside the carrier channel volume in which fluid flow should be substantially laminar and, thus, substantially unmixed, except for some back-mixing at the biofilm surface.
  • F low is said to be substantially laminar where the corresponding Reynolds number is 3200 or lower.
  • Reynolds number is a dimensionless parameter used to predict flow patterns within defined physical constraints.
  • Reynolds number is calculated from a ratio of inertial forces to viscous forces under defined flow conditions.
  • the Reynolds number is defined as Q*Dh / vA, where Q refers to volumetric flow in m 3 /s, Dh refers to the hydraulic diameter, meaning the effective internal diameter of the channel defined by the tubular carrier, v is the kinematic viscosity in m 2 /s (calculated as the ratio of the fluid viscosity in kg/m*s to its density in kg/m 3 ), and A is the effective cross- sectional area of the internal diameter of the channel in meters (m).
  • F low is said to be substantially laminar meaning that the flow pattern is expected to be laminar, however, some back mixing may occur as a consequence of biogas production or for other reasons.
  • the total carrier cross sectional area will be limited by the chamber dimensions.
  • F low velocities through systems of the invention are determined by inter-relationships between dimensions of the carrier compartments and capacity of circulation pumps. Bioreactors of the invention typically permit one circulation pump to circulate many compartments. As digester size and digesting capacity increase, the number of carrier compartments increases.
  • control of flow through a bioreactor of the invention can be described as follows.
  • each of the four quarter-sections of the FAD bioreactor is circulated by a circulation pump.
  • the circulation system thus comprises 4 equivalent liquid circulation pumps which control circulation between carrier compartments within a quarter-section.
  • C irculation serves two purposes; securing the correct flow velocity through the biofilm carriers and re-introducing biomass that has just passed through one carrier compartment into the next compartment in sequence at an adequate frequency.
  • the principle is that each time the digester volume is split into two equal volumes by means of a vertical fluid barrier, the flow velocity in each half of the digester volume will be doubled relative to the flow velocity in the undivided digester volume, provided that the flow is forced to travel along the vertical height of both halves.
  • the circulation pump flow in each section is then X times faster than the overall circulation flow through the digester. This enables both the design of a specific flow velocity through each chamber and limits the necessary circulation pump capacity.
  • the capacity of the circulation pumps should ideally be enough to re-introduce the circulation flow into each of the carrier compartments within a quarter-section at least two times per hour. In some embodiments, capacity of recirculation pumps is sufficient to re-introduce circulation flow into each of the carrier compartments within a quarter-section between 2 and 30 times per hour, or between 3 and 20.
  • the required flow velocity and the minimum volume re-introduction requirement define the maximum and minimum circulation pump capacity for any given size of FAD digester. As the feed flow is introduced into one or more of the four quarter- section circulation streams, the feed flow contributes to the overall biofilm carrier flow velocity and should generally be taken into consideration when determining the correct circulation pump flow capacity.
  • C ST R tank Any size and type of C ST R tank can be fitted with an insert to make a bioreactor of the invention.
  • the dimensions, circulation flows and chamber arrangement will differ and can be adapted to each tank type as described in Table 1 . It will be readily understood by one skilled in the art that other schemes for compartmentalization may be used in addition to the quarter-section scheme of embodiments shown in F igure 2A and F igure 4.
  • the flowing fluid should ideally be mixed when passing from one compartment to another.
  • the direction of vertical fluid flow through biofilm carriers alternates between succeeding biofilm carrier compartments between "down” and “up.”
  • the liquid passing through the biofilm carrier in an up/down direction will be transferred to the next compartment via a horizontal movement.
  • the flow will be forced sideways through the sedimentation zone to the volume under the succeeding biofilm carrier chamber.
  • the sideways movement of the flow which - until this point has been vertical - achieves a gentle mixing of the liquid prior to its being forced upwards in a plug-flow through a biofilm carrier in a succeeding biofilm carrier chamber.
  • Mixing is achieved in mixing zones, and can be accomplished by a variety of different means.
  • sedimentation zones are themselves mixing zones.
  • mixing may be achieved by a mixing pump or an agitator.
  • mixing in some compartments of a bioreactor may be achieved by introducing a feed stream and/or recirculation stream from above the fluid surface, thereby achieving a splashing mixing effect.
  • mixing is achieved simply by forcing the fluid flow into a volume from which it is forced to change its direction of vertical flow.
  • Anaerobic digestion is conducted by means well known in the art, but informed by new results presented here.
  • F urther, and surprisingly, the operation temperature is in fact readily changeable, notwithstanding prevailing prior belief that anaerobic digestion microbes cannot simply be rapidly shifted from mesophilic ( 35-42 oC) to thermophilic (49-55oC) conditions.
  • the high solids feed stream is typically processed within a short hydraulic retention time (H RT), 120 hours or less, or 100 hours or less, or 75 hours or less.
  • H RT hydraulic retention time
  • F urther to maintain high total gas production, an appropriately fast flow velocity is maintained.
  • F low velocity refers to the linear velocity of fluid flow through the tubular biofilm carriers, expressed in meters/second (m/s). F low velocity can be controlled by a variety of means, as will be readily understood by one skilled in the art. In some embodiments, flow velocity is controlled by the total influent input including both feed stream and recirculation.
  • flow velocity can be approximated as follows: (1 /3600 seconds/hour)*[total input in liters/hour (including feed stream input and recirculation stream) / total digester usable internal volume in liters (which is defined by the total volume of liquid in the digester tank minus the net volume displacement of liquid by the tubular carriers)] *(height of the liquid column in the digester in m) *(total number of biofilm carrier compartments in the digester).
  • flow velocity should be maintained at least at 0.0002 m/s or higher. In a 1000 m 3 commercial scale reactor, flow velocity should be maintained at much higher rates at least 0.020 m/s. Typically, flow velocity should be maintained within the range 0.0002 m/s to 0.08 m/s, or between 0.0030 and 0.07, or between 0.009 and 0.05.
  • Other embodiments of a bioreactor of the invention may have other shapes of digester chambers.
  • One such alternative chamber shape could be rectangular shaped chambers, round chambers, hexagonal or octagonal chambers.
  • the chambers can take on any shape that both allow for the chambers to occupy the whole of the digester cross section area and prevent sharp flow-slowing corners.
  • S ediment typically has between 12-1 5% by weight dry matter (or may have a higher or lower content), where "dry matter” refers to total solids, and typically comprises a substantial component of biologically inert, i.e. undigestible, C OD and inorganic dry matter, primarily inorganics that were freed from the feed stream biomass during digestion.
  • dry matter refers to total solids, and typically comprises a substantial component of biologically inert, i.e. undigestible, C OD and inorganic dry matter, primarily inorganics that were freed from the feed stream biomass during digestion.
  • S ediment obtained from such systems typically offers good fertilising power in that it contains most of the phosphorous content from the feed stream as well as a high concentration of nitrogen-containing compounds and nutrient salts.
  • sediment obtained from such systems can have between 30 - 50% dry matter, which reduces handling costs when the material is discarded, transported for use as fertiliser or
  • a smaller, simpler version of a reactor suitable for practicing methods of the invention can be used as a laboratory scale device for rapid determination of biomethane potential of tested substrates. It is generally accepted by those skilled in the art that biomethane potentials determined in 20-week long laboratory batch tests inevitably overestimate the yields that can actually be achieved in a commercial scale C ST R system. Typically these laboratory figures are deflated by 20% in calculation of commercial expectations. In contrast with batch C ST R tests, however, the fixed film, fixed orientation, fixed bed systems of the invention provide biomethane potential estimates on laboratory scale that very nearly approximate the yields that can be achieved using these systems in commercial scale. Moreover, unlike C ST R batch tests, which are time consuming, biomethane potential tests using systems of the invention can deliver accurate measurements within a single week.
  • F igure 6 and F igure 7 show schematic illustrations of two embodiments of a laboratory scale test device.
  • the reactor shown in F igure 6 is a single cylindrical tank 70 with mixing zones above and below vertically oriented tubular biofilm carriers 71 . E ach of the mixing zones is agitated by a rotor 69 having blades 72. The liquid content of the tank are continuously recirculated according to the circulation flow 73. Influent feed is mixed with recirculated liquid. The net volume of added feed determines net displacement of effluent from the system.
  • the reactor shown in F igure 7 is somewhat more complex in that three individual reactors of the type shown in F igure 6 are combined in series.
  • figure 7 shows a bench-scale FAD digester in series resembling three FAD chambers.
  • the liquid content of each of the tanks is continuously recirculated.
  • the net volume of added feed determines net displacement from the first tank to the second and from the second tank to the third to effluent.
  • the bulk of anaerobic digestion occurs in the first tank, but good finishing is achieved in later tanks in the series. This generally mimics the circumstances of a commercial scale plant.
  • FIG 7 shows a system for producing biogas (74), the system comprising: at least one feed tank (75) for feeding bioreactors; one or more interconnected bioreactors (77); at least one effluent tank (76) for collecting effluents from the one or more interconnected bioreactors.
  • a 30 L biogas bioreactor system termed "Fast Anaerobic Digestion (FAD)" system was designed comprising a feed tank, three consecutive anaerobic digesters and an effluent tank.
  • FAD Fluorobic Digestion
  • E ach of the three consecutive digester tanks was equipped with non-random vertically oriented tubular bacteria carriers, BIO BLOK 300 Tm, on which an anaerobic biofilm was attached that conducts anaerobic degradation of organic biomass and subsequent conversion into biogas.
  • E ach of the three consecutive digesters had a total liquid volume of 10 L and 6 L of this volume was occupied by biofilm carriers.
  • E ach of the three consecutive digesters was 20cm wide.
  • E ach of the tubular carriers inside is 20cm long had an open end diameter of 22mm and an outer carrier diameter of 32mm.
  • the digesters were filled with liquid. Over and under the biofilm carriers were app. 5 cm free liquid. E ach of the three digesters was equipped with central-shaft mounted propeller agitators in the carrier free liquid over and unde r the biofilm carriers. Inner diameter of the primary fluid channel defined by the tubular carriers in the absence of biofilm was 2,2 cm.
  • the three digesters were mounted at different vertical positions with the first digester mounted highest, the next consecutive digester 25cm lower than the first digester and the last consecutive digester mounted 25cm lower than the second digester.
  • the differences in vertical mounting height allowed for liquid to flow from the first digester to the second and third by gravity.
  • the liquid level in all three digesters was defined by an effluent pipe above the carriers. When new feed enters the first and highest mounted digester the level in this digester will rise over the effluent pipe level and the excess liquid will leave the digester to enter the second digester which will then experience level elevation and the excess liquid from this digester will then flow to the third and last consecutive digester. F rom this digester, the excess liquid will flow out of the effluent pipe of the third digester into an effluent holder.
  • All three digesters have circulation effluent tubes in the bottom of the digester. F rom the effluent pipe, the digester content is continuously sucked into a peristaltic circulation pump and returned to the digester through a digester top circulation liquid inlet pipe.
  • the circulation flow rate was defined by the wanted flow velocity through the open diameter of the vertically oriented biofilm carriers. T he circulating liquid was mixed by the propeller over the biofilm carrier before the liquid flow enters the carrier body through which the flow is a laminar plug-flow. When the circulating liquid leaves the carrier zone it was again be mixed by the agitator propeller under the carriers before repeating the circulating cycle.
  • the internal circulation flow may have at least two functions:
  • T he system was operated automatically with pulse-pause a nd speed control on both feed pump and circulation pumps. pH, digester temperature and gas flow were measured and logged on-line and could be accessed and controlled remotely. pH, temperature and gas flows along with analysis measurements of VFA(Volatile Fatty Acids), C OD(C hemical Oxygen Demand), Nitrogen and cations were used to monitor system health and provide data for test purposes.
  • VFA Volatile Fatty Acids
  • C OD C hemical Oxygen Demand
  • Nitrogen and cations were used to monitor system health and provide data for test purposes.
  • the RT D analysis provides a mathematical, graphical and vessel wise picture of fluid and particle distribution in the system. F or optimum mixing, the total system behaves like a true plug-flow, and each digester as a C ST R notwithstanding, there are plug-flow zones in each digester. If RT D analysis shows that mixing is not optimal, it should point towards an optimal solution.
  • the reactors were visually inspected for proper functioning and each of them was filled with 7.5 liters of tap water.
  • T was injected with a single dose of methylene blue to a final concentration of 0.0058mM and the absorbance was recorded using a spectrophotometer set at 668nm (wavelength where methylene blue displays maximum absorption).
  • a constant flow of water was then introduced to the first reactor in series using a peristaltic pump and from the top, in order to have an entire volume displacement inside the reactor in a lapse of 2 hours. During this process, every 5 minutes a sample is taken from the top of each individual reactor and measured in the spectrophotometer.
  • the RT D curve was then plotted to verify if the system has a proper mixing and if the flow occurred as intended.
  • R esults were compared with similar experiments in literature.
  • the circulation speed was set to 0.45 per Minute.
  • F igure 8 shows an ideal behaviour of a cascade of C ST R reactors when there is proper mixing of the solution inside all the digesters.
  • the experimental results from this RT D analysis are shown in F igure 9.
  • the comparison of ideal and empirical graphs showed that flow behaviour of the system was adequate.
  • the maximum concentrations or peaks of individual digesters occurred when these overlap the previous, indicating there is a gradual increment of the total cascade volume; as expected in a well-mixed system.
  • F urthermore after time 60 min, the concentration of dye in all the digesters slowly decrease in the expected order and this indicates that the flow from the first to the last digester is adequate as the dye does not concentrate in any specific area of any digester of the system.
  • the best match of microbial composition will be from anaerobic digesters converting a biomass similar to the biomass expected in the fully loaded FAD digester.
  • FAD is expected to operate on enzymatically and microbially pre- digested (liquefied) organic fraction of municipal solid waste(MSW) and as no such digester exist, the closest are digesters operated on other types of pre- digested biomass.
  • MSW microbially pre- digested
  • biogas digester was selected as a source of seed inoculum since this operates on source separated food waste.
  • Most human consumables have been pre-processed and consist mostly of carbohydrates, fat and meat proteins. This was the closest match to the liquefied organic fraction of municipal solid waste (MSW) that will present the highest concentration of the required microbial consortia.
  • the methanogens When taken out and transported, the methanogens can be expected to stress and become temporarily inactive.
  • the FAD digesters were left standing for 7 days at an operation temperature of 37 eC
  • a pulse shock load of 1 50ml of liquefied organic fraction (LOF) of MSW (S LR of 0,6 gC OD/L*d) were injected into all digesters to test their own and their readiness for beginning the load-up.
  • the 1 50ml LOF was well under the usual load per day for the digester content of the Billund Biogas digester and did not present any danger of overfeeding the inoculum bacteria.
  • the resulting gas and a C OD balance analysis indicated that the expected amount of biogas had been produced. When this digester "health" check was approved and the expected conversion rate had been shown for all the digesters, the digesters were ready for load-up.
  • the starting load was determined.
  • the digester content cannot be expected to exert the same efficiency as it did inside the source digester.
  • the Billund Biogas informed about the normal C OD load in their digester being app. 3 gC OD/L ⁇ d, and the starting load of LO F in the FAD bench scale system was determined to be 2/3'rds (2gCOD/L*d) for this flow to both gain a fast load-up and respect any process difficulties originating from the transfer to the FAD digesters.
  • the biofilm was expected to attach to the carrier and encompass the wanted microbes within a time frame of 8 - 12 weeks (as known in the art).
  • the sequence will be firstly attachment of different exopolymer excreting rods and cocci followed by a diverse consortium of bacteria families over 5-7 weeks and only followed by methanogenic Archaea during the 10'th to 12'th week of the biofilm inoculation.
  • the biofilm carriers were at all times covered by digester liquid, the biofilm itself could not be directly monitored.
  • the digester liquid was able to convert the fed-in C OD like any C ST R digester.
  • the digester system will be loaded up in the same way a conventional biogas system is loaded up with the C OD load increase respecting the growth limitation on the slowest growing microbes - the methanogens.
  • the load-up is performed at an feed-in increase of app. 1 ,5% per day based on the feed-in during the preceding day.
  • the methanogen maintenance time of 10-14 days was respected.
  • Total volatile fatty acids in particular acetate and lactate, have already been fermented during enzymatic and microbial liquefaction of the organic fraction of municipal solid waste .
  • the total and volatile solids of this LOF feed typically can oscillate between 100-120 gr solids/L and 80-100 gr/L respectively. Total solids is expressed as a percentage w/w.
  • F igure 10 shows gas production (diamonds) and feed rate (circles) in liters per day over the course of 95 days biofilm build-up of the FAD system described in example 1 using the LOF feed described in Table 2.
  • F igure 1 1 shows C OD removal in % total (squares) and hydraulic retention time (triangles) over the course of 1 00 days biofilm build-up of the FAD system described in example 1 using the LOF feed described in Table 2.
  • the LOF feed used in biofilm buildup this point was initially reached at 72 hours hydraulic retention time. However, this was not believed to reflect any underlying metabolic limit of the system but rather technical difficulties arising from pH balance issue using the highly acidic feed.
  • the inside of the tubular carrier looks the same.
  • the biofilm attached to the carrier comprises a greenish, slippery material and generally exhibits a thickness of between 0,5 - 1 ,5 mm depending on whether the biofilm is growing on the thread surfaces pointing into the tube centre (thinnest biofilm) or growing in the space formed by the overlaying threads making up the carrier (thickest biofilm).
  • the biofilm is evenly distributed over all carrier threads.
  • the biofilm is smooth and does not exhibit any threads protruding out from its surface.
  • biopsies of the carrier have been taken from the digesters.
  • the biofilm seems to be easily removable from the carrier by means of high velocity water flushing, etc. When removing the biofilm from the carrier, the biofilm does not loosen in layers but only the film at the shear force point will rub off.
  • C ell density of microorganisms within a biofilm formed on a carrier can typically reach levels one order of magnitude higher than can be achieved in C ST R liquid volumes.
  • high density of methane producing Archaea within biofilm formed on porous tubular carriers in practicing methods of the invention contributes to increased biogas production performance using bioreactors of the invention. Maintaining high cell densities within the biofilm serves to protects the microbial community from process imbalances that would affect a C ST R system.
  • F urthermore the high organic loads used during the reactor's seeding favours the attachment of dense microbial communities to the biofilm with even higher cellular ratios than at lower organic loads.
  • the relative percentage of Archaea to bacteria and approximate cell densities within biofilm removed from "biopsies” as described can be determined by comparing the products from 1 6srR NA polymerase chain reaction (PC R) using universalis rR NA and Archaea-specific 1 6s rR NA primers reported by Gantner et al. (201 1 ) in a DGG E gel.
  • PC R polymerase chain reaction
  • the first digester chamber of the cascade is expected to have a higher ratio of Archaea than in the subsequent chambers since most of the easily degradable metabolized organics are converted by microbes preferring monomeric sugars, low molecular lipids, etc. in this process step.
  • subsequent digester chambers comprise communities more specialized in degrading larger organic compounds that are converted into biogas.
  • Biofilm in the digesters was developed using LOF feed at mesophilic temperature - 37 eC .
  • the temperature was subsequently raised to 52 eC over a very short period of time. This resulted in faster C OD turnover and elimination of the need for pH adjustment of the acidic LOF feed.
  • the active biology, immobilized in the biofilm cannot change very rapidly.
  • bioreactors of the invention can operate in either temperature range regardless of the initial load-up temperature.
  • the system was fed with a consta nt feed rate of acidic LOF feed at 53oC until stable gas production was achieved. Temperature of the system at constant feed rate was suddenly changed to 37oC and maintained until stable gas production was again achieved. The temperature was then restored to 53o C and maintained until stable gas production was again achieved.
  • the FAD system developed as described in examples 1 , 3 and 4 was fed with an LOF feedstock having the characteristics shown in Table 3 with a hydraulic retention time of 91 hours for a period of 52 days.
  • F igure 14 shows gas production (red circles) and feed rate(blue circles) for 48 days.
  • F igure 1 5 shows C OD conversion % over a period of 48 days.
  • F igure 1 6 shows C OD content (circles) and V FA levels (triangles) measured in effluent from the digester system for 51 days.
  • the system supports stable operation with minimal need for process controls. S uch a stable operation is very beneficial in terms of the determination of both the biomass gas potential and gas production under continuous conditions.
  • the C OD conversion efficiency preserved regardless of the feed-rate and the gas production becoming stable with the feed-in stabilises it is a very strong indicator of the real gas production under continuous conditions.
  • the total gas production from the first feed-in to the gas production seizes after removal of the feed will show the gas potential of the feed material just as good as if it was performed in a regular batch-test.
  • VFAs volatile fatty acid
  • F igure 17 shows VFA concentration (circles) and conversion efficiency (squares) measured within a single digester chamber over the course of 25 days. As shown, the high VFA concentrations are clearly not inhibitory and C OD conversion efficiency is not correlated with the measured VFA concentration variation. Thus, the maximal acceptable VFA concentration in the FAD system lies higher than the measured maximal concentration of 16,2 g VFA/L.
  • Line 402 shows the F eed in; line 401 the gas produced.
  • F igure 12 shows biogas production and feed rate during different phases of this experiment, which consist in a Load-up, Stable feed-in and gas production and Burn-down (expression of the remaining gas production after feed- in seizure) of the remaining organics of the two different substrates.
  • the Load-up periods A1 and A2 consist in a two day operation in which the reactors are fed with increasing amount of substrate up to the stable production load, respectively B1 and B2.
  • F or the first substrate the average biogas production was 88,08 NL/day, with a methane content of 61 .8% for an average of 54,44 I C H4/day. This is equivalent to a 80% C OD conversion efficiency.
  • the liquid inside the reactor was entirely removed through the recirculation escape in the digester bottom.
  • the digester was then flushed with an amount of tap water (at room temperature) equivalent to twice the volume of the digester.
  • the carriers remained exposed to atmospheric oxygen for 3 days, after which the reactor was filled again with an effluent from a previous experiment, similar to that removed before the air exposure.
  • the system described in examples 1 , 3 and 4 was fed with a variety of different feedstocks.
  • the system in claim is flexible for operation with high gas production at high organic loading rates with different feedstock.
  • the system has been in continuous operation at lower HT R than 5 days with dissimilar feedstock composed by different sugars, volatile fatty acids and ethanol that can be metabolically transformed in anaerobic digestion processes.
  • the feed-in of the reactor system has been performed continuously alternating among the different feedstock and therefore different organic loading.
  • the productivity of the digester reflecs a rapid adaptation to the newly introduced feedstock as the produced biogas following the change corresponds to the potential of each feedstock that had been previously determined. Thin stillage
  • Thin stillage is a waste water fraction originating from the 2G bioethanol production. Thin stillage is free of large particles as the lignin containing particles have been separated to be used elsewhere. The thin stillage contains mainly oligomering sugars that is challenging for the biogas process as it requires a high hydrolysing power to degrade the oligomers. As it shows in F igure 19 the FAD digester started up on LOF feed comprising predominantly monomeric sugars, fat and short lipids can easily cope with the more complex lignocellulos ic Thin stillage having the characteristics shown in Table 4 comprising heavy degradable oligomeric sugars, lignin derivatives and very little lipids and proteins. Both R E nescience bioliquid and Thin stillage have in common that they are pre-treated with enzymes, softening some of the harder degradable substances.
  • the pre-treated biomasses of R E nescience bioliquid from enzymated MSW and the Thin stilage form enzymated lignocellulosic biomass are both examples of biomasses that is expected to have some content of easily degradable organics that will make them good substances for the gas conversion time in a low H RT immibilised biofilm digester.
  • pig manure are normally thought of as a heavy degradable substance altogether as it both does not contain many easily degradables and as only app. 50% of the C OD content is convertible to biogas. C onsequently, it can be expected that the FAD digester will be challenged by being fed with pig manure.
  • the pig manure having the characteristics shown in Table 5 fed to the FAD digester performed very well, and gave the same yield as the manure would otherwise be expected to in the Maabjerg Bioenergy biogas plant from where the pig manure was sampled in the plant's feed tank.
  • the pig manure represents a challenge to the FAD biofilm in the sense, that the biofilm microbes have been raised with the selective pressure on the fermentative and acetoclastic bacteria because the hydrolysing and acetogenic steps were already performed by the enzymatic processes preseeding the formation of the R E nescience bioliquid and lignocellulosic Thin stillage.
  • the hydrolysing and acetogene bacteria are still presentand active and can shift rapidly between substances. No other biogas process is known that can shift so radically and fast between so different substrates.
  • Example "shock test” During this experiment, the feed in has been stopped for 1 5 days and the gas production of the 240 liter reactor was down to zero. In the lapse time of 2 days, a reactor was fed from 0 to nearly 70 liters per day, with a substrate of
  • This example shows the possibility of the system to produce biogas at high rates when being fed at a single and in multiple points.
  • This feature can help to distribute the high organic loads between the compartments of the reactor.
  • the reactor was fed in the two modalities.
  • all the organic load entered through the first compartment.
  • the substrate flow inside the reactor was distributed between the first and the third compartment. It has been proven to have high biogas production in both modalities.
  • the substrate can be fed into any of the recirculation streams of the reactor. This could be useful, if one of the pumps fails, so the reactors operation is able to proceed. This provide flexibility to the system as well as optimizing yield of production.
  • the invention relates to as disclosed herein to post- treatment of digestate e.g. to achieve higher yields of organic acid.
  • FIG. 23A illustrating schematically an embodiment of a system according to invention.
  • the system comprising a reactor tank with a stirrer inside the reactor. S ubstances, in this connection digestate, is taken out at the bottom of the reactor tank and processed in a processing device and re-introduced into the reactor tank after processing.
  • One or more non-disclosed FADs may be/are arranged inside the reactor.
  • the FADs may be in the form of inserts as disclosed herein.
  • This aspect of the invention resided inter alia in that in the atmospheric pressure conditions, only a limited part of the biomass can be converted to organic acids.
  • a post- treatment of digestate at higher temperatures will make the cellulose in the lignocellulosic structure available for enzymes.
  • the temperature of pretreatment will be 120-220C preferably in the area 1 50-200C .
  • Lower temperature treatment can limit inhibitor concentration that can cause problem.
  • the processing unit outlined schematically in fig. 23A is configured to at least increase the temperature of the substances located in the processing unit to between 120-220C, preferably in the range or 1 50-200C .
  • the pressure of the substances in the processing unit may advantageously be increase to above atmospheric pressure.
  • the result of the processing treatment is typically a higher concentration of bioconvertable material and less digestate to be incinerated. A higher
  • F ig.s 23B-E illustrate further configuration of post treatment of digestate according to preferred embodiments of the present invention.
  • digestate is extracted from a C ST R and post treated before at least a fraction of the post treated material is recirculated back to the C ST R .
  • fig.23C a digestate is extracted from a FAD and post treated before at least a fraction of the post treated material is recirculated to the FAD.
  • a digestate is extracted from a FAD and post treated before at least a fraction of post treated material is fed into a CSTR.
  • a digestate is extracted from a CSTR and post treated before at least a fraction of the post treated material is fed into a FAD.
  • the test configuration comprises a 10 L CSTR (see fig.24c) and a "2L FAD" 20% a 10 L FAD in operation (See fig.24b) both in automatic operation.
  • the test configuration is illustrated in fig.24a and the feed rates indicated in the figure are examples, and it may be assumed that what goes into the FAD goes into the CSTR except from the gas produced; further data as to feed rates is shown below in table 7. It is noted that the FAD used has been used with preferred flow path, and a forcing of the fluid to go up and down as disclosed e.g. in connetion with fig.s 1-4 can be applied and similar result as presented herein may be obtained.
  • TS Total Solids
  • VS Volatile Solids
  • ashes were analysed following NREL guidelines.
  • VFAs were quantified with Hach LCK365 Organic Acid cuvette test and DR spectrophotometer (Hach, Germany). Continuous gas measurement were monitored through the Bioreactor Simulator (BRS), Bioprocess Control, Sweden. Gas Composition was determined via gas chromatography, (model GC82 Mikrolab Aarhus A/S, Denmark).
  • the CSTR test digester is a 10L lab scale cylindrical tank with top-hinged agitation.
  • the FAD test digester (see fig. 24b) is a 2L lab scale cylindrical tank (as disclosed above) with vertically oriented immobilizing carriers and vertical circulating liquid flow through the immobilizing carriers.
  • the FAD digester content is continuously circulated through the immobilization carriers by means of a peristaltic pump.
  • the FAD digester is equipped with at top hinged agitation with propellers over and under the immobilization carriers.
  • the FAD digester liquid level is fixed by an inner overflow pipe FAD immobilization dimensions:
  • Immobilisation carrier type Bio-Blok 300 (commercially available)
  • the Bio-Blok 300 can be obtained e.g. from htip:/A t/w,expo- netd S tandard/P rodukter/Akvakultur/Generel%20information%20om%20BiO
  • Both the FAD and C ST R digesters were started on background of already operating AD systems (anaerobic digestion systems).
  • the two different digesters were filled with the same live inoculum from an AD process operating on similar substrates. In this manner, time from test start to fully operational systems were minimised and the risk of faulty results uncertainty due to different inoculi was believed to be eliminated.
  • the substrate used during the test was pre-hydrolysed OF MSW (organic fraction municipal solid waste).
  • the quality was 51 gVS/L (grams volatile solids per litre) substrate.
  • the pre-hydrolysation was obtained by a process comprising enzymatic degradation of carbohydrate polymers, for example cellulosic fibres to monomeric sugars that are then converted to biodegradable lactic acid by lactic acid bacteria taking the substrate pH below 5.
  • the expected gas production from the substrate is 0.5 L biogas per gram VS (Volatile S olids) with 60% C H4 in the biogas.
  • the C ST R digester maintains stable gas production at stable digester conditions or until the test time expires.
  • the H RT had been less than 10 days and reached a minimum H RT of 4.3 days during the last two days.
  • the productivity has shown a near-linear increase resulting in more than 2.5 times the gas flow compared to the level at 20 day retention time (see F igure 26).
  • the methane content in the biogas at the end of the period was 60 %.
  • VFA volatile fatty acid intermediates
  • productivity was 5.13 L biogas/(L digester x 24 h) corresponding to more than 3.1 L C H4/(L digester x 24 h). For a mesophilic CST R this is a high productivity and is believed to exceed high-performing thermophilic CSTR's.
  • FIG. 31 schematically illustrates three cross sectional views of preferred embodiments of an FAD tubular structure according to the present invention.
  • the tubular structure A1 is illustrated as a square, although it may have other shapes such as e.g. circular, thereby e.g. being a cylindrically shaped structure.
  • the biofilm carrier(s) A4 is illustrated as having a circular cross section and the dotted lines indicates that the biofilm carriers may be fluid penetrable.
  • the biofilm carriers A4 may be provided with other cross sections than circular.
  • F urther biofilm carriers A4 are preferably also considered to be tubular elements, and e.g. in case of having a circular cross section, the biofilm carriers A4 may form a cylindrical element, preferably open at both ends.
  • fig. 31 the dimensions shown are normalized with the side length of the tular structure A1 , this is indicated by the length of the sides of the tubular structure is 1 .
  • one biofilm carrier A4 is shown arranged inside the tubular structure A 1 ; it is noted that although the radius of the biofilm carrier A4 is shown to be 0.5, the actual radius could be slightly smaller to allow the biofilm carrier to be accommodated inside the tubular structure A1 (similarly applies for the two other figures of fig. 31 ).
  • biofilm carriers A4 are shown arranged inside the tubular structure A1 and in the lower part of fig. 32, sixteen biofilms carriers A are show arranged inside the tubular structure A1 .
  • digestate can be separated by separation means into
  • the digestate or dewatered digestate can be subjected to a processing step and be fed back into a fermenter (AD, FAD, C ST R, C ST R included a FAD), or even back to a enzymatical and/or microbial process producing a "bioliquid” (e.g. the substrate for biogas production via AD) such as a waste treatment facility, such as a MSW (municipal solid waste) treatment facility (e.g. a R E nescience process) essentially without significant heat/pressure treatment resulting in for example raw potatoes or other vegetables not always being converted efficiently to "bioliquid”.
  • a waste treatment facility such as a MSW (municipal solid waste) treatment facility (e.g. a R E nescience process) essentially without significant heat/pressure treatment resulting in for example raw potatoes or other vegetables not always being converted efficiently to "bioliquid”.
  • MSW military solid waste
  • a method of anaerobic digestion to biomethane comprising the steps of
  • a substrate feedstock having C OD content at least 30.0 g/L into a fixed film, fixed orientation, fixed bed bioreactor system in which the immobilization matrix is characterized by comprising a plurality of vertically oriented, porous tubular carriers supporting biofilm, and in which mixing zones are provided both above the upper openings and below the lower openings of the tubular carriers, and conducting anaerobic digestion of the feedstock with a hydraulic retention time of 120 hours or less while maintaining a flow velocity of at least 0.0002 m/s and a gas production rate of at least 5.0 liters/liter digester volume/day in such manner as to maintain a substantially laminar flow through the tubular carriers as well as mixing within each of said mixing zones.
  • the immobilization matrix is characterized by comprising a plurality of vertically oriented, porous tubular carriers supporting biofilm, and in which mixing zones are provided both above the upper openings and below the lower openings of the tubular carriers, and conducting anaerobic digestion of the feedstock with a hydraulic retention time
  • An anaerobic digestion bioreactor comprising a cylindrical tank having a plurality of internal, vertical biofilm carrier compartments defined by baffles or walls made from corrosion resistant and liquid impermeable material that are open at the top, where in each carrier compartment comprises a first shortened wall or underflow aperture on one side at the bottom which serves as an opening into another carrier compartment whereby fluid flows can be directed through succeeding compartments, and wherein a plurality of the carrier compartments further comprise a second shortened wall or overflow aperture at the top on a side other than that side which contains said first shortened wall or underflow aperture on one side at the bottom which serves as an opening into another carrier compartment whereby fluid flows can be directed through succeeding
  • compartments optionally further comprising a rotable scraper that is adapted to define sealed sections in a sedimentation zone situated beneath the lowest edge of the carrier compartments when in a closed position or to permit removal of sedimented solids when in an open position.
  • An insert for converting a continuously stirred tank reactor (C ST R) into a fixed film, fixed orientation, fixed bed anaerobic digestion reactor comprising - - interconnected baffles made from corrosion resistant and liquid impermeable material that define a plurality of vertical biofilm carrier compartments that are open at the top, each of which has a shortened wall or underflow aperture on one side at the bottom which serves as an opening into another carrier compartment whereby fluid flows can be directed through succeeding compartments, and most of which have a shortened wall or overflow aperture at the top on a side other than that which contains a shortened wall or underflow aperture at the bottom which serves as an opening into another carrier compartment whereby fluid flows can be directed through succeeding compartments.
  • a method of converting a C ST R tank into a fixed film, fixed orientation, fixed bed anaerobic digestion reactor comprising the steps of-
  • An insert comprising one or more baffles (1 ) defining at least two open compartments (2,3), said one or more baffles comprising one or more open edges (21 ), thereby when inserted into a tank reactor and when said tank reactor is in operation said one or more open edges define an underflow (22) or an overflow aperture thus forcing a fluid to flow upwardly or downwardly across said underflow or said overflow aperture.
  • said at least two compartments (6,7) further comprise a continuous closed side wall (4) surrounding said one or more baffles (5), wherein said one or more open edges (23) are displaced in respect to a height (24) of said continuous closed side wall.
  • biofilm carriers suitable for biofilm growth upon exposure to a flow of fluid containing biofilm precursors, said biofilm carrier comprising a three dimensional structure having at least one surface comprising cavities and protrusions thereby providing a rough surface.
  • said rough surface has a rough surface area Ra between 3 and 6 mm.
  • a bioreactor comprising
  • a container having one or more side walls and a bottom wall having an internal surface and a bottom opening;
  • a bioreactor according to item 22 comprising said insert according to any of the items 1 -21 , wherein said at least two removable open compartments are said at least two open compartments defined by said one or more baffles of said insert and wherein said at least one overflow aperture or underflow aperture are said underflow aperture or said overflow aperture defined by said one or more open edges.
  • a bioreactor according to item 25, wherein said means for forcing a fluid to flow are said biofilm carriers according to any of the items 12-21 .
  • 27. A bioreactor according to any of the items 22-26, further comprising means for promoting removal of precipitate deposited or located on said internal surface of said bottom wall of said container.
  • a bioreactor according to item 27, wherein said means for promoting removal of precipitate are one or more rotating means, such as one or more rotating scrapers.
  • a bioreactor according to item 28 wherein each of said one or more rotating scrapers has a scraping edge and a top edge opposite to said scraping edge.
  • 30 A bioreactor according to item 29, wherein, when not in motion, said one or more rotating scrapers lay in a positon that reduces or avoids short circuiting flow between neighbouring sections.
  • a bioreactor according to any of the items 29-31 comprising a gap between
  • a bioreactor according to item 37, wherein said means for promoting removal 5 of precipitate are adapted to define, when not in operation, static zones within said bottom chamber wherein cross-flow between compartments and said static zones is lower than a desired value, while when in operation, said static zones becomes mixing zones wherein cross-flow between compartments and said static zones is higher than said desired value.
  • width/size/diameter of said insert is substantially equal to or size substantially smaller than a width/size/diameter of said container.
  • level/part of said insert is located at a desired distance from said internal surface of said bottom wall.
  • a bioreactor according to item 41 wherein said means for keeping said insert at said desired distance are a plurality of protrusions located on said one or more
  • a bioreactor according to item 41 wherein said means for keeping sa id insert at said desired distance from said internal surface of said bottom wall are a curvature of said bottom wall, said curvature gradually reducing said
  • a bioreactor according to items 23-43 wherein when in operation, said open edges displaced in respect to each other define a plurality of underflow and overflow apertures whereby fluid flow from an underflow aperture of a first compartment upwardly towards an overflow aperture of a second subsequent compartment and downwardly towards an underflow aperture of a third
  • a bioreactor according to any of the items 47-50, wherein said means for recirculating a fluid are one or more recirculation pumps.
  • a bioreactor according to item 51 wherein said one or more recirculation pumps are at least in an amount equal to the amount of sections of said insert.
  • said one or more recirculation pumps are in an amount equal to the amount of compartments of said insert divided by two.
  • a method of operating a bioreactor said bioreactor according to any of the items 22-54, said method comprising:
  • a method according to item 58, wherein said forcing said fluid to flow further comprises forcing said fluid to flow through a preferential flow path defined by said plurality of biofilm carriers. 60. A method according to any of the items 58-59, wherein said forcing said fluid to flow, further comprises recirculating said fluid within each compartments.
  • At least one effluent tank (76) for collecting effluents from said one or more interconnected bioreactors.
  • C ST R C ontinuously Stirred tank Reactor
  • a method according to item 66, wherein said installing comprises fastening 30 said one or more baffles to one of more locations of said internal surface of said
  • any of the items 77-84 wherein the feedstock has a chemical oxygen demand (C OD) of at least 20.0 g/L, such as at least 30.0 g/L, at least 35 g/L, at least 40 g/L or at least 50 g/L or wherein the feedstock has a C OD of 20- 300 g/L, 30- 300g/L, 40-300g/L, 50-300g/L, 75-300 g/L, 100-300 g/L, such as 25-
  • C OD chemical oxygen demand
  • any of items 84-90 wherein the retention time is less than 1 10 hours, such as less than 1 00 hours, less than 90 hours, less than 80 hours, less5 than 75 hours, less than 60 hours, less than 50 hours, or less than 40 hours or wherein the retention time is 20-120 hours, 30-120 hours, 40-120 hours, 50-120 hours, 75-120 hours, 100-120 hours, or such as 50-1 10 hours, 50-100 hours, or 50-75 hours. 0 92.
  • any of items 84-91 wherein the flow velocity is at least 0.00025 m/s, such as at least 0.0005 m/s, at least 0.00075 m/s, at least 0.001 m/s, at least 0.0025 m/s, at least 0.005 m/s, or at least 0.0075 m/s or wherein the flow velocity is 0.0002-0.015 m/s, such as 0.0002-0.0125 m/s, 0.0002-0.01 m/s, 0.0002-0.0075 m/s, 0.0002- 0.005 m/s, or such as 0.00025-0.01 m/s, 0.0005-0.01 m/s, 0.00075- 0.01 m/s, 0.001 -0.01 m/s, 0.0025-0.01 m/s, 0.005-0.01 m/s, or 0.0075-0.01 m/s.
  • the gas production rate is at least 6.0 liters/liter digester volume/day, such as 7.0 liters/liter digester volume/day, at least 8.0 liters/liter digester volume/day, 9.0 liters/liter digester volume/day, at least 10.0 liters/liter digester volume/day, such as at least 12.5 liters/liter digester volume/day, at least 1 5 liters/liter digester volume/day or at least 20 liters/liter 1 0 digester volume/day wherein the gas production rate is 5.0-20 liters/liter digester volume/day, such as 6.0- 20 liters/liter digester volume/day, 7.0-20 liters/liter digester volume/day 8.0-20 liters/liter digester volume/day, 9.0 liters/liter digester volume/day, or 10-20 liters/liter digester volume/day.
  • the gas production rate is 5.0-20 liters/liter digester volume/day, such as 6.0- 20 liters/liter digester volume/
  • biomass is selected from the group consisting of waste, sewage, manure, or a cellulosic, hemicellulosic, lignocellulosic or starch containing biomass selected from wheat straw, corn stover, sugar cane
  • waste is selected from the group consisting of municipal solid waste (MSW), liquefied organic components of MSW, industrial waste, animal waste, plant waste or wastes from abattoirs, restaurants,
  • the feedstock is digested under anaerobic conditions to produce biomethane with a hydraulic retention time of 120 hours, or less, such as less than 1 10 hours, such as less than 1 00 hours, less than 90 hours, less than 80 hours, less than 75 hours, less than 60 hours, less than 50 hours, or less than 40 hours or wherein the retention time is 20-120 hours, 30-120 hours, 40-120 hours, 50-120 hours, 75-120 hours, 100-120 hours, or such as 50-1 10 hours, 50-100 hours, 50-75 hours, while maintaining a flow velocity of at least 0.0002 m/s through the bioreactor and/or a gas production rate of at least 5.0 liters/liter digester volume/day in such a manner as to maintain a substantial laminar flow through said biofilm carriers.
  • a hydraulic retention time 120 hours, or less, such as less than 1 10 hours, such as less than 1 00 hours, less than 90 hours, less than 80 hours, less than 75 hours, less than 60 hours, less than 50 hours,
  • An insert according to item 1 or 2 wherein the longitudinal extension of the tubular structure is straight or has having one or more straight sections or is curved, such as comprising one or more curved sections. 4. An insert according to any of the items 1 -3, comprising means for supporting said biofilm carrier s) located inside said tubular structure (A1 ).
  • biofilm carrier(s) is(are) suitable for biofilm growth upon exposure to a flow of fluid containing biofilm precursors, said biofilm carrier(s) comprising a three dimensional structure having at least one surface comprising cavities and protrusions thereby providing a rough surface.
  • a bioreactor system comprising one or more FADs (Fast Anaerobic
  • C ST Rs Continuous Stirred Tank R eactor(s)
  • the C ST Rs each comprising: - a tank reactor having one or more side walls and a bottom wall having an internal surface thereby defining a reactor volume and the tank reactor further comprising an inlet into and an outlet out from the reactor volume;
  • one of the openings of a FAD is in fluid communication with the reactor volume of a C ST R .
  • a bioreactor system according to any of the items 1 6-18, further comprising means for forcing, when in operation and the longitudinal extension of the tubular structure is vertical or substantial vertically orientated, a fluid to flow downwardly
  • each of said one or more rotating scrapers has a scraping edge and a top edge opposite to said scraping edge.
  • a bioreactor system according to any of the items 1 6-23, wherein said tank reactor comprises a bottom chamber defined/located between the internal surface of said bottom wall and a lowest level/part of said FAD(s).
  • a bioreactor system according to any of the items 1 6-26, wherein a lowest 25 level/part of the tubular structure of said FAD(s) is located at a desired distance from the internal surface of said bottom wall.
  • a bioreactor system according to item 28 wherein said means for keeping said FAD(s) at said desired distance are a plurality of protrusions located on said one or more side walls of said tank reactor and/or are a curvature of said bottom wall, said curvature gradually reducing said width/size/diameter of said tank reactor, said width/size/diameter defined by said one or more side walls of said tank reactor.
  • a bioreactor system according to any of the preceding items 1 6-30, wherein the total volume of the FAD(s) is at least 10%, such as at least 20 %, preferably at least 30%, such as at least 40%, preferably at least 50%, such as at least 60% of the total volume of the tank reactor.
  • a bioreactor system according to any of the preceding items 1 6-31 , wherein the ratio of volume FAD(s) to C ST R(s) is in the range of 0.01 to 0.05, such as in the range of 0.05-0.1 , preferably in the range of 0.1 -0.25, such as in the range of 0.25-0.5, preferably in the range of 0.5-0.75, such as in the range of 0.75-1 , preferably in the range of 1 -3, 2-5, or even in the range of 5-10.
  • a bioreactor system according to any of the preceding items 1 6-32, wherein the ratio of volume FAD(s) to C ST R(s) is less than 0.01 , such as less than or -0.025, preferably less than or ⁇ 0.05, such as less or ⁇ 0.1 , preferably less than or -0.2, such as less than or -0.3, preferably less than or -0.4, such as less than or -0.5, preferably less than or 0.6, such as less than or - 0.7, preferably less than or -0.8, such as less than or -0.9, preferably less than or -1 .0, such as less than or -1 .2, such as less than or -1 .4, preferably less than or -1 .6, such as less than or -1 .8, preferably less than or -2.0, such as less than or -2.5, preferably less than or -3.0, such as less than or -3.5, preferably less than or -4.0, such as less than or -5.0, preferably less than
  • a bioreactor system according to any of the preceding items 1 6-33 or an insert according to any of the preceding items 1 -1 5 , wherein the ratio between the circumference a cross section of the tubular structure (A1 ) and/or of the FAD(s) and the circumference of a cross section one or more fluid penetrable biofim carriers (A4) is smaller than 0.9, such as smaller than 0.8, preferably smaller than 0.7, such as smaller than 0.6, preferably smaller than 0.5, such as smaller than 0.4, preferably smaller than 0.3, such as smaller than 0.2, preferably smaller than 0.1 .
  • a bioreactor system according to any of the preceding items 1 6-34, wherein the system comprising at least two FADs and an C ST R and comprising flow regulating means, such as valve, fluid guides and pumps, for regulating flow of fluid through each of the FADs independently of independently of each other, so as to provide e.g. a smoothing in one of the FADs and a polishing in another FAD.
  • flow regulating means such as valve, fluid guides and pumps
  • a bioreactor system according to any of the preceding items 1 6-35, wherein the system comprises one FAD and/or a C STR with a FAD and one or more
  • a bioreactor system for Biphase Fast Anearobic Digestion comprising
  • tank reactor having one or more side walls and a bottom wall having an internal surface thereby defining a reactor volume the tank reactor further comprising an inlet into and an outlet out from the reactor volume
  • a break-up device such as a down sizing device, being in fluid
  • the bioreactor system further comprising one or more FADs comprising - an outer tubular structure (A1 ) having a longitudinal extension (L), being made from a fluidic non-penetrable material and having an opening (A2, A3) at each end of the outer tubular structure so as define a flow passage inside the outer tubular structure extending between said openings, and 5 - one or more fluid penetrable biofilm carriers (A4) arranged inside said outer tubular structure (A1 );
  • one of the openings of a FAD is in fluid communication with the reactor volume.
  • a bioreactor system according to item 37, wherein the break-up device such as a down-sizing device comprises a cutting/shredding element for break-up solid material by a cutting/shredding action.
  • a bioreactor system according to item 37 or 38, wherein the break-up device 1 5 comprises a heating element for heating an interior volume the break-up device, preferably the heating element is adapted to an aqueous fluid present in the interior volume to a temperature of at least 100°C, such as at least 120°C , preferably at least 140°C, such as at least 1 60°C .
  • a bioreactor system according to any of the items 37-39, wherein the break-up device comprising a pressurization element for pressurizing an interior volume of the break-up device, preferably the pressurization element is adapted to
  • aqueous fluid pressurize an aqueous fluid to a pressure of least 1 .1 bar, such as at least 1 .2 bar, preferably at least 1 .4 bar, such as at least 1 .8 bar.
  • a bioreactor system according to any of the items 37-41 wherein the break-up 30 device comprising a feeding element for feeding enzymes into an interior volume of the break-up device.
  • the break-up device comprising a catalytic element for catalytic reduction of biological material.
  • a system for processing sludge, such as digestate comprising:
  • a processing device configured for receiving the extracted sludge
  • a feeding device for feeding at least a fraction of the processed sludge into said biological treatment device and/or another biological treatment device.
  • the biological treatment device is a bioreactor system according to any of items 1 6-44.
  • processing device is a break-up device as defined in any of items 37-43.
  • the processing device comprises a heating element for heating an interior volume the break-up device, preferably the heating element is adapted to an aqueous fluid present in the interior volume to a temperature of at least 100°C, such as at least 120°C , preferably at least 140°C, such as at least 160°C .
  • the processing device comprising a pressurization element for pressurizing an interior volume of the break-up device, preferably the pressurization element is adapted to pressurize an aqueous fluid to a pressure of least 1 .1 bar, such as at least 1 .2 bar, preferably at least 1 .4 bar, such as at least 1 .8 bar.
  • one of the openings of a FAD is in fluid communication with the biological 5 treatment device.
  • a system according to items 56 or 57, biological treatment device is a
  • a) less 25 or larger than 500 such as between 25 and 500, preferably between 50 and 400, such as between 75 and 350, preferably 100
  • 1 0 c) 25 or more such as 50 or more, preferably 75 or more, such as 100 or more, preferably 1 50 or more, such as 200 or more, preferably 250 or more, such as 300 or more, preferably 350 or more, such as 400 or more, preferably 450 or more, such as 500 or more; and/or
  • a method of operating a bioreactor said bioreactor being a bioreactor system according to any of the items 1 6-36, a bioreactor system according to any of the items 37-44 44 or a system according to any of items 45-62, said method
  • a method according to item 66, wherein said forcing said fluid to flow further comprises forcing said fluid to flow through a preferential flow path defined by said plurality of biofilm carriers.
  • a method according to any of the items 63-71 further comprising:

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Wood Science & Technology (AREA)
  • Bioinformatics & Cheminformatics (AREA)
  • Zoology (AREA)
  • Microbiology (AREA)
  • Genetics & Genomics (AREA)
  • General Engineering & Computer Science (AREA)
  • Sustainable Development (AREA)
  • Biotechnology (AREA)
  • Biochemistry (AREA)
  • Biomedical Technology (AREA)
  • General Health & Medical Sciences (AREA)
  • Molecular Biology (AREA)
  • Immunology (AREA)
  • General Chemical & Material Sciences (AREA)
  • Clinical Laboratory Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Mechanical Engineering (AREA)
  • Apparatus Associated With Microorganisms And Enzymes (AREA)
  • Immobilizing And Processing Of Enzymes And Microorganisms (AREA)
  • Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)

Abstract

L'invention concerne de manière générale des procédés et des réacteurs pour la digestion et/ou une réaction microbiennes et spécifiquement des procédés et des réacteurs comprenant un insert comprenant un biofilm immobilisé sur une matrice de support. L'invention concerne également des procédés et des réacteurs pour la digestion anaérobie et spécifiquement des procédés et des réacteurs dans lesquels un biofilm de production du méthane est immobilisé sur une matrice de support ayant une orientation fixe.
PCT/DK2017/050110 2016-04-06 2017-04-06 Procédés et bioréacteurs pour la digestion microbienne employant des biofilms immobilisés WO2017174093A2 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DKPA201670203 2016-04-06
DKPA201670203 2016-04-06
EP16164279.8 2016-04-07
EP16164279 2016-04-07

Publications (3)

Publication Number Publication Date
WO2017174093A2 true WO2017174093A2 (fr) 2017-10-12
WO2017174093A3 WO2017174093A3 (fr) 2017-11-16
WO2017174093A9 WO2017174093A9 (fr) 2018-02-08

Family

ID=60001613

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK2017/050110 WO2017174093A2 (fr) 2016-04-06 2017-04-06 Procédés et bioréacteurs pour la digestion microbienne employant des biofilms immobilisés

Country Status (1)

Country Link
WO (1) WO2017174093A2 (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3524699A1 (fr) 2018-02-13 2019-08-14 Renescience A/S Matériaux de construction comprenant un digestat
WO2019201765A1 (fr) 2018-04-20 2019-10-24 Renescience A/S Procédé de détermination de composés chimiques dans des déchets
EP3569657A1 (fr) 2018-06-26 2019-11-20 Renescience A/S Composition de mélange d'asphalte comprenant un additif de digestat
WO2020072356A1 (fr) * 2018-10-01 2020-04-09 The Regents Of The University Of Michigan Insertion dans un bioréacteur et support de biofilm, appareil associé et procédés associés
WO2020250034A1 (fr) * 2019-06-11 2020-12-17 Metro Vancouver Regional District Enrichissement syntrophique pour un procédé de digestion amélioré
WO2022096406A1 (fr) 2020-11-04 2022-05-12 Renescience A/S Procédé de traitement enzymatique et/ou microbien de déchets comprenant la recirculation d'eau de traitement
WO2024068556A1 (fr) 2022-09-26 2024-04-04 Renescience A/S Procédé de traitement de fines
WO2024115642A1 (fr) 2022-12-01 2024-06-06 Renescience A/S Procédé de production d'hydrogène gazeux à partir de déchets

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4940540A (en) * 1987-07-08 1990-07-10 Tri-Bio, Inc. Submerged biological wastewater treatment system
US5451319A (en) * 1988-03-30 1995-09-19 Kobayashi; Yoshio Anaerobic digestion process for sewage sludge
JP3639007B2 (ja) * 1995-08-22 2005-04-13 京都水研株式会社 攪拌槽型のバイオリアクタ
US7297274B2 (en) * 2001-10-24 2007-11-20 University Of Florida Research Foundation, Inc. Fixed-film anaerobic digestion of flushed waste
DE102005047719A1 (de) * 2005-09-30 2007-04-12 Biogas Anlagen Leipzig Gmbh Verfahren zur Nutzung von Biomasse in einem Biogasprozess
DE102007024378B4 (de) * 2007-05-23 2009-06-04 Beck, Jürgen, Dr. Fermenter zur Erzeugung von Biogas aus pumpbarem organischen Material
US20110318778A1 (en) * 2010-06-29 2011-12-29 Petersen Gert Bjoern Organic Substrate Treatment System
GB2529804A (en) * 2014-08-19 2016-03-09 C Tech Innovation Ltd Method of pre-treating a feedstock for anaerobic digestion
EP3201308A1 (fr) * 2014-09-30 2017-08-09 Dong Energy Thermal Power A/S Procédés et bioréacteurs utilisés pour la digestion microbienne à l'aide de biofilms immobilisés

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3524699A1 (fr) 2018-02-13 2019-08-14 Renescience A/S Matériaux de construction comprenant un digestat
WO2019158477A1 (fr) 2018-02-13 2019-08-22 Renescience A/S Matériaux de construction comprenant un digestat
WO2019201765A1 (fr) 2018-04-20 2019-10-24 Renescience A/S Procédé de détermination de composés chimiques dans des déchets
EP3569657A1 (fr) 2018-06-26 2019-11-20 Renescience A/S Composition de mélange d'asphalte comprenant un additif de digestat
WO2020002153A1 (fr) 2018-06-26 2020-01-02 Renescience A/S Composition de mélange d'asphalte comprenant un additif de digestat
US11591559B2 (en) 2018-10-01 2023-02-28 The Regents Of The University Of Michigan Bioreactor insert and biofilm support, related apparatus and related methods
WO2020072356A1 (fr) * 2018-10-01 2020-04-09 The Regents Of The University Of Michigan Insertion dans un bioréacteur et support de biofilm, appareil associé et procédés associés
US11970684B2 (en) 2018-10-01 2024-04-30 The Regents Of The University Of Michigan Bioreactor insert and biofilm support, related apparatus and related methods
WO2020250034A1 (fr) * 2019-06-11 2020-12-17 Metro Vancouver Regional District Enrichissement syntrophique pour un procédé de digestion amélioré
US11274054B2 (en) 2019-06-11 2022-03-15 Metro Vancouver Regional District Syntrophic enrichment for enhanced digestion process
AU2020291810B2 (en) * 2019-06-11 2023-10-05 Greater Vancouver Sewerage & Drainage District Syntrophic enrichment for enhanced digestion process
WO2022096406A1 (fr) 2020-11-04 2022-05-12 Renescience A/S Procédé de traitement enzymatique et/ou microbien de déchets comprenant la recirculation d'eau de traitement
WO2024068556A1 (fr) 2022-09-26 2024-04-04 Renescience A/S Procédé de traitement de fines
WO2024115642A1 (fr) 2022-12-01 2024-06-06 Renescience A/S Procédé de production d'hydrogène gazeux à partir de déchets

Also Published As

Publication number Publication date
WO2017174093A9 (fr) 2018-02-08
WO2017174093A3 (fr) 2017-11-16

Similar Documents

Publication Publication Date Title
US20180237734A1 (en) Methods and bioreactors for microbial digestion using immobilized biofilms
WO2017174093A9 (fr) Procédés et bioréacteurs pour la digestion microbienne employant des biofilms immobilisés
Kariyama et al. Influence of mixing on anaerobic digestion efficiency in stirred tank digesters: A review
US7297274B2 (en) Fixed-film anaerobic digestion of flushed waste
AU2002348041B2 (en) Fixed-film anaerobic digestion of flushed manure
US10457613B2 (en) Anaerobic column reactor for biodegradation of wastes and the process thereof
US9567611B2 (en) Two-stage anaerobic digestion systems wherein one of the stages comprises a two-phase system
Demirer et al. Anaerobic digestion of dairy manure in a hybrid reactor with biogas recirculation
EP2558421B1 (fr) Système de traitement anaérobie des eaux usées
JP5114780B2 (ja) 嫌気性処理方法及び装置
Valijanian et al. Biogas production systems
AU2002348041A1 (en) Fixed-film anaerobic digestion of flushed manure
WO2010014919A1 (fr) Système et procédé de digestion anaérobie à plusieurs phases et en trois étapes
CN101981174A (zh) 生产生物气体的方法
WO2008026221A1 (fr) Digesteur anaérobie auto-mélangeant utile pour le traitement de déchets organiques solides
CN201087154Y (zh) 一种用于废水处理的倍增复合式厌氧水解反应器
ULLER Patent 2963026 Summary
Upadhyay et al. Characteristics, parameters, and process design of anaerobic digesters
JP7150899B6 (ja) 嫌気性処理装置及び嫌気性処理方法
WO2022123855A1 (fr) Dispositif de filtration
AU2008309672A1 (en) Flushed anaerobic digester with fixed biofilm
Anand et al. Challenges in Designing and Operation of a Bioreactor for Treatment of Wastewater
JP2002370099A (ja) メタン発酵処理装置
CN114804510A (zh) 一种猪场养殖废水厌氧膜生物处理工艺及***
Koppar Pseudo-Steady Model For Anaerobic Bio-Nest Reactor For Treatment Of Milk Parlor Wastewater

Legal Events

Date Code Title Description
DPE1 Request for preliminary examination filed after expiration of 19th month from priority date (pct application filed from 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17716455

Country of ref document: EP

Kind code of ref document: A2

122 Ep: pct application non-entry in european phase

Ref document number: 17716455

Country of ref document: EP

Kind code of ref document: A2