CA1117402A - Method and apparatus for processing waste - Google Patents

Abstract

METHOD AND APPARATUS FOR PROCESSING WASTE
Abstract of the Disclosure A method and apparatus for processing organic waste in an aqueous medium, which method comprises serially passing an organic waste-containing aqueous medium through a first immobilized aerobic microbe reactor and a second immobilized anaerobic microbe reactor. The apparatus comprises the two reactors which are serially connected. The disclosure also provides an apparatus for determining the biochemical oxygen demand of an organic waste in an aqueous medium.

Description

Back~round of the Invention This disclosure pertains to organic waste proc~3~ing.
More particularly, this disclosure pertalns to a method and appa~ratus for processing organic waste in an aqueous medium.
The disclosure also pertains to an apparatu~ for determining the biochemical oxygen demand (BOD) of an organic waste in an aqueous medium.
A variety of methods for the disposal of organic waste, either industrlal or agricultural, are available.
S~me of these methods, such as burial, land-fill, dumping at sea, and the like, have a negative environmental imp~ct and are not desirable. On the other hand, methods are available for converting org~nic waste to a source of energ~y and/or a ~ I ~
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usable product and include, among others, biological aerobic fermentation, biological anaerobic fermenta~ion, ther~ophilic aerobic digestion, destructive distillation (including hydrocarboniza~ion and pyrolysis), and incineration. W. J.
Jewell et al., "Methane Generation from Agricultural Wastes:
Review of Concept and Future Applications," Paper No. NA74-107, presented at the L974 Nor~heas~ ~egional Meeti~g of the American Society of Agricultural Engineers, West Virginia University, Morgantown, West Virginia, August 18-21, 1~74.
Of this latter group, biological anaerobic fermentation appears to be the most promising a~d has received consider-able attention in recent years.
Cl-rrent interest in biological anaerobic fermentation appears to be due, at Least in part, to the development of the anaerobic filter. See, for example, J. C. Young et al., Jour. Water Poll. Control Fed., 41, R160 (1969); P. L.
McCarty, "Anaerobic Processes", a paper presented at the Birmingham Short Course on Design Aspe~ts of Biological Treatment, International Association of Water Pollution Research, Birmingham, England, September 18, 1974; and J. C.
Jennett et al., Jour. Water Poll. Con_rol Fed., 47, 104 (1975). The anaerobic filter basically is a rock-filled bed similar to an aerobic trickling filter. In the anaerobic filter, however, ~he waste is distributed across the bott~m of the filter. The flow of waste is upward through the bed of rocks so that the bed is c~mpletely submerged. Anaerobic microorganism~ accumulate in the void spaces between the rocks and provide a large, active biological mass. The effluent typically is essentially free of biological solids.
See J. C. Young et al., supra at R160.

1~7~02 The anaerobic ~ilter, however, i5 bes~ suited for the trea~ment of water-soluble organic waste. J. C. Young et al., supra at R160 and R171. Furthermore, very long reten-~ion cimes of the waste in the filter are re~uired in order to achieve high reductions in the chemical oxygen demand (COD) of the waste to be treated. That is, depending upon the COD of the waste stream, reductions in such COD of fr~m 36.7 percent to 93.4 percent required reten~ion times of from 4.5 hours to 72 hours. J. C. Young et al., supra at R167. In addi~ion, such results were achieved with opti~ized synthetic wastes which were balanced in carbon, nitrogen, and phosphorus content and which had carefully adjusted pH
values .
Accordingly, there remains a great need for a waste processing method which can tolerate the presence of solids in the waste stream and which can more rapidly process the waste on an "as is" basis.

Summary of the Invention In accordance with the present invention, there is provided a method for processing organic waste in an aqueous medium which comprises serially passing an organic waste-containing aqueous medium through a first ~mmobilized micrabe reactor and a second immobili2ed mic~obe reactor, ln which:
A. the first reactos is an aerobic reactor containing a porous inorganic support which is suitable for the accumu-lation of a biomass, and B. the second reactor is an anaerobic r~actor c~m-prising a controlled-pore, hydrophobic inorganic membrane which contains a porous inorganic support which is suitable for the accumulation of a bi~mass.

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Also in accordance with the present invention, there is provided an apparatus for processing organic waste in an aqueous medium which c~mprises a first immobilized microbe react:or serially connected to a second immobilized microbe react:or, in which:
A. the first reactor is an aerobic reactor containing a porous inorganic support which is suitable for the accumu-Lation of a bi~mass, and B. the second reactor is an anaerobic reactor com-0 prising a controlled-pore, hydrophobic inorganic membrane which contains a porous inorganic support which is suitable for the accumulation of a biomass.
The present in~ention also pro~ides an apparatus for the determination of the bioch~mical ox~gen demand of an organic waste in an aqueous medium which comprises a sampling and/or sensing means serially con.nected to an immobilized microbe reactor which in turn is serially connected to a sampling and/or sensing mea~s, in which the reactor is an aerobic reactor containing a porous inorganic support which i5 suitable for the accumulation of a biomass.
The present in~ention further provides an apparatus for the determination of the biochemical oxygen demand of a~
organic waste in an aqueous medium which comprises a sampling and/or sensing means serially connected to a first immobilized microbe reactor which is serially connected to a second immobilized mic~obe reactor which is serially connected to a sampling and/or sensing means, in which:
A. the first reactor is an aerobic reactor containing a porous inorganic support which is suitable for the acc~lmu-lation of a bi~mass, and Div. I

74~.

B. the second reactor is an anaerobic reactor comprising a controlled-pore, hydrophobic inorganic membrane which contains a porous inorganic support which is suitable for accumulation of a biomass.
In the subject matter of this divisional application the present invention provides an apparatus for the determina-tion of the biochemical oxygen demand of an organic waste in an aqueous medium which comprises a sampling and/or sensing means serially connected to an immobilized microbe reactor which in turn is serially connected to a sampling and/or sensing means, in which the reactor is an aerobic reactor containing a porous inorganic support which is suitable for the accumulation of a biomass.
Brief Description of the Drawing The drawing illustrates one embodiment of the present invention as described by Examples 1 and 2, which embodiment comprises trea ing sewage to give an effluent having a significantly reduced oxygen demand and methane as a gaseous product.
Detailed Description of the Invention As used herein, the term "biodegradable" means only that at least some of the organic waste to be treated must be capable of being degraded by microorganisms. As a practical matter, at least about 50 percent by weight of the organic waste usually will be biodegradable. It may be necessary or desirable, however, to utilize in the process of the present invention waste having substantially lower levels of biodegrad-able organic matter.
Thus, the organic waste or the aqueous medium containing such waste can contain non-biodegradable organic Div .

~17402 matter and inorganic materials t provided that the organic waste and aqueous medium are essentially free of compounds having significant toxicity toward the microbes present in either reactor.
In general, the nature of the aqueous medium is not critical. In most instances, water will constitute at least about 50 percent by weight of the medium. Preferably, water - 5(a) -~ 4~ 2 will constitute from about 80 to about 98 percent by weight of the aqueous medium.
Frequently, the waste stream to be treated bY the process of the present invention can be used without any pretreatment. Occasionally, it may be desirable or neces-sary to dilute the waste stream with water, to separate from the waste stream excessive amounts of solids or excessi~ely coarse solids which might interfer with the pumping equipment necessary to move ~he aqueous medium through the processing apparatus of the present invention, or to lncrease the p~ of the aqueous medium by, for example, the addition of an inorganic or or~anic base, such as potassium carbonate, sodium hydro~ide, triethylamine, or the like. Alternatively, solid or essentially nona~ueous organic waste can be diluted with water as desired~
As already indicated, both the first and second reactor of the method and processing apparatus of the present invention contain a porous inorganic support which is suitable for the accumulation of a biomass. In the case of the second reactor, the inorganic support is contained within a controlled-pore, hydrophobic inorganic membrane.
As a matter of convenience, the inorganic support in the two reactors will be of the same type, although such is not required. Preferably, the inorganic support in each reac~ar is a porous, high surface æ ea inorganic support which is suitable for the accumulation of a high biomass surfacP within a relatively small volume. ~ore preferably, at least 70 percent of the pores of the inorganic support have diameters at least as large as the smallest major dimension, but less than about five times the largest major dimension, of the microbes present in the reactor. Most VZ

preerably, the average diameter of the pores of the inorganic support ~s in the range of from about 0.8 to about 220~.
As used herein, the expression "high surface area inorganic support" means an inorganic support hat~ing a surface area greater than about 0.01 m2 per gr~m of support.
In general, surface area is determined by inert gas adsorption or the B.E.~. method; see, e.g., S.J. Gregg and K.S.W. Sing, "Adsorption, Surface Area, and Porosity", Academic Press~
Inc., New Yor~, 1967. Pore diameters, on the other hand, are most readily determined by mercury intrusion porosimetry;
see, e.g., N.~. Winslow and J.J. Shapiro, "An Instrument for the ~easurement of Pore-Size Distribution by Mercury Penetra-tion", ASTM Bulletin ~. 236, Feb. 1959.
The inorganic support in general can be either siliceous or nonsiliceou~ metal oxides and can be either amorphous or crystalline. Examples of siliceous materials include, among others, glass, silica, cordierite, wollastonite, bentonite, and the like. ~xamples of nonsiliceous metal oxides include, among others, alumina, spinel, apatite, nicke~ oxide, titania, and the like. The inorganic support also ca~ be c~mposed of a mi~ture of siliceous and nonsiliceous materials, such as alumina-cordierite. Cordierite materials such as the one employed in the examples are preferred.
For a more complete description of the inorganic support, se~ commonly-assigned u.s. Patent No. 4,153,51~, filed Septembe~ 14, 1377, in the names of 2alph A. Messing and Robert A. Oppermann.
As already indicated, the inorganic support in each reactor prot-ides a locus for the accumulation o~ microbes.
The porous nature of the support not only permits the accumulation of a relatively high biomass per unit volume of reactor but also aids in the retention of the biomass within each reactor.
As used herein, the term "microbe" (and derivations thereof) is meant to include any microorganism which degrades organic materials, e.g., utilizes organic materials as nutrients. This terminology, then, also includes micro-organisms which utilize as nutrients one or more metabolites of one or more other microorgani~ms. Thu~, the term "micsobe", by way of illustration only, includes algae, bacteria, L0 molds, and yeasts. The preerred microbes are bacteria, molds, and yeasts, with bacteria being most preferred.
rn gene~al, the nature of the microbes present in each reactor is not critical. It i5 only necessary that the biomass in each reactor be selected to achieve the desired results. Thus, such biomass can consist of a single microbe species or several species, which species can be known or unknown (unidentified). Furthermore, the bi~mass in each reactor need not be strictly aerobic or strictly anaerobic, provided that the primary functions of the two reactors are consistent wQth their designations ~s aerobic and anaerobic reactors, respectively. The term "primary function" as used herein means that at least 50 percent of the biomass in each reactor functions in accordance with the reactor designation.
Stated differently, the demarcation line or zone between an aerobic function and an anaerobic function is not critical and need not always lie between the two reactors.
In practice, such demarcation line or zone can vary from the midpoi~t of the first reactor to the midpoint of the second reactor and to some extent can be controlled ~y regulating the ~mount of oxygen dissolved in the waste stream.

~ 2 Examples of microbes which can be employed in the aerobic reactor include, among others, strict aerobic bacteria such as Pseudomonas fluorescens, Acinetobacter calcoaceticus, and the like; facultative anaerobic bacteria such as Escherichia coli, Bacillus subtilis, Streptococcus faecalis, StaphYlococcus .
aureus, Salmonella typhimurium, Klebsiella pneumoniae, Enterobacter cloacae, Proteus vu~arls, and the like; molds such as Trichoderma viride, Aspirgillus ni~er, and the like;
and yeasts quch ac Saccharomyces cerevisiae, Sacchar~myces ellipsoideus, and the like.
Examples of microbes which can be utilized in the a~aerobic reactor include, among others, facultati~e anaerobic bacteria such as those listed above; anaerobic bacteria such as Clostridium butYricum, Bacteroides frazilis, Fusobacterium necrophorum, Leptotrichia buccalis, Veillonella parvula, Methanobacterium formicicum, Methanococcus mazei, Methanosarcina bar~eri, Peptococcus anaerobius, Sarcina ventriculi, and the like; and yeasts such as Sacchar~yces cerevisiae, Sacchar~mYces ellipsoideus, and the like.
~0 As already pointed out, the microbes employed in each reactor are selected on the basis of the results desired.
If a particular product is not re~uired, the choice of microbes can be made on the basis of waste conversion effi-ciency, operating parameters such as tem~erature, ~low rate, and the like, microbe availability, microbe stability, or the like. If, on the other hand1 a particular product is desired, the microbes typically are selected to maximize production of that product. By way of illustration only, the table beIow indicates some suitable c~mbinations of microbes which will yield the indicated prod~ct.

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In general, the microbes are introduced into each reactor in accordance with conventional procedures. For example, the reactor ean be seeded with the desired microbes, typically by circulating through the reactor an aqueous microbial suspension. Alterna~ively, the microbes can be added to the waste stream at any de~ired point. In cases where the was~e stre~m already contains the appropriate types of microbes, the pa~sage of such waste through the two reactors will in due course establish the requisite microbe colonies in each reactor.
The second reac~or also contains a controlled-pore, hydrophobic inorganic membrane. As used herein, the term "membrane" refers to a continuous, formed article, the shape and dimensions of which are adapted to process requirPments.
Thus, the membrane can be a flat or curved sheet, a three-~dimensional article such as a rectangular or cylindrical tube, or a c~mplex monolith ha~ing alternating channels for gas and aqueous medium. As a practical mat~er, the membrane most often will consist of a cylinder, open at both ends to provide passage of aqueous medium through its ~ength. Wall thickness is not critical, but must be sufficient to permit the membrane to withstand process conditions without defor-matio~ or breakage. In general, a wall thic~ness of at least about L.~ mm is desi~ed.
The membrane can be either siliceous or nonsiliceous metal oxides. Examples of siliceous materials lnclude, among others, glass, silica, wollastonite, bentonite, and the like. Examples of nonsiliceous metal oxides include, among ot~ers, alumina, spinel, apatite, nickel oxide, titania, and the like. Siliceous materials are preferred, 1 11 7~2 with glass and silica being most preferred. Of the non-siliceous metal oxides, alumina ~s preferred.
The membrane must have a controlled porosity such that at least about 90 percent of the pores have diameters of fr~m about 100~ to about 10~000~. Preferably, the pore diameter range will be fr~m about 900~ to about 9, oao~, and st preferably from about 1,500A to about 6,000~.
Methods of preparing inorganic membranes having con-trolled porosity as described above are well known to those having ordtnary skill in the art and nead not be discussed in d~tail kexe. See, e.g., U.S. Patent ~s. 2,106,764, 3,485,687, 3,549,524, 3,678,144, 3,782,982, 3,827,893, 3,850,849, and 4,00~,144, British Patent Speci~ication No.
1,392,220, and Canadi~n Patent ~o. 952,289. In addition, various porous inorganic materials a~e commercial~y a~ail-ab~e which can be formed into shaped articles by known methods. Among suppliers of such porous inorganic materials are the foLlowing: Alcoa, Catalytic Chemical Co. Ltd., Coors, Corning Glass Works, Da~ison Chemical, Fuji Davison Co. Ltd., Harrisons & Crosfield (Pacific) Inc., Kaiser Chemicals, Mizusawa Kagaku Co. Ltd., Reynolds Me~àls Company (Chemicals Division), Rhodia, Inc. CChemical Di~ision), and Shokubai Kasei Co. Ltd.
As a second requirement, in addition to cont~olled porosity, the Lnorganic membrane must be hydrophobic. Since the inorganic materials of which the membrane usually is composed are not inherently hydrophobic, the property o hydrophobicity normally must be imparted to the membrane by treating it either before or after the membrane is shaped or formed. As a practical matter, such treatment will be a post-formation treatment. The nature of the treatment is *Trade Mark -13-ill74U~: -not critical, and esqentially any ~seatment can be employed which will render the membrane hydrophobic. The property of hydrophobicity, however, ~ust be imparted throughout the entire void volume of the mem~rane, and not just to the external surface asea~.
Hydrophobicity is most conveniently imparted.to the shaped or formed memb~ane by immersing the membrane in an organic so.lvent which contains di~so~ved therein a suitable hydsophobic reagent, remo~ing the membrane from the solvent, and allowing it to air. dry. Although the concentration of the reagent is not criticalJ an especiall~ usefu~ concen-tration range has been found to be fr~m about 3 to about 25 percent, weight per volume o~ soL~ent. A most con~enie~t concentration is 10 pescent. Essentially any ~olvent in which the hydrophobic reagent i~ soluble can be employed.
Examples o~ suitable ~olvents. include, among others, hexane, cyclohexane, diethyl ~ther, acetone, methyl ethyL ketone, benzene, toluene, the xylenes, nitrobenzene, chlorobenzene, bromobenzene, chloroform, car.~on tetrachloride, and the like. Examples of suitable hydrophobic reagents inclu~e, ~mong others, natural waxes such as spermaceti, beesw æ , Chinese wax, carnauba wax, and the like; synthetic wa~es such as cet~l palmitate, cesotic acid, myricyl palmita~e, ceryl cerotate, and the like; aliphatlc hydrocar~ons such as octade~ane, eicosane, doc~sane, tetracosane, hexacosane, octacosane, triaco~tane, pe~tatriacontane, and the like;
polycyclic aramatic hytrocar~ons such as naphthalene, anthracene, phenanthrene, ch~ysene, pyrene, and the li'~e;
polybasic acids such as Empol Dimer Acid and Empol Trimer Acid (Emery Industries, Inc.~; polyamide resins such as the Emerez Polyamide Resins (E~ery Industries, Inc.);

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water-insoluble polymeric isocyanates such as poly(methylene-phenylisocyanate) which is commercially available as PAPI
(Upjohn Company); alkylhalosilanes such as octadecyltrichloro-silane, di(dodecyl)difluorosilane, and the like; and sLmilar materials. ~he alkyhalosilanes are preferred, with octadecyl-trichlorosilane bei~g most preferred.
Fr~m the foregoing, it should be apparent to one having ordinary s~ill in the art tha~ essentially any hydro-phobic ~eage~t which ~ill adhere to the i~organic me~brane with a reasonable degree of permanence can be employed.
Such adhesence can be by purely physical means, such as van der Waals attraction, by chemical mea~s, such as ionic or covalent bonding, os by a combination o~ physical and chemical means.
It should be apparent to one having ordinary s~ill in the æ t that th~ configurations of the first and second reactors are not critical to either the method or the processing apparatus of the present invention. Thus, the present invention comprehends any confi~uration of each reactor which is not inconsistent with the instant disclosure.
Most oten, each reactor ~ill be a conventional cylindrical or tubular plug flow-typ~ reactor, such as are described in the exam~les. Accordingly, each reactor typically comprises a cylinder or tube open at both ends which contains the inorganic support. In th~ case of the first reactor, such cylinder is com~ased of any suitable material which is impervious to both gases and liquids. Suitable materials include, among others, glass, stainless steel, gl~ss-coated steel, polyCt~trafluoroethylene), and the 11ke. The first reactor optionally is jac~ted. In the case of the second reactor, such cylinder is the controlled-pore, hydrophobic *Trade Mark -15-~ 7~
Lnorganic membrane. The second reactor also is optionally jacketed, especially where it is either desirable or necessary to contai~, isolate, analyze, utilize, or othe~ise handle gaseous products evolved during the process of the present invention. The ~ackets, if present, can be constructed from any of the usual materials, such as those List~d for the fixst ~eactor.
In more general terms, each reactor normally will be sh~ped in such a manner a~ to provide one or more channeIq for the passage of a 1uid. Where multiple channels are provided, such channeIs can provide independent flow of the fluid through such channels or they can be serially connected.
The aqueous medium can flow through such channel~ or around such channeIs. Thus, the inorganic support can be contained in such cha~nels or located around ~uch channels. For example, given the cylindrical reactor already described, the inorganic support can be contained within the cyllnder or tube. Alternatively, the cylinder or tube can be jac~eted and the inorganic support can be located between the jacket and the cylin~er or tube. Hence, the aqueous medium can flow eithes through or around the cylinder or tube. In the latte~ case with the second reactor, gaseous products will be remo~ed fr~m within the cylindrlcal membrane. Further-more, such gases, irsespecti~e of wh~ther they pass from or into the cyli~drical membrane, ean be disso~ved in a liquld soLvent ha~ing a high affi~ity for the gases, i.e., in which the gases have a high deg~ee of solubility. SuitaDle solvents for many gases include silicones and fluorocarbons, among other~. The use of such a gas solvent usually is neither necessary nor desired and, thererore, is not preferred.

Since the method and p~ocessing appara~us of the present invention are well-suited for the production of usable gases, it is preferred that the second, anaerobic reactor is sealably enclosed within a jac~et having a gas removal means attached thereto.
Under normal clr.cumstances, both reactors are main-tai~ed at a~bient tempera~uxe. Ind~ed, the proce-~s of the prese~t invention most preferably i~ carried ou~ at ambient tempesature. While pro.cess tt~e~atures are critical only to the extent that the microbes present in each.reactor remain vi~bIe, as a pract~cal.matter the process o the present invention ~ill be c~rried out-at a t~mperature of from about 10C. to about 60C. In those instances;where an elevated temperature is. desired, such eI.evated temperature usually i5 appLied only to the first, aerobic reactor, in which case the preferred temperatl~re range is from about 30C. to about.35C.
One preferred embod~ment of the process of the present in~entio~ is illustrated by the. examples in which a principal product is methane which is passed ~hrough the controlled-pore, hydsophobic inorganic membrane of the second, anaerobic reactor. Alternat~vely, process conditions and microbe cho.ices can be made which will yield ethanol as a principal product ~n the liquid eff.l.uen~ ~merging frNm the second reactor.
The present invention also pr.o~ides an apparatus for the determination of the biochemical oxygen demand CBOD~ of a biodegradab~e organic was.te ln an a~ueous medium. Such appara~us can take either of two configurations or embodi-ments: Cl) a sampling and/or sensing means serially connectedto the first, aerobic reactor descsibed hereinbefore, which reactor in turn i serially connected to a sampling and/or sensing means; and (2) a sampling andlor sensing means seria:Lly connected to the first, aerobic reactor desrribed hereiIlbefore, which first reactar is sesially connected to ~he second, anaerobic reactor described hereinbefore, which second reactor is serially connected to a sampling and/or sensing mean3.
A~ used herein, the tesm."'sampling and/or sensiQg means" is meant to include a sampling means, a sensing-~0 means, and a sampling. and sensinæ means.
Accordingly, the szmpling and/or. sen~ing means can benothing more than a port, fitted with, for exampLe, a stopcoc~
or rub~er septum, to pr.ovide a mean3 for the manual withdrawal of. a ~amp.le from the was.te stream. Alternatively, such ~am~ling means. can be an automated.sampling device which automatically removes samp.les of a precis~ size at predeter-mined intervals and s.tores such samp.les for future handling or analysis.
Examples of suita~le sensing means include, ~mong others, disso~ed oxygen sensor, conductivity sensor, ammonium ion sensor, pH electrode, and.the like. Actually, any sensing means can be used which will detect measurable differences in the organic was.te-containing aqueous medium which are the result of the biochemical conversions taking place in t~e apparatus for de~_rmlning BOD.
As con~platcd by the pre.sent ~n~ention, a sampling and sensing means can be any combination of a sampling means and a sensing mea~-~. F~r example, an aut~mated sampling de~ice can be seriall~ connect~d to an auto~ated device for determining COD by a chr~m.ic acid oxidation procedure.

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Other variation~ and c~mbinations, howe~er, will be readily pparent to one having ordinary skill in the art.
Finally, the two sampling and/or sensing means need not be physically discrete or ~eparate. That is, with appropriate connecting and waste stream directing means, a single sampling a~d/or sensing means can be em~loyed in the BOD apparatus of the present in~ention, and such use i9 within the ~cope of the in~tant~ diqc~osure. ~hus, when using a singIe sampling a~d/or sensing means, the waste st~e~m or a portion thereof first is passed through the ~ampling and/or sensing means.
Th~ wast~ stream then en~Pss the aesobic reactor. Upo~
exiti~g the aerobic reactor (or the anaerobic reactor if bot~ reactors ase ~mployed2, the waste stream or a portion thereof is directed to the sam~ling and/or sensi~g mea~s by appropriate connecting and directing means which are well k~own to thQse havi~g ortinar~ ~kill in the art.
The present in~ention i8 further described, but not limited, by the following Pxlmples which illustrate the use of the m~thod and apparatus of the present in~ention in the

2~ treatment of sewage. Unless otherwise stated, all tempera-tures are in degreas Cel~ius.
The proces~ employed ~n Examples ~ and 2 is desc~ibed below, wit~ refesence to the drawing.
Scwage 1 i3 pum~ed fr~m container 2 by pum~ 3 to aerobic reactor 4 v~a rubbes tublng 5 sealably connected to the pump and the aerobic saactor. The aesobic reactor consists of inner glass tube 6 sealable enclosed within gl~9s j ac~et ? . The inner glass tube contains inorganic carrier 8 such as that describad in u.s. Patent No. 4,153,510, which is suitable for the acc~mulation of a biomass. Sewage leavi~g the aerobic reactor is transported to anaerobic reactor 9 via rubber tubing 10 sealably connected to both react:ors. The anaerobic reactor conslsts of inorganic membrane 11 and glass jacket 12 having exit port 13. The L~or~a~ic membrane is filled with additional inorganic carrier 8 and is sealably enclosed within the glass jacket.
Ru~ber tubing 14, qealably connected to the exit p~rt of the jac~et, leads to pump 15 wh~ch remo~es gas ~methane) from ~0 air space 16 enclosed by the jac~et. Such gas in turn is colle~te~ by any suita~le means ~uc~ as by t~e displac~ment of wates- in a~ inverted ve~sel Cnot shown~. Sewage effluent 17 then is transp~rted, ~ia rubber tubing 18 sealably con-nected to the anaerobic reactos, to recei~ing vessel 19.
The sewage ~yloyed in each o~ the examples was obtained fr~m the i~let pipe to the Corning, ~ew York, Municipal Sewage Waste Treatment Plant. The sewage was stored at 4-6C. Prior to use, the sewage was filtered through cheese-cloth and glass wool to remove coarse particulate mat~er.
Sewage was callected eithe~ weekl~ or biweekly.

Example 1 Pump 3 consisted of a Fluid Metering pum~, RPlG6CSC
(Fluid ~etexing, Inc., Oystes 3ay, N.Y.) t wh~ch was connected to ae~obic reactor 4 with a 14-inch length or rubber tubing.
A 20-inc~ length of rubber tubing was attached to the intake side of the pump and led fr~m a flask containing s~wage.
The aerobic reactor consisted of a Pharmacia K16/20 column (Pharmacia Fine Chemicals, Uppsala, Sweden) with wate~ jacket; the water jac~et was left vented to the atmosphese. The column was charged with 24 g. of cordierite (CGZ) carrier having a pore diameter distribution of 2-9u and an average pore diamete~ of 4.5y. The carrier was seeded with sewage microbes by flowing through the reactor sludge~ obtained previously r~m a municipal anaerobic digestor.
The inorganic membrane 11 of anaerobic reactor 9 was a silica m~brane, prepared in accordance with known procedures;
see, for example, U.S. Patent Nos. 3,678,144, 3,782,982, and

3,827,893. The memb~ane was approgimately 18 cm. long with cros3-sectional dimen~ions of 10.5 mm. ~.d. and 15.5 mm.
o.d. The average pore diæmeter of the membrane was 3500 with a pore diameter distributio~ of 2000-3600~. ~all porosity was 60 percent and pore volume was 0.89 cc/g. The membrane was rendered hydrophobic by placing it in 75 ml. of a ten percent solution of octadecyltrichlorosilane in acetone and allowing it to soak overnight. The membrane then was removed from the qolution, washed with 500 ml. of acetone, and alr-dried.
The membrane was mounted in a Pharmacia K16/20 water jacket by means of the standard rubber sealing ring and threaded locking ring and was charged with ten g. of the CGZ
carrier. Both react~rs together had a total ~oid or fluid volume of ab t 30 ml.
The two reactoss were cqupled with about four inches of rubber tubing. One of the portQ o~ the anaeroblc reactor ~ac~et was sealed by attaching a short piece of Tygon tubing thereto and closing the tubing b~ means of a clam~. The other port was attached to a Buchler Polystaltic Pump ~Buchler Instruments, Inc., Fort Lee, ~.3.) with a l~ngth of thic~-walled Tygon tubing. Gas e~olved and passed t~rough the membrane was c~llected by the displacement of water in a calibrated cylinder inverted in water-filled, large, shallow *Trade Mark -21-vessel. The rate of gas evolu~ion was obser~ed and the coLlected gaq was analyzed at least daily b~ ma~s spectroscopy.
In addition, the chemical oxygen demand ~COD) of ~he sewage used a~ feed and the effluent emesging from the anaerobic reactor we~e determined periodically b~ standard, well-known colorimetric dichromate o~idation procedure The process wa~ ru~.~or a period of about nine mon~h~.
Although data wese generated o~ a dai~r basis, except for COD analyses, wee~ly averages of the data are pre~ented in TablQ l; in the table, COD analyses are averaged where more than one analy i~ was obtained per wee~.

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o ExampLe 2 The procedure of Example 1 was repeated, except that the aerobic reactor was charged with 19 g. of CGZ carrier, the carrier in t~e aerobic reactor was not seeded, the inorga~ic membrane of the anaerobic reactor was an alumina membr~ne, and ~he anaerobic reactor was charged with 18.4 ~.
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The alumina membrane was prepared in accordance w~th well-k~own proce~ures. Briefly, 300 g. o~ SA alumina con-L0 taining th~ee percent by weight o~ carbowax was isostatic-ally pressed at 1:,~58 kg./cm 2 C25,000 psi) in a m~ld whfch consi~ted of a cylindrical mandre~ havi~g a diæmeter of 1.9 cm. and a c~linder with rubber sleeve having an inner diameter of 3.65 cm~ The resulting cylindrical tube had the following cross-sectionaL dimenqions: ~.d., 1.9 cm., and o.d., 2.62 cm. The tube was turned o~ ~ lathe to an o.d. of 2.4 cm.
The tube wa~ about 36 cm. in leng~h. The tube then was fired in a furnace as follows: The furnace ~as heated to 500a (fr~m ambient temperatu~e~ at 50 per hour and held at 500 for two hours. The tem~eratuse then was increased to 1550 at a first rate of 50 per hour to 950 and a second rate of L00 per hour to 1550, at which temperature the furnace was held for f~e hours. The furnace then was cooled at 100 per hour to 950, and at 50 per hour to ~mbient tem~erature. The resulting alumina controlled-pore m~mbrane had an i.d. of 1.43 cm., an o.d. of 1.75 cm., and a wall thic~ness of 2.0 mm. Pore di~meter distribution was fram 3500~ to 4500~, with an average pore dizmeter of 4000~.
Wall porosity was 46.8 percent and pore volume was 0.22 cc./g. The membrane was rendered hydrophobic by placing it lii7 4 0 ~
in 50 m~. of acetone containing ten percent octadecyltri-chlorosilane and allowing it to react overni$ht at ~mbient temperature. The membrane then was removed fr~m the acetone solution and washed four times with 50-ml. portions of acetone. The membrane was air-dried for four hours, and then was heated at 120 for L.5 hours.
~ he data obtained ro~ this e~ample are s = arized in Table Ir, agai~ a~ weekly a~esages.

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--2~--Example 3 The procedure of Example 1 was repeated with s~me changes in equipment. The aerobic reactor consisted of a Lab-Crest column, without jacket, 400 x 15 mm. The reactor was chaxged with 50 g. of CGZ oarrier. The anerobic reactor consisted of an oute~ jac~et 3L.l cm. in length and a fritted glass m~mbrane 30.5 cm. in le~gth and ~.6 cm. in di~meter.
The membrane, which was fused to the outer jac~et, consisted of three sections of fritted glass tubing of equal Length ~0 which h~d been fused together. The ~otal length of the a~aerobic reactor was 40.6 cm. The membrane had a pore di~meter distribution of 3-6~ and a~ a~erage pore diameter of 4.5~. The membrane was made hydrophobic by allowing it to react wi~h 130 ml. of ten percent octadecyltrichlorosilane in acetone at ~mbient temperatuxe for about three days. The membrane t~en was remo~ed from the acetone solution and washed successively with two 130-ml. portions of acetone, two 130-ml. portions of methanoL, and a L30-ml. portion of ac~tone. The membrane was air-dried by aspiration. The anaerobic reactor was charged with 23 g. of CGZ carrier.
The gas pump wa~ a Cole-Parmer Masterflex peristaltic pump.
T~e results are summarized ln Table III. The membrane, howe~e~, passed liquid water during the time the process was in operatio~, demonstrating that the pore diametess of the fritted glass membrane in gene~al we~e too large.

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1~1 7 ~(~2 Ex~mple 3 also illustrates a preferred embodiment of the process of the present invention, which embodiment com-prises establishing an additional microbe coLony on the gas-space side of the i~organic membrane of ~he anaerobic react:or. Most preferab~y, such microbes will be photo-synthetic microbes, examples of which include, among others Rhodospirillum rubrum, r~matium Sp., Chlorobium thlosulf-atophilum, Chloropseudomonas ethyLica, Chorella Sp., Scenedesmus Sp., Chl`~myd~monas Sp., Anki~trodesmus Sp., Chondrus S~., L0 Corallina Sp., Callilhamnion Sp., and the like.
Th~ examples which follow illustrate one embod~ment of the B~D apparatu~ of the present in~ention.

Example 4 A two-liter reagent bottle with a side arm at the bottom was con~ected, via a Length of Tygon tubing attached ta the 3ide arm, to the inlet port of a F~uid Metering, Inc.
ModeI ~P G-6 pum~ (Fluid Metering, Inc., Oyster Bay, New York). The outlet port of the pump was attached, again via Tygon tubing, to the bott~m of a vertically-mounted 9 ~ 150 mm. Fis~er and Porter chr~matographic column (obtained fr~m Arthur H. Thomas Co., Philadelphia, Pa.). The column was charged with 6.5 g. o~ the CGZ carries described in Example 1. The top of th~ column was connected b~ ~ygon tubing to the inlet part o~ a cell h~ing sealably mounted therein the dissalved oxygen sensor of a Di~fusion O~gen Analyzer (International Biophysics Corp., Irvine, Cal.). The outlet port of the cell was connected with Tygon tubing to a receiving vessel. Another dissolved oxygen sensor was placed in ~he reagent bottle which ser~ed as a waste stream reserv~ir. Each dissol~ed oxygen sensor was standardized *Trade Mark _33_ ~ ~7 4 0 2 against air-~aturated water at 21.9Z saturation.
The column was seeded by continuously recirculating a volume of sewage through the column a~ a flow rate of 1 ml. /min. for five days. A ~terile, standard BOD solution containing 15~ mg/liter each of glutæmic acid and glucose wa~ passed through the column at 0.37 ml./mi~ for 24 hours as. a preconditioning to insure adequat~ bioaccumulation prior t~ collecting oxygen uptake data~ he s~antard BOD
solution then was passed through the column or imm~bilized LO aerobic mlcrobe reactor. T~e efluent percant saturation was measured at. three~different flow rates. In each case, the.percent 3aturation of the feed in the reses~oir was 2L.9% and. the effluent pescent qaturation reading- stabilized withi~ 20-60 min. after changing the flow rate. The results are summarized in Table IV.

TABLE I~
Oxygen Uptake In An Aerobic Reactor BOD ApParatus Flow ~ate (ml./min.) Effluent ~ Saturation O.L9 7a 0.37 10 2.07 18.5 ~ecreased to 4.5 af.ter an additio~al 12 hours.

Fr~m Table IV, it. is apparent that oxygen uptake is in~ersely propo~tional.to the flow rate. O~ygen upta~e, expressed as the percentage of dissol~ed oxygen consumed, is summarized in Table V and was calculated in accordance with the following formul~:

1 ~1 74 0~2 % 2 consumed ~ Feed % Sat'n - Eff. /~ Sat'n Feed 70 Sat'n x 100 TABLE V
Percentage of Disso~ved Oxygen Consumed In An Aerobic ~eactor BOD Apparatus Flow Rate, ml./min. 7 -2 Consumed 0. 19 68a 0~37 54 2.07 16 LO aIncreased to 79% a~tex an addit~onal 12 hours.

Example 5 The procedure of Example 4 was repeated, e~cept that the column was seeded with 200 ml. of an overnight tryptic soy broth culture of Escherichia coli (109 cells/ml.) and th~ standasd BOD sclution was replaced with sterile broth.
Ater the 24-hour preconditioning period, the effluent per-cent saturation was measured and ~ound to be 0~; the broth percent saturation originally was 21.9%. Thus, 100% of the dissolved o~ygen was consumed.
Examples 4 and 5 clearly demonstrate the feasibility of measur~ng a difference in an organic waste-containing aqueous medium, which difference is the result of biochemical con-~essions (o~idations) taking place in the BOD apparatus aerobic reactar.
Such a measurable difference then is readily correlated to BOD by known procedures. For one example of such a correlation, see I. Karube et al., Biotechnol. ~ioeng., 19, 1535 (1977). Thus, for a given aerobic reactor (or aerobic reactor and a~aerobic reac~ar serially connected), passing standard solutions ha~ing varying concentrations of organic 1~7~C~Z
material at a given flow rate will yield a set of, for example, oxygen uptake data. The BOD values of such standard solutions can be determined by conventional methods to give a set of conventional BOD values. The ~wo sets of data then can be combi~ed in graph form to gi~e a standard curve ~or each flow rate employed. The BOD of any organic waste in an aqueous medium then is determined quic~ly and simply by passing such aqueous medium through the BOD apparatus and comparing the data obtained with the appropriate standard curv~.

Claims (7)

Div.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An apparatus for the determination of the biochemical oxygen demand of an organic waste in an aqueous medium which comprises a sampling and/or sensing means serially connected to an immobilized microbe reactor which in turn is serially connected to a sampling and/or sensing means, in which the reactor is an aerobic reactor containing a porous inorganic support which is suitable for the accumulation of a biomass.

2. The apparatus of Claim 1 in which two separate sampling and/or sensing means of the same type are employed.

3. The apparatus of Claim 2 in which each sampling and/or sensing means comprises a dissolved oxygen sensor.

4. The apparatus of Claim 2 in which each sampling and/or sensing means comprises an ammonium ion sensor.

5. The apparatus of Claim 1 in which a single sampling and/or sensing means is employed.

6. The apparatus of Claim 5 in which the sampling and/or sensing means comprises a dissolved oxygen sensor.

7. A method for the determination of the biochemical oxygen demand of an organic waste in an aqueous medium which comprises the steps of:
A. measuring the dissolved oxygen content of the organic waste-containing aqueous medium, B. passing without recirculation the organic waste-containing aqueous medium through an immobilized aerobic microbe bioreactor containing a porous, dimensionally stable inorganic support which is suitable for the accumulation of a biomass, C. measuring the dissolved oxygen content of the effluent from the bioreactor, D. determining the difference between the dissolved oxygen measurements of steps A and C, and, E. correlating the difference obtained in step D with biochemical oxygen demand by means of a standard curve obtained with samples having known biochemical oxygen demand values.