CA1117668A

CA1117668A - Method and apparatus for processing waste

Info

Publication number: CA1117668A
Application number: CA000318842A
Authority: CA
Inventors: Ralph A. Messing
Original assignee: Corning Glass Works
Current assignee: Corning Glass Works
Priority date: 1978-02-24
Filing date: 1978-12-29
Publication date: 1982-02-02
Also published as: JPS6218233B2; GB2078705B; GB2014979A; GB2014979B; FR2418204B1; GB2078705A; FR2418204A1; JPS54124557A; DE2905391A1; DE2905391C2

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 processing.
More particularly, this disclosure pertains to a method and apparatus for processing organic waste in an aqueous medium.
The disclosure also pertains to an apparatus for determining the biochemical o~ygen d~mand (BOD) of an organ~c waste in an aqueous ~edium.
A variety of methods for the dlsposal of organic waste, either industrial or agricultural, are available.
Same 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 organic waste to a source of energy a~d/or a ~2 ~ `' ~

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usable product and include, among others, biological aerobic fermentation, biological anaerobic fermentation, thermophilic aerobic digestion, destructive distillation (including hydrocarbonization 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 1974 Northeast Regional Meeting o, the American Society o~ Agricultu~al Engineers, West Virginia University, Morgantown, West Virginia, August 18-21, 1974.
Of this latte~r group, biological anaerobic fermentation appears to be the most promising and has received consider-able attention in recent yPars.
Current 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 P _ . Control Fed., 41, R160 (1969); P. L.
McCarty, "Anaerobic Processes", a paper presented at the Birmingham Short Course on Design Aspects of Biological Treatment, International Association of Water Pollution Research, Birmingham, England, September 18, 1974; and J. C.
Jennett et al., Jour. Water Poll. Control Fed., 47, 104 .
(1975). The anaerobic filter basically is a rock-filled bed similar to an aerobic trickling filter. In the anaerobic filter, howe~er, the waste is distributed across the bottom of the filter. The flow of waste is upward through the bed of rocks so that the bed is completely submerged. Anaerobic microorganisms accumulate in the void spaces between the rocks and provide a large, a~tive biological mass. The effluent typically is essentially free of biological solids.
See J. C. Young et al., supra at R160.

7~8 The anaerobic filter, howe~er, is best suited for the treatment of water-soluble organic waste. J. C. Young et al., supra at R160 and R171. Furthermore, very long reten-tion times of ~he waste in the filter are required 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 from 36.7 percent to 93.4 percent required retention times of from 4.5 hours to 72 hours. J. C. Young et al., supra at R167. In addition, such results were achieved with optimized 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.

Sum~ary 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 immobilized microbe reactor and a second immobilized microbe reactor, in which:
A. the first reactor is a~ 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 reactor com-prising a controlled-pore, hydrophobic inorganic membrane which contains a porous inorganic support which is suitable for the accumulation of a biomass.

Also in accordance with the present invention, there is provided an apparatus for processing organic waste in an aqueous medium which comprises a first immobilized microbe reactor serially connected to a second immobilized microbe reactor, in which:
A. the first reactor 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 reactor com-prising a controlled-pore, hydrophobic inorganic membrane which contains a porous inorganic support which is suitable for the accumulation of a biomass.
The present invention also provides 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.
The present invention fur~her provides an apparatus ~or the determination of the biochemical o~ygen demand of an 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 microbe 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 ~he accumu-lation of a biomass, and 1 1 ~7 ~6 ~

B. the se~ond reactor is an anaerobic reactor com-prising a controlled-pore, hydrophobic inorganic membrane which contains a porous inorganic support which is suitable for the accumulation of a biomass.

Brief Descri tion of the Drawin P _ _ g The drawing illustrates one embodiment of the present invention as described by Examples 1 and 2, which embodlment comprises treating sewage to give an effluent having a significantly reduced oxygen demand and methane as a gaseous product.

Detailed Descri tion 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 biodegradable organic matter.
Thus, the organic waste or the aqueous medium contain-ing such waste can contain non-biodegradable organic matter and inorganic materials, 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 msst instances, water will constitute at least about 50 percent by weight of the medium. Preferably, water 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 excessively coarse solids which might interfer with the pumping equipment necessary to mQVe the aqueous medium through the processing apparatus of the present invention, or to increase the pH of the aqueous medium by, for example, the addition of an inorganic or organic base, such as potassium carbonate, sodium hydroxide, triethyLamine, or the like. Alternatively, solid or essentially nonaqueous organic waste can be diluted with wate~ 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 reactor is a porou~, high surface area inorganic support which is suitable for the accumulation of a hi~h biomass surface within a relatively small volume. More 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 ~L~17668 preferably, t~e a~e~age di~meter ~ the pores of the inorganic support is in the range of from about 0.8 to about 220~.
As used herein, ~he expression "high surface area inorganic ~upport" means an i~organic support having a surface area greater than about 0.01 m2 per gram of support.
In general, surface area is determined by inert gas adsorption or the B.E.T. method; see, e.g., S.J. Gregg and K.S.W. Sing, "Adsorption, Surface Area, and Porosity", Academic Press, Inc., New York, 1967. Pore diameters, on the other hand, are most readily determined by mercury intrusion porosimetry;
see, e.g., N.M. Winslow and J.J. Shapiro, "An Instrument for -the Measurement o Pore-Size Distribution by Mercury Penetra-tion", ASTM Bulletin No. 236, Feb. 1959.
The inorganic support in general can be either siliceous or nonsiliceous metal oxides and can be either amorphous or crystalline. Examples of siliceous materials include, among others, glass, silica, cordierite, wollastonite, bentonite, and the like. Ex~mples of nonsiliceous metal oxides include, among others, alumina, spinel, apatite, nickel oxide, titania, and the like. The inorganic support also can be c~mposed of a mixture of siliceous and nonsiliceous materials, such as aLumina-cordierite. Cordierite materials such as the one employed in the examples are preferred.
For ~ more complete description of the inorganic support, see commonly-assigned u.S. Patent No. 4,153,51~, filed September 14, 1977, in the names of Ralph A. Messing and Robert A. Oppermann.
As already indicated, the inorganic support in each reactor provides a locus for the accumulation of microbes.
The porous nature of the support not only permits the accumulation of a relatively high biomass per unit volume of 11~6~

reactor but also aids in the reten~ion of ~he biomass within each reactor.
As used herein, the term "microbe" tand derivations thereof) is meant to include any microorganism which degrades organic materials, e.g., utilizes organic materials as nutrients. This te~minology, then, also includes micro-organi~ms which utilize as nutrients one or more metabolites of one or more other microorganisms. Thus, the term "microbe", by way of illustration only, includes al~ae, bacteria, molds, and yeasts. The preferred microbes are bacteria, molds, and yeasts, with bacteria being most preferred.
In general, the nature of the microbes present in each reactor is not critical. It is 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 biomass in each reactor need not be strictly aerobic or strictly anaerobic, provided that the primary functions of the two reactors are consistent with their designations as 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 diferently, 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 midpoint of the first reactor to the midpoint of the second reactor and to some extent can be controlled by regulating the amount of oxygen dissolved in the waste stream.

1~76~ !3 Examples of microbes which can be employed in the aerobic reactor include, among others, strict aerobic bacteria such as Pseudomonas fluorescens, ~cinetobacter calcoaceticus, and the like; facultati~e anaerobic bacteria such a~ ~scherichia coli, Bacillus subtilis, Streptococcus faecalis, Staphylococcus aureus, Salmonella typhimurium, Klebsiella pneumoniae, Enterobacter cloacae, Proteus w lgaris, and the like; molds such as Trichoderma viride, Aspir~illus ni~er, and the like;
and yeasts such as Saccharomyces cerevisiae, Saccharomyces ellipsoideus, and the like.
Examples of microbes which can be utilized in the anaerobic reactor include, among others, facultative anaerobic bacteria such as those listed above; anaerobic bacteria such as Clostridium butyricum, Bac~eroides frazilis, Fusobacte ium necrophorum, Leptotrichia buccalis, Veillonella par w la, Methanobacterium formicicum, Methanococcus mazei, Methano~arcina barkeri, Peptococcus anaerobius, Sarcina ventriculi, and the like; and yeasts such as Saccharomyces cerevisiae, Saccharomyces ellipsoideus, and the like.
As already pointed outJ the microbes employed in each reactor are selected on the basis of the results desired.
If a particular product is not required, the choice of microbes can be made on the basis of waste conversion effi-ciency, operating parameters ~uch as temperature, flow rate, and the like, microbe availability, microbe stability, or the like. If, on the other hand, a particular product is desired, the micro~es typically are selected to maximize production of that product. By way of îllustration only, the table below indicates some suitable ccmbinations of microbes which will yield the indicated product.

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~L11761~8 In general, the microbes are introduced into each reactor in accordance with conventional procedures. For example, the reactor can be seeded with the desired microbes, typically by circulating through the reactor an aqueous microbial suspension. Alternatively, the microbes can be added to the waste stream at any desired point. In cases where the waste stream already contains the appropriate types of microbes, the passage of such waste through the two reactors wilL in due course establish the requisite microbe colonies in each reactor.
The second reactor 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 requirements.
Thus, the membrane can be a flat or curved sheet, a three-dimensional article such as a rectangular or cylindrical tube, or a complex monolith having alternating channels for gas and aqueous medium. As a practical matter, the membrane most o~ten will consist of a cylinder, open at both ends to provide passage of aqueous medium through its length. Wall thickness is not criticaL, but must be sufficient to permit the membrane to withstand process condîtions without defor-mation or breakage. In general, a wall thickness of at least about 1.0 ~m is desi~ed.
The membrane can be either siliceous or nonsiliceous metal oxides. ExampLes of siliceous materials include, among others, glass, silica, wollastonite, bentonite, and the like. Examples of nonsiliceous metal oxides include, among others, alumina, spinel, apatite, nickel oxide, titania, and the like. Siliceous materials are preferred, ~L76t;~

with glass and silica being most preferred. Of the non-siliceous metal oxides, alumina is preferred.
The membrane must have a controlled porosity such that at least about 90 percent of the pores have diameters of from about 100~ to about 10,000~. Preferably, the pore di~meter range will be fr~m about 900~ to about 9,000~, and most 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 tho e having ordinary skill in the art and need not be discussed in detail here. See, e.g., U.S. Patent Nos. 2,106,764, 3,485,687, 3,549,524, 3,678,144, 3,782,982, 3,827,893, 3,850,849, and 4,001,144, British Patent Specification No.
1,392,220, and Canadian Patent No. 952,289. In addition, various porous inorganic ~aterials are commercially a~ail-able which can be formed into shaped articles by known methods. Among suppliers of such porous inorganic materials are the following: Alcoa, Catalytic Chemieal Co. Ltd., Coors, Corning Glass Works, Davison Chemical, Fuji Davison Co. Ltd., Harrisons & Crosfield (Paci~ic~ Inc., Kaiser Chemicals, Mizusawa Kagaku 5O. Ltd., Reynolds Metals Company (Chemicals Division), Rhodia, Inc. (Chemical Division), and Shokubai Kasei Co. Ltd.
As a second requirement, in addition to controlled porosity, the inorganic membrane must be hydrophobic. Since the inorganic materials of which the membrane usualLy is composed are not inherent~y h~drophobic, the property of hydrophobicity normally must be lmparted 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-~76f~8 not critical, and e~,sent~ally any ~reatment can be employed which will render the membrane hydrophobic. The psoperty of hydrophobicity, however, must be imparted throughout ~he entire void volume of the membrane, and not just to the external surface areas.
Hydrophobicity is most conveniently imparted to the shaped or formed membrane by ~mmerslng the membrane in an organic solvent which contai~s dis~olved therein a suitable hydrophobic reagent, removing the membrane from the solvent, and allowing it to air dry. Although the concentration of the reagent is not critical, an especially useful concen- !
tration range has been found to be fr~m about 3 to about 25 percent, weight per volume of solvent. A most convenient concentration is 10 percent. Essentially any solvent in which the hydrophobic reagent is soluble can be employed.
Examples of suitable solvents i~clude, ~mong others, hexane, cyclohexane, diethyl ether, acetone, methyl ethyl ketone, benzene, toluene, the xylenes, nitrobenzene, chlorobenzene, bromobenzene, chlorsform, carbon tetrachloride, and the like. Examples of suitable hydrophobic reagents include, among others, natural waxes such as spermace~i, beeswax, Chinese wax, carnauba wax, and the like; synthe~ic waxes such as cetyl palmitate, cerotic acid, myricyl palmitate, ceryl cerotate, and the like; ali~hatic hydrocarbons such as octadecane, eicosane, docosane, tetracosane, hexacosane, octacosane, triacontane, pentatriacontane, and the like;
polycyclic aromatic hydrocarbons such as naphthalene, anthxacene, phenanthrene, chrysene, pyrene, and the like;
polybasic acids such as Empol Dimer Acid and Empol Trimer Acid (Emery Industries, Inc.~; polyamide resins such as the Emerez Polyamide Resins (Emery Industries, Inc.);

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water-insoluble polymeric isocyanates such as poly(methylene-phenylisocyanate) which is commer ially available as PAPI
(Upiohn Company); alkylhalosilanes such as octadecyltrichloro-silane, di(dodecyl)difluorosilane, and the like; and similar materials. The alkyhalosilanes are preferred, with octadecyl-trichl~rosilane being mo~t preferred.
From the foregoing, it should be appa~ent tO o~e having ordinary skill in the a~t that essentially any hydro-phobic reagent which will adhere to the inorganic membrane with a reasonable degree o permanence can be employed.
Such adherenee can be by purely physical means, such as van der Waals attraction, by chemical means, such as ~onic or covalent bonding, or by a comblnation of physical and chemical means.
It should be apparent to one having ordinary skill in the art that the configurations of the first and second reactors are not cri~ieal to either ~he method or the processing apparatus of the present invention. Thus, the present inve~tion c~mprehends any confi~u~ation of each reactor which is not inconsistent with the instant disclosure.
Most often, each reactor will be a conventional cylindrical or tubular plug flow-type ~eactor, such as are described in the examples. Accordingly, each reactor typically c~prises a cylinder or t~be open at both ends which contains the inorganic support. In the case of the fir~t reactor, such cylinder is com~osed of any suitable material which is impervious to both gases and li~uids. Suitable materials include, among others, glass, stainle~s steel, gl~ss-coated steel, pol~(tetrafluoroethylene). and the like. The first reactor optionally is jacketed. In the case of the second reactor, such cylinder is the controlled-pore, ~ydrophobic *Trade Mark 1 ~ ~7 ~ ~

inorganic membrane. The second reactor also is optionally jacketed, especially where it is either desirable or necessary to contain, isolate, analyze, utilize, or otherwise handle gaseous products evolved during the process of the present invention. The jackets, if present, can be constructed from any of the usual materials, such as those listed for the first reactor.
In more general terms, each reactor normally will be shaped in such a manner as to provide one or more channels for the passage of a fluid. Where multiple channels are provided, such chann~ls can provide independent flow of the fluid through such channels or they can be serially connected.
The aqueous medium can flQw through such channels or around such channels. Thus, the inorganic support can be contained in such channels or located around such channels. For example, given the cylindrical reactor already described, the inorganic support can be contained within the cylinder or tube. Alternatively, the cylinder or tube can be iacketed and the inorganic support can be located between the jacket and the cylinder or tube. Hence, the aqueous medium can flow either through or around the cylinder or tube. In the latter case with the second reactor, gaseous products will be removed from within the cylindrical membrane. Further-more, such gases, irrespective of whether they pass from or into the cylindrical membrane, can be dissolved in a liquid solvent ha-~ing a high affinity for the gases, i.e., in which the gases have a high degree of solubility. Suitable solven~s for many gases include silicones and fluorocarbons, among others. The use of such a gas solvent usually is neither necessary nor desired and, therefore, is not preferred.

~7~;68 Since the method and p~ocessi~g apparatus 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 jacket having a gas remo~al means attached thereto.
Under normal circumstances, both reacto~s are main-tained at ~mbient tempe~ature. Indeed, the process of the present invention most preferably is carried out at ambi~nt tempera~ure. While process temperatures are critical only to the extent ~hat the microbes present in each reactor remain viable, as a practical matter the process of the present invention will be carried out at a temperature of from about 10C. to about 60C. Xn those instances where an elevated temperature is desired, such elevated temperature usually is applied only to the first, aerobic reactor, in which case the preferred temperature range is from about 30C. to about 35C.
One preferred embodiment of the process of the present invention is illustrated by the examples in which a principal product is methane which is passed through the controlled-pore, hydrophobic inorganic membrane of the second, anaerobic reactor. Alternatively, process conditions and microbe choices can be made which will yield ethanol as a principal product in the liquid effluent emerging from the second reactor.
The present invention also provides an apparatus for the determination of the biochemical oxygen demand (BOD) of a biodegradable organic waste in an aqueous medium. Such apparatus can take either of two configurations or embodi-ments: (1) a sampling and/or sensing means serially connectedto the first, aerobic reactor described hereinbefore, which ~7668 reactor in turn ia serially ~onnected to a sampling and/or sensing means; and (2) a sampling and/or sensing means serially connected to the first, aerobic reactor described hereinbefore, which first reactor is serially connec~ed to the second, anaerobic reactox desc~ibed hereinbefore, which second reactor is serially connected to a sampling and/or sensing means.
As used herein, the term "sampling and/or sensing means" is meant to include a sampling means, a sensing means, and a sampling and sensing means.
Accordingly, the sampling and/or sensing means can be nothing more than a port, fi~ted With, fo~ example, a stopcock or rubber septum, to provide a means for the manual withdrawal of a sample from the waste stream. Alternatively, such sampling means can be an automated sampling device which automatically removes samples of a precise si2e at predeter-mined intervals and stores such samples for future ~andling or analysis.
Examples of suitable sensing means include, among others, dissolved 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 waste-containing aqueous medium which are the result of the biochemical conversions taking place in the apparatus for determining BOD.
As contemplated by the present invention, a sampling and sensing means can be any combination of a sampling means and a sensing means. For example, an automated sampling device can be serially connected to an automated device for determining COD by a chromic acid oxidation procedure.

~ ~1 7 66 ~ ' Other variations and c~mb~nations, however, will be readily apparent to one having ordinary skill in the art.
Finally, the two sampling and/or sensing means need not be physically discrete or separate. That i5, with appropriate connecting and waste stream directing means, a single sampling and/or sensing means ~an be employed in the BOD apparatus of the presen~ invention, and ~uch use is within the scope of the instant disclosure. Thus, when using a single sampling and/or sensing means, the waste ~tream or a portion thereof first is passed through the sampling and/or sensing means.
The waste stream then e~te~s the aerobic reactor. Upon exiting the aerobic reac~or (or the anaerob~c reactor if bot~ reactors are employed), t~e waste stream or a portion thereof is directed to the sampling and/or sensing means by appropriate connecting and directing means which are well known to those ha~ing ordinary skill in the art.
The prese~t ln~ention is urther described, but not limited, by the following examples which illustrate the use of the method and apparatus of the present invention in the treatment of sewage. Unless otherwise stated, all tempera-tures are in degrees Celsius.
The process empLoyed in Examples 1 and 2 is described below, with reference to the drawing.
Sewage 1 i~ pum~ed fr~m container 2 by pump 3 to aerobic reac~r 4 via rubber tubing 5 sealably connected to ~he pump and the aerobic reactor. The aerobic reactor consists of inner glass tube 6 sealable enclosed within glass jacket 7. The inner glass tube contains inorganic carrier 8 such as that described in uOs. Patent No. 4,153,510, 3~

~ 66 ~

which is suitable for thP- accumulation of a biomass. Sewage leaving the aerobic reactor is transported to anaerobic reactor 9 via rubber tubing 10 sealably connected tv both reactors. The anaerobic reactor consists of inorganic membrane 11 and glass jacket 12 having exit port 13. The inorganic membra~e is filled with additional inorganic carrier 8 and is sealably enclosed within the glass jacket.
Rubber tubing 14, sealably connected to the exit port of the jacket, leads to p~mp 15 which removes gas ~methane) from air space 16 enclosed by the jacket. Such gas in turn is collected by any suitable means such as by the displacement of water in an inverted vessel Cnot shown). Sewage effluent 17 then is transported, via rubber tubing 18 sealably con-nected to the anaerobic reactor, to receiving vessel 19.
The sewage employed in each of the examples was obtaine~
from the inlet pipe to the Corning, New York, Municipal Sewage Waste Treatment Pla~t. The sewage was stored at 4-6C. Prior to use, the sewage was filtered through cheese-cloth and glass wool to remove coarse particulate matter.
Sewage was collected either weekly or biweekly.

ExamPle 1 Pump 3 consisted of a Fluid Metering pump, RPlG6CSC
(Fluid Mete~ing, Inc., ~y~ter Ba~, ~.Y.), which was connected to aerobic reactor 4 with a 14-in h length of rubber tubing.
A 20-inch length of rubber tubing was attached to the intake side of the pump and led from a flask containing sewage.
The aerobic reactor consisted of a Pharmacia K16/20 column (Pharmacia Fine Chemicals, Uppsala, Sweden) wi~h water jacket; the water jacket was left vented to the atmosphere. The column was charged with 24 g. of cordierite ~117~f~8 (CGZ) carrier having a pore diameter distribution of 2-9 and an average pore di~uneter of 4.51~l. The carrier was seeded with sewage microbes by 1Owing ~hrough the reactor sludge obtained previously from a municipal anaerobic di~estor.
The inorganic membra~e 11 of anaerobic reactor 9 was a 5ilica membrEn~, prepared in ~cordance wlth known procedures;
see, for example, U.S. Patent Nos. 3,678,144, 3,782,9~2, and 3,827,893. The membrane was appro~imately 18 cm. long with cross-sectional dimensions of 10.5 mm. i.d. a~d 15.5 mm.
o.d. The average pore diamete~ of the membrane was 3500 with a pore diameter di~tribution of 2000-3600~. ~all poroslty was 60 percent and pore volume was 0.89 cc/g. The m~mbrane was rendered hydrophobic by placing ~t in 75 ml. o a ten percent solution of octadecyltrichlorosil~ne in acetone and allowing it to soak overnight. The m~mbrane then was removed from the solution, washed with 500 ml. of acetone, and air-dried.
The membrane was mounted in a Yharmacia K16/20 water jacket by me~s of the ~tandard rubber sealing ring and threaded locking ring and was charged with ten g. of the CG~
carrier. Both reactors together had a total void or fluid volume of about 30 ml.
The two reactors were coupled with about four inches of rubber tubing. One of the ports of the anaerobic reactor jacket was ~ealed by attaching a Qhort pie e of Tygon tubing thereto and elosing the tu~ing by means of a clamp. The other port was attached to a Buchler Polystaltic Pump (Buchler Instruments, Inc., Fort Lee, N.J.) with a length of thick-walled Tygon tubing. Gas evolved ~nd passed through the membrane was collected by the displacement of wa~er in a calibrated cylinder inverted in water-filled, large, shallow *Trade Mark -21-~ 66~

vessel. The rate of gas evolution was observed and the collected gas was analyzed a~ least daily b~ mass spectroscopy.
In addition, the chemical oxygen demand (COD) of the sewage used as feed and the effluent eme~ging from the anaerobic reactor wexe determined periodically b~ standard, well-known colorimetric dichromate oxidation procedures.
The process was run ~or a period of about nine months.
Although data were generated on a dail~ basis, except for COD analyses, weekly averages of the data are presented in Table I; in the table, COD analyses are averaged where more than one analysis was obtained per week.

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Example 7 The procedure of Example 1 was repeated, except that the aerobic reactor was charged with 19 g. of CGZ carrier, the carrier in the aerobic reactor was not seeded, the inorganic membrane of the anaerobic reactor was an alumina mem~rane, and the anaerobic reactor was charged with 18.4 ~.
of the CGZ carrier.
The alumina membrane was prepared in accordance with well-known procedures. Briefly, 300 g. of SA alumina con-taining three percent by weight ~f carbowax was isostatic-ally pressed at 1,758 kg./cm.2 (25,000 psi) in a mold which consisted of a cylindrical mandrel having a diameter of 1.9 cm. and a cylinder with rubber sleeve having an inner diameter of 3.65 cm. The resulting cylindrical tube had the following cross-sectional d~mensions: i.d., 1.9 cm., and o.d., 2.62 cm. The tube was turned on a ~athe to an o.d. of 2.4 cm.
The tube was about 36 cm. in length. The tube then was fired in a furnace as follows: The furnace was heated to 500 (from ambient temperature~ at 50 per hour and held at 500 for two hours. The temperature then was increased to 1550 at a first rate of 50 per hour to 950 and a second rate of 100 per hour to L550, at which temperature the furnace was held for five hours. The furnace then was cooled at 100 per hour to 950, and at 50 per hour to ambient tempera~ure. The resulting alumina controlled-pore membrane had an i.d. of 1.43 cm., an o.d. of 1.75 cm. 9 and a wall thic~ness of 2.0 mm. Pore di~meter distribution was fr~m 3500~ to 4500~, with an average pore di~eter of 4000~.
Wall porosity was 46.8 perce~t and pore volume was 0.22 cc./g. The membrane was rendered hydrophobic by placing it ~1~7~;68 in 50 ml. of acetone containing ten percent octadecyltri-chlorosilane and allowing it to react overni~ht at ambient temperature. The membrane then was removed from 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 1.5 hours.
The data obtained from ~his example are summariæed in Table II, again as weekly averages.

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1~7668 Example 3 The proeedure of Example 1 was repeated with some changes in equipment. The aerobie reactor consisted of a Lab-Crest column, without jacket, 400 x 15 mm. The reactor was charged with 50 g. of CGZ carrier. The anerobic reactor consisted of an outer jacket 31.1 cm. in length and a fritted glass membrane 30.5 cm. in length and 1.6 cm. in diameter.
The membrane, which was fused to the outer Jacket, consisted of three sections of fritted glass tubing of equal length which had been fused together. The total length of the anaerobic reactor was 40.6 cm. The membrane had a pore diameter distribution of 3-6~ and an a~erage pore diameter of 4.5~. The membrane was made hydrophobic by allowi~g it to react with 130 ml. of ten percent octadecyltrichlorosilane in acetone at ambient temperature for about three days. The membrane then was removed from the acetone solution and washed successively with two 130-ml. portions of acetone, two 130-ml. portions of methanol, and a 130-ml. portion of acetone. The membrane was air-dried by aspiration. The anaerobic reactor was charged with 23 g. of CGZ carrier.
The gas pump was a Cole-Parmer Masterflex peristaltic pump.
The results are summarized in Table III. The membsane, however, passed liquid water during the time ~he process was in operation, demonstrating that the pore diameters of the fritted glass membrane in general were too large.

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Example 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 inorganic membrane of the anaerobic reactor. Most preferably, such microbes will be photo-qynthetic ~icrobes, ex~mples of which include, ~mong others Rhodospirillum rubrum, Chromatium Sp., Chlorobium thiosulf-atophilum, loropseud~monas ethylica, Chorella SP.. Scenedesmus SP., lamydomonas Sp., Ankistrodesmus Sp., Chondrus Sp., Corallina Sp., Callilhæmnion Sp., and the like.
-The examples which follow illustrate one embod~ment ofthe B~D apparatus of the present invention.

Example 4 A two-liter reagent bottle with a side arm at the bott~m was connected, ~ia a length of Tygon tubing attached to the side arm, to the inlet port of a Fluid Metering, Inc.
Model RP G-6 pump ~Fluid Metering, Inc., Oyster Bay, New York). The outlet port of the pum~ was attached, again via Tygon tubing, to the bot~om of a vertically-mounted 9 x 150 mm. Fisher and Porter chr~matographic column Cobtained from Arthur H. Thomas Co., Philadelphia, Pa. ~ . The column was-charged with 6.5 g. of the CGZ carrier described in Example 1. The top of the column was connected b~ Tygon ~ubing to the inlet por~ of a cell ha~ing sealably mounted therein ~he dissolYed oxygen sensor of a Di~fusion Ox~gen Analyzer (International Biophysics Corp., Irvine, Cal.). The outlet port of the cell was conne~ted wlth Tygon tubing to a reeeiving vcssel. Another dissolved oxygen sensor was placed in the reagent ~ottle which served as a waste stream reservoir. Each dissolved oxygen sensor was standardized *Trade Mark _ 3 3 _ 1~L~ 7 ~;8 against air-saturated water at 21.9% saturation.
The column was seeded by continuously recirculating a volume of sewage through the column at a flow rate of L
ml./min. for five days. A sterile, standard BOD solution containing 150 mg/litcr each o~ glutamic acid and glucose was passed through the column at 0.37 ml./min. for 24 hours as a preco~ditioning to insure adequate bioaccumNla~ion prior to collecting oxygen uptake data. The standard BOD
solution then was pas~ed through the column or immobilized aerobic microbe reactor. The effluent percent saturation was measured at three different flow rates. In each case, the perce~ saturation of the feed in the reservoir was 21.9% and the effluent percent saturation reading stabilized within 20-~0 min. after cha~ging the flow rate. The results are summarized in Table IV.

TABLE_IV
Oxygen Uptake In An Ae~obic ~ae~
Flow Rate (ml /min.) Effluent ~/O 5aturation 0.19 7a

2.07 18.5 Decreased to 4.5 after an additional 12 hours.

From Table IV, it is apparent that oxygen uptake is inversely proportional to the flow rate. Oxygen uptake, expressed as the percentage of dissolved oxygen consumed, is summarized in TabLe V and was calculate~ in accordance with the following formNl~:

% 2 consumed = Feed % SaF nd-O/Efft,% Sa~ n x 100 TABLE V
Percentage of Dissolved Oxygen Consumed In An Aerobic Reactor BOD Apparatus Flow Rate, ml./min. ~ 2 Consumed 0. 19 68a 0.37 54 2.07 16 alncreased to 79% after an additional 12 hours.

Exam~le 5 The procedure of Example 4 was repeated, except that the c~lumn was seeded with 200 ml. of an overnight tryptic soy broth culture of Escherichia coli (109 ceIls/ml.) and the standard BOD solution was replaced with sterile broth.
A~ter the 24-hour preconditioning period, the effluent pPr-cent saturation was measured ~nd found to be 0%; the broth percent saturation origi~ally was 21~9~/o~ Thus, 10Q% of the dissolved oxygen was consumed.
Examples 4 and 5 clearly demonstrate the feasibility of measuring a difference in an organic waste-containing aqueous medium, T~hich difference is the result of biochemical con-ver~ions (oxidations) taking place in the BOD apparatus aerobic reactor.
Such a measurable differe~ce ~hen is readily correlated to B~D by known procedures. For one example sf such a correlation, see I. Karube et al., Biotechnol. Bioen~., 19, 1535 (1977). Thus, for a given aerobic reactor (or aerobic reactor and anaerobic reactor serially connected), passing standard solutions having varying concentrations of organic ~7~1 material at a given flow rate will yi.eld a set of, for example, oxygen uptake data. The BOD values of such standard solutions can be determined by conventional methods ~o give a set of conventional BOD values. The two sets of data then can be combined in graph fonm to give a standard curve ~or each flow ra~e employed. The BO~ of any organic waste in an aqueous medium then is determined quickly and simply by passi~g such aqueous medium through the BOD apparatus and comparing the data obtained with the appropriate standard curve.

Claims

WHAT IS CLAIMED IS:

1. A method for processing organic waste in an aqueous medium which comprises serially passing an organic waste-containing aqueous medium through a first immobilized microbe reactor and a second immobilized microbe reactor, in which:
A. the first reactor 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 reactor com-prising a controlled-pore, hydrophobic inorganic membrane which contains a porous inorganic support which is suitable for the accumulation of a biomass, in which at least about 90 percent of the pores of the inorganic membrane have diameters of from about 100% to about 10,000.ANG..

2. The method of claim 1 in which the anaerobic reactor is sealably enclosed within a jacket having a gas removal means attached thereto.

3. The method of claim 1 in which the aerobic reactor is maintained at a temperature of from about 10°C. to about 60°C.

4. The method of claim 3 in which the temperature is ambient temperature.

5. The method of claim 3 in which the temperature is from about 30°C. to about 35°C.

6. The method of claim 1 in which the inorganic support of the aerobic reactor is a porous, high surface area inorganic support which is suitable for the accumulation of a high biomass surface within a relatively small volume.

7. The method of claim 6 in which 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 aerobic reactor.

8. The method of claim 6 in which the average diameter of the pores of the inorganic support is in the range of from about 0.8 to about 220µ.

9. The method of claim 8 in which the inorganic support is a cordierite material.

10. The method of claim 9 in which the cordierite inorganic support has a pore diameter distribution of from about 2 to about 9µ, and an average pore diameter of about 4.5µ.

11. The method of claim 1 in which the inorganic support of the anaerobic reactor is a porous, high surface area inorganic support which is suitable for the accumulation of a high biomass surface within a relatively small volume.

12. The method of claim 11 in which 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 is the anaerobic reactor.

13. The method of claim 11 in which the average diameter of the pores of the inorganic support is in the range of from about 0.8 to about 220µ.

14. The method of claim 13 in which the inorganic support is a cordierite material.

15. The method of claim 14 in which the cordierite inorganic support has a pore diameter distribution of from about 2 to about 9µ, and an average pore diameter of about 4.5µ.

16. The method of claim 1 in which the pore diameter range of the pores of the inorganic membrane of the anaerobic reactor is from about 1,500.ANG. to about 6,000.ANG..

17. The method of claim 16 in which the inorganic membrane is composed of a material which is selected from the group consisting of glass, spinel, silica, and alumina.

18. The method of claim 16 in which the membrane is rendered hydrophobic by a post-formation treatment with octadecyltri-chlorosilane.

19. The method of claim 1 in which an additional microbe colony is established on the gas-space side of the inorganic membrane of the anaerobic reactor.

20. The method of claim 1 in which a principal product is methane which is passed through the controlled-pore, hydro-phobic inorganic membrane of the anaerobic reactor.

21. The method of claim 1 in which the principal product is ethanol which is a constituent of the liquid effluent emerging from the anaerobic reactor.

22. An apparatus for processing organic waste in an aqueous medium which comprises a first immobilized microbe reactor serially connected to a second immobilized microbe reactor, in which:
A. the first reactor 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 reactor com-prising a controlled-pore, hydrophobic inorganic membrane which contains a porous inorganic support which is suitable for the accumulation of a biomass.

23. The apparatus of claim 22 in which the anaerobic reactor is sealably enclosed within a jacket having a gas removal means attached thereto.

24. 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 a first immobilized microbe reactor which is serially connected to a second immobilized microbe 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 accu-mulation of a biomass, and B. the second reactor is an anaerobic reactor com-prising a controlled-pore, hydrophobic inorganic membrane which contains a porous inorganic support which is suitable for the accumulation of a biomass.

25 . The apparatus of claim 24 in which two separate sampling and/or sensing means of the same type are employed.

26 . The apparatus of claim 25 in which each sampling and/or sensing means comprises a dissolved oxygen sensor.

27. The apparatus of claim 25 in which each sampling and/or sensing means comprises an ammonium ion sensor.

28. The apparatus of claim 24 in which a single sampling and/lor sensing means is employed.

29. The apparatus of claim 28 in which the sampling and/or sensing means comprises a dissolved oxygen sensor.