CA1108920A - Process of preparing a biomass - Google Patents
Process of preparing a biomassInfo
- Publication number
- CA1108920A CA1108920A CA344,852A CA344852A CA1108920A CA 1108920 A CA1108920 A CA 1108920A CA 344852 A CA344852 A CA 344852A CA 1108920 A CA1108920 A CA 1108920A
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- Prior art keywords
- process according
- reactor
- liquor
- biomass
- microorganisms
- Prior art date
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
- C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
- C12N1/24—Processes using, or culture media containing, waste sulfite liquor
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23K—FODDER
- A23K10/00—Animal feeding-stuffs
- A23K10/10—Animal feeding-stuffs obtained by microbiological or biochemical processes
- A23K10/12—Animal feeding-stuffs obtained by microbiological or biochemical processes by fermentation of natural products, e.g. of vegetable material, animal waste material or biomass
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
- C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
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- Biotechnology (AREA)
- Zoology (AREA)
- Bioinformatics & Cheminformatics (AREA)
- Organic Chemistry (AREA)
- Wood Science & Technology (AREA)
- Genetics & Genomics (AREA)
- Biomedical Technology (AREA)
- Microbiology (AREA)
- Biochemistry (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Tropical Medicine & Parasitology (AREA)
- Virology (AREA)
- General Engineering & Computer Science (AREA)
- General Health & Medical Sciences (AREA)
- Food Science & Technology (AREA)
- Sustainable Development (AREA)
- Animal Husbandry (AREA)
- Physiology (AREA)
- Molecular Biology (AREA)
- Micro-Organisms Or Cultivation Processes Thereof (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A biomass which is made of a mixed culture of micro-organisms is produced by bio-degradation of waste liquor from bisulfite pulping. Under non-aseptic conditions, and using nutrients with the liquor, the latter is treated with acclimatized microorganisms which are derived from sewage. The biomass which is obtained as a result of the multiplication of the microorganisms on the liquor can be separated, dried and pulverized to give a substance which can be used as feed for animals.
A biomass which is made of a mixed culture of micro-organisms is produced by bio-degradation of waste liquor from bisulfite pulping. Under non-aseptic conditions, and using nutrients with the liquor, the latter is treated with acclimatized microorganisms which are derived from sewage. The biomass which is obtained as a result of the multiplication of the microorganisms on the liquor can be separated, dried and pulverized to give a substance which can be used as feed for animals.
Description
This invention relates to a process for preparing a biomass. More particularly, the invention relates to a process whereby a rnixture containing fermentable materials, such as carbohydrates, more particularly sulfite waste liquor, is allowed to be bio-degraded with microorganisms derived from domestic sewage to give a biomass which can he used for feed-ing animalsO
Small bisulfite and siulfite mills are known for their water pollution problems. These mills normally produce less than 300 tons per day of pulpo ~le water pollution load in the effluents from these mills results mainly from the wood carbohydrates dissolved in the waste pulping liquors-which are presently discharged to the receiving water~.
On the other hand, the various governments are soon due to implement water pollution regulations for pulp and paper industries. These regulations will be so stringent in the very near future that mills wi]l have to treat their effluents. For exarnple, the Quebec Government's water pollution regulation for bisulfite pulp mills, which will come into force by the end of 1980, will require that an existing mill mus~ remove 65% of BOD5 in its combined ef~luent before discharging. ~ecause of their small capaci~y in pulp production, mosit mills cannot economically adopt the conventional treatment system to recover cheMicals ancl heat from their waste liquors, asi most kra~t mill~ do at present.
~he biomass derived from pure cul~ure such as torula yeast produced from waste sulfite liquor, has long been used in hu-man food~ [Scrimshaw, N.S., "Single-Cell Protein" ed.: Mateles, R.I. and Tannenbaurn, S.R., P. 5, MIT Press, Cambridge, Mass.
(1968)] and animal feed [Peppler, J.H., "Single-Cell Protein", ed.: Mateles, R.I. and Tannenbaurn, S.R., p. 238, MIT Press Cambridge, Mass. (1968)~.
It is also well known that feeds used for animals can be replaced totally or partially with pure culture biomass (microfungi) resulting from the bio-degradation of different sulfite waste liquors. All these processes require careful preparation and purification of the microorganisms. Also, the biological reaction and the other operations must be carried out under rigid control and aseptic conditions, in order to prevent external contamination.
It i5 also well known that throughout the world there is a shortage of animal feeds and since this shortage problem should become more serious in the future, it would seem inter-esting to solve this problem, at least partially, by using as a portion of the feed, a biomass resulting from the bio-degra-dation of waste pulping liquors, especially where the pulp and paper industry produces an extremely large amount of waste li-quor. I~his shortage of animal feed and the excess of waste pulping llquors are especially true for Eastern Canada.
With this view in mind, the present invention aims at a process for preparing a biomass which comprises:
a) providing liquor containing refuse fermentable materials;
b~ providing a reactor containing microorganisms derived from sewage;
c) rnixing said liquor with nutrients, d) inducing an aerobic condition with ~aid micro~
organisms;
e) feeding said liquor containing nutrients into said reactor and rnixing it therein with said microorganisms;
f~ allowing bio-degradation of said liquor by means of said microorganisms and their multiplication thereby 1'` ~ ' ~ 2-producing a biomass-containing body.
In other words, it can be stated that the liquor which is used with nutrients is treated under non-aseptic conditions with acclimatized microorganisms which are derived frorn sewage.
Although any liquor containing refuse fermentable materials can be used, it is of course much more interesting, on an industrial basis, to use one containing carboh~drates, more particularly sulfite waste liquor which is thrown away in most cases and can cause serious pollution problems. -When the solid content of the liquor is too high, such as when there i5 over 10% dissolved solids, the sulfite spent waste liquor may be diluted with water~
For a more effective and practical operation of the process accordin~ to the invention, it is preferable to use acclimatized microorganisms. Ihis can be achieved by contact-ing microorganisms from sewage with sulfite waste liquor for a period of time varying between 10 and 20 days.
Although any nutrients known to those skilled in the art may be added to the liquor before subjecting the latter to bio-degradation with the preferably acclimatized micro-organisms, it is preferred to use nitrogen-, phosphorus- and potassium-containing nutrients. More preferably, the nutrients supply nitrogen, phosphorus and potassium in a weight ratio of about 12:2:1.
It is preferred to use amrnonia and KH2P0~ as the source of nitrogen, phosphorus and potassiurn nutrients.
Of course, other nutrients, such as (NH4)2S04, K2HP04 and the like well known to those skilled in the art may also be used Preferably, anti-foaming conditions should prevail in the reactor, and these conditions may be obtained, for exam-ple,by adding an anti-foaming agent such as the one manufactured and sold by Dow Corning under the trade mark Antifoarn FG-10.
. )~
: ' ' : . .. . ..
It is recommended to have an aerobic condition in the reactor and, for this purpose, for example, oxygen is conti-nuously introduced into the fermentation rnix~ure in such a way as to be continuously dissolved in the ranye between about 0.2 to 2~1 ppm oxygen. In general, the concentration of oxy-gen in the mixture should be about 1~5 ppm.
For example, the oxygen may be introduced by adding air to the reactor, either by resorting to mechanical means, or by bubbling or the like, as it is well known to those skilled in the art.
In order to provide an aerobic condition, it may be easier to aerate a high capacity fermentation reactor than a small reactor because of the longer residence time of the air bubbles within the suspenslon.
As pointed out above, the ac7ldition of an anti foaming agent or the use of anti-foaming conditions are helpful to maintain steady-state operating conditic;ns.
In order to obtain good yields in biomass production, it has been found that the pII in the xeactor should preferably be adjusted to vary between about 4 and 7.
Adjusting the pH can be carried out by adding any suitable agent. It has been found that an alkaline agent such as sodium hydroxide, potassium hydroxide and ammonia can be used, ammonia being preferred.
The microorganism3 consume the components oE the li-quor in a preEerential manner, i.e. sorne nutrients which are more difficult to dige~t are :Le~t aside. For example, the Liynosulfonates are almost not bio-degraded by the mi~roorga-nisms. In orcler to achieve the best possible results, the residence of the liquor in the reactor has been found to be preferably about 72 hours, As a matter of fact, it has ~.
been found that the microorganisms become acclimatized to the sulfite waste liquor as a result of some competition between the various microorganisms which are derived from domestic sewage. For these reasons, under the conditions of the reaction, development of predominant classe3 of microorganisms will take place which has a definite influence on the nature of the biomass which is obtained in final analysis.
Although a variation in temperature does not have a harmful influence on the characteristics and properties of the biomass which i5 obtained by the process according to the invention, it has been found that in order to have the best suitable conditions for producing good yields o biomass of good quality the temperature should be adjusted to between about 15 to 40~C, preferably between about 20 and 22~C, otherwise the residence time of the liquor and the nature of the microorganisms in the reactor will have to be substantially adjusted. More preferably, the temperature in the reactor should be maintained at about 20C.
In accordance with a preferred embodiment of the in-vention, once a biomass-containing body is discharged from the reactor, the biomass is dewatered, and this may be followed by washing, sterilization, drying and grinding.
The microorganisms which are derived from domestic sewage usually comprise a mixture of bacteria, yeasts and mi.crofungi.
Broadly stated, the product obtained by the process according to the invention conta.in~ when dried:
water 0.1 - 6 weight percent proteins 25 - 50 "
minerals 0.1 - 5 vitarnins0.001 - .~ " "
.,, .... ..... , , ~,,. " .,,, ,. .. " ,.. .~ .. ~.......... .
r~
The invention will be illustrated by means of the enclosed drawings, which are given only for the purpose of illustration. In the drawings, Figure l is a schematic representation of the system used to produce dry biomass.
I~he in~ention will now be further illustrated by means of the following example which should be read in con-junction with the annexed drawings.
PRODUCTION OF SLUDGE SOLIDS ( BIOMASS ) Waste liquor An industrial waste liquor from high-yield sodium bisulfite pulping was used to produce the sludge solids. The routine cooking conditions used in the pulping process are shown in Table l.
TABLE I
ROUTINE COOKING CONDITIONS USED IN HIGH YIELD BIStJLFITE
PULP ING
_ _ . _ Wood species, wt. /O 94-93 softwood and 6-7 hardwood Fresh liquor/wood, w/w 4 : l Total S02, wt. % 2.9 Cooking time at maximum temperature (165C) 6 h pH 4 - 5 Yield, Wt.% 70 - 75 _ _ _ . . . (pll,l,p) The dry solids in this liquor normally contain about 50% sodium lignosulfonates and 40% carbohydrates expressed as apparent glucose. The content of lignosulfonates was deter-mined with W absorption at 280 nrn, and that of apparent glu-cose by the anthrone reaction as described by Lo, S.N. and r~ ~
Garceau, J.J., Can. J. Chem. Eng. 53,582 ~1975). 'I~is liquor contains 6% to 10% dissolved solids and has a BOD5 approxi-mately equal to 0.33 g 02/g dissolved solids.
Conversion of carbohydrates in liquor to biomass In a preparation tank 1, waste liquor was first mixed with nutrients, K2HP04 ancl (~4)2S04, to achieve a ratio of BOD5 : N : P = 100 : 5 : 1 in the feed, if necessary, the liquor was diluted with water in order to obtain 6% liquor so-lids~ The pH in the feed was adjusted to 7 with ~aOH. The fortified liquor was fed continuously via a feed tank 2 into an aerated, cylindrical tank reactor 3 having a working volume of 400 1, simultaneously, the reactor content was discharged at a flow rate equal to that of the feed. The reactor contain-ing acclimatized microorganisms originating from a muni-cipal sewage treatment plant was operated under nonaseptic conditions at pH's between 4 and 7. The adjustment of pH to 7 was carried out manually, once per day, with NaOH solution. Ihe foam was controlled with Dow Corning antifoam FG-10* (food grade) dispersed in a large quantity of water by means of an antifoam sprayer. During operations, no difference was observed between the effluent and feed temperatures, which were equal to room temperature maintained ~ -at 20 - l~C~ Air, which also provided good mixing in the reactor, was fed to -the reactor through a perfora-ted poly-ethylene tube of 12.7 ~n I.D. Th.is tube, ln form of a coil with several turns, was fixed on the reactor bottom. Dissolved oxygen was measured with a Yellow Sprinc~3 Instrument (YSI) oxygen meter, model 57. The reactox output contained approxi-mately 11 y dry biomass/1. The recovery of this hiomass was first carried out by sedimentation in settling tank 4, then by batch-wise centrifugation at 5 which produced a paste con-* Trade Mark taining 20 to 25% dry matter.
The sterilization and washing of this paste, which had been placed in a cotton bag, was carried out at 6 simultaneous-ly by holding the bag in boiling water for at least 30 min. The volume ratio of boiling water to paste was greater than 10. Af-ter allowing it to drip for a few hours the pagte was dried over-night in a vacuum oven 7 at about 65C. The driecl product was then ground into powder at 8. The product was beige and had a very slightly salty taste and a very mild pleasant odour.
Table 2 shows the operating conditlons used in the conversion of carbohydrates into a dry biomass of a mixed culture from natural origin. In Table 2 it can be noticed that a 6% liquor solids content and a 72-h hydraulic retention time or sludge age were used in the operation.
,:
~ ; -8 r -~
r3 OPERATING CONDI~IONS USED IN TME CONVERSION OF C~RBOHYDRArrES
TO DRY BIOMASS
_ _ ~
Solids content of waste liquor, wt. % 6 Density of waste liquor, kg/m 1026 Carbohydrates concentration in feed, g/l* 24.6 pH of feed 7 100 5 : 1 Reactor vol~ne, 1 400 Operating temperature, C 20 Hydraulic retention time, h 72 Mass concentration of microorganisms in the reactor, g/l 10 to 11 Food to microorganisms, F/M, g carbohydrates in feed/(g biomass in reactor) . d 0.78 Concentration of dissolved 2 in the reactor, ~ 1.5 pH in the reactor 4 to 7 Antifoaming agent, made of Dow Corning anti-foam FG-10 and water, antifoam FG-10 :
water (v/v) 8 : 1000 Frequency of spraying antifoaming agent, min 1 ~nount of antifoam agant sprayed in each time, cm3 2.6 Total volume of the sedimentation unit, (two equal units in series) 1 80 Detention time in each settling unit, h 7.2 Biomass content of the sediment in the first settling unit, wt. % 1.8 to 2.2 Biornass content of the paste obtained after centrifugation at 4,000 ~/min for 4 rnin, wt.~/~ 20 to 25 Washiny water : paste, ~/v 10 : 1 Time of sterilization at 100C, rnin 30 Drying temperature under approximately 100 kN m 2 vacuum, C 60 to 70 * expressed as apparent glucose.
g_ .
The microbial flora of the product according to the invention consisted of a mixed culture of rnicxoorganisms, originating from those present in the mixed liquor of -the conventional domestic sewage -treatment process, i.e~ -the acti-vated sludge process. Before putting the production system into operation, sterilization experiments were run to determine the time needed to kill in the produced biomass all the vegeta-tive cells and spores, both aerobic and anaerobic. Experiment-al results, obtained under aerobic and anaerobic conditions revealed that boiling at 100C for 20 min. had killed both kinds of microorganisms and the spores. In order to obtain a safer final product the paste from the centrifugation step was then sterilized by heating for 30 min. at 100C.
The overall composition of the product according to the invention is presented in Table 3.
OVERALL COMPOSITION OF MIXED-CULTURE MICROORGANISMS
Nitrogen-containing material or crude protein........ 37.9 wt. %
Moisture............................................. 4.4 wt. %
20 Ash................. ~................... ~.............. 4.1 wt. %
Fat............... . .................................. l wt. %
Carbohydrate, as apparent glucose 47.5 wt. %
Minerals_ mg/(kq dry matter) . . _ .
Ca 1020 Fe _ 130 . .
Mg 127.6 Na 11900 .. . .. . .. . .. ..... . .
I~ere was found no trace of mercury or arsenic.
; The amino acid cont~nts of the product according to .
,~
i_"
~. ~ ,.
the invention are shown in Table 4.
AMINO ACID COMPOSITION (q/16q NITROGEN) Alanine 7~07 Arginine 4.72 Aspartic acid 8.04 Cy~tine Glutamic acid 11.82 Glycine 4.48 Histidine 2,48 ~ -Isoleucine 4.24 Leucine 8.73 -Lysine 7.92 Methionine 3~06 -~
Norleucine 7.91 Phenylalanine 5.64 Proline 3.89 Serine 4.8 Threonine 3.72 Triptophan Tyrosine 8.44 Valine 4-3 Some vi~amins have been measured. Their values are presented in Table 5.
; VITAMIN CO~TENTS OF MIXED CUETURE MICROORGANISMS
Vitamin m~/k~ drY matter Thiamine.............. ,.......................... 5~66 Riboflavine........... ..................~........ 22.5 30 ~iacin.... ,..................................... llO
Folic acid......................................... 2.81 ~, -1:1.-.
t~
rrhe protein quality of the product according to the invention was evaluated with young rats, using AOAC' 5 method for PER determlnation. (Horwitz, W~, ed. "Official Methods of Analysis", 12th Edi~ion (1975), Assoc. Official Anal. ~emists, Washington, D.C. In the evaluation, ten youny male rats were used in each group, thirty rats in total, the assay lasted four weeks. In addition to using the product as the sole source of protein, the diet of the assay yroup II was supple-mented with 0.3 wt. % methionine. Table 6 gives the average PER values obtained for the casein group and the two assay groups. For comparison, these values were adjusted to an assumed value of 2.5 for casein. Statistically, these values are significantly different at a probability of less than O ~ 01 .
These PER results show that the protein contained in the product of the invention is short of sGme essential amino acids, as indicated by the very low PER of 0~24 obtained from assay group I. ~Iowever, when -the same protein was slightly supplemented with methionine (0.3 wt.%), it gave a PER of 2.05, close to that of casein for which the PER equals
Small bisulfite and siulfite mills are known for their water pollution problems. These mills normally produce less than 300 tons per day of pulpo ~le water pollution load in the effluents from these mills results mainly from the wood carbohydrates dissolved in the waste pulping liquors-which are presently discharged to the receiving water~.
On the other hand, the various governments are soon due to implement water pollution regulations for pulp and paper industries. These regulations will be so stringent in the very near future that mills wi]l have to treat their effluents. For exarnple, the Quebec Government's water pollution regulation for bisulfite pulp mills, which will come into force by the end of 1980, will require that an existing mill mus~ remove 65% of BOD5 in its combined ef~luent before discharging. ~ecause of their small capaci~y in pulp production, mosit mills cannot economically adopt the conventional treatment system to recover cheMicals ancl heat from their waste liquors, asi most kra~t mill~ do at present.
~he biomass derived from pure cul~ure such as torula yeast produced from waste sulfite liquor, has long been used in hu-man food~ [Scrimshaw, N.S., "Single-Cell Protein" ed.: Mateles, R.I. and Tannenbaurn, S.R., P. 5, MIT Press, Cambridge, Mass.
(1968)] and animal feed [Peppler, J.H., "Single-Cell Protein", ed.: Mateles, R.I. and Tannenbaurn, S.R., p. 238, MIT Press Cambridge, Mass. (1968)~.
It is also well known that feeds used for animals can be replaced totally or partially with pure culture biomass (microfungi) resulting from the bio-degradation of different sulfite waste liquors. All these processes require careful preparation and purification of the microorganisms. Also, the biological reaction and the other operations must be carried out under rigid control and aseptic conditions, in order to prevent external contamination.
It i5 also well known that throughout the world there is a shortage of animal feeds and since this shortage problem should become more serious in the future, it would seem inter-esting to solve this problem, at least partially, by using as a portion of the feed, a biomass resulting from the bio-degra-dation of waste pulping liquors, especially where the pulp and paper industry produces an extremely large amount of waste li-quor. I~his shortage of animal feed and the excess of waste pulping llquors are especially true for Eastern Canada.
With this view in mind, the present invention aims at a process for preparing a biomass which comprises:
a) providing liquor containing refuse fermentable materials;
b~ providing a reactor containing microorganisms derived from sewage;
c) rnixing said liquor with nutrients, d) inducing an aerobic condition with ~aid micro~
organisms;
e) feeding said liquor containing nutrients into said reactor and rnixing it therein with said microorganisms;
f~ allowing bio-degradation of said liquor by means of said microorganisms and their multiplication thereby 1'` ~ ' ~ 2-producing a biomass-containing body.
In other words, it can be stated that the liquor which is used with nutrients is treated under non-aseptic conditions with acclimatized microorganisms which are derived frorn sewage.
Although any liquor containing refuse fermentable materials can be used, it is of course much more interesting, on an industrial basis, to use one containing carboh~drates, more particularly sulfite waste liquor which is thrown away in most cases and can cause serious pollution problems. -When the solid content of the liquor is too high, such as when there i5 over 10% dissolved solids, the sulfite spent waste liquor may be diluted with water~
For a more effective and practical operation of the process accordin~ to the invention, it is preferable to use acclimatized microorganisms. Ihis can be achieved by contact-ing microorganisms from sewage with sulfite waste liquor for a period of time varying between 10 and 20 days.
Although any nutrients known to those skilled in the art may be added to the liquor before subjecting the latter to bio-degradation with the preferably acclimatized micro-organisms, it is preferred to use nitrogen-, phosphorus- and potassium-containing nutrients. More preferably, the nutrients supply nitrogen, phosphorus and potassium in a weight ratio of about 12:2:1.
It is preferred to use amrnonia and KH2P0~ as the source of nitrogen, phosphorus and potassiurn nutrients.
Of course, other nutrients, such as (NH4)2S04, K2HP04 and the like well known to those skilled in the art may also be used Preferably, anti-foaming conditions should prevail in the reactor, and these conditions may be obtained, for exam-ple,by adding an anti-foaming agent such as the one manufactured and sold by Dow Corning under the trade mark Antifoarn FG-10.
. )~
: ' ' : . .. . ..
It is recommended to have an aerobic condition in the reactor and, for this purpose, for example, oxygen is conti-nuously introduced into the fermentation rnix~ure in such a way as to be continuously dissolved in the ranye between about 0.2 to 2~1 ppm oxygen. In general, the concentration of oxy-gen in the mixture should be about 1~5 ppm.
For example, the oxygen may be introduced by adding air to the reactor, either by resorting to mechanical means, or by bubbling or the like, as it is well known to those skilled in the art.
In order to provide an aerobic condition, it may be easier to aerate a high capacity fermentation reactor than a small reactor because of the longer residence time of the air bubbles within the suspenslon.
As pointed out above, the ac7ldition of an anti foaming agent or the use of anti-foaming conditions are helpful to maintain steady-state operating conditic;ns.
In order to obtain good yields in biomass production, it has been found that the pII in the xeactor should preferably be adjusted to vary between about 4 and 7.
Adjusting the pH can be carried out by adding any suitable agent. It has been found that an alkaline agent such as sodium hydroxide, potassium hydroxide and ammonia can be used, ammonia being preferred.
The microorganism3 consume the components oE the li-quor in a preEerential manner, i.e. sorne nutrients which are more difficult to dige~t are :Le~t aside. For example, the Liynosulfonates are almost not bio-degraded by the mi~roorga-nisms. In orcler to achieve the best possible results, the residence of the liquor in the reactor has been found to be preferably about 72 hours, As a matter of fact, it has ~.
been found that the microorganisms become acclimatized to the sulfite waste liquor as a result of some competition between the various microorganisms which are derived from domestic sewage. For these reasons, under the conditions of the reaction, development of predominant classe3 of microorganisms will take place which has a definite influence on the nature of the biomass which is obtained in final analysis.
Although a variation in temperature does not have a harmful influence on the characteristics and properties of the biomass which i5 obtained by the process according to the invention, it has been found that in order to have the best suitable conditions for producing good yields o biomass of good quality the temperature should be adjusted to between about 15 to 40~C, preferably between about 20 and 22~C, otherwise the residence time of the liquor and the nature of the microorganisms in the reactor will have to be substantially adjusted. More preferably, the temperature in the reactor should be maintained at about 20C.
In accordance with a preferred embodiment of the in-vention, once a biomass-containing body is discharged from the reactor, the biomass is dewatered, and this may be followed by washing, sterilization, drying and grinding.
The microorganisms which are derived from domestic sewage usually comprise a mixture of bacteria, yeasts and mi.crofungi.
Broadly stated, the product obtained by the process according to the invention conta.in~ when dried:
water 0.1 - 6 weight percent proteins 25 - 50 "
minerals 0.1 - 5 vitarnins0.001 - .~ " "
.,, .... ..... , , ~,,. " .,,, ,. .. " ,.. .~ .. ~.......... .
r~
The invention will be illustrated by means of the enclosed drawings, which are given only for the purpose of illustration. In the drawings, Figure l is a schematic representation of the system used to produce dry biomass.
I~he in~ention will now be further illustrated by means of the following example which should be read in con-junction with the annexed drawings.
PRODUCTION OF SLUDGE SOLIDS ( BIOMASS ) Waste liquor An industrial waste liquor from high-yield sodium bisulfite pulping was used to produce the sludge solids. The routine cooking conditions used in the pulping process are shown in Table l.
TABLE I
ROUTINE COOKING CONDITIONS USED IN HIGH YIELD BIStJLFITE
PULP ING
_ _ . _ Wood species, wt. /O 94-93 softwood and 6-7 hardwood Fresh liquor/wood, w/w 4 : l Total S02, wt. % 2.9 Cooking time at maximum temperature (165C) 6 h pH 4 - 5 Yield, Wt.% 70 - 75 _ _ _ . . . (pll,l,p) The dry solids in this liquor normally contain about 50% sodium lignosulfonates and 40% carbohydrates expressed as apparent glucose. The content of lignosulfonates was deter-mined with W absorption at 280 nrn, and that of apparent glu-cose by the anthrone reaction as described by Lo, S.N. and r~ ~
Garceau, J.J., Can. J. Chem. Eng. 53,582 ~1975). 'I~is liquor contains 6% to 10% dissolved solids and has a BOD5 approxi-mately equal to 0.33 g 02/g dissolved solids.
Conversion of carbohydrates in liquor to biomass In a preparation tank 1, waste liquor was first mixed with nutrients, K2HP04 ancl (~4)2S04, to achieve a ratio of BOD5 : N : P = 100 : 5 : 1 in the feed, if necessary, the liquor was diluted with water in order to obtain 6% liquor so-lids~ The pH in the feed was adjusted to 7 with ~aOH. The fortified liquor was fed continuously via a feed tank 2 into an aerated, cylindrical tank reactor 3 having a working volume of 400 1, simultaneously, the reactor content was discharged at a flow rate equal to that of the feed. The reactor contain-ing acclimatized microorganisms originating from a muni-cipal sewage treatment plant was operated under nonaseptic conditions at pH's between 4 and 7. The adjustment of pH to 7 was carried out manually, once per day, with NaOH solution. Ihe foam was controlled with Dow Corning antifoam FG-10* (food grade) dispersed in a large quantity of water by means of an antifoam sprayer. During operations, no difference was observed between the effluent and feed temperatures, which were equal to room temperature maintained ~ -at 20 - l~C~ Air, which also provided good mixing in the reactor, was fed to -the reactor through a perfora-ted poly-ethylene tube of 12.7 ~n I.D. Th.is tube, ln form of a coil with several turns, was fixed on the reactor bottom. Dissolved oxygen was measured with a Yellow Sprinc~3 Instrument (YSI) oxygen meter, model 57. The reactox output contained approxi-mately 11 y dry biomass/1. The recovery of this hiomass was first carried out by sedimentation in settling tank 4, then by batch-wise centrifugation at 5 which produced a paste con-* Trade Mark taining 20 to 25% dry matter.
The sterilization and washing of this paste, which had been placed in a cotton bag, was carried out at 6 simultaneous-ly by holding the bag in boiling water for at least 30 min. The volume ratio of boiling water to paste was greater than 10. Af-ter allowing it to drip for a few hours the pagte was dried over-night in a vacuum oven 7 at about 65C. The driecl product was then ground into powder at 8. The product was beige and had a very slightly salty taste and a very mild pleasant odour.
Table 2 shows the operating conditlons used in the conversion of carbohydrates into a dry biomass of a mixed culture from natural origin. In Table 2 it can be noticed that a 6% liquor solids content and a 72-h hydraulic retention time or sludge age were used in the operation.
,:
~ ; -8 r -~
r3 OPERATING CONDI~IONS USED IN TME CONVERSION OF C~RBOHYDRArrES
TO DRY BIOMASS
_ _ ~
Solids content of waste liquor, wt. % 6 Density of waste liquor, kg/m 1026 Carbohydrates concentration in feed, g/l* 24.6 pH of feed 7 100 5 : 1 Reactor vol~ne, 1 400 Operating temperature, C 20 Hydraulic retention time, h 72 Mass concentration of microorganisms in the reactor, g/l 10 to 11 Food to microorganisms, F/M, g carbohydrates in feed/(g biomass in reactor) . d 0.78 Concentration of dissolved 2 in the reactor, ~ 1.5 pH in the reactor 4 to 7 Antifoaming agent, made of Dow Corning anti-foam FG-10 and water, antifoam FG-10 :
water (v/v) 8 : 1000 Frequency of spraying antifoaming agent, min 1 ~nount of antifoam agant sprayed in each time, cm3 2.6 Total volume of the sedimentation unit, (two equal units in series) 1 80 Detention time in each settling unit, h 7.2 Biomass content of the sediment in the first settling unit, wt. % 1.8 to 2.2 Biornass content of the paste obtained after centrifugation at 4,000 ~/min for 4 rnin, wt.~/~ 20 to 25 Washiny water : paste, ~/v 10 : 1 Time of sterilization at 100C, rnin 30 Drying temperature under approximately 100 kN m 2 vacuum, C 60 to 70 * expressed as apparent glucose.
g_ .
The microbial flora of the product according to the invention consisted of a mixed culture of rnicxoorganisms, originating from those present in the mixed liquor of -the conventional domestic sewage -treatment process, i.e~ -the acti-vated sludge process. Before putting the production system into operation, sterilization experiments were run to determine the time needed to kill in the produced biomass all the vegeta-tive cells and spores, both aerobic and anaerobic. Experiment-al results, obtained under aerobic and anaerobic conditions revealed that boiling at 100C for 20 min. had killed both kinds of microorganisms and the spores. In order to obtain a safer final product the paste from the centrifugation step was then sterilized by heating for 30 min. at 100C.
The overall composition of the product according to the invention is presented in Table 3.
OVERALL COMPOSITION OF MIXED-CULTURE MICROORGANISMS
Nitrogen-containing material or crude protein........ 37.9 wt. %
Moisture............................................. 4.4 wt. %
20 Ash................. ~................... ~.............. 4.1 wt. %
Fat............... . .................................. l wt. %
Carbohydrate, as apparent glucose 47.5 wt. %
Minerals_ mg/(kq dry matter) . . _ .
Ca 1020 Fe _ 130 . .
Mg 127.6 Na 11900 .. . .. . .. . .. ..... . .
I~ere was found no trace of mercury or arsenic.
; The amino acid cont~nts of the product according to .
,~
i_"
~. ~ ,.
the invention are shown in Table 4.
AMINO ACID COMPOSITION (q/16q NITROGEN) Alanine 7~07 Arginine 4.72 Aspartic acid 8.04 Cy~tine Glutamic acid 11.82 Glycine 4.48 Histidine 2,48 ~ -Isoleucine 4.24 Leucine 8.73 -Lysine 7.92 Methionine 3~06 -~
Norleucine 7.91 Phenylalanine 5.64 Proline 3.89 Serine 4.8 Threonine 3.72 Triptophan Tyrosine 8.44 Valine 4-3 Some vi~amins have been measured. Their values are presented in Table 5.
; VITAMIN CO~TENTS OF MIXED CUETURE MICROORGANISMS
Vitamin m~/k~ drY matter Thiamine.............. ,.......................... 5~66 Riboflavine........... ..................~........ 22.5 30 ~iacin.... ,..................................... llO
Folic acid......................................... 2.81 ~, -1:1.-.
t~
rrhe protein quality of the product according to the invention was evaluated with young rats, using AOAC' 5 method for PER determlnation. (Horwitz, W~, ed. "Official Methods of Analysis", 12th Edi~ion (1975), Assoc. Official Anal. ~emists, Washington, D.C. In the evaluation, ten youny male rats were used in each group, thirty rats in total, the assay lasted four weeks. In addition to using the product as the sole source of protein, the diet of the assay yroup II was supple-mented with 0.3 wt. % methionine. Table 6 gives the average PER values obtained for the casein group and the two assay groups. For comparison, these values were adjusted to an assumed value of 2.5 for casein. Statistically, these values are significantly different at a probability of less than O ~ 01 .
These PER results show that the protein contained in the product of the invention is short of sGme essential amino acids, as indicated by the very low PER of 0~24 obtained from assay group I. ~Iowever, when -the same protein was slightly supplemented with methionine (0.3 wt.%), it gave a PER of 2.05, close to that of casein for which the PER equals
2.5.
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BIOLOGICAL EVALUATION OF PROTEIN 9UALITY:
.
PROTEIN-E~FICIENCY-RATIO*
-ControlAssay Assay ~roup qroup I qrou~ II**
Average final weight, g 138.6 49.9 115.1 Average initial weight, g 45.7 45.9 44.~
Average weight gain, g 92.8 A4.0 B 70.3 A
Feed intake, g 285.5 A127~0 B271.8 A
Protein intake, g 30.3 A13.0 B28~0 A
Protein efficiency ratio, PER 3~06 A 0.3 B 2.51 C
Adjusted PER 2.5 A 0.24 B 2.05 C
_ * Ten rats in each group and four-week assay duration.
** The diet of this group was supplemented with 0.3 wt.%
methionine tA, B, C) : Values in the same row with the same letter are not significantly different at P ~ 0.01.
Tests made with chicken During 4 weeks, young broiler chickens were fed with two diets containing equivalent quantities of protein at maxi-mum possible replacement levels derived from standard soya flour and from biomass. The chickens were later slaughtered, dressed and cooked. The weight gains of the chicken were ` statistically the same with both diets. Their carcass and meat were found to be satisfactory upon veterinary inspection.
When cooked the meat of both types of chicken was found to be equally satisfactory with respect to flavour and ~enderness.
\
~ -~.3-
L~ r ~
~;~ .
' "~ " ,' ' ' ' . , 2~
BIOLOGICAL EVALUATION OF PROTEIN 9UALITY:
.
PROTEIN-E~FICIENCY-RATIO*
-ControlAssay Assay ~roup qroup I qrou~ II**
Average final weight, g 138.6 49.9 115.1 Average initial weight, g 45.7 45.9 44.~
Average weight gain, g 92.8 A4.0 B 70.3 A
Feed intake, g 285.5 A127~0 B271.8 A
Protein intake, g 30.3 A13.0 B28~0 A
Protein efficiency ratio, PER 3~06 A 0.3 B 2.51 C
Adjusted PER 2.5 A 0.24 B 2.05 C
_ * Ten rats in each group and four-week assay duration.
** The diet of this group was supplemented with 0.3 wt.%
methionine tA, B, C) : Values in the same row with the same letter are not significantly different at P ~ 0.01.
Tests made with chicken During 4 weeks, young broiler chickens were fed with two diets containing equivalent quantities of protein at maxi-mum possible replacement levels derived from standard soya flour and from biomass. The chickens were later slaughtered, dressed and cooked. The weight gains of the chicken were ` statistically the same with both diets. Their carcass and meat were found to be satisfactory upon veterinary inspection.
When cooked the meat of both types of chicken was found to be equally satisfactory with respect to flavour and ~enderness.
\
~ -~.3-
Claims (30)
1. Process for preparing a biomass which comprises:
a) providing a liquor containing refuse fermentable materials;
b) providing a reactor containing microorganisms derived from sewage;
c) mixing said liquor with nutrients;
d) inducing an aerobic condition with said micro-organisms;
e) feeding said liquor containing nutrients into said reactor and mixing it therein with said micro-organisms;
f) allowing bio-degradation of said liquor by means of said microorganisms and their multiplication thereby pro-ducing a biomass-containing body.
a) providing a liquor containing refuse fermentable materials;
b) providing a reactor containing microorganisms derived from sewage;
c) mixing said liquor with nutrients;
d) inducing an aerobic condition with said micro-organisms;
e) feeding said liquor containing nutrients into said reactor and mixing it therein with said micro-organisms;
f) allowing bio-degradation of said liquor by means of said microorganisms and their multiplication thereby pro-ducing a biomass-containing body.
2. Process according to claim 1, wherein said refuse fermentable materials comprise carbohydrate-based materials.
3. Process according to claim 1, wherein said liquor containing refuse fermentable materials comprise sulfite waste liquor.
4. Process according to claim 1, wherein said reactor contains acclimatized microorganisms derived from sewage.
5. Process according to claim 1, which comprises mixing said liquor with nitrogen-, phosphorus-, and potassium-containing nutrients.
6. Process according to claim 5, wherein said nutrients supply nitrogen, phosphorus and potassium in a weight ratio of about 12 : 2 : 1.
7. Process according to claim 1, which comprises mixing said liquor with nutrients comprising KH2PO4 and NH3.
8. Process according to claim 5, which further comprises providing anti-foaming conditions in said reactor.
9. Process according to claim 8, wherein said anti-foaming conditions are obtained by adding an anti-foaming agent to said reactor.
10. Process according to claim 9, wherein said anti-foaming agent comprises Dow Corning antifoam FG-10.
11. Process according to claim 1, in which the pH in the reactor varies between 4 and 7.
12. Process according to claim 11, wherein the pH in the reactor is adjusted by adding an alkaline agent.
13. Process according to claim 12, wherein said alkaline agent is selected from the group consisting of NH3, KOH, NaOH.
14. Process according to claim 1, wherein during bio-degradation, the mixture in the reactor is maintained at between about 15° and 40°C.
15. Process according to claim 1, wherein during bio-degradation, the mixture in the reactor is maintained at between about 18 and 22°C.
16. Process according to claim 14, wherein the temper-ature in said reactor is maintained at about 20°C.
17. Process according to claim 1, wherein said reactor is maintained under aerobic conditions by maintaining between about 0.2 to 2.1 ppm oxygen therein.
18. Process according to claim 17, wherein the concen-tration of said oxygen in said reactor is about 1.5 ppm.
19. Process according to claim 17, wherein said oxygen is introduced by adding air to the reactor.
20. Process according to claim 19, wherein said air is mechanically introduced.
21. Process according to claim 19, wherein said air is introduced by bubbling.
22. Process according to claim 1, which comprises dis-charging said biomass-containing body from said reactor, de-watering said biomass-containing body, followed by washing and sterilization.
23. Process according to claim 1, wherein said micro-organisms are acclimatized by contacting them with said liquor for a period of time varying between 10 and 20 days.
24. Process according to claim 1, wherein said micro-organisms comprise a mixture of bacteria, yeasts and micro-fungi.
25. Process according to claim 1, wherein hydraulic re-tention time of said liquor in said reactor is about 72 hours.
26. Process for preparing a biomass which comprises:
a) providing a sulfite waste liquor containing about 6 to about 10 weight % solid material including carbohydrates, b) providing a reactor containing a mixture of micro-organisms including bacteria, yeasts and microfungi derived from domestic or municipal sewage, said microorganisms being acclimatized by contacting them with sulfite waste liquor for a period of time varying between about 10 and about 20 days;
c) mixing said liquor with nutrients comprising NH3 and KH2PO4 and the like;
d) introducing sufficient air in said reactor to main-tain between about 0.2 and about 2.1 ppm dissolved oxygen therein, therefore inducing an aerobic condition with said acclimatized microorganisms;
e) controlling foaming in the reactor by means of anti-foaming devices and/or agents;
f) while continuously introducing said air in said reactor, mixing said microorganisms and said sulfite waste liquor at a temperature between about 18° and 22°C for about 72 hours at pH between about 4 and about 7, thereby allowing biodegradation of said liquor by said microorganisms to give a biomass-containing body;
g) discharging said biomass-containing body into a container and separating the biomass therefrom;
h) washing and sterilizing said biomass;
i) drying and grinding said biomass to give an animal feed.
a) providing a sulfite waste liquor containing about 6 to about 10 weight % solid material including carbohydrates, b) providing a reactor containing a mixture of micro-organisms including bacteria, yeasts and microfungi derived from domestic or municipal sewage, said microorganisms being acclimatized by contacting them with sulfite waste liquor for a period of time varying between about 10 and about 20 days;
c) mixing said liquor with nutrients comprising NH3 and KH2PO4 and the like;
d) introducing sufficient air in said reactor to main-tain between about 0.2 and about 2.1 ppm dissolved oxygen therein, therefore inducing an aerobic condition with said acclimatized microorganisms;
e) controlling foaming in the reactor by means of anti-foaming devices and/or agents;
f) while continuously introducing said air in said reactor, mixing said microorganisms and said sulfite waste liquor at a temperature between about 18° and 22°C for about 72 hours at pH between about 4 and about 7, thereby allowing biodegradation of said liquor by said microorganisms to give a biomass-containing body;
g) discharging said biomass-containing body into a container and separating the biomass therefrom;
h) washing and sterilizing said biomass;
i) drying and grinding said biomass to give an animal feed.
27. Process according to claim 1, wherein said refuse fer-mentable materials, said nutrients, fermentation and handling equipment, and atmosphere in which the process is carried out are utilized without providing aseptic conditions thereto.
28. Process according to claim 1, wherein said micro-organisms are provided in said reactor without previous purification and without providing aseptic conditions thereto.
29. A biomass obtained from a liquor containing refuse fermentable materials treated with microorganisms derived from sewage and comprising in weight percent when dried:
water 0.1 - 6 proteins 25 - 50 minerals 0.1 - 5 vitamins 0.001 - 0.04 whenever prepared by the process of claim 22 or its obvious chemical equivalents.
water 0.1 - 6 proteins 25 - 50 minerals 0.1 - 5 vitamins 0.001 - 0.04 whenever prepared by the process of claim 22 or its obvious chemical equivalents.
30. Process according -to claim 22, which comprises the further steps of drying and grinding said biomass-containing body.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA344,852A CA1108920A (en) | 1980-01-31 | 1980-01-31 | Process of preparing a biomass |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA344,852A CA1108920A (en) | 1980-01-31 | 1980-01-31 | Process of preparing a biomass |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1108920A true CA1108920A (en) | 1981-09-15 |
Family
ID=4116154
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA344,852A Expired CA1108920A (en) | 1980-01-31 | 1980-01-31 | Process of preparing a biomass |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1108920A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0482407A2 (en) * | 1990-10-23 | 1992-04-29 | Orgaver Ag | Process for the production of an animal and/or vegetable nutritive substance from organic waste |
-
1980
- 1980-01-31 CA CA344,852A patent/CA1108920A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0482407A2 (en) * | 1990-10-23 | 1992-04-29 | Orgaver Ag | Process for the production of an animal and/or vegetable nutritive substance from organic waste |
| EP0482407A3 (en) * | 1990-10-23 | 1992-11-25 | Erwin Sen. Hunziker | Process for the production of an animal and/or vegetable nutritive substance from organic waste |
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