Claims:WE CLAIM:

1. A process for biogas production, said process comprising steps of:
inoculating waste cell mass with dung of domestic animal; and
subjecting the inoculated waste cell mass to anaerobic digestion to produce biogas.
2. The process as claimed in claim 1, wherein the waste cell mass is selected from a group comprising cell mass of fungi, cell mass of bacteria and cell mass of mammalian cell, or any combination thereof.
3. The process as claimed in claim 1, wherein the waste cell mass is subjected to treatment selected from a group comprising chemical treatment, mechanical treatment and enzymatic treatment, or any combination thereof, prior to the inoculation.
4. The process as claimed in claim 3, wherein the chemical treatment is selected from a group comprising chemical hydrolysis and solvent treatment, or a combination thereof; the mechanical treatment is selected from a group comprising homogenization and cell lysis; and the enzymatic treatment is selected from a group comprising enzymatic hydrolysis.
5. The process as claimed in claim 1, wherein the concentration of the waste cell mass is ranging from about 10% to 99%.
6. The process as claimed in claim 1, wherein the dung of domestic animal is selected from a group comprising dung of cow, dung of buffalo and dung of pig, or any combination thereof; and wherein the dung of the domestic animal comprises methanogenic microorganism.
7. The process as claimed in claim 6, wherein the microorganism used as inoculum is maintained at cell count ranging from about 0.2 billion cfu/mL to 20 billion cfu/mL.
8. The process as claimed in claim 1, wherein the waste cell mass is fed to the digester at the rate of about 0.6 v/v to 1 v/v of the digester per day.
9. The process as claimed in claim 1, wherein the anaerobic digestion is carried out at a pH ranging from about 6.0 to 8.0; the anaerobic digestion is carried out at a temperature ranging from about 15 °C to 65°C; and the anaerobic digestion is carried out for a cycle period ranging from about 0.5 days to 28 days.
10. The process as claimed in claim 1, wherein feeding of the waste cell mass to a digester is continuous or intermittent; wherein after feeding, the waste cell mass is inoculated with the dung of the domestic animal; and wherein the inoculated waste cell mass in the digester is subjected to continuous agitation or intermittent agitation.
11. The process as claimed in claim 1, wherein the process yields biogas ranging from about 50 m3 to 200 m3 per ton of waste cell feed per day.
12. The process as claimed in claim 1, wherein the process increases biogas yield by about 2-fold to 5-fold as compared to the waste cell mass not subjected to the process as claimed in claim 1.
13. The process as claimed in claim 1, wherein methane in the biogas is ranging from about 50% to 80%.
14. The process as claimed in claim 1, wherein obnoxious odour of the waste cell mass is reduced to barely perceptible level during the anaerobic digestion when compared to waste cell mass not subjected to the process as claimed in claim 1.
15. The process as claimed in claim 1, wherein the process reduces Chemical Oxygen Demand (COD) by about 90% to 99%; the process reduces Biological Oxygen Demand (BOD) by about 90% to 99%; and the process reduces Volatile Fatty Acids (VFA) by about 66% to 77%.

Dated this 03rd day of May, 2017

Durgesh Mukharya
IN/PA-1541
Of K&S Partners
Agent for the Applicant(s)
Mob: +91 7349778249

To:
The Controller of Patents,
The Patent Office, at Chennai , Description:TECHNICAL FIELD
The present disclosure relates to a process for biogas production. The process for biogas production described in the disclosure involves inoculating the waste cell mass with dung of domestic animal and subjecting the waste cell mass to anaerobic digestion. The process of the present disclosure produces biogas with an increased methane content. The process provides an efficient method for utilization of the waste cell mass and drastically minimizes the odour that is typically generated by such waste cell mass. In addition, the process of the present disclosure results in organic solids as a rich source of manure for various agricultural purposes, thereby facilitating environment friendly disposal.

BACKGROUND OF THE DISCLOSURE
Considerable literature is available describing slurry reactors for industrial, municipal, agricultural and farm solid waste and/or biomass digestion. The waste, is typically mixed with water or effluent to at least partially suspend the solid particles to be in contact with the microorganisms. However, the source of organic waste that has been described is primarily biomass comprising fibrous plant matter originating from dedicated energy crops and trees, agricultural crops, as well as agricultural crop wastes and residues, wood wastes and residues, while with organic waste, municipal wastes, manure, animal waste, landfill gas, raw sewage sludge from livestock industries, municipal solid waste, manure, household garbage, plant matter such as hey straw, discarded cellulosic packaging materials, food waste from canteens, or municipal refuse (cellulosic products, particularly Kraft paper) treated alone or in combination with raw sewage sludge. It is well known in the art that anaerobic processes have been used as a method of stabilization of the above-mentioned types of waste streams. Regrettably, tons of waste cell mass generated from a typical fermentation industry such as that for manufacturing of various industrial or therapeutic small molecules, enzymes, peptides, amino acids, proteins, mAbs, etc., has not been considered in the scope of such reports or studies. Thus, an effective treatment of industrial cell mass waste to address the odour and waste disposal issues gripping the fermentation industries is necessary.

Further, majority of anaerobic water treatments make use of the principle of “Up flow Anaerobic Sludge Blanket” (UASB), which is fit for use, only for the waste streams that have less solids percentage. Thus, existing anaerobic digestion processes have limitations, in that they are incapable of handling waste feeds with very high solids content of up to 90% w/w, typical of the cell mass wastes from the fermentation industry,
Further, the digestion of waste cell mass poses altogether different challenges as the waste cell mass is also a living microbe or cell line as against a waste nutritious substrate for the digesting microbes. This could be due to the fact that such complex waste streams pose greater challenge of establishing a finer balance between live cells of the waste cell mass and useful microbial population in the digester. Thus, unlike that observed in a typical waste digestion process, the waste cell mass digestion process witnesses a competitive environment between anaerobic microbes and the microbes present in the waste cell mass. Another challenge could be that the dead waste cell mass in fermentation waste is complex waste that may not get degraded easily and may require pre-treatment of the waste cell mass.

In the absence of a practical solution to this problem of efficient waste disposal, the waste cell mass is either incinerated, wherein lots of energy is consumed, or sent for land filling, wherein a huge amount of space is required. However, in either of the cases, waste cell mass emanates foul and obnoxious odour and has a huge societal and environmental impact. In short, an efficient treatment of the tons of waste cell mass generated globally by the fermentation industry is a burning issue that requires an immediate addressing.

SUMMARY OF THE DISCLOSURE
Accordingly, the present disclosure relates to a process for biogas production, said process comprising steps of:
inoculating waste cell mass with dung of domestic animal; and
subjecting the inoculated waste cell mass to anaerobic digestion to produce biogas.
Said process provides enhanced yield of biogas with increased methane content, reduces BOD and COD levels of waste cell mass slurry by about 90-99% and reduces obnoxious odour associated with fermentation waste to barely perceptible levels.

DETAILED DESCRIPTION
As used herein, the phrases ‘waste cell mass’, ‘cell mass slurry’, ‘spent cell mass’ and ‘cell mass’, ‘have been used interchangeably wherein said phrases refer to used cells from fermentation industry or from cell culture industry/biotechnology industry which is involved in production of products including but not limiting to small molecules, enzymes, proteins, peptides, polysaccharides, polymers and mAbs, or combination thereof.

As used herein, terms defining strength of odour such as but not limiting to barely perceptible, slight, moderate, strong, very strong are based on standards identified in the guidelines on odour pollution & its control (2008) by the Central Pollution Control Board (CPCB). Said terms categorize the odour intensity in increasing order of offensiveness from barely perceptible to very strong. In addition, another category, “obnoxious”, has been introduced in the present disclosure, to designate the odour which is most offensive.

The present disclosure relates to a process for biogas production.

In an embodiment, the process for biogas production involves subjecting the waste cell mass to anaerobic digestion.

In an embodiment, the process for biogas production, comprises steps of:
inoculating waste cell mass with dung of domestic animal; and
subjecting the inoculated waste cell mass to anaerobic digestion.

In an embodiment, the anaerobic digestion of waste cell mass during the process of the present disclosure causes production of biogas with increased methane content.
In an embodiment, the process of the present disclosure leads to enhanced biogas production.
In another embodiment, the anaerobic digestion of waste cell mass during the process of the present disclosure causes reduction in odour from obnoxious levels to barely perceptible levels as compared to waste cell mass not subjected to the process of present disclosure.
In an embodiment, in the process of the present disclosure the waste cell mass is the substrate to produce biogas with high methane content.

In an embodiment, the waste cell mass subjected to anaerobic digestion in the process of the present disclosure includes but is not limited to cell mass derived from fermentation, protein production, monoclonal antibody production and cell culture.

In an embodiment, the waste cell mass comprises cell mass of prokaryotes or eukaryotes or both including but not limiting bacteria, yeast, fungi, mammalian cells which are involved in but not limited to fermentation, protein production, production of small molecules, monoclonal antibody production, production of polymers, production of polysaccharides and cell culture.

In a non-limiting embodiment, the waste cell mass is selected from a group comprising Bacillus sp., Escherichia sp., Streptomyces sp., Serratia sp., Pseudomonas sp., Aspergillus sp., Coleophoma sp., Pichia sp., Saccharomyces sp., and Chinese hamster ovary cells or any combination thereof.
In a non-limiting embodiment, the waste cell mass selected from a group comprising Aspergillus oryzae, Coleofoma empetri, Pichia pastoris, Saccharomyces cerevisiae, Bacillus subtilis, E. coli, Streptomyces hygroscopicus and Pseudomonas putida or any combination thereof.
In a non-limiting embodiment, the waste cell mass is selected from a group comprising cell mass slurry waste from a fermenter, cell mass slurry waste from filtration system, spent broth from the whole broth extraction and cell mass from centrifugation or any combination thereof.

In an embodiment, in the process of the present disclosure, the waste cell mass acts as a rich source of proteins, carbohydrates, fats, micronutrient and salts, during anaerobic digestion, which facilitate multiplication of microorganisms involved in anaerobic digestion, derived from the dung of the domestic animal.

In an embodiment, the waste cell mass subjected to anaerobic digestion in the process of the present disclosure comprises total solids in the range of about 1% w/w to 99% w/w.
In another embodiment, the waste cell mass subjected to anaerobic digestion in the process of the present disclosure comprises total solids content of about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95% or about 99%.
In a non-limiting embodiment, the dung of the domestic animal is an inoculum for inoculating the waste cell mass in the process of the present disclosure, wherein the dung of domestic animal includes but is not limited to dung from cow, buffalo, sheep and pig.

In an embodiment, the dung of the domestic animal comprises methanogenic microorganism which is involved in anaerobic digestion of waste cell mass in the process of the present disclosure.

In a non-limiting embodiment, the inoculum comprises microorganism selected from a group comprising Methanobacterium sp., Methanosarcina sp., Methanococcus sp., Methanobrevibacter sp, Methanotrix sp, Bacteroides sp. or any combination thereof.

In a non-limiting embodiment, the inoculum comprises microorganism selected from a group comprising Mb. omelianskii, Mb. formicicum, Methanosarcina barkerii, Methanosarcina acetivorans, Mb. sohngenii, Ms. methanica, Methanobrevibacter thaueri, Methanococcus. mazeior any combination thereof.

In an embodiment, concentration of inoculum is ranging from about 0.1% v/v to 20% v/v of the overall digester volume.

In a further embodiment, the concentration of inoculum is about 0.1% v/v, about 0.2% v/v, about 0.3% v/v, about 0.4% v/v, about 0.5% v/v, about 0.6% v/v, about 0.7% v/v, about 0.8% v/v, about 0.9% v/v, about 1.0% v/v, about 1.5% v/v, about 2.0% v/v, about 2.5% v/v, about 3.0% v/v, about 3.5% v/v, about 4.0% v/v, about 4.5% v/v, about 5.0% v/v, about 5.5% v/v, about 6.0% v/v, about 6.5% v/v, about 7.0% v/v, about 7.5% v/v, about 8.0% v/v, about 8.5% v/v, about 9.0% v/v, about 9.5% v/v about 10.0% v/v about 10.5% v/v, about 11.0% v/v, about 11.5% v/v, about 12.0% v/v about 12.5% v/v, about 13.0% v/v, about 13.5% v/v, about 14.0% v/v, about 14.5% v/v, about 15.0% v/v, about 15.5% v/v, about 16.0% v/v, about 16.5% v/v, about 17.0% v/v, about 17.5% v/v, about 18.0% v/v, about 18.5% v/v, about 19.0% v/v, about 19.5% v/v or about 20.0% v/v.

In an embodiment, the concentration of inoculum in the process of the present disclosure is selected such that the digester is maintained with high concentration of microorganism to facilitate rapid and efficient anaerobic digestion of waste cell mass, thereby producing enhanced biogas with increased methane content.

In an embodiment, the inoculum has cell count ranging from about 0.2 billion cfu/mL to 20 billion cfu/mL.

In a further embodiment, the inoculum has cell count of about 0.2 billion cfu/mL, about 0.3 billion cfu/mL, about 0.4 billion cfu/mL, about 0.5 billion cfu/mL, about 0.5 billion cfu/mL, about 0.6 billion cfu/mL, about 0.7 billion cfu/mL, about 0.8 billion cfu/mL, about 0.9 billion cfu/mL, about 1 billion cfu/mL, about 1.5 billion cfu/mL, about 2.0billion cfu/mL, about 2.5 billion cfu/mL, about 3.0 billion cfu/mL, about 3.5 billion cfu/mL, about 4.0 billion cfu/mL, about 4.5 billion cfu/mL, about 5.0 billion cfu/mL, about 5.5 billion cfu/mL, about 6.5 billion cfu/mL, about 7.0 billion cfu/mL, about 7.5 billion cfu/mL, about 8.0 billion cfu/mL, about 8.5 billion cfu/mL. about 9.0 billion cfu/mL, about 9.5 billion cfu/mL, about 10.0, about 10.5 billion cfu/mL, about 11.0 billion cfu/mL, about 11.5 billion cfu/mL about 12.0 billion cfu/mL, about 12.5 billion cfu/mL, about 13.0 billion cfu/mL, about 13.5 billion cfu/mL, about 14.0 billion cfu/mL, about 14.5 billion cfu/mL, about 15.0 billion cfu/mL, about 15.5 billion cfu/mL, about 16.5 billion cfu/mL, about 17.0 billion cfu/mL, about 17.5 billion cfu/mL, about 18.0 billion cfu/mL, about 18.5 billion cfu/Ml, about 19.0 billion cfu/mL, about 19.5 billion cfu/mL or about 20.0 billion cfu/Ml.

In another embodiment, the dung of the domestic animal comprises mixed culture of microorganism which ensures complete digestion of waste cell mass for production of enhanced biogas with increased methane content during the process of the present disclosure. Further, the dung of the domestic animal, as inoculum, in the process, is chosen in such a way that the mixed culture in the inoculum is capable of maintaining itself indefinitely as long as a fresh supply of cell mass waste is added because the major product of the fermentation are gases, which escape from the medium leaving little, if any, toxic growth inhibiting products.

In a non-limiting embodiment, the anaerobic digestion of the waste cell mass is conducted in a digester selected from a group comprising Upflow Anaerobic Sludge Blanket (UASB) and Continuous stirred tank reactor (CSTR), or a combination thereof.

In an embodiment, during anaerobic digestion, feeding of the waste cell mass to the reactor or digester is continuous feeding or intermittent feeding, or a combination thereof.

In an embodiment, the waste cell mass is fed into the reactor or the digester in a controlled manner, at a rate ranging from about 0.6% v/v to 1% v/v of the reactor or digester per day. This feeding rate of about 0.6v/v to 1v/v maintains high productivity of biogas with high methane content during the process of the present disclosure.

In a further embodiment, the waste cell mass is fed into the reactor or the digester at a rate of about 0.6% v/v, about 0.7% v/v, about 0.8% v/v, about 0.9% v/v or about 1.0% v/v, wherein this feeding rate maintains high productivity of biogas with high methane content during the process of the present disclosure.

In an embodiment, the total solids in the waste cell mass is ranging from about 1% w/w to 99% w/w.

In a further embodiment, the total solids in the waste cell mass is about 1% w/w, 2% w/w, 3% w/w, 4% w/w, 5% w/w, 6% w/w, 7% w/w, 8% w/w, 9% w/w, 10% w/w, about 15% w/w, about 20 % w/w, about 25% w/w, about 30% w/w, about 35% w/w, about 40% w/w, about 45% w/w, about 50% w/w, about 55% w/w, about 60% w/w, about 65% w/w, about 70% w/w, about 75% w/w, about 80% w/w, about 85% w/w, about 90% w/w, about 95% w/w or about 99% w/w.

In an embodiment, in the process of the present disclosure, the anaerobic digestion of waste cell mass is carried out at pH ranging from about 6.0 to 8.0.

In an alternate embodiment, in the process of the present disclosure, the anaerobic digestion of waste cell mass is carried out at pH ranging from about 6.8 to 7.3.

In a further embodiment, in the process of the present disclosure, the anaerobic digestion of waste cell mass is carried out at pH of about 6.0, about 6.2, about 6.4, about 6.6, about 6.8, about 7.0, about 7.2, about 7.4, about 7.6, about 7.8 or about 8.0.

In an embodiment, in the process of the present disclosure, the anaerobic digestion of the waste cell mass is carried out at a temperature ranging from about 15°C to 65°C.

In a further embodiment, in the process of the present disclosure, the anaerobic digestion of the waste cell mass is carried out at a temperature of about 25 °C, about 30 °C, about 35 °C, about 40 °C, about 45 °C, about 50 °C, about 55 °C, about 60 °C or about 65 °C

In an alternate embodiment, in the process of present disclosure, during anaerobic digestion the temperature of the reaction can be controlled by the injection of water or nutrients or combination thereof into the waste cell mass for enhanced production of biogas with high methane content.

In an embodiment, in the process of present disclosure, during the anaerobic digestion, the waste cell mass is subjected to continuous agitation or intermittent agitation in the digester or reactor.

In another embodiment, in the process of present disclosure, the waste cell mass is subjected to anaerobic digestion for a cycle time ranging from about 0.5 days to 28 days.

In an alternate embodiment, in the process of present disclosure, the waste cell mass is subjected to anaerobic digestion for a cycle time ranging from about 0.5 days to 15 days.

In a further embodiment, in the process of present disclosure, the waste cell mass is subjected to anaerobic digestion for a cycle time of about 0.5 day, about 1 day, about 1.5days, about 2.0 days, about 2.5days, about 3.0 days, about 3.5days, about 4.0 days, about 4.5days, about 5.0 days, about 5.5days, about 6.5days, about 7.0 days, about 7.5days, about 8.5days, about 9.0 days, about 9.5days, about 10.0days, about 10.5days, about 11.0 days, about 11.5days, about 12.0 days, about 12.5days, about 13.0 days, about 13.5days, about 14.0 days, about 14.5days, about 15.0 days, about 15.5days, about 16.5days, about 17.0 days, about 17.5days, about 18.0days, about 18.5days, about 19.0 days, about 19.5days, about 20.0days, 21.0 days, about 21.5days, about 22.0 days, about 22.5days, about 23.0 days, about 23.5days, about 24.0 days, about 24.5days, about 25.0 days, about 25.5days, about 26.5days, about 27.0 days, about 27.5days or about 28.0days.

In a non-limiting embodiment, during the process of the present disclosure, the overflow or effluent from the digester is subjected to further digestion in another or multiple digesters sequentially or simultaneously, optionally along with animal dung.

In an embodiment, use of multiple digesters in the process of the present disclosure, facilitate enhancement of digestion capacity and percentage of digestion in terms of reduction in COD or BOD, or both

In another non-limiting embodiment, in the process of the present disclosure, over flow or effluent from the anaerobic digestion is recycled for the purpose of dilution of incoming waste cell mass, wherein the recycling is performed with or without dewatering.

In another embodiment, the recycled effluent comprises liquid, digested solids, or a mixture of liquids and solids.

In another embodiment, effluent from the digester is treated to recover digested solids and subject liquid for further treatment.

In a non-limiting embodiment, the effluent is subjected to dewatering to obtain semi dried sludge or completely dried solids.

In another non-limiting embodiment, the effluent is treated by a process selected from a group comprising dead end filtration, tangential filtration and centrifugation or any combination thereof.

In an exemplary embodiment, the effluent is treated by dead end filtration using micron filter membranes of porosity ranging from about 0.5 micron to 200 microns, preferably ranging from about 10 microns to 75 microns.

In another exemplary embodiment, the effluent is treated by tangential filtration using hollow fibre microfiltration modules.

In another exemplary embodiment, supernatant from centrifugation of effluent can be treated further for aerobic digestion.

In a non-limiting embodiment, treatment of effluent allows recovery of digested solids in the range of about 90% to 99%.

In a further embodiment, the treatment of effluent allows recovery of digested solids of about 90%, about 91%, about 92%, about 93%, about 94%, about 95% about 96%, about 97%, about 98% or about 99%.

In an embodiment, concentrate obtained after treatment of effluent is subjected to further treatment selected from a group comprising belt filter press, screw press, plate and frame press filter, rotary vacuum filter, agitated nutsche filters and centrifuge or any combination thereof, to recover dewatered digested solids.

In an alternate embodiment, the concentrate obtained after treatment of effluent is directly dried using Agitated Thin Film Dryer (ATFD) or Multiple Effect Evaporator (MEE) followed by thin film dryer, spray dryer, rotary vacuum dryer, sun drying or any combination thereof.

In an embodiment, the effluent from the digester and the solids recovered from therein are not foul smelling and can be utilized as agricultural fertilizer.

In an embodiment, the recovered solids comprise Carbon in the range of about 30% to 60%, Nitrogen in the range of about 7% to 12%, Potassium in the range of about 2% to 3%, Phosphorous in the range of about 1% to 3%, Sulphur in the range of about 0.5% to 1.0% and Magnesium in the range of about 0.5% to 1.0%

In a further embodiment, the absence of foul smell of the effluent is due to microbial degradation of odour producing compounds in the waste cell mass.

In an embodiment, the process of the present disclosure reduces obnoxious odour of the waste cell mass to barely perceptible levels during the anaerobic digestion when compared to waste cell mass not subjected to the process of the present disclosure.

In an embodiment, the process of the present disclosure causes efficient generation of biogas with increased methane content, which is achieved by maintaining high population of useful microbes from the dung of domestic animal, using optimum feeding of incoming waste cell mass slurry and optimum removal of the effluent from the digester.

In a non-limiting embodiment, the process of the present disclosure reduces the Chemical Oxygen Demand (COD) by about 90% to 99%.

In a further embodiment, the process of the present disclosure reduces the Chemical Oxygen Demand (COD) by about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97% about 98% or about 99%.

In another non-limiting embodiment, the process of the present disclosure reduces Biological Oxygen Demand (BOD) by about 90% to 99%.

In a further embodiment, the process of the present disclosure reduces the Biological Oxygen Demand (BOD) by about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98% or about 99%.
In an embodiment, the process of the present disclosure reduces Volatile Fatty Acids (VFA) concentration by about 66% to 77%
In a further embodiment, the process of the present disclosure reduces Volatile Fatty Acids (VFA) concentration by about 66%, about 67%, about 68%, about 69%, about 70%, about 71%, about 72%, about 73%, about 74%, about 75%, about 76% or about 77%.
In a non-limiting embodiment, the process of the present disclosure maintains Volatile Fatty Acids (VFA) concentration lower than 10 g/L in the effluent by optimum feeding and withdrawal.

In another non-limiting embodiment, the process of the present disclosure produces biogas with increased methane percentage ranging from about 50% to 80%, depending upon the cell-mass type used as feed in the digester.
In a further embodiment, the process of the present disclosure produces biogas with increased methane percentage of about 50%, about 55%, about 60%, about 65%, about 70%, about 75% or about 80%.
In a further embodiment, the biogas produced is subjected to a suitable process including but is not limited to scrubbing to remove other gases selected from a group comprising carbon monoxide and hydrogen sulphide or a combination thereof, before the remaining gas, methane is transported to storage or to combustion.

In an embodiment, the process of the present disclosure results in a biogas yield of about 50 m3 to 100 m3 per ton of waste cell mass per day.

In a further embodiment, the process of the present disclosure results in a biogas yield of about 50 m3 per ton of waste cell mass per day, about 55 m3 per ton of waste cell mass per day, about 60 m3 per ton of waste cell mass per day, about 65 m3 per ton of waste cell mass per day, about 70 m3 per ton of waste cell mass per day, about 75 m3 per ton of waste cell mass per day, about 80 m3 per ton of waste cell mass per day, about 85 m3 per ton of waste cell mass per day, about 90 m3 per ton of waste cell mass per day, about 95 m3 or about 100 m3 per ton of waste cell mass per day.
In an alternate embodiment, the process of the present disclosure results in a biogas yield ranging from about 150 m3 to 200 m3 per ton of waste cell mass per day by subjecting the waste cell mass to treatment selected from a group comprising chemical treatment, mechanical treatment and enzymatic treatment, or any combination thereof, before initiating the anaerobic digestion.

In a further embodiment, the process of the present disclosure results in a biogas yield of about 150 m3 per ton of waste cell mass per day, about 160 m3 per ton of waste cell mass per day, about 170 m3 per ton of waste cell mass per day, about 180 m3 per ton of waste cell mass per day, about 190 m3 per ton of waste cell mass per day or about 200 m3 per ton of waste cell mass per day by subjecting the waste cell mass to treatment selected from a group comprising chemical treatment, mechanical treatment and enzymatic treatment, before initiating the anaerobic digestion.

In another embodiment, the process of the present disclosure result in biogas yield of about 50m3 to 200m3 per ton of waste cell mass per day.

In a further embodiment, the process of the present disclosure result in biogas yield of about 50 m3 per ton of waste cell mass per day, about 55 m3 per ton of waste cell mass per day, about 60 m3 per ton of waste cell mass per day, about 65 m3 per ton of waste cell mass per day, about 70 m3 per ton of waste cell mass per day, about 75 m3 per ton of waste cell mass per day, about 80 m3 per ton of waste cell mass per day, about 85 m3 per ton of waste cell mass per day, about 90 m3 per ton of waste cell mass per day, about 95 m3, about 100 m3 per ton of waste cell mass per day, about 110 m3 per ton of waste cell mass per day, about 120 m3 per ton of waste cell mass per day, about 130 m3 per ton of waste cell mass per day, about 140 m3 per ton of waste cell mass per day, about 150 m3 per ton of waste cell mass per day, about 160 m3 per ton of waste cell mass per day, about 170 m3 per ton of waste cell mass per day, about 180 m3 per ton of waste cell mass per day, about 190 m3 per ton of waste cell mass per day or about 200 m3 per ton of waste cell mass per day.

In an embodiment, the process of the present disclosure increases biogas yield by about 2-fold to 5-fold as compared to waste cell mass not subjected to the process of the present disclosure.

In a further embodiment, the process of the present disclosure increases biogas yield by about 2-fold, about 2.5-fold, about 3-fold, about 3.5-fold, about 4- fold, about 4.5-fold or about 5-fold as compared to waste cell mass not subjected to the process of present disclosure.

In an alternate embodiment, the process of the present disclosure increases biogas yield by about 2-fold to 2.9-fold fold, when the waste cell mass is not subjected to treatment selected from a group comprising chemical treatment, mechanical treatment and enzymatic treatment, as compared to the waste cell mass not subjected to process of the present disclosure.

In another alternate embodiment, the process of the present disclosure increases biogas yield by about 3.8 fold to 5 fold, by subjecting the waste cell mass to treatment selected from a group comprising chemical treatment, mechanical treatment and enzymatic treatment, as compared to the waste cell mass not subjected to process of the present disclosure.

In a non-limiting embodiment, the chemical treatment is selected from a group comprising solvent treatment, such as treatment with alcohol, ester, acid and base or a combination thereof.

In a non-limiting embodiment, the mechanical treatment is selected from a group comprising mechanical homogenization, sonication, trituration or any combination thereof.

In a non-limiting embodiment, the enzymatic treatment is selected from a group comprising enzymatic hydrolysis, by employing enzymes such as but not limiting to protease, amylase, beta glucanase, xylanase and cellulase or any combination thereof.

In another non-limiting embodiment, the biogas generated is collected and used in applications selected from a group comprising power generation, boiler fuel, cooking gas or any combination thereof.

In an embodiment, the present disclosure further relates to a system for the process for biogas production wherein said system comprises digester, gas clean-up zone and effluent collection zone.

In an embodiment, in the system, the inlet of the digester receives the waste cell mass and the inoculum, agitator in the digester keeps the said waste cell mass stirring; the digester is fluidly connected to the gas clean-up zone, which receives the biogas generated during anaerobic digestion of the waste cell mass. Alternately, the digester is fluidly connected to another digester or effluent collection zone, which receives the effluent or the overflow from the digester.

In an embodiment, the system comprises at least one digester.

In another embodiment, the gas clean-up zone comprises processes for clean-up of the biogas, including but is not limiting to gas scrubbing for removal of gases such as hydrogen sulphide (H2S).

In a further embodiment, the system comprises multiple digesters, wherein said multiple digesters are connected in series or in parallel, or a combination thereof.

In an embodiment, an objective of this invention is to improve methane or pipeline gas production under treatment conditions which assure high chemical oxygen demand (COD) as well as biochemical oxygen demand (BOD) removal from the waste cell mass.

In a further embodiment, another objective of the present invention is to collect increased amounts of methane gas from anaerobic digestion of organic wastes under improved conditions of stabilizing waste products so that problems of disposing of liquid and solid effluents from fermentation industry are reduced or eliminated.

In a still further embodiment, another objective of the present invention is to optionally separate an acid-forming phase from a methane-forming phase so that each phase can be operated independently to attain associated advantages in the overall anaerobic digestive process for producing methane gas and stabilizing the cell mass waste.

In an embodiment, the present disclosure further describes the advantages associated with the process of anaerobic digestion of waste cell mass, such as:
1. Production of biogas with increased methane content (about 50% to 80%) and high heating value from essentially waste cell mass.
2. The process is less energy demanding, self-reliant and economical.
3. Use of only waste cell mass as substrate for the anaerobic digestion does not cause any toxicity to the digesting microbes (from the inoculum) even after run time of 3 weeks.
4. Better methane production yields and rates are obtained due to optimization of the contact time between the methane forming micro-organisms and the waste cell mass feed.
5. Reduction in COD and BOD is consistent in the range of about 90% to 99% even after run time of 3 weeks.
6. Reduction in the % solids, VFA content, BOD and COD in the feed waste slurry of about 90% to 99%, in the processed waste stream.

In an embodiment, the anaerobic digestion defined in the process of the present disclosure is applicable to all type of waste cell mass including but not limited to cell mass derived from fermentation, protein production, monoclonal antibody production and cell culture, for enhanced production of biogas, reduction of BOD and COD by about 90% to 99%, and reduction of obnoxious odour to barely perceptible level.

In a further embodiment, providing working examples for all type of waste cell mass derived from fermentation, protein production, monoclonal antibody production and cell culture is considered redundant.

EXAMPLES
EXAMPLE 1:
Anaerobic digestion of waste cell mass in the presence of inoculum for production of biogas
About 25 kg of the waste cell mass with about 40% w/w solids (Aspergillus oryzae cell mass), is added in order to keep the overall batch size at about 45 Kg is added to the pre-sterilized 50 L Nalgene container. About 1.0 kg of the inoculum (cow dung, buffalo dung, pig dung) is added to the container. The overall slurry (inoculum and waste cell mass) is mixed well using an overhead stirrer and appropriately diluted with fresh water to have total solids at about 20% w/w.

The solids are determined by spinning a small sample at about 10,000 rpm for about 10 minutes and noting the percentage of weight of the settled pellet as against total weight of sample taken. The Nalgene container is tightly closed with a cap. The cap has nozzles to vent out gas as well as to add waste feed to the bottom of container using a dip line and/or withdraw effluent from the top of the container using a nozzle at the top.

The vent or the exhaust is connected to a tube that will swell up due to the gas that will get collected in it. The container is kept for incubation at ambient temperature between 25° C and 40 ° C outside the building. The exhaust or the vent is closed during the incubation period of about 0.5 day to 28 days. The broth is kept at static conditions during the incubation period. The tube, once filled completely, is connected to a stove. The stove is switched on using a regulator and the flame is observed till it continues to last. The duration for which the flame lasted, is noted down. After the gas is burnt, the tube is reconnected to the exhaust line of the container in order to refill the tube with the gas that is being further produced. This is continued till the tube is getting filled.

Results of said flame test qualitatively indicate the volume and quality of gas produced. The comparison between different inoculum is shown below:

Table 1: Flame test, demonstrating the effect of biogas with increase methane content, generated by the process of the present disclosure.
Sl. No. Inoculum Duration for which flame lasted (minutes) Remarks
1st day 2nd day 3rd day 4th day 5th day 6th day 7th day 8th day 9th day 10th day 11th day 12th day 13th day 14th day 15th day
1 Cow dung 35 37 36 35 36 35 36 35 33 32 30 28 20 15 10 Dark blue flame
2 Buffaloes dung 32 33 33 34 35 34 35 34 33 31 30 29 18 14 10 Dark blue flame
3 Pig Dung 33 34 33 33 34 33 34 31 30 30 27 24 18 15 9 Dark blue flame

The results of this example suggest that the waste cell mass is effectively digested (anaerobic) in the presence of inoculum, such as cow dung, buffalo dung and pig dung, respectively, by the process of the instant disclosure, to produce biogas with increased methane content, which was consistent for period of about 8 days to 10 days (as demonstrated by the flame test in Table 1).

EXAMPLE 2:
Anaerobic digestion of various waste cell mass for production of biogas
About 1 kg of the inoculum (cow dung) is mixed with about 25kg of waste cell mass (Aspergillus oryzae, Coleofoma empetri, Pichia pastoris, Saccharomyces cerevisiae, Bacillus subtilis, E. coli, Streptomyces hygroscopicus, Pseudomonas putida or Chinese hamster ovary (CHO) cell line and combination thereof). The experimental conditions in this example are similar to those described in example 1. The results are shown in the table below:

Table 2: Flame test, demonstrating the effect of biogas with increase methane content, generated by the process of the present disclosure from various waste cell mass, individually and in combination.

Sl. No Type of waste cell mass Duration in minutes for which flame lasted Remarks
1st day 2nd day 3rd day 4th day 5th day 6th day 7th day 8th day 9th day 10th day 11th day 12th day 13th day 14th day 15th day
1 Aspergillus Oryzae 35 37 36 35 36 35 36 35 33 32 30 28 20 15 10 Dark blue flame
2 Coleofoma empetri 34 37 35 36 36 35 35 34 34 32 31 30 21 16 11 Dark blue flame
3 Pichia pastoris 34 36 36 35 35 34 35 35 32 29 27 23 17 13 8 Dark blue flame
4 Saccharomyces cerevisiae 33 34 33 33 34 33 31 32 30 29 26 23 19 14 9 Dark blue flame
5 Bacillus subtilis 32 33 32 32 33 33 32 31 31 30 26 22 17 13 7 Dark blue flame
6 E.coli 33 32 32 32 34 33 32 30 30 29 27 24 19 16 10 Dark blue flame
7 Streptomyces hygroscopicus 32 32 32 32 34 34 32 31 30 30 27 25 20 17 11 Dark blue flame
8 Pseudomonas putida 33 33 33 33 31 30 30 30 29 28 24 23 20 17 13 Dark blue flame
9 Chinese hamster ovary cell line 30 31 32 33 33 33 30 30 28 25 23 20 18 17 11 Dark blue flame
10 All Mixed 32 32 34 35 36 36 34 35 33 32 28 24 19 17 12 Dark blue flame

Due to the process of the present disclosure even if the source of the waste cell mass is very diverse (prokaryotic or eukaryotic), the amount of biogas produced is similar during the anaerobic digestion of the waste cell mass.
EXAMPLE 3:
Percentage of methane in the biogas produced using pre-treated waste cell mass in the process of the present disclosure
In an experimental set-up similar to the one described in example 1, the waste cell mass is processed before adding to the anaerobic digester. The waste cell mass is processed using different chemicals or reagents, such as

• about 1% to 10% of w/w butanol, ethyl acetate and ethanol, respectively.
• by adding acid such as orthophosphoric acid (pH 1.0) and alkali such as sodium hydroxide (pH 14.0) to vary pH in the acidic as well as basic ranges.
• the waste cell mass is treated with a mixture of hydrolyzing enzymes such as protease, amylases, beta glucanases and cellulases
The quality and volume of biogas produced is described in the Table 3:

Table 3: illustrates the volume and the quality of the biogas generated.
Sl. No. Type of treatment Results at the end of 7th Day
volume Duration for gas burning Methane CO2 Other gases Remarks
(L) (minutes) (% v/v) (%v/v) (%v/v)
1 W/o treatment 55 37 70.81 26.33 2.86 Blue flame
2 Mixed with 1% butanol 63 50 68.11 29.01 2.88 Blue flame
3 Mixed with 10% butanol 68 125 62.34 34.89 2.77 Blue flame
4 Mixed with 1% ethyl acetate 65 52 70.11 26.80 3.09 Blue flame
5 Mixed with 10% ethyl acetate 70 133 61.99 34.55 3.46 Blue flame
6 Mixed with 1% alcohol 60 48 67.22 30.21 2.57 Blue flame
7 Mixed with 10% alcohol 66 126 60.12 36.75 3.13 Blue flame
8 pH adjusted to 1.0 with OPA 35 39 79.21 18.01 2.78 Blue flame
8 pH adjusted to 14.0 with caustic 45 44 77.35 18.77 3.88 Blue flame
9 Treated with a mixture of protease, amylase, cellulases and glucanases 60 40 81.09 16.45 2.46 Blue flame
10 Homogenized with a high speed homogenizer 62 40 75.41 22.14 2.45 Blue flame

Thus, irrespective of the treatment done, the waste cell mass subjected to the process of the present disclosure produces biogas with not less than 60% v/v methane.

EXAMPLE 4:
Effect of varying the amount of waste cell mass and total solids percentage in the digester during anaerobic digestion in the process of present disclosure.
A viscous waste (waste cell mass) with about 75% w/w solids containing primarily Aspergillus species is used as a starting material for this experiment. The addition of feed (waste cell mass) into the digester is done at different concentrations in such a way that the total solids concentration (by spin test) varies from 10% to about 50% v/v at the time of addition and the gas production rate recorded for up to 16 days. The experimental condition is similar to the one described in example 1. The waste cell mass and inoculum in the digester is mixed intermittently. The volume of gas is measured by collecting the gas in an inverted measuring cylinder that has been placed in a beaker full of water. The table below shows results:

Table 4: illustrates, the volume of biogas at different total solid concentration of waste cell mass.
S.No. % v/v total solids concentration Volume of gas produced (L/day) on different days
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1 2 (Control) 12.8 9.6 17.28 10.56 19.84 14.4 11.2 12.16 7.68 6 6.4 5.12 4.48 3.84 4.16 3.2
2 10 35.2 32 67.2 60.8 46.4 24 17.4 17.28 8.96 9.28 8 6.4 6.72 6.4 7.04 6.4
3 20 52.8 54.4 86.4 84.8 70.4 40 25.6 25.6 12.8 12.4 12 9.74 9.6 9.44 9.6 9.28
4 30 60.8 62.4 94.4 99.2 91.2 54.4 41.6 35.2 25.6 19.2 16 14.4 14.7 14 14.4 14.7
5 40 60.8 64 90 96 88 70.4 76.8 65.6 56 46.4 36.8 25.6 20.8 20 19.2 16
6 50 54.4 56 59.2 62.4 78.4 94.4 99.2 96.0 91.2 72 51.2 40 35.2 32 27.2 20.8

The results show that the anaerobic digestion can be achieved irrespective of the concentration of waste feed added to the digester. Particularly, increase in solid concentration of waste cell mass between 30% and 50% results in higher biogas productivity as illustrated in Table 4.

EXAMPLE 5:
Characterization and comparison of the waste feed (waste cell mass) and the outflow stream from the digester
The mixed waste cell mass (untreated and solvent treated) with about 40% solids w/w, as well as the withdrawal from the anaerobic digester are analysed for the content of Volatile Fatty Acids (VFA), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD) as well as Total Solids. The results are shown in Table 5 below.

Table 5: illustrates the characteristic of undigested waste cell mass (treated and untreated) and digested waste cell mass (treated and untreated)
Sl. No. Parameter Mixed waste cell mass Feed Solvent treated Mixed waste cell mas feed Mixed waste cell mass slurry post digestion Solvent treated mixed waste cell mass post digestion
1 Total solids by spin test (%) 45.24 44.45 11.00 9.80
1 Total solids by LOD (%) 12.52 10.65 2.35 2.18
2 Total volatile solids (%) 10.40 8.61 1.50 1.48
3 VFA (%) 0.250 0.265 0.11 0.09
4 COD (%) 17.90 40.50 2.45 2.25
5 BOD 27oC; 3 days (%) 7.85 19.35 0.65 0.40
6 Total organic carbon (%) 4.35 9.78 0.62 0.56
7 Total kjeldhal nitrogen (%) 1.10 0.90 0.24 0.22

It is observed that the Total Solids, BOD, COD and VFA are significantly reduced post digestion as compared to the levels measured in the waste cell mass feed without digestion.

EXAMPLE 6:
Counts as well as nutrient value of the processed waste (liquid as well as solid).
In another experiment, the counts of the bacteria in the inoculum are varied and the impact of the same on anaerobic digestion is observed in the process of production of biogas of the present disclosure.

Table 6: illustrates the volume of gas produced when cell count is maintained at about 0.2 to 2 billion cfu/mL
Sl. No. % v/v waste addition Volume of gas produced (L/day)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1 Nil (Control) 6.8 6.6 10.28 7.50 12.50 9.4 7.2 8.16 5.68 4.55 3.4 2.8 2.48 1.84 1.46 1.2
2 20% v/v 30.8 41.2 56.8 64.2 45.4 30 20.6 19.6 10.8 8.4 8.1 6.79 6.3 6.0 5.6 6.30

Table 7: illustrates the volume of gas produced when cell count is maintained at > 2 billion cfu/mL
Sl. No. % v/v waste addition Volume of gas produced ( L/day)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1 Nil (Control) 12.8 9.6 17.28 10.56 19.84 14.4 11.2 12.16 7.68 6 6.4 5.12 4.48 3.84 4.16 3.2
2 20% v/v 52.8 54.4 86.4 84.8 70.4 40 25.6 25.6 12.8 12.4 12 9.74 9.6 9.44 9.6 9.28

It is observed that maintaining higher counts i.e. >2 b cfu/mL can help in aiding the digestion and also producing the biogas faster.

EXAMPLE 7:
Biogas production using a continuous or intermittent fed batch or batch mode of operation
The rate of biogas production is analysed by varying the feed of waste cell mass (mixed waste comprising of Aspergillus oryzae, Bacillus subtilis and Pichia pastoris) slurry intermittently as well as in a continuous mode. The experimental set up is similar to the one described under example 1. The overall content of solids is 40% in the slurry (waste cell mass). The slurry is fed in a continuous as well as intermittent feeding mode with rates varying from nil to as high as 1.0% v/v/day. The results are shown in the table below:

Table 8: illustrates the volume of biogas produced by continuous and intermittent feeding at different feeding rates
Sl. No. Experimental Detail Volume of gas produced (L)
Day 7th Day 8th Day 10th Day 12th Day 14th Day 16th Day 18th Day 20th Day 22th Day 24th Day 26th Day 28th Day 30th
1 No Feeding 12.8 13.6 17.28 15.56 19.84 14.4 11.2 12.16 7.68 6.1 6.4 5.12 4.48
2 0.1% v/v/day continuous 13.1 13.8 17.8 15.6 20.4 14.8 12.1 12.60 7.80 6.25 6.6 5.20 4.55
3 0.2% v/v/day continuous 13.4 14.5 18.2 15.8 20.8 14.9 12.3 12.80 8.10 6.5 6.85 5.50 4.80
4 0.4% v/v/day continuous 13.8 14.6 18.7 16.3 20.9 15.1 13.2 13.10 8.25 6.6 6.9 5.60 4.90
5 0.6% v/v/day continuous 14.1 15.2 18.9 16.5 21.4 15.4 13.5 13.50 8.48 6.85 7.10 5.70 5.20
6 0.8% v/v/day continuous 14.5 15.6 19.2 17.0 20.2 15.8 13.8 13.60 8.65 7.0 7.4 5.90 5.40
7 1.0% v/v/day continuous 14.1 15.1 18.55 16.5 16.9 15.2 13.9 14.0 8.68 7.1 7.45 6.10 4.48
8 0.1% v/v/day intermittent 13.1 13.50 17.5 15.55 20.35 14.5 12.3 12.40 7.70 6.35 6.65 5.30 4.50
9 0.2% v/v/day intermittent 13.3 14.10 18.3 15.65 20.65 14.8 12.2 12.90 8.00 6.45 6.75 5.60 4.85
10 0.4% v/v/day intermittent 13.5 14.60 18.5 16.25 20.85 15.3 13.5 13.20 8.35 6.56 6.95 5.70 4.80
11 0.6% v/v/day intermittent 14.2 15.20 18.6 16.55 21.75 15.5 13.8 13.55 8.68 6.80 7.15 5.80 5.10

Biogas production is achieved with continuous feeding as well as intermittent feeding. The amount of biogas produced is similar at varying quantities of waste cell mass feed (0.1 to 1% v/v/day), although it is optimal at 0.5% to 0.8% v/v/day.

EXAMPLE 8:
Multiple anaerobic digestion in series in the process of production of biogas.
The effluent from one digester is collected and added to another similar digester with an aim to further digest the material. The experimental step-up is similar to the one followed under example 1.

Table 9: illustrates the analysis of digestate post digestion of feed in a single digester and multiple digesters in series
Sl. No. Parameter Feed for 1st digester Effluent from 1st digester Effluent from 2nd digester Remarks
1 % solids w/w 40 6 4 Value in the whole effluent as such (i.e., solids + liquid together)
2 COD (ppm) 175000 23800 600
3 BOD (ppm) 75800 6000 250
4 VFA (%) 0.255 0.11 0.05
5 Odour Pungent / foul Negligible Negligible

The results show that in order to achieve complete digestion of solids, multiple digesters can be used in series.

EXAMPLE 9:
Anaerobic digestion of treated and untreated cell mass during the process of biogas production
The amount of biogas produced from unit weight of cell mass per day is evaluated for the following samples - dung alone (dung control), 10% ethyl acetate treated with dung (solvent control), waste cell mass digested with dung and waste cell mass treated with 10% ethyl acetate and digested with dung. The results along with the fold difference to the dung control are tabulated below.

Table 10: Illustrates the quantity of biogas produced in cubic meter per ton of waste cell mass per day
Treatment Condition Day 4 Day 7 Day 14 Day 21
Biogas m3/ton Fold difference Biogas m3/ton Fold difference Biogas m3/ton Fold difference Biogas m3/ton Fold difference
Dung control 15 1.0 28 1.0 42.5 1.0 48.9 1.0
Solvent control 14 0.9 28 1.0 42 1.0 48 1.0
Untreated cell mass under digestion 43 2.9 58 2.1 60 1.4 65 1.3
Treated cell mass under digestion 57 3.8 143 5.1 169 4.0 175 3.6

The results show that there is about 5-fold difference in biogas production when waste cell mass is subjected to the anaerobic digestion post treatment in the process of the present disclosure in comparison to dung alone condition.

EXAMPLE 10:
Reduction of odour in waste cell mass during anaerobic digestion in the process of present disclosure
Effect of anaerobic digestion of waste cell mass on odour is evaluated daily on the following samples over a period of 1 week. The dung alone or waste cell mass alone or waste cell mass treated with 10% w/w ethyl acetate samples are left out in the open for 1 week whereas the digested cell mass (untreated and treated) are subjected to anaerobic digestion by the process of the present disclosure in the digester for about 1 week. The odour intensity from each sample is evaluated based on the guidelines on odour pollution & its control (2008) released by Central Pollution Control Board (CPCB)and the results are tabulated below.
Table 11: Illustrates the odour intensity pre- and post-digestion of waste cell mass.
Treatment Condition Qualitative odour
1st day 2nd day 3rd day 4th day 5th day 6th day 7th day
Dung only Moderate Slight Slight Slight Barely perceptible Barely perceptible Barely perceptible
Waste cell mass alone Moderate Strong Very strong Obnoxious Obnoxious Obnoxious Obnoxious
Treated waste cell mass only Moderate Moderate Strong Strong Very strong Obnoxious Obnoxious
Dung + Waste cell mass Moderate Moderate Slight Slight Barely perceptible Barely perceptible Barely perceptible
Dung + Treated waste cell mass Moderate Slight Slight Barely perceptible Barely perceptible Barely perceptible Barely perceptible

These results indicate that anaerobic digestion of waste cell mass results in considerable reduction of odour to barely perceptible levels in comparison to obnoxious levels observed for undigested waste cell mass.

EXAMPLE 11:
Use of digested solid waste from anaerobic digestion of waste cell mass from the process of the present disclosure

The solids recovered after the process of the present disclosure are used for landfilling directly, as nutrient or manure for various agricultural purposes. The Table 12 below shows the composition of the recovered solid post anaerobic digestion and is similar in composition to the manure used for agriculture.

Table 12: Illustrates the content in the solid waste obtained from the anaerobic digestion of waste cell mass.

Component Percentage
Carbon 30-60
Nitrogen 7-12
Potassium 2-3
Phosphorous 1-3
Sulphur 0.5-1.0
Magnesium 0.5-1.0

Likewise, the biogas generated is collected and used for various end applications, such as power generation, boiler fuel and cooking gas.