ANAEROBIC PROCESS FOR PRODUCTION OF METHANE RICH BIOGAS

Abstract

The present invention relates to an integrated method for methane rich biogas production from anaerobe systems using multiple reactors and various types of on-site selective enriched microbial consortium production. Biomass/organic waste is converted to biogas rich in methane content and minimum or absence of hydrogen sulphide content at reduced hydraulic retention time (HRT). More particularly, the present invention relates to an on-site enrichment of selective microbe with specified biochemical function and its dosage into the respective digester at regular time intervals which improve the biomass conversion through biochemical steps, resulting into maximum production of methane rich biogas in a self-controlled biochemical function inside each bioreactor in a comparatively lesser time intervals.

Claims

1. A process for methane rich biogas production from organic wastes in a biogas production bioreactor, the process comprising: a) preparing an organic waste feed by subjecting the organic waste feed to a size reduction of 1-5 mm, by cutting, shredding, or pulverization; b) pretreating the organic waste feed of reduced size by hydrothermal treatment, extrusion, ozonation, hydrodynamic cavitation, or a combination thereof; c) mixing the organic waste feed with water to prepare a feed slurry having 25-50% of total solid (TS) (w/w); d) transferring the feed slurry through a series of reactors to produce biogas, wherein each reactor is attached with an on-site selective bioinoculant generation reactor, wherein the bioinoculant generation reactor is of 1/500.sup.th size of the biogas production bioreactor; wherein on-site selective bioinoculant generation reactor is configured to provide an on-site selective microbial consortium, and e) removing H.sub.2S and CO.sub.2 in-situ from the biogas.

2. The process, as claimed in claim 1, wherein the organic waste feed is subjected to a pretreatment process, when lignin content is more than 10% of the total organic waste.

3. The process as claimed in claim 1, wherein the series of reactors comprises reactors R1, R2, R4, R6, and R8 connected in series for processing the feed slurry, and wherein the reactors R2, R4, R6, and R8 are connected to reactors R3, R5, R7, and R9, respectively, for providing a blend of microbes.

4. The process as claimed in claim 3, wherein the feed slurry in reactors R2, R4, R6, and R8 is adjusted to a total solid (TS) percent of 8-12% (w/w) by addition of water.

5. The process as claimed in claim 3, wherein 80% of a content of the reactors R3, R5, R7, and R9 is transferred to R2, R4, R6, and R8, respectively, at an interval 24 hours, and wherein the volume of R3, R5, R7, and R9 is restored using a combined slurry from the reactors R2, R4, R6, and R8, respectively, and nutrient rich waste or wastewater, wherein the nutrient rich waste comprises molasses, spent wash, and fruit waste.

6. The process, as claimed in claim 3, wherein the feed slurry in the reactor R1 is maintained at a temperature in a range of 70-90° C. with intermittent mixing for 5-24 hours.

7. The process as claimed in claim 3, wherein the feed slurry in the reactors R2, R4, and R6, is maintained at a temperature in a range of 30-50° C. with intermittent mixing for 48-72 hours.

8. The process as claimed in claim 3, wherein the feed slurry in the reactor R8 is further supplied with 0.01-0.05% FeCl.sub.3 and the reactor R8 is maintained at a temperature in a range of 30-50° C. with intermittent mixing for 72-144 hours.

9. The process as claimed in claim 3, wherein the biogas is collected from the reactors R6 and R8, wherein the biogas is rich in methane and has reduced concentration of H.sub.2S.

10. The process as claimed in claim 3, wherein the blend of microbes grown in reactors R3 and R5 is supplied to the reactors R2 and R4, respectively in an initial concentration of 10.sup.4-10.sup.5 CFU/g of the feed slurry, and wherein the blend of microbes comprises hydrolytic acidogenic, acetogenic and methanogenic microbes.

11. The process as claimed in claim 3, wherein the blend of microbes grown in reactors R7 and R9 is supplied to reactors R6 and R8, respectively in the initial concentration of 10.sup.6 to 10.sup.12 CFU/g of the feed slurry, and wherein the blend of microbes comprises hydrolytic acidogenic, acetogenic, methanogenic, and sulfide oxidizing microbes.

12. The process as claimed in claim 3, wherein the reactors R6 and R8 are further supplied with a blend of microbes comprising hydrogen producing microbes from the reactor R10, and wherein the ratio of the blend of microbes supplied from the reactors R7 and R10 to the reactor R6 and from the reactors R9 and R10 to the reactor R8 is in a ratio of 2:1, and wherein the reactor R10 is maintained at a temperature in a range of 60-70° C. and a volume of the reactor R10 is restored by a combination of the feed slurry from the reactor R8 and a nutrient rich waste or, wastewater, wherein the nutrient rich waste comprises molasses, spent wash, and fruit waste.

13. The process as claimed in claim 10, wherein the blend of microbes comprising hydrolytic acidogenic, acetogenic and methanogenic microbes is selected from the group consisting of Desulfovibrio sp. (MTCC No. 25301), Brevibacterium sp. (MTCC 25254), Methanothermobacter sp. (MTCC No. 25268), Methanolobus sp. (MTCC No. 25302), Thermotoga sp. (MTCC No. 25304), Methanosarcina sp. (MTCC No. 25300), Clostridium sp. (MTCC No. 25264), Methanobacterium sp. (MTCC No. 25266) and Lactobacillus sp. (MTCC No. 25282), Moorella sp. (MTCC No. 25267) and, Methanosaeta sp. (MTCC No. 25303), Pyrococcus sp. (MTCC No. 25305) and Shewanella sp. (MTCC No. 25020).

14. The process as claimed in claim 11, wherein the blend of microbes comprising hydrolytic acidogenic, acetogenic and methanogenic microbes is selected from the group consisting of Desulfovibrio sp. (MTCC No. 25301), Brevibacterium sp. (MTCC 25254), Methanothermobacter sp. (MTCC No. 25268), Methanolobus sp. (MTCC No. 25302), Thermotoga sp. (MTCC No. 25304), Methanosarcina sp. (MTCC No. 25300), Clostridium sp. (MTCC No. 25264), Methanobacterium sp. (MTCC No. 25266) and Lactobacillus sp. (MTCC No. 25282), Moorella sp. (MTCC No. 25267) and Methanosaeta sp. (MTCC No. 25303), Pyrococcus sp. (MTCC No. 25305) and Shewanella sp. MTCC 25020 and wherein the sulfide oxidizing microbes are selected from the group consisting of Pseudomonas stutzeri (MTCC 25027), Arthobacter sp. (MTCC 25028), Achromobacter xylooxidan (MTCC 25024), Bacillus subtilis (MTCC 25026), Pseudomonas aeruginosa (MTCC 5389), Lysinibacillus sp. (MTCC 5666), Pseudomonas putida (MTCC 5385).

15. The process as claimed in claim 12, wherein the hydrogen producing microbes are Enterobacter aerogenes (MTCC 25016).

16. A system for production of methane rich biogas from organic wastes, the system comprising: a) a series of reactors configured for processing a feed slurry; and b) a series of loop reactors for providing a blend of microbes, wherein the series of loop reactors are connected in loop to the series of reactors configured for processing the feed slurry and, wherein each of the series of the loop reactors is of 1/500.sup.th volume of each of the corresponding reactor of the series of the reactors, and wherein the series of the reactors are provided with agitators and drumbeat sticks.

17. The system as claimed in claim 16, wherein the series of the reactors for processing the feed slurry comprises reactors R1, R2, R4, R6, and R8 connected in series, and wherein the series of the loop reactors comprises reactors R3, R5, R7, and R9 connected in loop to the reactors R2, R4, R6, and R8, respectively, and an additional loop reactor R10 connected to R6 and R8.

18. The system as claimed in claim 17, wherein the reactor R8 is of ≥3 times volume than that of R2, R4, or R6, and wherein the reactor R1 is maintained at a temperature in a range of 70-90° C., the reactors R2, R4, R6, and R8 are maintained at a temperature in a range 30-50° C., and wherein the reactor R8 is provided with a supply of FeCl.sub.3.

19. The system as claimed in claim 17, wherein the reactors R3 and R5 are provided with a blend of microbes comprising hydrolytic acidogenic, acetogenic and methanogenic microbes, which are supplied to the reactors R2 and R4, respectively, and wherein the reactors R7 and R9 are provided with a blend of microbes comprising hydrolytic acidogenic, acetogenic, methanogenic, and sulfide oxidizing microbes, which are supplied to the reactors R6 and R8, respectively, and wherein the reactor R10 is provided with a blend of microbes comprising hydrogen producing microbes, which is supplied to the reactors R6 and R8.

Description

DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0048] FIG. 1: Schematic representation of anaerobic digestion process for production of methane rich biogas.

[0049] FIG. 2: Variation in pH through a single cycle of bio methanation using paddy straw as feedstock.

[0050] FIG. 3: Variation in pH of different reactors of present invention on daily basis during continuous mode operation using paddy straw as feed stock.

[0051] FIG. 4: Variation in pH through a single cycle of bio methanation using MSW as feedstock.

[0052] FIG. 5: Variation in pH of different reactors of present invention on daily basis during continuous mode production using paddy straw as feedstock.

DETAILED DESCRIPTION OF THE INVENTION

[0053] Bio-methanization is a process by which organic material is microbiologically converted under anaerobic conditions to biogas. Bio-methanation of complex organic materials is performed by the interplay of essentially three microorganism groups, known as: [0054] 1. Hydrolytic fermentative bacteria; [0055] 2. Hydrogen producing acetogenic bacteria; and [0056] 3. Methanogenic bacteria which consume hydrogen and acetate.

[0057] In the process of bio-methanization the products of the first group are processed by the second microorganism group and the products of the second group are processed by the third group. As a result, the main products, methane, and carbon dioxide, are produced from complex biopolymers.

[0058] The present invention relates to a process of producing a biogas. More particularly, it relates to a sequential anaerobic digestion process for production of methane rich biogas using different kind of organic wastes. One main advantage of the present invention is that the method and a system for conversion of organic waste into biogas provides an increased yield of biogas along with the process being more time and cost effective.

[0059] Existing methods for bio methanation or anaerobic digestion talks about only the conversion of organics to biogas. However, the present invention focuses on minimizing the short channelling of unprocessed organic waste from reactor, self-control biochemical functions during the whole process, lowering down the pH fluctuations, maintaining high microbial count of log-phase/young consortium of selective nature, stabilizing different microbial population, lessening feedback inhibition, and minimizing the scum formation.

[0060] Further, the invention also relates to a novel method for production of methane rich biogas in anaerobic systems using multiple reactors and self-controlled biochemical functions through different types of on-site selective enriched microbial consortium production.

[0061] The present invention describes a sequential anaerobic digestion process for the production of methane rich biogas using different kind of organic wastes, wherein said process comprises of following steps: [0062] (a) Preparing a feed: Preparing an organic waste feed by subjecting the organic waste to a size reduction of 1-5 mm, through a process selected among cutting, shredding, and pulverization; [0063] (b) Pretreating of organic waste feed: optionally pretreating the organic waste feed of reduced size through process selected among hydrothermal treatment, extrusion, ozonation, hydrodynamic cavitation and combination thereof; [0064] (c) Preparing a feed slurry: mixing the organic waste feed obtained from step a) i with water to prepare a feed slurry having 25-50% of total solid (TS) (w/w); [0065] (d) Processing the feed slurry: transferring the feed slurry obtained from step c) through a series of reactors, wherein each reactor is attached with a small on-site selective bioinoculant generation reactor, and wherein the bioinoculant generation reactor is of 1/500.sup.th size of the biogas production bioreactor; and [0066] (e) Removal of H.sub.2S and CO.sub.2: In situ removal of H.sub.2S and CO.sub.2 from final biogas obtained from step (d).

[0067] The present invention describes the microbial consortium identified for added into series of reactors at different phases of the sequential process to produce methane rich biogas.

[0068] The present invention also describes the microbial blend identified for reactors R7 and R9 which include microbes for digesting the organic waste such as Pseudomonas stutzeri (MTCC 25027), Arthobacter sp. (MTCC 25028), Achromobacter xylooxidan (MTCC 25024), Bacillus subtilis (MTCC 25026), Pseudomonas aeruginosa (MTCC 5389), Lysinibacillus sp. (MTCC 5666), Pseudomonas putida (MTCC 5385).

[0069] The present invention also describes microbial blend identified to be used in the reactor R10 i.e., hydrogen producing culture, which consist of Enterobacter aerogenes MTCC 25016.

EXAMPLES

Method for Production of Methane Rich Biogas

[0070] Step 1. Size Reduction: The biomass/organic waste is subjected for size reduction through cutting or shredding or pulverization and the size to be 1-5 mm size.

[0071] Step 2. Pretreatment: The size reduced biomass/organic waste is subjected to pretreatment if the lignin content is more than 10% of the biomass/organic waste. The pretreatment may include but not limited to hydrothermal treatment, extrusion, ozonation and hydrodynamic cavitation.

[0072] Step 3. Slurry preparation: The pre-treated biomass is mixed with water to make the feed slurry having 25-50% of TS (w/w) and send to R1. The water can be raw water or recycled water from the process. R1 is to be maintained at 70-90° C. with intermittent mixing for 5-24 hrs.

[0073] Step 4. Processing: The feed slurry from the R1 is transferred to R2 along with addition of water to make the final TS in the reactor 8-12% (w/w). R2 is to be maintained at 30-50° C. with intermittent mixing for 48-72 hours. R2 is connected in loop to R3 which is 1/500.sup.th volume of R2. Microbial blend containing the microbes suitable for hydrolysis, acidogenesis, acetogenesis and methanogenesis are grown in R3 and added to R2. The initial microbial count of R2 is maintained to be 10.sup.4 to 10.sup.5 CFU/g of feed slurry. Intermittent mixing in R2 is provided by agitators or by circulating the slurry or by the gas produced. R2 have a set of drumbeat sticks on the exterior top of reactor to break the scum. R3 is in liquid communication at bottom of R2 and the microbes enriched in R3 are used to maintain microbial count inside R2. The microbe dosing from R3 to R2 is done by transferring 80% of R3 content to R2, at every 24 hours interval and the volume of R3 is make up using the combination of slurry from R2 and nutrient rich waste/wastewater like molasses, spent wash, fruit waste.

[0074] Step 5. Slurry from R2, after 48-72 hours, transferred to R4 which is connected in loop to R5. The R4 and R5 operation is done in exactly similar way to R2 and R3 operation with few modifications as follows. The feed slurry from the R2 is transferred to R4 and is maintained at 30-50° C. with intermittent mixing for 48-72 hours. R4 is connected in loop to R5 which is 1/500.sup.th volume of R4. Microbial blend containing the microbes suitable for hydrolysis, acidogenesis, acetogenesis and methanogenesis are grown in R5 and added to R4. The initial microbial count of R4 is maintained to be 10.sup.4 to 10.sup.5 CFU/g of feed slurry. Intermittent mixing in the R4 is provided by agitators or by circulating the slurry or by the gas produced. R4 have a set of drumbeat sticks on the exterior top of reactor to break the scum. R5 is in liquid communication at bottom of R4 and the microbes enriched in R5 are used to maintain microbial count inside R4. The microbe dosing from R5 to R4 is done by transferring 80% of R5 content to R4, at every 24h interval and the volume of R5 is make up using the combination of slurry from R4 and nutrient rich waste/wastewater like molasses, spent wash, fruit waste.

[0075] Step 6. Slurry from R4, after 48-72 hours is transferred to R6 which is connected in loop to R7. The R6 and R7 operation is done in exactly similar way to R4 and R5 operation with small modifications as follows. The feed slurry from the R4 is transferred to R6 and is maintained at 30-50° C. with intermittent mixing for 48-72 hours. R6 is connected in loop to R7 which is 1/500.sup.th volume of R6. Microbial blend containing the microbes suitable for hydrolysis, acidogenesis, acetogenesis and methanogenesis along with sulfide oxidizing bacteria are grown in R7 and added to R6. In addition, hydrogen producing consortia specifically grown in R10 is also added to R6. The ratio of cultures from R7 and R10 is maintained to be 2:1. The initial microbial count of R6 to be maintained 10.sup.6 to 10.sup.9 CFU/g of feed slurry. Intermittent mixing in the R6 is provided by agitators or by circulating the slurry. The biogas produced from R6 is collected to the storage balloon. R6 has a set of drumbeat sticks on the exterior top of reactor to break the scum. R7 is in liquid communication at bottom of R6 and the microbes enriched in R7 are used to maintain microbial count inside R6. The microbe dosing from R7 to R6 is done by transferring 80% of R7 content to R6, at every 24h interval and the volume of R7 is make up using the combination of slurry from R6 and nutrient rich waste/wastewater like molasses, spent wash, fruit waste.

[0076] Step 7. Slurry from R6, after 48-72 hours is transferred to R8 which is connected in loop to R9. The R8 and R9 operation is also done in more or less similar way to R6 and R7 operation but with modifications in size and operation as follows. The feed slurry from the R6 is transferred to R8 and is maintained at 30-50° C. with intermittent mixing for 72-144 hours. While transferring the feed slurry from R6 to R8, the stream is mixed with FeCl.sub.3 at 0.01-0.05% concentration. R8 is at least 3 times in volume to R2, R4 and R6 to manage the increased HRT. R8 is connected in loop to R9 which is 1/500.sup.th volume of R8. Microbial blend containing the microbes suitable for hydrolysis acidogenesis, acetogenesis and methanogenesis along with sulfide oxidizing bacteria are grown in R9 and added to R8. In addition, hydrogen producing consortia specifically grown in R10 is also added to R8. The ratio of cultures from R9 and R10 is maintained to be 2:1. The initial microbial count of R8 to be maintained 10.sup.9 to 10.sup.12 CFU/g of feed slurry. Intermittent mixing in the R8 is provided by agitators or by circulating the slurry. The biogas produced from R8 is collected to the storage balloon. R8 has a set of drumbeat sticks on the exterior top of reactor to break the scum. R9 is in liquid communication at bottom of R8 and the microbes enriched in R9 are used to maintain microbial count inside R8. The microbe dosing from R9 to R8 is done by transferring 80% of R9 content to R8, at every 24 hours interval and the volume of R9 is make up using the combination of slurry from R8 and nutrient rich waste/wastewater like molasses, spent wash, fruit waste.

[0077] Step 8. The hydrogen producing culture in R10 is grown continuously to dose the R7 and R9. The temperature for R10 is maintained at 60-70° C. and the combination of feed slurry from R8 and nutrient rich waste/wastewater like molasses, spent wash, fruit waste.

[0078] Step 9. Production of biogas: The hydrogen rich biogas produced from R10 is also connected to R8 along with feed slurry to increase the methane content and reduce the CO.sub.2 content of the biogas.

[0079] Step 10. Purification: Biogas produced from R6 and R8 transferred to balloon and is rich in methane due to hydrogenotrophic methanogenesis (CO.sub.2+H.sub.2.fwdarw.CH.sub.4) facilitated by hydrogen producing culture and hydrogen rich biogas producing from R10. Further, the biogas is devoid of or having minimum concentration of H.sub.2S due to the sulfide oxidizing bacteria. The biogas after subjecting to minimum purification can be compressed and filled in cylinder bank.

[0080] The seed bioinoculant used in the current invention is similar for R2 and R4, R6, R8 and R10. However, the onsite enrichment over the time changes the actual composition of the microbial blend and will sustain the composition due to regular dosing of the same.

[0081] The microbial blend used for R2 and R4 during seed include the microbial blend (i) acetolactic methanogens is selected from a group consisting of Desulfovibrio sp. (MTCC No. 25301), Brevibacterium sp. (MTCC 25254), Methanothermobacter sp. (MTCC No. 25268), Methanolobus sp. (MTCC No. 25302), Thermotoga sp. (MTCC No. 25304); (ii) hydrogenotrophic methanogens selected from the group consisting of Methanosarcina sp. (MTCC No. 25300), Clostridium sp. (MTCC No. 25264), Methanobacterium sp. (MTCC No. 25266) and Lactobacillus sp. (MTCC No. 25282); (iii) methanotrophic archaea selected from the group consisting of Methanosaeta sp. (MTCC No. 25303), Moorella sp. (MTCC No. 25267) and Lactobacillus sp. (MTCC No. 25282); and (iv) electroactive bacteria selected from a group consisting of Clostridium sp. (MTCC 25264), Methanosaeta sp. (MTCC No. 25303), Pyrococcus sp. (MTCC No. 25305) and Shewanella sp. MTCC 25020 (as disclosed in the Patent Application 201921037470).

[0082] Similarly, the seed bioinoculant used in R7 and R9 include all the microbes mentioned for R2 and R4 along with sulfide oxidizing bacteria that include but not limited to Pseudomonas stutzeri (MTCC 25027), Arthobacter sp. (MTCC 25028), Achromobacter xylooxidan (MTCC 25024), Bacillus subtilis (MTCC 25026), Pseudomonas aeruginosa (MTCC 5389), Lysinibacillus sp. (MTCC 5666), Pseudomonas putida (MTCC 5385).

[0083] The seed bioinoculant used in R10 is a microbial blend of following but not limited to Enterobacter aerogenes MTCC 25016.

Example 1

Bio Methanation of Different Types of Organic Waste

[0084] The efficiency of bio methanation process was evaluated using different feedstock, viz., organic fraction of municipal solid waste (MSW), press mud, cattle dung, paddy straw and water hyacinth (Table 1). Different combinations of experiments were performed with the selected feedstock including the pretreatment options. All the selected feedstock checked and removed any non-biodegradable materials. Shredding/size reduction is carried out for MSW, paddy straw and water hyacinth but for press mud and cattle dung size reduction is not required. Different pretreatment options included for MSW, paddy straw and water hyacinth but no pretreatment is required for press mud and cattle dung. TS content for R1 in case of MSW, press mud, cattle dung and water hyacinth kept as such without any dilution but in case of paddy straw, the TS content of R1 maintained at 50%. The hydraulic retention time is different for each feedstock based on their complexity as designated in Table 1. Typical single stage bio methanation using the same biocatalyst is considered as control operation. After the designated pretreatment, feedstock is subjected to bio methanation. Temperature of the digester is maintained at 50° C. and % TS is maintained like R2 digester of present invention.

TABLE-US-00001 TABLE 1 Experimental conditions adapted to evaluate the potential of present invention using different feedstocks Conditions Conditions Conditions Conditions for R1 for R2 for R4 and for R8 (% TS (% TS R6 (% TS (% TS loading, loading, loading, loading, Temp. Temp. Temp. Temp. (° C.) Size Pre- (° C.) and (° C.) and (° C.) and and HRT Exp Feed- % reduction treatment HRT HRT HRT (h), FeCl3 No. stock TS (mm) adapted (h)) (h)) (h)) (%)) 1 Municipal 25-35 Crushing Hydro- % TS, 25 % TS, 10 % TS, <10 % TS, <10 Solid (1-2 mm) thermal Temp., 60 Temp., 30 Temp., 30 Temp., 30 Waste (121° C. HRT, 12 HRT, 48 HRT, 48 HRT, 72 (MSW) and 15 FeCl3, 0.02 lbs. for 15 min) 2 Ozonation % TS, 30 % TS, 12 % TS, <12 % TS, <12 (dose at 5 Temp., 50 Temp., 40 Temp., 40 Temp., 40 g/h for 30 HRT, 12 HRT, 60 HRT, 60 HRT, 84 min) FeCl3, 0.01 3 Extrusion % TS, 35 % TS, 12 % TS, <12 % TS, <12 (50 kg/h) Temp., 70 Temp., 40 Temp., 40 Temp., 40 HRT, 8 HRT, 72 HRT, 72 HRT, 96 FeCl3, 0.02 4 Press 25-30 NR NR % TS, 26 % TS, 13 % TS, <13 % TS, <13 Mud Temp., 50 Temp., 40 Temp., 40 Temp., 40 HRT, 8 HRT, 48 HRT, 48 HRT, 96 FeCl3, 0.04 5 Cattle 18-26 NR NR % TS, 21 % TS, 10 % TS, <10 % TS, <10 dung Temp., 70 Temp., 40 Temp., 40 Temp., 40 HRT, 5 HRT, 48 HRT, 48 HRT, 72 FeCl3, 0.05 6 Paddy 85-90 Shredding Hydro- % TS, 40 % TS, 10 % TS, <10 % TS, <10 straw (0.5 mm) thermal Temp., 80 Temp., 40 Temp., 40 Temp., 40 (121° C. HRT, 18 HRT, 48 HRT, 72 HRT, 120 and 15 FeCl3, 0.02 lbs. for 15 min) 7 Shredding Hydro- % TS, 50 % TS, 12 % TS, <12 % TS, <12 (3 mm) dynamic Temp., 90 Temp., 50 Temp., 50 Temp., 50 cavitation HRT, 12 HRT, 72 HRT, 72 HRT, 144 FeCl3, 0.01 8 Shredding Extrusion % TS, 40 % TS, 12 % TS, <12 % TS, <12 (5 mm) (50 kg/h) Temp., 85 Temp., 45 Temp., 45 Temp., 45 HRT, 24 HRT, 60 HRT, 60 HRT, 132 FeCl3, 0.01 9 Water 15-25 Shredding Hydro- % TS, 25 % TS, 12 % TS, <12 % TS, <12 Hyacinth (1 mm) dynamic Temp., 60 Temp., 40 Temp., 40 Temp., 40 cavitation HRT, 15 HRT, 48 HRT, 72 HRT, 120 FeCl3, 0.02 10 Shredding Ozonation % TS, 25 % TS, 12 % TS, <12 % TS, <12 (2 mm) (dose at 10 Temp., 75 Temp., 45 Temp., 45 Temp., 45 g/h for 30 HRT, 10 HRT, 60 HRT, 60 HRT, 132 min) FeCl3, 0.03 11 Shredding Extrusion % TS, 25 % TS, 12 % TS, <12 % TS, <12 (4 mm) (50 kg/h) Temp., 80 Temp., 50 Temp., 50 Temp., 50 HRT, 14 HRT, 72 HRT, 72 HRT, 144 FeCl3, 0.02

TABLE-US-00002 TABLE 2 Comparative evaluation of present invention over the conventional single stage bio methanation % TS % COD Biogas yield Methane H2S removal removal (m3/Ton) Content (%) content (ppm) HRT (hrs.) Control Control Control Control Control Control Exp (Single (Single (Single (Single (Single (Single No. stage) P.I stage) P.I. stage) P.I. stage) P.I. stage) P.I. stage) P.I. 1 48-51 74-77 52-56 76-79 60-75 110-128 69-70 72-74  900-1700 40-80 336-442 228-280 2 52-56 78-82 57-63 75-78 64-78 116-140 68-70 74-76  900-1700 40-80 336-442 228-280 3 50-54 75-79 54-61 74-77 62-72 112-134 68-71 73-76  900-1700 40-80 336-442 228-280 4 58-61 76-83 63-65 79-87 80-90 144-162 69-71 72-76  800-1600 60-90 336-442 240-250 5 62-66 73-75 66-70 78-81 45-60 105-124 70-72 71-76 1400-2700  70-110 336-442 220-230 6 40-46 63-67 46-53 69-76 242-266 324-356 68-70 72-75  400-1000 20-50 504-576 330-380 7 51-54 72-75 55-59 76-81 256-288 328-359 69-71 74-75  400-1000 20-50 504-576 330-380 8 48-52 69-73 53-56 74-78 250-274 326-352 69-71 74-76  400-1000 20-50 504-576 330-380 9 50-56 76-81 54-61 80-87 62-71 82-93 67-70 73-76 500-900 30-70 504-576 300-370 10 52-57 78-84 55-61 82-86 66-78 86-95 68-71 71-74 500-900 30-70 504-576 300-370 11 49-53 78-82 54-57 81-86 64-72 84-89 69-72 72-75 500-900 30-70 504-576 300-370 P.I. in the above table stands for present invention.

Example 2

Monitoring of pH Fluctuation

[0085] Experiments were performed using MSW and paddy straw in continuous mode for establishing the pH stability of present invention against the conventional bio methanation. The selected feedstock was checked, and all the non-biodegradable material was removed from it manually. Shredding or size reduction is carried out followed by designated pretreatment. TS content for R1 in case of MSW is kept as such without any dilution but in case of paddy straw, the TS content of R1 maintained at 50%. After the designated pretreatment, feedstock is subjected to bio methanation. Temperature of the digester is maintained at 50° C. and % TS is maintained like R2 in the digester. The hydraulic retention time adapted in each reactor is different for each feedstock based on their complexity and the same is designated in Table 3. Typical single stage bio methanation using the same biocatalyst is considered as control operation for both the feedstocks. HRT for control operation considered as 14 days for MSW and 24 days for paddy straw. Rest all other conditions maintained similar to test conditions.

[0086] The results obtained from the experiment with paddy straw and MSW has been shown in FIGS. 1 and 3 wherein a clear demarcation of pH stability against the conventional bio methanation is observed. The operating pH of each reactor has showed mere fluctuation for number of days using both MSW and paddy straw as feedstock (FIGS. 2 and 4). This behavior in each reactor is due to self-controlled biochemical function of each reactor which helps in the proliferation of stable microbial dynamics in turn resulting in higher biogas yields, high substrate conversion and low HRT.

TABLE-US-00003 TABLE 3 Experimental conditions adapted for establishment of pH stability Conditions for Conditions for Conditions for Conditions for R1 (% TS R2 (% TS R4 and R6 (% TS R8 (% TS Pretreatment loading, Temp. loading, Temp. loading, Temp. loading, Temp. adapted and other (° C.) and (° C.) and (° C.) and (° C.) and HRT Feedstock conditions HRT (h)) HRT (h)) HRT (h)) (h), FeCl3 (%)) MSW Crushing (1-2 mm) % TS, 25 % TS, 10 % TS, <10 % TS, <10 (% TS: 25-35) Hydro-thermal Temp., 60 Temp., 30 Temp., 30 Temp., 30 (121° C. and 15 lbs. HRT, 12 HRT, 48 HRT, 48 HRT, 72 for 15 min) FeCl3, 0.02 Paddy Shredding (5 mm) % TS, 40 % TS, 12 % TS, <12 % TS, <12 straw Extrusion Temp., 85 Temp., 45 Temp., 45 Temp., 45 (% TS: 85-90) (50 kg/h) HRT, 24 HRT, 60 HRT, 60 HRT, 132 FeCl3, 0.01

Technical Advancements Contributed by the Present Invention:

[0087] Minimizing the short channelling of unprocessed organic waste from reactor [0088] Self-controlled biochemical functions during whole process [0089] High biogas yield with enriched methane and low/nil sulphide content [0090] Maintaining high microbial count of log-phase/young consortium of selective nature [0091] Low pH fluctuation inside the reactor [0092] Less product feedback inhibition [0093] Shorter hydraulic and solid retention time [0094] Stabilization of different microbial populations [0095] No moving part inside the reactor [0096] Minimizing the scum formation