Title of Invention	PROCEDURE FOR THE PRODUCTION OF SEVERAL FOLDS MORE BIOGAS WITH A HIGHER CALORIFIC VALUE AT AMBIENT TEMPERATURES (25-370C) AS WELL AS AT LOW TEMPERATURES (BELOW 150C)
Abstract	1. A process for the production of several folds more biogas with a higher calorific value at ambient temperatures (25-37°C) as well as at low temperatures (below 15°C) comprises the following steps of : a) stabilization of biogas digester by filling a slurry of gobar or of carbonaceous waste to a biogas digester volume and maintaining at ambient temperature ranging from 25°C to 37°C in an air tight condition; b) development of stabilized biogas digester and production of several folds more biogas at ambient temperature ranging from 25°C to 37°C by feeding a slurry of gobar containing ammonium carbonate, di-potassium hydrogen phosphate and water miscible organic solvents such as methanol; . c) production of biogas at low temperature, below 15°C, from the developed biogas digester by feeding a slurry of gobar with reduced quantities of ammonium carbonate, di-potassium hydrogen phosphate and methanol; d) normalization of the developed biogas digester at ambient temperature ranging from 28°C to 32°C by feeding a slurry of gobar.

Title of Invention

PROCEDURE FOR THE PRODUCTION OF SEVERAL FOLDS MORE BIOGAS WITH A HIGHER CALORIFIC VALUE AT AMBIENT TEMPERATURES (25-370C) AS WELL AS AT LOW TEMPERATURES (BELOW 150C)

Abstract

1. A process for the production of several folds more biogas with a higher calorific value at ambient temperatures (25-37°C) as well as at low temperatures (below 15°C) comprises the following steps of : a) stabilization of biogas digester by filling a slurry of gobar or of carbonaceous waste to a biogas digester volume and maintaining at ambient temperature ranging from 25°C to 37°C in an air tight condition; b) development of stabilized biogas digester and production of several folds more biogas at ambient temperature ranging from 25°C to 37°C by feeding a slurry of gobar containing ammonium carbonate, di-potassium hydrogen phosphate and water miscible organic solvents such as methanol; . c) production of biogas at low temperature, below 15°C, from the developed biogas digester by feeding a slurry of gobar with reduced quantities of ammonium carbonate, di-potassium hydrogen phosphate and methanol; d) normalization of the developed biogas digester at ambient temperature ranging from 28°C to 32°C by feeding a slurry of gobar.

Full Text	FORM 2 THE PATENTS ACT, 1970 (39 Of 1970) COMPLETE SPECIFICATION (See sections 10 ) 1. Title of the invention 1. Procedure for the production of several folds more biogas with a higher calorific value at ambient temperatures (25-37°C) as well as at low temperatures (below 15°C). 2. Repeat the columns (a) to (c) if there are more than one applicant (a) 3. Agharkar Research Institute (b) 4. G.G. Agarkar Road, Pune-411 004, Maharashtra, India. (c)5. Nationality : Indian 3. Insert the name in full. The family or principal name in the beginning if the applicant is a natural person. 4. Insert the complete address including postal index number/ Code and State and /or country The following specification particularly, describes the nature of the invention and the manner in which it is to be Performed. 5. Insert the nationality Strike out in case of provisional Specification GARNTED 29/1/2004 ORIGINAL 162/MUMNP/20003 06/02/03 Procedure for the production of several folds more biogas with a higher calorific value at normal ambient temperatures (25-37°C) as well as at low temperatures (below 15°C) This invention relates to an improved process for obtaining several folds more biogas with a high alorific value at low temperatures (10-15°C) as well as at normal ambient temperatures 25-37°C). n the past a number of attempts have been described for obtaining biogas from cattle dung gobar) at low temperatures. At low temperatures growth of methanogens, methane-producing bacteria, is restricted and methane formation is slowed down. Similarly, activity and growth rate of other bacteria, which produce acetate, CO2 etc also, reduced at low temperature resulting in lecreased production of acetate and CO2. Methanogens are limited in their available substrates acetate and CO2). This narrows range of substrates that can support growth of methanogens. At ow temperatures, methane fermentations may continue slowly and possibly resulting in an nactivation of methane formation and stopped at low temperatures. Therefore in winter, where he temperature of biogas digesters reaches below 15°C, functioning of biogas digesters is everely affected. Ve have now found that biogas can be produced at low temperatures, 10-15°C, in a good yield several folds more) by a simple procedure using ordinary chemicals as activators along with gobar slurry. If a chemical, which activates growth of methanogens, is supplemented (provided) 0 active methanogens, methane formation gets activated and ultimately a dense culture of nethanogens (a cell-mass) is developed. Similarly ammonium carbonate, ammonia solution, mmonium chloride, diammonium phosphate like ammonium ion producing compounds can be used as a nitrogen source as methanogens utilize free NH4 and it also helps in maintaining pH. We have used ammonium carbonate because it is cheap and very easy to handle. Potassium (K) and PO4 (Phosphate) requirement is satisfied by di-potassium hydrogen phosphate (K2HPO4). Vitamins, trace minerals and other essential components required for the growth of bacteria are vailable from gobar. On this basis, an activator, an aqueous homogeneous mixture, is prepared vith the following composition (per ml of aqueous activator): ammonium carbonate; 64 Μ mol, ii-potassium hydrogen phosphate; 3 μ mol and methanol; 12 m mol. In object of the present investigation is to produce several folds more biogas by a commercial crocess, which will give good yields of biogas at low temperatures as well as at normal ambient smperatures also. Another object is to produce biogas at low temperature by a semicontineous irocess without the use of highly specialized and expensive equipments and chemicals. A still urther object is to produce biogas with a higher calorific value i.e. biogas containing higher per entage of methane. an carrying out the process of the present investigation, we have found that the use of essentially lomogeneous aqueous-methanolic solvents allows a greater degree of intimate contact between substrates and the microorganisms and thus produces higher yields of biogas. The solvents found. useful are those miscible with water such as methanol, which promotes growth of some methanogens. Also found desirable as an excess of ammonium carbonate, which prevents formation of clumps of methanogens or helps in disaggregation of methanogens resulting in increasing the permeability of the substrates into the cells of methanogens. The process of the present investigation can be carried out using practically any animal waste, agricultural waste, industrial waste, canteen waste etc in absence of oxygen and in presence of methanogens, however we prefer to use, the cattle dung (gobar) since it is readily available and is also a good source of methanogens. Cattle dung is used as a common substrate to run biogas plants in India. In India, gobar gas plants are popular for generating fuel for domestic purposes. For best results it is necessary to use fifty per cent gobar slurry prepared in water which gives about 9-10 per cent of total solids. While carrying out the present process, it is desirable to carry out the experiments at the ambient temperature between 25-37°C to stabilize the digester. Best results are obtained at a temperature of 30-35°C. Now the procedure will be more clearly described with reference to Figure of accompanying drawing wherein Figure shows the schematic diagram of a digester for the production of biogas. Referring to Figure, a sturdy container which acts as an anaerobic digester (1), is having an inlet pipe (2) for feeding gobar slurry. Other side of the sturdy container (1) has the outlet pipe (3) with a valve for taking out effluent, which is collected in effluent container (4). There is one more outlet pipe (5) at the top of the digester with a valve for connecting outlet for biogas collected in biogas collector (6). After the stabilization of the 1.150 L glass digester (Fig.l) containing 940 ml of gobar slurry is fed daily with 30 ml of fresh gobar slurry containing varying concentrations of ammonium carbonate (320-960 μ mol), di-potassium hydrogen phosphate (15-45 μ mol) and methanol (60-180 m mol). Best results are obtained when the feeding 30 ml of gobar slurry contains ammonium carbonate; 640 u. mol; di-potassium hydrogen phosphate;30 μ mol and methanol; 120 m mol . The yield of gobar gas is 3-7 fold higher than that of the control digester depending upon concentrations of components of activators. The biogas produced is rich in methane content as compared to that of control. The increase in volatile acids indicates that the activator also activates the growth of nonmethanogenic bacteria. The population of methanogens is also increased indicating an increase in the intensity of factor F420. Factor F420 takes part in methane formation and methane produced is directly proportional to concentration of F420. After development of biogas digester as above, it is maintained at ambient temperature, 12-15°C and activator with lower concentration is fed daily with 30 ml of gobar slurry containing about 10 per cent total solids. At a concentration of ammonium carbonate; 192 μ mol, di-potassium hydrogen phosphate; 9 μ mol and methanol; 36 m mol in the 30 ml of gobar slurry, the biogas produced is equivalent to the biogas formed by control at an ambient temperature, 30-35°C and it is rich in methane content indicating increase in calorific value of biogas. The effluent obtained will be rich in N:P:K as the added activator consists of ammonium carbonate and di-potassium hydrogen phosphate. The rate of biogas formation is constant. The volatile acids increased indicating the activator also activates the growth of nonmethanogenic bacteria and the increased concentration of volatile acids is not toxic to methanogens. The growth of methanogens as well as concentration of factor F420 is also maintained or increased. This is in sharp contrast to statements in the prior art regarding the biogas production by other processes herein before described and to our experience with these processes. The following examples illustrate in detail the production of biogas from cattle dung (gobar), at lower temperature (10-15°C) as well as at ambient temperatures (25-37°C), in high yields with higher calorific value by using chemicals to activate the process. The examples are by way of illustration and are not intended to be a limitation of the invention. The present investigation includes stabilization of digester, development of digester, production of biogas at low temperatures and normalization of digester at normal ambient temperature. Stabilization of a digester : In a 1.150-L glass digester (Fig.l), 940-ml of gobar slurry is kept in an anaerobic condition for 10 days at an ambient temperature (25-37°C). When a sufficient biogas is produced containing 45-50 per cent of methane, then it is confirmed that the digester is stabilized. Development of a digester : The stabilized digester is fed daily with 30 ml of gobar slurry along with varying concentrations of activator. When a biogas is produced with a constant rate containing 65-69 per cent of methane, then it is assumed that the digester is developed. Microscopic observations of effluent show several folds higher population of methanogens than that of control. Example 1 Two, 1.150 liter digesters (Fig.l) containing 940 ml of gobar slurry in each are stabilized at 30-35°C, which produced about 500 ml of biogas per day after feeding 30 ml of gobar slurry every day. The biogas contains about 51 per cent methane and 48 per cent CO2. Out of these two digesters one is fed with 30 ml of gobar slurry per day and maintained as a control. Another digester is fed daily with 30 ml of gobar slurry along with activator (5 ml) containing ammonium carbonate; 320 μ mol, di-potassium hydrogen phosphate; 15 μ mol and methanol; 60 m mol. Biogas produced, rate of biogas production, analysis of biogas, pH and composition of volatile acid of effluent slurry are determined. An average data of 30 days is presented in Table 1. A 3-fold more biogas with a high calorific value accounting 68 per cent methane is produced by the activator. supplemented digester as compare to that of control. A dense population of methanogens was developed in the experimental digester. Methanogens in the experimental digester showed bright epifluorescence under ultraviolet light when observed under microscope and cells of clump forming methanogens are disaggregated. Example 2 An experiment is carried out as in Example 1, and a 30 ml of gobar slurry containing activator (7.5 ml) with concentrations: ammonium carbonate; 480 u. mol, di-potassium hydrogen phosphate;22.5 μ mol and methanol;90 m mol is fed daily to the experimental digester for 30 days. The results (Table 1) indicate that there is a 4 -fold increase in biogas with 69 per cent of methane as compare to that of control. The microscopic observations showed that the population of methanogens was higher than that of control. Example 3 An experiment is conducted as in Example 1. An activator (10 ml) with the following concentrations : ammonium carbonate; 640 μ mol, di-potassium hydrogen phosphate; 30 μ mol and methanol; 120 m mol in 30 ml of gobar. slurry is fed to the experimental digester. The measurements indicate that there is a 5-fold increase in biogas as compared to that of control. The biogas produced in the experimental digester contains 68 per cent of methane (Table 1). The population of methanogens is more than the control (Table 4) and they showed bright epifluorescence under ultraviolet light when observed under the microscope. Example 4 An experiment is conducted as above. The gobar slurry, 30 ml, is fed with activator (15 ml) with the following concentrations: ammonium carbonate; 960 u. mol, di-potassium hydrogen phosphate; 45 Μ mol and methanol; 180 m mol. The measurements show that there is about 7-fold increase in biogas with 69 per cent of methane as compared to that of control digester (Table 1). A very dense population of methanogens was developed and showed very bright epifluorescence under ultraviolet light. Production of biogas at low temperature: The developed digesters, as above are shifted to low temperatures (12-15°C) and the biogas formation is studied. Example 5 In view to study the biogas formation at low temperature (12-15°C), the digesters in Example 3 are shifted to a cold room, where the temperature is maintained at 12-15°C. For the control digester, 30 ml of gobar slurry is fed daily and for the experimental digester, 30 ml of gobar slurry along with activator (3 ml) having concentrations: ammonium carbonate; 192 u. mol, di-potassium hydrogen phosphate; 9 μ mol and methanol; 36 m mol is fed daily. With this treatment a 5-fold increase in biogas with 63-68 per cent of methane is obtained as compared to that of control (Table 2) and it is almost equivalent to the biogas produced at 30-35 °C by the control digester (Table 1). The experiment is conducted for 60 days. During the period, the rate of biogas formation, methane per centage, yield of biogas is almost constant or increased. There is an increase in volatile acids in the effluent of experimental digester, however the higher concentration of volatile acids is not toxic to methanogens. The overall population of methanogens is slightly decreased (Table 4). The cells of clump-forming methanogens (Methanosarcina) are separated or disaggregated and showed bright epifluorescence under ultraviolet light. Thus, this semicontinuous process illustrates a further advantage of obtaining more biogas at low temperatures (below 15°C). Example 6 The digesters maintained at 12-15°C in Example 5, are then maintained at 10-12°C in a cold room and biogas formation is studied for 30 days. The experimental digester was fed daily with 30 ml gobar slurry containing 3 ml of activator. In both cases, biogas formation was severely affected. Eventhen the biogas produced in the experimental digester is two folds higher than that of the control. The methane percentage in the biogas produced by experimental digester is 69-70, whereas in the control it is 54-55 percent (Table 2). At 10-12°C also methanogens show bright epifluorescence. However the activity of methanogens is decreased resulting in decrease in the intensity of F420 (Table 4). Normalization of digesters : After the experiments at low temperature, both digesters are shifted to normal ambient temperature (28-32°C), in view to study their functioning at normal ambient temperature. As the bacteria from both digesters are in stress conditions, they took some time for adaptation at normal ambient temperature. Example 7 After studying the digestion at low temperature, digesters in Example 6 are maintained at ambient temperature 28-32°C to study their functioning at normal ambient temperature. In initial 4-5 days the rate of methane formation is slow. However after that the rate of methane formation increased and both digesters produced methane with a constant rate (Table 3). The experimental digester produced more methane as it contains higher population of methanogens (Table 4). Thus after stress conditions also one can get higher biogas than that of control as the activator helps in producing higher population of methanogens. However, biogas decreases with a slow rate as experimental digester is fed with 30 ml of gobar slurry every day along with decreasing quantities of an activator as expected. And after some days the experimental digester was fed with only 30 ml gobar slurry as a normal feeding. METHODOLOGY Stabilization of digester: A digestion of gobar slurry was carried out in 1.150-L fixed dome glass digester (Fig.l) with a working volume of 940 ml. Gobar was diluted 1:1 (wet wt/v) with water and kept in anaerobic condition for 10 days at an ambient temperature (27-32°C). When a sufficient biogas was produced containing 45-50 percent methane then feeding was done at every 24 h for 30 days hydraulic retention time (HRT) using two digesters for the same HRT. Digestion was carried out at normal ambient temperature (25-35°C). Development of digesters: One of these two stabilized digesters is fed daily with 30 ml of gobar slurry only and maintained as a control. Another digester was fed daily with varying concentrations of activator along with 30 ml of gobar slurry and maintained as an experimental digester. Development of digesters was carried out at normal ambient temperature and at 30 days HRT. When the biogas production of experimental digester reaches several fold higher than that of control and contains 65-69 per cent of methane then it is assumed that the digester is developed. Biogas production at low temperature: After the development of digesters, digestion was carried out at 12-15°C in an environmental chamber or in a cold room. Feeding of 30 ml of gobar slurry was done every 24 h to the control digester for 60 days. Similarly, experimental digester was fed daily with 30 ml of gobar slurry containing reduced concentrations of activators for 60 days. After studying the biomethanation at 12-15°C, biogas production was also carried out at 10-12°C. Normalization of digesters: After the digestion at low temperature, digestion was carried out at normal ambient temperature by feeding 30 ml of gobar slurry at every 24 h to the control digester at 30 days HRT and to the experimental digester 30 ml gobar slurry was fed along with decreasing quantities of an activator. Biogas production was compared. ANALYSIS Biogas production was monitored daily by displacement of water. Volatile acids, pH of the slurry and methane content in the biogas were measured at weekly intervals. Microbial counts and intensity of factor F420 in the effluent slurry were also monitored at weekly intervals. Gas analysis: The biogas produced was analyzed for its methane content by using a gas chromatograph (Chemito 3800, Mumbai), equipped with a thermal conductivity detector (TCD) and S.S. column (8' x 1/8") packed with Porapak Q (mesh No. 80/100). Hydrogen (40 ml/min) was used as a carrier gas (Ranade et al 1987). Volatile acids analysis: Volatile acids were analyzed by using a gas chromatograph (Chemito 8510, Mumbai), equipped with flame ionization detector (FID) and S.S. column (8' x 1/8") packed with 10 per cent FFAP on Chemosorb W (HP) 80/100. Nitrogen (40 ml/min) was used as a carrier gas. The temperature of oven, injector and of detector were set to 150,190 and 200°C respectively (Yeole et al 1989). Microbial counts: Methanogens and total bacterial counts were taken by microscopic observation under UV-light and with the bright-field microscope respectively using Neubauer chamber. Active methanogens show bright epifluorescence under UV-light. Nonmethanogens were calculated by subtracting counts of methanogens (fluorescent cells) from counts of total bacteria. Factor F420: Intensity of Factor F42o was measured fluorometrically (Shimadzu Spectrofluorophotometer RF-5301 PC) from alkaline extracts of effluent gobar slurry at Ex-nm 425 and Em-nm 472. To a 9-ml of effluent gobar slurry, 1-ml of 1 N KOH was added and mixed. The extract was centrifuged after 2 h and supernatant was used for fluorometric measurements (Delafontaine et al 1979). Preparation of an Activator: A weighed quantity (2.5 g) of ammonium carbonate and 250 mg of di-potassium hydrogen phosphate was dissolved in a homogeneous mixture of water and methanol (250:250 ml). This homogeneous mixture is called as an Activator. References Cited in the file of this patent Ranade,D.R.,Yeole,T.Y. and Godbole,S.H., (1987),Production of biogas from market waste. Biomass,13, 147-153. Yeole,T.Y.,Ranade,D.R. and Gadre,R.V. (1989),Biogas from liquid waste arising in liver and beef extract production. RERIC International Energy Journal, 11, 35-39. Delafontaine,M.J., Naveau,H.P. and Nyns E.J. (1979), Fluorimetric monitoring of methanogenesis in anaerobic digesters, Biotechnology Letters, 1, 71-74. Table 1 : Production of biogas and volatile acid profile during the development of digesters at an ambient temperature, 30-35°C Ambient temperature 30-35°C Example 1 Example 2 Example 3 Example 4 Activator Ml 0 5 0 7.5 0 10 0 15 Biogas Ml/day 544 1656 600 2400 574 2980 560 4150 Rate of biogas Ml/h 22.6 69 25 100 23.8 124 23 173 Methane % 51 68 51 69 50 68 51 69 Carbon dioxide % 48 31 47 30 47 32 47 30 PH 7.1 6.6 7.1 6.9 7.1 6.6 7.1 6.8 Volatile Acids Acetate PPM 223 354 363 620 148 347 158 357 Propionate PPM 220 1028 335 971 255 1068 82 825 Butyrate PPM 99 205 145 166 45 240 32 41 Isobutyrate PPM 38 167 ND 283 ND 140 5 219 Valerate PPM 76 970 15 27 10 110 ND 193 Isovalerate PPM 52 140 ND 27 ND ND ND 133 Control digester (1.150 liter) was fed daily with 30 ml of gobar slurry containing 50 % (wet wt/v) gobar. Experimental digester (1.150 liter) was fed daily with 30 ml of gobar slurry containing 50 % (wet wt/v) gobar and activator. Data presented is the average of 30 days. Volatile acids (PPM) of gobar slurry : Acetate, 98; propionate, 304; butyrate, 52; valerate, 20 and isovalerate, 19. ND: Not detected. Table 2 : Production of biogas and volatile acid profile during the digestion at low temperatures. Ambient Temperature 12-15OC 10-12OC Period 1-15 days 16-30 days 31-45 days 46-60 days 1-15 days 16-30 days Activator Ml 0 3 0 3 0 3 0 3 0 3 0 3 Biogas Ml/day 107 535 147 511 170 540 172 528 160 385 150 350 Rate of biogas Ml/h 4.5 22.3 6.1 21.3 7.1 23.3 7.1 22 6.7 16 6.3 14.6 Methane % 50 63 49 65 54 70 55 71 54 70 54 71 Carbon dioxide % 48 36 48 31 45 26 43 26 43 24 40 23 PH 7.0 6.8 7.0 6.7 6.8 6.4 6.7 6.2 6.6 6.2 6.4 6.0 Volatile Acids Acetate PPM 182 283 120 136 54 830 45 750 82 489 105 560 Propionate PPM 261 1175 90 635 532 998 29 745 62 627 150 780 Butyrate PPM ND 52 18 87 25 51 12 346 18 668 26 816 Isobutyrate PPM ND 18 ND 156 ND ND ND 83 ND ND ND 15 Valerate PPM ND 101 14 165 ND 145 ND 28 ND 99 56 160 Isovalerate PPM ND 58 ND 67 ND ND ND ND ND ND ND 27 Control digester (1.150 liter) was fed daily with 30 ml of gobar slurry containing 50 % (wet wt/v) gobar. Experimental digester (1.150 liter) was fed daily with 30 ml gobar slurry containing 50 % (wet wt/v) gobar and 3 ml of activator. Data presented is the average of 15 days. ND: Not detected. Table 3 : Production of biogas and volatile acid profile during normalization of digester at 28-32°C. Normalization of digester 30 days Control Experimental Gobar slurry Activator Ml 0 0 Biogas Ml/day 649 690 Methane % 50 70 Carbondioxide % 45 27 PH 6.8 6.0 7.0 Volatile acids Acetate PPM 1885 1390 98 Propionate PPM 332 1181 304 Butyrate PPM 260 2710 52 Isobutyrate PPM ND 490 ND Valerate PPM 256 290 20 Isovalerate PPM ND 112 19 ND : Not detected Claims : We claim: 1. A process for the production of several folds more biogas with a higher calorific value at ambient temperatures (25-37°C) as well as at low temperatures (below 15°C) comprises the following steps of : a) stabilization of biogas digester by filling a slurry of gobar or of carbonaceous waste to a biogas digester volume and maintaining at ambient temperature ranging from 25°C to 37°C in an air tight condition; b) development of stabilized biogas digester and production of several folds more biogas at ambient temperature ranging from 25°C to 37°C by feeding a slurry of gobar containing ammonium carbonate, di-potassium hydrogen phosphate and water miscible organic solvents such as methanol; . c) production of biogas at low temperature, below 15°C, from the developed biogas digester by feeding a slurry of gobar with reduced quantities of ammonium carbonate, di-potassium hydrogen phosphate and methanol; d) normalization of the developed biogas digester at ambient temperature ranging from 28°C to 32°C by feeding a slurry of gobar. 2. A process according to claim 1 wherein said the slurry of gobar is a suspension of wet gobar in water in 1: 1 ratio (wet weight / volume). 3. A process according to claim 1 wherein said the slurry of gobar in step (a) is fed to an air tight biogas digester volume. 4. A process according to claim 1 wherein said the slurry of gobar is reacted as in step (a) for 10 to 30 days to develop anaerobic conditions or for the stabilization of biogas digester. 5. A process according to claim 4 wherein said the stabilization period is 10 days. 6. A process according to claim 1 wherein said temperature in step (a) for stabilization is 25°C to 37°C. 7. A process according to claim 6 wherein said temperature for stabilization is 30°C to 37°C. 8. A process according to claim 1 wherein said stabilized biogas digester in step (a) is fed one time per day with a slurry of gobar for the development of biogas digester to a hydraulic retention time of 30 days. 9. A process according to claim 1 wherein said biogas digester is fed one time daily as in claim 8 with a slurry of gobar containing varying concentrations of ammonium carbonate, 320 μ mol to 960 μ mol; di-potassium hydrogen phosphate, 15 μ mol to 45 μ mol and methanol, 60 m mol to 180 m mol for the development and production of several folds more biogas. 10.. A process according to claim 9 wherein said biogas digester in step (b) is fed daily with a slurry of gobar containing ammonium carbonate, 640 μ mol; di-potassium hydrogen phosphate, 30 u mol and methanol, 120 m mol at an ambient temperature. 11. A process according to claim 1 wherein said ambient temperature in step ( b) is 25°C to 37°C. 12. A process according to claim 11 wherein said temperature for the-production of several folds, 3 to 7 folds, more biogas from the developed biogas digester is 30°C to 35°C. 13. A process according to claim 12 wherein said a several folds more biogas is rich in methane content, 70 percent, indicates high calorific value. 14. A process according to claim 1.2 wherein said the effluent obtained in step (b) is rich in anaerobic bacteria and methane producing bacteria. 15. A process according to claim 1 wherein said temperature in step. (. c) is 10°C to 16. A process according to claim 15 wherein said biogas production occurs at a temperature of 12°C to 15°C. 17. A process according to claim 1 wherein said biogas digester in step ( c ) is fed one time per day with a slurry of gobar containing ammonium carbonate, 64 μ, mol to 320 p mol; di-potassium hydrogen phosphate, 3 p mol to 15 p mol and methanol, 12 p mol to 60 p mol for the production of more biogas at low temperature. 18. A process according to clairri 17 wherein said biogas digester is fed one time per day with a slurry of gobar containing ammonium carbonate, 192 p. mol;, di-potassium hydrogen phosphate, 9 p mol and methanol, 36 m mol for the production .of biogas at low temperatures, below 15°C. 19. A process according to claim 18 wherein said produced biogas is rich in methane content, 70 to 71 percent. 20. A process according to claim 18 wherein said the production of biogas is equivalent to the production of biogas at an ambient temperature, 30°C to 35°C, obtained by feeding a same quantity of slurry of gobar only. A process according to claim 1 wherein said normalization of biogas digester in step ( d) occurs at a temperature at 28°C to 32°C. 22. A process according to claim 1 wherein said a slurry of gobar is fed daily with a stepwise reduction in the concentrations of ammonioum carbonate, 320 μ mol to 0 p mol; di-potassium hydrogen phosphate, 15 p mol to 0 p mol and methanol,60 m mol to 0 m mol for the normalization of biogas digester. 23. A process according to claim 22 wherein said a slurry of gobar is fed one time per day without any supplementation. 24. A process according to claim 1 wherein said a production of biogas by the normalized biogas digester is higher than that of biogas digester without any treatment according to claim 1 as in steps a, b and c. 25. A process according to claim 1 wherein said effluent of normalized biogas digester contains a rich microflora of nonmethanogenic and methanogenic bacteria. 26. A process according to claim 1 wherein said gobar is a cattle dung or cattle manure and waste is animal manure or any other carbonaceous waste such as canteen waste, agriculture waste. 27. A process according to claim 26 wherein said manure or waste is fed to the biogas digester in a form of slurry containing between 8 percent to 10 percent of solids. 28. A process according to claim 1 wherein said waste contains biologically active bacteria include anaerobic microorganisms and methane producing bacteria which convert organic waste to acetate and carbon dioxide and then to methane and carbon .dioxide respectively. 29. A process according to claim 1 wherein said process is semicontinuous process. 30. A process according to claim 1 wherein said biogas is a gas produced from the group . consisting mainly of methane, carbon dioxide etc and mixtures thereof. 31. A process according to claim 1 wherein said the production of biogas in step (b) is several folds more than that of other procedures described for production of biogas at an ambient temperatures ranging from 25°C to 37°C. 32. A process according to claim 1 wherein said the production of biogas in step (c) is two folds to five folds more than that of other procedures described for production of biogas at low temperatures ranging from 15°C to 10°C. 33. A process according to claim 1 wherein said the biogas produced is rich in methane content at ambient temperatures ranging from 30°C to 37°C as well as at low temperatures, below 15°C than that of other procedures described for the production of biogas. Dated this 6th day of Feburary 2003 Signature of the Applicant: (V. S. Rao) Director Agharkar Research Institute, Pune FORM 2 THE PATENTS ACT, 1970 (39 Of 1970) COMPLETE SPECIFICATION (See sections 10 ) 1. Title of the invention 1. Procedure for the production of several folds more biogas with a higher calorific value at ambient temperatures (25-37°C) as well as at low temperatures (below 15°C). 2. Repeat the columns (a) to (c) if there are more than one applicant (a) 3. Agharkar Research Institute (b) 4. G.G. Agarkar Road, Pune-411 004, Maharashtra, India. (c)5. Nationality : Indian 3. Insert the name in full. The family or principal name in the beginning if the applicant is a natural person. 4. Insert the complete address including postal index number/ Code and State and /or country The following specification particularly, describes the nature of the invention and the manner in which it is to be Performed. 5. Insert the nationality Strike out in case of provisional Specification GARNTED 29/1/2004 ORIGINAL 162/MUMNP/20003 06/02/03 Procedure for the production of several folds more biogas with a higher calorific value at normal ambient temperatures (25-37°C) as well as at low temperatures (below 15°C) This invention relates to an improved process for obtaining several folds more biogas with a high alorific value at low temperatures (10-15°C) as well as at normal ambient temperatures 25-37°C). n the past a number of attempts have been described for obtaining biogas from cattle dung gobar) at low temperatures. At low temperatures growth of methanogens, methane-producing bacteria, is restricted and methane formation is slowed down. Similarly, activity and growth rate of other bacteria, which produce acetate, CO2 etc also, reduced at low temperature resulting in lecreased production of acetate and CO2. Methanogens are limited in their available substrates acetate and CO2). This narrows range of substrates that can support growth of methanogens. At ow temperatures, methane fermentations may continue slowly and possibly resulting in an nactivation of methane formation and stopped at low temperatures. Therefore in winter, where he temperature of biogas digesters reaches below 15°C, functioning of biogas digesters is everely affected. Ve have now found that biogas can be produced at low temperatures, 10-15°C, in a good yield several folds more) by a simple procedure using ordinary chemicals as activators along with gobar slurry. If a chemical, which activates growth of methanogens, is supplemented (provided) 0 active methanogens, methane formation gets activated and ultimately a dense culture of nethanogens (a cell-mass) is developed. Similarly ammonium carbonate, ammonia solution, mmonium chloride, diammonium phosphate like ammonium ion producing compounds can be used as a nitrogen source as methanogens utilize free NH4 and it also helps in maintaining pH. We have used ammonium carbonate because it is cheap and very easy to handle. Potassium (K) and PO4 (Phosphate) requirement is satisfied by di-potassium hydrogen phosphate (K2HPO4). Vitamins, trace minerals and other essential components required for the growth of bacteria are vailable from gobar. On this basis, an activator, an aqueous homogeneous mixture, is prepared vith the following composition (per ml of aqueous activator): ammonium carbonate; 64 Μ mol, ii-potassium hydrogen phosphate; 3 μ mol and methanol; 12 m mol. In object of the present investigation is to produce several folds more biogas by a commercial crocess, which will give good yields of biogas at low temperatures as well as at normal ambient smperatures also. Another object is to produce biogas at low temperature by a semicontineous irocess without the use of highly specialized and expensive equipments and chemicals. A still urther object is to produce biogas with a higher calorific value i.e. biogas containing higher per entage of methane. an carrying out the process of the present investigation, we have found that the use of essentially lomogeneous aqueous-methanolic solvents allows a greater degree of intimate contact between substrates and the microorganisms and thus produces higher yields of biogas. The solvents found. useful are those miscible with water such as methanol, which promotes growth of some methanogens. Also found desirable as an excess of ammonium carbonate, which prevents formation of clumps of methanogens or helps in disaggregation of methanogens resulting in increasing the permeability of the substrates into the cells of methanogens. The process of the present investigation can be carried out using practically any animal waste, agricultural waste, industrial waste, canteen waste etc in absence of oxygen and in presence of methanogens, however we prefer to use, the cattle dung (gobar) since it is readily available and is also a good source of methanogens. Cattle dung is used as a common substrate to run biogas plants in India. In India, gobar gas plants are popular for generating fuel for domestic purposes. For best results it is necessary to use fifty per cent gobar slurry prepared in water which gives about 9-10 per cent of total solids. While carrying out the present process, it is desirable to carry out the experiments at the ambient temperature between 25-37°C to stabilize the digester. Best results are obtained at a temperature of 30-35°C. Now the procedure will be more clearly described with reference to Figure of accompanying drawing wherein Figure shows the schematic diagram of a digester for the production of biogas. Referring to Figure, a sturdy container which acts as an anaerobic digester (1), is having an inlet pipe (2) for feeding gobar slurry. Other side of the sturdy container (1) has the outlet pipe (3) with a valve for taking out effluent, which is collected in effluent container (4). There is one more outlet pipe (5) at the top of the digester with a valve for connecting outlet for biogas collected in biogas collector (6). After the stabilization of the 1.150 L glass digester (Fig.l) containing 940 ml of gobar slurry is fed daily with 30 ml of fresh gobar slurry containing varying concentrations of ammonium carbonate (320-960 μ mol), di-potassium hydrogen phosphate (15-45 μ mol) and methanol (60-180 m mol). Best results are obtained when the feeding 30 ml of gobar slurry contains ammonium carbonate; 640 u. mol; di-potassium hydrogen phosphate;30 μ mol and methanol; 120 m mol . The yield of gobar gas is 3-7 fold higher than that of the control digester depending upon concentrations of components of activators. The biogas produced is rich in methane content as compared to that of control. The increase in volatile acids indicates that the activator also activates the growth of nonmethanogenic bacteria. The population of methanogens is also increased indicating an increase in the intensity of factor F420. Factor F420 takes part in methane formation and methane produced is directly proportional to concentration of F420. After development of biogas digester as above, it is maintained at ambient temperature, 12-15°C and activator with lower concentration is fed daily with 30 ml of gobar slurry containing about 10 per cent total solids. At a concentration of ammonium carbonate; 192 μ mol, di-potassium hydrogen phosphate; 9 μ mol and methanol; 36 m mol in the 30 ml of gobar slurry, the biogas produced is equivalent to the biogas formed by control at an ambient temperature, 30-35°C and it is rich in methane content indicating increase in calorific value of biogas. The effluent obtained will be rich in N:P:K as the added activator consists of ammonium carbonate and di-potassium hydrogen phosphate. The rate of biogas formation is constant. The volatile acids increased indicating the activator also activates the growth of nonmethanogenic bacteria and the increased concentration of volatile acids is not toxic to methanogens. The growth of methanogens as well as concentration of factor F420 is also maintained or increased. This is in sharp contrast to statements in the prior art regarding the biogas production by other processes herein before described and to our experience with these processes. The following examples illustrate in detail the production of biogas from cattle dung (gobar), at lower temperature (10-15°C) as well as at ambient temperatures (25-37°C), in high yields with higher calorific value by using chemicals to activate the process. The examples are by way of illustration and are not intended to be a limitation of the invention. The present investigation includes stabilization of digester, development of digester, production of biogas at low temperatures and normalization of digester at normal ambient temperature. Stabilization of a digester : In a 1.150-L glass digester (Fig.l), 940-ml of gobar slurry is kept in an anaerobic condition for 10 days at an ambient temperature (25-37°C). When a sufficient biogas is produced containing 45-50 per cent of methane, then it is confirmed that the digester is stabilized. Development of a digester : The stabilized digester is fed daily with 30 ml of gobar slurry along with varying concentrations of activator. When a biogas is produced with a constant rate containing 65-69 per cent of methane, then it is assumed that the digester is developed. Microscopic observations of effluent show several folds higher population of methanogens than that of control. Example 1 Two, 1.150 liter digesters (Fig.l) containing 940 ml of gobar slurry in each are stabilized at 30-35°C, which produced about 500 ml of biogas per day after feeding 30 ml of gobar slurry every day. The biogas contains about 51 per cent methane and 48 per cent CO2. Out of these two digesters one is fed with 30 ml of gobar slurry per day and maintained as a control. Another digester is fed daily with 30 ml of gobar slurry along with activator (5 ml) containing ammonium carbonate; 320 μ mol, di-potassium hydrogen phosphate; 15 μ mol and methanol; 60 m mol. Biogas produced, rate of biogas production, analysis of biogas, pH and composition of volatile acid of effluent slurry are determined. An average data of 30 days is presented in Table 1. A 3-fold more biogas with a high calorific value accounting 68 per cent methane is produced by the activator. supplemented digester as compare to that of control. A dense population of methanogens was developed in the experimental digester. Methanogens in the experimental digester showed bright epifluorescence under ultraviolet light when observed under microscope and cells of clump forming methanogens are disaggregated. Example 2 An experiment is carried out as in Example 1, and a 30 ml of gobar slurry containing activator (7.5 ml) with concentrations: ammonium carbonate; 480 u. mol, di-potassium hydrogen phosphate;22.5 μ mol and methanol;90 m mol is fed daily to the experimental digester for 30 days. The results (Table 1) indicate that there is a 4 -fold increase in biogas with 69 per cent of methane as compare to that of control. The microscopic observations showed that the population of methanogens was higher than that of control. Example 3 An experiment is conducted as in Example 1. An activator (10 ml) with the following concentrations : ammonium carbonate; 640 μ mol, di-potassium hydrogen phosphate; 30 μ mol and methanol; 120 m mol in 30 ml of gobar. slurry is fed to the experimental digester. The measurements indicate that there is a 5-fold increase in biogas as compared to that of control. The biogas produced in the experimental digester contains 68 per cent of methane (Table 1). The population of methanogens is more than the control (Table 4) and they showed bright epifluorescence under ultraviolet light when observed under the microscope. Example 4 An experiment is conducted as above. The gobar slurry, 30 ml, is fed with activator (15 ml) with the following concentrations: ammonium carbonate; 960 u. mol, di-potassium hydrogen phosphate; 45 Μ mol and methanol; 180 m mol. The measurements show that there is about 7-fold increase in biogas with 69 per cent of methane as compared to that of control digester (Table 1). A very dense population of methanogens was developed and showed very bright epifluorescence under ultraviolet light. Production of biogas at low temperature: The developed digesters, as above are shifted to low temperatures (12-15°C) and the biogas formation is studied. Example 5 In view to study the biogas formation at low temperature (12-15°C), the digesters in Example 3 are shifted to a cold room, where the temperature is maintained at 12-15°C. For the control digester, 30 ml of gobar slurry is fed daily and for the experimental digester, 30 ml of gobar slurry along with activator (3 ml) having concentrations: ammonium carbonate; 192 u. mol, di-potassium hydrogen phosphate; 9 μ mol and methanol; 36 m mol is fed daily. With this treatment a 5-fold increase in biogas with 63-68 per cent of methane is obtained as compared to that of control (Table 2) and it is almost equivalent to the biogas produced at 30-35 °C by the control digester (Table 1). The experiment is conducted for 60 days. During the period, the rate of biogas formation, methane per centage, yield of biogas is almost constant or increased. There is an increase in volatile acids in the effluent of experimental digester, however the higher concentration of volatile acids is not toxic to methanogens. The overall population of methanogens is slightly decreased (Table 4). The cells of clump-forming methanogens (Methanosarcina) are separated or disaggregated and showed bright epifluorescence under ultraviolet light. Thus, this semicontinuous process illustrates a further advantage of obtaining more biogas at low temperatures (below 15°C). Example 6 The digesters maintained at 12-15°C in Example 5, are then maintained at 10-12°C in a cold room and biogas formation is studied for 30 days. The experimental digester was fed daily with 30 ml gobar slurry containing 3 ml of activator. In both cases, biogas formation was severely affected. Eventhen the biogas produced in the experimental digester is two folds higher than that of the control. The methane percentage in the biogas produced by experimental digester is 69-70, whereas in the control it is 54-55 percent (Table 2). At 10-12°C also methanogens show bright epifluorescence. However the activity of methanogens is decreased resulting in decrease in the intensity of F420 (Table 4). Normalization of digesters : After the experiments at low temperature, both digesters are shifted to normal ambient temperature (28-32°C), in view to study their functioning at normal ambient temperature. As the bacteria from both digesters are in stress conditions, they took some time for adaptation at normal ambient temperature. Example 7 After studying the digestion at low temperature, digesters in Example 6 are maintained at ambient temperature 28-32°C to study their functioning at normal ambient temperature. In initial 4-5 days the rate of methane formation is slow. However after that the rate of methane formation increased and both digesters produced methane with a constant rate (Table 3). The experimental digester produced more methane as it contains higher population of methanogens (Table 4). Thus after stress conditions also one can get higher biogas than that of control as the activator helps in producing higher population of methanogens. However, biogas decreases with a slow rate as experimental digester is fed with 30 ml of gobar slurry every day along with decreasing quantities of an activator as expected. And after some days the experimental digester was fed with only 30 ml gobar slurry as a normal feeding. METHODOLOGY Stabilization of digester: A digestion of gobar slurry was carried out in 1.150-L fixed dome glass digester (Fig.l) with a working volume of 940 ml. Gobar was diluted 1:1 (wet wt/v) with water and kept in anaerobic condition for 10 days at an ambient temperature (27-32°C). When a sufficient biogas was produced containing 45-50 percent methane then feeding was done at every 24 h for 30 days hydraulic retention time (HRT) using two digesters for the same HRT. Digestion was carried out at normal ambient temperature (25-35°C). Development of digesters: One of these two stabilized digesters is fed daily with 30 ml of gobar slurry only and maintained as a control. Another digester was fed daily with varying concentrations of activator along with 30 ml of gobar slurry and maintained as an experimental digester. Development of digesters was carried out at normal ambient temperature and at 30 days HRT. When the biogas production of experimental digester reaches several fold higher than that of control and contains 65-69 per cent of methane then it is assumed that the digester is developed. Biogas production at low temperature: After the development of digesters, digestion was carried out at 12-15°C in an environmental chamber or in a cold room. Feeding of 30 ml of gobar slurry was done every 24 h to the control digester for 60 days. Similarly, experimental digester was fed daily with 30 ml of gobar slurry containing reduced concentrations of activators for 60 days. After studying the biomethanation at 12-15°C, biogas production was also carried out at 10-12°C. Normalization of digesters: After the digestion at low temperature, digestion was carried out at normal ambient temperature by feeding 30 ml of gobar slurry at every 24 h to the control digester at 30 days HRT and to the experimental digester 30 ml gobar slurry was fed along with decreasing quantities of an activator. Biogas production was compared. ANALYSIS Biogas production was monitored daily by displacement of water. Volatile acids, pH of the slurry and methane content in the biogas were measured at weekly intervals. Microbial counts and intensity of factor F420 in the effluent slurry were also monitored at weekly intervals. Gas analysis: The biogas produced was analyzed for its methane content by using a gas chromatograph (Chemito 3800, Mumbai), equipped with a thermal conductivity detector (TCD) and S.S. column (8' x 1/8") packed with Porapak Q (mesh No. 80/100). Hydrogen (40 ml/min) was used as a carrier gas (Ranade et al 1987). Volatile acids analysis: Volatile acids were analyzed by using a gas chromatograph (Chemito 8510, Mumbai), equipped with flame ionization detector (FID) and S.S. column (8' x 1/8") packed with 10 per cent FFAP on Chemosorb W (HP) 80/100. Nitrogen (40 ml/min) was used as a carrier gas. The temperature of oven, injector and of detector were set to 150,190 and 200°C respectively (Yeole et al 1989). Microbial counts: Methanogens and total bacterial counts were taken by microscopic observation under UV-light and with the bright-field microscope respectively using Neubauer chamber. Active methanogens show bright epifluorescence under UV-light. Nonmethanogens were calculated by subtracting counts of methanogens (fluorescent cells) from counts of total bacteria. Factor F420: Intensity of Factor F42o was measured fluorometrically (Shimadzu Spectrofluorophotometer RF-5301 PC) from alkaline extracts of effluent gobar slurry at Ex-nm 425 and Em-nm 472. To a 9-ml of effluent gobar slurry, 1-ml of 1 N KOH was added and mixed. The extract was centrifuged after 2 h and supernatant was used for fluorometric measurements (Delafontaine et al 1979). Preparation of an Activator: A weighed quantity (2.5 g) of ammonium carbonate and 250 mg of di-potassium hydrogen phosphate was dissolved in a homogeneous mixture of water and methanol (250:250 ml). This homogeneous mixture is called as an Activator. References Cited in the file of this patent Ranade,D.R.,Yeole,T.Y. and Godbole,S.H., (1987),Production of biogas from market waste. Biomass,13, 147-153. Yeole,T.Y.,Ranade,D.R. and Gadre,R.V. (1989),Biogas from liquid waste arising in liver and beef extract production. RERIC International Energy Journal, 11, 35-39. Delafontaine,M.J., Naveau,H.P. and Nyns E.J. (1979), Fluorimetric monitoring of methanogenesis in anaerobic digesters, Biotechnology Letters, 1, 71-74. Table 1 : Production of biogas and volatile acid profile during the development of digesters at an ambient temperature, 30-35°C Ambient temperature 30-35°C Example 1 Example 2 Example 3 Example 4 Activator Ml 0 5 0 7.5 0 10 0 15 Biogas Ml/day 544 1656 600 2400 574 2980 560 4150 Rate of biogas Ml/h 22.6 69 25 100 23.8 124 23 173 Methane % 51 68 51 69 50 68 51 69 Carbon dioxide % 48 31 47 30 47 32 47 30 PH 7.1 6.6 7.1 6.9 7.1 6.6 7.1 6.8 Volatile Acids Acetate PPM 223 354 363 620 148 347 158 357 Propionate PPM 220 1028 335 971 255 1068 82 825 Butyrate PPM 99 205 145 166 45 240 32 41 Isobutyrate PPM 38 167 ND 283 ND 140 5 219 Valerate PPM 76 970 15 27 10 110 ND 193 Isovalerate PPM 52 140 ND 27 ND ND ND 133 Control digester (1.150 liter) was fed daily with 30 ml of gobar slurry containing 50 % (wet wt/v) gobar. Experimental digester (1.150 liter) was fed daily with 30 ml of gobar slurry containing 50 % (wet wt/v) gobar and activator. Data presented is the average of 30 days. Volatile acids (PPM) of gobar slurry : Acetate, 98; propionate, 304; butyrate, 52; valerate, 20 and isovalerate, 19. ND: Not detected. Table 2 : Production of biogas and volatile acid profile during the digestion at low temperatures. Ambient Temperature 12-15OC 10-12OC Period 1-15 days 16-30 days 31-45 days 46-60 days 1-15 days 16-30 days Activator Ml 0 3 0 3 0 3 0 3 0 3 0 3 Biogas Ml/day 107 535 147 511 170 540 172 528 160 385 150 350 Rate of biogas Ml/h 4.5 22.3 6.1 21.3 7.1 23.3 7.1 22 6.7 16 6.3 14.6 Methane % 50 63 49 65 54 70 55 71 54 70 54 71 Carbon dioxide % 48 36 48 31 45 26 43 26 43 24 40 23 PH 7.0 6.8 7.0 6.7 6.8 6.4 6.7 6.2 6.6 6.2 6.4 6.0 Volatile Acids Acetate PPM 182 283 120 136 54 830 45 750 82 489 105 560 Propionate PPM 261 1175 90 635 532 998 29 745 62 627 150 780 Butyrate PPM ND 52 18 87 25 51 12 346 18 668 26 816 Isobutyrate PPM ND 18 ND 156 ND ND ND 83 ND ND ND 15 Valerate PPM ND 101 14 165 ND 145 ND 28 ND 99 56 160 Isovalerate PPM ND 58 ND 67 ND ND ND ND ND ND ND 27 Control digester (1.150 liter) was fed daily with 30 ml of gobar slurry containing 50 % (wet wt/v) gobar. Experimental digester (1.150 liter) was fed daily with 30 ml gobar slurry containing 50 % (wet wt/v) gobar and 3 ml of activator. Data presented is the average of 15 days. ND: Not detected. Table 3 : Production of biogas and volatile acid profile during normalization of digester at 28-32°C. Normalization of digester 30 days Control Experimental Gobar slurry Activator Ml 0 0 Biogas Ml/day 649 690 Methane % 50 70 Carbondioxide % 45 27 PH 6.8 6.0 7.0 Volatile acids Acetate PPM 1885 1390 98 Propionate PPM 332 1181 304 Butyrate PPM 260 2710 52 Isobutyrate PPM ND 490 ND Valerate PPM 256 290 20 Isovalerate PPM ND 112 19 ND : Not detected Claims : We claim: 1. A process for the production of several folds more biogas with a higher calorific value at ambient temperatures (25-37°C) as well as at low temperatures (below 15°C) comprises the following steps of : a) stabilization of biogas digester by filling a slurry of gobar or of carbonaceous waste to a biogas digester volume and maintaining at ambient temperature ranging from 25°C to 37°C in an air tight condition; b) development of stabilized biogas digester and production of several folds more biogas at ambient temperature ranging from 25°C to 37°C by feeding a slurry of gobar containing ammonium carbonate, di-potassium hydrogen phosphate and water miscible organic solvents such as methanol; . c) production of biogas at low temperature, below 15°C, from the developed biogas digester by feeding a slurry of gobar with reduced quantities of ammonium carbonate, di-potassium hydrogen phosphate and methanol; d) normalization of the developed biogas digester at ambient temperature ranging from 28°C to 32°C by feeding a slurry of gobar. 2. A process according to claim 1 wherein said the slurry of gobar is a suspension of wet gobar in water in 1: 1 ratio (wet weight / volume). 3. A process according to claim 1 wherein said the slurry of gobar in step (a) is fed to an air tight biogas digester volume. 4. A process according to claim 1 wherein said the slurry of gobar is reacted as in step (a) for 10 to 30 days to develop anaerobic conditions or for the stabilization of biogas digester. 5. A process according to claim 4 wherein said the stabilization period is 10 days. 6. A process according to claim 1 wherein said temperature in step (a) for stabilization is 25°C to 37°C. 7. A process according to claim 6 wherein said temperature for stabilization is 30°C to 37°C. 8. A process according to claim 1 wherein said stabilized biogas digester in step (a) is fed one time per day with a slurry of gobar for the development of biogas digester to a hydraulic retention time of 30 days. 9. A process according to claim 1 wherein said biogas digester is fed one time daily as in claim 8 with a slurry of gobar containing varying concentrations of ammonium carbonate, 320 μ mol to 960 μ mol; di-potassium hydrogen phosphate, 15 μ mol to 45 μ mol and methanol, 60 m mol to 180 m mol for the development and production of several folds more biogas. 10.. A process according to claim 9 wherein said biogas digester in step (b) is fed daily with a slurry of gobar containing ammonium carbonate, 640 μ mol; di-potassium hydrogen phosphate, 30 u mol and methanol, 120 m mol at an ambient temperature. 11. A process according to claim 1 wherein said ambient temperature in step ( b) is 25°C to 37°C. 12. A process according to claim 11 wherein said temperature for the-production of several folds, 3 to 7 folds, more biogas from the developed biogas digester is 30°C to 35°C. 13. A process according to claim 12 wherein said a several folds more biogas is rich in methane content, 70 percent, indicates high calorific value. 14. A process according to claim 1.2 wherein said the effluent obtained in step (b) is rich in anaerobic bacteria and methane producing bacteria. 15. A process according to claim 1 wherein said temperature in step. (. c) is 10°C to 16. A process according to claim 15 wherein said biogas production occurs at a temperature of 12°C to 15°C. 17. A process according to claim 1 wherein said biogas digester in step ( c ) is fed one time per day with a slurry of gobar containing ammonium carbonate, 64 μ, mol to 320 p mol; di-potassium hydrogen phosphate, 3 p mol to 15 p mol and methanol, 12 p mol to 60 p mol for the production of more biogas at low temperature. 18. A process according to clairri 17 wherein said biogas digester is fed one time per day with a slurry of gobar containing ammonium carbonate, 192 p. mol;, di-potassium hydrogen phosphate, 9 p mol and methanol, 36 m mol for the production .of biogas at low temperatures, below 15°C. 19. A process according to claim 18 wherein said produced biogas is rich in methane content, 70 to 71 percent. 20. A process according to claim 18 wherein said the production of biogas is equivalent to the production of biogas at an ambient temperature, 30°C to 35°C, obtained by feeding a same quantity of slurry of gobar only. A process according to claim 1 wherein said normalization of biogas digester in step ( d) occurs at a temperature at 28°C to 32°C. 22. A process according to claim 1 wherein said a slurry of gobar is fed daily with a stepwise reduction in the concentrations of ammonioum carbonate, 320 μ mol to 0 p mol; di-potassium hydrogen phosphate, 15 p mol to 0 p mol and methanol,60 m mol to 0 m mol for the normalization of biogas digester. 23. A process according to claim 22 wherein said a slurry of gobar is fed one time per day without any supplementation. 24. A process according to claim 1 wherein said a production of biogas by the normalized biogas digester is higher than that of biogas digester without any treatment according to claim 1 as in steps a, b and c. 25. A process according to claim 1 wherein said effluent of normalized biogas digester contains a rich microflora of nonmethanogenic and methanogenic bacteria. 26. A process according to claim 1 wherein said gobar is a cattle dung or cattle manure and waste is animal manure or any other carbonaceous waste such as canteen waste, agriculture waste. 27. A process according to claim 26 wherein said manure or waste is fed to the biogas digester in a form of slurry containing between 8 percent to 10 percent of solids. 28. A process according to claim 1 wherein said waste contains biologically active bacteria include anaerobic microorganisms and methane producing bacteria which convert organic waste to acetate and carbon dioxide and then to methane and carbon .dioxide respectively. 29. A process according to claim 1 wherein said process is semicontinuous process. 30. A process according to claim 1 wherein said biogas is a gas produced from the group . consisting mainly of methane, carbon dioxide etc and mixtures thereof. 31. A process according to claim 1 wherein said the production of biogas in step (b) is several folds more than that of other procedures described for production of biogas at an ambient temperatures ranging from 25°C to 37°C. 32. A process according to claim 1 wherein said the production of biogas in step (c) is two folds to five folds more than that of other procedures described for production of biogas at low temperatures ranging from 15°C to 10°C. 33. A process according to claim 1 wherein said the biogas produced is rich in methane content at ambient temperatures ranging from 30°C to 37°C as well as at low temperatures, below 15°C than that of other procedures described for the production of biogas. Dated this 6th day of Feburary 2003 Signature of the Applicant: (V. S. Rao) Director Agharkar Research Institute, Pune

Full Text

FORM 2
THE PATENTS ACT, 1970
(39 Of 1970)
COMPLETE SPECIFICATION
(See sections 10 )

1. Title of the invention

1. Procedure for the production of several folds more biogas with a higher calorific value at ambient temperatures (25-37°C) as well as at low temperatures (below 15°C).

2. Repeat the columns (a) to (c) if there are more than one applicant

(a) 3. Agharkar Research Institute
(b) 4. G.G. Agarkar Road,
Pune-411 004, Maharashtra, India.

(c)5. Nationality : Indian
3. Insert the name in full. The family or principal name in the beginning if the applicant is a natural person.

4. Insert the complete address including postal index number/ Code and State and /or country

The following specification particularly, describes the nature of the invention and the manner in which it is to be Performed.

5. Insert the nationality

Strike out in case of provisional Specification

GARNTED
29/1/2004

ORIGINAL
162/MUMNP/20003
06/02/03

Procedure for the production of several folds more biogas with a higher calorific value at normal ambient temperatures (25-37°C) as well as at low
temperatures (below 15°C)
This invention relates to an improved process for obtaining several folds more biogas with a high alorific value at low temperatures (10-15°C) as well as at normal ambient temperatures 25-37°C).
n the past a number of attempts have been described for obtaining biogas from cattle dung gobar) at low temperatures. At low temperatures growth of methanogens, methane-producing bacteria, is restricted and methane formation is slowed down. Similarly, activity and growth rate of other bacteria, which produce acetate, CO2 etc also, reduced at low temperature resulting in lecreased production of acetate and CO2. Methanogens are limited in their available substrates acetate and CO2). This narrows range of substrates that can support growth of methanogens. At ow temperatures, methane fermentations may continue slowly and possibly resulting in an nactivation of methane formation and stopped at low temperatures. Therefore in winter, where he temperature of biogas digesters reaches below 15°C, functioning of biogas digesters is everely affected.
Ve have now found that biogas can be produced at low temperatures, 10-15°C, in a good yield several folds more) by a simple procedure using ordinary chemicals as activators along with gobar slurry. If a chemical, which activates growth of methanogens, is supplemented (provided) 0 active methanogens, methane formation gets activated and ultimately a dense culture of nethanogens (a cell-mass) is developed. Similarly ammonium carbonate, ammonia solution, mmonium chloride, diammonium phosphate like ammonium ion producing compounds can be used as a nitrogen source as methanogens utilize free NH4 and it also helps in maintaining pH. We have used ammonium carbonate because it is cheap and very easy to handle. Potassium (K) and PO4 (Phosphate) requirement is satisfied by di-potassium hydrogen phosphate (K2HPO4). Vitamins, trace minerals and other essential components required for the growth of bacteria are vailable from gobar. On this basis, an activator, an aqueous homogeneous mixture, is prepared vith the following composition (per ml of aqueous activator): ammonium carbonate; 64 Μ mol, ii-potassium hydrogen phosphate; 3 μ mol and methanol; 12 m mol.
In object of the present investigation is to produce several folds more biogas by a commercial crocess, which will give good yields of biogas at low temperatures as well as at normal ambient smperatures also. Another object is to produce biogas at low temperature by a semicontineous irocess without the use of highly specialized and expensive equipments and chemicals. A still urther object is to produce biogas with a higher calorific value i.e. biogas containing higher per entage of methane.
an carrying out the process of the present investigation, we have found that the use of essentially
lomogeneous aqueous-methanolic solvents allows a greater degree of intimate contact between
substrates and the microorganisms and thus produces higher yields of biogas. The solvents found.
useful are those miscible with water such as methanol, which promotes growth of some
methanogens. Also found desirable as an excess of ammonium carbonate, which prevents

formation of clumps of methanogens or helps in disaggregation of methanogens resulting in increasing the permeability of the substrates into the cells of methanogens.
The process of the present investigation can be carried out using practically any animal waste, agricultural waste, industrial waste, canteen waste etc in absence of oxygen and in presence of methanogens, however we prefer to use, the cattle dung (gobar) since it is readily available and is also a good source of methanogens. Cattle dung is used as a common substrate to run biogas plants in India. In India, gobar gas plants are popular for generating fuel for domestic purposes. For best results it is necessary to use fifty per cent gobar slurry prepared in water which gives about 9-10 per cent of total solids.
While carrying out the present process, it is desirable to carry out the experiments at the ambient temperature between 25-37°C to stabilize the digester. Best results are obtained at a temperature of 30-35°C. Now the procedure will be more clearly described with reference to Figure of accompanying drawing wherein Figure shows the schematic diagram of a digester for the production of biogas. Referring to Figure, a sturdy container which acts as an anaerobic digester (1), is having an inlet pipe (2) for feeding gobar slurry. Other side of the sturdy container (1) has the outlet pipe (3) with a valve for taking out effluent, which is collected in effluent container (4). There is one more outlet pipe (5) at the top of the digester with a valve for connecting outlet for biogas collected in biogas collector (6). After the stabilization of the 1.150 L glass digester (Fig.l) containing 940 ml of gobar slurry is fed daily with 30 ml of fresh gobar slurry containing varying concentrations of ammonium carbonate (320-960 μ mol), di-potassium hydrogen phosphate (15-45 μ mol) and methanol (60-180 m mol). Best results are obtained when the feeding 30 ml of gobar slurry contains ammonium carbonate; 640 u. mol; di-potassium hydrogen phosphate;30 μ mol and methanol; 120 m mol . The yield of gobar gas is 3-7 fold higher than that of the control digester depending upon concentrations of components of activators. The biogas produced is rich in methane content as compared to that of control. The increase in volatile acids indicates that the activator also activates the growth of nonmethanogenic bacteria. The population of methanogens is also increased indicating an increase in the intensity of factor F420. Factor F420 takes part in methane formation and methane produced is directly proportional to concentration of F420.
After development of biogas digester as above, it is maintained at ambient temperature, 12-15°C and activator with lower concentration is fed daily with 30 ml of gobar slurry containing about 10 per cent total solids. At a concentration of ammonium carbonate; 192 μ mol, di-potassium hydrogen phosphate; 9 μ mol and methanol; 36 m mol in the 30 ml of gobar slurry, the biogas produced is equivalent to the biogas formed by control at an ambient temperature, 30-35°C and it is rich in methane content indicating increase in calorific value of biogas. The effluent obtained will be rich in N:P:K as the added activator consists of ammonium carbonate and di-potassium hydrogen phosphate. The rate of biogas formation is constant. The volatile acids increased indicating the activator also activates the growth of nonmethanogenic bacteria and the increased concentration of volatile acids is not toxic to methanogens. The growth of methanogens as well as concentration of factor F420 is also maintained or increased. This is in sharp contrast to statements in the prior art regarding the biogas production by other processes herein before described and to our experience with these processes.

The following examples illustrate in detail the production of biogas from cattle dung (gobar), at lower temperature (10-15°C) as well as at ambient temperatures (25-37°C), in high yields with higher calorific value by using chemicals to activate the process. The examples are by way of illustration and are not intended to be a limitation of the invention. The present investigation includes stabilization of digester, development of digester, production of biogas at low temperatures and normalization of digester at normal ambient temperature.
Stabilization of a digester : In a 1.150-L glass digester (Fig.l), 940-ml of gobar slurry is kept in an anaerobic condition for 10 days at an ambient temperature (25-37°C). When a sufficient biogas is produced containing 45-50 per cent of methane, then it is confirmed that the digester is stabilized.
Development of a digester : The stabilized digester is fed daily with 30 ml of gobar slurry along with varying concentrations of activator. When a biogas is produced with a constant rate containing 65-69 per cent of methane, then it is assumed that the digester is developed. Microscopic observations of effluent show several folds higher population of methanogens than that of control.
Example 1
Two, 1.150 liter digesters (Fig.l) containing 940 ml of gobar slurry in each are stabilized at 30-35°C, which produced about 500 ml of biogas per day after feeding 30 ml of gobar slurry every day. The biogas contains about 51 per cent methane and 48 per cent CO2. Out of these two digesters one is fed with 30 ml of gobar slurry per day and maintained as a control. Another digester is fed daily with 30 ml of gobar slurry along with activator (5 ml) containing ammonium carbonate; 320 μ mol, di-potassium hydrogen phosphate; 15 μ mol and methanol; 60 m mol. Biogas produced, rate of biogas production, analysis of biogas, pH and composition of volatile acid of effluent slurry are determined. An average data of 30 days is presented in Table 1. A 3-fold more biogas with a high calorific value accounting 68 per cent methane is produced by the activator. supplemented digester as compare to that of control. A dense population of methanogens was developed in the experimental digester. Methanogens in the experimental digester showed bright epifluorescence under ultraviolet light when observed under microscope and cells of clump forming methanogens are disaggregated.
Example 2
An experiment is carried out as in Example 1, and a 30 ml of gobar slurry containing activator (7.5 ml) with concentrations: ammonium carbonate; 480 u. mol, di-potassium hydrogen phosphate;22.5 μ mol and methanol;90 m mol is fed daily to the experimental digester for 30 days. The results (Table 1) indicate that there is a 4 -fold increase in biogas with 69 per cent of methane as compare to that of control. The microscopic observations showed that the population of methanogens was higher than that of control.

Example 3
An experiment is conducted as in Example 1. An activator (10 ml) with the following concentrations : ammonium carbonate; 640 μ mol, di-potassium hydrogen phosphate; 30 μ mol and methanol; 120 m mol in 30 ml of gobar. slurry is fed to the experimental digester. The measurements indicate that there is a 5-fold increase in biogas as compared to that of control. The biogas produced in the experimental digester contains 68 per cent of methane (Table 1). The population of methanogens is more than the control (Table 4) and they showed bright epifluorescence under ultraviolet light when observed under the microscope.
Example 4
An experiment is conducted as above. The gobar slurry, 30 ml, is fed with activator (15 ml) with the following concentrations: ammonium carbonate; 960 u. mol, di-potassium hydrogen phosphate; 45 Μ mol and methanol; 180 m mol. The measurements show that there is about 7-fold increase in biogas with 69 per cent of methane as compared to that of control digester (Table 1). A very dense population of methanogens was developed and showed very bright epifluorescence under ultraviolet light.
Production of biogas at low temperature: The developed digesters, as above are shifted to low temperatures (12-15°C) and the biogas formation is studied.
Example 5
In view to study the biogas formation at low temperature (12-15°C), the digesters in Example 3 are shifted to a cold room, where the temperature is maintained at 12-15°C. For the control digester, 30 ml of gobar slurry is fed daily and for the experimental digester, 30 ml of gobar slurry along with activator (3 ml) having concentrations: ammonium carbonate; 192 u. mol, di-potassium hydrogen phosphate; 9 μ mol and methanol; 36 m mol is fed daily. With this treatment a 5-fold increase in biogas with 63-68 per cent of methane is obtained as compared to that of control (Table 2) and it is almost equivalent to the biogas produced at 30-35 °C by the control digester (Table 1). The experiment is conducted for 60 days. During the period, the rate of biogas formation, methane per centage, yield of biogas is almost constant or increased. There is an increase in volatile acids in the effluent of experimental digester, however the higher concentration of volatile acids is not toxic to methanogens. The overall population of methanogens is slightly decreased (Table 4). The cells of clump-forming methanogens (Methanosarcina) are separated or disaggregated and showed bright epifluorescence under ultraviolet light. Thus, this semicontinuous process illustrates a further advantage of obtaining more biogas at low temperatures (below 15°C).
Example 6
The digesters maintained at 12-15°C in Example 5, are then maintained at 10-12°C in a cold room and biogas formation is studied for 30 days. The experimental digester was fed daily with 30 ml gobar slurry containing 3 ml of activator. In both cases, biogas formation was severely affected. Eventhen the biogas produced in the experimental digester is two folds higher than that

of the control. The methane percentage in the biogas produced by experimental digester is 69-70, whereas in the control it is 54-55 percent (Table 2). At 10-12°C also methanogens show bright epifluorescence. However the activity of methanogens is decreased resulting in decrease in the intensity of F420 (Table 4).
Normalization of digesters :
After the experiments at low temperature, both digesters are shifted to normal ambient temperature (28-32°C), in view to study their functioning at normal ambient temperature. As the bacteria from both digesters are in stress conditions, they took some time for adaptation at normal ambient temperature.
Example 7
After studying the digestion at low temperature, digesters in Example 6 are maintained at ambient temperature 28-32°C to study their functioning at normal ambient temperature. In initial 4-5 days the rate of methane formation is slow. However after that the rate of methane formation increased and both digesters produced methane with a constant rate (Table 3). The experimental digester produced more methane as it contains higher population of methanogens (Table 4). Thus after stress conditions also one can get higher biogas than that of control as the activator helps in producing higher population of methanogens. However, biogas decreases with a slow rate as experimental digester is fed with 30 ml of gobar slurry every day along with decreasing quantities of an activator as expected. And after some days the experimental digester was fed with only 30 ml gobar slurry as a normal feeding.
METHODOLOGY
Stabilization of digester: A digestion of gobar slurry was carried out in 1.150-L fixed dome glass digester (Fig.l) with a working volume of 940 ml. Gobar was diluted 1:1 (wet wt/v) with water and kept in anaerobic condition for 10 days at an ambient temperature (27-32°C). When a sufficient biogas was produced containing 45-50 percent methane then feeding was done at every 24 h for 30 days hydraulic retention time (HRT) using two digesters for the same HRT. Digestion was carried out at normal ambient temperature (25-35°C).
Development of digesters: One of these two stabilized digesters is fed daily with 30 ml of gobar slurry only and maintained as a control. Another digester was fed daily with varying concentrations of activator along with 30 ml of gobar slurry and maintained as an experimental digester. Development of digesters was carried out at normal ambient temperature and at 30 days HRT. When the biogas production of experimental digester reaches several fold higher than that of control and contains 65-69 per cent of methane then it is assumed that the digester is developed.
Biogas production at low temperature: After the development of digesters, digestion was carried out at 12-15°C in an environmental chamber or in a cold room. Feeding of 30 ml of gobar slurry was done every 24 h to the control digester for 60 days. Similarly, experimental digester was fed daily with 30 ml of gobar slurry containing reduced concentrations of activators for 60

days. After studying the biomethanation at 12-15°C, biogas production was also carried out at 10-12°C.
Normalization of digesters: After the digestion at low temperature, digestion was carried out at normal ambient temperature by feeding 30 ml of gobar slurry at every 24 h to the control digester at 30 days HRT and to the experimental digester 30 ml gobar slurry was fed along with decreasing quantities of an activator. Biogas production was compared.
ANALYSIS
Biogas production was monitored daily by displacement of water. Volatile acids, pH of the slurry and methane content in the biogas were measured at weekly intervals. Microbial counts and intensity of factor F420 in the effluent slurry were also monitored at weekly intervals.
Gas analysis: The biogas produced was analyzed for its methane content by using a gas chromatograph (Chemito 3800, Mumbai), equipped with a thermal conductivity detector (TCD) and S.S. column (8' x 1/8") packed with Porapak Q (mesh No. 80/100). Hydrogen (40 ml/min) was used as a carrier gas (Ranade et al 1987).
Volatile acids analysis: Volatile acids were analyzed by using a gas chromatograph (Chemito 8510, Mumbai), equipped with flame ionization detector (FID) and S.S. column (8' x 1/8") packed with 10 per cent FFAP on Chemosorb W (HP) 80/100. Nitrogen (40 ml/min) was used as a carrier gas. The temperature of oven, injector and of detector were set to 150,190 and 200°C respectively (Yeole et al 1989).
Microbial counts: Methanogens and total bacterial counts were taken by microscopic observation under UV-light and with the bright-field microscope respectively using Neubauer chamber. Active methanogens show bright epifluorescence under UV-light. Nonmethanogens were calculated by subtracting counts of methanogens (fluorescent cells) from counts of total bacteria.
Factor F420: Intensity of Factor F42o was measured fluorometrically (Shimadzu Spectrofluorophotometer RF-5301 PC) from alkaline extracts of effluent gobar slurry at Ex-nm 425 and Em-nm 472. To a 9-ml of effluent gobar slurry, 1-ml of 1 N KOH was added and mixed. The extract was centrifuged after 2 h and supernatant was used for fluorometric measurements (Delafontaine et al 1979).
Preparation of an Activator: A weighed quantity (2.5 g) of ammonium carbonate and 250 mg of di-potassium hydrogen phosphate was dissolved in a homogeneous mixture of water and methanol (250:250 ml). This homogeneous mixture is called as an Activator.
References Cited in the file of this patent
Ranade,D.R.,Yeole,T.Y. and Godbole,S.H., (1987),Production of biogas from market waste.
Biomass,13, 147-153.
Yeole,T.Y.,Ranade,D.R. and Gadre,R.V. (1989),Biogas from liquid waste arising in liver and
beef extract production. RERIC International Energy Journal, 11, 35-39.
Delafontaine,M.J., Naveau,H.P. and Nyns E.J. (1979), Fluorimetric monitoring of
methanogenesis in anaerobic digesters, Biotechnology Letters, 1, 71-74.

Table 1 : Production of biogas and volatile acid profile during the development of digesters
at an ambient temperature, 30-35°C

Ambient temperature 30-35°C
Example 1 Example 2 Example 3 Example 4
Activator Ml 0 5 0 7.5 0 10 0 15
Biogas Ml/day 544 1656 600 2400 574 2980 560 4150
Rate of biogas Ml/h 22.6 69 25 100 23.8 124 23 173
Methane % 51 68 51 69 50 68 51 69
Carbon dioxide % 48 31 47 30 47 32 47 30
PH 7.1 6.6 7.1 6.9 7.1 6.6 7.1 6.8
Volatile Acids
Acetate PPM 223 354 363 620 148 347 158 357
Propionate PPM 220 1028 335 971 255 1068 82 825
Butyrate PPM 99 205 145 166 45 240 32 41
Isobutyrate PPM 38 167 ND 283 ND 140 5 219
Valerate PPM 76 970 15 27 10 110 ND 193
Isovalerate PPM 52 140 ND 27 ND ND ND 133
Control digester (1.150 liter) was fed daily with 30 ml of gobar slurry containing 50 % (wet wt/v) gobar.
Experimental digester (1.150 liter) was fed daily with 30 ml of gobar slurry containing 50 % (wet wt/v) gobar and activator.
Data presented is the average of 30 days.
Volatile acids (PPM) of gobar slurry : Acetate, 98; propionate, 304; butyrate, 52; valerate, 20 and isovalerate, 19.
ND: Not detected.

Table 2 : Production of biogas and volatile acid profile during the digestion at low
temperatures.

Ambient Temperature
12-15OC 10-12OC
Period 1-15 days 16-30 days 31-45 days 46-60 days 1-15 days 16-30 days
Activator Ml 0 3 0 3 0 3 0 3 0 3 0 3
Biogas Ml/day 107 535 147 511 170 540 172 528 160 385 150 350
Rate of biogas Ml/h 4.5 22.3 6.1 21.3 7.1 23.3 7.1 22 6.7 16 6.3 14.6
Methane % 50 63 49 65 54 70 55 71 54 70 54 71
Carbon dioxide % 48 36 48 31 45 26 43 26 43 24 40 23
PH 7.0 6.8 7.0 6.7 6.8 6.4 6.7 6.2 6.6 6.2 6.4 6.0
Volatile Acids
Acetate PPM 182 283 120 136 54 830 45 750 82 489 105 560
Propionate PPM 261 1175 90 635 532 998 29 745 62 627 150 780
Butyrate PPM ND 52 18 87 25 51 12 346 18 668 26 816
Isobutyrate PPM ND 18 ND 156 ND ND ND 83 ND ND ND 15
Valerate PPM ND 101 14 165 ND 145 ND 28 ND 99 56 160
Isovalerate PPM ND 58 ND 67 ND ND ND ND ND ND ND 27
Control digester (1.150 liter) was fed daily with 30 ml of gobar slurry containing 50 % (wet wt/v) gobar.
Experimental digester (1.150 liter) was fed daily with 30 ml gobar slurry containing 50 % (wet wt/v) gobar and 3 ml of activator.
Data presented is the average of 15 days.
ND: Not detected.

Table 3 : Production of biogas and volatile acid profile during normalization of digester at
28-32°C.

Normalization of digester
30 days
Control Experimental Gobar slurry
Activator Ml 0 0
Biogas Ml/day 649 690
Methane % 50 70
Carbondioxide % 45 27
PH 6.8 6.0 7.0
Volatile acids
Acetate PPM 1885 1390 98
Propionate PPM 332 1181 304
Butyrate PPM 260 2710 52
Isobutyrate PPM ND 490 ND
Valerate PPM 256 290 20
Isovalerate PPM ND 112 19
ND : Not detected

Claims :
We claim:
1. A process for the production of several folds more biogas with a higher calorific value at
ambient temperatures (25-37°C) as well as at low temperatures (below 15°C) comprises
the following steps of :
a) stabilization of biogas digester by filling a slurry of gobar or of carbonaceous waste to a biogas digester volume and maintaining at ambient temperature ranging from 25°C to 37°C in an air tight condition;
b) development of stabilized biogas digester and production of several folds more biogas at ambient temperature ranging from 25°C to 37°C by feeding a slurry of gobar containing ammonium carbonate, di-potassium hydrogen phosphate and water miscible organic solvents such as methanol;
. c) production of biogas at low temperature, below 15°C, from the developed biogas digester by feeding a slurry of gobar with reduced quantities of ammonium carbonate, di-potassium hydrogen phosphate and methanol; d) normalization of the developed biogas digester at ambient temperature ranging from 28°C to 32°C by feeding a slurry of gobar.
2. A process according to claim 1 wherein said the slurry of gobar is a suspension of wet gobar in water in 1: 1 ratio (wet weight / volume).
3. A process according to claim 1 wherein said the slurry of gobar in step (a) is fed to an air tight biogas digester volume.
4. A process according to claim 1 wherein said the slurry of gobar is reacted as in step (a) for 10 to 30 days to develop anaerobic conditions or for the stabilization of biogas digester.
5. A process according to claim 4 wherein said the stabilization period is 10 days.
6. A process according to claim 1 wherein said temperature in step (a) for stabilization is
25°C to 37°C.
7. A process according to claim 6 wherein said temperature for stabilization is 30°C
to 37°C.
8. A process according to claim 1 wherein said stabilized biogas digester in step (a) is fed one time per day with a slurry of gobar for the development of biogas digester to a hydraulic retention time of 30 days.
9. A process according to claim 1 wherein said biogas digester is fed one time daily as in claim 8 with a slurry of gobar containing varying concentrations of ammonium carbonate, 320 μ mol to 960 μ mol; di-potassium hydrogen phosphate, 15 μ mol to 45 μ mol and methanol, 60 m mol to 180 m mol for the development and production of several folds more biogas.

10.. A process according to claim 9 wherein said biogas digester in step (b) is fed daily with a slurry of gobar containing ammonium carbonate, 640 μ mol; di-potassium hydrogen phosphate, 30 u mol and methanol, 120 m mol at an ambient temperature.
11. A process according to claim 1 wherein said ambient temperature in step ( b) is 25°C to 37°C.
12. A process according to claim 11 wherein said temperature for the-production of several folds, 3 to 7 folds, more biogas from the developed biogas digester is 30°C to 35°C.
13. A process according to claim 12 wherein said a several folds more biogas is rich in methane content, 70 percent, indicates high calorific value.
14. A process according to claim 1.2 wherein said the effluent obtained in step (b) is rich in anaerobic bacteria and methane producing bacteria.
15. A process according to claim 1 wherein said temperature in step. (. c) is 10°C to
16. A process according to claim 15 wherein said biogas production occurs at a temperature
of 12°C to 15°C.
17. A process according to claim 1 wherein said biogas digester in step ( c ) is fed one time per day with a slurry of gobar containing ammonium carbonate, 64 μ, mol to 320 p mol; di-potassium hydrogen phosphate, 3 p mol to 15 p mol and methanol, 12 p mol to 60 p mol for the production of more biogas at low temperature.
18. A process according to clairri 17 wherein said biogas digester is fed one time per day with a slurry of gobar containing ammonium carbonate, 192 p. mol;, di-potassium hydrogen phosphate, 9 p mol and methanol, 36 m mol for the production .of biogas at low temperatures, below 15°C.
19. A process according to claim 18 wherein said produced biogas is rich in methane content, 70 to 71 percent.
20. A process according to claim 18 wherein said the production of biogas is equivalent to the production of biogas at an ambient temperature, 30°C to 35°C, obtained by feeding a same quantity of slurry of gobar only.
A process according to claim 1 wherein said normalization of biogas digester in step ( d) occurs at a temperature at 28°C to 32°C.
22. A process according to claim 1 wherein said a slurry of gobar is fed daily with a stepwise reduction in the concentrations of ammonioum carbonate, 320 μ mol to 0 p mol; di-potassium hydrogen phosphate, 15 p mol to 0 p mol and methanol,60 m mol to 0 m mol for the normalization of biogas digester.

23. A process according to claim 22 wherein said a slurry of gobar is fed one time per day without any supplementation.
24. A process according to claim 1 wherein said a production of biogas by the normalized biogas digester is higher than that of biogas digester without any treatment according to claim 1 as in steps a, b and c.
25. A process according to claim 1 wherein said effluent of normalized biogas digester
contains a rich microflora of nonmethanogenic and methanogenic bacteria.
26. A process according to claim 1 wherein said gobar is a cattle dung or cattle manure and
waste is animal manure or any other carbonaceous waste such as canteen waste,
agriculture waste.
27. A process according to claim 26 wherein said manure or waste is fed to the biogas digester in a form of slurry containing between 8 percent to 10 percent of solids.
28. A process according to claim 1 wherein said waste contains biologically active bacteria include anaerobic microorganisms and methane producing bacteria which convert organic waste to acetate and carbon dioxide and then to methane and carbon .dioxide respectively.
29. A process according to claim 1 wherein said process is semicontinuous
process.
30. A process according to claim 1 wherein said biogas is a gas produced from the group
. consisting mainly of methane, carbon dioxide etc and mixtures thereof.
31. A process according to claim 1 wherein said the production of biogas in step (b) is several folds more than that of other procedures described for production of biogas at an ambient temperatures ranging from 25°C to 37°C.
32. A process according to claim 1 wherein said the production of biogas in step (c) is two folds to five folds more than that of other procedures described for production of biogas at low temperatures ranging from 15°C to 10°C.
33. A process according to claim 1 wherein said the biogas produced is rich in methane content at ambient temperatures ranging from 30°C to 37°C as well as at low temperatures, below 15°C than that of other procedures described for the production of biogas.
Dated this 6th day of Feburary 2003
Signature of the Applicant: (V. S. Rao)
Director
Agharkar Research Institute, Pune

FORM 2
THE PATENTS ACT, 1970
(39 Of 1970)
COMPLETE SPECIFICATION
(See sections 10 )

1. Title of the invention

1. Procedure for the production of several folds more biogas with a higher calorific value at ambient temperatures (25-37°C) as well as at low temperatures (below 15°C).

2. Repeat the columns (a) to (c) if there are more than one applicant

(a) 3. Agharkar Research Institute
(b) 4. G.G. Agarkar Road,
Pune-411 004, Maharashtra, India.

(c)5. Nationality : Indian
3. Insert the name in full. The family or principal name in the beginning if the applicant is a natural person.

4. Insert the complete address including postal index number/ Code and State and /or country

The following specification particularly, describes the nature of the invention and the manner in which it is to be Performed.

5. Insert the nationality

Strike out in case of provisional Specification

GARNTED
29/1/2004

ORIGINAL
162/MUMNP/20003
06/02/03

Procedure for the production of several folds more biogas with a higher calorific value at normal ambient temperatures (25-37°C) as well as at low
temperatures (below 15°C)
This invention relates to an improved process for obtaining several folds more biogas with a high alorific value at low temperatures (10-15°C) as well as at normal ambient temperatures 25-37°C).
n the past a number of attempts have been described for obtaining biogas from cattle dung gobar) at low temperatures. At low temperatures growth of methanogens, methane-producing bacteria, is restricted and methane formation is slowed down. Similarly, activity and growth rate of other bacteria, which produce acetate, CO2 etc also, reduced at low temperature resulting in lecreased production of acetate and CO2. Methanogens are limited in their available substrates acetate and CO2). This narrows range of substrates that can support growth of methanogens. At ow temperatures, methane fermentations may continue slowly and possibly resulting in an nactivation of methane formation and stopped at low temperatures. Therefore in winter, where he temperature of biogas digesters reaches below 15°C, functioning of biogas digesters is everely affected.
Ve have now found that biogas can be produced at low temperatures, 10-15°C, in a good yield several folds more) by a simple procedure using ordinary chemicals as activators along with gobar slurry. If a chemical, which activates growth of methanogens, is supplemented (provided) 0 active methanogens, methane formation gets activated and ultimately a dense culture of nethanogens (a cell-mass) is developed. Similarly ammonium carbonate, ammonia solution, mmonium chloride, diammonium phosphate like ammonium ion producing compounds can be used as a nitrogen source as methanogens utilize free NH4 and it also helps in maintaining pH. We have used ammonium carbonate because it is cheap and very easy to handle. Potassium (K) and PO4 (Phosphate) requirement is satisfied by di-potassium hydrogen phosphate (K2HPO4). Vitamins, trace minerals and other essential components required for the growth of bacteria are vailable from gobar. On this basis, an activator, an aqueous homogeneous mixture, is prepared vith the following composition (per ml of aqueous activator): ammonium carbonate; 64 Μ mol, ii-potassium hydrogen phosphate; 3 μ mol and methanol; 12 m mol.
In object of the present investigation is to produce several folds more biogas by a commercial crocess, which will give good yields of biogas at low temperatures as well as at normal ambient smperatures also. Another object is to produce biogas at low temperature by a semicontineous irocess without the use of highly specialized and expensive equipments and chemicals. A still urther object is to produce biogas with a higher calorific value i.e. biogas containing higher per entage of methane.
an carrying out the process of the present investigation, we have found that the use of essentially
lomogeneous aqueous-methanolic solvents allows a greater degree of intimate contact between
substrates and the microorganisms and thus produces higher yields of biogas. The solvents found.
useful are those miscible with water such as methanol, which promotes growth of some
methanogens. Also found desirable as an excess of ammonium carbonate, which prevents

formation of clumps of methanogens or helps in disaggregation of methanogens resulting in increasing the permeability of the substrates into the cells of methanogens.
The process of the present investigation can be carried out using practically any animal waste, agricultural waste, industrial waste, canteen waste etc in absence of oxygen and in presence of methanogens, however we prefer to use, the cattle dung (gobar) since it is readily available and is also a good source of methanogens. Cattle dung is used as a common substrate to run biogas plants in India. In India, gobar gas plants are popular for generating fuel for domestic purposes. For best results it is necessary to use fifty per cent gobar slurry prepared in water which gives about 9-10 per cent of total solids.
While carrying out the present process, it is desirable to carry out the experiments at the ambient temperature between 25-37°C to stabilize the digester. Best results are obtained at a temperature of 30-35°C. Now the procedure will be more clearly described with reference to Figure of accompanying drawing wherein Figure shows the schematic diagram of a digester for the production of biogas. Referring to Figure, a sturdy container which acts as an anaerobic digester (1), is having an inlet pipe (2) for feeding gobar slurry. Other side of the sturdy container (1) has the outlet pipe (3) with a valve for taking out effluent, which is collected in effluent container (4). There is one more outlet pipe (5) at the top of the digester with a valve for connecting outlet for biogas collected in biogas collector (6). After the stabilization of the 1.150 L glass digester (Fig.l) containing 940 ml of gobar slurry is fed daily with 30 ml of fresh gobar slurry containing varying concentrations of ammonium carbonate (320-960 μ mol), di-potassium hydrogen phosphate (15-45 μ mol) and methanol (60-180 m mol). Best results are obtained when the feeding 30 ml of gobar slurry contains ammonium carbonate; 640 u. mol; di-potassium hydrogen phosphate;30 μ mol and methanol; 120 m mol . The yield of gobar gas is 3-7 fold higher than that of the control digester depending upon concentrations of components of activators. The biogas produced is rich in methane content as compared to that of control. The increase in volatile acids indicates that the activator also activates the growth of nonmethanogenic bacteria. The population of methanogens is also increased indicating an increase in the intensity of factor F420. Factor F420 takes part in methane formation and methane produced is directly proportional to concentration of F420.
After development of biogas digester as above, it is maintained at ambient temperature, 12-15°C and activator with lower concentration is fed daily with 30 ml of gobar slurry containing about 10 per cent total solids. At a concentration of ammonium carbonate; 192 μ mol, di-potassium hydrogen phosphate; 9 μ mol and methanol; 36 m mol in the 30 ml of gobar slurry, the biogas produced is equivalent to the biogas formed by control at an ambient temperature, 30-35°C and it is rich in methane content indicating increase in calorific value of biogas. The effluent obtained will be rich in N:P:K as the added activator consists of ammonium carbonate and di-potassium hydrogen phosphate. The rate of biogas formation is constant. The volatile acids increased indicating the activator also activates the growth of nonmethanogenic bacteria and the increased concentration of volatile acids is not toxic to methanogens. The growth of methanogens as well as concentration of factor F420 is also maintained or increased. This is in sharp contrast to statements in the prior art regarding the biogas production by other processes herein before described and to our experience with these processes.

The following examples illustrate in detail the production of biogas from cattle dung (gobar), at lower temperature (10-15°C) as well as at ambient temperatures (25-37°C), in high yields with higher calorific value by using chemicals to activate the process. The examples are by way of illustration and are not intended to be a limitation of the invention. The present investigation includes stabilization of digester, development of digester, production of biogas at low temperatures and normalization of digester at normal ambient temperature.
Stabilization of a digester : In a 1.150-L glass digester (Fig.l), 940-ml of gobar slurry is kept in an anaerobic condition for 10 days at an ambient temperature (25-37°C). When a sufficient biogas is produced containing 45-50 per cent of methane, then it is confirmed that the digester is stabilized.
Development of a digester : The stabilized digester is fed daily with 30 ml of gobar slurry along with varying concentrations of activator. When a biogas is produced with a constant rate containing 65-69 per cent of methane, then it is assumed that the digester is developed. Microscopic observations of effluent show several folds higher population of methanogens than that of control.
Example 1
Two, 1.150 liter digesters (Fig.l) containing 940 ml of gobar slurry in each are stabilized at 30-35°C, which produced about 500 ml of biogas per day after feeding 30 ml of gobar slurry every day. The biogas contains about 51 per cent methane and 48 per cent CO2. Out of these two digesters one is fed with 30 ml of gobar slurry per day and maintained as a control. Another digester is fed daily with 30 ml of gobar slurry along with activator (5 ml) containing ammonium carbonate; 320 μ mol, di-potassium hydrogen phosphate; 15 μ mol and methanol; 60 m mol. Biogas produced, rate of biogas production, analysis of biogas, pH and composition of volatile acid of effluent slurry are determined. An average data of 30 days is presented in Table 1. A 3-fold more biogas with a high calorific value accounting 68 per cent methane is produced by the activator. supplemented digester as compare to that of control. A dense population of methanogens was developed in the experimental digester. Methanogens in the experimental digester showed bright epifluorescence under ultraviolet light when observed under microscope and cells of clump forming methanogens are disaggregated.
Example 2
An experiment is carried out as in Example 1, and a 30 ml of gobar slurry containing activator (7.5 ml) with concentrations: ammonium carbonate; 480 u. mol, di-potassium hydrogen phosphate;22.5 μ mol and methanol;90 m mol is fed daily to the experimental digester for 30 days. The results (Table 1) indicate that there is a 4 -fold increase in biogas with 69 per cent of methane as compare to that of control. The microscopic observations showed that the population of methanogens was higher than that of control.

Example 3
An experiment is conducted as in Example 1. An activator (10 ml) with the following concentrations : ammonium carbonate; 640 μ mol, di-potassium hydrogen phosphate; 30 μ mol and methanol; 120 m mol in 30 ml of gobar. slurry is fed to the experimental digester. The measurements indicate that there is a 5-fold increase in biogas as compared to that of control. The biogas produced in the experimental digester contains 68 per cent of methane (Table 1). The population of methanogens is more than the control (Table 4) and they showed bright epifluorescence under ultraviolet light when observed under the microscope.
Example 4
An experiment is conducted as above. The gobar slurry, 30 ml, is fed with activator (15 ml) with the following concentrations: ammonium carbonate; 960 u. mol, di-potassium hydrogen phosphate; 45 Μ mol and methanol; 180 m mol. The measurements show that there is about 7-fold increase in biogas with 69 per cent of methane as compared to that of control digester (Table 1). A very dense population of methanogens was developed and showed very bright epifluorescence under ultraviolet light.
Production of biogas at low temperature: The developed digesters, as above are shifted to low temperatures (12-15°C) and the biogas formation is studied.
Example 5
In view to study the biogas formation at low temperature (12-15°C), the digesters in Example 3 are shifted to a cold room, where the temperature is maintained at 12-15°C. For the control digester, 30 ml of gobar slurry is fed daily and for the experimental digester, 30 ml of gobar slurry along with activator (3 ml) having concentrations: ammonium carbonate; 192 u. mol, di-potassium hydrogen phosphate; 9 μ mol and methanol; 36 m mol is fed daily. With this treatment a 5-fold increase in biogas with 63-68 per cent of methane is obtained as compared to that of control (Table 2) and it is almost equivalent to the biogas produced at 30-35 °C by the control digester (Table 1). The experiment is conducted for 60 days. During the period, the rate of biogas formation, methane per centage, yield of biogas is almost constant or increased. There is an increase in volatile acids in the effluent of experimental digester, however the higher concentration of volatile acids is not toxic to methanogens. The overall population of methanogens is slightly decreased (Table 4). The cells of clump-forming methanogens (Methanosarcina) are separated or disaggregated and showed bright epifluorescence under ultraviolet light. Thus, this semicontinuous process illustrates a further advantage of obtaining more biogas at low temperatures (below 15°C).
Example 6
The digesters maintained at 12-15°C in Example 5, are then maintained at 10-12°C in a cold room and biogas formation is studied for 30 days. The experimental digester was fed daily with 30 ml gobar slurry containing 3 ml of activator. In both cases, biogas formation was severely affected. Eventhen the biogas produced in the experimental digester is two folds higher than that

of the control. The methane percentage in the biogas produced by experimental digester is 69-70, whereas in the control it is 54-55 percent (Table 2). At 10-12°C also methanogens show bright epifluorescence. However the activity of methanogens is decreased resulting in decrease in the intensity of F420 (Table 4).
Normalization of digesters :
After the experiments at low temperature, both digesters are shifted to normal ambient temperature (28-32°C), in view to study their functioning at normal ambient temperature. As the bacteria from both digesters are in stress conditions, they took some time for adaptation at normal ambient temperature.
Example 7
After studying the digestion at low temperature, digesters in Example 6 are maintained at ambient temperature 28-32°C to study their functioning at normal ambient temperature. In initial 4-5 days the rate of methane formation is slow. However after that the rate of methane formation increased and both digesters produced methane with a constant rate (Table 3). The experimental digester produced more methane as it contains higher population of methanogens (Table 4). Thus after stress conditions also one can get higher biogas than that of control as the activator helps in producing higher population of methanogens. However, biogas decreases with a slow rate as experimental digester is fed with 30 ml of gobar slurry every day along with decreasing quantities of an activator as expected. And after some days the experimental digester was fed with only 30 ml gobar slurry as a normal feeding.
METHODOLOGY
Stabilization of digester: A digestion of gobar slurry was carried out in 1.150-L fixed dome glass digester (Fig.l) with a working volume of 940 ml. Gobar was diluted 1:1 (wet wt/v) with water and kept in anaerobic condition for 10 days at an ambient temperature (27-32°C). When a sufficient biogas was produced containing 45-50 percent methane then feeding was done at every 24 h for 30 days hydraulic retention time (HRT) using two digesters for the same HRT. Digestion was carried out at normal ambient temperature (25-35°C).
Development of digesters: One of these two stabilized digesters is fed daily with 30 ml of gobar slurry only and maintained as a control. Another digester was fed daily with varying concentrations of activator along with 30 ml of gobar slurry and maintained as an experimental digester. Development of digesters was carried out at normal ambient temperature and at 30 days HRT. When the biogas production of experimental digester reaches several fold higher than that of control and contains 65-69 per cent of methane then it is assumed that the digester is developed.
Biogas production at low temperature: After the development of digesters, digestion was carried out at 12-15°C in an environmental chamber or in a cold room. Feeding of 30 ml of gobar slurry was done every 24 h to the control digester for 60 days. Similarly, experimental digester was fed daily with 30 ml of gobar slurry containing reduced concentrations of activators for 60

days. After studying the biomethanation at 12-15°C, biogas production was also carried out at 10-12°C.
Normalization of digesters: After the digestion at low temperature, digestion was carried out at normal ambient temperature by feeding 30 ml of gobar slurry at every 24 h to the control digester at 30 days HRT and to the experimental digester 30 ml gobar slurry was fed along with decreasing quantities of an activator. Biogas production was compared.
ANALYSIS
Biogas production was monitored daily by displacement of water. Volatile acids, pH of the slurry and methane content in the biogas were measured at weekly intervals. Microbial counts and intensity of factor F420 in the effluent slurry were also monitored at weekly intervals.
Gas analysis: The biogas produced was analyzed for its methane content by using a gas chromatograph (Chemito 3800, Mumbai), equipped with a thermal conductivity detector (TCD) and S.S. column (8' x 1/8") packed with Porapak Q (mesh No. 80/100). Hydrogen (40 ml/min) was used as a carrier gas (Ranade et al 1987).
Volatile acids analysis: Volatile acids were analyzed by using a gas chromatograph (Chemito 8510, Mumbai), equipped with flame ionization detector (FID) and S.S. column (8' x 1/8") packed with 10 per cent FFAP on Chemosorb W (HP) 80/100. Nitrogen (40 ml/min) was used as a carrier gas. The temperature of oven, injector and of detector were set to 150,190 and 200°C respectively (Yeole et al 1989).
Microbial counts: Methanogens and total bacterial counts were taken by microscopic observation under UV-light and with the bright-field microscope respectively using Neubauer chamber. Active methanogens show bright epifluorescence under UV-light. Nonmethanogens were calculated by subtracting counts of methanogens (fluorescent cells) from counts of total bacteria.
Factor F420: Intensity of Factor F42o was measured fluorometrically (Shimadzu Spectrofluorophotometer RF-5301 PC) from alkaline extracts of effluent gobar slurry at Ex-nm 425 and Em-nm 472. To a 9-ml of effluent gobar slurry, 1-ml of 1 N KOH was added and mixed. The extract was centrifuged after 2 h and supernatant was used for fluorometric measurements (Delafontaine et al 1979).
Preparation of an Activator: A weighed quantity (2.5 g) of ammonium carbonate and 250 mg of di-potassium hydrogen phosphate was dissolved in a homogeneous mixture of water and methanol (250:250 ml). This homogeneous mixture is called as an Activator.
References Cited in the file of this patent
Ranade,D.R.,Yeole,T.Y. and Godbole,S.H., (1987),Production of biogas from market waste.
Biomass,13, 147-153.
Yeole,T.Y.,Ranade,D.R. and Gadre,R.V. (1989),Biogas from liquid waste arising in liver and
beef extract production. RERIC International Energy Journal, 11, 35-39.
Delafontaine,M.J., Naveau,H.P. and Nyns E.J. (1979), Fluorimetric monitoring of
methanogenesis in anaerobic digesters, Biotechnology Letters, 1, 71-74.

Table 1 : Production of biogas and volatile acid profile during the development of digesters
at an ambient temperature, 30-35°C

Ambient temperature 30-35°C
Example 1 Example 2 Example 3 Example 4
Activator Ml 0 5 0 7.5 0 10 0 15
Biogas Ml/day 544 1656 600 2400 574 2980 560 4150
Rate of biogas Ml/h 22.6 69 25 100 23.8 124 23 173
Methane % 51 68 51 69 50 68 51 69
Carbon dioxide % 48 31 47 30 47 32 47 30
PH 7.1 6.6 7.1 6.9 7.1 6.6 7.1 6.8
Volatile Acids
Acetate PPM 223 354 363 620 148 347 158 357
Propionate PPM 220 1028 335 971 255 1068 82 825
Butyrate PPM 99 205 145 166 45 240 32 41
Isobutyrate PPM 38 167 ND 283 ND 140 5 219
Valerate PPM 76 970 15 27 10 110 ND 193
Isovalerate PPM 52 140 ND 27 ND ND ND 133
Control digester (1.150 liter) was fed daily with 30 ml of gobar slurry containing 50 % (wet wt/v) gobar.
Experimental digester (1.150 liter) was fed daily with 30 ml of gobar slurry containing 50 % (wet wt/v) gobar and activator.
Data presented is the average of 30 days.
Volatile acids (PPM) of gobar slurry : Acetate, 98; propionate, 304; butyrate, 52; valerate, 20 and isovalerate, 19.
ND: Not detected.

Table 2 : Production of biogas and volatile acid profile during the digestion at low
temperatures.

Ambient Temperature
12-15OC 10-12OC
Period 1-15 days 16-30 days 31-45 days 46-60 days 1-15 days 16-30 days
Activator Ml 0 3 0 3 0 3 0 3 0 3 0 3
Biogas Ml/day 107 535 147 511 170 540 172 528 160 385 150 350
Rate of biogas Ml/h 4.5 22.3 6.1 21.3 7.1 23.3 7.1 22 6.7 16 6.3 14.6
Methane % 50 63 49 65 54 70 55 71 54 70 54 71
Carbon dioxide % 48 36 48 31 45 26 43 26 43 24 40 23
PH 7.0 6.8 7.0 6.7 6.8 6.4 6.7 6.2 6.6 6.2 6.4 6.0
Volatile Acids
Acetate PPM 182 283 120 136 54 830 45 750 82 489 105 560
Propionate PPM 261 1175 90 635 532 998 29 745 62 627 150 780
Butyrate PPM ND 52 18 87 25 51 12 346 18 668 26 816
Isobutyrate PPM ND 18 ND 156 ND ND ND 83 ND ND ND 15
Valerate PPM ND 101 14 165 ND 145 ND 28 ND 99 56 160
Isovalerate PPM ND 58 ND 67 ND ND ND ND ND ND ND 27
Control digester (1.150 liter) was fed daily with 30 ml of gobar slurry containing 50 % (wet wt/v) gobar.
Experimental digester (1.150 liter) was fed daily with 30 ml gobar slurry containing 50 % (wet wt/v) gobar and 3 ml of activator.
Data presented is the average of 15 days.
ND: Not detected.

Table 3 : Production of biogas and volatile acid profile during normalization of digester at
28-32°C.

Normalization of digester
30 days
Control Experimental Gobar slurry
Activator Ml 0 0
Biogas Ml/day 649 690
Methane % 50 70
Carbondioxide % 45 27
PH 6.8 6.0 7.0
Volatile acids
Acetate PPM 1885 1390 98
Propionate PPM 332 1181 304
Butyrate PPM 260 2710 52
Isobutyrate PPM ND 490 ND
Valerate PPM 256 290 20
Isovalerate PPM ND 112 19
ND : Not detected

Claims :
We claim:
1. A process for the production of several folds more biogas with a higher calorific value at
ambient temperatures (25-37°C) as well as at low temperatures (below 15°C) comprises
the following steps of :
a) stabilization of biogas digester by filling a slurry of gobar or of carbonaceous waste to a biogas digester volume and maintaining at ambient temperature ranging from 25°C to 37°C in an air tight condition;
b) development of stabilized biogas digester and production of several folds more biogas at ambient temperature ranging from 25°C to 37°C by feeding a slurry of gobar containing ammonium carbonate, di-potassium hydrogen phosphate and water miscible organic solvents such as methanol;
. c) production of biogas at low temperature, below 15°C, from the developed biogas digester by feeding a slurry of gobar with reduced quantities of ammonium carbonate, di-potassium hydrogen phosphate and methanol; d) normalization of the developed biogas digester at ambient temperature ranging from 28°C to 32°C by feeding a slurry of gobar.
2. A process according to claim 1 wherein said the slurry of gobar is a suspension of wet gobar in water in 1: 1 ratio (wet weight / volume).
3. A process according to claim 1 wherein said the slurry of gobar in step (a) is fed to an air tight biogas digester volume.
4. A process according to claim 1 wherein said the slurry of gobar is reacted as in step (a) for 10 to 30 days to develop anaerobic conditions or for the stabilization of biogas digester.
5. A process according to claim 4 wherein said the stabilization period is 10 days.
6. A process according to claim 1 wherein said temperature in step (a) for stabilization is
25°C to 37°C.
7. A process according to claim 6 wherein said temperature for stabilization is 30°C
to 37°C.
8. A process according to claim 1 wherein said stabilized biogas digester in step (a) is fed one time per day with a slurry of gobar for the development of biogas digester to a hydraulic retention time of 30 days.
9. A process according to claim 1 wherein said biogas digester is fed one time daily as in claim 8 with a slurry of gobar containing varying concentrations of ammonium carbonate, 320 μ mol to 960 μ mol; di-potassium hydrogen phosphate, 15 μ mol to 45 μ mol and methanol, 60 m mol to 180 m mol for the development and production of several folds more biogas.

10.. A process according to claim 9 wherein said biogas digester in step (b) is fed daily with a slurry of gobar containing ammonium carbonate, 640 μ mol; di-potassium hydrogen phosphate, 30 u mol and methanol, 120 m mol at an ambient temperature.
11. A process according to claim 1 wherein said ambient temperature in step ( b) is 25°C to 37°C.
12. A process according to claim 11 wherein said temperature for the-production of several folds, 3 to 7 folds, more biogas from the developed biogas digester is 30°C to 35°C.
13. A process according to claim 12 wherein said a several folds more biogas is rich in methane content, 70 percent, indicates high calorific value.
14. A process according to claim 1.2 wherein said the effluent obtained in step (b) is rich in anaerobic bacteria and methane producing bacteria.
15. A process according to claim 1 wherein said temperature in step. (. c) is 10°C to
16. A process according to claim 15 wherein said biogas production occurs at a temperature
of 12°C to 15°C.
17. A process according to claim 1 wherein said biogas digester in step ( c ) is fed one time per day with a slurry of gobar containing ammonium carbonate, 64 μ, mol to 320 p mol; di-potassium hydrogen phosphate, 3 p mol to 15 p mol and methanol, 12 p mol to 60 p mol for the production of more biogas at low temperature.
18. A process according to clairri 17 wherein said biogas digester is fed one time per day with a slurry of gobar containing ammonium carbonate, 192 p. mol;, di-potassium hydrogen phosphate, 9 p mol and methanol, 36 m mol for the production .of biogas at low temperatures, below 15°C.
19. A process according to claim 18 wherein said produced biogas is rich in methane content, 70 to 71 percent.
20. A process according to claim 18 wherein said the production of biogas is equivalent to the production of biogas at an ambient temperature, 30°C to 35°C, obtained by feeding a same quantity of slurry of gobar only.
A process according to claim 1 wherein said normalization of biogas digester in step ( d) occurs at a temperature at 28°C to 32°C.
22. A process according to claim 1 wherein said a slurry of gobar is fed daily with a stepwise reduction in the concentrations of ammonioum carbonate, 320 μ mol to 0 p mol; di-potassium hydrogen phosphate, 15 p mol to 0 p mol and methanol,60 m mol to 0 m mol for the normalization of biogas digester.

23. A process according to claim 22 wherein said a slurry of gobar is fed one time per day without any supplementation.
24. A process according to claim 1 wherein said a production of biogas by the normalized biogas digester is higher than that of biogas digester without any treatment according to claim 1 as in steps a, b and c.
25. A process according to claim 1 wherein said effluent of normalized biogas digester
contains a rich microflora of nonmethanogenic and methanogenic bacteria.
26. A process according to claim 1 wherein said gobar is a cattle dung or cattle manure and
waste is animal manure or any other carbonaceous waste such as canteen waste,
agriculture waste.
27. A process according to claim 26 wherein said manure or waste is fed to the biogas digester in a form of slurry containing between 8 percent to 10 percent of solids.
28. A process according to claim 1 wherein said waste contains biologically active bacteria include anaerobic microorganisms and methane producing bacteria which convert organic waste to acetate and carbon dioxide and then to methane and carbon .dioxide respectively.
29. A process according to claim 1 wherein said process is semicontinuous
process.
30. A process according to claim 1 wherein said biogas is a gas produced from the group
. consisting mainly of methane, carbon dioxide etc and mixtures thereof.
31. A process according to claim 1 wherein said the production of biogas in step (b) is several folds more than that of other procedures described for production of biogas at an ambient temperatures ranging from 25°C to 37°C.
32. A process according to claim 1 wherein said the production of biogas in step (c) is two folds to five folds more than that of other procedures described for production of biogas at low temperatures ranging from 15°C to 10°C.
33. A process according to claim 1 wherein said the biogas produced is rich in methane content at ambient temperatures ranging from 30°C to 37°C as well as at low temperatures, below 15°C than that of other procedures described for the production of biogas.
Dated this 6th day of Feburary 2003
Signature of the Applicant: (V. S. Rao)
Director
Agharkar Research Institute, Pune

Documents:

162-mum-2003-cancelled pages(29-1-2004).pdf

162-mum-2003-claims(granted)-(29-1-2004).doc

162-mum-2003-claims(granted)-(29-1-2004).pdf

162-mum-2003-correspondence(29-1-2004).pdf

162-mum-2003-correspondence(ipo)-(29-03-2007).pdf

162-mum-2003-drawing(29-1-2004).pdf

162-mum-2003-form 1(29-1-2004).pdf

162-mum-2003-form 1(6-2-2003).pdf

162-mum-2003-form 19(21-7-2003).pdf

162-mum-2003-form 2(granted)-(29-1-2004).doc

162-mum-2003-form 2(granted)-(29-1-2004).pdf

162-mum-2003-form 3(6-2-2003).pdf

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Patent Number

205353

Indian Patent Application Number

162/MUM/2003

PG Journal Number

43/2008

Publication Date

24-Oct-2008

Grant Date

29-Mar-2007

Date of Filing

06-Feb-2003

Name of Patentee

AGHARKAR RESEARCH INSTITUTE

Applicant Address

G.G. AGARKAR ROAD, PUNE - 411 004, MAHARASHTRA, INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	DR. BHOSALE SURESH BHARMAJI	AGHARKAR RESEARCH INSTITUTE, G.G. AGARKAR ROAD, PUNE - 411 004, MAHARASHTRA, INDIA

PCT International Classification Number

C02F 11/04

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA