Title of Invention	"AN IMPROVED PROCESS FOR THE SIMULTANEOUS PRODUCTION OF BIOGAS AND FERTILLIZER BY HIGH RATE BIOMETHANATION OF PALM OIL MILL EFFUENT"
Abstract	The present invention provides anaerobic digestion of palm oil mill effluent POME has been carried through two-step process. The organic material present in the waste matter is ultimately converted in to methane. The whole process is carried out initially under microaerophilic conditions in an acidogenic digester and subsequently under strictly anaerobic conditions at neutral pH in the methanogenic digester. Hydrolysis of complex organic matter present in POME and its further acidogenesis is carried out by a consortia of microbes present in fresh cattle dung.

Title of Invention

"AN IMPROVED PROCESS FOR THE SIMULTANEOUS PRODUCTION OF BIOGAS AND FERTILLIZER BY HIGH RATE BIOMETHANATION OF PALM OIL MILL EFFUENT"

Abstract

The present invention provides anaerobic digestion of palm oil mill effluent POME has been carried through two-step process. The organic material present in the waste matter is ultimately converted in to methane. The whole process is carried out initially under microaerophilic conditions in an acidogenic digester and subsequently under strictly anaerobic conditions at neutral pH in the methanogenic digester. Hydrolysis of complex organic matter present in POME and its further acidogenesis is carried out by a consortia of microbes present in fresh cattle dung.

Full Text	The present invention relates to an improved process for the simultaneous production of biogas mainly containing methane and biofertilizer using high rate biomethanation of palm oil mill effluent. The utility of the present invention is for degradation of an oily industrial effluent (palm oil mill effluent) and energy recovery by high rate biomethanation. The present invention makes use of a simple, cheap and biodegradable source for support material for immobilization of methanogens leading to efficient biomethanation. Anaerobic digestion process has been studied with waste biomasses of different origins (V.C.Kalia and G.Luthra, Bhartiya Vigyan Evam Audhyogic Patrika, 2:38; 1994). The process of anaerobic digestion is a multi step process of degradation of complex organic matter into methane and carbondioxide. A consortium of microbes work in syntrophic association. The process of anaerobic digestion is a multi step process of degradation of complex organic matter. Hydrolysis of complex organic molecules and their further metabolism into volatile fatty acids occurs in acidogenic stage. The intermediates of this process are ultimately converted into methane and carbondioxide during methanogenesis. The process efficiency is dependent upon a host of factors, the prime ones are high loading rate (LR) and low hydraulic retention time (HRT). On loading the reactor with slurry having high Chemical Oxygen Demand (COD), the bacterial metabolism shifts towards generation of high chain fatty acids leading to reactor failure. Feed material has to be invariably diluted. It consequently leads to increased reactor volume. Similarly, HRT determines the reactor volume to be employed for digestion. Because of the slow growing nature of methanogens, the digestion periods i.e., retention of the material in the reactor has to be long. It also consequently leads to use of reactors with larger volumes, which is uneconomical and cumbersome. (POME) typically has an oil and grease content of 4 to 12 g /1. Some work on biomethanation of Palm oil mill effluent (POME) under mesophilic and thermophilic conditions has been reported. (R. Borja and C.J. Banks, Biotech. Letts., 15: 761 ;1993; R. Borja, C.J. Banks and E. Sanchez, J. Biotech., 45: 125;1996).. The major limitations encountered in disposal of different wastes through anaerobic digestion are loading rates and retention times. All efforts are targeted toward increasing efficiency of the process by overcoming these limitations. Liquid wastes with high COD content, if discharged into water bodies, cause water pollution. Hence, it is imperative to dispose of waste and reduce COD levels to within the acceptable limits set by Pollution Control Boards. In this study, the efforts have been concentrated towards developing a bio-process, which can be applied immediately at the industrial / commercial scale. Anaerobic biological systems have been employed for treatment of POME, as they have a low energy demand compared to aerobic treatments (J.O.Edewor, J. Chem. Technol. Biotechnol., 26: 212, 1986; W.J. Ng, K.K. Chin and K.K.Wong, Biol. Wastes, 25: 257. 1987; A.M. Ma and A.S.H. Ong, Biol. Wastes, 23: 85, 1988) The use of conventional anaerobic lagoons (K.S. Hum, N.C. Thann and T.L. Lee, Effluent Water Treatment J., 22, 452, 1981; C.K.John, Water Sci. Technol. 17: 781, 1985) or digesters (C.C. Ho and Y.K.Tan, J. Chem. technol. Biotechnol, 25: 155, 1985) to treat POME is characterized by long residence times of the slurry in the reactor, for generally more than 20 days, which requires large areas of land or large digesters. The application of modern anaerobic digesters such as up-flow or down- flow filters; fluidized beds, up-flow anaerobic sludge blankets (UASB) systems or up-flow floe digesters, for the disposal of POME is rare. (R. Borja, C.J. Banks and E. Sanchez, J. Biotech., 45: 125;1996). Hitherto some of the conventional process parameters employed for anaerobic digestion of different wastes of plant origin have been characterised. (V.C. Kalia and A.P. Joshi, Bioresource Technology, 53 : 165, 1995; V.C. Kalia, D.C. Pant and A.P. Joshi, Proc. R'95 Congress : Recovery, Recycling, Reintegration, Geneva, Vol. IV: 227, 1995; V.C. Kalia, V. Anand, A. Kumar and A.P. Joshi, Proc. R'97 Congress : Recovery, Recycling, Reintegration, Geneva, Vol. I: 200, 1997). For improving the efficiency of biomethanation process, maximum loading rates at shortest retention periods are desired. The digesters for treating POME have employed biomass from anerobic reactor processing wine distillery waste water (R. Borja and C.J. Banks, Biotech. Letts., 15: 761;1993) and brewery waste water as inoculum for treating soft drink waste water (R. Borja and C.J. Banks, Biotech. Letts., 15: 767;1993), however use of cattle dung as inoculum for POME treatment has not been reported. Although, cattle dung as inoculum has been reported for other wastes. ((V.C. Kalia and A.P. Joshi, Bioresource Technology, 53 : 165, 1995; V.C. Kalia, D.C. Pant and A.P. Joshi, Proc. R'95 Congress : Recovery, Recycling, Reintegration, Geneva, Vol. IV: 227, 1995; V.C. Kalia, V. Anand, A. Kumar and A.P. Joshi, Proc. R'97 Congress : Recovery, Recycling, Reintegration, Geneve Vol. I: 200, 1997). In all the methods so far used for treatment of POME, the major limitations are related to hydraulic retention time (HRT), which has been observed to be 6 to 30 days (T.O.Peyton, I.W. Cooper and S.K. Quah, Proc. 34th Indust. Waste Conf., Purdue Univ., Lafayette. 1979; K.K.Chin, Water Res. 15: 199, 1981, R.G. Cail and J.P. Barford, Biomass, Z: 287,1985). Another limiting factor for increasing the efficiency have been the various loading rates and influent COD concentration employed for the biodegradation of POME i.e. 6.2 to 18 g/l/day COD and influent COD concentration of 16 g/l. (R.G. Call and J.P. Barford, Biomass, Z: 287, 1985, R. Borja and C.J. Banks, Biomass Bioenergy, 6: 381, 1994, R. Borja, C.J. Banks and E. Sanchez, J. Biotech., 45: 125;1996). Attempts to run the digester at high influent concentration (42.5 g/l COD) have resulted in reactor instability. (R. Borja, C.J. Banks and E. Sanchez, J. Biotech., 45: 125;1996). Although 80% COD was removed in another process, but the loading rates were still very low, i.e., upto 10.6 g/l/day COD (R. Borja and C.J. Banks, Biomass Bioenergy, 5: 381, 1994). Another limitation is instability of digester at high loading rates, that is the gas production declines within few days. (R. Borja, C.J. Banks and E. Sanchez, J. Biotech., 45: 125;1996). In the present invention we have over come the major limitations involved in the biomethanation of POME, which obviates the limitations listed above. The novelty of the present invention is in establishing the parameters for high rate biomethanation of palm oil mill effluent, to operate at high influent loading in to the digester at very low hydraulic retention time. In the present invention, bioenergy has been generated from oily industrial effluent of oil mill of Karnataka wherein palm oil have been processed using fruits of palm trees grown in Karnataka. The present invention also uses a simple and cheap source of biodegradable support material for immobilization of enriched methanogens collected from Delhi for effective biomethanation. In the present invention, cattle dung has been used as inoculum source for treating POME. The main object of present invention is to provide an improved process for the simultaneous production of biogas mainly containing methane and biofertilizer using high rate biomethanation of palm oil mill effluent, obviates the drawbacks as detailed above. Another object of present invention is to complete the degradation process with a very low hydraulic retention time (HRT), Another object of present invention is to generate energy rich clean fuel from renewable resource i.e. waste biomass, in a short period. Yet another object of present invention is to retain bacterial population for longer time in the bioreactor, for effective biomethanation. This leads to digestion of larger quantites of the feed material. Accordingly the present invention provides an improved process for the simultaneous production of biogas and biofertilizer by high rate biomethanation of palm oil mill effluent, characterized in that the palm oil is treated with acidogenic bacteria and subsequently by methanogenic bacteria in a specific ratio to get high rate biomethanation , which comprising the steps of: i) sieving floating oily and fibrous matter from fresh feed material, Palm Oil Mill Effluent (POME), by conventional manner, ii) mixing sieved palm oil mill effluent (POME) with water and adding fresh cattle dung in the form of slurry {3 to 5% Total solids, TS} in the said specific ratio of 9:0.5 to 9:1 (v/v), wherein said slurry contain acidogenic bacteria mainly Bacillus cereus. Bacillus knelfelkampi, Bacillus megaterium, Bacteroides succinogenes, Clostridium carnofoetidum, Clostridium flavifacients. iii) incubating the mixture obtained as above at a temperature in the range of 35 to 42°C for a period of 3-5 days to obtain acidified slurry, in a conventional manner, iv) subjecting the acidified slurry obtained above in step (iii) to methanogenesis under strict anaerobic conditions in digester by adding 5 to 10% (v/v) of digested cattle dung containing methanogens namely Methane-bacterium suboxydans, methanobacterium formicum, methane-bacterium mobilis. Methane-bacterium propionicum, methane-coccus mazei, Methanosarcina barkerii. methanosarcina methanica in the from of slurry ( 3 to 5% Total solids) for a period of 6 h, and incubating the slurry for methanogenesis for a period of 5-25 days , v) collecting the biogas produced in gas holders by water displacement and biofertilizer from the bottom of the digester. in a conventional manner In an embodiment of present invention, the digestion may be done in batch culture and continuous culture. In another embodiment of present invention, the cattle dung slurry used in step (ii) may contain acidogenic bacteria mainly : Bacillus cereus, Bacillus knelfelkampi, Bacillus meaaterium, bacteroides succinoaenes. Clostridium carnofoetidum. Clostridium flavifacients. In still another embodiment of present invention, the incubation is effected for a period which may range from 2 to 3 days, In another embodiment of present invention, the micro-organisms of digested cattle dung in step (iv) may be free floating or immobilized. In yet another embodiment of present invention, the digested cattle dung may contain methanogens such as: Methanobactenum suboxydans. Methanobacterium formicum. Methanobacterium mobilis. Methanobacterium propionicum. Methanococcus maze/. Methanosarcina barkerii. Methanosarcina methanica. ' In still another embodiment of present invention, the methanogenesis may be effected for 5 to 25 days, In yet another embodiment of present invention, the feed COD load may be in the range from 17.5 to 88 g COD/I feed. Details of the invention: In the present invention anaerobic digestion of POME has been • / carried through two-step process. The organic material present in the waste t matter is ultimately converted in to methane! and carbon dioxide. The whole process can be carried out initially under microaerophilic conditions in an acidogenic digester and subsequently under strictly anaerobic conditions at neutral pH in the methanogenic digester. Hyrolysis of complex organic matter present in POME and its futher t'ddogenesis is carried out by a consortia of microbes present in fresh cattle dung.'.The fermentation products of partial digestion of waste material i.e., acidogenesis, determines the efficiency of methanogenesis process. In this work the POME slurries were inoculated with fresh cattle dung slurry. Under fermentative conditions, these fermentative bacterial populations produced volatile fatty acids, hydrogen, carbon dioxide, alcohols, etc. These intermediates are then passed on to next digester having methanogens enriched in different manner. Since methanogens are slow growing bacteria, they get drained out at short retention periods. In order to retain bacterial population in the digester, for effective metabolism of volatile fatty acids and other intermediates of methane metabolism, biodegradable support material for example banana leaves were used. The period of optimum biogas evolution helps to determine the period of methanogenesis. A combination of these periods and feed at different concentrations allowed us to establish parameters for effective biodegradation of POME. The major by products of this process, methane and CO2 were recovered and analysed by gas chromatography. The digested slurry is rich in nutrients, particularly nitrogen, potassium and phosphorous, and can be used as soil addendum for improving the quality of soil. The invention has been described herein below with examples which are illustrative only and should not be construed to limit the scope of the present invention. EXAMPLE 1: For batch culture digestions, 50 ml of Palm Oil Mill Effluent (POME) was sieved to remove floating oily and fibrous matter. 20 ml sieved POME undiluted or diluted 2 to 5 times with water, (COD : 17500 to 88,000 mg/l) was inoculated with 2.5 ml cattle dung slurry (3% Total solids) and incubated at 35°C for 2 days. 2.5 ml of enriched free floating methanogen culture (5% v/v) was added to the acidified slurry and incubated at 37°C for 25 days. pH of material was adjusted to 7.0, in the beginning of methanogenesis, with 1N NaOH. The treated material was tested for its total solids, organic solids. Biogas was collected by water displacement. Methane (CH4) was analysed by gas chromatography and volumes were estimated and recorded regularly. The treated effluent was collected in a plastic container and allowed to settle. The supernatent was separated by decentation. The sludge, biofertilizer was collected and sun dried. The detailed results are as given below in the Table. Comparitive biogas and methane yields from POME under different Batch culture conditions (Table Removed) N: Normal feed. N/2: Feed diluted 2 times. N/5 : Feed diluted 5 times. eCDS: Enriched cattle dung slurry. EXAMPLE 2: In batch culture, 50ml of Palm Oil Mill Effluent (POME) was sieved to remove floating oily and fibrous matter. 20 ml sieved POME undiluted or dilued 2 times with water, (COD : 44000 to 88000 mg/l) was inoculated with 2.5 ml cattle dung slurry (5% Total solids) and incubated at 37°C for 2 days. 2.5 ml of enriched and immobilized methanogen culture (5% v/v), was added to the acidified slurry and incubated at 40°C for 25 days. pH of material was adjusted to 7.0, in the beginning of methanogenesis, with 1N NaOH. The treated material was tested for its total solids, organic solids. Biogas was collected by water displacement. Methane (CH4) was analysed by gas chromatography and volumes were estimated and recorded regularly. The treated effluent was collected in a plastic container and allowed to settle. The supernatent was separated by decentation. The sludge, biofertilizer was collected and sun dried. The detailed results are as given below in the Table. Comparitive biogas and methane yields from POME under different Batch culture conditions (Table Removed) N: Normal feed. N/2: Feed diluted 2 times. eCDS(BL): Enriched cattle dung slurry immobilized on banana leaves. EXAMPLE 3 In continuous culture, 200 ml of Palm Oil Mill Effluent (POME) was sieved to remove floating oily and fibrous matter. 100 ml sieved POME (COD: 88,000 mg/l) was inoculated with 10 ml cattle dung slurry (3% Total solids) and incubated at 42°C for 2-3 days. 100 ml of the acidified slurry was transferred to the methanogenic digester. Here, the slurry was incubated at 42°C for 5 days and methanogens were immobilized on biodegradable support material, which occupied 10% v/v of the reactor volume. After 5 days, the process of draining out 100 ml of treated material from methanogenic stage and subsequently transferring 100 ml of acidified slurry from acidogenic stage was followed every day. 100 ml of sieved POME : CDS 9 :1 (v/v i.e. 10% CDS) was replenished to acidogenic stage. pH of material from acidogenic stage to methanogenic stage was adjusted to 7.0 through out the incubation period with 1N NaOH, only if the pH of the slurry fell below 6.5. The process was monitored for 40 days. The effluent was tested for its following components total solids, organic solids, volatile fatty acids and Chemical Oxygen Demand. Biogas was collected by water displacement. Methane (CH4) was analysed by gas chromatography and volumes were estimated and recorded regularly. The treated effluent was collected in a plastic container and allowed to settle. The supernatent was separated by decentation. The sludge, biofertilizer was collected and sun dried. The detailed results are as given below in the Table. Continuous culture biomethanation of POME (Table Removed) EXAMPLE 4. In continuous culture, 100 ml Palm Oil Mill Effluent (POME) was sieved to remove floating oily and fibrous matter. 50 ml sieved POME (COD : 88,000 mg/l) was inoculated with 5 ml cattle dung slurry (10% Total Solids) and incubated at 40°C for 2 days, 50 ml slurry was transferred to methanogenic digester. Here the slurry was kept for 10 days and methanogens were immobilized on biodegradable support material, which occupied 10% v/v of the reactor volume. After 10 days, the process of draining out 50 ml of treated material from methanogenic stage and subsequently transferring 50ml of acidified slurry from acidogenic stage was followed every day. 50 ml of sieved POME : CDS 9 :1 (v/v i.e 10% CDS) was replenished to acidogenic stage. pH of material from acidogenic stage to methanogenic stage was adjusted to 7.0 for the 1st few days. There after there was autoregulation of pH due to biological activity. No alkali or acid additions were done at any stage. The process was monitored for 40 days. The effluent was tested for its following components total solids, organic solids, volatile fatty acids and Chemical Oxygen Demand. Biogas and methane (CH4) volumes were recorded regularly. Biogas was collected by water displacement. Methane (CH4) was analysed by gas chromatography and volumes were estimated and recorded regularly. In the digested effluent sludge settles at the bottom and occupies a volume of 22 to 26%. The treated effluent was collected in a plastic container and allowed to settle. The supernatent was separated by decentation. The sludge, biofertilizer was collected and sun dried. Biofertilizer had a composition of 0.726% nitrogen, 1.770% phosphorous and 0.57% potassium (w/w). Biofertilizer was optionally dried. The detailed results are as given below in the Table. Continuous culture biomethanation of POME (Table Removed) EXAMPLE 5 In continuous culture, 100 ml Palm Oil Mill Effluent was sieved to remove floating oily and fibrous matter. 60 ml sieved POME (COD: 59,500 mg/l) was inoculated with 5 ml cattle dung slurry (3% Total Solids) and incubated at 40°C for 2 days, 60 ml slurry was transferred to methanogenic digester. Here the slurry was kept for 5 days and methanogens were immobilized on biodegradable support material which occupied 20 % v/v of the reactor volume. After 5 days, the process of draining out 60 ml of treated material from methanogenic stage and subsequently transferring 60 ml of acidified slurry from acidogenic stage was followed every day. 60 ml of sieved POME: CDS 9 :1 (v/v i.e 10% CDS) was replenished to acidogenic stage. pH of material from acidogenic stage to methanogenic stage was adjusted to 7.0 during the first few days of incubation period with 1N NaOH. There after there was autoregulation of pH due to biological activity. No alkali or acid additions were done at any stage. The process was monitored for 32 days. This experiment, with 20% v/v immobilizing support material (biodegradable), could sustain the bioactivity for long. The effluent was tested for its following components total solids, organic solids, volatile fatty acids and Chemical Oxygen Demand. Biogas and methane (CH4) volumes were recorded regularly. Biogas was collected by water displacement. Methane (CH4) was analysed by gas chromatography and volumes were estimated and recorded regularly. In the digested effluent sludge settles at the bottom and occupies a volume of 20 to 25%. The sludge, Biofertilizer had a composition of 0.752% nitrogen, 2.030% phosphorous and 0.709% potassium (w/w). Biofertilizer was optionally dried. The detailed results are as given below in the Table. Continuous culture biomethanation of POME (Table Removed) The main advantages of the present invention are : 1. In this process 60 to 80% reduction in COD is achieved. 2. Biogas with 66% methane content, is generated, which is a high value product and can be used as a source of clean fuel-bioenergy. 3. It provides an efficient process for disposal of industrial waste i.e., POME, which has high COD content of 80000 to 90000 mg/l. 4. It also provides a high rate biomethanation process, which lead to the generation of methane at high efficiency of 330 L CH4 / kg COD reduced. 5. The nutrient rich fertilizer can be used as soil addendum. We claim: 1. An improved process for the simultaneous production of biogas and biofertilizer by high rate biomethanation of palm oil mill effluent, characterized in that the palm oil is treated with acidogenic bacteria and subsequently by methanogenic bacteria in a specific ratio to get high rate biomethanation , which comprising the steps of: i) sieving floating oily and fibrous matter from fresh feed material, Palm Oil Mill Effluent (POME), by conventional manner, ii) mixing sieved palm oil mill effluent (POME) with water and adding fresh cattle dung in the form of slurry {3 to 5% Total solids, TS} in the said specific ratio of 9:0.5 to 9:1 (v/v), wherein said slurry contain acidogenic bacteria mainly Bacillus cereus, Bacillus knelfelkampi. Bacillus megaterium, Bacteroides succinogenes. Clostridium carnofoetidum, Clostridium flavifacients, iii) incubating the mixture obtained as above at a temperature in the range of 35 to 42°C for a period of 3-5 days to obtain acidified slurry, in a conventional manner, iv) subjecting the acidified slurry obtained above in step (iii) to methanogenesis under strict anaerobic conditions in digester by adding 5 to 10% (v/v) of digested cattle dung containing methanogens namely Methanobacterium suboxydans, methane-bacterium formicum, methane-bacterium mobilis, Methanobacterium propionicum, methanococcus maze/. Methanosarcina barkerii, methanosarcina methanica in the from of slurry ( 3 to 5% Total solids) for a period of 6 h, and incubating the slurry for methanogenesis for a period of 5-25 days , v) collecting the biogas produced in gas holders by water displacement and biofertilizer from the bottom of the digester. in a conventional manner 2. An improved process as claimed in claim 1, wherein the digested cattle dung in step (iv) contains micro-organisms either free floating or immobilized. 3. An improved process for the simultaneous production of biogas and fertilizer by high rate biomethanation of palm oil mill effluent, substantially herein described with reference to examples 1 to 5.

Full Text

The present invention relates to an improved process for the simultaneous production of biogas mainly containing methane and biofertilizer using high rate biomethanation of palm oil mill effluent.
The utility of the present invention is for degradation of an oily industrial effluent (palm oil mill effluent) and energy recovery by high rate biomethanation. The present invention makes use of a simple, cheap and biodegradable source for support material for immobilization of methanogens leading to efficient biomethanation.
Anaerobic digestion process has been studied with waste biomasses of different origins (V.C.Kalia and G.Luthra, Bhartiya Vigyan Evam Audhyogic Patrika, 2:38; 1994). The process of anaerobic digestion is a multi step process of degradation of complex organic matter into methane and carbondioxide. A consortium of microbes work in syntrophic association. The process of anaerobic digestion is a multi step process of degradation of complex organic matter. Hydrolysis of complex organic molecules and their further metabolism into volatile fatty acids occurs in acidogenic stage. The intermediates of this process are ultimately converted into methane and carbondioxide during methanogenesis. The process efficiency is dependent upon a host of factors, the prime ones are high loading rate (LR) and low hydraulic retention time (HRT). On loading the reactor with slurry having high Chemical Oxygen Demand (COD), the bacterial metabolism shifts towards generation of high chain fatty acids leading to reactor failure. Feed material has to be invariably diluted. It consequently leads to increased reactor volume. Similarly, HRT determines the reactor volume to be

employed for digestion. Because of the slow growing nature of methanogens, the digestion periods i.e., retention of the material in the reactor has to be long. It also consequently leads to use of reactors with larger volumes, which
is uneconomical and cumbersome. (POME) typically has an oil and grease

content of 4 to 12 g /1. Some work on biomethanation of Palm oil mill effluent (POME) under mesophilic and thermophilic conditions has been reported. (R. Borja and C.J. Banks, Biotech. Letts., 15: 761 ;1993; R. Borja, C.J. Banks and E. Sanchez, J. Biotech., 45: 125;1996)..
The major limitations encountered in disposal of different wastes through anaerobic digestion are loading rates and retention times. All efforts are targeted toward increasing efficiency of the process by overcoming these limitations. Liquid wastes with high COD content, if discharged into water bodies, cause water pollution. Hence, it is imperative to dispose of waste and reduce COD levels to within the acceptable limits set by Pollution Control Boards. In this study, the efforts have been concentrated towards developing a bio-process, which can be applied immediately at the industrial / commercial scale.
Anaerobic biological systems have been employed for treatment of POME, as they have a low energy demand compared to aerobic treatments (J.O.Edewor, J. Chem. Technol. Biotechnol., 26: 212, 1986; W.J. Ng, K.K. Chin and K.K.Wong, Biol. Wastes, 25: 257. 1987; A.M. Ma and A.S.H. Ong, Biol. Wastes, 23: 85, 1988) The use of conventional anaerobic lagoons (K.S. Hum, N.C. Thann and T.L. Lee, Effluent Water Treatment J., 22, 452, 1981; C.K.John, Water Sci. Technol. 17: 781, 1985) or digesters (C.C. Ho and

Y.K.Tan, J. Chem. technol. Biotechnol, 25: 155, 1985) to treat POME is characterized by long residence times of the slurry in the reactor, for generally more than 20 days, which requires large areas of land or large digesters. The application of modern anaerobic digesters such as up-flow or down- flow filters; fluidized beds, up-flow anaerobic sludge blankets (UASB) systems or up-flow floe digesters, for the disposal of POME is rare. (R. Borja, C.J. Banks and E. Sanchez, J. Biotech., 45: 125;1996).
Hitherto some of the conventional process parameters employed for anaerobic digestion of different wastes of plant origin have been characterised. (V.C. Kalia and A.P. Joshi, Bioresource Technology, 53 : 165, 1995; V.C. Kalia, D.C. Pant and A.P. Joshi, Proc. R'95 Congress : Recovery, Recycling, Reintegration, Geneva, Vol. IV: 227, 1995; V.C. Kalia, V. Anand, A. Kumar and A.P. Joshi, Proc. R'97 Congress : Recovery, Recycling, Reintegration, Geneva, Vol. I: 200, 1997). For improving the efficiency of biomethanation process, maximum loading rates at shortest retention periods are desired. The digesters for treating POME have employed biomass from anerobic reactor processing wine distillery waste water (R. Borja and C.J. Banks, Biotech. Letts., 15: 761;1993) and brewery waste water as inoculum for treating soft drink waste water (R. Borja and C.J. Banks, Biotech. Letts., 15: 767;1993), however use of cattle dung as inoculum for POME treatment has not been reported. Although, cattle dung as inoculum has been reported for other wastes. ((V.C. Kalia and A.P. Joshi, Bioresource Technology, 53 : 165, 1995; V.C. Kalia, D.C. Pant and A.P. Joshi, Proc. R'95 Congress : Recovery, Recycling, Reintegration, Geneva, Vol. IV: 227, 1995; V.C. Kalia,

V. Anand, A. Kumar and A.P. Joshi, Proc. R'97 Congress : Recovery, Recycling, Reintegration, Geneve Vol. I: 200, 1997).
In all the methods so far used for treatment of POME, the major limitations are related to hydraulic retention time (HRT), which has been observed to be 6 to 30 days (T.O.Peyton, I.W. Cooper and S.K. Quah, Proc. 34th Indust. Waste Conf., Purdue Univ., Lafayette. 1979; K.K.Chin, Water Res. 15: 199, 1981, R.G. Cail and J.P. Barford, Biomass, Z: 287,1985).
Another limiting factor for increasing the efficiency have been the various loading rates and influent COD concentration employed for the biodegradation of POME i.e. 6.2 to 18 g/l/day COD and influent COD concentration of 16 g/l. (R.G. Call and J.P. Barford, Biomass, Z: 287, 1985, R. Borja and C.J. Banks, Biomass Bioenergy, 6: 381, 1994, R. Borja, C.J. Banks and E. Sanchez, J. Biotech., 45: 125;1996). Attempts to run the digester at high influent concentration (42.5 g/l COD) have resulted in reactor instability. (R. Borja, C.J. Banks and E. Sanchez, J. Biotech., 45: 125;1996). Although 80% COD was removed in another process, but the loading rates were still very low, i.e., upto 10.6 g/l/day COD (R. Borja and C.J. Banks, Biomass Bioenergy, 5: 381, 1994).
Another limitation is instability of digester at high loading rates, that is the gas production declines within few days. (R. Borja, C.J. Banks and E. Sanchez, J. Biotech., 45: 125;1996).
In the present invention we have over come the major limitations involved in the biomethanation of POME, which obviates the limitations listed above. The novelty of the present invention is in establishing the parameters

for high rate biomethanation of palm oil mill effluent, to operate at high influent loading in to the digester at very low hydraulic retention time. In the present invention, bioenergy has been generated from oily industrial effluent of oil mill of Karnataka wherein palm oil have been processed using fruits of palm trees grown in Karnataka. The present invention also uses a simple and cheap source of biodegradable support material for immobilization of enriched methanogens collected from Delhi for effective biomethanation. In the present invention, cattle dung has been used as inoculum source for treating POME.
The main object of present invention is to provide an improved process for the simultaneous production of biogas mainly containing methane and biofertilizer using high rate biomethanation of palm oil mill effluent, obviates the drawbacks as detailed above.
Another object of present invention is to complete the degradation process with a very low hydraulic retention time (HRT),
Another object of present invention is to generate energy rich clean fuel from renewable resource i.e. waste biomass, in a short period.
Yet another object of present invention is to retain bacterial population for longer time in the bioreactor, for effective biomethanation. This leads to digestion of larger quantites of the feed material.
Accordingly the present invention provides an improved process for the simultaneous production of biogas and biofertilizer by high rate biomethanation of palm oil mill effluent, characterized in that the palm oil is treated with acidogenic bacteria and subsequently by methanogenic bacteria in a specific ratio to get high rate biomethanation , which comprising the steps of: i) sieving floating oily and fibrous matter from fresh feed material, Palm Oil Mill Effluent
(POME), by conventional manner,
ii) mixing sieved palm oil mill effluent (POME) with water and adding fresh cattle dung in the form of slurry {3 to 5% Total solids, TS} in the said specific ratio of 9:0.5 to 9:1

(v/v), wherein said slurry contain acidogenic bacteria mainly Bacillus cereus. Bacillus knelfelkampi, Bacillus megaterium, Bacteroides succinogenes, Clostridium carnofoetidum, Clostridium flavifacients.
iii) incubating the mixture obtained as above at a temperature in the range of 35 to 42°C for a period of 3-5 days to obtain acidified slurry, in a conventional manner, iv) subjecting the acidified slurry obtained above in step (iii) to methanogenesis under strict anaerobic conditions in digester by adding 5 to 10% (v/v) of digested cattle dung containing methanogens namely Methane-bacterium suboxydans, methanobacterium formicum, methane-bacterium mobilis. Methane-bacterium propionicum, methane-coccus mazei, Methanosarcina barkerii. methanosarcina methanica in the from of slurry ( 3 to 5% Total solids) for a period of 6 h, and incubating the slurry for methanogenesis for a period of 5-25 days , v) collecting the biogas produced in gas holders by water displacement and biofertilizer from the bottom of the digester. in a conventional manner
In an embodiment of present invention, the digestion may be done in batch culture and continuous culture.
In another embodiment of present invention, the cattle dung slurry used in step (ii) may contain acidogenic bacteria mainly : Bacillus cereus, Bacillus knelfelkampi, Bacillus meaaterium, bacteroides succinoaenes. Clostridium carnofoetidum. Clostridium flavifacients.
In still another embodiment of present invention, the incubation is effected for a period which may range from 2 to 3 days,
In another embodiment of present invention, the micro-organisms of digested cattle dung in step (iv) may be free floating or immobilized.

In yet another embodiment of present invention, the digested cattle
dung may contain methanogens such as: Methanobactenum suboxydans.
Methanobacterium formicum. Methanobacterium mobilis. Methanobacterium
propionicum. Methanococcus maze/. Methanosarcina barkerii.
Methanosarcina methanica. '
In still another embodiment of present invention, the methanogenesis may be effected for 5 to 25 days,
In yet another embodiment of present invention, the feed COD load may be in the range from 17.5 to 88 g COD/I feed.
Details of the invention:
In the present invention anaerobic digestion of POME has been
*• /*
carried through two-step process. The organic material present in the waste
t
matter is ultimately converted in to methane! and carbon dioxide. The whole process can be carried out initially under microaerophilic conditions in an acidogenic digester and subsequently under strictly anaerobic conditions at neutral pH in the methanogenic digester. Hyrolysis of complex organic matter present in POME and its futher t'ddogenesis is carried out by a consortia of microbes present in fresh cattle dung.'.The fermentation products of partial digestion of waste material i.e., acidogenesis, determines the efficiency of methanogenesis process. In this work the POME slurries were inoculated with fresh cattle dung slurry. Under fermentative conditions, these fermentative bacterial populations produced volatile fatty acids, hydrogen, carbon dioxide, alcohols, etc. These intermediates are then passed on to next digester having methanogens enriched in different manner. Since

methanogens are slow growing bacteria, they get drained out at short retention periods. In order to retain bacterial population in the digester, for effective metabolism of volatile fatty acids and other intermediates of methane metabolism, biodegradable support material for example banana leaves were used. The period of optimum biogas evolution helps to determine the period of methanogenesis. A combination of these periods and feed at different concentrations allowed us to establish parameters for effective biodegradation of POME. The major by products of this process, methane and CO2 were recovered and analysed by gas chromatography. The digested slurry is rich in nutrients, particularly nitrogen, potassium and phosphorous, and can be used as soil addendum for improving the quality of soil.
The invention has been described herein below with examples which are illustrative only and should not be construed to limit the scope of the present invention.
EXAMPLE 1:
For batch culture digestions, 50 ml of Palm Oil Mill Effluent (POME) was sieved to remove floating oily and fibrous matter. 20 ml sieved POME undiluted or diluted 2 to 5 times with water, (COD : 17500 to 88,000 mg/l) was inoculated with 2.5 ml cattle dung slurry (3% Total solids) and incubated at 35°C for 2 days. 2.5 ml of enriched free floating methanogen culture (5% v/v) was added to the acidified slurry and incubated at 37°C for 25 days. pH of material was adjusted to 7.0, in the beginning of methanogenesis, with 1N

NaOH. The treated material was tested for its total solids, organic solids. Biogas was collected by water displacement. Methane (CH4) was analysed by gas chromatography and volumes were estimated and recorded regularly. The treated effluent was collected in a plastic container and allowed to settle. The supernatent was separated by decentation. The sludge, biofertilizer was collected and sun dried. The detailed results are as given below in the Table.
Comparitive biogas and methane yields from POME under different Batch culture conditions

(Table Removed)
N: Normal feed. N/2: Feed diluted 2 times. N/5 : Feed diluted 5 times. eCDS: Enriched cattle dung slurry.
EXAMPLE 2:
In batch culture, 50ml of Palm Oil Mill Effluent (POME) was sieved to remove floating oily and fibrous matter. 20 ml sieved POME undiluted or dilued 2 times with water, (COD : 44000 to 88000 mg/l) was inoculated with 2.5 ml cattle dung slurry (5% Total solids) and incubated at 37°C for 2 days. 2.5 ml of enriched and immobilized methanogen culture (5% v/v), was added to the acidified slurry and incubated at 40°C for 25 days. pH of material was

adjusted to 7.0, in the beginning of methanogenesis, with 1N NaOH. The treated material was tested for its total solids, organic solids. Biogas was collected by water displacement. Methane (CH4) was analysed by gas chromatography and volumes were estimated and recorded regularly. The treated effluent was collected in a plastic container and allowed to settle. The supernatent was separated by decentation. The sludge, biofertilizer was collected and sun dried. The detailed results are as given below in the Table.
Comparitive biogas and methane yields from POME under different Batch culture conditions

(Table Removed)
N: Normal feed. N/2: Feed diluted 2 times.
eCDS(BL): Enriched cattle dung slurry immobilized on banana leaves.
EXAMPLE 3
In continuous culture, 200 ml of Palm Oil Mill Effluent (POME) was sieved to remove floating oily and fibrous matter. 100 ml sieved POME (COD: 88,000 mg/l) was inoculated with 10 ml cattle dung slurry (3% Total solids) and incubated at 42°C for 2-3 days. 100 ml of the acidified slurry was transferred to the methanogenic digester. Here, the slurry was incubated at 42°C for 5 days and methanogens were immobilized on biodegradable

support material, which occupied 10% v/v of the reactor volume. After 5 days, the process of draining out 100 ml of treated material from methanogenic stage and subsequently transferring 100 ml of acidified slurry from acidogenic stage was followed every day. 100 ml of sieved POME : CDS 9 :1 (v/v i.e. 10% CDS) was replenished to acidogenic stage. pH of material from acidogenic stage to methanogenic stage was adjusted to 7.0 through out the incubation period with 1N NaOH, only if the pH of the slurry fell below 6.5. The process was monitored for 40 days. The effluent was tested for its following components total solids, organic solids, volatile fatty acids and Chemical Oxygen Demand. Biogas was collected by water displacement. Methane (CH4) was analysed by gas chromatography and volumes were estimated and recorded regularly. The treated effluent was collected in a plastic container and allowed to settle. The supernatent was separated by decentation. The sludge, biofertilizer was collected and sun dried. The detailed results are as given below in the Table. Continuous culture biomethanation of POME
(Table Removed)

EXAMPLE 4.
In continuous culture, 100 ml Palm Oil Mill Effluent (POME) was sieved to remove floating oily and fibrous matter. 50 ml sieved POME (COD : 88,000 mg/l) was inoculated with 5 ml cattle dung slurry (10% Total Solids) and incubated at 40°C for 2 days, 50 ml slurry was transferred to methanogenic digester. Here the slurry was kept for 10 days and methanogens were immobilized on biodegradable support material, which occupied 10% v/v of the reactor volume. After 10 days, the process of draining out 50 ml of treated material from methanogenic stage and subsequently transferring 50ml of acidified slurry from acidogenic stage was followed every day. 50 ml of sieved POME : CDS 9 :1 (v/v i.e 10% CDS) was replenished to acidogenic stage. pH of material from acidogenic stage to methanogenic stage was adjusted to 7.0 for the 1st few days. There after there was autoregulation of pH due to biological activity. No alkali or acid additions were done at any stage. The process was monitored for 40 days. The effluent was tested for its following components total solids, organic solids, volatile fatty acids and Chemical Oxygen Demand. Biogas and methane (CH4) volumes were recorded regularly. Biogas was collected by water displacement. Methane (CH4) was analysed by gas chromatography and volumes were estimated and recorded regularly. In the digested effluent sludge settles at the bottom and occupies a volume of 22 to 26%. The treated effluent was collected in a plastic container and allowed to settle. The supernatent was separated by decentation. The sludge, biofertilizer was collected and sun dried. Biofertilizer had a composition of 0.726% nitrogen, 1.770% phosphorous and 0.57%

potassium (w/w). Biofertilizer was optionally dried. The detailed results are as given below in the Table.
Continuous culture biomethanation of POME
(Table Removed)
EXAMPLE 5
In continuous culture, 100 ml Palm Oil Mill Effluent was sieved to remove floating oily and fibrous matter. 60 ml sieved POME (COD: 59,500 mg/l) was inoculated with 5 ml cattle dung slurry (3% Total Solids) and incubated at 40°C for 2 days, 60 ml slurry was transferred to methanogenic digester. Here the slurry was kept for 5 days and methanogens were immobilized on biodegradable support material which occupied 20 % v/v of the reactor volume. After 5 days, the process of draining out 60 ml of treated material from methanogenic stage and subsequently transferring 60 ml of acidified slurry from acidogenic stage was followed every day. 60 ml of sieved POME: CDS 9 :1 (v/v i.e 10% CDS) was replenished to acidogenic stage. pH of material from acidogenic stage to methanogenic stage was adjusted to 7.0

during the first few days of incubation period with 1N NaOH. There after there was autoregulation of pH due to biological activity. No alkali or acid additions were done at any stage. The process was monitored for 32 days. This experiment, with 20% v/v immobilizing support material (biodegradable), could sustain the bioactivity for long. The effluent was tested for its following components total solids, organic solids, volatile fatty acids and Chemical Oxygen Demand. Biogas and methane (CH4) volumes were recorded regularly. Biogas was collected by water displacement. Methane (CH4) was analysed by gas chromatography and volumes were estimated and recorded regularly. In the digested effluent sludge settles at the bottom and occupies a volume of 20 to 25%. The sludge, Biofertilizer had a composition of 0.752% nitrogen, 2.030% phosphorous and 0.709% potassium (w/w). Biofertilizer was optionally dried. The detailed results are as given below in the Table.
Continuous culture biomethanation of POME
(Table Removed)

The main advantages of the present invention are :
1. In this process 60 to 80% reduction in COD is achieved.
2. Biogas with 66% methane content, is generated, which is a high value
product and can be used as a source of clean fuel-bioenergy.
3. It provides an efficient process for disposal of industrial waste i.e.,
POME, which has high COD content of 80000 to 90000 mg/l.
4. It also provides a high rate biomethanation process, which lead to the
generation of methane at high efficiency of 330 L CH4 / kg COD
reduced.
5. The nutrient rich fertilizer can be used as soil addendum.

We claim:
1. An improved process for the simultaneous production of biogas and biofertilizer by high rate biomethanation of palm oil mill effluent, characterized in that the palm oil is treated with acidogenic bacteria and subsequently by methanogenic bacteria in a specific ratio to get high rate biomethanation , which comprising the steps of:
i) sieving floating oily and fibrous matter from fresh feed material, Palm Oil Mill Effluent (POME), by conventional manner,
ii) mixing sieved palm oil mill effluent (POME) with water and adding fresh cattle dung in the form of slurry {3 to 5% Total solids, TS} in the said specific ratio of 9:0.5 to 9:1 (v/v), wherein said slurry contain acidogenic bacteria mainly Bacillus cereus, Bacillus knelfelkampi. Bacillus megaterium, Bacteroides succinogenes. Clostridium carnofoetidum, Clostridium flavifacients,
iii) incubating the mixture obtained as above at a temperature in the range of 35 to 42°C for a period of 3-5 days to obtain acidified slurry, in a conventional manner,
iv) subjecting the acidified slurry obtained above in step (iii) to methanogenesis under strict anaerobic conditions in digester by adding 5 to 10% (v/v) of digested cattle dung containing methanogens namely Methanobacterium suboxydans, methane-bacterium formicum, methane-bacterium mobilis, Methanobacterium propionicum, methanococcus maze/. Methanosarcina barkerii, methanosarcina methanica in the from of slurry ( 3 to 5% Total solids) for a period of 6 h, and incubating the slurry for methanogenesis for a period of 5-25 days ,

v) collecting the biogas produced in gas holders by water displacement and biofertilizer from the bottom of the digester. in a conventional manner
2. An improved process as claimed in claim 1, wherein the digested cattle dung
in step (iv) contains micro-organisms either free floating or immobilized.
3. An improved process for the simultaneous production of biogas and fertilizer
by high rate biomethanation of palm oil mill effluent, substantially herein
described with reference to examples 1 to 5.

Documents:

32-del-2000-abstract.pdf

32-del-2000-claims.pdf

32-del-2000-correspondence-others.pdf

32-del-2000-correspondence-po.pdf

32-del-2000-description (complete).pdf

32-del-2000-form-1.pdf

32-del-2000-form-19.pdf

32-del-2000-form-2.pdf

32-del-2000-form-3.pdf

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Patent Number

216808

Indian Patent Application Number

32/DEL/2000

PG Journal Number

13/2008

Publication Date

31-Mar-2008

Grant Date

19-Mar-2008

Date of Filing

18-Jan-2000

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	VIPIN CHANDRA KALIA	CENTRE FOR BIOCHEMICAL TECHNOLOGY, MALL ROAD, UNIVERSITY CAMPUS, DELHI-110007, INDIA.
2	TANUJA ROHATGI	CENTRE FOR BIOCHEMICAL TECHNOLOGY, MALL ROAD, UNIVERSITY CAMPUS, DELHI-110007, INDIA.
3	VIKAS SONAKYA	CENTRE FOR BIOCHEMICAL TECHNOLOGY, MALL ROAD, UNIVERSITY CAMPUS, DELHI-110007, INDIA.
4	NEENA RAIZADA	CENTRE FOR BIOCHEMICAL TECHNOLOGY, MALL ROAD, UNIVERSITY CAMPUS, DELHI-110007, INDIA.
5	ARVIND PURSHOTTAM JOSHI	NATIONAL CHEMICAL LABORATORY, PASHAN ROAD, PUNE -411 008, INDIA.

PCT International Classification Number

C02F 1/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA