JJT ENHANCEMENT OF BIOGAS PRODUCTION USING AGRICULTURAL AND AQUATIC WASTES IN SMALL SCALE REACTOR

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1 JJT ENHANCEMENT OF BIOGAS PRODUCTION USING AGRICULTURAL AND AQUATIC WASTES IN SMALL SCALE REACTOR Chitra Devi.T 1, Prasanth.K 2, Sathya Prabha.P 3 and R. Ravikumar 4 1,2,3,4 Department of Biotechnology, Bannari Amman Institute of Technology, Sathyamangalam, Erode District , TamilNadu, India E mail: chitrapkrs@gmail.com ABSTRACT The present research work was focused to investigate a novel method for increasing the biogas production in an anaerobic lab scale reactor using agricultural and aquatic wastes. Batch experiment was conducted for the co-digestion of buffalo dung with water hyacinth (Eichhornia crassipes), Parthenium (Parthenium hysterophorus) and Bermuda grass (Cynodon dactylon) for a period of 20 days with the total solid concentration of 8% in the fermentation slurry. Results revealed that the rate of biogas production was enhanced by adding rumen fluid to the mixture. The average volume of biogas produced was 85 ml/kg substrate/day. The maximum of mg/l Volatile Fatty Acid was produced with the reduction in ph from 7.1 to 5.8 after 7 days. It was also observed that the decrease in total Solid % from 8% to 5.9% leads to the gradual increase in biogas production. This technology will help the society to manage Energy scarcity with Environmental protection by remediating the pollution caused by water hyacinth and Parthenium. Key words: anaerobic reactor, biogas, buffalo dung and rumen fluid. INTRODUCTION Energy is one of the most important factors to be considered for the global prosperity. The dependence on fossil fuels as primary energy source has lead to global climate change, environmental degradation, and human health problems. In the year 2040, the world predicted will have 9 10 billion people and must be provided with energy and materials (Okkerse and Bekkum, 1999). Due to scarcity of petroleum and coal, the demand of fuel throughout the world has increased to a large extent. So there is an urgent need for the research community to focus on new sources of energy, like renewable energy resources. Solar energy, wind energy, different thermal and hydro sources of energy, biogas are all renewable energy resources. Moreover, the recent rise in oil and natural gas prices has driven the current economy towards alternative energy sources such as biogas. Biogas does not have any geofigureical limitations nor does it require advanced technology for producing energy, also it is very simple to use and apply. The biogas is generally used for the production of electricity. BIOGAS is produced by bacteria through the bio-degradation of organic material under anaerobic conditions. It usually contains 50% and above methane and other gases in relatively low proportions namely, CO 2, H 2, N 2 and O 2 (Kalia et al., 2000). Organic substances exist in wide variety from living beings to dead organisms. Organic matters are composed of Carbon (C), combined with elements such as Hydrogen (H), Oxygen (O), Nitrogen (N), and Sulphur (S) to form variety of organic compounds such as carbohydrates, proteins & lipids. In nature MOs (microorganisms), through digestion process breaks the complex carbon into smaller substances (Gunnarsson and Petersen, 2007). Biogas, a clean and renewable form of energy could very well substitute (especially in the rural sector) for conventional sources of energy (fossil fuels, oil, etc.) which are causing ecological environmental problems and at the same time depleting at a faster rate. Despite its numerous advantages, the potential of biogas technology could not be fully harnessed or tapped as certain constraints are also associated with it. Most common among these are: the large hydraulic retention time of days, low gas production in 21

2 winter, etc. Therefore, efforts are needed to remove its various limitations so as to popularize this technology in the rural areas. Researchers have tried different techniques to enhance gas production (Yadvika, 2004). The present work is focused on the co-digestion of buffalo dung with agricultural and aquatic weeds like Water hyacinth (Eichhornia crassipes), Parthenium weed (Parthenium hysterophorus) and Green Grass-Bermuda (Cynodon dactylon) for biogas production and the enhancement in the rate of biogas production with the help of Rumen fluid and other additives. OBJECTIVES To enhance the biogas production from agricultural and aquatic weeds like Water hyacinth, Parthenium weed and Green Grass with inoculum as buffalo dung To study the rate of biogas production with and without additives MATERIALS AND METHODS Sample collection and preparation Water hyacinth used in this research was collected from local pond in Somanur, Coimbatore, TamilNadu. Parthenium and Green grass were collected from local agricultural land in Avinashi, Tiruppur, TamilNadu. Buffalo dung was collected from local farm house in Avinashi. Rumen fluid was collected from slaughter house in Sathyamangalam. The substrates were dried at room temperature for 3 days and made into one mm size powder form. The inoculum was mixed completely with the substrate then made up to final volume with distilled water. The fermentation slurry was subjected to analyze its Total solid % (TS) and Volatile Solid % (VS) Fig.1: Schematic diagram of experimental set up. A - Lab scale anaerobic reactor; B Biogas phial; C Liquid reservoir; D Biogas storage unit; 1 - biogas production in reactor; 2 - transfer of brine solution from the phial to the reservoir to measure the biogas volume produced daily; 3 - displacement of brine solution from the reservoir to the phial; 4 - resulting transfer of biogas accumulated daily in the phial to biogas storage unit. Batch study for Biogas production without Rumen fluid Batch experiment was conducted in 5 L anaerobic lab scale reactor by mixing 250 g of each substrate with 250 g of fresh buffalo dung. The final volume of 4 L was made with distilled water. Initial ph and TS % was noted. Two days once the parameters like ph, TS % and VFA content were determined. The volume of Biogas produced was found out by liquid displacement method using 90% NaCl solution (brine) (Yetilmezsoy and Sakar, 2008). The ph was found out with the help of ph meter (Make: Sartorius & Model: PB-11). Batch study with Rumen fluid Similar Batch experiment was conducted in 5 L anaerobic lab scale reactor by mixing 250 g of each substrate with 250 g of fresh buffalo dung and to that 500ml Rumen fluid was added. The final volume of 4 L was made with distilled water. All parameters analyzed above the experiment were again found out for this study. Analytical Methods and calculations (APHA, 1998): Total Solids (TS %): The sample, approximately 10 gm is taken and poured in foil plate and dried to a constant weight at about 105 C in hot air oven (Make: Heraeus 7000 series & Model: UT12). TS % = (Final weight/initial weight) 100 Volatile Solids (VS %) Dried residue from Total Solid analysis weighed and heated in crucible for 2hrs at 500 C in furnace. After cooling crucible residue weighed. VS % = [100-(V3-V1/V2-V1)]

3 V1= Weight of crucible. V2= Weight of dry residue & crucible. V3= Weight of ash & crucible (after cooling) Volatile Fatty Acid (VFA) The sample collected was filtered and ph was noted. 20 ml of filtrate was taken and 0.1M HCl was added until ph reaches 4. Then the liquid was heated in the hot plate for 3 mins. The sample was titrated with 0.01M NaOH to reach 7. The amount of HCl & NaOH was recorded. Total VFA content in mg/l acetic acid = (Volume of NaOH titrated) 87.5 RESULTS AND DISCUSSION Substrates collection and drying The substrates used in the study (fig. 2A, 2B & 2C) were collected, dried at room temperature and made into powder form. Biogas production in batch study The volume of biogas and the parameters like ph, TS % and VFA were found out from both experiments like with and without rumen fluid. The average volume of biogas produced by co digestion of buffalo dung with these substrates was 60.5 ml/kg substrate/day. Similarly the average volume of biogas produced by co digestion of buffalo dung with these substrates and with rumen fluid was 85 ml/kg substrate/day. This was represented in fig. 3. The rate of biogas production was higher in slurry having rumen fluid than slurry without rumen fluid. This was due to presence of microbial load in rumen fluid. The increase in the microbial load in fermentation slurry resulted in enhanced biogas production. Initially biogas production was started from buffalo dung biomass and then the microbes present in the dung and rumen fluid started digesting the substrates by converting it into smaller metabolic compounds. Finally it was resulted in continuous production of biogas. Fig. 2: A) Water hyacinth B) Parthenium & C) Green 23

4 Fig. 3 : Volume of biogas produced by the substrates on daily basis Similarly study revealed that the biogas production from water hyacinth (Eichhornia crassipes) grown under the different nitrogen concentrations was studied and reported that The highest gas production rate was observed in the digester amounting to 193 ml/l/day on the 5th day and produced continuously (Jayaweera et al., 2007). The parameters of biomethanation optimized at 4-L level digester showed that 25 days retention time, 7.5 ph and C ambient temperature were optimum for admixture of Ipomoea biomass and distillery waste as substrate for biomethanation. The large volume of biogas could be produced (161 L/kg/day) with high percent methane content from admixture of Ipomoea biomass and distillery waste, which can generate a revenue (Deshmukh and Bartakke, 2012). decomposes by the actions of microorganisms under anaerobic conditions to produce biogas. The total solids (TS) concentration of the waste influences the ph, temperature and effectiveness of the microorganisms in the decomposition process. It was reported that the percentage total solids (PTS) of municipal solid waste in an anaerobic continuous digestion process increases, there is a corresponding geometric increase for biogas produced and simultaneous decrease in total solid % during the course of production process (Igoni et al., 2008). Initially in both the cases the ph was kept as 7.0 and the ph of the fermentation slurry was reduced first and increased slowly. This indicated the production of Volatile Fatty Acids (VFA) like acetate, propionate and butyrate that favours the methane production. It was represented in fig. 5. In the presence of rumen fluid, the ph of the slurry was decreased upto 5.1 on 12 th day and slowly increased. But in the absence of the rumen fluid, the ph was reduced to 5.6 during 8 th day itself. The ph reduction was higher in case of the slurry having rumen fluid than other. It was proved that the methane production was strongly dependent on the ph of the slurry or the substrate. Fig. 4 : Effect of Total Solid % on biogas production The amount of Total Solids% was reduced from 8% to 5.9% in case of slurry with rumen fluid where as TS% from 7.7% to 6.2% in case of slurry without rumen fluid. It revealed that the reduction in total solids% leads to increase in biogas production. Highest reduction in total solids % was observed in the slurry with rumen fluid that directly related to biogas production. This was shown in fig 4. Municipal Solid Waste (MSW) contains a relatively large amount of organic matter, which Fig. 5 : ph variations during biogas production For increased gas yield, a ph between 7.0 and 7.2 is optimum, though the gas production was satisfactory between ph 6.6 and 7.6 as well. The ph of the digester is a function of the concentration of volatile fatty acids produced, bicarbonate alkalinity of the system, and the amount of carbon dioxide produced (Chawla, 1986). Similarly the 24

5 production of biogas from cow dung, pig and chicken manures and from water hyacinth-cow dung mixture was studied and the ph varies from 6.7 to 8.0 in water hyacinth-cow dung mixture (Ntengwe et al., 2010). CONCLUSION From the study it was revealed that water hyacinth, Parthenium weed and green grass could be used as best substrate for biogas production. Rumen fluid was best additive to increase the rate of biogas production. The substrates used above are also causing pollution to the environment. So this technology can reduce this problem as well as to produce biogas. The digested substrate is used as manure for agricultural purpose. FUTURE ENHANCEMENTS The biogas production from the same substrates will be studied in continuous mode with daily loading and it will be optimized. The efficiency of the produced biogas will be increased to get high calorific biofuel. The sludge obtained form this technology can be tested for nutrient content for the use of Biofertilizers Igoni, A.H., Abowei, M.F.N., Ayotamuno, M.J. and Eze, C.L. (2008), Effect of Total Solids Concentration of Municipal Solid Waste on the Biogas produced in an Anaerobic Continuous Digester, Journal of Food, Agriculture & Environment, Vol.5, pp Jayaweera, M.W., Dilhani, J.A.T., Kularatne, R.K.A. and Wijeyekoon, S.L.J. (2007), Biogas production from water hyacinth (Eichhornia crassipes (Mart.) Solms) grown under different nitrogen concentrations, Journal of Environmental Science and Health Part A: Toxic/Hazardous Substances and Environmental Engineering, Vol.42, No.7, pp Kalia, V.C., Sonakya, V. and Raizada, N, (2000), Anaerobic digestion of banana stems waste, Bioresource Technology, Vol.73, pp Ntengwe, F.W., Njovu, L., Kasali, G. and Witika, L.K. (2010), Biogas production in cone-closed floating dome Batch digester under tropical Conditions, International Journal of Chemical Technology Research, Vol.2, No.1, pp ACKNOWLEDGEMENT 8. Okkerse, C. and Bekkum, H.V. (1999), The authors acknowledge the farmers in Avinashi, Tiruppur who provided the substrates and cattle dung for this work. We wish to express our heartfelt thanks to the management of Bannari Amman Institute of Technology, Sathyamangalam, India for helping us to carry out this research in the Chemical Engineering Laboratory. From fossil to green, Green Chemistry, Vol.1, pp REFERENCES 1. APHA, (1998), Standard Methods for the Examination of Water and Wastewater, 20 th American Public Health Association, American Water Works Association and Water Environment Federation 2. Chawla, O. P., (1986), Advances in Biogas Technology, Indian Council of Agricultural Research, New Delhi, pp Deshmukh, H.V. and Bartakke, G.R. (2012), Co-utilization of common weed Ipomoea carnea along with distillery waste for biogas production, International Journal on Current Sciences, Vol.13, pp Gunnarsson, C.C. and Petersen, C.M. (2007), Water hyacinths as a resource in agriculture and energy production: a literature review, Waste Management, Vol.27, pp Yadvika, S., Sreekrishnan, T.R., Kohli, S. and Rana, V. (2004), Enhancement of biogas production from solid substrates using different techniques-a review, Bioresource Technology, Vol.95, pp Yadvika, S., Sreekrishnan, T.R., Kohli, S. and Rana, V. (2004), Enhancement of biogas production from solid substrates using different techniques-a review, Bioresource Technology, Vol.95, pp.1-10 Idea Leads to Solutions