Pak. J. Biotechnol. Vol. 14 (3) 437-442 (2017) ISSN Print: 1812-1837 www.pjbt.org ISSN Online: 2312-7791 PRODUCTION OF BIOGAS FROM VARIOUS BIOMASS WASTE A.Vijin Prabhu 1 *, S. Antony Raja 1, C. Lindon Robert Lee 1, P. Jeba 2 1 Department of Mechanical Engineering, Karunya University, Coimbatore, 641114, Tamil Nadu, India. 2 Renewable Energy Technology, Karunya University, Coimbatore, 641114, Tamil Nadu, India. Email: *vijinprabhua@gmail.com Article received 3.8.2017, Revised 29.8.2017, Accepted 7.9.2017 ABSTRACT: The anaerobic digestion(ad) of different biomass wastes [Prosopis juliflora (PJ) pods, PJ leaves, grass clippings (GC), dry leaves (DL), parthenium (P), water hyacinth (WH), and cow manure (CM)] were investigated. Two stage of experiments were carried out, to find the daily biogas yield, biogas composition, and the cumulative biogas production. In the first stage of experimentation, anaerobic digestion of seven materials was carried out in the different reactor to find out the biogas yield. The best three materials in terms of biogas production were selected for the second stage of experimentation. In the second stage of experimentation co-digestion of three combinations (PJ pods + DL, PJ pods + WH, and PJ pods + DL + WH) were analyzed. In the first experiment, PJ pods showed the maximum biogas production (45.69 l/kg) and WH showed the highest biogas composition (CH 4:79.89% and CO 2:19.87%). However, parthenium performed worst in the biogas production (20.12 l/kg) and biogas composition (CH 4:13.45% and CO 2:66.57%). CM has quicker production of biogas (maximum from 12 15 days) than other materials. The second experiment PJ pods + DL + WH combination showed the maximum biogas production (65.41 l/kg) and the biogas composition (CH 4:75.89% and CO 2:23.81%). Key words: biomass; anaerobic digestion; co-digestion; biogas; biogas composition; methane. INTRODUCTION To satisfy the future energy needs the alternative ways to be found to limit the fossil fuel resources and optimize the utilization of the existing resources. The potential solution for future energy requirements will be the renewable energy technologies. This will reduce the effect of the greenhouse gases (GHG) and also it will provide energy. Biomass, the photovoltaic cell, hydro, biofuel, wind, etc., are the various renewable energy sources.it will play an important role in sustainable energy development (Khaparde et al., 2007). Manure in livestock residues, sugar cane bagasse in agriculture and pulp and paper residues in forestry are the most successful forms of biomass. It is argued that fossil fuels can be directly substituted by biomass. It was more effective in decreasing atmospheric CO 2 than carbon sequestration in trees. There are many ways to produce energy from the biomass may gasification, anaerobic digestion, combustion, and fermentation are the most common methods (Patel and Barot 2014). In liquid manure systems, the decomposition of organic matter by bacteria or AD naturally occurs in the absence of oxygen. The proper conditions for anaerobic bacteria to survive will be the abundance of organic matter and the lack of oxygen in liquid manure (Leggett et al.,). AD of residues, wastes, and energy crops are increasing interest to facilitate a sustainable development of energy supply and to reduce the greenhouse gas emissions. Biogas Production provides a versatile carrier of renewable energy. The methane can be used for replacement of fossil fuels in both heat and power generation and as a vehicle fuel (Weiland et al., 2010). To obtain maximal biogas yield in anaerobic digestion with the optimal range of ph was 6.5 7.5. The range was relatively more in the plant scale. The optimal value of ph varies with digestion 5 technique and substrate. All microbial mediated substrate conversion processes were subject to inhibition by extremes of ph (Liu et al., 2008). Rene et.al., had examined the performance of anaerobic digestion by the effects of daily temperature variations. The large cyclic variations in the methane content and the rate of gas production are the causes of variations of temperature (Alvarez and Liden 2008). The increase of hydraulic retention time (HRT) will increase as the cellulose reduction of feed stocks. Longer the feed resided in the digester, the more cellulose was degraded and utilized by the microbes (Luste and Luostarinen, 2010). Co-digestion is usually too dilute inhibitors/toxic compounds and balance nutrients (C/N ratio and macro and micronutrients), thus improving CH 4 production. To improve an efficiency of the AD process, it requires careful selection of combining two or more feed stocks (Zhu et al., 2014). However, to enhance biogas productivity co-digesting three agricultural residues, i.e., oat straw, wheat straw and corn stalks with swine manure was investigated by Xiao et.al.,. Corn stalks and oat straw has a higher biogas productivity than wheat
438 Prabhu, A.J. et al. Pak. J. Biotechnol. straw even it had higher carbon content (46%) than the latter two residues (39%) (Wu et al., 2010). Co-digestion of dog food with corn stover reduced the volatile fatty acid (VFA) accumulation and startup time but decreased the xylan degradation of corn stover and cellulose (Xu and Li 2012). The objective of this study was to evaluate the methane composition and biogas yield. Biogas yield was measured in terms of cumulative biogas yield and daily biogas yield. In the first stage of the experimental test was carried out in anaerobic digestion of seven different biomass waste materials. Co-digestion of PJ pods, DL, and WH at three different combinations (PJ pods + DL, PJ pods + WH, and PJ pods + DL + WH) was carried out in the second experimental test. The biogas yield value was presented in l/kg and the biogas composition was presented in % by volume. MATERIALS AND METHODS Materials: Prosopis juliflora (PJ) pods, PJ leaves, grass clippings (GC), dry leaves (DL), parthenium (P), water hyacinth (WH), and cow manure (CM) were the various feed materials for this research. Prosopis juliflora is a small tree or shrub in the Fabaceae family, a kind of mesquite. It is native to the Caribbean, South America and Mexico. It has become established as an unfriendly weed in Australia, Asia, Africa and other places. Parthenium is fast growing which come up in abundance in gomal (range) lands, road sides, fallow lands. PJ pods, PJ leaves, parthenium and cow manure were collected from nearby village, WH from a lake, DL and grass clippings were collected from our University campus in Karunya University, Coimbatore, Tamil Nadu, India. All the feed materials were crushed in a commercial blender and reduced the particle size to 3-5 mm diameter. Before crushing the DL, is soaked in water for stress-free crushing process. The crushed feed materials were mixed with water to from feed slurry and fed to the digester for anaerobic digestion. Experimental Setup: The experimental setup consist of anaerobic digester with water bath for biogas production and water displacement setup to measure biogas production. For batch testing a 1 liter bottle of the digester were used. To extract the biogas, the bottle is sealed and connected with a pipe. A gas collection system consisting of a serum bottles, in which the water is displaced according to the gas collection. The digester was connected to the gas collection system. The reactors were ensured for anaerobic conditions for prior to operation. Thereafter, the digester was placed in a water bath and that will maintain the temperature of 37 ± 2 o C. The measurement of amount of gas collected has to be made regularly. If there is no significant gas production the experiments were terminated. The experimental setup is shown in fig.1. The photographic view of experimental setup shown in fig.2. Analytical methods: According to the standard methods, The TS and VS of the test samples were measured (APHA et al., 1998). According to the method, the VFA content in the sample is determined as described in (Buchauer et al., 1998). Carbon, hydrogen and nitrogen was analyzed by and the ph was measured by ph meter (Eliot LI 120). Water displacement method is used to measure the daily biogas production. Gas chromategraphy is used to monitor the biogas composition (CH 4 and CO 2) (GC 2014, Shimadzu in Japan) with nitrogen as gas carrier, equipped with a Shin Carbon ST column (packed with carbon molecular sieve, 2 m 1.0 mm) and a thermal conductivity detector (TCD). The temperatures of column, TCD and injector port were 260, 110, and 250 o C, respectively. Experimental methods: The crushed feed materials were mixed with the same amount of CM. This CM helps to provide the microorganism for anaerobic digestion. Then add the tap water to form Fig. 1. Experimental setup Fig. 2. The photographic view of experimental setup
Vol. 14 (3) 2017 Production of biogas.. 439 Table I: Characteristics of feed materials Properties PJ pods PJ Leaves GC P DL WH CM Moisture content/% 67.23 63.08 26.38 61.08 8.61 85.64 78.86 Total solid(ts)/% 32.77±0.41 36.92±0.39 73.62±0.68 38.92±0.56 91.39±1.22 14.36±0.36 21.14±0.62 Volatile solid(vs)/% 29.23±0.29 32.58±0.28 66.12±0.41 33.13±0.32 89.70±1.06 11.19±0.24 16.15±0.41 VS/TS/% 89.19 88.24 89.81 85.12 98.15 77.96 76.4 C/% 42.06 - - 38.32 39.57 33.57 30.99 H/% 6.73 - - - 5.91 5.82 - N/% 2.35 - - 1.60 1.49 1.55 1.93 C/N 17.89 - - 23.95 26.55 21.65 16.05 Table II: Characteristics of the influents and effluents of the digester Sl.No Feed influent ph TS % VS % VFA g/kg Initial Final Initial Final Initial Final Initial Final First Experiment 1 PJ pods 6.9-7 7.4-7.5 12.6±0.8 8.1 ±0.2 86.7±0.6 77.1±0.7 5.8±0.62 5.1±0.62 2 PJ leaves 6.4-6.5 7.8-7.9 10.0±0.2 6.3±0.2 82.4±0.3 74.8±0.4 2.1±0.73 1.9±0.77 3 GC 6.5-6.7 7.4-7.5 8.9±0.2 4.7±0.3 84.1±0.2 75.7±0.6 1.7±0.50 1.5±0.31 4 DL 6.8-6.9 7.8-7.9 15.1±0.1 13.2±0.2 89.3±0.9 81.7±0.8 4.2±0.32 3.4±0.47 5 Parthenium 5-5.1 4.6-4.7 8.7±0.5 6.6±0.8 79.1±0.2 71.4±0.3 3.6±0.41 3.8±0.50 6 WH 7.2-7.4 7.8-7.9 5.6±0.05 4.5±0.2 78.5±0.1 69.3±0.2 5.4±0.23 3.5±0.46 7 Cow Manure 7-7.1 6.7-6.9 6.7±0.2 4.7±0.3 77.2±0.2 65.3±0.4 3.7±0.18 4.7±0.25 Second Experiment 8 PJ pods+dl 6.7-6.8 7.3-7.4 10.3±0.4 5.9±0.4 83.7±0.8 75.6±0.3 7.2±0.21 6.4±0.52 9 PJ pods+wh 7.1-7.2 7.4-7.6 7.5±0.3 5.4±0.6 81.2±0.4 70.8±0.3 8.2±0.31 6.8±0.45 10 PJ pods+ DL+WH 6.6-6.9 7.5-7.6 8.7±0.4 5.5±0.3 84.2±0.3 71.3±0.4 7.7±0.48 5.8±0.57 a feed slurry. The slurry was gently mixed manually for feeding. In the first stage of experiment the feed materials loaded in the separate batch reactor for experimentation. Out of the seven materials three best materials in terms of biogas production (PJ pods, DL, WH) is selected for co-digestion. In the second stage of experimentation the co-digestion experiments performed under three combinations (PJ pods + DL, PJ pods + WH, and PJ pods + DL + WH). The CM added in three combinations of co-digestion are equal to the amount of feed materials. If no significant biogas production was observed the experiments were terminated. These experimentations were tested under mesophilic condition (35±2 o C). All set of experiments were performed in duplicate. A small part of biogas is collected using gas bladder for biogas composition analysis. The biogas composition such as methane (CH 4) and carbon dioxide (CO 2) concentration is measured using gas chromatography. RESULTS AND DISCUSSION Characterization of the feed materials: Table I shows the characteristics of feed materials. The moisture content of the DL and GC are low compared to other materials. The materials in this study had a wide range of volatile solid (VS) content and total solid (TS). The PJ pods had high carbon content value of 42.06%. The other materials had the C/N ratio in the range of 15 to 30 which was the0 optimal range. Table II shows the characteristics of the influent used in the first and second experimentations. These tables also show the characte- ristics of the effluent once the digestion has ended in the reactor for each mixture. The digester influents had maintained the TS range between 5-15%. The WH had low TS value of 5.6% and DL had a high value of 15.1%. This variation is due to the moisture content present in the materials. First stage of experimentation: The first experiment seven different kind of materials are used to evaluate the AD process. Fig.3. shows the daily biogas production from different materials. From this graph, we observed that the peak biogas production of each material were achieved at different period of days. This is due to the degradability of the materials. The highest daily biogas production was recorded for CM on day 12 (2.82 l/kg/day). The CM had huge quantity of microorganism, so CM easily digested and gave the maximum daily biogas yield in low HRT period. Two peak biogas productions had recorded for PJ pods. Because this mixture contains the equal amount of CM and PJ pods. At first the CM had digested and secondly the PJ pods was digested. Similar kind of results was also recorded for the materials DL, GC, and WH. But the HRT period was varied for each material, based on the fiber, cellulose, and hemicellulose available in the materials. Lay had been described that the manure continuously declined by the use of bacterial in inoculum at initial fermentation are the reason of different peaks in the fermentation, while had not been degraded.
440 Prabhu, A.J. et al. Pak. J. Biotechnol. Fig.3. Daily Biogas production from different materials Therefore, after the first peak the fermentation liquid fell gradually. But the cellulose in straw was continuously degraded as the reaction continued. At initial fermentation, the organic acids produced and accumulated oxidized and decomposed into molecular hydrogen and acids by producing hydrogen bacteria and acid, then produced methane by methanogen, which led to the second peak (Lay et al., 2000). The daily methane production in parthenium showed significant fluctuations and maintained a low level. The cumulative biogas yield has been presented in fig 4. The much higher in total biogas production than other materials were scored by PJ pods. The highest biogas production has recorded 45.69 l/kg. The starting time of the biogas production in PJ pods was much longer than the CM and GC. The lowest biogas production was recorded for parthenium in the value of 20.12 l/kg. GC also gave the high yield (40.12 l/kg) per kg of feed materials. But comparing the digester size, one kg of GC required large size digester compared to the other materials digester. Because the weight and volume ratio of the GC are very low. The biogas composition of different materials was sketched in fig 5. The highest methane content (79.89%) was recorded in WH. The lowest methane content (13.45%) was recorded in parthenium. Fig.4. Cumulative Biogas production from different materials Fig.5. Biogas composition for different materials
Vol. 14 (3) 2017 Production of biogas.. 441 Fig. 6. Daily Biogas production for PJ pods+dl, PJ pods+wh, and PJ pods+ DL+WH Moreover, P gave the highest CO 2 content (66.5 7%) than other materials. The CO 2 content in the P was higher than the CH 4 content. So, this material was not feasible for anaerobic digestion process. The other materials were giving the methane yield in the range of 72 to 79%. The comparison between the cumulative biogas and methane yield shows that PJ pods could be a good material for anaerobic digestion. Second stage of experimentation: Based on the aforementioned information, it is clear that differrences existed between the materials. By considering the availability, ability to produce biogas, and pollutant behaviour of the materials, PJ pods, DL, and WH were the materials chosen for anaerobic co-digestion. Fig 6. shows the daily biogas production of PJ pods + DL, PJ pods + WH, and PJ pods + DL + WH. Among the three combinations, PJ pods + DL + WH had the highest daily gas production (2.99 l/kg/day) on 25th day. Biogas from the PJ pods + DL, PJ pods + WH reached their peak yield values at 2.28 and 1.85 l/kg/day on day 22 and 27, respectively. Due to the low concentration of bacteria, the lowest value of the daily biogas production was found in the initial days; bacteria concentration and their metabolism will increass the biogas production (Fantozzi et al., 2009). Two three combinations of materials. Because this mix- Fig. 7. Cumulative Biogas production for PJ pods+dl, PJ pods+wh, and PJ pods+ DL+WH Fig. 8. Biogas composition for PJ pods+dl, PJ pods+wh, and PJ pods+ DL+WH ture contain the equal amount of CM and materials. At first the CM had digested and secondly the materials were digested.
442 Prabhu, A.J. et al. Pak. J. Biotechnol. The total biogas productions by three combinations of PJ pods, DL, and WH at were shown in Fig. 7. PJ pods + DL + WH had the highest biogas yield at 65.41 l/kg after 60 days of digestion. In addition, the cumulative biogas production for PJ pods + WH was the lowest (56.56 l/kg) in the three combinations of co- digestion. The mixture PJ pods + DL (58.49 l /kg) with a methane content of about 72.71 % will gives the final biogas production. Fig.8. shows the biogas composition of the co-digestion materials. PJ pods + WH (78.74%) gives the maximum percentage of methane content. Moreover, the PJ pods + DL + WH mixture also gave the similar range of methane yield (75.89%). Therefore, considering the methane content and the total biogas production and in the biogas, the PJ pods + DL + WH mixture gave the maximum methane yield. CONCLUSION This study examined the biogas production of anaerobic digestion using seven different types of biomass materials and co-digestion of three mixture of PJ pods, DL, and WH. The first experiment PJ pods, CM, WH, and DL gave the better biogas yield. Comparing the two experimental test result shows that all the co-digestion mixture gave the highest yield than the different single materials. A good cumulative biogas production had achieved in co-digestion of PJ pods + DL + WH was found (65.41 l/kg). From this study, it was suggested that the co-digestion of biomass waste gave the good biogas production. REFERENCES Khaparde, S.A., Infrastructure for sustainable development using renewable energy technologies in India. Power engineering society general meeting, IEEE Pp. 1-6 (2007). Patel, S.R and K.N. Barot, Recent trends in renewable energy sources in India. International Journal of Research in Electrical Engineering 1(3): (2014). Leggett, J., R.E. Graves and L.E. Lanyon, Anaerobic Digestion: Biogas Production and Odor Reduction from Manure. Agricultural and Biological Engineering G 77. http://exten sion.psu.edu/natural-resources/energy/wasteto-energy/resources/biogas/projects/g-77 Weiland, P., Biogas production: current state and perspectives. Applied Microbiology and Biotechnology 85: 849 860(2010). Liu, C., X. Yuan, G. Zeng, W. Li and J. Li, Prediction of methane yield at optimum ph for anaerobic digestion of organic fraction of municipal solid waste. Bioresource Technology 99: 882 888 (2008). Alvarez, R and G. Liden, The effect of temperature variation on biomethanation at high altitude. Bioresource Technology 99: 7278 7284 (2008). Luste, S and S. Luostarinen, Anaerobic co-digestion of meat-processing by-products and sewage sludge Effect of hygienization and organic loading rate. Bioresource Technology 101: 2657 2664 (2010). Zhu, J., Y. Zheng, F. Xu and Y. Li, Solid-state anaerobic co-digestion of hay and soybean processing waste for biogas production. Bioresource Technology 154: 240 247 (2014). Wu, X., W. Yao, J. Zhu and C. Miller, Biogas and CH4 productivity by co-digesting swine manure with three crop residues as an external carbon source. Bioresource Technology 101: 4042 4047 (2010). Xu, F and Y. Li, Solid-state co-digestion of expired dog food and corn stover for methane production. Bioresource Technology 118: 219 226 (2012). APHA, Standard Methods for the Examination of Water and Wastewater, 18th ed. American Public Health Association, Washington, DC, USA (1998). Buchauer, K., A comparison of two simple titration procedures to determine volatile fatty acids in influents to waste-water and sludge treatment processes. Water SA 24(1): (1998). Lay, J.J., Modeling and optmiization of anaerobic digested sludge converting starch to hydrogen. Biotechnology Bioengineering 68:269 278 (2000). Fantozzi, F. Buratti and Cinzia, Biogas production from different substrates in an experimental Continuously Stirred Tank Reactor anaerobic digester. Bioresource Technology 100: 5783-5789 (2009).