Document Type : Research Paper
Authors
- Mohsen Soleymani 1
- Vahid Jahangiri Boltaghi 1
- Mohammad Javad Sheikhdavoodi 1
- Zabihollah Mahdavifar 2
1 Department of Biosystems Engineering, Shahid Chamran University of Ahvaz
2 Department of Chemistry, Shahid Chamran University of Ahvaz
Abstract
Introduction:
Biogas, a product of anaerobic digestion of biomass resources, is one of the major renewable energies with the potential to replace fossil fuels. Anaerobic digestion is performed under specific conditions and according to a specific chemical process. Sugar cane is one of the most common sources of sugar and bioethanol production in the world. In the ethanol distillation process, large quantities of vinasse are produced. The direct consumption of vinasse as fertilizer has many environmental problems. Anaerobic digestion of vinasse is a potential solution to such environmental problems. Factors affecting the performance of an anaerobic digester can be classified into three main categories: (1) raw material characteristics, (2) reactor design, and (3) operating conditions. Among the operating conditions, temperature and pH are the most important parameters, so in this study, these two parameters were investigated.
Materials and Methods:
The main raw material was vinasse. Some other additives were used to alter its chemical properties. To have a proper substrate composition, the ingredients before loading into the digesters were evaluated for their chemical and physical properties, including pH, concentration and C/N ratio. The bovine rumen contents of 10% of the final volume of input material were added to supply methanogenesis bacteria as well as to modulate the (C/N) ratio.
The Total Solid Content (TS), Volatile Solid (VS) and Chemical Oxygen Demand (COD), were evaluated before and after digestion.
A series of batch reactor were used to perform the experiment. The experiment was carried out in a split plot design in a completely randomized design. The main and sub-factor was respectively temperature (at four levels of 30, 35, 40 and 45 ° C) and pH (at four levels of 6.8, 7, 7.2 and 7.4), and the experiment was performed in three replication.
To measure the volume of gas produced, a 50 ml water tank connected to the digester outlet as a U-tube was used. The amount of water movement in the U-shaped tube is an indicator of the volume of biogas produced. For better detection of water displacement, some color was dissolved in water. Passing the gas produced from the three-molar NaOH solution, its impurities (mainly carbon dioxide) were absorbed, and the resulting pure gas was re-measured using a U-shaped tube. Using the law of complete gases, the biogas volumetric index was converted to the standard gas volume and finally converted to values based on (ml/gVS) and the new values were analyzed by analysis of variance and mean comparison.
Results and Discussion:
Almost all main and interaction effects on all the factors studied were significant at the 1% probability level. The amount of gas produced increased with increasing temperature but with increasing pH, it first increased and then decreased. The amount of gas produced at 35, 40 and 45 °C was not significantly different. So because of economic and energy constraints, an operating temperature of 35 °C is recommended for anaerobic digestion of vinasse. The graph of the interaction of temperature and pH shows that at higher temperatures the rate of gas production increases with increasing pH. Although the highest gas volume was obtained at pH of 6.8 and 7.4, but the gas produced in the pH range of 7–7.2 was more pure. Therefore, the best combination of pH and temperature to produce the highest and purest gas is 7 and 35 °C, respectively. But since the vinasse produced in the alcohol factories has high temperature and therefore higher temperatures are possible, so 40 °C is also recommended.
It was also clearly observed that the smaller the volume of gas produced, the greater its purity.
The VS-R factor is also more sensitive to temperature changes than to pH changes. Thus, in anaerobic digestion of vinasse, pH control is more important than temperature control. VS-R performs best at pH 7. This factor was not significantly different at 35, 40 and 45 °C. Therefore, considering the cost of providing more heat at temperatures of 40 and 45 °C compared to 35 °C, 35 °C is the best temperature for manure production with the highest volatile organic matter removal.
The COD-R process was similar at all pHs. COD-R at pH 7 was higher at all temperatures than at other pHs. It was also significantly higher at 40 and 45 °C, compared to other temperatures. So like other factors, the best pH and temperature based on this factor are 7 and 40 °C, respectively.
Conclusion
According to all factors studied, the best pH and operating temperature of anaerobic digestion of sugar cane vinasse is 7 and 35 ° C, respectively. Another important conclusion to be drawn from this study is that changes in all parameters studied are affected by pH changes rather than temperature changes. Therefore, sufficient care must be taken to ensure that pH variations in the anaerobic digestion medium be very low and around the range proposed (about 7).
Keywords
- Baier, U. and Schmidheiny, P. 1997. Enhanced anaerobic degradation of mechanically disintegrated sludge. Water Science and Technology, 36 (11): 137–143.
- Balaguer, M.D., Vicent, M.T. and Paris J.M. 1992. Anaerobic fluidized bed reactor with sepiolite a support for anaerobic treatment of vinasse. Biotechnology Letters, 14 (5): 433-438.
- Budiyono, Syaichurrozi, I. and Sumardiono, S. 2013. Biogas Production Kinetic from Vinasse Waste in Batch Mode Anaerobic Digestion. World Applied Sciences Journal, 26(11): 1464-1472.
- , Syaichurrozi, I. and Sumardiono, S. 2014. Kinetic model of biogas yield production from vinasse at various initial pH: comparison between modified Gompertz model and first order kinetic model. Research Journal of Applied Sciences, Engineering and Technology, 7(13): 2798-2805.
- Chamy, R., Pizzaro, C., Vivanko, E., Schiappacasse, M.C., Jeioson, D., Poirrier, P. and RuizFilippi, G. 2007. Selected experiences in Chile for the application of UASB technology for vinasse treatment. Water Science and Technology, 56(2): 39–48.
- Christofoletti, C.A., Escher, J.P., Correia, J.E., Marinho, J.F.U., Fontanetti, C.S., 2013. Sugarcane vinasse: environmental implications of its use. Waste Management, 33: 2752–2761.
- Cortez, L., Freire, W.J. and Rosillo-Calle, F. 1998. Biodigestion of vinasse in Brazil. International Sugar Journal, 100(1196): 403-404, 409-413.
- Dooagooii, A., GhazanfariMoghaddam, A. and Fooladi, M. 2011. Investigation of kinetics and modeling of biogas production from the waste of rose water extraction of Damask rose. Iranian journal of Biosystems Engineering, 42 (1): 95-102. (In Farsi)
- Elbehri, A., Segerstedt, A., and Liu, P. 2013. Biofuels and the sustainability challenge: a global assessment of sustainability issues, trends and policies for biofuels and related feedstocks. Food and Agriculture Organization of the United Nations (FAO).
- Espinosa, A., Rosas, L., Ilangovan, K. and Noyola A. 1995. Effect of trace metals on the anaerobic degradation of volatile fatty acids in molasses stillage. Water Science and Technology, 32(12): 121-129.
- Janke, L., Leite, A. F., Batista, K., Silva, W., Nikolausz, M., Nelles, M., & Stinner, W. 2016. Enhancing biogas production from vinasse in sugarcane biorefineries: Effects of urea and trace elements supplementation on process performance and stability. Bioresource Technology, 217: 10-20.
- Kafle, G.K., Kim, S.H., Sung, K.I., 2012. Ensiling of fish industry waste for biogas production: A lab scale evaluation of Biochemical Methane Potential (BMP) and kinetics. Bioresour. Technology, 127: 326-336.
Leite, A., Janke, L., Lv, Z., Harms, H., Richnow, H.-H., Nikolausz, M., 2015. Improved monitoring of semi-continuous anaerobic digestion of sugarcane waste: effects of increasing organic loading rate on methanogenic community dynamics. International Journal of Molecular Science, 16: 23210–23226.
- Lio, C., Wachemo, A.C., Tong, H., Shi, S., Zhang, L., Yuan, H. and Li, X. 2018. Biogas production and microbial community properties during anaerobic digestion of corn stover at different temperatures. Bioresource Technology, 261(1): 93-103.
- Lv, Z., Hu, M., Harms, H., Richnow, H.H., Liebetrau, J., Nikolausz, M., 2014. Stable isotope composition of biogas allows early warning of complete process failure as a result of ammonia inhibition in anaerobic digesters. Bioresource Technology: 167, 251–259.
- Mariano, A.P., Dias, M.O.S., Junqueira, T.L., Cunha, M.P., Bonomi, A., Filho, R.M., 2013. Butanol production in a first-generation Brazilian sugarcane biorefinery: technical aspects and economics of greenfield projects. Bioresource Technology, 135: 316–323.
- Moosavi, Gh., Mahdavianpoor, M., Aghayani, A. and Poorakbar, M. 2017. Principles, design, construction and operation of biogas systems. First edition, Yarres Publishing House, Tehran, 9-15. (In Farsi)
- Moraes, S., Junqueira, T.L., Pavanello, L.G., Cavalett, O., Mantelatto, P.E., Bonomi, A. and Zaiat, M. 2014. Anaerobic digestion of vinasse from sugarcane biorefineries in Brazil from energy, environmental, and economic perspectives: Profit or expense. Applied Energy, 113(1): 825–835.
- Mota, V.T., Santos, F.S., Amaral, M.C.S., 2013. Two-stage anaerobic membrane bioreactor for the treatment of sugarcane vinasse: assessment on biological activity and filtration performance. Bioresource Technology, 146: 494–503.
- Safari, M., Abdi, R. and Adl, M. 2015. Investigating the extraction of biogas from rapeseed stem residues, rumen content and cow manure. Research in agricultural Mechanization and Systems (Agricultural Engineering Research), 16(65): 825-835.
- Speece, R. E. 1983. Anaerobic biotechnology for industrial wastewater treatment. Environmental Science and Technology, 17(9): 416A-427A.
- Suanon, F., Sun, Q., Mingyue, L., Xiang, C., Youchi, Z., Yijun, Y. and Chang-Ping, Y. 2017. Application of nanoscale zero valent iron and iron powder during sludge anaerobic digestion: Impact on methane yield and pharmaceutical and personal care products degradation. Journal of Hazardous Materials, 231(1): 47-53.
- Syaichurrozi, I., Budiyono and Sumardiono, S. 2013. Predicting Kinetic Model of Biogas Production and Biodegradability Organic Materials: Biogas production from Vinasse at Variation of COD/N. Bioresource Technology, 149(1): 390-397.
- Xie, S., Lawlor, P.G., Frost, J.P., Hu, Z. and Jhan, X. 2011. Effect of pig manure to grass silage ratio on methane production in batch anaerobic co-digestion of concentrated pig manure and grass silage. Bioresource Technology, 102(10): 5728- 5733.
- Yang, Y., Tsukahara, K., Yagishita, T., Sawayama, S. 2004. Performance of a fixed-bed reactor packed with carbon felt during anaerobic digestion of cellulose. Bioresource technology, 94(2): 197-201.
- Yilmaz, A., Sinan, U., Kocer, A. and Aygun, B. 2018. Factors affecting the production of biogas. International Journal of Scientific and Engineering Research, 9(5): 59-62.
- Cioabla, A. E., Ionel, I., Dumitrel, G. A., and Popescu, F. 2012. Comparative study on factors affecting anaerobic digestion of agricultural vegetal residues. Biotechnology for Biofuels, 5(1):
)