Effects of effluent recirculation on two-stage anaerobic digestion in treatment of biodegradable municipal solid waste
سال انتشار: 1402
نوع سند: مقاله ژورنالی
زبان: انگلیسی
مشاهده: 61
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شناسه ملی سند علمی:
JR_GJESM-9-0_003
تاریخ نمایه سازی: 4 مهر 1402
چکیده مقاله:
BACKGROUND AND OBJECTIVES: Advantages such as high stability and high biogas production when recirculating the effluent stream in two-stage anaerobic digestion systems have been demonstrated on a variety of substrates, but there is limited information regarding the use of this practice on organic municipal waste. Therefore, this study aimed to investigate how effluent recirculation affects the two-stage anaerobic digestion of biodegradable municipal solid waste.METHODS: Firstly, biodegradable municipal solid waste substrate was fermented under conditions of ۱۲ percent initial total solids and a temperature of ۳۶ degrees Celsius for ۵ days. After that, the substrate continued to be diluted using tap water or the effluent stream with a rate of ۲:۱. In the case of using the effluent stream, the experiment was further performed with dilution rates of ۳:۱, ۱:۱, and ۱:۲. Then, the liquid part was collected and pumped into the methane reactor at an organic loading rate of ۷.۶۴ grams of total solids per liter per day at ۳۶ degrees Celsius. The methane reactor was an up-flow reactor that contained both granular sludge and suspended sludge. The effectiveness of the experimental stages was evaluated through biogas production and chemical oxygen demand removal.FINDINGS: In the fermentative reactor, using the effluent stream to dilute solid-state feedstock helped keep the reactor stable at pH ۵.۵ without alkali addition. In the case of using tap water for dilution, it required a dose of ۱۱۵.۸ grams and ۷۵.۳ grams of sodium hydroxide per kilogram of volatile solids to attain pH conditions at ۶.۵ and ۵.۵, respectively. Maintaining the reactor at pH ۶.۵ increased the concentration of fermentation products compared to pH ۵.۵, including ۵.۹ percent total chemical oxygen demand, ۵.۵ percent soluble chemical oxygen demand, and ۱۰.۶ percent total volatile fatty acids. In the case of recirculating the effluent stream in the methane reactor, increasing the dilution rate from ۰.۵ to ۳.۰ resulted in a methane yield of ۲۲۷.۵-۲۷۸.۹ milliliter per gram of volatile solids and ۸۵-۹۳ percent chemical oxygen demand removal. The methane reactor’s best digestion performance was attained at recirculation rate ۲. Methane formation mainly occurred in granular sludge via the hydrogenotrophic pathway. Methane formation in suspended sludge occurred in a secondary manner, mainly via both the hydrogenotrophic and acetotrophic pathways. Among methanogen families, Methanobacteriaceae was found to have the highest relative abundance (۷.۵ percent in granular sludge and ۰.۸ percent in suspended sludge).CONCLUSION: Recirculating the effluent provided significant benefits, including the ability to stabilize the hydrolysis process and increase the methane yield. A recirculation rate of ۲ to obtain a total chemical oxygen demand of ۳۵.۲ grams per liter was the best condition for methanogenesis. Acetotrophic methanogens were better adapted to difficult conditions than hydrogenotrophic methanogens. The formation of methane mainly occurred in granular sludge via a dominant hydrogenotrophic pathway. Methane formation in suspended sludge occurred in a secondary manner, mainly via both the hydrogenotrophic and acetotrophic pathways. Among methanogen families, Methanobacteriaceae was found to have the highest relative abundance.
کلیدواژه ها:
نویسندگان
P.V. Dinh
Hanoi University of Civil Engineering, Department of Environmental Technology and Management, ۵۵ Giai Phong Road, Ha Noi, Vietnam
T. Fujiwara
Okayama University, Graduate school of Environmental and Life Science, Department of Environmental Science. ۳-۱-۱ Tsushima, Kita, Okayama, Japan
A.N. Peni
Bandung institute of technology, Bandung City, Indonesia
C.K. Tran
Hanoi University of Civil Engineering, Department of Environmental Technology and Management, ۵۵ Giai Phong Road, Ha Noi, Vietnam
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