Performance of two-stage vegetable waste anaerobic digestion depending on varying recirculation rates

• Published in: Bioresource technology 2014-06, Vol.162, p.266-272
• Main Authors: Zuo, Zhuang, Wu, Shubiao, Zhang, Wanqin, Dong, Renjie
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Anaerobic digestion; Anaerobiosis; Biofuel production; Biofuels - microbiology; Biogas; Biogas production; Biological and medical sciences; Biological Oxygen Demand Analysis; Biological treatment of sewage sludges and wastes; Bioreactors - microbiology; Biotechnology; Effluents; Energy; Environment and pollution; Fatty Acids, Volatile - analysis; Fermentation; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Industrial applications and implications. Economical aspects; Methane - metabolism; Moisture content; Oxygen demand; Reactors; Recirculation rate; Refuse Disposal - instrumentation; Refuse Disposal - methods; Time Factors; Two-stage process; Use of agricultural and forest wastes. Biomass use, bioconversion; Vegetable waste; Vegetables; Vegetables - chemistry; Waste Products; Wastes
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2014.03.156

•The performance of VW anaerobic digestion under varying RR was investigated.•The appropriate RR could improve acidogenesis in acidogenic reactor.•Recirculation influenced COD and VS removal efficiency of the whole system.•Biogas production from the whole two stage system was improved by increasing RR. Vegetable waste, which characterized by high moisture content, was evaluated as a substrate for biogas production. The effects of recirculation rate (RR) on the performance of two-stage anaerobic digestion were investigated. The system was operated at an organic loading rate of 1.7gVS/L/d with varying RRs (0, 0.6, 1, and 1.4). Results demonstrated that volumetric biogas production rates in acidogenic reactor increased from approximately 0.27L/L/d to 0.97L/L/d, when pH is increased from approximately 5.1 to 6.7. These indicate that recirculation of alkaline effluent from the methanogenic reactor helps create a favorable condition for biogas production in the acidogenic reactor. The decrease in chemical oxygen demand (COD) concentrations from approximately 21,000mg/L to 6800mg/L was also observed in the acidogenic reactor. This condition may be attributed to dilution under recirculation. The dynamics between hydrolysis and methanogenesis under recirculation indicated that mass transfer capacity between two-stage reactors improved.