Hong Chen, Tao Yang, Zhiqiang Shen, Enzhe Yang, Ke Liu, Hong Wang, Jing Chen, Eli Hendrik Sanjaya, Sha Wu
Digestate recirculation is often considered an important way to improve system stability (system acidification, ammonia inhibition, hydrolysis limitations, etc.) and gas production performance. However, it is not clear how the promotion of biohythane production works in anaerobic co-digestion with digestate recirculation of rice straw (RS) and pig manure (PM). Two sets of laboratory-scale two-stage continuous stirred tank reactors were operated continuously for 95 d to investigate the performance of biohythane production in the first/second phase under mesophilic (M)/thermophilic (T) and digestate recirculation conditions. Firstly, biohythane was not produced by PM with RS under digestate recirculation. The main reasons were: 1) Digestive recirculation promoted the growth of hydrogenotrophic methanogenic bacteria; and 2) limitations in hydrolysis. Secondly, digestate recirculation has positive effects on the removal rates (removal rates of TS, VS, polysaccharide, protein and TCOD increased by 30.4%, 22.3%, 9.9%, 31.4%, and 11.9%, respectively) and energy yield (up to 68.7%). Finally, there was a higher abundance of hydrogen-producing bacteria (Fervidobacterium [44.9%] and Coprothermobacter [18.8%]) in T2, accounting for >80% of the total, and of which the huge hydrogen production potential cannot be ignored. The results provide new ideas for alleviating the energy crisis and developing green energy in the future. © 2022 Elsevier Ltd
Key Laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province, School of Hydraulic Engineering, Changsha University of Science & Technology, Changsha, 410004, China; Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province, Changsha, 410114, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environment Sciences, Beijing, 100012, China; Chemistry Department, Universitas Negeri, Malang, 65145, Indonesia