Can digestate recirculation promote biohythane production from two-stage co-digestion of rice straw and pig manure?. (1st October 2022)

• Record Type: Journal Article
• Authors: Chen, Hong; Yang, Tao; Shen, Zhiqiang; Yang, Enzhe; Liu, Ke; Wang, Hong; Chen, Jing; Sanjaya, Eli Hendrik; Wu, Sha
• Is Part Of: Journal of environmental management. Volume 319(2022)
• Publication Date: 2022-10-01
• Subjects: Anaerobic co-digestion -- Digestate recirculation -- Rice straw -- Pig manure -- Biohythane; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2022.115655
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: 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. Graphical abstract: Image 1 Highlights: Anaerobic co-digestion with digestate recirculation produced no biohythane. Digestate recirculation improved system stability, removal rate, and energy yield. Digestive recirculation promoted hydrogenotrophic methanogenic bacteria growth. M1-T1 and T2-M2 were hydrolysis-limited. The thermophilic acid-producing phase showed strong hydrogen production potential.