Enhancement of methanogenic activity in anaerobic digestion of high solids sludge by nano zero-valent iron

• Published in: The Science of the total environment Vol. 703; p. 135532
• Main Authors: Zhou, Jun, You, Xiaogang, Niu, Baowei, Yang, Xiaoqi, Gong, Lei, Zhou, Ying, Wang, Jin, Zhang, Haonan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.02.2020
• Subjects: Anaerobiosis; Bioreactors; Extracellular polymeric substances; Fatty Acids, Volatile; Hydrogen; Hydrogen evolutional corrosion; Iron - chemistry; Methane - metabolism; Methane production; Microbial community; Sewage; Volatile fatty acids; Extracellular polymeric substances; Methane production; Volatile fatty acids; Hydrogen evolutional corrosion; Microbial community
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.135532

This study evaluated the effects of nano zero-valent iron (NZVI, 50 nm) on anaerobic digestion of high solids sludge (10 ± 0.5%). Compared to the blank group without NZVI, the group with NZVI at all levels (10, 20 and 30 mM) played a driving role in methane production. The maximal methane production was increased by 37.5% in the group of 30 mM NZVI. The dynamic changes of hydrogen content and VFAs showed that rapid hydrogen evolutional corrosion of NZVI made lower hydrogen partial pressure in the later stage, which was more conducive to conversion of propionic acid. The microscopic analysis indicated that NZVI could flocculate and adsorb on the extracellular polymeric substances (EPS) around the anaerobic microorganisms, protecting most active microbial cell membrane from contact damage. On the other hand, some decaying microbial cells membrane could be destroyed by NZVI and intracellular substances would be released due to the reduction of EPS. [Display omitted] •NZVI significantly enhanced the anaerobic digestion performance of high solids sludge.•The effect of hydrogen evolutional corrosion rate of NZVI and ZVI to conversion of propionic acid was investigated.•The effect of EPS after NZVI exposure in the high solids sludge was elucidated.•Variation of microbial community and metabolic pathways after NZVI addition were explored.