Stepwise pH control to promote synergy of chemical and biological processes for augmenting short-chain fatty acid production from anaerobic sludge fermentation

WATER RESEARCH

卷:155

Article

Wang, Xu^1,2,3  Li, Yanbo^1,4  Zhang, Ya^5,6  Pan, Yi-Rong^1,4  Li, Lin^1,3  Liu, Junxin¹  Butler, David² 

[1] Chinese Acad Sci, Res Ctr Ecoenvironm Sci, Beijing 100085, Peoples R China

[2] Univ Exeter, Dept Engn, Ctr Water Syst, Coll Engn Math & Phys Sci, Exeter EX4 4QF, Devon, England

[3] Chinese Acad Sci, Res Ctr Ecoenvironm Sci, State Key Joint Lab Environm Simulat & Pollut Con, Beijing 100085, Peoples R China

[4] Univ Chinese Acad Sci, Beijing 100049, Peoples R China

[5] Univ Oklahoma, Dept Microbiol & Plant Biol, Inst Environm Genom, Norman, OK 73019 USA

[6] Univ Oklahoma, Sch Civil Engn & Environm Sci, Norman, OK 73019 USA

关键词: Waste activated sludge;    Fermentation;    Short-chain fatty acids;    Stepwise pH control;    Microbial community structure;    Conceptual model;   

DOI  :  10.1016/j.watres.2019.02.032

来源: Elsevier

【 摘 要 】

Although sludge-converted short-chain fatty acids (SCFAs) are promising feedstocks for biorefineries, it remains challenging to maximise SCFA production by enhancing synergies between chemical/biological hydrolysis and acidogenesis processes while employing a balanced composition of microbial communities to counteract methanogenesis. Herein, stepwise control of fermentation pH and chemical/microbiological composition analysis of fermented sludge were used to probe the underlying mechanisms of SCFA production. Fermentation at pH 11 during the first three days promoted both chemical and microbial hydrolysis of sludge proteins and provided a niche for Anaerobrancaceae sp. to transform soluble protein into SCFAs. When pH was decreased from 11 to 9, Acinetobacter, Proteiniborus, Proteiniclasticum, and other acetogens became predominant and stayed significantly more active than during first-stage fermentation at pH 11, which benefited the acidification of hydrolysed substrates. Further assays indicated that early-stage sludge fermentation at pH 11 decreased the total amount of methanogenic archaea and hence reduced the amount of SCFAs consumed for methane production. Thus, the use of stepwise pH control for sludge fermentation allowed one to establish process synergies, facilitate chemical and biological hydrolysis, inhibit methanogens, and promote the growth of acidifying bacterial communities, which resulted in efficient SCFA production from sludge. (C) 2019 Elsevier Ltd. All rights reserved.

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