Effects of enzymes on organic matter conversion in anaerobic fermentation of sludge to produce volatile fatty acids

Juanjuan Wan; Lijuan Zhang; Boyu Jia; Bo Yang; Zeliang Luo; Jiakuan Yang; Patrycja Boguta; Xintai Su

doi:10.1016/j.biortech.2022.128227

Effects of enzymes on organic matter conversion in anaerobic fermentation of sludge to produce volatile fatty acids

Bioresour Technol. 2022 Dec:366:128227. doi: 10.1016/j.biortech.2022.128227. Epub 2022 Nov 1.

Authors

Juanjuan Wan¹, Lijuan Zhang², Boyu Jia¹, Bo Yang¹, Zeliang Luo³, Jiakuan Yang⁴, Patrycja Boguta⁵, Xintai Su⁶

Affiliations

¹ School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong 510006, China.
² School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong 510006, China; School of Environment, South China Normal University, University Town, Guangzhou, Guangdong 510006, China.
³ College of Electro-mechanical Engineering, Zhuhai City Polytechnic, Zhuhai, Guangdong 519090, China.
⁴ School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
⁵ Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland.
⁶ School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong 510006, China. Electronic address: suxintai@scut.edu.cn.

PMID: 36332860
DOI: 10.1016/j.biortech.2022.128227

Abstract

Sludge hydrolysis is a vital step in anaerobic digestion of sludge. This study compared the efficacy of free versus immobilized enzymes at different concentrations in promoting sludge disintegration. Pretreatment with 1,000 mg/L immobilized enzymes was more efficient in promoting sludge disintegration than free enzymes at the same concentration. Under the optimized conditions, volatile fatty acids (VFAs) were produced at 10.6 g/L, accounting for 85 % of total soluble chemical oxygen demand. Improved VFA production was attributed to the release of large amounts of polysaccharides and proteins from the enzymatically pretreated sludge. Released organic matter are the substrates for VFAs generated by the determined microbial community of Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, and Chloroflexi. In this study, anaerobic fermentation was used to successfully convert organic matter in sludge into high-value-added VFAs. Therefore, this process can be selected as a strategy to reduce carbon emissions from wastewater treatment plants (WWTPs).

Keywords: Anaerobes; Enzymatic pre-hydrolysis; FTICR-MS; Microbial community analysis.

MeSH terms

Anaerobiosis
Enzymes, Immobilized* / metabolism
Fatty Acids, Volatile / metabolism
Fermentation
Hydrogen-Ion Concentration
Sewage* / microbiology

Substances

Sewage
Enzymes, Immobilized
Fatty Acids, Volatile