Use of extracellular polymeric substances as natural redox mediators to enhance denitrification performance by accelerating electron transfer and carbon source metabolism

Xianbao Wang; Tiantian Chen; Chuyue Gao; Yili Xie; Anlong Zhang

doi:10.1016/j.biortech.2021.126522

Use of extracellular polymeric substances as natural redox mediators to enhance denitrification performance by accelerating electron transfer and carbon source metabolism

Bioresour Technol. 2022 Feb:345:126522. doi: 10.1016/j.biortech.2021.126522. Epub 2021 Dec 9.

Authors

Xianbao Wang¹, Tiantian Chen², Chuyue Gao², Yili Xie², Anlong Zhang³

Affiliations

¹ School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi Province 710021, China; China Light Industry Water Pollution Control Engineering Center, Xi'an, Shaanxi Province 710021, China. Electronic address: wangxianbao@sust.edu.cn.
² School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi Province 710021, China.
³ School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi Province 710021, China; China Light Industry Water Pollution Control Engineering Center, Xi'an, Shaanxi Province 710021, China.

PMID: 34896536
DOI: 10.1016/j.biortech.2021.126522

Abstract

Extracellular polymeric substances (EPS) extracted from waste activated sludge were used as endogenous redox mediator to enhance denitrification performance. The nitrate reduction rate increased 1.42-fold when EPS were added at 75 mg C/L (C represents total organic carbon). EPS addition decreased the charge transfer resistance and improved the electron transport system activity. The nitrate reductase and nitrite reductase activities improved by 29.7% and 25.4%, respectively. The activation energy of the system with EPS addition (25.82 kJ/mol) was 31.1% lower than that of the control group (37.49 kJ/mol). Besides, EPS could be used as electron carriers to accelerate electron transport; its primary role was similar to that of the quinone loop in the electron transfer chain. More importantly, EPS addition enhanced carbon source metabolism, which increased the available nicotinamide adenine dinucleotide yield to 1.21 times that of the control group, and thus promoted the denitrification performance of activated sludge.

Keywords: Denitrification; Electron transfer; Endogenous redox mediator; Extracellular polymeric substances; Glucose metabolism.

MeSH terms

Carbon
Denitrification*
Electron Transport
Electrons
Extracellular Polymeric Substance Matrix*
Oxidation-Reduction
Sewage

Substances

Sewage
Carbon