Removal of nitrate from agricultural runoff in biochar electrode based biofilm reactor: Performance and enhancement mechanisms

Yinfeng Xia; Debao Lu; Yiting Qi; Han Chen; Yufeng Zhao; Yu Bai; Lifang Zhu; Nan Geng; Cundong Xu; Ertian Hua

doi:10.1016/j.chemosphere.2022.134744

Removal of nitrate from agricultural runoff in biochar electrode based biofilm reactor: Performance and enhancement mechanisms

Chemosphere. 2022 Aug:301:134744. doi: 10.1016/j.chemosphere.2022.134744. Epub 2022 Apr 27.

Authors

Yinfeng Xia¹, Debao Lu¹, Yiting Qi², Han Chen², Yufeng Zhao¹, Yu Bai¹, Lifang Zhu², Nan Geng³, Cundong Xu¹, Ertian Hua⁴

Affiliations

¹ Key Laboratory for Technology in Rural Water Management of Zhejiang Province, Zhejiang University of Water Resources and Electric Power, Hangzhou, 310018, China; College of Water Conservancy and Environmental Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou, 310018, China.
² College of Water Conservancy and Environmental Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou, 310018, China.
³ Key Laboratory for Technology in Rural Water Management of Zhejiang Province, Zhejiang University of Water Resources and Electric Power, Hangzhou, 310018, China; College of Water Conservancy and Environmental Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou, 310018, China. Electronic address: gengn@zjweu.edu.cn.
⁴ Key Laboratory for Technology in Rural Water Management of Zhejiang Province, Zhejiang University of Water Resources and Electric Power, Hangzhou, 310018, China.

PMID: 35489461
DOI: 10.1016/j.chemosphere.2022.134744

Abstract

A biochar electrode based biofilm reactor was developed for advanced removal of nitrate from agricultural runoff. The corn-straw (Zea mays L.) biochar formed at 500 °C has an adsorption capacity of NO₃^--N up to 2.659 mg g^-1. After 45-day start-up phase, the removal efficiency of nitrate reached 93.4% when impressed current was 20 mA, hydraulic retention time was 12 h and chemical oxygen demand/total nitrogen (C/N) ratio was 0.56 without additional carbon source. In comparison, neither electrochemical reduction alone nor microbial denitrification alone could obtain the ideal nitrate removal efficiency. The results implied that bio-electrochemical reduction was the main way of nitrate removal in the biofilm electrode reactor (BER). The denitrification efficiency of 88.9% could still be obtained when C/N = 0. It is because biochar can significantly promote the utilization efficiency of cathode electrons by microorganisms. Thus, biochar is a promising electrode material, which provides a new idea for the optimization of BER.

Keywords: Agricultural runoff; Biochar electrode; Biofilm electrode reactor; Denitrification.

MeSH terms

Biofilms
Bioreactors
Charcoal
Denitrification*
Electrodes
Nitrates*
Nitrogen / chemistry
Nitrogen Oxides

Substances

Nitrates
Nitrogen Oxides
biochar
Charcoal
Nitrogen