A strategy for enhancing anaerobic digestion of waste activated sludge: Driving anodic oxidation by adding nitrate into microbial electrolysis cell

作     者：Hong Peng Zhiqiang Zhao Hong Xiao Yafei Yang Huimin Zhao Yaobin Zhang 

作者机构：Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology) Ministry of Education School of Environmental Science and Technology Dalian University of Technology Department of Environmental Science College of Environmental Sciences Sichuan Agricultural University-Chengdu Campus 

出 版 物：《Journal of Environmental Sciences》 (环境科学学报（英文版）)

年 卷 期：2019年第31卷第7期

页      面：34-42页

核心收录：

学科分类：083002[工学-环境工程] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 08[工学] 

基　　金：supported by the National Natural Scientific Foundation of China(No.51578105) 

主　　题：Waste activated sludge Microbial electrolysis cell Nitrate Anodic oxidation Sludge reduction 

摘      要：Cathodic reduction of CO_2 and anodic oxidation of organic matters are crucial to methaneproducing microbial electrolysis cell(MEC) applied in anaerobic digestion of waste activated sludge. However, cathodic CO_2 reduction is usually restrained by slow metabolism rates of H_2-utilizing methanogens and low electron-capturing capacity of CO_2, which consequently slows down the anodic oxidation that participates to sludge disintegration. Herein, a strategy with adding nitrate as electron acceptor to foster electronic transfer between the anode and cathode was proposed to improve anodic oxidation. Results showed that the average efficiency of anodic oxidation in the nitrate-added MEC increased by 55.9%. Accordingly,volatile suspended solid removal efficiency in the nitrate-added MEC was 21.9% higher than that of control MEC. Although the initial cumulative methane production in the nitrateadded MEC was lower than that of control MEC, the cumulative methane production in 24 days was 8.9% higher. Fourier transform infrared spectroscopy analysis indicated that anodic oxidation of MEC with nitrate accelerated the disintegration of sludge flocs and cell walls. Calculation on current signal further revealed that anodic oxidation driven by cathodic nitrate reduction was the main mechanism responsible for the improved sludge digestion.