Material and microbial perspectives on understanding the role of biochar in mitigating ammonia inhibition during anaerobic digestion

Zhi-Jun Zhao; Xiao-Li Liu; Yi-Xuan Wang; Yan-Shan Wang; Jin-You Shen; Zhi-Cheng Pan; Yang Mu

doi:10.1016/j.watres.2024.121503

Material and microbial perspectives on understanding the role of biochar in mitigating ammonia inhibition during anaerobic digestion

Water Res. 2024 May 15:255:121503. doi: 10.1016/j.watres.2024.121503. Epub 2024 Mar 22.

Authors

Zhi-Jun Zhao¹, Xiao-Li Liu¹, Yi-Xuan Wang², Yan-Shan Wang³, Jin-You Shen⁴, Zhi-Cheng Pan⁵, Yang Mu⁶

Affiliations

¹ CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China.
² CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China; Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Industry and Information Technology, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China. Electronic address: yxwangg@mail.ustc.edu.cn.
³ School of Geographic Sciences, Nantong University, Nantong 226007, China.
⁴ Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Industry and Information Technology, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
⁵ Laboratory of Urban Wastewater Treatment Technology in Sichuan Province of Haitian Water Group Co., Ltd, Chengdu 610041, China.
⁶ CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China. Electronic address: yangmu@ustc.edu.cn.

PMID: 38537488
DOI: 10.1016/j.watres.2024.121503

Abstract

With the increasing adoption of carbon-based strategies to enhance methanogenic processes, there is a growing concern regarding the correlation between biochar properties and its stimulating effects on anaerobic digestion (AD) under ammonia inhibition. This study delves into the relevant characteristics and potential mechanisms of biochar in the context of AD system under ammonia inhibition. The introduction of optimized biochar, distinguished by rich CO bond, abundant defect density, and high electronic capacity, resulted in a significant reduction in the lag period of anaerobic digestion system under 5.0 g/L ammonia stress, approximately by around 63 % compared to the control one. Biochar helps regulate the community structure, promotes the accumulation of acetate-consuming bacteria, in the AD system under ammonia inhibition. More examinations show that biochar promotes direct interspecies electron transfer in AD system under ammonia inhibition, as evidenced by diminished levels of bound electroactive extracellular polymeric substances, increased abundance of electroactive bacteria, and notably, the up-regulation of direct interspecies electron transfer associated genes, including the conductive pili and Cytochrome C genes, as revealed by meta-transcriptomic analysis. Additionally, gene expression related to proteins associated with ammonium detoxification were found to be up-regulated in systems supplemented with biochar. These findings provide essential evidence and insights for the selection and potential engineering of effective biochar to enhance AD performance under ammonia inhibition.

Keywords: Ammonia inhibition; Anaerobic digestion; Biochar; Direct interspecies electron transfer; Meta-transcriptomic analysis.