Biochar@MIL-88A(Fe) accelerates direct interspecies electron transfer and hydrogen transfer in waste activated sludge anaerobic digestion: Exploring electron transfer and biomolecular mechanisms

Weihang Xu; Lan Wu; Mengqi Geng; Junmei Zhou; Sai Bai; Duc Viet Nguyen; Rui Ma; Di Wu; Jin Qian

doi:10.1016/j.envres.2025.120810

Biochar@MIL-88A(Fe) accelerates direct interspecies electron transfer and hydrogen transfer in waste activated sludge anaerobic digestion: Exploring electron transfer and biomolecular mechanisms

Environ Res. 2025 Jan 9:268:120810. doi: 10.1016/j.envres.2025.120810. Online ahead of print.

Authors

Weihang Xu¹, Lan Wu², Mengqi Geng¹, Junmei Zhou³, Sai Bai¹, Duc Viet Nguyen⁴, Rui Ma¹, Di Wu⁴, Jin Qian⁵

Affiliations

¹ Research & Development Institute in Shenzhen, School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, China.
² Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia.
³ Sichuan Rongshi Environmental Protection Technology Co., Ltd, Chengdu, China.
⁴ Center for Environmental Energy Research, Ghent University Global Campus, Incheon, South Korea; Department of Green Chemistry and Technology, Ghent University, Ghent, Belgium.
⁵ Research & Development Institute in Shenzhen, School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, China. Electronic address: qianjin@nwpu.edu.cn.

PMID: 39793869
DOI: 10.1016/j.envres.2025.120810

Abstract

Adding additives exogenously is an effective strategy to enhance methanogenic activity and improve AD stability. Corn straw-based biochar@MIL-88A(Fe) (BM) was synthesized herewith and used as an exogenous additive to boost methane (CH₄) production. After adding BM at 250 mg/g WAS VS, the accumulative CH₄ production and maximum CH₄ yield increased by 1.2 and 1.9 times, respectively, with CH₄ comprising 88% of the biogas. BM accelerated electron transfer through its unsaturated sites and surface functional groups, while also enhancing metabolic functions for facilitating enzymatic activities and converting organic substrates. The abundance of syntrophic bacteria and methanogen were higher after BM addition. BM-mediated DIET and IHT pathways effectively oxidized propionate and butyrate, promoting methane generation. Higher expression of key genes involved in methane production correlated with shifts in microbial structure and increased CH₄ yield after BM dosage. The invention of BM may provide more solutions for addressing low energy recovery during AD.

Keywords: Anaerobic digestion (AD); Carbon compensation; Corn straw-based biochar@MIL-88A(Fe) (BM); Electron transfer paths; Meta-transcriptomic and metagenomic analysis; Methane production.