Enhancing Biomethane Yield and Metabolic Pathways in Kitchen Waste Anaerobic Digestion Through Microbial Electrolysis Cell Integration

Qing Zhao, Heran Wang, Rufei Liu, Hairong Yuan and Xiujin Li ()
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Qing Zhao: Beijing Center for Environmental Pollution Control and Resources Recovery, Beijing University of Chemical Technology, Beijing 100029, China
Heran Wang: COFCO Joycome Foods Limited, Beijing 100020, China
Rufei Liu: Cucde Environmental Technology Co., Ltd., No. 36, Deshengmenwai Street, Xicheng District, Beijing 100120, China
Hairong Yuan: Beijing Center for Environmental Pollution Control and Resources Recovery, Beijing University of Chemical Technology, Beijing 100029, China
Xiujin Li: Beijing Center for Environmental Pollution Control and Resources Recovery, Beijing University of Chemical Technology, Beijing 100029, China

Energies, 2025, vol. 18, issue 7, 1-18

Abstract: This study developed a system (MEC-AD) by integrating a single-chamber microbial electrolysis cell (MEC) with anaerobic digestion (AD), aiming to enhance the conversion efficiency of kitchen waste (KW) into biomethane and optimize metabolic pathways. The performance and microbial metabolic mechanisms of MEC-AD were investigated and compared with those of conventional AD, through inoculation with original inoculum (UAD) and electrically domesticated inoculum (EAD), respectively. The results show that the MEC-AD system achieved a CH 4 yield of 223.12 mL/g VS, which was 31.27% and 25.24% higher than that of conventional UAD and EAD, respectively. The system also obtained total solid (TS) and volatile solid (VS) conversion rates of 82.32% and 83.39%, respectively. Furthermore, the MEC-AD system enhanced the degradation of soluble chemical oxygen demand (SCOD) and mitigated biogas production stagnation by reducing the accumulation of volatile fatty acids (VFAs) as intermediate products. Microbial metagenomics analysis revealed that the MEC-AD system enhanced microbial diversity and enriched functional genera abundance, facilitating substrate degradation and syntrophic relationships. At the molecular level, the system upregulated the expression of key enzyme-encoding genes, thereby simultaneously strengthening both direct interspecies electron transfer (DIET) and mediated interspecies electron transfer (MIET) pathways for methanogenesis. These findings demonstrate that MEC-AD significantly improves methane production through multi-pathway synergies, representing an innovative solution for efficient KW-to-biomethane conversion.

Keywords: kitchen waste; bioelectrochemical regulation; biogas yield; methanogenic metabolism pathway (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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