A critical review of microbial electrolysis cells coupled with anaerobic digester for enhanced biomethane recovery from high-strength feedstocks

Abstract

Anaerobic digestion (AD) is considered as a traditional method for biomethane recovery from high-strength waste and wastewater. The limitations of conventional anaerobic digestion processes include sluggish kinetics, process instability, and low methane yield. Recently, microbial electrolysis cell (MEC) has been demonstrated as a promising approach for enhancing biomethane recovery from various organic feedstocks. In recent years, a variety of hybrid anaerobic bioreactors coupling MEC and AD were employed to improve biomethane recovery and anaerobic treatability of various high-strength feedstocks. The MEC-AD integrated systems also exhibited better process stability than traditional anaerobic digesters by alleviating the accumulation of short-chain volatile fatty acids at higher organic loading rates, as well as mitigating the inhibitory effects of various toxic and refractory compounds. Firstly, this article provides a comprehensive performance review of the MEC-AD systems treating various high-strength (>8 g COD/L) substrates. Secondly, the implications of process parameters, energy efficiencies, and microbial community characteristics are discussed. Finally, valuable operational insights and future research needs are highlighted.

Graphical abstract

KEYWORDS:

• Anaerobic digestion
• MEC-AD system
• microbial electrolysis cells

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was supported by Strategic Partnership Grant (SPG) from Natural Sciences and Engineering Research Council of Canada (NSERC).