Bioelectrochemically Enhanced Anaerobic Digestion of Brewery Wastewater at Ambient Temperature: Performance, Methane Yield, and Energy Efficiency.

Abstract

Bioelectrochemically-enhanced anaerobic digestion (BEAD) has emerged as a promising approach to improve methane production and process stability during the treatment of high-strength industrial wastewater. In this study, a continuous upflow BEAD reactor was operated for 365 days to evaluate its performance in treating real brewery wastewater at ambient temperature (22-24 °C). The effects of organic loading rate (OLR; 1-7 g sCOD/L∙d), hydraulic retention time (HRT), and applied potential (1.2 V) on organic matter removal, volatile fatty acid (VFA) degradation, methane production, and energy efficiency were systematically investigated and compared with conventional anaerobic digestion (AD). The BEAD system achieved high chemical oxygen demand (COD) removal efficiencies (>92%) at OLRs up to 5 g sCOD/L∙d and demonstrated superior degradation of complex VFAs, particularly propionic and butyric acids. Methane yield increased with increasing OLR, reaching a maximum of 0.35 LCH₄/g sCODRemoved at an OLR of 7 g sCOD/L∙d. Compared with AD, BEAD enhanced methane production by 16-30% at higher OLRs while maintaining stable biogas quality (≈74-75% CH₄). Although shortening HRT at high OLRs reduced overall performance, BEAD consistently outperformed AD. The system exhibited high energy efficiency (~1000%), suggesting it could serve as a robust, highly energy-efficient candidate for brewery wastewater treatment in cold regions.