Insights into biodegradation behaviors of methanolic wastewater in up-flow anaerobic sludge bed (UASB) reactor coupled with in-situ bioelectrocatalysis

• DOI: 10.1016/j.biortech.2023.128835
• Publication Date: 2023-03-06T21:20:58Z
• Authors: Yijing Gao; Teng Cai; Jian Yin; Huan Li; Xinyu Liu; Xueqin Lu; Hongxia Tang; Weijie Hu; Guangyin Zhen
• Keywords: Bioreactors; Sewage; Methanol; Anaerobiosis; Wastewater; 7. Clean energy; Waste Disposal, Fluid; Methane; 6. Clean water

Granular sludge disintegration and washing out pose a challenge to up-flow anaerobic sludge bed (UASB) reactor treating methanolic wastewater. Herein, in-situ bioelectrocatalysis (BE) was integrated into UASB (BE-UASB) reactor to alter microbial metabolic behaviors and enhance the re-granulation process. BE-UASB reactor exhibited the highest methane (CH4) production rate of 388.0 mL/Lreactor/d and chemical oxygen demand (COD) removal of 89.6 % at 0.8 V. Sludge re-granulation was strengthened with particle size over 300 µm of up to 22.4%. Bioelectrocatalysis stimulated extracellular polymeric substances (EPS) secretion and formation of granules with rigid [-EPS-cell-EPS-] matrix by enhancing the proliferation of key functional microorganisms (Acetobacterium, Methanobacterium, and Methanomethylovorans) and diversifying metabolic pathways. Particularly, a high Methanobacterium richness (10.8%) drove the electroreduction of CO2 into CH4 and reduced its emissions (52.8%). This study provides a novel bioelectrocatalytic strategy for controlling granular sludge disintegration, which will facilitate the practical application of UASB in methanolic wastewater treatment.