Toxicity stress alleviation through cometabolism and lignite activated coke immobilization in bioelectrochemical systems

Abstract

Bioelectrochemical systems (BESs) are a technology that can biodegrade contaminants and generate electricity, yet their performance is largely constrained for industrial wastewater treatment due to toxic pollutants. The present study aimed to investigate the combined effects of cometabolism and lignite activated coke (LAC) immobilization (N-L-MFC) on alleviating the inhibitory impacts of coking wastewater and enhancing biodegradation. Improved degradation performance was achieved, showing that the removal of chemical oxygen demand (COD), total organic carbon (TOC) and ammonia nitrogen (NH4+-N) within 12 h was 91.7 %, 88.1 % and 72.1 %, respectively. Data analysis with the Haldane inhibition model revealed that N-L-MFC had good tolerance to high pollutants, and the inhibition concentration of organic and inorganic substances was 2.1 ∼ 6.4 times higher than that of cometabolism (N-MFC) or LAC packing (L-MFC). Separately, the cometabolism process minimized poisoning towards microorganisms by enhanced aromatic matter and inorganic biodegradation. LAC alleviated the toxicity of macromolecular and unsaturated groups by adsorption. The electrical properties indicate the resistance for electron transfer significantly relieved in N-L-MFC. From microbial community analysis, nontolerated electroactive bacteria Geobacter enriched in N-L-MFC indicate the positive succession of functional bacterial. Immobilized facultative bacteria such as Pseudomonas, Proteiniphilum, and Corynebacterium enriched on LAC involve in multiple metabolism process which also exerted synergistic degradation for aromatic organics, inorganics, and NH4+-N metabolism in biochemical processes. This research provides an efficient strategy for treating wastewater with recalcitrant contaminants by bioelectrochemical process.