Intermittent polarization: A promising strategy for microbial electricity driven reduction of DOM toxicity in actual industrial wastewater

•Effluent DOM toxicity effectively reduced by 76.7 % at intermittent polarization.•Double bond equivalent (DBE) was an optimal parameter for assessing DOM toxicity.•High-DBE DOM compounds (≥ 8) were the key components responsible for DOM toxicity.•Polarization-microbe-DOM-toxicity links mediated intermittent polarization effects.•Advanced treatment should target high-DBE DOM over solely dissolved organic carbon. Dissolved organic matter (DOM) in actual industrial wastewater comprises various compounds that trigger toxicity in aquatic organisms; thus, advanced treatment for reducing DOM toxicity is urgently needed to ensure safe effluent discharge. Herein, we successfully reduced the toxicity of DOM in actual industrial wastewater without external chemical addition by applying intermittent polarization to electrochemical bioreactors. The bioreactor operated under intermittent polarization effectively reduced the toxicity of DOM by 76.7 %, resulting in the toxicity of effluent DOM (determined by malformation rate of zebrafish larvae) reaching less than 3.5 %. Notably, DOM compounds with high double-bond equivalence (DBE ≥ 8) were identified as the key components responsible for the toxicity of DOM through ultrahigh-resolution mass spectrometry analysis. Insight into microbe–DOM interactions revealed that intermittent polarization promoted the microbial consumption of high-DBE components of DOM by both affecting microbial composition (β = −0.5421, p < 0.01) and function (β = −0.4831, p < 0.01), thus regulating effluent DOM toxicity. The study findings demonstrate that intermittent polarization is a promising strategy for microbial electricity-driven reduction of DOM toxicity in actual industrial wastewater to meet the increasing safety requirements of receiving waters. [Display omitted]