BACKGROUND p-Chloronitrobenzene (p-CNB) is easily accumulated in the environment and subsequently is a threat to humans and the ecosystem. The anaerobic process as an important pathway for p-CNB degradation has a relatively low degradation rate. This study illustrated that the strain Pseudomonas fluorescens was evaluated as the biocatalyst for bioaugmentation to enhance the p-CNB removal in bioelectrochemical system (BES). RESULTS When the initial p-CNB concentration was 100 mg L-1, the p-CNB removal efficiency reached 100% at 12 h in BES with P. fluorescens. All the p-CNB removal efficiencies in BES were higher than that in anaerobic degradation and electrocatalysis. Meantime, the highest total organic carbon (TOC) removal efficiency was obtained at 89.8% after augmentation with P. fluorescens. During the bioaugmentation, microbial community analysis showed that the main abundance changes were in Pseudomonas, Romboutsia and Macellibacteroides. The cyclic voltammetry (CV) showed BES with bioaugmentation had the highest activity in reducing p-CNB and hydrogen evolution. Combined with intermediates analysis, bioaugmentation possibly stimulated nitro reduction and hydrodechlorination rate in p-CNB reduction. CONCLUSION These results demonstrate that BES with P. fluorescens bioaugmentation could serve as a potential treatment process for p-CNB removal. (c) 2019 Society of Chemical Industry