Improving the stimulation effect of electric current density (ECD) on microbial community is critical in designing and operating TDE-BAF. This study investigated the effect of ECD at 0.00, 4.08, 6.12, 12.20, 14.25, 16.30 and 20.20 A.m (2) on the removal performance, diversity and structure of microbial community in TDE-BAF. Results indicated that the ECD of 14.25 A.m(2) exhibited the highest COD, TOC and NH4+-N average removal rates with 93.33%, 91.26% and 93.87%, respectively; Under high ECD, especially exceeding 14.25 A.m(2), the inhibition of growth and activity because of plasmatorrhexis was in agreement with the sharp biomass decline; there was no significant relation between community richness and diversity and removal efficiency below optimum ECD, while above optimal ECD, it was just the opposite; Microbial communities mainly including Hydrogenophaga, Saprospiraceae_uncultured, Delftia, Enterobacter, Pseudomonas, Pseudoxanthomonas, and Nitrosospira and physicochemical properties well explained the excellent removal performance at the optimum ECD. (C) 2017 Elsevier Ltd. All rights reserved.