The effects of pH on sulfate pollutant removal, power generation and microbial community were investigated using a bioelectrochemical system, which built on acclimatized sludge with sulfate at different pHs. For the experiment, ethanol was used as the electron donor for the sulphate reduction. In the range of pHs between 2.5 and 10.5, the optimum condition for sulfate removal from wastewater is at pH 4.5 considering the removal efficiency, chemical oxygen demand and coulombic efficiency; the results were different from previous studies that neutral condition is suitable for sulfate-reducing bacteria to treat pollutants. According to microbial community analysis, Paludibacter sp. might play the most important role in sulfate removal at pH 4.5. Desulfuromonadaceae sp., Desulfobulbaceae sp. and Desulfovibrio sp. were inferred to make major contributions to power generation. These results could help to reduce the cost in treating acidic wastewater and assist in the optimization of sulfate-rich wastewater treatment.