Biocatalysed sulphate removal in a BES cathode

► Sulphate was reduced in a biocathode separated from organic matter oxidation. ► Minimum energy is required to poise the cathode at −0.26 V vs. SHE for sulphate removal. ► Sulphide was the main product from sulphate reduction. ► Sulphide was entrapped in the cathode due to high pH from the reaction.