Ion-exchange membrane bioelectrochemical reactor for removal of nitrate in the biological effluent from a coking wastewater treatment plant

• The IEMBER integrates ion diffusion with bioelectrochemical degradation
• The IEMBER is efficient in reduction of nitrate in the coking wastewater effluent
• The anion-exchange membrane prevents the poisoning effect from the toxic residuals

Bioelectrochemical reduction of nitrate using an electrode (i.e., cathode) as the electron donor represents a promising method for denitrification; however, this process suffers from the problem of being applied for treating real wastewater, because the cathodic bacteria are susceptible to poisoning by other components in the wastewater. Here we reported the concept of an ion-exchange membrane bioelectrochemical reactor (IEMBER) that integrates the transport of nitrate from a wastewater chamber through an anion-exchange membrane (AEM) with its bioelectrochemical reduction in a separate cathode chamber. Successful removal of nitrate in the biological effluent from a coking wastewater treatment plant was achieved, in good agreement with the obvious cathodic current observed in the IEMBER when its cathode was poised at a potential of − 0.50 V (vs. SCE). The AEM plays a crucial role in preventing the residuals in the wastewater chamber to enter the cathode chamber, thus avoiding their potential toxicity to the denitrifying bacteria.