Hydrogen Production and Wastewater Treatment in a Microbial Electrolysis Cell with a Biocathode

The broad application of microbial electrolysis cells (MECs) requires a system characterized by low cost and high operational sustainability. Biocathode MECs, which only require bacteria as the cathode catalysts, can satisfy these demands and have attracted considerable attention in recent years. In this study, we have examined biocathode alternatives to the typical platinum cathode in a single-chamber, membrane-free MEC. This biocathode MEC has been used for simultaneous hydrogen production and wastewater treatment. The results showed that hydrogen production rates increased in response to an increase in voltage. At an applied voltage of 0.9 V, the biocathode MEC achieved a hydrogen production rate of 0.39 m3 m−3 d−1, with a current density of 134 Am−3, chemical oxygen demand (COD) removal of 90%, a coulombic efficiency of 63%, a cathodic hydrogen recovery of 37%, and an energy efficiency based on an electricity input of 67%. The biocathode demonstrated sufficient electrocatalytic activity and achieved a performance level comparable to that of the platinum cathode. Moreover, the substrate that was used to simulate wastewater in this study was efficiently treated by the MEC.