The significance of key operational variables to the enhancement of hydrogen production in a single-chamber microbial electrolysis cell (MEC)

Microbial electrolysis cell (MEC) is one of the promising and cutting-edge technologies for generating hydrogen from wastewater through biodegradation of organic waste by exoelectrogenic microbes. In the MECs, the operational parameters, such as applied voltage (Eap), anode surface area, anode-cathode distance, and N2/CO2 volume ratio have a significant impact on the hydrogen yield and production. In the present study, to enhance current and hydrogen production of MEC, the effects of key operational conditions on the MEC performance were extensively investigated. The optimal operating condition for hydrogen production in MECs was determined as: the optimum applied voltage of 1.1 V, anode surface area of 94 (cm2), anode-cathode distance of 1.5 (cm), and a N2/CO2 volume ratio of 4:1. With these optimum conditions, the maximum H2 volume, current density and hydrogen production rate (HPR) of MEC could be reached to 270.09 mL, 314.01 ± 2.81 A/m3, and 4.25 ± 0.55 m3 H2 /m3 d, respectively. The results obtained in this study imply that a systematic investigation of the key operational variables is an effective strategy to maximize the hydrogen production in single-chamber MECs.