Improved hydrogen recovery in microbial electrolysis cells using intermittent energy input

Abstract

Microbial electrolysis cell (MEC) is a bioelectrochemical technology that can produce hydrogen gas from various organic waste/wastewater. Extra voltage supply (>0.2 V) is required to overcome cathode overpotential for hydrogen evolution. In order to make MEC system more sustainable and practicable, it is necessary to minimize the external energy input or to develop other alternative energy sources. In this study, we aimed to improve the energy efficiency by intermittent energy supply to MECs (setting anode potential = -0.2 V). The overall gas production was increased up to similar to 40% with intermittent energy input (on/off = 60/15sec) compared to control reactor. Cathodic hydrogen recovery was also increased from 62% for control MEC to 69-80% for intermittent voltage application. Energy efficiency was increased by 14-20% with intermittent energy input. These results show that intermittent voltage application is very effective not only for energy efficiency/recovery but also for hydrogen production as compared with continuous voltage application. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.