A novel bioelectrochemical system designed to manage wastewater for simultaneous bioelectricity and hydrogen production

Recently, there has been increasing interest in the simultaneous management of wastewaters for the sustainable supply of clean energy, hydrogen (H 2 ), and water. In this regard, we designed and evaluated a co-integrated microbial electrolysis cell (MEC) and microbial fuel cell (MFC) hybrid system for simultaneous H 2 production, wastewater treatment, and energy production in a single chamber. The effects of applied voltage, wastewater to inoculum ratio, temperature, and initial pH on H 2 production performance of the MEC reactor are evaluated. Under improved conditions (applied voltage of 1.0 V, wastewater-to-activated sludge ratio of 1:2, temperature of 35 °C, and initial pH of 7.0), the highest H 2 production rate in the MEC system is found as 26.5 mL/L. day In the MFC reactor, the maximum voltage of 215 mV with a power density of 4.66 W/m 3 and a COD removal efficiency of 29.7 % is obtained at a temperature of 55 °C and cow manure to distilled water ratio of 2:1. Moreover, the co-integrated MEC-MFC system is operated under fed-batch operating mode and the H 2 production at each cycle is obtained as 3.27-3.42 mL/L. day following fresh wastewater feeding. Consequently, these results show that co-integrated MEC-MFC systems for self-sustaining production of H 2 and wastewater treatment become feasible, providing a potential route for converting organic-rich wastewater into H 2 and as a sustainable energy source with waste management. • A novel bioelectrochemical system is designed to boost H 2 and energy production. • It results in H 2 production rate of 26.5 mL/L. day and recovery of 32.9 % in MEC. • It obtains the highest energy production of 215 mV and 4.66 W/m 3 in MFC. • An integration of MFC-MEC promotes effective H 2 production in fed-batch mode. • It offers a self-driven approach to produce green H 2 from wastewater.