Bioelectrochemical treatment of olive oil mill wastewater using an optimized microbial electrolysis cell to produce hydrogen

A single chamber microbial electrolysis cell (MEC) was constructed to treat olive oil mill wastewater (OOMW) biologically and produce hydrogen simultaneously. To characterize the optimal MEC condition, the MEC was fed with synthetic wastewater (SW) having a phenol concentration of 250 mg l(-1). Therefore, the influence of different applied voltages and cathode materials was explored and the optimum condition for MEC was determined, which was when the stainless steel cathode was implemented and the external voltage of 0.6 V was supplied. Chemical oxygen demand (COD) removal of 62% and current density of 362 mA m(-2) were obtained for OOMW treatment, while COD removal of 73% and the current density of 274.4 mA m(-2) were attained for SW treatment in this MEC at 0.6 V. Hydrogen production rate was 0.045 m(3) H-2 m(-3)d(-1) for SW and 0.053 m(3) H-2 m(-3)d(-1) for OOMW. Furthermore, the coulombic efficiency and cathodic hydrogen recovery were 23% and 81%, respectively. Finally, MEC performance in terms of electrical current generation, wastewater treatment and hydrogen production was compared to some similar reported studies.