Microbial electrolysis cells (MECs) are an efficient technology for generating hydrogen gas from organic matters, but an additional voltage is needed to overcome the thermodynamic barrier of the reaction. A combined system of MEC and the aluminum-air battery (Al-air battery) was designed for hydrogen generation, coagulant production and operated in an energy self-sufficient mode. The Al-air battery (28 mL) produced a voltage ranged from 0.58 V to 0.80 V, which powered an MEC (28 mL) to produce hydrogen. The hydrogen production rate reached 0.19 +/- 0.01 m(3) H-2/m(3)/d and 14.5 +/- 0.9 mmol H-2/g COD. The total COD removal rate was 85 +/- 1%, of which MEC obtained 75 +/- 1% COD removal and 10 +/- 1% COD removal was achieved by in-situ coagulating process. The microorganisms removal of MEC effluent was 97 +/- 2% through ex-situ coagulating process. These results showed that the Al-air battery-MEC system can be operated in energy self-sufficient mode and recovered energy from wastewater with high quality effluent. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.