Efficient hydrogen production from food waste leachate using single-chamber microbial electrolysis cell

The aim of this study was to develop an efficient strategy for enhancing H₂ production in the single-chamber microbial electrolysis cell (MEC) using food waste leachate as a substrate. Different pH (8.5, 9.5, 10.5, and 11.2), applied voltage (0.8, 1.2, 1.5, 1.8, 2.0, 2.2, 2.3, and 2.4 V) and negative pressure control (-50 kPa) were tested in the single-chamber MEC. Suitable pH adjustment could greatly promote electricity generation and H₂ production rather than negative pressure control. Under pH of 11.5 and 2.4 V, the maximum current density reached 121.9 ± 10.9 A/m³ with an average H₂ concentration of 91.9 ± 3.2% in a 1.2-L single-chamber MEC within 30 continuous cycles of operation (∼607 h), which was constructed with carbon brushes as the anode and stainless steel brushes as the cathode. The maximum H₂ production rate reached 853.2 ± 70.3 L/m³•d with an H₂ yield of 26.3 mmol•H₂/g•COD. The COD removal of 68.3 ± 6.8% and three-dimensional excitation-emission matrix spectra of the effluent in the MEC within 21 ± 3h indicated efficient organics degradation in the leachate. Our results should provide a promising way to enhance the H₂ production of MEC during leachate treatment.