Efficient hydrogen production in single-chamber microbial electrolysis cell with a fermentable substrate under hyperalkaline conditions.

[Display omitted] • Efficient H 2 production was realized in the single-chamber MEC at pH of 11.2. • H 2 yield was 7.72 mol H 2 / mol glucose with purity of 93.3 % under 1.6 V. • Acetate production from glucose fermentation was enhanced at pH of 11.2. • SAO-HM and HM were inhibited in the anodic and cathodic biofilms, respectively. Hydrogen production from food waste is of great significance for energy conversion and pollution control. The aim of this study was to investigate the glucose fermentation from food waste and hydrogen (H 2) production in the single-chamber microbial electrolysis cell (MEC) under hyperalkaline conditions. Single-chamber MECs were tested with 1 g/L glucose as substrate under different pH values (i.e., 7.0, 9.5, and 11.2) and applied voltages (i.e., 0.8, 1.2, and 1.6 V). With pH increase from 7.0 to 11.2, H 2 production with methanogenesis inhibition was significantly improved in the MEC. At pH of 11.2, the maximum current density reached 180 ± 9 A/m3 with the H 2 purity of 93.3 ± 1.2% and average H 2 yield of 7.72 ± 0.23 mol H 2 / mol glucose under 1.6 V. Acetate from glucose fermentation was the largest electron sink within 12 h. Methanobacterium alcaliphilum dominated the archaeal communities with the relative abundance of > 99.0% in the cathodic biofilms. The microbial communities and mcr A gene copy numbers analyses showed that high pH enhanced the acetate production from glucose fermentation, inhibited syntrophic acetate-oxidizing with hydrogenotrophic methanogenesis in the anodic biofilms, and inhibited hydrogenotrophic methanogenesis in the cathodic biofilms. Our results of hyperalkaline conditions provide a feasible way to harvest H 2 efficiently from fermentable substrates in the single-chamber MEC. [ABSTRACT FROM AUTHOR]