Effect of gas atmosphere on hydrogen production in microbial electrolysis cells

Inert gas is often used in the deoxygenation of microbial electrolysis cells (MECs) to maintain growth and viability of anaerobes. However, the effects of the gas atmosphere on hydrogen production and microbial community of MECs are often neglected. Here, the performances and biotilm microbiomes of MECs pre-sparged with different gases were compared. MECs pre-sparged with argon gas (Ar) yielded more hydrogen (3.73 = 0.13 mol-H-2/mol-acetate) and a higher hydrogen production rate (2.99 +/- 0.17 L-H-2/L-reactor-day) than MECs pre-sparged with N-2 (3.41 +/- 0.13 mol-H-2/mol-acetate and 2.27 +/- 028 L-H-2/L-reactor-day, respectively). Microbiome analysis indicated that the relative abundance of Geobacter increased from 5925% to 77.79% when the gas atmosphere in MECs shifted from N-2 to Ar. Hydrogen production may have been catalyzed by nitrogenase from Geobacter and photosynthetic bacteria in MECs pre-sparged with Ar. These findings suggested that the gas atmosphere substantially influences the microbiorne of anode biofilms and Ar sparging is most effective for enhancing hydrogen production in MECs. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Comparing the performances and biotilm microbiomes of MECs pre-sparged with different gases revealed that MECs pre-sparged with argon gas (Ar) produced more hydrogen and had a higher hydrogen production rate than those pre-sparged with N-2. The relative abundance of Geobacter increased significantly when the gas atmosphere was switched from N-2 to Ar in MECs, indicating a potential catalytic role in hydrogen production. The findings suggest that the gas atmosphere has a substantial influence on the microbiorne of anode biofilms, with argon sparging being most effective for enhancing hydrogen production in MECs.