Undesired H2 sinks, including methanogenesis, are a serious issue faced by microbial electrolysis cells (MECs) for high-rate H2 production. Different from current top-down approaches to methanogenesis inhibition that showed limited success, this study found active harvesting can eliminate the source (H2) from all H2 consumption mechanisms via rapid H2 extraction using a gas-permeable hydrophobic membrane and vacuum. Active harvesting completely prevented CH4 production and led to H2 yields (2.62-3.39 mol of H2/mol of acetate) much higher than that of the control using traditional spontaneous release (0.79 mol of H2/mol of acetate). In addition, existing CH4 production in the control MEC was stopped once the switch to active H2 harvesting was made. Active harvesting also increased current density by 36%, which increased operation efficiency and facilitated organic removal. Energy quantification shows the process was energy-positive, as the H2 energy produced via active harvesting was 220 ± 10% of external energy consumption, and a high purity of H2 can be obtained.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Water Science and Technology
- Waste Management and Disposal
- Health, Toxicology and Mutagenesis