Hydrogen evolution in microbial electrolysis cells treating landfill leachate: Dynamics of anodic biofilm

This study investigates the potential opportunities of hydrogen evolution treating landfill leachate in a set of two microbial electrolysis cells (MEC-1 and 2) under 30 °C and 17 ± 3 °C temperatures, respectively. The system achieved a projected current density of 1000–1200 mA m⁻² (MEC-1) and 530–755 mA m⁻² (MEC-2) coupled with low cost hydrogen production rate of 0.148 L La⁻¹ d⁻¹ (MEC-1) and 0.04 L La⁻¹ d⁻¹ (MEC-2) at an applied voltage of 1.0 V. Current generation led to a maximum COD oxidation of 73 ± 8% (MEC-1) and 65 ± 7% (MEC-2) with ≥100% energy recovery. The system also exhibited a high hydrogen recovery (66–95%), pure hydrogen yield (98%) and tremendous working stability during two months of operation. Electroactive microbes such as Pseudomonadaceae, Geobacteraceae and Comamonadaceae were found in anodophilic biofim, along with Rhodospirillaceae and Rhodocyclaceae, which could be involved in hydrogen production. These results demonstrated an energy-efficient approach for hydrogen production coupled with pollutants removal.