Enhanced methane production in microbial electrolysis cell coupled anaerobic digestion system with MXene accelerants

Accelerants can improve the anaerobic performance of a microbial electrolysis cell coupled anaerobic digestion (MEC-AD). MAX phase titanium aluminum carbide (MAX), multilayer Ti3C2TX MXene (ML-MXene) and few-layer Ti3C2TX MXene (FL-MXene) were utilized as accelerants for MEC-AD to promote CH4 production and CO2 reduction at a voltage of 0.6 V. The highest CH4 yield (358.7 mL/g VS) and the lowest CO2 yield (57.4 mL/g VS) relative to the control group (170.6 and 125.1 mL/g VS) were obtained in MEC-AD with ML-MXene (0.035 wt%). The digestates of MEC-AD with 0.035 wt% ML-MXene have superior thermal stability (40.9%) and total nutrient content (42.1 g/kg). The ML-MXene enhanced the abundances of Methanosarcina and Methanobacterium. This work highlights the possible role of MXene in promoting methanogenesis. These important findings provide a novel avenue for the development of MXene accelerants for MEC-AD systems.