Constructing carbon-based materials loaded with MOFs to realize efficient anaerobic digestion of rural organic waste

The application of anaerobic digestion (AD) technology could convert rural organic waste (ROW) into renewable energy such as methane, which can help to mitigate the scarcity of fossil fuels and positively impact the global environment. However, the inhibition of ammonia nitrogen remains a significant obstacle to the methane production process with high concentrations of AD. Hence, in this study, three adsorption materials for ammonia nitrogen, namely FeMn-MOF, FeMn/MOF-CFs, and FeMn/MOF-CFC, were synthesized through distinct protocols. Their ability to mitigate the effect of ammonia nitrogen inhibition was investigated in a Continuous Stirred-Tank Reactor (CSTR) with total solid (TS) concentration of 10% under a semi-continuous operation of ROW digestion system. The results show that the addition of Metal-Organic Frameworks (MOFs) material substantially mitigated the inhibition of ammonia nitrogen and enhanced methane production. Compared with the control group, FeMn/MOF-CFC exhibited the best performance, with a 40.21% decrease in ammonia nitrogen concentration and 66.96 L/L-reactor cumulative methane production. Furthermore, the potential mechanisms underlying microbial community characteristics were explored, indicating that the addition of FeMn/MOF-CFC to AD provides the optimal enhancement of methane production. The addition of FeMn/MOF-CFC can enrich Methanosarcina, enhance the acetoclastic pathway for methane production, and increase the relative activity of coenzyme F420, achieving a 193.68% increase.