Pilot-scale investigation of carbon cloth as an additive for enhancing high-solids anaerobic digestion and mitigating antibiotic resistance

This study explored the use of carbon cloth amendment in a pilot-scale high solids anaerobic digestion (HSAD) system with percolate recirculation. The results showed that adding carbon cloth led to a 22% increase in methane production and a 39% improvement in the maximum methane production rate. Microbial community analysis suggested possible direct interspecies electron transfer-based syntrophy between Pseudomonas, Methanobacterium and Methanosarcina. The carbon cloth amendment also enhanced microbial richness, diversity, and evenness. In addition, cloth amendment could effectively reduce the total abundance of antibiotic resistance genes (ARGs) by 44.6%, mainly by inhibiting horizontal gene transfer (HGT), as shown by the significant decrease in the relative abundance of integrons (particularly intl1). The multivariate analysis further demonstrated the strong correlations of intl1 with most targeted ARGs. These findings suggest that carbon cloth amendment can promote efficient methaneproduction and attenuate the proliferation and propagation of ARGs in HSAD systems.