Mitigating antibiotic resistance genes in chicken manure composting through hydrothermal carbonization solution of sewage sludge

The disposal of the aqueous phase (HTAP) produced during the hydrothermal carbonization (HTC) of sewage sludge (SS), along with the potential environmental risks associated with the transmission of antibiotic resistance genes (ARGs) during livestock manure composting, represent two pressing challenges in environmental engineering. This study aimed to investigate the use of HTAP as a moisture regulator in chicken manure compost and its impact on the dynamics of ARGs. Metagenomic analysis identified a total of 686 ARGs in the compost, associated with 15 classes of antibiotics and multi-drug resistance. ARGs conferring resistance to aminoglycosides, tetracyclines, sulfonamides, and macrolides accounted for 17.88–25.59 %, 12.22–31.31 %, 5.23–27.56 %, and 9.22–28.65 % of the total ARG abundance, respectively. Bacillus and Actinomyces emerged as the dominant genera of drug-resistant bacteria. The application of HTAP resulted in a maximum reduction of 21.70 % in the total ARG abundance and a maximum decline of 19.34 % in the abundance of total mobile genetic elements (MGEs). Partial least squares path modeling revealed that HTAP had a positive influence on compost humification, which directly affected host microbial communities and indirectly suppressed the generation and dissemination of ARGs. These findings provide a novel approach for mitigating ARG levels in livestock manure compost.