Product maturation and antibiotic resistance genes enrichment in food waste digestate and Chinese medicinal herbal residues co-composting.

ABSTRACT

The land application of food waste digestate (FWD) requires a composting process to improve its soil amendment performance and alleviate environmental risks. This study proposed co-composting of Chinese medicinal herbal residues (CMHRs) and FWD as a means to improve the maturation performance and investigated the evolution of antibiotic resistance genes (ARGs). Results demonstrated that CMHRs addition effectively accelerated the maturity of FWD composting to less than 35 days, remarkably removed its remaining antibiotics by 83.0% and promoted the formation of humification substances. However, both quantitative PCR and 16S rRNA sequencing analysis indicated that a significant enrichment of ARGs and mobile genetic elements including frA1, tetX, blaTEM, InuB-01, aadA2-02 and IntI-1 was observed via the co-composting of FWD and CMHRs. These results indicated that the land application of products obtained from FWD and CMHRs co-composting is at risk of spreading ARGs, although the composting process could be significantly improved.