A study towards minimising tylosin concentration and antibiotic resistance genes in tylosin fermentation dreg fertilizer

This study proposed a comprehensive treatment plan consisting of "high temperature + oxidant pre-treatment"before compost and "thermal treatment"after compost to realise the compost resource utilisation of tylosin fermentation dreg. The study revealed that the tylosin concentration in the dregs was reduced by 97.1% under the optimal pre-treatment conditions. Subsequently, high-temperature compost was performed by adding compost auxiliary materials and the content of tylosin in the compost material was below the detection limit (<1 mg/kg) after 15 days. During the whole aerobic fermentation process, 70.8% of tylosin removal in the compost material was contributed by microbial metabolism, 23.0% was caused by high-temperature destruction of the compost, and 5.4% was due to the natural decomposition of tylosin. Finally, the finished compost product was further thermal-treated at 130 °C for 2 h, which could destroy the antibiotic resistance genes and maintain the seed germination index of the obtained fertiliser >80%, indicating the low plant toxicity of the compost. Based on this information, the tylosin fermentation dreg composting comprehensive treatment scheme proposed in this study is a safe, efficient and feasible resource utilisation scheme for tylosin fermentation dreg.