Electrokinetic technology enhanced the control of antibiotic resistance and the quality of swine manure composting

Aerobic composting is the primary way to utilize animal manure. However, the frequently detected antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in manure pose high risks to both the environment and human health. Based on our previous work on the effective removal of ARB and ARGs from water and soil using electrokinetic (EK) technology, it was introduced in traditional composting in this work to investigate its potentiality for quality improvement as well as antibiotic resistance control. The results showed that temperature, total nitrogen (TN), germination index, and humus index significantly increased in the EK treatment, while the abundances of ARB and ARGs decreased by 33.52–90.66 % and 68.60–85.24 % after 30-d composting, respectively. Moreover, the maturation period was reduced by 5 days compared to control. The electric field strongly affected the bacterial community structure. On one hand, the abundance of Chryseolinea increased and, accordingly, the nitrogen fixation capacity (the TN content) increased by 9.60 % in the EK treatment. Meanwhile, the increased abundance of Bacillus, Thermobacillus and Halocella accelerated the maturation and humification of the compost. On the other hand, the potential ARG host bacteria changed and especially that for sul1 decreased. In detail, the relative abundances of Actinobacteria and Firmicutes decreased by 45.89 % and 30.00 % in the EK treatment, respectively, which was closely associated with ARGs' removal. Functional prediction using PICRUSt revealed enhanced energy metabolism and membrane transport in response to antibiotic stress in the electric field. This study provides a potential solution to achieve both efficient and safe composting with the EK technology.