Advance in treatment of co-contamination of antibiotics and heavy metals from stock breeding

With the rapid development of stock breeding and aquaculture in China, antibiotics, which are widely used to prevent and treat diseases and protect the health of animals, are discharged into the environment, thereby posing a threat to the ecological environment and human health. The frequent use of antibiotics has also resulted in increased microbial resistance. Heavy metals, as feed additives, can accumulate in the environment and cause pollution. In this review, the use of antibiotics and heavy metals in breeding and the pollution in animal species and the ecological environment are elaborated. Additionally, the existing treatment technology of antibiotics and the research progress of combined antibiotic-heavy metal pollution are summarized. The coexistence of antibiotics and heavy metals leads to the persistent combined pollution of antibiotics and heavy metals in wastewater and sediments produced by breeding. The co-selection mechanism driven by heavy metals affects the transmission of antibiotic-resistance genes to a certain extent. At present, the removal of antibiotics is based on advanced oxidation treatment supplemented by biological and ecological treatments. Biological treatment mainly uses microbial degradation of antibiotics and the adsorption capacity of activated carbon, whereas ecological treatment achieves pollutant removal via plants and other coupling processes in constructed wetlands. Advanced oxidation processes can achieve an efficient removal effect in a short time; however, the actual application must maintain a balance between the removal effect and cost. In addition, research on the antibiotics removal effect of various methods in the presence of heavy metal ions is lacking. Future research should focus on the following aspects: 1) ecological treatment techniques for co-contaminated aquaculture wastewater, such as artificial wetlands; 2) phytoremediation of co-contaminated sediment, especially plant selection and cultivation optimization; and 3) application of a combination of biological and ecological treatment technologies in practice.