Collaborative removal of microplastics, bacteria, antibiotic resistance genes, and heavy metals in a full-scale wastewater treatment plant

Plastics are used in large quantities in food packaging and industrial products in China, which results in ecological risks of microplastics (MPs) to the environment. In this study, the MPs' removal efficiency of a full-scale wastewater treatment plant (WWTP) and the internal interaction of microorganisms, antibiotic resistance genes (ARGs), and heavy metals with MPs were investigated. The dominant MPs in urban sewage were polyurethane (PU), acrylate copolymer (ACR), fluororubber, and polyethylene. MPs in wastewater were removed by WWTP with a total efficiency of 76%. The removal efficiencies of ACR, ethylene-vinyl acetate copolymer, polybutadiene, poly(tetrafluoroethylene), polystyrene, and polypropylene reached 100%. The highest concentration of MPs PU in the influent got a removal efficiency of 93.41%. The interactions between MPs, heavy metals, microorganisms, and ARGs involved adsorption, hydrogen bonds, coprecipitation, and polar interaction. Heavy metals and MPs formed larger aggregated particles, which were removed in the primary process. Heavy metals accumulated in sludge pose ecological risks to soil during landfill or compost to fertilizer. The release of MPs from WWTPs leads to accumulation in organisms and soil. It may affect the entire food chain and promote the transmission of ARGs in the environment, posing potential threats to the entire ecosystem.