Microplastics in Sewage Sludge of Wastewater Treatment

Wastewater treatment plants (WWTPs) have been regarded as vital sinks and sources of microplastics from urban waters to the environment. Microplastics could be removed and migrated to the sewage sludge in the WWTPs. The microplastics accumulated in sludge are documented to have different effects on sludge anaerobic treatment systems and create certain risks for surrounding organisms after land application and landfills of sludge. To understand the role of microplastics in the sewage sludge treatment and evaluate their potential risk for discharge, this chapter will 1) investigate the occurrence of microplastics in various types of sewage sludge including primary sludge, waste-activated sludge and dewatered sludge; 2) understand the role and mechanisms of microplastics in the sludge anaerobic treatment process; 3) discuss the potential risk of microplastics from sludge to soil and landfill; and 4) compare the microplastic removal from sludge with various sludge treatment technologies. The outlooks of microplastics in sewage sludge are then finally proposed.