Chapter 10 - Occurrence and Fate of Microplastics in Wastewater Treatment Plants

Abstract

Microplastic (MP) contamination is ubiquitous in global waters and has become a potential health concern to the ecosystem and humans. As the link between the natural and anthropogenic water cycles, wastewater treatment plants (WWTPs) have been considered as the receptors of MPs from domestic and industrial wastewater and potential contributors of MPs to receiving waters and lands. In this chapter, the sampling, separation, and analytic procedures are summarized, and the classification, source, and transport of MPs in WWTPs are reviewed. Finally, the amounts of discharge of MPs from WWTPs are estimated. Most sampling and separation devices for MPs in wastewater samples are customized based on mechanical screening. The external biomass of MP particles is removed with pretreatment methods based on chemical digestion and density separation. After pretreatment, Fourier transform infrared and Raman spectroscopy are often used as common synergistic techniques for MP identification. In WWTP influent, microbeads and fiber debris are dominant MPs. Primary and secondary treatments in WWTPs can transport most MPs from wastewater to sewage sludge. Obviously, WWTPs are ineffective in eliminating MPs. Because substantial amounts of MPs are discharged along with effluent and/or sludge into receiving waters and/or lands, WWTPs have been confirmed as considerable point sources of MPs to the environment. It is highly desirable that new legislations and regulations are introduced to control the manufacture and application of MP-containing products that are eventually discharged to the wastewater treatment systems.