Preliminary study on the occurrence of microplastics in a local sewage treatment plant

Abstract

Recent studies have found that sewage treatment plants are potential source of microplastics pollution to its receiving freshwaters, which potentially affect freshwater ecosystems. This study aimed to investigate the occurrence of microplastics in sewage treatment plant, i.e., outlet of a primary clarifier and within an activated sludge system. A digestion method (oxidation digestion using Fenton's reagent coupled with wet peroxide oxidation technique) followed by microplastics extraction were attempted. Microplastics were detected, through instrumental characterizations, in all sewage samples in this study with microplastics found in the primary clarifier included polyamide, polytetrafluoroethylene and polyethylene terephthalate, while microplastics in the activated sludge system were polyamide, polystyrene and polyvinyl chloride. Results indicated that the sewage treatment plant successfully reduced microplastics from the primary clarifier to the activated sludge system by retaining bigger sizes of microplastics during early treatment stages of the system.