Transport and fate of microplastics within wastewater treatment systems

Session: Microplastics in the Environment: Source, Fate, Impact, Detection, and Mitigation (1)

Mercedes Lavoy, University of Windsor, [email protected]
Jill Crossman, University of Windsor, [email protected]

Abstract

Microplastics (MP) enter Wastewater Treatment Systems (WWTS) through sewage and stormwater drainage systems. Preliminary studies have demonstrated that between 83 to 99.9% of MP may be removed during wastewater treatment. A significant proportion of plastics removed are believed to end up in the final product of the WWTS, the treated biosolids or ‘sludge’. In North America these biosolids are applied to crops designated for non-human consumption, thus redistributing MP from wastewater and stormwater to the environment. The treatment stages responsible for removal of MP, rate of input into biosolids, and efficiency of MP removal over time, has not yet been established. Since May 2018, monthly effluent samples have been collected at all treatment stages within two WWTSs; one servicing a combined, and the other a separated, sewage and stormwater system. Samples were sieved, dried at 60^oC, digested using Fenton`s reagent, and density separated using NaI. Resulting MP were isolated using an optical microscope, and confirmed through Raman analysis. The aim is to identify the treatment stage(s) responsible for the majority of MP removal and make recommendations for reducing MP entering biosolids. This research will advance efforts to prevent MP from entering the wider environment.