Microplastic fibers discharged from wastewater treatment plants in Northern Ohio

Session: Microplastics in the Environment: Source, Fate, Impact, Detection, and Mitigation (2)

John Farver, Bowling Green State University, [email protected]
Blane Houck, Bowling Green State University, [email protected]

Abstract

Microplastic fibers (MPFs) typically <20 microns in diameter are released during cloths washing. Due to their fine diameter and high surface area, these fibers pose a threat to aquatic organisms as they can be taken into cells transferring contaminants. The purpose of this study is to quantify the release of MPFs by wastewater treatment plants (WWTPs). Samples of influent, effluent, and sludgecake were obtained at three WWTPs in Northern Ohio. Samples were also collected at two CSOs. The MPFs were extracted using ZnCl density separation in a sediment-microplastic isolation unit followed by digestion in H2O2 and vacuum filtration using quartz membranes (1.6 micron pores). The MPFs were identified using a cross-polarizing light microscope and quantified using both an ImageJ macro as well manual counting. The MPFs were chemically characterized using microRaman analysis and Spectral ID software. The comparison of MPFs in effluent to influent showed a decrease of 73-99% with effluent samples yielding average MPFs values of 111-393 fibers/liter for the different WWTPs. The average combined discharge of these three WWTPs is ~1000 million liters/day. Analysis of effluent from active CSOs yielded a range of 220-2167 MPFs/liter. Raman analysis of the fibers indicated >99% were polyester consistent with a cloths-washing source.