Do wastewater treatment plants act as a potential point source of microplastics? Preliminary study in the coastal Gulf of Finland, Baltic Sea

Abstract

This study on the removal of microplastics during different wastewater treatment unit processes was carried out at Viikinmäki wastewater treatment plant (WWTP). The amount of microplastics in the influent was high, but it decreased significantly during the treatment process. The major part of the fibres were removed already in primary sedimentation whereas synthetic particles settled mostly in secondary sedimentation. Biological filtration further improved the removal. A proportion of the microplastic load also passed the treatment and was found in the effluent, entering the receiving water body. After the treatment process, an average of 4.9 (±1.4) fibres and 8.6 (±2.5) particles were found per litre of wastewater. The total textile fibre concentration in the samples collected from the surface waters in the Helsinki archipelago varied between 0.01 and 0.65 fibres per litre, while the synthetic particle concentration varied between 0.5 and 9.4 particles per litre. The average fibre concentration was 25 times higher and the particle concentration was three times higher in the effluent compared to the receiving body of water. This indicates that WWTPs may operate as a route for microplastics entering the sea.

Sources and Fate of Microplastics in Urban Areas: A Focus on Paris Megacity

“…Generally, wastewater is highly contaminated with fibers with the average concentration being of 248 AE 109 fibers L À1 (mean AE SD, n ¼ 20) reaching a maximum of 473 fibers L À1 . In comparison, another study found similar values about 180 textile fibers L À1 [19]. Unlike fibers, fragments were only rarely collected, probably because of the low volumes of the samples (100-400 mL).…”

Microlitter in sewage treatment systems

“…households, industrial activities, sometimes also storm water contains microlitter particles. Microlitter has also been detected in waste water effluents from Swedish and Norwegian STPs (Magnusson, 2014;Magnusson and Norén, 2014;Magnusson and Wahlberg, 2014;Talvitie et al, 2015). This shows that STPs are an entrance for microlitter to the aquatic environment (McCormick et al, 2014;Yonkos et al, 2014).…”

Micro-and macro-plastics in marine species from Nordic waters

“…However, there are some published papers on findings within the water column (e.g. Talvitie et al, 2015;Gewert et al, 2017) as well as ingestion in biota such as seabirds (van Franeker, 1985;van Franeker et al, 2011), fish (Skóra et al, 2012;Foekema et al, 2013;Bråte et al, 2016;Rummel et al, 2016) and invertertes (Vandermeersch et al, 2015;Wójcik-Fudalewska et al, 2016). The current data ground is small, but there are several ongoing projects on plastics in Nordic waters which have a specific focus on plastic ingestion.…”