Toward a Better Understanding of the Contribution of Wastewater Treatment Plants to Microplastic Pollution in Receiving Waterways

摘要

Microplastics (1 μm–5 mm), are ubiquitous in daily‐use products and regularly end up in the wastewater. The mainpart of the wastewater is treated in wastewater treatment plants (WWTPs), which allow for at least partial removal ofmicroplastics. The present study aimed to understand the contribution of domestic wastewater to microplastic pollution inFlanders (Belgium) via two main discharge routes of microplastics: (1) the effluent, and (2) removed fractions. Furthermore theeffect of effluent discharge on the microplastic contamination in the waterway was studied in both surface water andsediment samples of upstream and downstream locations of the discharge from three WWTPs. On average,12.64 ± 20.20 microplastic/L entered a WWTP (10 μm–5 mm). The effluent contained on average 0.41 ± 0.91 microplastic/L,resulting in an average removal efficiency of 97.46 ± 2.33, which is comparable with various (non‐)European countries.Removal efficiencies are both polymer‐ and size‐specific, and data suggest that smaller particles are less efficiently removedfrom the wastewater, which also causes an increased input of smaller particles to the environment. The sludge is the mostefficient treatment process to remove microplastics. Despite the high removal efficiencies, still 1.11 × 10~7 ± 3.07 × 10~7 microplasticsend up in the nearby waterway daily. Nonetheless, based on the results gathered in the present study, this doesnot seem to impact the microplastic concentration in the waterway significantly. In summary, the present study offers aholistic approach in the research on the impact of wastewater on microplastic pollution in the ecosystem, integratingdifferent discharge routes and measuring the impact on environmental microplastic pollution.