Microplastic Types in the Wastewater System—A Comparison of Material Flow-Based Source Estimates and the Measurement-Based Load to a Wastewater Treatment Plant

Emma Fältström,Kristina Borg Olesen,Stefan Anderberg

doi:10.3390/su13105404

Emma Fältström, Kristina Borg Olesen + Show 1 more

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https://doi.org/10.3390/su13105404

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Abstract

Microplastics are omnipresent in the environment, and wastewater treatment plants (WWTPs) have been highlighted as a transport pathway. The aim of this study is to contribute to increased understanding of microplastic sources in wastewater and test the possibilities of source tracking. Previous research has focused either on estimating microplastic contribution from various sources or on quantifying occurrence based on measurements. In this paper, these two approaches are compared. Microplastic types detected in the influent to a WWTP in Sweden are compared with estimations of sources in the WWTP catchment area. The total load from the identified sources was estimated to 1.9–14 tonnes/year, and the measurement-based load was 4.2 tonnes/year. In general, there was a good agreement between the two approaches; microplastic types with large shares at the inlet also had large contributions in the source estimates. An exception was cellulose acetate, which was not found at the inlet despite a large theoretical contribution. Many uncertainties remain, which lead to large intervals for the source estimates. The comparison can give an indication into which part of the intervals is most likely. Investigating more WWTPs with different characteristics and including particle morphology will further increase the understanding of sources that contribute to the presence of microplastics in wastewater.

Highlights

Plastic is a versatile material that is widely used in society, but its use is connected to pollution problems [1]
A theoretical contribution of microplastic types from various sources to the Sjölunda wastewater treatment plants (WWTPs), Malmö, Sweden, was compared with measurement-based estimates at the WWTP, and the results show that there is an agreement between the two approaches
Microplastic types with a large share in the measurement-based estimates had a large share in the source estimations, with a few exceptions

Summary

Introduction

Plastic is a versatile material that is widely used in society, but its use is connected to pollution problems [1]. Microplastics have been reported in both marine [4] and freshwater environments [5]. They are found in urban wastewater and stormwater [6,7,8], and elevated levels have been reported outside of wastewater treatment plants (WWTPs) [9]. Microplastics research is still in its infancy, and research results are often uncertain and sometimes contradictory. This makes it difficult to develop a sufficiently reliable overview of sources and pathways that can be used as a basis for comprehensive and efficient abatement strategies

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