Identification of microplastic pathways within a typical European urban wastewater system

Abstract

In recent years, thermoextraction/desorption‐gas chromatography/mass spectrometry (TED‐GC/MS) has been developed as a rapid detection method for the determination of microplastics (MP) mass contents in numerous environmentally relevant matrices and, in particular, for the measurement of polymers in water samples without time‐consuming sample preparation. The TED‐GC/MS method was applied to investigate a typical European municipal wastewater system for possible MP masses. Such investigations are important in view of the recent revision of the Urban Wastewater Treatment Directive. Four different representative sampling sites were selected: greywater (domestic wastewater without toilet), combined sewer, and influent and effluent of a wastewater treatment plant (WWTP). All samples were collected by fractional filtration. Filtration was carried out over mesh sizes of 500, 100, 50, and in some cases, 5 µm. Polyethylene (PE), polypropylene (PP), and polystyrene (PS) were detected in all samples, with the PE fraction dominating in all cases. Styrene‐butadiene rubber which serves as an indication of tire abrasion, was only found in the influent of the WWTP. The highest MP mass contents were found in the combined sewer, so MP can become a source of pollution during heavy rain events when the capacity limits of the effluent are reached, and the polluted effluent is released uncontrolled into the environment. Based on the studies, MP retention from the WWTP could be estimated to be approximately 96%. Few trends in polymer type or mass contents were detected within the different fractions of the samples or when comparing samples to each other.

Reduction in the Input of Microplastics into the Aquatic Environment via Wastewater Treatment Plants in Germany

“…TED-GCMS is a destructive method, so there is a lack of information related to the particle size. With thermoanalytical determination methods, collecting information about particle size distribution is only possible with increased sampling and measurement effort, as can be seen in [49], where all of the samples were collected by fractional filtration over mesh sizes of 500, 100, 50, and in some cases 5 µm. Basically, we assume that a small number of large particles overwhelm many small particles in terms of the mass balance and, correspondingly, a few small particles only slightly contribute to the mass [57].…”

Exposure protocol for ecotoxicity testing of microplastics and nanoplastics

“…The lower measurable limit for particle size is ~1 µm in Raman spectrometry, but smaller particles can be measured if they are agglomerated and the size of the agglomerates is >1 µm 14 . The fully automated thermal extraction desorption (TED)-GC/MS Protocol is suitable for routine measurement of MNPs with minimum absolute masses between 0.06 and 2.2 µg in the crucible 29 .…”