Microplastics in sewage sludge.

Microplastics enter the wastewater and thus into the sewage sludge through various sources. This study provides a first insight into the emergence of microplastics in sewage sludges from Austrian wastewater treatment plants. For this purpose, samples from 35 municipal wastewater treatment plants were examined. PU, PET and PP have been identified as dominant types of plastics. A link between population values in the catchment area of the sewage treatment plant and the number of microplastic particles could not be established. For plastic particles > 1 mm, a possible influence was determined by the duct system (mixing or separating system) or by the degree of urbanisation. Very high microplastic values are presumably due to industrial inductors. Overall, it can be assumed that a variety of factors are responsible for the amount and type of composition of microplastics in the sewage sludge.