Microplastics in sewage sludge.

Microplastics pass through various sources into the waste water and thus into the sewage sludge. This study provides an initial insight into the emergence of microplastics in sewage sludge from Austrian wastewater treatment plants. Samples from 35 urban wastewater treatment plants were examined. PU, PET and PP have been identified as dominant types of plastic. There was no correlation between population values in the waste water treatment plant catchment area and the number of microplastic particles. For plastic particles > 1 mm, a possible influence was detected by the sewer system (mixing or separation system) or by the degree of urbanisation. Very high microplastic values are probably due to industrial inductors. Overall, it can be assumed that a variety of factors are responsible for the amount and nature of the composition of microplastics in sewage sludge.