The team analyzed the degradation of microplastic in their home river. They found out, that even after 30 days of treatment through contact with the microorganisms in the sewage sludge, the small plastic particles do not degrade completely. Even plastic polylactate, which is labelled as biodegradable, is particularly resistant to sewage sludge. Polyethylene terephthalate (PET for short) is the only material in which the sewage treatment promotes significant chain degradation. The outstanding team adressed a serious problem and worked on a scientifically advanced level.