Removal of tire wear from road runoff

The central objective of this work is to develop a sampling system for tire-wear emissions in urban areas to determine tire-wear hot spots and to develop decentralised technical filter solutions with a suitable test substance in order to reduce the emissions of tire wear into surface waters. First, the development of awareness of microplastics since the late 1960s is presented retrospectively. On the one hand, the increasing social relevance of the topic becomes clear, and on the other hand, the differences in the description of microplastics. Increasingly, analyses were no longer carried out using only optical methods, but were supplemented or even completely replaced by spectroscopic methods. Emission quantities into the environment for microplastics are compared with production quantities. For urban water management, combined sewer overflows and the direct discharge of road runoff can be identified as the most relevant entry points. For tire wear, the largest entry into the aquatic environment comes from the discharge of road runoff. In order to identify tire wear hot spots in urban areas, a monitoring approach using defined road sweeping samples has been developed. It was shown that up to six times more tire wear can be found in the curve area and up to three times more in the traffic light area than in the straight road. Based on this finding, a modular filter system was developed that allows decentralised cleaning of road runoff water. In order to test the developed prototypes, a test stand procedure established in Germany by the German Institute for Construction Technology (DIBt) was adopted. In particular, the Millisil W4 test material normally used was critically scrutinised and replaced by fractionated road sweepings for further tests. The modular filter system consists of nine filter modules for the road, gully and drain areas and can be individually configured. The tests show that the filters developed can retain up to 97% of the total TSS and up to 66% of the TSS < 63µm. The results of this work can help to significantly reduce the input of microplastics in general and tire wear in particular into our surface waters.