Audi filtering out tire-wear, rubber ‘microplastics’ 

Ingolstadt, Germany – Audi Environmental Foundation (AEF) is developing filters to prevent tire & road wear particles (TRWPs) being transferred from urban runoff and sewer systems into the environment.

According to AEF, an estimated 110 kilotonnes/year of TRWPs end up on Germany’s streets in the form of ‘microplastics’, which can be washed by the rain via runoffs and sewers into the soil, rivers, and oceans.

As well as car tires, bicycle tires, skateboard wheels and even shoe soles produce these fine particles that are potentially harmful to the environment, noted the Audi agency. 

“But we can do something preventively to ensure that less microplastic enters and pollutes the environment,” said Rüdiger Recknagel, managing director of the AEF.

Working with the Technical University of Berlin’s department of urban water management, filter manufacturers, software developers and water utilities, the foundation is developing sediment filters for urban runoff. 

Under the 42-month project, which was launched last September, the team has optimised filters to capture contaminant particles as close as possible to their point of origin – even before they reach the sewer system. 

The modular design can be adapted to different road situations, traffic volumes, and other forms of pollution: in stop-and-go traffic, for example, the constant braking and restarting causes tires to lose more wear particles than on an unobstructed straight stretch of road. 

The sediment filters are also divided into three zones: street, sewer, and drain, explains Daniel Venghaus, a research associate at the department of urban water management at TU Berlin. 

“We are developing nine different modules for different road and traffic conditions,” said Venghaus. “Up to three different modules can then be combined from this modular system to achieve the best result depending on the location.” 

In the uppermost, street area, this may be a special runoff channel or appropriate asphalt. Below this, in the sewer itself, larger solids are filtered out, for example, with the aid of an optimised filter skirt, while the lowest, drain area is all about fine filtration. 

“We’re currently testing a magnet module here,” says Venghaus. “In our preliminary tests, magnets trapped particularly fine particles without clogging.” 

The modules are still mostly at the planning stage, though the partners are planning to test them in real-world scenarios before the end of the year.

The devices will employ ‘intelligent connectivity’ to predict each filter’s degree of contamination and determine when the best time to empty them – taking account of weather event such as rain storms, which wash a particularly large amount of debris into street drains. 

“If the weather forecast predicts heavy rain after a prolonged dry spell, we’d be able to respond immediately and have street sweepers clean the road before the downpour,” said Venghaus

This, he noted, would prevent the particles from entering bodies of water and the filter could remain in use for longer.

Founded by Audi AG in 2009, the AEF supports projects that “unite technology and environmental conservation and explore eco-friendly technologies, contribute to environmental education, or advance the cause of biodiversity.”