Ingolstadt, Germany — A research foundation founded by Germany car maker Audi A.G. is developing filters it claims can prevent tire and road-wear particles (TRWPs) from being washed into sewer systems along with rain water.
According to the Audi Environmental Foundation GmbH (AEF), the traffic flow in Germany generates as much as 110,000 metric tons of TRWPs a year in the form of "microplastics" that can be washed by rain via runoffs and sewers into the soil, rivers and oceans.
While car and truck tires generate the most TRWPs, bicycle tires, skateboard wheels and even shoe soles produce these fine particles that potentially are harmful to the environment, the AEF said.
"But we can do something preventively to ensure that less microplastic enters and pollutes the environment," said AEF managing director Rudiger Recknagel.
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 optimized filters to capture contaminant particles as close as possible to their point of origin — before they reach the sewer system.
The modular design can be adapted to different road situations, traffic volumes, and other forms of pollution, the AEF said. 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, according to 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," Venghaus said. "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, or 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 optimized filter skirt, while the lowest, drain area is all about fine filtration.
"We're currently testing a magnet module here," Venghaus said. "In our preliminary tests, magnets trapped particularly fine particles without clogging."
The modules mostly are 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 rainstorms, 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," Venghaus said.
This, he noted, would prevent the particles from entering bodies of water and the filter could remain in use for longer.
Founded by Audi 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."