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URBANFILTER, special filters to prevent pollution from road microplastics

2.9.2021
URBANFILTER, special filters to prevent pollution from road microplastics

The Audi Environmental Foundation, together with the Technical University of Berlin and other partners, is developing filters for urban runoff to prevent particles from tyre wear and other environmentally harmful substances from being washed into sewers and bodies of water along with the rainwater.

Particles from tyre and asphalt wear are generated as a result of every vehicle ride. It is estimated that in Germany alone, 110,000 tonnes of it ends up on the streets in the form of microplastics every year; from there, it is scattered into the environment via the wind, or is washed by the rain via urban runoff and sewers into the soil, rivers, and oceans.

These environmentally harmful microparticles come not only from car tyres, but also bicycle tyres, the wheels of skateboards, and even shoe soles. “Unfortunately there’s no way to completely avoid them, but we can do something to ensure that less microplastic enters and pollutes the environment,” explains Rüdiger Recknagel, Managing Director of the Audi Environmental Foundation.

Polluting microplastics

The Audi Environmental Foundation is working with the Technical University of Berlin‘s Department of Urban Water Management and other partners – including filter manufacturers, software developers, and water utilities – to develop sediment filters for urban runoff. These devices are able to catch the contaminant particles as close as possible to their point of origin, even before they are washed into the sewer system by rainwater. The project was launched in September 2020 and will run for a period of three and a half years.

Modular filters

These special filters have a modular design and can therefore be perfectly adapted to different road situations, traffic volumes and other forms of pollution. At junctions or on winding roads, for example, the constant braking and restarting causes tyres to lose more wear particles than on an straight stretch of road.

In addition, we also want to capture as many other pollutants as possible that accumulate on and around streets, such as beverage cans and cigarette butts, which unfortunately often end up on the pavement, as well as natural particles such as sand, leaves and pollen from trees,” says Joachim Wloka, Greenovation project manager at the Audi Environmental Foundation and responsible for URBANFILTER.

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Three different levels

The sediment filters are divided into three different zones: street, sewer, and drain. “We are developing nine different modules for different road and traffic conditions, and up to three different modules can then be combined from this modular system to achieve the best result depending on the location,” explains Daniel Venghaus, a research associate at the Department of Urban Water Management at Technical University Berlin.

In the uppermost area (the street), this may be a special runoff channel or appropriate asphalt; in the middle layer – the sewer system – larger solids are filtered out, for example, with the aid of an optimised leaf basket or what is known as a filter skirt; while the lowest area – the drain – is where the fine filtration is performed.

Filtration and maintenance

For the fine filtration, a magnet module is currently being developed. “In our preliminary tests, magnets trapped particularly fine particles without clogging,” Venghaus notes. The modules are still, for the most part, in the planning stage; testing in real-world scenarios will start before the end of the year.

It goes without saying that the filters have to be maintained and emptied regularly – and this is where intelligent connectivity comes into play. Dedicated software analyses a wealth of different information for this purpose: from the street cleaning schedule and traffic volumes, to when rush hour takes place and the weather forecast, also taking into account additional details such as whether there are a lot of trees or whether people frequently walk their dogs along the road. “Based on all this information, we can predict each filter’s level of contamination and determine when the best time to empty it is. It’s basically the same idea as predictive maintenance, which is commonplace in the automotive industry,” Wloka adds.

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Proactive actions

The weather forecast plays a particularly important role in this intelligent network, and makes it possible to take proactive action. Depending on the time of year, storms and rain wash a particularly large amount of debris into street drains. The filters then clog more quickly and it is possible that unfiltered polluted water will be washed into rivers and lakes via the emergency spillway.

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

SourceAUDI AG

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