To many urbanites, enjoying nature without leaving the city sounds like a pipe dream. Yet nature is already close at hand: If our rivers weren’t so dirty, they could be veins that reinvigorate the city. In Berlin, engineer Ralf Steeg has spent a decade fighting for a clean River Spree. And now, he seems to be getting close.

Berlin’s Eastern Harbor long ago ceased to be the German capital’s hub and key source of grains, coal, and bricks. Today, its quays play host to media companies, party boats, street food fairs, and even a swimming pool. A promising location for new ideas. And the perfect place for Ralf Steeg’s system, designed to capture and clean the 3.5-million-metropolises’ effluents before they end up in the river. As an added bonus, the construction’s surface also offers ample space for cafes or lounging.

smart magazine: Mr. Steeg – before we turn to your waste water cleaning system, let’s touch on a related issue: How do you think the city will change once you have realized your dream?

Ralf Steeg: It’s common knowledge that, over the past 20 years and around the world, people have rediscovered the appeal of rivers. They have noticed how pleasant it is to work or live near a river. This is what sparked our dream of once again having a clean River Spree – a stream where people can enjoy a few lengths after work, where kids learn how to swim, where flora and fauna return, and a river that once again becomes the city’s center and recreational area.

Ralf Steeg smart magazine
Ralf Steeg smart magazine
Ralf Steeg smart magazine
Ralf Steeg smart magazine
Ralf Steeg smart magazine

smart magazine: Some people are already taking a dip in the Spree – why would you recommend against it?

Ralf Steeg: The water is really quite dirty. After strong rainfall, the sewage treatment plants overflow and effluents reach the city’s water bodies untreated.

smart magazine: Sewage goes straight into the river?

Ralf Steeg: Exactly, but that’s not necessarily restricted to Berlin. Around the world, almost every metropolis – be it New York, London, or Tokyo – has a so-called combined storm water and sanitary sewage system. In Berlin’s city center, some of the sewage system dates back to the 19th century.

smart magazine: So, what exactly ends up in the river?

Ralf Steeg: It’s basically untreated waste water, e. g. from households, which contains literally anything that fits down a toilet and everything washed down from the streets. This includes cadmium from tire abrasion, which is especially harmful, plus heavy metal, renovation waste, unwanted medicine, and similar discards.

smart magazine: Let’s hear about your solution: What is the technical idea behind it all?

Ralf Steeg: We have developed a so-called modular system for storm water basins. In Berlin, this constitutes three 50-meter fiber glass pipes (with a 2-meter diameter) that can be attached to each other. The entire array can be installed in front of any waste water pipe outlet – in Germany, Africa, South America, or elsewhere. The moment the waste water arrives, it is captured and directed into a storage system. Afterwards, it can be cleaned on site and then fed back into the river.

smart magazine: Just how much can the entire system capture?

Ralf Steeg: The array has a capacity of 500,000 liters. On average, they are filled about 30 times a year.

smart magazine: Why did you opt for fiber glass?

Ralf Steeg: It lasts forever – and thus longer than the previously popular concrete. And it’s the same material used for the hulls of sailing boats.

“This is what sparked our dream of once again having a clean River Spree.”
Ralf Steeg

smart magazine: Living on the river is much in demand. How do you hide the fiber glass pipes from sight?

Ralf Steeg: Our set-up is invisible because everything goes on below the water surface. This brings us to another advantage: You can use the top and, for example, fill it with gardens or cafes – or simply lounge around on a sun deck and while the day away. Meanwhile, poorer cities and municipalities could refinance part of their system by renting these topside spaces, making the overall environmental measure much more affordable.

Watch our video “One fine day in Berlin” featuring Ralf Steeg, Original Unverpackt, and Philipp Geist.

All the images, incl. the header image: Markus Altmann