Designed for 80,000 residents: Foreman Michael Keller (second from right) guides you through the sewage treatment plant.
© ron
Water is not only the source of life, it can also contribute to the spread of diseases. This makes it all the more important to keep water as clean as possible. How wastewater is cleaned in Mühlenstadt and why researchers from TU Darmstadt see a virus early warning system in sewage treatment plants, participants of the Days of Industrial Culture found out on a tour through the complex in Mühlheim’s north-west, organized by the history association.
Mühlheim – The sewer network stretches from the Main to the Hainäcker industrial park and the DHL parcel center there, transporting 5.5 million cubic meters of wastewater from the towns of Obertshausen and Mühlheim to the sewage treatment plant on Rumpenheimer Strasse. There, the contaminated water flows through eight stations until it can flow almost cleanly into the Main, explains Jens Wiesmann, managing director of the wastewater association Untere Rodau, which has been operating the wastewater treatment plant since 2010. What remains during the cleaning process are, among other things, 1,600 cubic meters of sewage gas, which is produced when the sewage sludge decays and which is used to operate a combined heat and power unit. As a result, 52 percent of the power requirement on the plant could be covered last year, reports Wiesmann. There are also 3,000 tons of sewage sludge left over every year, which is disposed of in containers.
The biological-mechanical system on the Rumpenheimer is a complex system, from the screw pumping station at the entrance to a four-meter deep basin for biological cleaning, to the secondary clarifier, the last station before the drain into the Main. The complex has been in operation since 1966, the last major structural changes were made in 1994. The sewage treatment plant is designed for 80,000 residents, and the wastewater from around 75,000 people is currently being treated there, Wiesmann explains.
Managing director emphasizes: “We are prepared for such events”
Heavy rain events like last Sunday, when 48 millimeters of water per square meter poured from the sky, are intercepted by a dam canal connected in front of the system and a buffer basin, which together can hold around 8,000 cubic meters of wastewater. “We are prepared for such events”, emphasizes managing director Wiesmann. Only in the exceptional case that both basins would have flooded, wastewater would flow untreated into the Main.
Dr. Claus Spahn from the history association, who has been organizing events in Mühlheim for the Days of Industrial Culture for twelve years, reminds us that mankind has been dealing with the disposal of wastewater for thousands of years. Romans and Greeks already had canal systems, knowledge was lost in the Middle Ages. Sewer networks? Feces, urine and rubbish were simply dumped on the streets in the dark ages – a breeding ground for pandemics such as cholera and plague. Unthinkable today. And yet it is currently still difficult to get the water completely clean, reports foreman Michael Keller, who has been working on the system for 30 years.
Investment that would be reflected in higher wastewater charges
Dr. Laura Orschler from TU Darmstadt. Such monitoring brings to light trends and increases in the concentrations of coronaviruses in wastewater. In addition, mutations can be detected earlier than with clinical samples. Cleaning systems that are better able to filter multi-resistant germs or microplastics are still in their infancy and accordingly have a high cost factor, says Wiesmann. An investment that would make itself felt through higher wastewater charges. That, in turn, would be a source of anger for citizens. (By Ronny Paul)
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