15.08.2025, Germany, Bottrop, North Rhine-Westphalia - Wastewater treatment at the Bottrop sewage treatment plant. The first stage of treatment at a sewage treatment plant involves mechanical cleaning (removal of coarse solids, sand and grease), the second stage involves a biological process (removal of nutrients using microorganisms) and the third stage is referred to as chemical-physical treatment (phosphate precipitation). In future, a fourth treatment stage will be necessary to remove trace substances, microplastics and medicines. The Emscher treatment plant in Bottrop is one of the most impressive structures on the Emscher. The four digestion towers are the largest of their kind, with a height of 54 metres and a total volume of 54,000 cubic metres. The clarification tanks have a total area of 58,000 square metres and treat 8,500 litres of water per second. Covering a total area of 147,000 square metres, the wastewater treatment process produces 190,000 tonnes of sewage sludge annually, which is recycled to power the plant. In the final stage of wastewater treatment, over seven million cubic metres of methane-containing sewage gas are extracted from the energy-rich sewage sludge. 00X250815D004CAROEX.JPG [MODEL RELEASE: NO, PROPERTY RELEASE: NO (c) caro images / Oberhaeuser, http://www.caro-images.com, [email protected] - In case of using the picture for any purpose, please contact the agency - the picture is subject to royalty!]