Passavant® circular scrapers were used for the tank scraping of the 6 new intermediate clarifiers. The positive experiences, which had been made with Passavant® scrapers over decades, were taken into account in the design details of the new tender. The bridges, which extend over the entire diameter, are divided into two parts and are equipped with an anti-kink monitoring system in the middle. For reliable winter operation, the scrapers are driven by a positive drive with gear racks. The electrical supply is provided by a slip ring body which is connected to the on-site electrical system via the central structure. The measuring and automation technology is installed in stainless steel external switch cabinets on the scraper bridge installed. The scrapers run in continuous operation at a scraping speed of 3 cm/s. The entire delivery was carried out in 2 construction phases (4 scrapers + 2 scrapers are still pending), so that a complete safe operation of the entire plant was guaranteed during the renewal period.