The Kirchbauna wastewater treatment plant purifies the entire wastewater of the Bauntal-Schauenburg association area. After a good 30 years of operation of the KLEIN screening drum, the mechanical sludge thickening system was renewed. In the existing building, a new belt thickener of the solidXdrain series was installed with a matching polymer treatment system of the solidXfloc type. The plant was installed on the existing foundations of the old plant, so that only minor adjustments to the periphery and structural conditions were necessary. Since the work had to be carried out during ongoing operation of the wastewater treatment plant, Sülzle Klein ensured continuous operational safety by means of a mobile sludge thickener.