The sewage treatment plant in Putzhagen, Germany, requires large quantities of high-pressure compressed air for its exceptionally deep sedimentation tanks. Three ZB 130 VSD centrifugal compressors and two older single-stage screw compressors supply the compressed air for the biological process that occurs in the tanks.
Each year, the plant treats an average of between 6.5 and 7 million m3 of sewage water. "The biological process takes place in eight tanks that are sub-divided into four lines," explains Reinhard Schweinforth, Sewage Water Technician. The tanks are 10 m high with a water depth of 8.5 m. "These dimensions are unusual for sewage treatment plants," says Schweinforth. Tanks are normally 4 to 5 meters deep. The biological cleaning processes are carried out in the eight aeration tanks. The air required for this procedure is blown into the tanks from below via diaphragm tube aerators — an energy-intensive process that accounts for 40% of the plant's entire power consumption.