WWTP intensification

The WWTP is now a mechanical-biological one with simultaneous nitrification and denitrification, aerobic stabilization, mechanical sludge dewatering and chemical phosphorus elimination. Grit chamber and mechanically cleaned coarse bar screens were installed on the pipe bringing the sewage water to the WWTP. The grit chamber is emptied into a container using a hydraulic grapple bucket. Behind the bar screens, waste water flows through a storm-water inlet into a storm water tank. From there it is pumped for integrated rough pretreatment situated in the service building. The mechanically pre-treated waste water then flows gravitationally into the distribution building. The biological part consists of two circulating activated sludge lines with simultaneous denitrification and nitrification in the external annulus and a circular final settling tank. The excessive sludge is pumped into a sludge lagoon. Aerobically stabilized sludge is mechanically dewatered and the resulting pressed out sludge is then transported to a container. A 10 m3 above-ground double-walled tank for chemical elimination of phosphorus was installed in the WWTP. The reconstruction and intensification took place with the WWTP in operation, and with only a partial restriction of the operation. However, there was never any WWTP outage during the construction and the collected samples always met the set limits. A one-year trial run commenced on 1st July 2012.