A waste water treatment plant needed a pump for flotation sludge. It had to be installed in an existing basin, mainly used as a buffer zone by flooding. We chose a submersible BÖRGER Rotary Lobe Pump with a non-submersible drive. Because of changing water levels, we designed a pump unit with an extended shaft arrangement. For easy maintenance, the suction side is connected to the pipe system with a flexible hose and the discharge side can be separated through a jaw clutch coupling.