Burdened with maintenance, spare parts and high energy costs, a wastewater treatment plant (WTP) has replaced its multi-phase screw pumps with new rotary lobe pumps made by Börger.
Installed for a chamber filter press, the Börger pumps have been supplied as a twin-pack unit; two identical rotary lobe pumps, which are operated in series. Each Börger rotary lobe pump reportedly has its own frequency converter that allows speeds to be individually regulated.
When feeding the chamber filter press, operators at the WTP now have a choice between two phases: the pre-fill phase and the pressurised phase. During the pre-fill phase, large quantities of sludge are pumped at high speed into the chamber filter press to fill up its chamber.
As the solids in the sludge gather in front of the filter screens, the increasing filling level of the chamber increases the counter pressure in the chamber filter press. Using the frequency converter, the speed of the Börger pumps is then reduced accordingly.
In addition to improving the output of the application, the new rotary lobe pumps are said to have reduced energy costs, and are also easier to service with their maintenance-in-place design.