As conserving water and maintaining high water quality become increasingly critical issues for South Africa, wastewater systems will need to perform more reliably and safely. According to Bennie Thiart, Grundfos sales director water utility South Africa, the Grundfos SE/SL range of wastewater pumps are now fitted with the Open S-tube® impeller for greater durability and reliable performance.
“As the level of solids in our wastewater rises, this innovative pump design can make wastewater plants and pump stations much less susceptible to stoppages and overflowing,” says Thiart. “Our design allows even stringy material like rags to be passed quickly through the pump without causing a blockage or shutdown of the motor.”
He highlights that wastewater treatment plants and pump stations operated by municipalities or industry can cause considerable environmental harm when they overflow due to pump stoppages. When there are unexpected disruptions to pumping, waste water can flow into rivers and wetlands – that leads to contamination of groundwater aquifers.
“We can expect stricter enforcement of environmental legislation, as South Africa’s water resources are currently under pressure,” he says. “Wastewater treatment plants, for instance, can no longer afford the risk of spillages.”
The Grundfos SE/SL range with its semi-open hydraulic design will equip these facilities for higher levels of performance and operational security. The first generation of these pumps has been well received in southern Africa since the early 2000s, he says, and the market is ready for these added features.
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“Our development of the latest generation technology first required extensive virtual simulation,” he says. “We then spent the past two years testing actual prototypes in the field and the results have been up to our expectations.”
Hydraulic performance tests on the SE/SL range have followed the ISO 9906 standards, among others, while clogging tests are conducted according to the methodology developed by the Technische Universität Berlin.
Critical to the design is the quick expulsion of solid material and objects from the pump, to avoid raising the torque to levels that will trip the motor. This functionality can be enhanced by fitting a guide vane to the pump.
Pump performance can be remotely tracked with a Grundfos monitoring and control system, which can also generate early warning signals for operators in case of any changes in the operation of the pumps.
“With their improved durability and reliability, these pumps certainly give operators of wastewater treatment plants more peace of mind,” says Thiart. “We also have a depth of in-house expertise – both locally and globally – to assist with pump station design and pump selection to ensure fit-for-purpose solutions.”