High-performance processing operations and wastewater management are critical. “When an effluent’s chemical make-up is highly corrosive, and it is generated in fluctuating intermittent volumes, these are the critical variables we work with to custom design a system that we know will work reliably,” says Stephen Cutting, Flygt Sales at Natal Pump Services.
The company recently successfully installed a specialised wastewater solution at an industrial site in Durban. The sump was engineered to receive intermittent drawdowns of highly corrosive effluent from the Equalisation (EQ), Upflow Anaerobic Sludge Blanket (UASB), and buffer tanks during scheduled maintenance activities. “These drawdowns create extreme variations in inflow — from low background seepage to sudden high-volume discharge events,” explains Cutting.
He says managing these fluctuations efficiently was the primary design challenge.
At the core of Natal Pump Services’ installation are two heavy-duty submersible pumps in special duplex stainless steel construction. Bissett says these particular pumps were selected for their capacity to handle high solids. Their cast duplex stainless steel construction provides the required robustness, and they are suitable for aggressive and corrosive effluent. Their ability to operate reliably under cyclical loading is another factor that favoured their selection.
The pumps are mounted on a guide rail arrangement that allows safe removal for maintenance without entering the sump. “This is a critical safety consideration in the confined-space environment,” says Bissett.
Because the sump receives periodic high-volume maintenance discharges, the control philosophy had to accommodate the following three conditions:
- Rapid level rise during tank drawdowns;
- Extended low-flow idle periods; and
- Energy optimisation during partial loading.
“Providing custom solutions for this type of challenging project is an opportunity to demonstrate the depth of our expertise,” says Alan Bissett, director, Nataol Pump Services who has been providing pump solutions in KwaZulu-Natal for over 40 years.
