Petroleum group Shell’s Three Sisters Ultra City, on the N1 Highway, near Beaufort West, has installed a 150 m3/d effluent treatment and grey-water recycling plant, which has resulted in the recovery of 25 000 ℓ of water a day out of season and 120 000 ℓ of water a day in season.
This water-saving scheme was undertaken by Shell; physical asset management company Pragma undertook the maintenance of the Shell network and green water solutions company Cool Technology was responsible for the project’s on-site work.
Pragma projects coordinator Willie Brynard tells Engineering News that the system has also been installed at the Mvoti and Estcourt Ultra City outlets, in KwaZulu-Natal, and will soon be installed at two Ultra City outlets in Limpopo, including the Pietersburg Ultra City outlets.
He notes that the plant installation involves minimal disruption, owing to its cost-effective design.
“We agreed that water needed to be saved at this site, as constantly drilling boreholes was not the solution. The cost was escalating and water consumption was increasing. It was agreed that a solution should be found to recycle and polish the final effluent for reuse in the toilets.”
Brynard adds that the rest of the recovered water will be used to irrigate the site, as the water conforms to the legislative discharge and irrigation standards. Irrigation will also require sufficient storage for the treated water at the site.
The effluent treatment plant has a modular membrane and produces grey water to standards that are below the required discharge standards.
The plant uses flat-sheet membrane technology to adhere to the most stringent discharge guidelines and allows for the reuse of recovered toilet wastewater using cationic resin filters and sterilisation.
The plant is also much smaller, as no clarifier is required in a membrane bioreactor plant such as this one, making it possible to double the capacity on the same footprint. It also has a programmable logic controller that reduces the chances of settings tampering.
“Preliminary results show a drastic reduction in water consumption. As one of the busier Ultra City sites, it uses up to 120 m3/d of water in season, while the average daily consumption is between 20 m3 and 55 m3. The plant’s on-site water recovery is between 60% and 70%.
“This is a recovery and reuse of more than 10- million litres of water a year. Metering using online monitoring is being installed to capture exact data for future analysis and reporting purposes. The membranes ensure that water is 100% sterile with a coliform count of zero,” says Brynard.
Pragma operations manager Andre Cloete says the company focuses on improvement and on ensuring that it assists clients in maintaining and preserving their assets.