Namibian Sea Water Desalination plant under construction

Sunday 1st August, 2010

Aveng Water was awarded a Contract to build sea water desalination in Namibia, the largest in the Southern Africa. Construction of the plant is underway with plant commissioning expected later in 2009. UraMin, now a part of AREVA are the owners of this 54,000 m3/day desalination plant.

The plant, situated 30km north of Swakopmund, will pump treated water 54km overland to Trekkopjie's Uranium mining operation.

The infrastructure includes a multi-million rand sub-sea pipeline drawing in sea water 1000m beyond the surf zone. Extraction of sea water beyond the high energy surf zone ensures a raw sea water quality low in suspended solids, minimizing the cost of land based pretreatment processes. The intake and brine pipelines were designed by WSP Africa Coastal Engineers based in Stellenbosch while M & R Marine was appointed to construct the 1000m intake pipeline.

Ensuring a stable supply of clean sea water along one of the most biologically active coastlines in the world, has presented many unique challenges. The prevailing weather and environmental conditions have further necessitated careful review of all aspects of the design and construction activities.

After screening and pretreatment by Ultrafiltration, filtered sea water is processes through reverse osmosis membranes. Reject salt water is returned to the sea through a separate pipeline which runs parallel to the intake pipelines. Specially designed diffusers are used to dilute the brine stream back into the sea water.

After an extensive review of the progress made in using UF as pretreatment for SWRO plants internationally, Keyplan selected Norit X-Flow SEAGUARD UF membranes. Based on techno - economic selection criteria, TORAY was awarded the contract to supply the TM 820-400 SWRO membranes.

Energy Recover, Inc (ERI) a global leader of ultra high energy recovery products and technology for reverse osmosis has been selected to ensure maximum power recovery from the brine discharge.