ABSTRACT
Windhoek, the capital of Namibia, is situated in the central highlands of Namibia, approximately 1,600 metres above sea level. The nearest perennial river is approximately 700 km away. The average annual rainfall is approximately 360 mm, whilst the evaporation is approximately 10 times higher. The integrated approach towards water reuse in the city entails water reclamation for potable use, provision of irrigation water for landscaping through a dual pipe system and artificial recharge of the Windhoek Aquifer (water banking) with high-quality treated water sourced from surface sources blended with reclaimed water. In 1968, a direct reclamation system from treated domestic sewage to augment the potable water supply to the city was pioneered. The process was improved over time and the Goreangab Water Reclamation Plant has consistently supplied water of acceptable quality over the years. Due to water scarcity in the region and with few alternative supply sources, the construction of a new water reclamation plant became necessary. This plant incorporated a modified process train, based on the multiple barrier concept to provide high-quality water in accordance with agreed standards. The new plant, with a capacity of 21 000 m3/day, was completed in August 2002, and is capable of providing approximately one-third of the city’s water demand until 2012. All the design parameters of the old plant were re-assessed and evaluated in the design of the new plant. The reclamation of water over a period of 37 years has demonstrated that, with proper care and diligence, water of acceptable quality can consistently be produced from mainly domestic effluent. The cost of reclaimed water versus other supply options to Windhoek is very competitive. Although perceived to be very controversial in the rest of the world, the consumers in Windhoek have accepted that reclaimed water forms part of the potable water supply.
