The Goreangab Water Reclamation Plant, in the Republic of Namibia, is one of the most sophisticated water reclamation plant in the world. It provides drinking water from wastewater.
Description of the Process
Windhoek, situated in the center of Namibia, one of the most arid countries in Africa, with perennial rivers in excess of 500 km to the North or South, mainly depends on water supply from boreholes and three surface dams in ephemeral rivers some 60 to 200 km away. Water shortages from these supplies prompted the city to look for alternatives to augment the water supply. The first reclamation plant started to operate in 1968 with a capacity of 4,800 m3/d. Since then the reclamation process has undergone various changes of improvement. In September 2002 the New Goreangab Reclamation Plant (NGRP) was commissioned having a 21,000 m3/day capacity. The plant has leading-edge technology, which will provide multiple barriers against pathogens including ozonation, membrane ultra filtration and residual chlorination. The old plant is now treating effluents for irrigation of parks and sports fields.
High population growth rates over the past 100 years continued to increase the water demand. Supply authorities had to develop new resources as existing sources were depleted. Repeated periods of erratic rainfall ensured that direct reclamation continued to play an important role to augment the Windhoek water supply. Direct reclamation became a reality in 1968 when severe water shortages were experienced before the extension of the state water supply scheme could be completed. The first reclamation plant started to operate in 1968 with a capacity of 4,800 m3/d. Since then the reclamation process has undergone various changes of improvement. Investigations conducted during 1991 recommended that with minor changes to the plant, the capacity could be extended and the final water quality improved. During a drought in 1992, where state supplies could not deliver the required quantity, the then existing plant was upgraded and extended to an interim capacity of 14,000 m3/d with the intention of ultimately reclaiming 21,000 m3/d. During another severe drought in 1997 it was however decided to build a new reclamation plant at an adjacent site to the Old Goreangab Reclamation Plant. During the period 1992 to 1998, all the components of the reclamation system were reviewed and re-analyzed and incorporated into the design of a new reclamation plant. In September 2002 the New Goreangab Reclamation Plant (NGRP) was commissioned. The old plant is now treating effluents for irrigation of parks and sports fields.
Factors that contributed to the success of the project
The most important project benefits are: good drinking water for the residents, no discharge of wastewater, fewer groundwater extractions. No outbreaks of any disease have been reported or related to this treatment facility.
Advice for future developments to futher develop the trend
The practical experience at Windhoek demonstrates that a direct wastewater reclamation system can be a practical, responsible way of augmenting potable water supplies in arid regions, but it requires comprehensive planning, training and on-going commitment for its continued success.