Operations and Maintenance in Windhoek. Namibia is the most arid country in Sub-Saharan Africa and its capital faces serious water challenges. The average rainfall is 360 mm, with an annual evaporation of 3,400 mm.

The only perennial rivers are on the country’s northern and southern borders, 750 and 900 kilometres from the capital, Windhoek, respectively. Since all naturally available water sources in and around Windhoek were already being fully exploited, plans were drawn up to build the New Goreangab Water Reclamation Plant. Construction of the plant, which is based on the latest available proven water treatment technology, was completed in 2002. The New Goreangab Water Reclamation Plant (NGWRP), owned by the city of Windhoek, produces 21 megalitres of potable water per day. The plant’s operation and maintenance have been outsourced through a Private Management Agreement with the Namibian Windhoek Goreangab Operating Company (WINGOC).

System Design
WINGOC recycles wastewater to produce drinking water. This involves both mechanical and biological steps as well as ozonation and membranes. The NGWRP system uses the following treatment processes:

• Raw water blending and powder
  activated carbon addition
• Pre-ozonation and coagulation
• Flocculation and dissolved air fl otation
• Rapid gravity dual media fi ltration
• Ozonation
• Biological activated carbon filtration
• Granular activated carbon adsorption
• Membrane ultrafiltration

Analytic
In addition to the implementation of advanced technology for the New Goreangab Water Reclamation Plant, the plant’s analytical control regime makes up part of the reclamation policy. Organic and microbiological parameters are used, in addition to the chemical/physical parameters, and toxicological analyses of the water are performed on a regular base. A side stream of the reclaimed water is continually fed through a biomonitoring system. This system allows harmful substances in the water to be detected before the water reaches the public.