For 50 years, Windhoek, the capital of Namibia, has been producing drinking water from its wastewater
| The challenge
- Namibia is one of the most arid countries in Africa: the average rainfall is 250 mm per year, but the heat causes 83% to evaporate - only 1% of rainwater infiltrates into the ground
- Consequently, the water supply of Windhoek - located in central Namibia - depends mainly on boreholes and three dams located 60 and 200 km away
- The City therefore had to seek alternative water supply for the approx. 400 000 inhabitants
| Veolia’s solution
Successful direct reclamation as practiced in Windhoek is based on the practice of diverting industrial and other potentially toxic waste water from the main domestic waste water stream. The domestic waste water is treated to produce an effluent of adequate and consistent quality which is further treated to produce safe potable water. In addition, it is important to continuously maintain a multiple-barrier treatment sequence as a safeguard against pathogens and other potentially harmful and unwanted contaminants.
Intensive bio-monitoring programmes and other tests are carried out on reclaimed water, and no negative health effects have been detected as a result of the use of reclaimed water since 1968.
In order to ensure successful direct reclamation, the multiple-barrier approach ensures that at least two (in many cases three and more) effective removal processes are in place for each crucial contaminant that could be harmful to human health or aesthetically objectionable.
A ten-step process guarantees sustainable drinking-water supply:
| The benefits
Recycling wastewater increases the amount of drinking water available, but it also has a twofold benefit for the environment: it avoids tapping into natural resources and significantly reduces pollutant discharges.