The treatment starts at the abstraction point of raw water at the Von Bach Dam. At this point if raw-water conditions require, powdered activated carbon is added to minimise unpleasant tastes and smells.
As the water arrives at the treatment works, the water is chlorinated before it enters the plug flow reactor, where the water is dosed with lime to reduce the corrosivity of the water. In the plug flow section the water is also aerated to remove volatile compounds which also give rise to unpleasant odours.
After that the water enters the flash mixer where potassium permanganate and a flocculant are mixed into the water. Potassium permanganate is added to aid in removing manganese and iron. The flocculant binds the small clay particles into larger particles called “floc” which can be removed more easily.
From the flash mixer the water is distributed to flocculation channels and chambers where the flocculant is given time to react with the water. Once the floc has formed, the water enters the 8 settling tanks in which the floc settles to the bottom and is withdrawn as a slurry.
After the settlers, chlorine is again added before the water enters the sand filters to further remove any unsettled floc.
The water is then stored in 3 clear water wells from where it is pumped towards Windhoek and Okahandja. Chlorine is added for further disinfection and caustic soda to reduce the corrosiveness of the product water.
Further disinfection takes place at one of the pump stations on the way to and at the terminal reservoir in Windhoek .
