The Oanob treatment plant supplies drinking water to the town of Rehoboth and uses a standard purification process.
As a first step on the plant, chlorine is added to the water from the Oanob Dam for disinfection. This is followed by the addition of lime and flocculant to adjust the corrosivity of the water and invoke the process of flocculation. The addition of these chemicals and the mixing of them with the dam water takes place in the flash mixer.
The water then flows through a flocculation channel where the dirt particles in the water react with the flocculant to form bigger particles called “floc”, which can be removed from the water more easily.
From the flocculation channels, the water is led into two settling tanks, where the floc settles to the bottom. The clearer water on top overflows into concrete channels, leading to the sand filters. The settled floc is removed from the bottom of the tanks periodically.
As the water flows from the concrete channels to the sand filters, chlorine is dosed for disinfection.
Water is further cleaned by filtering through a bed of clean sand. The filtered water then collects in a clear water well underneath the filters. Further disinfection with chlorine gas takes place in this well.
The water is then transferred to the reservoirs for distribution to the Town of Rehoboth.
