“Each nomination saves RaHa money that would otherwise be spent on field officers and publicity. Your nomination frees that money to be spent directly on clean water for the community or the school.”
– Titi Kadu, RaHa Founder
Earth Dams (silanga)
We intend to install specialist rainwater filter in the dam wall – these are filters for non-rooftop rainwater. The filter function is an up-flow process and this allows for a design with little height difference between inlet and outlet. The cleaned water has an excellent water quality. The rainwater is cleaned by basic operation of the following processes:
Incoming rainwater is led down to the basal section of the filter shaft. A hydrodynamic separator built in the base section promotes particulate sedimentation.
The water is led into this separator tangentially and generates a radial flow pattern. Particles settle into the silt trap located below the separation chamber. As there is no current there is little remobilisation (washout) of the retained sediment.
Above the separation chamber is the filter element, occupying the full shaft width and so all water must flow up through it. The Siltation of this filter is slowed due to the upwards flow, and the fact that the filter is below the water level.
The filter is easily exchanged. The complete single filter element is removed using the handle inside the overflow pipe. Under normal conditions the filter will last for 2 years, maintenance free.