EWB-JSC has developed a water filtration and purification system called the Bring Your Own Water, or BYOW. Test results have shown that it is capable of decreasing water turbidity to 1 NTU or lower. In this design, incoming water enters the rapid sand filter through a distribution arm at the top of the filter drum and flows down through the sand where small particles and bacteria are removed through a physical straining process. In backwashing mode the system is run in reverse to fluidize the sand bed and allow collected sediment to be washed out of the system.
UV light is used for the final sterilization stage because it can achieve a 99.99% reduction of bacteria, viruses, and protozoa. The disinfection system design, also successfully implemented in communities in Rwanda and Mexico, utilizes a commercial-off-the-shelf disinfection unit and ballast capable of disinfecting water at 6 gpm. All the electronic components will be contained in a weatherproof electrical enclosure along with the necessary electrical and plumbing connections. The system is operated by actuating an electrical timer switch on the side of the box which allows the UV lamp to warm up. This switch turns on the UV system ballast, providing power to the light, and also actuates an electrical solenoid valve to allow the water to flow from the system after 60 seconds have passed. The UV system is powered by a 100 watt photovoltaic panel. The total draw of the disinfection system is approximately 25-40 watts. The PV installation was sized to provide power to the system for about 7 hours per day. Sealed, long life batteries were selected that require no maintenance and will ensure sufficient power is available for up to three days of continuous cloud cover.
L'Esperance Orphanage Implementation
In August 2007, EWB-JSC traveled to the Kibuye region of Rwanda to install a BYOW water treatment system for the L’Esperance Children’s Aid Orphanage. The water treatment system was designed to provide clean drinking water for 100 orphans and supporting staff at the orphanage. The system consists of a roughing filter, rapid sand filter, backwash tank, and UV sanitation box. The system was constructed on a cistern at the orphanage and relies on gravity to create the necessary pressure head for the rapid sand filter. Once water passes through the roughing filter and rapid sand filter, the final stage is through a UV light which sterilizes the input water deactivating any remaining bacteria, viruses, and protozoa. The UV light is powered by a 50 Watt photovoltaic panel. The rapid sand filter is periodically cleaned through the use of a backwashing tank.
Water Treatment Documents