Design considerations for a solar-powered desalination system for remote communities in Australia

Water in many areas of Australia is scarce and of poor quality. In some areas high levels of treatment are required either due to contamination of waters or due to high salinity. Nanofiltration (NF) and low pressure RO membranes are well recognised technologies to treat waters of qualities ranging from low salinity surface water to high salinity seawater. In remote communities the operation of such facilities may be limited by the availability of electricity. Solar, or photovoltaic, energy is the ideal source of renewable energy in Australia to overcome this problem. This paper considers the various options for a small system, designed to deliver a permeate flow of 400-1000 litres/day from brackish wells. The most suitable membrane for salt retention and very high organics retention was selected and the pump energy requirements calculated. A submerged ultrafiltration (UF) membrane is used as an alternative to the traditional sand and/or pre-filter cartridges. The removal of natural organics is important where disinfection of the water is required, as chlorination of waters containing natural organics may produce potentially carcinogenic by-products.