Solar powered direct osmosis desalination

The paper deals with a novel solar powered water desalination technique based on direct osmosis process. The separation is driven by natural osmosis, which does not require external pumping energy as in the reverse osmosis process. Therefore, the specific power consumption of the desalination process is reduced from approximately 5 kWh/m3 for seawater reverse osmosis to a value of less than 1 kWh/m3. The pilot device with productivity of 1 m3/hr has been constructed. It consists of solar batteries with capacity of 500 W for pumping various fluids (feed, brine, product, working solution) of the desalination device, solar thermal exchangers for recovery of working solution, water pretreatment unit on the base of fibroid sorbents and water disinfection device with energy consumption of 0.1 Wh. With the support of UNESCO in 2005 the device was installed in a village of Aral Sea Region to remove salts with total concentration of about 17 g/l. The product salinity after the treatment was about 50 mg/l.