Environmental change in the Aral Sea region - New approaches to water treatment

This paper deals with novel approaches to solution of the important freshwater problems facing the Aral Sea Region. These approaches are based on using novel water treatment techniques developed taking into account local climatic and economic conditions. The local problem of removing water hardness and inorganic and organic contaminants can be solved by using proposed fibrous sorbents on the basis of Polyacrylonitrile (PAN). A special oligodynamic method that is particularly effective against typical types of pathogens in the Aral Sea region is proposed to solve a drinking water disinfection technique based on a direct osmosis process, the separation there is driven by natural osmosis, which does not require external pumping energy as in the reverse osmosis process. The specific power consumption of the direct osmosis desalination process is less than 1 k Wh/m(3) for sea water. On the basis of the findings the pilot device with productivity of 1 m(3/)h has been constructed. It consists of solar batteries with the capacity of 500 W for pumping various fluids (feed, brine, product, and working solution) of the desalination device, solar energy heat exchangers for the recovery of working solution, water pretreatment unit on the basis of fibrous sorbents, and a water disinfection device with a very low energy consumption of 0.1 W-h. Due to the financial support of UNESCO in 2005, the device was installed in a village in the Aral Sea Region to remove salts with total concentration of about 17 g/l. Two hundred fifty water disinfection devices have been installed in manual artesian well water pumps through the support of JDA International (Colo., USA). More than twenty water purification systems consisting of filters on the basis of developed fibrous sorbents and water disinfection units were installed in different villages of the Aral Sea Region.