RO and NF membrane systems for drinking water production and their maintenance techniques

Elaboration of drinking water supply strategies is closely connected with expansion of private housing, as well as country farms and industries that require water treatment facilities. As a rule, the majority of ground well waters does not meet modern drinking standards due to high content of iron, hardness, strontium, nitrates, fluoride and TDS. Thus, a special respect should be given to small portable and economically reasonable point-of-entry water treatment systems that produce quality water meeting WHO standards. Membrane treatment techniques are based on simultaneous rejection of all types of ionic and molecular water species by semipermeable (RO) polymeric membranes which is more advantageous compared to conventional treatment techniques. The continuous theoretical and experimental research conducted in VODGEO research institute from 1992 to 1999 resulted in development of drinking water production techniques from different natural waters, using Russian-made and foreign polymeric membranes. Computer calculation techniques are developed that enable us to determine optimum characteristics of membrane water treatment systems, such as pressure, recovery, membrane type etc. corresponding to optimum quality water composition (required hardness, fluoride, chloride and TDS content). As a result, water purification techniques were developed providing facilities with operational guidelines to reduce greatly membrane fouling and simplify pretreatment. This demonstrates considerable cost savings and membrane efficiency compared to conventional iron removal and ion exchange softening techniques.