Membrane separation techniques - removal of inorganic and organic admixtures and impurities from water environment - review

Introduction and development of membrane techniques in the production of drinking water and purification of wastewaters, in the last 40 years, was important stage in the field of water treatment effectiveness. Desalination of sea and brackish water by RO is an established way for drinking water production. Significant improvements in design of RO, the application of alternative energy sources, modern pretreatment and new materials have caused the success of the process. NF is the method of water softening, because NF membranes can retain di- and multivalent ions, but to a limited extend monovalent. Drinking water containing viruses, bacteria and protozoa, as well as other microorganisms can be disinfected by means of UF. Viruses are retained by UF membranes, whereas bacteria and protozoa using both UF and MF membranes. For the removal of NOM it is possible to use direct NF or integrated systems combining UF or MF with coagulation, adsorption and oxidation. The use of NF, RO and ED, in the treatment of water containing micropollutants for drinking and industrial purposes, can provide more or less selective removal of the pollutants. The very important are disinfection byproducts, residue of pharmaceuticals and endocrine disrupting compounds. For endocrine disrupting compounds, special attention is paid onto polycyclic aromatic hydrocarbons and surface-active substances, chlorinated pesticides, phthalates, alkylphenols, polychlorinated biphenyls, hormones, synthetic pharmaceuticals and other substances disposed to the environment. The application of MF and UF in the removal of inorganic and organic micropollutants is possible in integrated systems with: coagulation, adsorption, complexion with polymers or surfactants and biological reactions.