Abstract
A number of inorganic anions and metals, especially heavy metals, at certain conditions, have been found in potentially harmful concentrations in numerous water sources. The maximum permissible levels of these compounds, in drinking water and wastewaters discharged to environment, set by the WHO and a number of countries are very low (from μg/dm3 to a few mg/dm3). Several common treatment technologies, which are nowadays used for removal of inorganic contaminants from natural water supplies, represent serious exploitation problems. Membrane processes such as reverse osmosis and nanofiltration, ultrafiltration and microfiltration in integrated systems, Donnan dialysis and electrodialysis as well as membrane bioreactors, if properly selected, offer the advantage of producing high quality drinking water without inorganic substances as well as purified wastewater which can be drained off to natural water sources