Application of membrane techniques for the removal of micropollutants from water and wastewater

Abstract

A number of inorganic anions and heavy metals, microorganisms, natural organic matter, and organic micro-pollutants, among them disinfection by-products, pharmaceutical active compounds and endocrine disrupting compounds, 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/L to a few mg/L).

Several common treatment technologies, which are nowadays used for removal of inorganic and organic contaminants from natural water supplies, represent serious exploitation problems. Membrane processes such as RO and NF, UF and MF in integrated systems, Donnan dialysis and electrodialysis as well as MBR and liquid membranes, if properly selected, offer the advantage of producing high quality drinking water as well as purified wastewater which can be drained off to natural water sources.

High-pressure membrane techniques, i.e. RO and NF can be used for direct removal of inorganic and organic micropollutants, while low-pressure (MF and UF) in integrated systems, first of all with coagulation and adsorption and in MBR as well as after complexion with polymers or surfactants.

Processes with ion-exchange membranes are suitable for micropollutants having electrical charge. Because of that property they are used in many large scale applications including the separation of ions, desalination, removal of ionic species etc.