Treatment of liquid radioactive waste by membranes techniques - Needs and future trends

The nuclear industry generates a broad spectrum of low and intermediate level liquid radioactive wastes (LRWs). The treatment methods used for liquid radioactive waste are related to the conventional processes used for the treatment of the industrial wastewater, like chemical treatment, adsorption, filtration and ionic exchange. The use of such of techniques is limited due to their decreased capacity to remove the radioactive contaminants, the increased operational costs (e.g. evaporation) or the yielding potential for significant quantities of secondary solid waste. After development of suitable membrane materials and their long-term verification in conventional water purification fields, the membrane processes have been adopted by the nuclear industry as a viable alternative for the treatment of LRWs. The most utilized processes in the field of water and wastewater treatment are those utilizing pressure gradient as the process driving force. These processes include reverse osmosis, nanofiltration, ultrafiltration and microfiltration, allowing the selective removing both dissolved and particulate contaminants. (authors)