Membrane pretreatment of reverse osmosis: long-term experience on difficult waters

A plate module membrane filtration equipment was operated to evaluate the uranium removal efficiency from drinking water of five different nanofiltration flat sheet membranes. Experiments were carried out using different model waters. Hydrochemical settings were chosen which allow uranium to form those complexes that are the most important for uranium mobilization in natural water: uranyl hydrogen carbonate complexes. Especially the divalent anion complex UO2(CO3)2-2 and the four-valent anion complex UO2(CO3)4-3 which mainly occur in natural water were rejected between 95% and 98% by four membranes and between 90% and 93% by one membrane.