Possibilities of the dead-end ultrafiltration in hard water treatment Original Research Article

Comparative investigations of premodified and unmodified membranes were conducted in the process of deadend ultrafiltration of solutions featuring high calcium hardness. It was shown that application of membranes subjected to preliminary modification by filtering under pressure of Na-CMC aqueous solution to treat waters having the initial CaSO4 hardness of 56 mg-eq/1 in the absence of a scaling inhibitor facilitates the reduced formation of CaSO4 scale on membranes, while the introduction of an inhibitor to the solution subjected to filtering enables us to reduce the inhibitor effective concentration by a factor of 4 and increase the time of scale free service of membranes by a factor of 1.5. In this case the complete recovery of volume flux of membranes can be achieved by simple flushing with water.