Capabilities of Ultra- and Nanofiltration in the Purification of Dnieper Water from Natural Organic Compounds

It has been shown that the ultrafiltration treatment of Dnieper water with the use of PA-20, PAN-20, and UPM-20 membranes does not provide the necessary level of total organic carbon for centralized water supply (<= 8 (mg C)/dm(3)) in all the cases. However, the best result is obtained on the UPM-20 membrane. The application of an OPMN-P nanofiltration membrane results in that the total organic carbon decreases even below the established normative value, i.e., to 1.1-1.7 (mg C)/dm(3), and the specific capacity of the selected membrane further sustains no changes up to the permeate takeoff degree of 90% after decrease for the first 10 min of operation in contrast to the ultrafiltration membranes. When processing the experimental data in compliance with the convective filtration theory, it has been established that the ultrafiltration UMP-20 membrane first (similar to 40 min) results in the clogging of its pores with the further transition through an intermediate mechanism to filtration with the formation of a precipitate on its surface. The nanofiltration membrane is characterized by the immediate formation of a precipitate on its surface, being the most advantageous variant from the economic viewpoint. The remineralization of the formed nanofiltration permeate by means of dolomite grains provides the production of water, which is full in calcium and magnesium ions from the physiological viewpoint. The results from the biotests of water samples at the level of a fish organism has shown the absence of any acute and chronic toxicity and, however, the input Dnieper water was revealed to have a genotoxic effect on the blood samples of selected test objects. Chronic water toxicity has been revealed at the level of a hydra and daphnia organisms. The biological testing of the remineralized nanofiltration permeate has shown that it meets the biological parameters of potable water supply.