The problem of pollution of drinking water with nitrate ions and modern methods of its solution

The article discusses various regulatory documents that regulate the content of nitrate ions in drinking water, as well as the impact of nitrates on human health and safety. The results of studies on nitrate ion contamination of sources of drinking water supply in 5 regions of Ukraine are presented. Physico-chemical analysis was carried out for water sources from wells in rural areas, city limits and in the territories adjacent to cities. The relevance of the problem of water pollution with nitrate ions, which requires the search, implementation and improvement of water purification methods from nitrates, has been proven. A comparative analysis of the advantages, disadvantages and features of the use of various methods of removing nitrate ions from drinking water, including water from non-centralized sources of water supply, was carried out. Biological, ion-exchange, adsorption, electrochemical methods, as well as baromembrane methods, in particular the reverse osmosis method, are used to purify water from nitrate ions. The regularities of the reverse osmosis process during the removal of nitrate ions from model solutions and water from wells were studied. Reverse osmosis membranes manufactured in the USA by Filmtec type TW30-1812-50 were used for experimental studies. Model solutions of Mg(NO3)2, Zn(NO3)2 and, directly, water from non-centralized sources of water supply were used as the tested water. Membrane selectivity and permeate selection coefficient were determined according to the known method. Parametric curves of the dependence of the selectivity of the membrane in relation to NO3- on the increase of the working pressure from 0.5 MPa to 1.9 MPa for model solutions of different concentrations were constructed. The dependences of the change in the concentration of nitrate ions in well water and the selectivity (φ, %) of the membrane in relation to NO3- on the working pressure were obtained. On the basis of the research results, a conclusion was made about the high efficiency of water purification from nitrates by low-pressure reverse osmosis (in the range from 0.5 MPa to 1.9 MPa) and the parameters of the researched process were determined, which would allow reaching the MPC standards for nitrates in drinking water.