Disposal of red mud from aluminum production is a worldwide problem and is of great importance in protecting the environment. In previous studies, the authors determined the possibility of obtaining a composite coagulant for the treatment of natural water and wastewaters. The effectiveness of purification of colored Dnieper water by such a reagent due to the presence of iron and aluminum compounds in its composition was shown. On the other hand, there were difficulties associated with an increase in the content of residual iron in purified water. Obviously, for this reason, iron coagulants (in "pure" form and mixed with aluminum sulfate) have not been used in the purification of Dnieper water. In continuation of these works, we have studied the use of composite coagulants and mixtures obtained from red mud using hydrochloric and sulfuric acids, sulfates of iron and aluminum in different proportions. The article presents the results of seasonal studies on the treatment of Dnieper water using jar tests, simulating the real parameters of the existing water treatment plant. It has been found that the best effect of purifying Dnieper water is achieved by using composite mixtures with a ratio of Fe2O3/Al2O3 not exceeding 1/1. A significant effect of pH on the residual concentrations of iron and aluminum in water has been noted. The results of the work are in good agreement with modern ideas about the coagulation of such waters, explain the failures in the use of iron-containing coagulants, and determine the possible ways of this application in the purification of Dnieper colored water containing a significant amount of natural organic compounds.

Results of test coagulation of highly colored Dnieper water by a composite coagulant (CC) obtained by acidizing red mud are presented. It is shown that CC ensures a decrease of basic quality indexes of Dnieper water by 10–20% more effectively than aluminum sulfate (AS). In this case water is contaminated with iron compounds. To lower its concentration it is proposed additionally treat water with ozone, chlorine dioxide or sodium hypochlorite being fed to mixers or flocculation chambers. An alternative way is the use of composition mixture in the form of addition CC to AS in the ratio 1/2–1/1 (in terms of Fe2O3/Al2O3).

On the basis of research of dispersion composition of pollutants in urban wastewater using laser diffraction methods of their preliminary preparation for further reverse osmotic purification were chosen. It has been found that filtration through a sand filter with the fraction 1.0–2.0 mm followed by microfiltration through ceramic tubular membranes of clay minerals ensures water treatment to standards for input water in reverse osmotic units.

The article gives a simplified model of water deironization on a filtering medium from natural clinoptilolite based on the results of pilot research and industrial tests. Advantages and disadvantages of the model were found. The possibilities of using this model have been shown in optimization of the water demanganization on natural modified clinoptilolite.

We have assessed, by means of the methods of statistics, the compliance of the treatment facilities of the Dnieper waterworks in Kiev with the state-of-the-art in the quality the Dnieper River water and, in the first place, with that of the organic component, which determines its color.