Ecological assessment of water quality of Samotkan river in the area of polymetallic ores mining

The industrial enterprise for the extraction of polymetallic ores Vilnohirskyi Mining and Metallurgical Integrated Works (MMIW) has assumed the responsibility for the removal and sewage treatment of industrial and communal significance. An essential part of the total wastewater discharge enters into the Samotkan river from the largest waste dump called as Skazhena ravine. Sludge setting tank in Skazhena ravine is located on the left bank of the Samotkan river. Kamianske reservoir is a receiving water of debalance wastewater of the plant according to the current permit for special water use, issued for the Vilnohirskyi MMIW. The discharge of waste water from the storage tank into the Skazhena ravine is carried out in the sanitary protection zone of Verkhniodniprovskyi and Aulskyi water intakes. The site of the water object, which is the release of wastewater from the reservoir in the Skazhena ravine is located within the boundaries of the settlement of the city of Verkhniodniprovsk. The tail farm in the Skazhena ravine is a place of waste depository, which are formed at the enriching plant in the process of developing the Malyshevskyi deposit of polymetallic ores. The chemical composition of the Samotkan river is formed under the influence of surface run-off and groundwater run-off, a drainage inflow from the Kamianske reservoir, evaporation of water from swamps, bodies of water, and discharges from the sludge setting tanks (reservoirs) of the Vilnohirskyi MMIW. Comparison of the calculation data of complex pollution with established by means fishery maximum permissible concentrations showed that the water of the Dnipro river at the place of its sampling in the Verkhniodniprovskyi water intake was estimated as “moderately polluted”. But, taking into account the requirements for communal needs, water is characterized as “pure”. The concentration of substances in the return water does not exceed the maximum permissible concentrations in the conditions of communal use of the water object. Changing the channel of the Samotkan river, transformation of several beams into slime tanks, and dumping the quarry waters in Kamianske water storage is a challenge for urgent search of the optimal technologies for solving these problems.