Ecological Efficiency of Surface Water Purification by the Method of Structuring Contaminated by the Activities of the Agroindustrial Complex

Abstract

Biochemical oxygen consumption for five days in water without structuring is 5.0 mgO2/dm3, which is 1.7 MPC. With the structuring of water, the indicator of biochemical oxygen consumption decreased by 20%, to 4.0 mgO2/dm3, which was 1.3 MPC. The pH of water without structuring was 7.27, and in structured water it decreased by 0.7% or by 0.5 pH to 7.22 pH. The concentration of suspended solids in unstructured water was 180.0 mg/dm3, while the maximum permissible concentration (MPC) of suspended solids in surface waters was 15 mg/dm3. This indicates a strong pollution of the reservoir with suspended substances, 12 times higher than the permissible limits. With the structuring of water, the concentration of suspended solids decreased by 50.6%, to 89.0 mg/dm3, but this was 5.9 times higher than the MPC. The actual concentration of chlorides in water without structuring was 108.92 mg/dm3, and with structuring of water, the concentration of chlorides increased by 14.7%, to a level of 127.64 mg/dm3. In comparison with the maximum permissible concentration of chlorides in the reservoir, in both cases the actual chloride content was significantly less than the MPC and amounted to 0.3 and 0.4 MPC, respectively. The content of ammonium nitrogen in the reservoir without structuring was 6.63 mg/dm3, which was 4.4 times higher than the permissible limits. The structuring of water contributed to a decrease in the concentration of ammonium nitrogen in surface waters by 16%, to 5.57 mg/dm3. This concentration of ammoniacal nitrogen in water also exceeded the maximum permissible value by 3.7 times. The nitrate content in water without structuring was 5.18 mg/dm3. The structuring of water contributed to a decrease in the concentration of nitrates by 24.7%, to a level of 3.9 mg/dm3. This concentration of nitrates in the reservoir is significantly lower than the permissible limits and amounts to 0.52 and 0.39 MPC, respectively. The actual concentration of surfactants in the reservoir without structuring was 0.01 mg/dm3. After structuring, the concentration of surfactants in water was less than 0.01 mg/dm3, which is less than the technical sensitivity of the measuring device. Therefore, the ecological efficiency of structuring water to reduce the concentration of synthetic surfactants is more than 10%. Since the maximum permissible concentration of synthetic surfactants in water bodies is 0.2 mg/dm3, their actual concentration was much less than this indicator. Permanganate oxidizability of water without its structuring was 10.67 mgO2/dm3. With the structuring of water, permanganate oxidation decreased by 27.6% and amounted to 7.73 mgO2/dm3. Without structuring water, the permanganate oxidizability was 1.1 MPC, which was more than the permissible level, and when using a structurant, it was 0.8 MPC, which ensures acceptable limits. The transparency of the water without structuring was 2.5 cm. The structuring of the water led to an increase in the transparency of the reservoir by 44.4%, up to 4.5 cm. The minimum permissible transparency of surface waters should be 10 cm. This indicates that the water from both experimental variants is very contaminated with an excess of the permissible limits by 4 and 2.2 times, respectively.