The dissertation is a completed scientific study in which an actual scientific and applied task is solved regarding the study and improvement of the technological process of drinking water production from a surface water source in the case of its treatment with chlorine dioxide and ferric chloride in the conditions of martial law and emergency situations of a different nature.
In the dissertation, it is stated that the composition of the river water at the place of drinking water intake of the Dnipro water station of the city of Kyiv according to priority chemical indicators during 2022-2023 gradually deteriorated. This, along with changes in drinking water quality requirements during the martial law period, affected the technological process of drinking water production. The smaller ratio of the dose of ferrous chloride to the dose of chlorine dioxide is a factor in the formation of more chlorites in drinking water, which are the priority byproducts of chlorine dioxide disinfection. It was established that after treatment of drinking water to the mixer with chlorine dioxide and ferric chloride already at the outlet of the mixer, there is a significant decrease in the concentration of chlorine dioxide (by 60-65%) and its gradual decrease in the water after the subsequent water treatment facilities - settling tanks and filters (more by 10-20%). At the same time, the maximum concentration of chlorites in drinking water is detected at the entrance to the mixer (they are formed in the amount of 40-60% of the initial dose of chlorine dioxide), and then it decreases due to the presence of water in the mixer (by 15-90%), a settling tank and a quick sand filter (by 20-60%). After the secondary treatment with chlorine dioxide (carried out after the filters and before the RCV), its concentration in the water increases slightly, and then gradually decreases in the water supply (the annual average concentration in the water supply is 0.16±0 mg/l). During the transportation of drinking water through a 2 km long water pipeline and distribution network, the chlorine dioxide content is reduced by 2 times, and the concentration of chlorites does not change.
Linear dependences of the content of chlorites in the water at the inlet of the mixer and the primary dose of chlorine dioxide, changes of chlorites in the water between the outlet and the inlet of the mixer on the dose of iron chloride, the concentration of chlorites in the water of the distribution network on its concentration in the water at the outlet of the mixer were established. The results of the correlation analysis established a connection between the concentration of chlorites in consumers' drinking water and the contamination of river water at the point of water intake by microorganisms and organic substances. It was established that there are annual fluctuations in the quality of drinking water in the distribution network according to microbiological indicators, which requires the use of an additional method of minimizing them for about two months in the warm period of the year.
In general, the use of chlorine dioxide and ferric chloride instead of chlorination with preammonization at the water supply station made it possible to: reduce the number of reagents used from 5 to 4; abandon the use of three toxic gases (ozone, chlorine and ammonia); reduce the content of residual aluminum in drinking water; to significantly increase the efficiency of water purification from organic substances, in particular, on average, in terms of chemical oxygen consumption - more than 2 times.
Mathematical models have been developed that make it possible to manage the technological process of surface water treatment in order to obtain the desired characteristics of drinking water quality according to priority indicators. If the actual parameters of the technological process are compared with the data of the models, it is possible to determine the degree of contamination of drinking water with chlorites at individual stages of its processing and transportation.
Using our improved Czech risk assessment methodology, which is a tool for managing the risks of the drinking water supply system, it was found that out of the 3 reagent treatment options, only the third (double treatment with chlorine dioxide, ferric chloride, aluminum sulfate, and chlorine) contributes the greatest reduction in the risk of drinking water hazards.
Optimizing the drinking water production process should be based on improving approaches to its production control. The principles of production control of the quality of drinking water were developed for the first time in the conditions of military aggression of the Russian Federation against Ukraine. The proposed method of drinking water quality control will lead to a reduction in laboratory research costs.
