CONTACT CLARIFIERS IN THE PREPARATION OF DRINKING WATER

The article discusses the problem of improving the technological process of clarifying water for drinking purposes using contact clarifiers, which allows to reduce the consumption of reagents, improve water quality, reduce capital and operating costs, and reduce the cost of water. The method of water treatment, based on the use of the phenomenon of contact coagulation, is called the method of contact clarification. This method is able to provide a high and stable effect under various physicochemical conditions of coagulation, changing according to the seasons of the year with lower doses of coagulant than in the usual scheme of water treatment with sedimentation and filtration. It was found that the contact coagulation of suspended and colloidal impurities of water on sand grains when water moves through granular filters is faster, more complete, more stable when the physicochemical conditions of coagulation change according to the seasons of the year. And, finally, at lower doses of coagulant than the usual coagulation of these impurities in the free volume of water in flocculation chambers and settling tanks. It is advisable to use contact clarifier in one-stage treatment schemes for low-turbid colored waters, when the total content of suspended solids in the water supplied to the contact clarifiers, including the suspension that is formed as a result of the introduction of reagents into the water, does not exceed 150 mg/dm3. With a higher suspension content in water, the water consumption for flushing contact clarifiers increases sharply. It was found that the zones of contact coagulation when using a conventional coagulant solution are slightly smaller than when treating water with a modified solution of aluminum sulfate (the latter takes place on the curves of contact coagulation of both low-turbid and turbid waters). The analysis of contact coagulation zones shows that when treating water using a modified coagulant solution, it makes it possible to reduce the calculated doses of coagulant by an average of 30-45% without deteriorating the quality of water clarification.