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Intensification of the contact clarifiers work during the drinking water preparation

Dushkin, Stanislav S., Martynov, Serhii, Dushkin, Stanislav S.
Journal of water and land development 2019 v.41 no.1 pp. 55-60
adhesion, aluminum sulfate, coagulants, coagulation, colloids, drinking water, filtration, gravity, quartz, sand, surface water, total suspended solids, water treatment, zeta potential
In this paper we studied the intensification of the water clarification process on contact clarifiers with quartz sand filtering bed, which was modified with a solution of aluminum sulphate coagulant. The modification of the quartz sand filtering bed was carried out by applying to the surface of grains of quartz sand solution of coagulant aluminum sulphate with different doses. Investigation of the electrokinetic potential of the filtering material (quartz sand) was carried out by the percolation potential method. The influence of electrical properties (size and sign of the charge) of the filtering bed itself and suspended solids in the water on the filtration process was studied. The filter material – quartz sand used in contact clarifiers has a negative electric charge. When the electric charge of the particles decreases, that is, as the ζ-potential decreases, the repulsive forces decrease and it the adhesion of particles becomes possible. This is the process of coagulation of the colloid. The forces of mutual gravity between the colloidal particles begin to predominate over the electric repulsive forces at the ζ-potential of the system less than 0.03 V. Modification of quarts filtering bed with a solution of coagulant aluminum sulphate recommended for the purification of surface water allows: to intensify the process of water clarification, to reduce the consumption of reagents by 25–30%, with the obtaining purified water of the required quality, to reduce the production areas necessary for reagent management of treatment facilities, and to reduce the cost of water treatment by 20–25%.