N2 - In this paper we studied the intensification of the water clarification process on contact clarifiers with quartz sand fil-tering bed, which was modified with a solution of aluminum sulphate coagulant. The modification of the quartz sand filter-ing 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 de-crease and it the adhesion of particles becomes possible. This is the process of coagulation of the colloid. The forces of mu-tual gravity between the colloidal particles begin to predominate over the electric repulsive forces at the ζ-potential of thesystem 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%. L1 - http://journals.pan.pl/Content/112863/PDF/Dushkin%20Martynov%20429.pdf L2 - http://journals.pan.pl/Content/112863 PY - 2019 IS - No 41 EP - 60 KW - aluminum sulphate KW - contact clarifier KW - filtering bed KW - intensification of purification KW - quartz sand KW - surface water purification KW - water filtration A1 - Dushkin, Stanislav S. A1 - Martynov, Serhii PB - Polish Academy of Sciences; Institute of Technology and Life Sciences - National Research Institute DA - 2019 T1 - Intensification of the work of contact clarifiers during the drinking water preparation SP - 55 UR - http://journals.pan.pl/dlibra/publication/edition/112863 T2 - Journal of Water and Land Development