Prediction of optimal coagulant and flocculant dosage for water treatment at surface water intake

Abstract

Reagent treatment is one of the main methods of source water treatment in water supply plants. Suitable values of coagulant and flocculant doses, as a rule, are selected experimentally, and do not vary depending on seasonal changes in indicators. Therefore, to achieve high efficiency of water treatment, there is a need to determine the doses of coagulant and flocculant for the whole year and for separate seasonal periods in order to compare them. Regression analysis allowed us to quantitatively describe the relationships between turbidity, color, oxidizability and hardness of the source water and reagent doses. At the same time the significance of the influence of the listed indicators on the value of coagulant and flocculant doses was determined. The multifactorial relationship between the water quality indicators at the water source (turbidity, color, oxidizability and general hardness) and the parameters of water treatment processes (dosage of coagulant and flocculant) was studied for both the annual cycle and for specific shorter time periods. Calculation of coagulant and flocculant doses for the entire annual period of the water source in practice, makes it possible to predict suitable doses of reagents before trial coagulation. The equations obtained for individual periods take into account the influence of individual factors, and, therefore, will allow to increase the efficiency of water treatment process control, reduce the consumption of reagents and significantly increase the barrier role of water treatment facilities.