Coagulation monitoring in surface water treatment facilities

Abstract

Coagulant dosing is traditionally determined according to results from jar-tests or operator's experience, which often lead to overdosing or insufficient dosing. In this study, the feasibility of applying an optical monitoring technique to determine chemical dosage and to monitor the coagulation performance in water treatment plants were assessed. To examine the applicability of the monitor under various operation conditions, series of batch trials in the field were conducted to explore the effects of turbidity, pH and rapid mixing intensity on the effectiveness of coagulation. The performance was directly reflected in the output ratio of the monitor, which proved to be an effective index for the floe size and its settling velocity. Therefore, we consider that the optical monitor is an useful instrument in monitoring coagulation in water treatment.