Coagulant control in water treatment

Abstract

Optimization of coagulant dosage in water treatment is becoming more critical as a result of increased attention to removal of micropollutants, THM precursors, and pathogens resistant to disinfection. At the same time, the availability of a large number of coagulants, flocculants, and other additives, and the recent introduction of technologies for the continuous characterization of coagulated flows, has increased the ability to optimize coagulation while increasing the complexity of this optimization process. This article reviews traditional methods for the control of coagulant selection and dosing, summarizing advantages and disadvantages of various techniques. The two aspects of coagulant control which have recently provided improved coagulation capabilities — improved coagulant products and new particle characterization technologies — are reviewed in depth. The article thus provides a comprehensive update on both coagulant control theory and current application.

Key words:

• coagulation
• flocculation
• water treatment
• coagulant
• flocculant
• polyelectrolytes
• electrokinetics