Zeta Potential and Optimizing Coagulation in the Water Treatment Process

Surface water treatment, water remediation and waste water treatment are critical issues in providing safe drinking water. Control of turbidity and removal of NOM remains one of the main challenges facing water utilities. Control of the flocculation process and adjustment of coagulant dose during the course of water and waste water treatment is often a challenging step in the water treatment process.

Zeta potential is a measure of the electrical potential between particles, and indicates the repulsive interaction between particles; a zero zeta potential means that the conditions for aggregation of contaminants are maximized. Monitoring zeta potential during the water treatment process allows for accurate and precise assessment of the charge neutralization process. Zeta potential provides a measurable value to monitor the optimal coagulant dose during the water clarification process. 

The benefits of using zeta potential measurement to determine water treatment-control strategies have been documented through case studies and will be reviewed. Results from both laboratory analyzers (Zetasizer Nano Z) and the on-line, automatic system (Zetasizer WT) will be discussed. Based on plant processing requirements, on-line real time monitoring is often preferred so that small changes in zeta potential can be immediately identified for water treatment optimization. On-line continuous process zeta potential monitoring benefits will be illustrated, by reporting on the experiences of utilities such as Tacoma Water in WA, Aurora Water in Aurora Colorado as well as other water treatment facilities in the US and UK.