On-Line Zeta Potential Monitoring for Smarter Water Treatment

Zeta potential has been utilized in water treatment to control coagulant charge neutralization for several decades. However, it is less well known that zeta potential also plays a role in optimizing water treatment process performance. Maintaining an ideal zeta potential improves clarification/sedimentation, filtration, and dewatering. However, in many cases, this requires monitoring and control of zeta potential in more than one location. This can be achieved with a single zeta potential optimization system incorporating dual monitoring and control. Advances in electrophoretic light scattering technology, automated and on-line zeta potential analysis capabilities, and automated chemical dosing have brought much needed improvements to water treatment efficiency and performance. For multi-media and polymeric UF membrane filters, maintaining a slightly negative charge is ideal. Ceramic membrane filters can vary from slightly negative to slightly positive. PFAS removal strategies such as GAC and Ion Exchange will benefit from enhanced coagulation by maximizing soluble organic removal and allowing extended carbon and ion exchange run time. Maintaining optimum zeta potential, pre-filtration, can result in a significant increase in conventional filter run time and reduced membrane fouling.

The principle and implementation of zeta potential measurement via continuously monitored phase analysis light scattering (cmPALS) is introduced. The application of zeta potential measurement with respect to jar testing and online monitoring and control are also discussed, and case studies are reviewed.