Successful Removal of Algae through the Control of Zeta Potential

Abstract

Algae can interfere with treatment processes at a water treatment works. Coagulation control is critical to reduce the impact of algae on downstream processes. This paper investigates the coagulation and flotation of four species of algae – Asterionella formosa, Melosira sp., Microcystis aeruginosa, and Chlorella vulgaris. The zeta potential at optimum removal was measured and it was observed that when the zeta potential was reduced to between −8 mV and +2 mV, removal of algae and associated organic material was optimized, irrespective of the coagulant dose or pH. Process control using zeta potential is therefore a viable tool for algae removal.

Keywords:

• Algae
• coagulation
• dissolved air flotation (DAF)
• zeta potential

Acknowledgments

The authors would like to thank the Engineering and Physical Sciences Research Council (EPSRC), Yorkshire Water, Thames Water, Northumbrian Water and Anglian Water for their financial support.