Drinking water treatment by ferrate(VI) and toxicity assessment of the treated water

Abstract

The work presented in this paper identified whether ferrate(VI) can be used as an alternative to the existing FeCl₃ in drinking water treatment plant at Lake Constance Water Supply of Germany. The performance of ferrate(VI) was tested in a pilot plant, which includes micro-screening, pre-ozonation, coagulation, and rapid filtration processes. With a ferrate(VI) dose of 0.1 mg/L and without pH neutralization, the average particle removal percentage (in terms of particle counting) after filtration was 93% for raw water and 97% for ozonized water, which is satisfied to the treated water quality demand for particle removal. In comparison with using ozonation and FeCl₃ coagulation, ferrate(VI) can remove 10% metformin, benzotiozole, and acesulfam from raw water but FeCl₃ with ozonation cannot. Moreover, ferrate(VI) treated water did not generate bromate but ozonated water did (~11 μg/L). Finally, ferrate(VI) can effectively replace both ferric chloride and hydrogen peroxide in terms of achieving the required treatment performance and minimizing residual ozone, and no interaction between genotoxic effects and ferrate(VI) treatment was observed. This adds promising benefit of using ferrate(VI) for the given water quality and operating conditions in drinking water treatment.

Keywords:

• Coagulation
• Drinking water treatment
• Ferrate(VI)
• Genotoxicity test
• Micro-pollutant reduction
• Ozonation
• Particle removal

Acknowledgments

We thank Glasgow Caledonian University, Zweckverband Bodensee-Wasserversorgung, and Zweckverband Landeswasserversorgung Water Board of Germany for offering research studentship to H.B.P. Durai. We are also grateful to the staff at the pilot plant and laboratory at Zweckverband BWV. The views of this paper may not necessarily represent those of the two water companies.

Notes

Presented at CEST2015—14th International Conference on Environmental Science and Technology, Rhodes, Greece, 3–5 September 2015