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

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.