Exploration of ferrate(VI) potential in treating Lake Constance water

Occurrence of micropollutants in water and their potential impact on the environment and human health are arising concerns. The micropollutants are not removed efficiently by current wastewater treatment and a small amount of them get released into receiving waters accompanying the discharging of the treated wastewater effluents. Therefore, it is useful to investigate an advanced or alternative technology to remove traces of micropollutants in Lake Constance water during drinking water treatment. Among various oxidation processes, ferrate(VI) has received extensive attentions due to its superior dual properties of oxidation and coagulation. The work in this communication is the first trial using ferrate(VI) in comparison with FeCl3/ozonation to treat lake water and to remove micropollutants in the region. The results of pilot-scale trials showed that 10% of metformin, benzotriazole and acesulfam can be removed by ferrate(VI) at a dose of 0.1 mg L−1 from raw water, but FeCl3 with or without pre-ozonation cannot achieve the same performance. The degradability of three additional micropollutants by ferrate(VI) oxidation followed the sequences of bisphenol-S (BS) > azithromycin (AZM) > imidacloprid (IMP) was evaluated, and 100% concentration reduction of BS was achieved. The work suggests that ferrate(VI) is a potential alternative to the existing treatment processes for drinking water treatment.