Progress in the development and use of ferrate(VI) salt as an oxidant and coagulant for water and wastewater treatment

This paper reviews the progress in preparing and using ferrate(VI) salt as an oxidant and coagulant for water and wastewater treatment. The literature revealed that due to its unique properties (viz. strong oxidizing potential and simultaneous generation of ferric coagulating species), ferrate(VI) salt can disinfect microorganisms, partially degrade and/or oxidise the organic and inorganic impurities, and remove suspended/colloidal particulate materials in a single dosing and mixing unit process. However, these findings have not yet lead to the full-scale application of ferrate(VI) in the water industry owing to difficulties associated with the relatively low yield of ferrate(VI), the instability of the chemical depending on its method of preparation, and the lack of adequate studies that have demonstrated its capabilities and advantages over existing water and wastewater treatment methods. Fundamental study is thus required to explore the new preparation methods focusing on increasing the production yield and product's stability and avoiding using hypochlorite or chlorine as the oxidant. Also, the application of ferrate(VI) in drinking water treatment has not been studied systematically and future work in this field is recommended.