The role of potassium ferrate(VI) in the inactivation of Escherichia coli and in the reduction of COD for water remediation

The use of potassium ferrate(VI) as an alternative water remediation chemical has been studied and is reported in this paper. The water remediation performance of potassium ferrate(VI) was evaluated in comparison with sodium hypochlorite, ferric sulphate (FS) and aluminium sulphate (AS). The effects of the dosages of ferrate(VI), hypochlorite and FS/AS and solution pH were investigated. A model water with Escherichia coli (E. coli) number concentration of 3.2×108/100 ml was used to examine the comparative disinfection performance and a real sewage sample was used to assess the comparative coagulation performance. The study demonstrated that the potassium ferrate(VI) performed superior to sodium hypochlorite in the inactivation of E. coli; less ferrate(VI) dose and contact time were required to achieve the same E. coli killing efficiency, the disinfection performance was less affected by the solution pH, and the disinfection rate of the ferrate(VI) was faster than that with sodium hypochlorite. In sewage treatment, ferrate(VI) performed superiorly as a oxidant and a coagulant; it can reduce 30% more COD, and kill 3 log more bacteria in comparison with AS and FS at a similar or even smaller dose.