Electrochemical Ferrate(VI) Synthesis with Cast Iron Shavings and Its Potential Application for Household Graywater Recycling

Abstract

This paper deals with a laboratory-based investigation for the treatment of graywater generated from public housing in Turkey. In the first part of the study, ferrate(VI) has been synthesized electrochemically. The current efficiency (CE), energy consumption (EC), and ferrate(VI) yield during the electrochemical synthesis of ferrate(VI) was measured using cast iron shavings as anode materials. In terms of the highest CE, the lowest EC, and ferrate(VI) yield, 16-M NaOH media, applied current of 3 A, and 9 min of electrolysis time were found as optimum conditions for electrochemical synthesis of ferrate(VI) with cast iron shavings. This reactor configuration with cast iron shavings provided much higher CE values compared with the other studies. Ferrate(VI) was quite effective for the removal of constituents in graywater. Applying 75 mg/L ferrate(VI) dose at pH 7 was successful at removing organic pollutants and total coliforms (TCs). Besides, more than 73% anionic surfactant degradation was achieved at the same conditions. According to reuse regulations, treated graywater by electrosynthesized ferrate(VI) can be used for unrestricted reuse options. Additionally, the greater removal of organics by ferrate(VI) reduced the potential of bacterial regrowth and additional chemical disinfectant demand.