Application of electrochemically synthesized ferrate(VI) in the purification of wastewater from coal separation plant

Abstract

The oxidative and coagulation efficiency of Na2FeO4 solution, electrochemically generated by trans-passive anodic oxidation of electrical steel in 10M NaOH solution, is confirmed in the process of purification of heavily contaminated wastewater from coal separation plant. The decontamination efficiency is evaluated comparing the values of selected contamination parameters obtained by chemical and biochemical analysis of plant effluent water and water obtained after decontamination with ferrate(VI) solution in relatively simple laboratory procedure. The sample of 450 ml of wastewater is treated in laboratory conditions with 100cm3 solution of 1 mg dm-3 Na2FeO4 in 10M NaOH. The chemical analysis of effluent water after treatment have shown almost 3 times lower permanganate index, about 3 times lower iron content, 1.45 times lower As3+ content, 7.35 times lower ammonia content. Turbidity and chemical oxygen demand (COD) is reduced for more than 5.77and 13.4 times, respectively. The suspended and colloid matter is eliminated from effluent water after treatment with ferrate(VI) solution. Also, biochemical exploration has confirmed high efficiency of ferrate(VI) in organics and microbial elimination showing 7.1 times lower 5-days bio-chemical oxygen demand (BOD5), and total elimination of aerobic and anaerobic bacteria from effluent water. According to standards on quality of industrial wastewater effluents, it may be concluded that ferrate(VI) treatment of wastewater almost completely eliminates excess of dangerous chemicals and pathogen bacteria, with the exemption of arsenic. Thus, ferrate(VI) shows capable performance in treatment of coal separation plant wastewater.

Keywords

• ferrate(VI)
• electrochemical synthesis
• wastewater
• coal separation
• purification
• disinfection