Simultaneous removal of Ni(II) and fluoride from a real flue gas desulfurization wastewater by electrocoagulation using Fe/C/Al electrode

Abstract

Large amounts of anions and heavy metals coexist in flue gas desulfurization (FGD) wastewater originating from coal-fired power plants, which cause serious environmental pollution. Electrocoagulation (EC) with Fe/C/Al hybrid electrodes was investigated for the separation of fluoride and nickel ions from a FGD wastewater. The study mainly focused on the technology parameters including anode electrode type, time, inter-electrode distance (5–40 mm), current density (1.88–6.25 mA/cm2) and initial pH (4–10). The results showed that favorable nickel and fluoride removal were obtained by increasing the time and current density, but this led to an increase in energy consumption. Eighty-six percent of fluoride and 98% of Ni(II) were removed by conducting the Fe/C/Al EC with a current density of 5.00 mA/cm2 and inter-electrode distance of 5 mm at pH 4 for 25 min and energy consumption was 1.33 kWh/m3. Concomitant pollutants also achieved excellent treatment efficiency. The Hg, Mn, Pb, Cd, Cu, SS and chemical oxygen demand were reduced by 90%, 89%, 92%, 88%, 98%, 99.9% and 89%, respectively, which met stringent environmental regulations.