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

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/cm(2)) 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/cm(2) and inter-electrode distance of 5 mm at pH 4 for 25 min and energy consumption was 1.33 kWh/m(3). 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.