Electrochemical Treatment of Wastewater from the Flue Gas Desulfurization Process

Abstract

In the case of Flue Gas Desulfurization(FGD) wastewater, which has good conductivity and contains chloride ions, electrochemical methods was supposed to be very effective because the organic pollutants are oxidized either by direct oxidation at the electrode-solution inter phase or by indirect oxidation in the bulk of the solution. As a supporting electrolyte and the source of chloride reactant, NaCl is generally added for the electrochemical oxidation process. In this study, FGD wastewater has a lot of chloride which is provided as reactant for the electrochemical oxidation. It was ultimately intended to omit the artificial addition of electrolyte solution and decrease the pollutant loading efficiently on the post electrochemical oxidation process in order to improve the performance of organics removal. Due to the strong oxidizing potential of the chemicals produce, the effluent COD and T-N is reduced substantially in this treatment technique. The influence of effluent initial concentration, pH, supporting electrolyte concentration and the anode material on pollutant degradation has been critically examined. It was found that, during oxidation, a polymeric film was formed in the potential region of water stability, and that it was removed by anodic polarization at high potentials in the region of O₂ evolution. Bulk electrolysis results showed that the electrochemical process was suitable for removing COD and T-N in wastewaters, due to the production of hydroxyl radicals on the electrode surface. The titanium coated with IrO₂ electrode is a metal oxidation electrode. It was found to be a good material to be used as anode and cathode. It is not corrosive, mechanical, easily to be microminiaturization, uneasy to be polluted, can be used under high temperature and high volt solution. And the respond rang is large. So it brings about a lot of interests.