Experimental Study On The Treatment Of Cl~- In Desulfurization Wastewater Based On Electrolysis

Limestone-gypsum wet flue gas desulfurization(WFGD)technology has become the most widely used flue gas desulfurization technology in coal-fired power plants because of its mature technology,stable operation,and high desulfurization efficiency.The waste water produced from Wet flue gas desulfurization(WFGD)system in power plants is characterized by weak acidity,high salt content,high suspended solids,high chlorine content,and high heavy metals.Besides,the water quality can fluctuate obviously.Therefore,it is difficult to handle and reuse the waste water.Domestic and foreign coal-fired power plants mostly adopt the triple box method to treat the desulfurization wastewater.This method can effective remove the suspended solids and heavy metal ions,but its removal of soluble salts leaves much to be desired.The concentration of chloride ions in the treated water is still high.In view of this problem,a membrane electrolysis method was proposed for advanced treatment of wastewater so as to realize the reuse of wastewater and the resource utilization of chlorine.A two-chamber ion-exchange membrane electrolyzer was designed and set up in the laboratory.Sodium chloride solution with different concentrations was used as the simulated desulfurization wastewater in the electrolysis experiment.The single factor experiment was used to investigate the effect of different electrolysis factors(electrolysis temperature,electrolysis time,current density,electrolysis voltage,electrode spacing,electrolyte concentration and air blowing way)on the electrolysis effect.The relationship between current efficiency,desalination rate and power consumption with time was compared by recording the voltage and electrolysis current and the concentration of chloride ion in water samples at different time points.Experimental results showed that using electrolysis pretreatment can effectively remove the chlorine ions in the water.The desalination rate can reach more than 95%with stirring disturbance for 300min at an electrolysis temperature of 40°C when the plate spacing was set to 2cm,the current density was 66.7mA/cm~2 and the initial anolyte concentration was 30 g/L.The treated water can be used as process water continues to be reused.Finally,the mechanism of membrane electrolysis treatment of desulphurization wastewater was investigated from the aspects of the selection and transmission mechanism of ion membrane,the basic principle of electrolysis,the analysis and calculation of cell voltage,and the main electrochemical reaction of desulfurization wastewater treatment by membrane electrolysis.The research content of this topic provides support for electrolysis treatment of wet flue gas desulphurization wastewater.