Optimization Of Treatment Of Low Concentration Chlorine Containing Wastewater By Chemical Modification In Electrosorption Electrode Materials And Lime Aluminum Precipitation Process

Inorganic chloride is a corrosive ion.Chloride ion will not only accelerate the corrosion of pipelines and devices,affect the efficiency of water reuse,but also threaten the aquatic organisms to cause ecosystem damage and harm to human health.Therefore,the study on the removal of chloride ion in the wastewater can increase the reuse rate of industrial wastewater and relieve the pressure of water shortage in China.In this paper,two kinds of environmentally friendly and low energy consumption dechlorination methods,electrosorption and ultra-high lime aluminum method,were discussed.In order to enhance the deionization effect of capacitor,different chemical activators were used to chemically impregnate activated carbon,which were used as electrode materials for electrosorption.For ultra-high lime aluminum method,the effects of the proportion of aluminum salt and calcium salt,the reaction time,the reaction temperature of the system and the concentration of chloride ion on the chloride removal were studied.The treatment effect of the two methods was compared,and the process conditions of the two methods were optimized.The two methods were applied to the actual wastewater treatment experiment.When phosphoric acid,nitric acid,urea,melamine and zinc chloride were used as chemical modifiers,the surface morphology,chemical bond and element composition of the modified activated carbon changed,the specific surface area decreased,the specific capacitance increased,and the zero charge potential increased positively.The results showed that the chemical modification was beneficial to the rapid ion diffusion process and strong corrosion resistance The process of capacitance deionization of the electrode coated with activated carbon was enhanced.In particular,the desalination capacity of phosphoric acid modified activated carbon electrode in 500 mg/L NaCl solution at 1.4 V is 15.5 mg/g,about 8.0 times of that of unmodified activated carbon electrode(2.5 mg/g);the regeneration performance,charging efficiency and energy consumption of modified activated carbon electrode are better than unmodified activated carbon coated electrode.The method of ultra-high lime aluminum can effectively remove the chloride ion from the solution.When the molar ratio of calcium aluminum chloride is 5:3:1 and the reaction time is 40 min at 40?,the removal rate of solution containing 500 mg/L of chlorine can reach 70.1%.Adding NaClO2 and CaO twice can obviously improve the removal efficiency of chloride ion,and the maximum removal rate can reach 80.5%.