Research Of Capacitive Deionization Technology On Reuse Treatment Of Reverse Osmosis Concentrated Water

At present,the scarcity of fresh water has pose a serious threat to human development.Reverse osmosis technology is widely used in the fields of seawater desalination,industrial boiler feed water preparation,and wastewater deep reuse because of its mature,reliable,high efficiency and economical advantages.However,in the production of pure water,the water quality is more complicated and the salt content is more.High by-product concentrated water.Due to environmental protection requirements and the shortage of water resources and zero emissions,the rational treatment and resource utilization of concentrated brine has become a new problem in the application process of reverse osmosis technology.Capacitor deionization technology has the advantages of low energy consumption,high concentration multiple,no environmental pollution,etc.It is a water treatment technology with great potential and far from being mature.At present,there is no relevant research report on the application of capacitive deionization technology to the reverse treatment of reverse osmosis concentrated water.This paper mainly focuses on the reduction treatment of zero-emission of reverse osmosis concentrated water,and uses the self-made capacitor deionization small test device to explore the treatment effect.And optimize the desalting conditions;for the reverse osmosis concentrated water of three different water quality,study the applicability of reverse osmosis concentrated water;explore the treatment effect of reclaimed water quality and pH on reverse osmosis concentrated water.The main conclusions and results of this study are as follows:The self-made capacitor deionization test device has an effective electrode plate area of 16O×80mm.It is designed with a uniform water distribution device,which can adjust and optimize the coating thickness and the plate spacing and coating materials.(1)The results of orthogonal test of capacitive deionization device show that the influence of the electrode coating thickness is significantly higher than the influent flow rate and the working voltage.In the case where the electrode coating thickness is 0.8 mm,the influent flow rate is 38 mL/min,and the working voltage is 1.0 V,the total hardness in the adsorption saturation cycle and the saturation adsorption amount of the Cl-unit electrode can reach 51.18 μmol and 2.31 μmol,respectively.(2)Based on the orthogonal test,the basic parameters of the small test device were optimized.Under the conditions of influent flow rate of 38 mL/min,working voltage of 1.0 V and electrode coating thickness of 0.8 mm,the best desalination effect can be ensured.Reduce production costs.Moreover,the amount of adsorption of each ion by the activated carbon electrode per unit volume of the capacitor deionization device is:Mg2+>Ca2+>Na+,indicating that the removal effect of divalent ions by the capacitor deionization device is better than that of monovalent ions.(3)Under the best working conditions,the deep well water reverse osmosis concentrated water continuously runs five saturated working cycles.According to the experimental treatment results,the saturated adsorption capacity of each ion unit electrode is 1/2Ca2+:45.16 pmol,1/2Mg2+:122.17 μmol,Na+:34.98 μmol,Cl-:41.86μmol,and the amount of ion saturation adsorption is basically unchanged in each working cycle,which indicates that the reverse deionized concentrated water in the capacitor deionization device has the advantages of stable operation and good electrode regeneration effect.(4)The plate spacing increases from 1 mm to 2 mm,the amount of sodium ion adsorbed per unit volume of electrode material increased from 40.98 μmol to 44.99μmol,increased by 4.01 μmol,and the adsorption amount of Ca2+and Mg2+is decreased,indicating that the plate spacing can be increased within a certain range.The adsorption amount of sodium ions increases the adsorption selectivity of the electrodes to ions.(5)Under the best working conditions,the capacitive deionization device treated the seawater desalination reverse osmosis concentrated water and the diluted seawater desalination reverse osmosis concentrated water per unit volume electrode total hardness saturation adsorption amount was 98.28 μmol and 71.87 μmol,respectively,and found that the influent The higher the salt content,the better the removal of ions.(6)In the study of regeneration effect,it is found that the lower the salt content of the regenerant,the higher the adsorption amount of each electrode per unit volume of the electrode material during the next adsorption cycle,which can enhance the regeneration effect,but in practical applications,the reverse osmosis concentration cannot be achieved.The purpose of water reduction is not in line with the actual application value.The acid regeneration liquid can significantly improve the electrode regeneration effect,thereby improving the desalination efficiency of the electrode.(7)Preliminary design study of industrial equipment,using multiple adsorption modules in parallel,each adsorption module uses high-efficiency functional materials as electrodes.Each set of electrode design dimensions is:500 mm×300 mm×2 mm.The adsorption module design size is:510 mm×320 mm×25 mm,which adapt to the treatment of high water and different water quality reverse osmosis.