Research On Electrosorption Desalination Technology In Wastewater Treatment

To alleviate the severe shortage of fresh water resources in our country,The development of wastewater reuse and advanced wastewater treatment is urgent.In wastewater reuse,it is necessary to carry out desalination treatment.Traditional salt technology has a lot of problems such as high processing cost,difficult to regeneration,easy to cause secondary pollution and so on.The electrosorption desalting device has the advantages of simple manufacture,easy to get electrode materials,easy to use in practice and regeneration.Therefore,this paper used the self-made electrosorption desalting device,investigated the basic properties and operating parameters of electro-adsorption desalination technology,in order to provide technical support to the large-scale application of electric absorb technology.Research shows:It is effective that electrolyte ions in saline solution could be adsorbed by electrosorption.When the electrode voltage is 1.6 V,the plate spacing is 0.8 cm,the initial concentration is 800 S/cm and influent flow is 20 mL/min,the desalting rate can reach 57.6%.The response surface experiment point out that the significant factors are influent flow,plate spacing and electrode voltage in turn.There is interaction between the impact factors,It is obvious between plate spacing and electrode voltage.Analysis of electrosorption characteristics of ACF shows that electric voltage is increasing in the adsorption process but the current decreases gradually.The process of adsorption and backwashing after 400 min can ensure the regeneration of electrode materials,after 5electrosorption cycle,electrosorption remained at a relatively high level.Electrosorption conforms to Freundich adsorption model and Lagergren quasi two order kinetic equation.The adsorption effect of different cations is related to the ionic radius and the number of charges,smaller ionic radius,more charge number,the adsorption efficiency is high,the removal rate shows that Fe³⁺>Mg²⁺>Ca²⁺>Na⁺>K⁺.Electrosorption effect of different halogen anions depends on the size of the ionic radius,namely the final removal rate shows that Cl^->F^->Br^->I^-.The ACF modified by heat treatment can significantly improve the content of microporous electrode material and electrode surface area.Alkali modification reduces the oxygen content of functional groups on ACF surface and adsorption capacity change is unlikely.In acid modification,H₂O₂ is better than HNO₃,acid modification increases the adsorption capacity of ACF,it is better than alkali modification.HNO₃-heat treatment has best modification effect,The desalination rate increases from 57.6%to 69.8%,the adsorption capacity increases from 7.5 mg/g to 9.76 mg/g.The research of the advanced treatment to actual refining wastewater shows that various water quality indicators has good treatment effect,Treatment efficiency ranking from high to low is Cl^->TDS>SO₄^2->Mg²⁺>Ca²⁺>hardness>NH₄-N>COD_cr,In addition to COD_cr and NH₄-N,the removal rate of other quality indicators is above 50%.Adding a certain amount of Na Cl contributes to the adsorption removal of TDS,Cl-,COD and NH₄-N.