Effect Of Centrifugation And Filtration On The Removal Of Typical Ions From Highly Concentrated Sea Ice

Desalination,as an effective means to increase water resources from the source,is a strategic choice to solve the scarcity of freshwater resources.With the continuous expansion of seawater desalination scale,two mainstream technologies,represented by reverse osmosis and low-temperature multi-effect,have been gradually formed.However,the by-product of the treatment process,concentrated seawater,has a salt content as high as 65-85 g/L and contains a large number of chemical substances,which may damage the ecological environment if not treated properly.The current disposal methods for concentrated seawater include direct sea discharge,deep well injection,direct discharge into surface water or sewage treatment systems,which not only threatens the fragile ecological environment but also wastes the valuable chemical resources in concentrated seawater.Therefore,it is important to study the treatment of concentrated seawater as a by-product of desalination.In this paper,the effect of different melting methods on the removal of typical ions from concentrated seawater is investigated.In the first part,the effect of different melting methods on the pre-removal of typical ions in simulated concentrated seawater is investigated based on the freezing method:the effect of different ice forms on the pre-removal of typical ions in simulated concentrated seawater is investigated,and the effect of centrifugation and filtration on the pre-removal of typical ions in simulated concentrated seawater is analyzed;in the second part,the effect of centrifugation（different time and speed）and filtration（different time and pumping flow）on the pre-removal of typical ions in simulated concentrated seawater is investigated.The second part investigated the effect of centrifugation（different time and speed）and filtration（different time and pumping flow）on the removal of typical ions in simulated concentrated seawater;the third part investigated the effect of centrifugation and filtration melting on the removal of typical ions in actual concentrated seawater.The results of the experiments are as follows:（1）In the pre-melting of the ice body,the removal effect of crushed ice on each ion is better than the removal effect of whole ice melting,the removal effect of different melting methods on ions is:centrifugal melting>extraction melting>crushed ice melting>whole ice melting,in the case of the same volume of melt water,the action of the applied force can accelerate the melting of ions in the melting process,which is conducive to the improvement of the removal rate;the removal effect of different ions under the same conditions is:Cl^->K⁺>Na⁺>Ca²⁺>Mg²⁺>SO₄^2-.（2）The longer the centrifugation time and extraction time,the lower the melting efficiency of conductivity,TDS,salinity,K⁺,Na⁺,Ca²⁺,Mg²⁺,Cl^-,SO₄^2-,and the higher the melting rate and removal rate;with the increase of centrifugal speed,the melting efficiency,melting rate and removal rate gradually increased;the higher the extraction flow rate,the melting efficiency first slowly decreased and then gradually increased,and the melting rate and removal rate gradually increased;the removal rate per unit volume of centrifugal melting was smaller than that per unit volume of extraction melting;the removal effect of increasing the centrifugal speed during centrifugal melting was better than the removal effect of increasing the centrifugal time.（3）The removal rate per unit volume of centrifugal melting is smaller than that of extraction melting;the promotion effect of centrifugal melting and extraction melting on ion melting is:extraction melting>centrifugal melting>natural melting;the treatment effect of simulated concentrated seawater under centrifugal melting condition is better than that of actual concentrated seawater,and the treatment effect of high concentration of ions in actual concentrated seawater under extraction filtration condition is better than that of simulated concentrated seawater.