Experimental Study On Desalinated Seawater Mineralization Based On Different Natural Mineralized Materials

Desalination can effectively solve the problem of water shortage,but it is not suitable for drinking because of its low mineral content..After desalinated seawater enters the municipal pipes network,red water may appear due to its low alkalinity,low hardness and other quality characteristics.In order to improve the mineral content in desalinated seawater and reduce the erosion of desalinated seawater on the pipes network,this paper studies the desalination of seawater by dissolving natural mineralized materials without adding any chemicals,designing beaker experiment and packed column experiment,and studies the influence of different factors on the mineralization effect.(1)The data of static experiment show that the longer the soaking time is in a certain time range,the more elements are dissolved out of medical stone,tourmaline and shell which all precipitate metasilicic acid.And the shell has a beneficial element of strontium element precipitation,and its total solidity,alkalinity and total hardness of the shell group are increased greatly.(2)In stirring experiment,due to short soaking time and near-neutral conditions,the amount of elements dissolution is relatively low and the difference is not significant;there is no metasilicic acid precipitation in the three mineralized materials under this condition;the shell has the precipitation of a beneficial element of strontium element,but the amount of elements precipitated is significantly reduced.(3)The experimental results of a single mineralized material packed column show that reducing the flow rate and increasing the hydraulic retention time are beneficial to the dissolution of mineral under the conditions of low p H.The dissolution effect of medical stone and tourmaline in the packed column experiment is poor,and the dissolution effect of shell is very good.The total hardness of the two groups of shell exceeds ?the Standards for drinking water quality?(GB5749-2006)(?450mg/L).Metasilicic acid dissolution is the best in medical stone,followed by tourmaline and shell.The dissolution of metasilicic acid in medical stone is 27-38 mg/L,which reached ?National Food Safety Standards Drinking Natural Mineral Water?(GB8537-2018)(>25mg/L).There is no strontium dissolution in medical stone and tourmaline.The amount ofStrontium in shell is 0.8-6.1 mg/L,which reached ? National Food Safety Standards Drinking Natural Mineral Water?(GB8537-2018)(>0.2mg/L).(4)The experimental results of two kinds of mineralized material packed columns show that the tourmaline releases negative ions and promotes the dissolution of various ions in the shell.The combination of tourmaline and shell is the most soluble in the amount of elements dissolution,and the combination of shell and medical stone is the second.The dissolution of the medical stone and the tourmaline group is the least.The amount of strontium in the combination of tourmaline and shell is 2-8 mg/L,the combination of shell and medical stone is the same Dissolution amount of two combinations reachs?National Food Safety Standards Drinking Natural Mineral Water?(GB8537-2018)(>25mg/L).(5)The experimental results on three kinds of mineralized material packed columns show that,with the increase of the proportion of medical stone and shell,the dissolution of soluble total solid,total hardness,alkalinity,metasilicic acid and strontium increased with the addition of appropriate tourmaline.The dissolution of strontium in the experiment is 4.5-5mg/L,all of which reached ?National Food Safety Standards Drinking Natural Mineral Water?(GB8537-2018)(?0.2mg/L).(6)The surface morphology of medical stone,tourmaline and shells before and after mineralization was observed by scanning electron microscopy,the surface of medical stone is uneven,which is beneficial to increase the contact area of water,but the erosion process is slow,and the mineral dissolution of medical stone is relatively low.The internal structure of tourmaline has not changed and the amount of mineral dissolution is low.The whole shell and the single prism are involved in the erosion process,becoming jagged and uneven.The water erosion traces are obvious and the prism gap becomes larger,the contact area with water increases,and the mineral dissolution amount is high.(7)Rezna stability index analyzes experimental effluent water quality stability and indicates that the stability of mineralized water with added shell material is significantly enhanced.If the p H of the effluent is subsequently adjusted,the experimental effluent of the shell group can reach a steady state.