Optimization And Application Of High Sulfate Source Water Treatment Process Based On Ion Exchang

Gradually,sulfate has become one of the main pollution indexes of water sources in our country.The excessive concentration of sulfate will affect the drinking,transportation and water environment.In this paper,surface water with high sulfate concentration in a region of Ningxia was taken as the research object,flocculation adsorption filtration was used as the pretreatment measure,and ion exchange resin was used as the core treatment technology to determine the main process parameters of pretreatment.In addition,the sulfate removal effect of four representative commercial ion exchange resins was evaluated,and the operation parameters and regeneration conditions of ion exchange resins were optimized for the target water source.Finally,the field pilot test was carried out,and the innovative nanofiltration salt technology was adopted for the safe disposal and reuse of ion exchange resin regeneration waste liquid.Firstly,the main water quality parameters of the target source water and their seasonal variation rules were analyzed,and the final treatment requirements of reducing sulfate concentration and turbidity were determined,while controlling COD_Mn.Combined with the characteristics of raw water quality and the research status at home and abroad,flocculation adsorption filtration is determined as the pretreatment process,the ion exchange technology is the core process,and the application form of ion exchange resin is determined to be-HCO₃^-type ion exchange resin.In the microflocculation adsorption filtration link,the optimal dosage of coagulant was 8 mg/L（Fe Cl₃:PAC=1:1）,and the water temperature was increased to 10mg/L when the temperature was below 10℃.The adsorption column can effectively trap the flocculated floc.After being filtered by a double-layer filter with homogeneous quartz sand and activated carbon,the turbidity of the effluent is stable at less than 1 NTU,the COD_Mn is controlled at about 1.8 mg/L,and the backwash cycle of the filter is 22-36 h.Four common commercial ion exchange resins were compared and selected,and it was found that they were suitable for drinking water treatment,and effectively replaced sulfate in water by ion exchange process.Under the condition of bicarbonate as the exchange group,the four ion-exchange resins show the preferential selectivity of sulfate and the low affinity of organic matter.Sulfate exchange capacity from high to low is D201 ion exchange resin,WSD235 ion exchange resin,201x7 ion exchange resin,D301 ion exchange resin.When the actual raw water was treated,the sulfate capacity was slightly reduced,the optimal water transfer ratio was 170 BV,and the contact time was 5min,which could fully remove the sulfate in the raw water.The optimal regeneration condition was the countercurrent regeneration of 4 BV7%sodium bicarbonate solution for 1.5 h,and D201 ion exchange resin showed the best performance.Secondly,this study constructs a complete actual treatment system with a scale of 50m³/h for the target raw water,and defines the device combination process for the actual high sulfate source water,including micro-flocculation adsorption filtration,ion exchange,waste water reuse and recycled waste liquid disposal system.On the basis of the pilot test,the paper verifies and further optimizes the ion exchange resin in the treatment of raw water three phases of moisture:the removal of sulfate and chloride ions is stable;The removal of sulfate was stable,and the removal of chloride ion gradually decreased.Chloride ion release,sulfate removal gradually reduced.It was found that the actual sulfate capacity of high sulfate raw water was 51.5 mg/L,and the optimal water multiple was 170 BV.In the process of adjusting the mixing ratio to 3:2and gradually decreasing,the total treated water reaches 400BV in the long run in the course of the line,the water quality meets the standard and the operation is stable.Finally,the efficiency of the four commercial nanofiltration membranes for the treatment of recycled liquid was above 98%.Aove NF60-4040 nanofiltration membrane had the lowest retention rate of bicarbonate,showing the best salt-separation efficiency and the highest water flux.Using secondary nanofiltration to treat regenerated waste liquid,75%of water and more than 68%of regenerated agents could be recovered.Combined with evaporation crystallization technology,all resources can be recovered to achieve"zero emission".After long-term operation,the membrane flux can be effectively recovered by alkali washing+pickling,which reduces the total operation cost of the process to 0.6165 yuan/cubic meter.Through this study,all water and salt resources have been recovered successfully,which is friendly to the environment.It provides a new feasible scheme and reference for the centralized small water supply of high sulfate source water and the emergency water supply.In summary,this study optimized the parameters of ion exchange process by analyzing the sulfate removal ability,regeneration conditions and related influencing factors of ion exchange resin.Combined with micro-flocculation adsorption filtration pretreatment and nanofiltration waste treatment technology,effective treatment and resource recovery of high sulfate source water were realized.This provides a reference of academic value and practical value for the treatment of high sulfate source water.