Research On Deep Purification Wastewater Treatment Which Contains Uranium Fluoride

With the development of the nuclear,a number of waste water containing Fluorine and Uranium was produced and which was difficult to disposals.This study focused on waste water containing Fluorine and Uranium,the biological deposition,chemical sedimentation and ion-exchange fiber(IEF)method was used to deep purification of Fluorine and Uranium,and we proposed one economical and feasible purification process of Fluorine and Uranium.The Immobilized live Deinococcus radiodurans(IDR)was used to study biological fixation,and results showed that while the bacteria content was 2.5%,the Settlement properties of Uranium was good,when the initial Uranium concentration was 50 mg/L,the removal rate was up to 95% and the maximum adsorption capacity was 103.82 mg/g at p H 4.The dynamic column adsorption experiment of IDR showed that stability of Uranium removal was good,after adsorption,the Uranium was easily regenerated by 0.1 mol/L HCl and the desorption rate was more than 90%,which could be used as fixed bed packing considerations.The SEM,EDS and XRD analysis showed that Uranium which exists on the surface of IDR particles was Uranium phosphate,after ashing treatment,the weight loss ratio was 254,the Uranium in ash was Ca(UO2)(PO4)·3H2O and(Ca,U)(PO4)·2H2O.The results of chemical sedimentation of Uranium showed that at p H 9,10% ethanol and 3 g Calcium dihydrogen phosphate been added,the removal rate of Uranium was more than 95%,the SEM and EDS analysis showed that the precipitation was 5~10 μm lamellar particles and composed of Ca,P,U,O four elements,when at p H 9,10% ethanol and 3 g Calcium dihydrogen phosphate been added,the U(HPO4)2·6H2O was easy to formed,when at p H 7,30% ethanol and 3 g Calcium dihydrogen phosphate been added,the(UO2)3(PO4)2·8H2O was easy to formed.The Calcium salt was used to study chemical precipitated fluoride,and the Fluoride ion concentration could be reduced to about 30 mg/Lwhen Fluoride concentration was 130% theoretical values of calcium salts,while adjust the p H=11 and added phosphate according to the ratio of 2:1 phosphate: fluoride ion,then the concentration of Fluoride ions could be reduced to about 5mg/L,which can reach the level of emission.The optimized static test of IEF remove Uranium results showed that strong base type fiber(SAIEF)had optimal treatment effect in the pure Uranium system when pretreated by acid washing method and the contact time was 15~30 min,the Uranium removal rate can reach more than 90%,and when the p H at 10.5,dosage was 1.5g/100 mL and initial concentration of Uranium was 20~100mg/L,the SAIEF had the best removal of Uranium.The 50 mg/L Uranium could be reduced to less than 0.05 mg/L when dosage constant and gradient descent 3 times.The desorption effect was better when 0.1M hydrochloric acid was used to desorption agent,and the concentrated water after desorption can be recovered by chemical deposition.SAIEF maintains the same adsorption capacity of Uranium in pure Uranium and Uranium Fluoride mixed system while Fluorine ion concentration was 5g/L,10g/L,15g/L,respectively and corresponding to 5mg/L U and 50mg/L U,the SEM,EDS and FTIR analysis showed that the main ion exchange equation of SAIEF as followed:P-CH2N+(CH3)3Cl-+(UO2)2CO3(OH)3-→[P-CH2N+(CH3)3](UO2)2CO3(OH)3 + Cl-(p H 8~11.5)P-CH2N+(CH3)3Cl-+ UO2(OH)3-→[P-CH2N+(CH3)3]UO2(OH)3+ Cl-(p H 10~14)The results of SAIEF dynamic column test showed that in pure Uranium system,the saturated adsorption capacity of SAIEF for Uranium was about 426.7mg/g when the flow rate was 10~20mL/min,when the packing density was 0.1g/mL,packing height was 10~20 cm;the ratio of diameter to height was 1:3~6,the influent concentration of Uranium was 2~50mg/L,into of water was 30-60 column volume,then can ensure the concentration of Uranium in effluent water at 10 h below 0.05 g/L,which meet the deep purification requirements,and height-diameter ratio have little effect on Uranium removal at this velocity,when dynamic desorption,volume flow rate by half and used 3 times column’s 0.1M or 10% hydrochloride or sodium chloride can be completed,when the flow rate was 25ml/min,using three tandem mode,packing density was 0.1g/mL,filler height was 20 cm,the ratio of diameter to height is 1:7.6,Uranium concentration in water was 50mg/L,total water volume was 120 columns,then can ensure the concentration of Uranium in effluent water at 10 h below 0.05 g/L.When the influent Uraniumconcentration was 5mg/L and the total volume of water was about 1050 column volumes.,then can ensure the concentration of Uranium in effluent water at 28 h below 0.05 g/L.The main components in the ash of the fiber after adsorption was UO4·4H2O,and the weight loss ratio was about 6.5.In the Uranium Fluoride mixed system,when the flow rate was 10~20mL/min,using two tandem mode,packing density was 0.1g/mL,filling height was 10 cm;the ratio of diameter to height was 1:6,the influent Uranium concentration was 50mg/L,the influent Fluorine concentration was 10g/L,total water volume was 120 columns,then can ensure the concentration of Uranium in effluent water below 0.05 g/L and maintained the Fluoride concentration at about 10g/L,when using three tandem mode,packing density was 0.1g/mL,filling height was 20 cm;the ratio of diameter to height is 1:7.6,the influent Uranium concentration was 50mg/L and 5 mg/L,the influent Fluorine concentration was 10g/L,then can ensure the concentration of Uranium in effluent water at 8h below 0.05 g/L and maintain Fluoride ion concentration to the influent concentration.The two amplification test of SAIEF unit was carried out in the pure Uranium system,and the results showed that when the influent Uranium concentration was 5~100mg/L,the flow rate was 5~100L/h,the ratio of diameter to height was 4:1,packing density was 0.1 g/mL,using four tandem mode,then can complete reach the deep purification of Uranium and the decontamination factor was up to 3.762×105,at the same time,the SEM analysis of long-term used of SAIEF showed that the fiber after repeated used,the structure of fiber was intact and no disintegration phenomenon,and the EDS showed that the content of Cl increased,which indicated that the functional groups of the fibers were normal,and the exchange capacity was further optimized during the repeated use.Based on the research,this study presents a economical and feasible process for the purification of wastewater containing Fluorine and Uranium,which based on settlement method with SAIEF technology,and it provided a reference for the treatment of Fluoride and Uranium wastewater in nuclear industry.