Research On Treatment Of Simulated Radioactive Wastewater Containing Iodine And Strontium

With the rapid development of the nuclear industry,the risk of drinking water being contaminated by radionuclides increases.Radioactive iodine and strontium nuclide are the main parts in contaminated water.Therefore,the removal of radioactive iodine and strontium in emergency treatment has become one of study hotspots in the field of water treatment.In this paper,a chemical precipitation-microfiltration combination process was tested to study the iodine removal in a pilot-scale test,and the iodine and strontium removal tests were conducted with a single-stage ultra-low pressure reverse osmosis membrane process.The research results are as follows:In the iodine removal pilot-scale test by chemical precipitation-microfiltration combination process,the designed treatment capacity was 20 m³/d.The effect of the dosage of Na₂SO₃as the oxygen scavenger on the iodine removal effect was studied.When the dosage of Na₂SO₃was 150 mg/L,the removal rate of I^-was only 89.72%during stable operation,and the Cu Cl consumed in the reaction was only 37%.When the dosage of Na₂SO₃increased to 200 mg/L,the removal rate of I^-was 95.80%during stable operation.At this time,the Cu Cl consumed in the reaction reached 73%,and the degree of membrane fouling was also lower.It was indicated that increasing the dosage of Na₂SO₃could not only improve the removal rate of I^-,but also alleviate membrane fouling to a certain extent.In the iodine removal test by the single-stage ultra-low pressure reverse osmosis membrane process,the recovery rate maintained at about 15%.Within the scope of the study,it was found that the smaller the influent pressure,the lower the p H and the greater the initial I^-concentration were beneficial to increase removal rate of I^-.The optimum level conditions were determined by the orthogonal experiment:the pressure was 0.3 MPa,the initial I^-concentration was 50 mg/L,and the p H was 3.At this moment,the removal rate of I^-was 98.22%at the maximum.The influence level of single factors on the I^-removal effect was:initial I^-concentration>p H>pressure.In the strontium removal test by the single-stage ultra-low pressure reverse osmosis membrane process,the recovery rate of the whole system was 90%at the end of the operation.Within the scope of this study,the decontamination factor（DF）increased with the inlet pressure increasing.When the initial Sr²⁺concentration was10 mg/L,the DF was the largest.When the p H was 4,the DF was the lowest,and the strontium removal effect was the worst.As p H increased,DF also became larger,and when p H was 9,the DF reached a maximum of 734.The optimum level conditions were determined by orthogonal test:the pressure was 0.76 MPa,the initial Sr²⁺concentration was 10 mg/L,and the p H was 9.The influence level of single factors on the strontium removal effect was:p H>initial Sr²⁺concentration>pressure.Coexisting ions in the tap water were beneficial to improve the removal of strontium ions.