Pilot-scale Test On Removal Of Strontium From Simulated Radioactive Water By Prilling-Membrane Technology

In this dissertation,the pilot-scale experiment using a hybrid process of prilling and membrane separation was carried out to explore the stabilities and removals of strontium in drinking water.Compared to the combined process of chemical precipitation and membrane separation,the process based prilling could improve the solid-liquid separation and reduce the membrane fouling rate.It would be applied in the treatment of radioactive drinking water caused by nuclear accidents.During the prilling,calcium carbonate and sodium carbonate were respectively used as the inducing crystal seed and the precipitate,and the influence of the impeller,stirring intensity and settling time on prilling were studied with the strontium concentration of 5 mg/L in raw water.The results showed that improving the size of impeller and increasing the stirring intensity were beneficial to prilling.Adjusting the settling time from 45 min to 15 min on a higher stirring intensity(416⁵59 s^-1)could also improve the prilling.The determination factor?DF?reached 130¹36 and larger crystal particles were got.During the test of strontium removal,the declining of water temperature would cause the lower removals of strontium and the membrane fouling.When the strontium concentration in the raw water was 5 mg/L,the water temperature ranged from 14¹5oC to 7⁸oC,the mean decontamination factor was reduced from 33 to 20.The amount of treated water was 46.20 m³ and 23.10 m³,and the fouling rate was30.16×10^-3?h·m?^-1and 59.03×10^-3?h·m?^-1,respectively.During the test of strontium removal,the tests were carried out when the stirring intensity was respectively 556 s^-11 and 416 s^-1,and the water temperature was respectively 21²4oC and 24²7oC.The mean decontamination factor was 170 and146,and the fouling rate was 6.76×10^-3?h·m?^-11 and 4.24×10^-3?h·m?^-1,respectively.The concentration factors of the sludge in the four tests were all higher than2×10³.The volumes of precipitate were far smaller than the conventional precipitation,which were beneficial to the subsequent treatment and disposal of the precipitate.The experimental results showed that the hybrid process had a better effect of strontium removal and operation stability.It can be used to remove the strontium from drinking water in the emergency of radioactive pollution.