真空膜蒸馏技术的工艺条件优化及其在深度净化低放含铀废液中的应用

Experimental Research of Vacuum Membrane Distillation Technology for Deep Purification of Low-level Uranium-containing Wastewater

采用聚四氟乙烯(PTFE)中空纤维膜组件开展了真空式膜蒸馏(VMD)处理模拟及真实低放含铀废液试验。对膜组件运行参数进行了优化,考察了料液温度、流速及真空度对膜通量和截留效果的影响,并探讨了VMD过程中的温差极化效果,同时研究了VMD处理核燃料元件生产工艺低放含铀废液的可行性。结果表明:实验室工况条件下,温度为75℃,流速0.30m/s,真空度为-0.090MPa为较佳的工艺条件,此时膜通量为2.2L·m^-2·h^-1;针对模拟和真实废液,铀的截留率始终大于99.99%,剩余浓度小于1μg/L,出水铀浓度可一次性满足国家排放标准(GB 23727—2009)。说明VMD对于核燃料元件生产过程中产生的复杂体系低放废液具有高效的净化效果,可供核工业低放废液的深度净化参考。

Polytetrafluoroethylene(PTFE)hollow fiber membrane module was used for vacuum membrane distillation(VMD)treatment simulation and real low-level uranium-containing wastewater.Firstly,the operating parameters of the membrane module were optimized,and the effects of feed temperature,velocity and vacuum degree on the flux and rejection of the uranium were investigated.The effect of temperature difference polarization in the VMD process was discussed.Then,the production of nuclear fuel elements by VMD processing was studied.Subsequently,the feasibility of VMD for the treatment of low-level uranium-containing wastewater in the production process of nuclear fuel elements was studied.The results show that at a temperature of 75℃,a velocity of 0.30 m/s,and a vacuum of-0.090 MPa under the laboratory conditions,the permeate flux is 2.2 L·m^-2·h^-1.For simulated and real wastewater,the uranium rejection rate is always greater than 99.99%.The remaining concentration is less than 1μg/L,and the uranium concentration in the effluent can meet the national emission standard at one time(GB 23727—2009).Such results suggest that VMD has a high-efficiency purification effect on the low-level wastewater in the complex system produced during the production of nuclear fuel elements,and can provide new ideas and data references for the deep purification of low-level wastewater in the nuclear industry.