Experimental Study On Ultrasonic Deep De-uranization Process For Uranium-containing Wastewater

Containing the radioactive element uranium, the tail dam wastewater produced in nuclear industry deals radioactive damage to living organisms. And it will cause serious consequences if any of its emissions are admitted into the environment. With the rapid development of global nuclear industries and the wide use of nuclear fuel cycle, a growing number and variety of radioactive wastewater are produced, thus it has been a problem to be solved for lots of countries to exert strict control over the environment pollution caused by radioactive substances.In this paper, both of the conventional and ultrasonic reduction methods with zero-valence iron powders were employed for uranium removal by using the tail dam wastewater produced in a factory as raw materials. The response surface method was used to optimize the conventional reduction process at first, and Series of experimental works were systematically studied, which contained the pH value, reaction time, still time and iron dosage on the influence of the uranium removal ratio of uranium-contained wastewater. The best parameters of conventional reduction:pH value of 3, reaction time of 75min, holding time of 20min and the addition of iron powder of 0.8g(the volume of tail dam wastewater is 200mL), the rate of uranium removal reached 99.53%. the result showed that after treatment, the mixture water could meet the national emission standard.As the ultrasonic wave has the characteristics of mechanical function and ultrasonic cavitation and thermal effect, the zero-valence iron reduction method strengthened by ultrasonic wave was employed for uranium removal by using the tail dam wastewater produced in a factory as raw materials. The response surface method was also used to optimize the conventional reduction process, and series of experimental works were systematically studied, which contained the pH value, reaction time, still time and iron dosage on the influence of the uranium removal ratio of uranium-contained wastewater. The best parameters of conventional reduction:pH value of 3, reaction time of 60min, holding time of Omin and the addition of iron powder of 0.2g (the volume of tail dam wastewater is 200mL), the rate of uranium removal reached 99.23%, the result showed that after treatment, the mixture water could meet the national emission standard.After the analysis of variance (ANOVA) for further, judgment on the accuracy of the model, the regression equation of pH value, reaction time, iron dosage and uranium-removal rate was obtained. And from which it could be found that the model predicted values had a little error to the measured values, the result of calculation is very precise and reliable, so the selected model would be very helpful to the experiment. In addition, using the method strengthened by ultrasonic wave, the reaction time could be shortened by 20% while the iron dosage could be reduced by 75%, and without the holding process under the optimum conditions, thus the reaction time was shortened greatly, it must have an obvious advantage and a promising prospect definitely.