Study On Cesium Removal From Simulated Radioactive Wastewater By The Carrying-Adsorption Process As Core

Fukushima nuclear leakage accident caused the wordwidely extensive research on the radioactive pollution.Among the nuclides released from this accident,¹³⁷Cs has drawn considerable attention due to its long half-life,high biological toxicity and strong mobility.Copper ferrocyanide?CuFC?is a high efficient and environmentally friendly adsorbent.When the radioactive ¹³⁷Cs and non-radioactive ¹³³Cs simultaneously existed in the solution,after adsorption and solid-liquid separation processes,the decontamination factor calculated based on activity concentration was equal to that calculated based on mass concentration.This result explicitly answered that ¹³⁷Cs and¹³³Cs possess the same decontamination property.The effects of initial cesium concentration,CuFC doseage and coexisting ions on the CuFC adsorption process was evaluated by the means of Freundlich adsorption isotherm and response surface methodology?RSM?.The adsorption isothermal surface was established to optimize the adsorbent dosage and initial cesium concentration.Based on the calculation results,it could be found that there existing an optimum initial cesium concentration,at which the highest decontamination factor could be obtained at a certain CuFC dosage.In the enginerring practice,artificially dosing ¹³³Cs to increase cesium concentration to a suitable level could significantly improve ¹³⁷Cs removal.This method was named as carrying-adsorption.When the CuFC dosage and initial cesium concentration was 0.08 g/L and 2500?g/L,respectively,the decontamination factor could achieve 1.65×10⁵.The coagulation unit was combined with adsorption-microfiltration process to develop a hybrid process of adsorption-coagulation-microfiltration for the cesium removal from the simulated radioactive wastewater.This novle process could effectivelyalleviatemembranefoulingwithoutseriouslydeteriorating decontamination performance.Therefore,the obstacle of solid-liquid separation caused by the fine particle size could be perfectly solved.A simple calculation method was established based on the Freundlich adsorption isotherm,which could accurately predict the effluent cesium concentration.When the CuFC dosage were0.025 g/L and 0.04 g/L,respectively,ignoring the influence of sludge discharge,the errors between experimental and calculated values were all below 10%.The hybrid process of adsorption-coagulation-sand filtration was developed to remove cesium from drinking water.The experimental results demonstrated that this process was high efficient and safe,and could be compatible with the existing waterworks facility.The development of this process provides technical support for large-scale engineering application to cope with radioactive cesium pollution.