Research On Treatment Of Simulated Radioactive Wastewater Containing Cobalt And Strontium

With the widespread use of nuclear energy in various fields,radioactive pollution has attracted many countries'attentions,and the study on radioactive pollution is imminent.⁶⁰Co(T_1/2=5.27 a)derives from corrosion products activated by neutrons in cooling system.⁹⁰Sr(T_1/2=28.6 a)is the main fission product of ²³⁵U and ²³⁹Pu.Considering the threat form radioactive wastewater to human health and environment,special attentions should be paid to treatment of radioactive pollution from nuclear accident.The removal of strontium through pellet coprecipitation followed by sand filtration was stable,and filtration rate had little impact on DF?Detamination Factor?of strontium.At the rate of 8.5 m/h,10.5 m/h and 12.5 m/h,the DFs of strontium were346?329 and 305,respectivley.Compared to the lower filtration layer,the upper filtration layer with the smaller particles was more possible to be blocked.Improving filtration rate enhanced the adherence and interception of SS by upper filtration layer,and helped reduce the pollution in the lower filtration layer.The cobalt was removed through pellet coprecipitation-microfiltration,and the jar test indicated that the mean DF attained 1638.The removal of cobalt by pellet coprecipitation-microfiltration was related to the formation of Co?OH?₂ precipitates produced by Co²⁺and OH^-(hydrolysis of CO₃^2-)firstly,then Co?OH?₂ precipitates adhered to the surface of CaCO₃ so that they could sank together,and finally the smaller pellets were removed by membrane separation.Compared to the traditional chemical precipitation,pellet coprecipitation could evidently enhance the removal efficiency of cobalt,and the mean DF increased from 2.57 to 74.24 due to the formation CaCO₃ cystal seed.The content of Ca²⁺played a significant role in pellet and cobalt removal,and improving Ca²⁺dosage helped form larger Ca CO₃ crystal seed,which provided more attachment areas and finally increased DF of cobalt.