Removal of radioactive iodine and cesium in water purification processes after an explosion at a nuclear power plant due to the Great East Japan Earthquake

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• 作者：Koji Kosaka ; Mari Asami ; Naoya Kobashigawa ; Keiko Ohkubo ; Hiroshi Terada ; Naohiro Kishida ; Michihiro Akiba
• 关键词：Radioactive iodine ; Radioactive cesium ; Powdered activated carbon ; Chlorination ; Coagulation ; Water purification process
• 刊名：Water Research
• 出版年：2012
• 出版时间：15 September, 2012
• 年：2012
• 卷：46
• 期：14
• 页码：4397-4404
• 全文大小：366 K

文摘

The presence of radionuclides at five water purification plants was investigated after an explosion at a nuclear power plant hit by the Great East Japan Earthquake on 11 March 2011. Radioactive iodine (¹³¹I) and cesium (¹³⁴Cs and ¹³⁷Cs) were detected in raw water in Fukushima and neighboring prefectures. ¹³¹I was not removed by coagulation-flocculation-sedimentation. ¹³¹I was removed by granular activated carbon (GAC) and powdered activated carbon (PAC) at a level of about 30 % -40 % , although ¹³¹I was not removed in some cases. This was also confirmed by laboratory-scale experiments using PAC. The removal percentages of ¹³¹I in river and pond waters by 25?mg dry/L of PAC increased from 36 % to 59 % and from 41 % to 48 % , respectively, with chlorine dosing before PAC. ¹³⁴Cs and ¹³⁷Cs were effectively removed by coagulation at both a water purification plant and in laboratory-scale experiments when turbidity was relatively high. In contrast, ¹³⁴Cs and ¹³⁷Cs in pond water with low turbidity were not removed by coagulation. This was because ¹³⁴Cs and ¹³⁷Cs in river water were present mainly in particulate form, while in pond water they were present mainly as cesium ions (¹³⁴Cs⁺ and ¹³⁷Cs⁺). However, the removal of ¹³⁴Cs and ¹³⁷Cs in pond water by coagulation increased markedly when ¹³⁴Cs and ¹³⁷Cs were mixed with sediment 24?h before coagulation.