膜法处理核电站事故情况下应急生活饮用水研究

发布时间：2018-01-07 17:12

本文关键词：膜法处理核电站事故情况下应急生活饮用水研究　出处：《上海交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：福岛事故后,核电站附近受到放射性污染的地表水带来了去除核素的问题。本文回顾了核电发展历史上的三次核事故及其对核电站附近地表水的污染。发生核事故后,地表水沾染的核素主要为131I、137Cs、134Cs等。131I为短半衰期核素,其在地表水中的活度在短期内降低很快。常规水处理技术可用来去除地表水中长寿命核素,但去除效果不佳。本文研究了纳滤膜及反渗透膜去除目标核素效果,并通过对核事故下地表水中含有的核素的特点、种类及危害程度的调研确定了将Co2+、Cs+、Sr2+作为核素处理对象。在考察膜处理影响因素的同时也介绍了纳滤、反渗透分离模型及规律,最后讨论了反渗透为核心的组合工艺去除模拟地表水中核事故释放的核素的可行性。通过实验得出以下结论:(1)实验采用平板型纳滤膜装置,考察了运行压力、进水pH、停开机时间等因素对非放射性模拟溶液中Co2+、Cs+、Sr2+等离子的截留率及电导率的影响。随着平板纳滤膜装置运行压力的增大,纳滤膜对目标核素的去除率变大;出水电导率数值也变小。但是,当压力增大至1.2MPa后,纳滤膜对核素的去除率反而降低;出水电导率数值也增大。当压力为1MPa时,纳滤膜对Co2+、Cs+、Sr2+的去除率为98.5%、95.4%、98.4%。若进水溶液为碱性,纳滤膜对Co2+、Cs+、Sr2+离子的去除率均97%。(2)实验中采用TW30-1812低压反渗透膜组件,考察了进水核素浓度、运行压力、进水pH、无机离子干扰等因素对非放射性模拟溶液中Co2+、Cs+、Sr2+等离子的截留率及出水电导率的影响。结果表明,进水核素的浓度对核素截留率的影响不大;随着进水pH值的增大,反渗透膜对核素的截留率增大,当pH9时,核素的截留率变化缓慢;进水Ca2+离子浓度变化对Cs+离子截留率的影响最大,当Ca2+离子浓度增大为250mg/L时,Cs+离子的截留率下降到77.4%。(3)利用混凝沉淀、砂滤、活性炭、反渗透膜组合工艺处理模拟地表水,能有效降低TOC、核素及电导率数值。混凝剂的最佳投加量为50mg/L;若溶液为碱性时有利于混凝效果。反渗透膜对降低TOC、核素浓度及电导率贡献最大,对Co2+、Cs+、Sr2+的去除率分别为99.8%、91.6%、99.7%。经过组合工艺的处理,水样中TOC数值从7.19mg/L降低至0.148mg/L。
[Abstract]:After the Fukushima accident. The problem of removing nuclides from surface water contaminated by radiation in the vicinity of nuclear power station is brought about. Three nuclear accidents in the history of nuclear power development and their pollution to surface water near nuclear power station are reviewed in this paper. The main nuclides contaminated by surface water were 131I 137Cs 134Cs and 131I were short half-life nuclides. Its activity in surface water decreases rapidly in the short term. Conventional water treatment technology can be used to remove long life nuclide from surface water, but the removal effect is not good. The removal effect of target nuclides by nanofiltration membrane and reverse osmosis membrane is studied in this paper. Through the investigation of the characteristics, types and harm degree of the nuclides contained in surface water under the nuclear accident, the Co2 Cs was determined. Sr2 was used as the nuclide treatment object. The model and regularity of nanofiltration and reverse osmosis separation were also introduced while investigating the influencing factors of membrane treatment. Finally, the feasibility of removing nuclides released from simulated surface water by reverse osmosis combined process is discussed. The following conclusions are drawn from the experiment: 1) the plate type nanofiltration membrane device is used in the experiment. The effects of operating pressure, influent pH and shutdown time on Co2 Cs in non-radioactive simulated solution were investigated. The effect of Sr2 plasma rejection rate and conductivity. With the increase of the operating pressure of the plate nanofiltration membrane, the removal rate of target nuclides by nanofiltration membrane becomes larger. However, when the pressure increased to 1.2 MPA, the removal rate of nuclides by nanofiltration membrane decreased. When the pressure is 1 MPA, the removal rate of Co2 Cs ~ (2 +) Sr _ 2 by nanofiltration membrane is 98.5% and 95.44% ~ 98.4% respectively. Nanofiltration membrane was used to study the influent nuclide concentration and operating pressure by using TW30-1812 low pressure reverse osmosis membrane module. The influence of influent pH, inorganic ion interference and other factors on plasma rejection rate and effluent conductivity of Co2 Cs ~ (2 +) Sr _ 2 in non-radioactive simulated solution were investigated. The concentration of influent nuclides had little effect on the rejection rate of nuclides. With the increase of pH value of influent, the rejection rate of reverse osmosis membrane increased, and when pH9, the change of rejection rate of nuclide was slow. The change of influent Ca2 ion concentration had the greatest influence on Cs ion rejection, when the concentration of Ca2 ion increased to 250 mg / L. The retention rate of Cs ions decreased to 77.4%. 3) the combination of coagulation sedimentation, sand filtration, activated carbon and reverse osmosis membrane was used to treat simulated surface water, which can effectively reduce TOC. The optimum dosage of coagulant is 50 mg / L; The reverse osmosis membrane contributes the most to the reduction of TOC, the concentration of nuclide and the conductivity, and the removal rate of Co2 Cs and Sr2 is 99.8%, respectively. The TOC value in the water sample decreased from 7.19 mg / L to 0.148 mg / L after the treatment of the combined process.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU991.2

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