【作者】 张晓敏；

【导师】 董文艺；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2010， 硕士

【摘要】 本文比较了硫酸亚铁还原法、零价铁粉还原法、铁炭微电解还原法对溴酸盐的去除效果。通过静态实验对各种方法的影响因素进行了研究,选出最优的方法,然后进行小试实验。最后,从处理效果、经济成本、技术可行性三方面对三种方法进行了分析比较。通过静态实验研究了FeSO4投加量、反应时间、pH值、DO等因素对硫酸亚铁还原去除溴酸盐的影响。结果表明:在pH为8.0~9.0,反应时间为30min时,投加20mg/L的FeSO4可以将30μg/L的溴酸盐去除60%。同时可知该反应满足假一级反应动力学方程。通过静态实验对零价铁粉的表面性质、溶解氧、pH值、BrO3-初始浓度、温度和摇床转速等因素进行研究。研究表明,对零价铁表面进行酸洗活化后去除效率显著提高;用氮气对溶液进行吹脱后可以提高去除效果;溶液的pH值在酸性条件下可促进还原反应的进行;溴酸盐浓度过高会对活性点产生竞争效应;铁粉表面附载一层金属铜可以加速BrO3-的还原去除。零价铁粉在连续与溴酸盐反应过程中会出现钝化现象,将溶液的pH值调节至酸性或加入一定量的Cl-可以使零价铁重新活化。铁炭微电解还原去除的影响因素包括:铁炭比、pH值、溶液的电导率、摇床转速和反应温度等。研究表明,Fe/C还原体系适宜的铁炭质量比为2:1~4:1;溶液中加入电解质后提高对溴酸盐的去除效果;增大摇床的转速可以强化溴酸盐与还原体系之间的传质过程;铁炭微电解在25~37℃的反应温度范围内均可保持较高的处理效率;铁炭微电解在pH值酸性条件下处理效果较好。对以上三种方法进行比较分析可知,铁炭微电解法效果最好。通过动态小柱实验对铁粉-活性炭柱和铁屑-活性炭柱对BrO3-的去除效果进行研究。模拟工程实际情况,对铁炭比和EBCT进行了优化。对于铁炭床易板结,从而对去除BrO3-产生影响,因此对于需要定期对其进行活化和反冲。在以上静态和动态实验研究的基础上,着重从去除效果、成本、实际操作的难易度、水厂不同运行条件(突发性应急事件、水厂正常运行等情况)以及铁炭床板结后的活化和维护等方面对三种方法进行分析比较。最后确定不同情况适宜采用的方法。更多还原

【Abstract】 This paper used ferrous sulfate reduction, zero-valent iron reduction and iron-carbon micro-electrolysis methods to remove bromate from drinking water. After investigated influencing factors by static experiments, optimal method was selected and used to investigate its continuous operation effects. Finally, the three methods were compared and analyzed in terms of treatment effects, economic costs and technical feasibility.The impacts of FeSO4 dosage, reaction time, pH value, DO and other factors on ferrous sulfate reducting bromate was investigated by static experiment. The results show that: when pH was 8.0-9.0, 60% of the bromate (30μg/L) can be removed after 30min reaction with 20mg/L FeSO4 addition. At the same time, we can see that the reaction was fit for the pseudo-first order reaction kinetics.The study investigated the factors such as surface properties of zero-valent iron, dissolved oxygen, pH, initial concentration of BrO3-, temperature and shaker speed by static experiments. The results show that: the removal efficiency of zero-valent iron was increased significantly after pickling to restore the activation; treating the solution by nitrogen stripping could improve the removal efficiency; low pH could promote the conducting of the reduction degradation reaction; too high bromate concentration would generate competition effects at active sites; the reduction and removal rate of BrO3- was accelerated because of the iron surface covered by a layer of metallic copper. Zero-valent iron powder would appear passive phenomenon in a continuous reaction with bromate. Adjusting the pH of solution to acidic or adding Cl- would make zero-valent iron re-activation.The main influencing factors of removal of iron-carbon micro-electro-reduction include iron-carbon ratio, pH, solution conductivity, shaker speed, reaction temperature and so on. The results show that: the suitable iron-carbon ratio in Fe/C reduction system was 2:1-4:1, add electrolytes into the solution could improve the removal rate of bromate. Increase the speed of shaking could strengthen the transfer process between bromate and reduction system. Iron-carbon micro-electrolysis could maintain a higher processing efficiency at 25-37℃. Under the low pH conditions, the treatment effect of iron-carbon micro-electrolysis was good.Comparing and analysing the above three methods, we can know that iron-carbon micro-electrolysis method is the optimal method. The paper studied the effects of BrO3- removal rate in the iron powder-activated carbon columns and iron filings-activated carbon columns through dynamic small-column tests. Simulating practical engineering, iron-carbon ratio and EBCT were optimized. The iron-carbon bed hardened easily and furthermore influenced the removal rate of BrO3-, therefore the iron-activated carbon column need to be actiated and recoiled regularly.Based on the above static and dynamic experiments study, the analysis and comparison of these three methods focused on the removal efficiency, cost, ease of practical operation, different operating conditions in water treatment plant (unexpected emergency event, normal running, etc.) as well as the activation and maintenance of iron-carbon bed board after hardened. Finally, the suitable methods for different situations were detemined.更多还原