电镀废水中典型污染物的资源化处理与过程机制研究
文献类型：学位论文
| 作者 | 关伟 |
| 学位类别 | 博士后 |
| 答辩日期 | 2016-12 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 赵旭 |
| 关键词 | 电镀废水 镍铵络合物 镍铵络合物 Electroplating wastewater, Nickel ammonia complex, Fluoride, Hypophosphite, Resource 氟化物次磷 |
| 其他题名 | 电镀废水； 镍铵络合物 镍铵络合物 ； 氟化物次磷 |
| 学位专业 | 环境工程 |
| 中文摘要 | 近年来，我国电镀行业发展迅速，据不完全统计，我国电镀厂约 2万家，每年排出的电镀废水量约 4.0亿立方。电镀废水中含有大量高浓度的重金属、磷酸盐、氨氮、氟化物等典型污染物。传统的电镀废水处理方法仅限于对污染物的去除，而忽视了对污染物的资源化循环利用。探索经济有效的电镀废水处理方法以解决资源短缺与污染物处理方式的矛盾，在有效控制污染物达标排放的同时实现污染物的资源化回收，对于排污企业可持续发展、资源循环利用、保护和改善环境具有重要现实意义。 针对从实际电镀含镍废水中回收镍和去除氨氮，分别进行了小试试验和中试运行。根据中试运行结果，提出了镍回收过程及氨氮去除途径。在反应前 90min，主要进行镍铵络合物的破络合及镍在阴极的沉积，镍铵络合物被阳极氧化破络合游离出 NH4＋ ，NH4＋ 被进一步氧化降解。在中试运行过程中，电化学反应器表现 出较为稳定的运行效果，连续运行 15 次之后，镍的回收效率保持在 75~95％，氨氮的去除效率维持在 25~35%。 考察了电芬顿系统对次磷酸盐氧化及回收效率的影响与作用机制。研究表明，电流强度较小时，Fe2+的溶出量较少，电芬顿反应不充分，导致对次磷酸盐的氧化效果不佳，大量的次磷酸盐残留在溶液中。随着电流强度的增加，各价态的磷酸盐浓度均有所降低。电芬顿系统在酸性条件下对次磷酸盐的氧化性能较好。当pH 过低时，亚磷酸盐难以被氧化为正磷酸盐，导致总磷的回收率较低。当 pH较高时，由于羟基自由基的产生效率较低，次磷酸盐难以被有效氧化。磷回收产物的主要物相为磷酸铁，羟基自由基对次 /亚磷酸盐的氧化效果明显，此外，次磷酸盐到正磷酸盐的氧化过程是回收磷酸铁的控制步骤。 通过电氧化协同电絮凝协同处理了实际电镀污水处理厂的氟化物和氨氮废水。对污水处理厂含氟化物及氨氮废水的水质成分进行了分析，该废水的水质波动性较大，水质成分复杂，且多种干扰离子共存，废水中氨氮及氟化物的浓度较高。通过小试试验，分别考察了 pH值和电流强度对氟化物去除率的影响，同时考察了 pH值和 NaClO投加量对氨氮去除效率的影响。根据小试实验，电絮凝去除氟化物的最佳 pH 值为 6.0，电流强度为 0.8A，折点加氯除氨氮的最佳 pH 值为 10.0，NaClO的最佳投加量为 2‰。在小试实验基础上进行了中试运行，系统连续运行 30 次，出水中氟化物的浓度范围在 7.5~9.5 mg/L，氨氮的浓度范围在9.5~12.5 mg/L.采用化学法协同电化学法进行分阶段分别处理氟化物和氨氮，系统运行费用较低，且运行效果稳定。出水水质能够达到《电镀污染物排放标准》(GB21900-2008)中的表 2标准，即：氨氮浓度＜15mg/L；氟化物浓度＜10mg/L. 基于水化硅酸钙的表面羟基和缓释 Ca2+与 OH-的特性，将其用于从含氟废水中回收氟化物。相对于 CaCl2, CaO以及雪硅钙石等其他含钙材料而言，水化硅酸钙表现出较好的氟回收性能。整个氟回收过程在 pH为 6.4~7.4 的范围内自发进行，无需额外添加化学药剂调节 pH。水化硅酸钙中大量的 Ca-OH链，能够与F-发生离子交换，最终形成 CaF2。水化硅酸钙在氟回收方面具有较好的应用前景。 |
| 英文摘要 | In recent years, the electroplating industry developed rapidly. In China, there are about twenty thousand electroplating enterprises, and the electroplating wastewater reached to 400 million tons per year. There are a large number of high concentrations pollutants such as metal ions, phosphate ion, ammonia nitrogen, and fluoride in the wastewater. The traditional treatment of electroplating wastewater is aim at the removal of the pollutants, but ignores the recycling use of these pollutants. Thus, it is important to explore the cost－effective methods to alleviate the resource shortage problem. This is significant for the sustainable development of the electroplating company, and recycling of resources, and protects the environment. Aim at the removal of nickel ions and ammonia nitrogen from the practical electroplating wastewater, a series of bench－scale experiments and pilot-scale experiments were performed. The reaction processes at the anode and cathode were explored. The nickel ammonia complexes were destructed by the electro-oxidation process in the initial 90 min, and Ni2+ ions were deposited on cathode at the same time. Then, the free NH4+ generated from the decompelxation of ammonium citrate was further oxidized by a competitive electro－oxidation process. At a pilot scale, the electrochemical reactor exhibiting at steady capacity for ammonia nitrogen removal rate of 25 - 35% and nickel recovery rate of 75 - 95%, respectively. Hypophosphite was removed by electro-fenton methods, and the effect of removal rate was investigated. According to the results, the release rate of Fe2+ is low when the current density is poor, and this leads to the electro-fenton insufficiency. As a result, hypophosphite cannot be oxidized to phosphate. In addition, when the pH is too low, hypophosphite is hard to be oxidized to phosphate. When the pH is too high, the production rate of hydroxyl radical is low, and hypophosphite is also hard to be oxidized to phosphate. The main phase of recovered products is ferric phosphate, and the oxidation effect of hydroxyl radical on hypophosphite is obvious. The oxidation from hypophosphite to phosphate is the control procedure of ferric phosphate recovery. In recent years, the electroplating industry developed rapidly. In China, there are The fluoride and ammonia nitrogen was removed by electrooxidation coordination with electroflocculation method. At first, the content of the wastewater was determined. The results indicated that the content of the wastewater was complex and various interfering ions coexisted, and the concentration of fluoride and ammonia nitrogen was high. According to the bench-scale experiments, the concentration of fluoride and ammonia nitrogen can be decreased under the discharging standard. Furthermore, according to the pilot-scale experiment, the concentration of fluoride and ammonia nitrogen was 7.5~9.5 mg/L and 9.5~12.5 mg/L, respectively during the 30 times continuous operation. The feasibility was analyzed. Based on the characteristic of the wastewater, electrooxidation coordination with electroflocculation method was proposed. The operating cost of this method is low,and the effect is stable. The concentration of fluoride and ammonia nitrogen can reach to the standard. P-CSH had a high fluorine recovery potential compared with CaCl2, CaO and C-CSH. Fluorine recovery process continued spontaneously at pH values of 6.4~7.4 by P-CSH without extra adjustment. The fast Ca2+ dissolution rate was also likely to favor fluorine precipitation with free Ca2+. The presence of massive Ca-OH groups in P-CSH enhances the fluorine recovery capacity by forming insoluble CaF2. The as-prepared P-CSH exhibited the potential for fluoride recovery and recycling. |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/36797]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 关伟. 电镀废水中典型污染物的资源化处理与过程机制研究[D]. 北京. 中国科学院研究生院. 2016. |
入库方式： OAI收割
来源：生态环境研究中心
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