【作者】 刘大鹏；

【导师】 王继徽；

【作者基本信息】 湖南大学 ， 环境工程， 2004， 硕士

【摘要】 氨氮（NH₃-N）是水相环境中氮的主要存在形态，是导致水体富营养化的重要污染物质，随着全球水环境不断恶化及公众环保意识日益增强，各国都纷纷制定了严格的氨氮排放标准，因此，探索经济有效的氨氮废水处理技术已成为当前水处理领域的热点和难点。 在人们继续致力于废水生物脱氮工艺深入研究的同时，化学沉淀脱氮技术的发展因其工艺简单、反应迅速、净化率高、尤其适用于高浓度氨氮废水的优势正方兴未艾。本文以某硬质合金厂高浓度氨氮废水为对象，研究了采用化学沉淀法，向废水中投加沉淀剂，在一定条件下与氨氮发生反应，形成难溶性磷酸铵镁（MgNH₄PO₄·6H₂O）沉淀的脱氮过程。 在大量实验基础上，对反应的动力学参数进行研究，探讨了反应温度、pH值等对氨氮去除的影响。结合反应的动力学特性，以MgHPO₄·3H₂O为沉淀剂对废水进行脱氮，控制反应pH值在8.5～10的范围，废水中的氨氮可由850 mg／L降低到50 mg／L以下（去除率超过96％），而余磷含量低于20 mg／L，为后续生化处理的顺利进行提供了保证。同时，生成的磷酸铵镁晶体不仅纯度高、结构紧密具有良好的沉降性能，易于工程中的分离提取，而且对废水中的有毒、有害物质基本无吸附，适于回收利用，使污染物的资源化成为可能。 为了获得最佳的反应条件，文章还尝试应用神经网络方法对正交实验结果进行优化，克服了基于传统的正交分析和回归分析选取较优水平进行实验条件优化的结果往往与实际情况不符，有时优化结果还不如原来正交试验中的某一次试验的不足，并且实现了对反应后氨氮和余磷浓度的双目标优化、控制，为今后的研究提供了解决问题的新思路和方法。 实验研究结果要与实际应用相结合，本文还探索了一套自行研究开发的氨氮废水处理工艺流程，为化学沉淀法脱氮在工程中应用起到了一定的指导作用。更多还原

【Abstract】 Nitrogen in water environment exists mainly in the form of ammonia-nitrogen, which is the principal contaminant causing eutrophication of water body. With continual worsening of water quality and enhancing of public environmental protection consciousness many countries have constituted strict ammonia-nitrogen discharge standards, therefore, it has already become the focus and difficulty in the present wastewater treatment field to explore the economy and effective treatment technology for ammonia-nitrogen wastewater.Having the advantages of simple technology, high reaction speed, high removal efficiency, especially being suitable for the high concentration ammonia-nitrogen wastewater, chemical precipitation method for ammonia-nitrogen removal is blossoming while people are endeavoring in the further research on removing ammonia-nitrogen by biochemical process. In this paper, the process for ammonia-nitrogen removal was studied by adding some chemicals into the wastewater of a certain hard alloy plant to produce the struvite(MgNH4PO4 6H2O) precipitate.Ammonia-nitrogen in wastewater was removed by using magnesium hydrogen phosphate(MgHPO4 3H2O) as precipitant. Based on a large amount of experiments, the kinetic parameters about ammonia-nitrogen removal as struvite were studied, especially the effect of temperature and pH value etc. According to the kinetic characteristics, the ammonia-nitrogen concentration of the wastewater is reduced from 850 mg/L to 20 mg/L(removal efficiency is over 96 % ) while residual phosphorus content is under 20 mg/L controlling the pH in the range of 8.5 ~ 10. In addition, the struvite precipitate formed have not only compact crystal structure which shows good sedimentation capability, but also high purity without adsorption of toxic and harmful substances in wastewater, which ensures the possibility of struvite reutilization.In this paper, a new method based on neural network was used for optimizing orthogonal trial results to obtain the best reaction conditions. This method overcomes the shortcoming that the optimal results are always not in accordant to the truth, being sometimes not so good as that of a certain experiment by means of orthogonal analysis and regressive analysis. Furthermore, the purpose of double object optimization on the residual ammonia-nitrogen and phosphorus content isachieved. In a word, this new method provides a new way for the further research.In addition, a set of process flow was developed by author for ammonia-nitrogen removal from wastewater with struvite precipitation method, which can be used in practice.更多还原