废水化学除磷的试验、理论与应用研究

【作者】 徐丰果；

【导师】 罗建中；

【作者基本信息】 广东工业大学 ， 环境工程， 2003， 硕士

【摘要】 本文主要研究了废水化学沉淀法除磷以使废水能达标排放的试验条件，化学除磷投药量的确定以及化学除磷的作用机理，并将研究成果应用于工程实践。 首先对废水中磷的污染及除磷技术，尤其是生物除磷和化学除磷技术进行了比较，总结和展望。文章认为，磷污染是废水富营养化的关键因素，废水中总磷通过生物法处理往往不能达到排放标准，所以有必要研究废水的化学法除磷。化学法除磷关键在于药剂的选择和沉淀条件的控制，化学法除磷要和生物法除磷综合起来进行考虑。 随后对污水处理厂的二级出水进行了化学除磷药剂筛选试验和条件试验。通过对铁盐、铝盐和钙盐分别做实验，认为铝盐的除磷效果要优于铁盐，铁盐的除磷效果要优于钙盐。在此基础上，对各药剂做了搅拌时间、pH值等的条件试验，并确立了各混凝剂的最佳混凝条件：搅拌时间为15分钟左右；铝盐的最佳pH范围是6.5左右，铁盐的最佳pH范围是9～10，钙盐在pH＞10时能获得较好的处理效果。 为了了解混凝沉淀结构，对模拟含磷废水混凝后产生的沉淀物做了能谱分析，通过确定各主要元素的重量比和原子数之比而推测出沉淀物结构，为机理研究奠定基础。 为了寻找确定化学除磷药剂投加量的简单快捷的方法，通过大量实验作出了投药系数与投加量的关系图，从而可以方便的根据关系图估算出化学除磷，尤其是低磷废水的化学除磷药剂的投加量。 在以上试验的基础上，对化学除磷的作用过程机理进行了探讨，并分别分析了铁盐、铝盐和PAM的作用过程。分析结果表明，化学除磷包含以下过程：混凝剂的溶解与水解；金属离子与磷酸根离子形成不溶性磷酸盐；金属氢氧化物对磷酸盐沉淀的吸附，凝聚；助凝剂的架桥，捕罗，絮凝；沉淀物的沉降、分离。 在此基础上，我们对某工程的化学除磷进行了实际调试与研究，得到了较好的处理效果。更多还原

【Abstract】 The technical conditions of phosphorus removal by chemistry precipitation and quantity of reagent used in the experiments as well as mechanism of phosphorus removal by chemical method were studied in this paper. And the result of experiments studied in the lab was applied in a case of wastewater treatment project.At first, the paper compared, summarized and prospected the technology, especially microbial technology and chemical technology of phosphorus removal in wastewater. The paper deemed that the phosphorus pollution was a key factor of abundant nutrition in the water. But the standard of phosphorus in wastewater can’t reach the standard of discharge only by microbial method. Thus, it is necessary to study the phosphorus removal by chemical method. The main part of the study was about the reagent selection, the controlling of precipitation conditions and the combination of chemical methods with biological methods.Then we did the experiments of reagent selection and conditions of phosphorus removal by chemistry precipitation in the second effluence water. According to experiments, the paper considered that the aluminum ion was the best reagent in removing phosphorus and the iron ion followed it and then was the calcium ion. Based on this, we did experiments of conditions such as mill time and pH value of each reagent. The best precipitation conditions were: the mill time was about 15 minutes; the pH value of aluminum ion was about 6.5; the pH value of iron ion was from 9 to 10; the pH value of calcium ion was above 10.In order to find out the form of the deposition, we did an energy spectrum analysis on deposition of chemistry precipitation in the simulate wastewater which includes phosphorus. According to this experiment, we conjectured the form of the deposition and made a base of mechanism analysis.To find a simple shortcut of determining the quantity of reagent added, we did a lot of experiments and worked out a fig of relationship between the coefficient and the quantity of reagent added. It is easy to estimate the quantity of reagent to added in treating wastewater including phosphorus especially wastewater of low phosphorus standard.We probed into the mechanism of process of phosphorus removal by chemistry precipitation on the base of the experiments discussed above. Then we analyzed the process of action of aluminum ion, iron ion and PAM. According to the analysis, the process of phosphorus removal by chemistry precipitation including: process of dissolve and hydrolyze of precipitation; reaction of metal ion and phosphoric acid ion; process of phosphate adsorbed by hydrate; process of bridging, catching and flocculating of PAM; process of sedimentation and separation of phosphate.At last, we debugged and studied the dephosphorization by chemistry precipitation in a case of wastewater treatment project on the base of the study and get a satisfactory result.更多还原