人工湿地填料改良在珠江源头地区水环境保护中尾水深度除磷的可行性研究

MODIFICATION OF CONSTRUCTED WETLAND FOR POLISHING OF WASTEWATER TREATMENT DISCHARGE IN THE HEADWATER REGION OF THE PEARL RIVER

康瑞鹏

11649177

硕士

环境工程

郑焰

2018-05-28

2018-07-09

哈尔滨工业大学

深圳

21 世纪以来，全球化和国际化进程促使贵州建设双龙航空港经济区，是中国西部参与世界高层次分工的重要举措。经济区地处中国西南云贵高原东部、贵阳市与黔南州龙里县交界处，地貌类型为典型的喀斯特地貌。经济区位于鱼梁河上游，在贵阳市重要水源汪家大井准保护区范围内，同时为珠江流域水源地，水环境保护要求极高，新区规划中提出：不增加污染排放，不影响水源水质。然而，现有污水处理厂工艺无法满足其排放水质需求，尤其是氮磷指标，因此需要寻求经济环保的解决办法，使排放水质达到《地表水环境质量标准》（GB3838-2002）中的地表水III 类水体标准。本论文提出通过人工湿地对污水厂一级A 标准出水尾水进行深度处理，以实现出水水质满足地表水III 类水体标准的目标。人工湿地是国内外均有应用的污水处理系统，能够经济有效地净化污水，运行费用低廉，然而作为山地水源地保护区的污水深度处理单元，占地面积必须缩小到现有人工湿地技术的至少十倍，才可进行应用，因此亟需提升其处理效率。为了提升人工湿地处理效率, 本论文拟通过合成磁铁矿颗粒以湿地填料基质进行改良，分析合成制备磁铁矿颗粒的吸附特性，并针对污水中磷（P）指标，构建室内模拟砂砾石实验系统，评估人工湿地作为污水深度处理单元对污水处理厂一级A 标准出水的处理效果。主要结果为：1、制备的材料表征结果表明：合成的材料确实为磁铁矿颗粒，然而其颗粒粒径为0.4 微米-15 微米，属于微米级磁铁矿颗粒，并非纳米级。微米级磁铁矿颗粒仍具有较大的重量比表面积（451 m2/kg），适合作为吸附剂对湿地填料基质改良。2、微米级磁铁矿颗粒吸附实验结果表明：在25℃时，对磷的吸附容量可以达到50 mg/g；磁铁矿对磷的平衡吸附量随着温度的升高而增加，说明磁铁矿对磷的吸附是一个吸热过程，可以自发进行；在25℃时，对磷的吸附只需60分钟即可达到吸附平衡；磁铁矿对磷的吸附适合伪二级动力学模型，其对磷的吸附是一个化学吸附过程，且其吸附过程符合Langmuir 等温线吸附方程，吸附过程属于单分子层吸附；当pH 为2 到6 之间时，其对磷的吸附效果好, 随pH 升高，吸附明显下降。3、室内砂砾石实验系统研究表明：含磁铁矿颗粒的填料基质对磷的去除率可以达到90%以上，而普通砂砾石基质填料对磷的去除率仅有60%左右，经过连续180 h 的连续进水后，砾石基质填料系统对磷的去除率接近0%，而含磁铁矿的砂砾系统对磷的去除率仍保持在40%以上；含磁铁矿的系统对高浓度(1mg/L to 25 mg/L)磷溶液也具有较高的去除率，可达到87%以上，因此推断改性填料基质对缩小湿地占地面积将具有一定效果。论文结论为颗粒磁铁矿有望作为新材料对湿地填料基质改良，可以在提升尾水处理效率的同时减少湿地面积。

The development of Shuanglong Airport Economic Zone was initiated in 2015 as an important measure for China’s western region to participate in and climb the world’s economic ladder. The economic zone is located mostly in Guiyang City, and includes a part of adjacent Longli County. Here, karst landform dominates. The economic zone is located in a water sensitive environment. Not only it is located up gradient of a supply well for Guiyang City, Wangjiadaling, the upper reaches of the Yuliang River is also part of the numerous first order streams that consisted of the head water for the Pearl River Basin. Thus, environmental protection requirements are stringent in order to protect this sensitive region. The planning documents of the Shuanglong called for no increase in pollutant discharge and no measurable effect on water quality. At present, the wastewater treatment plant cannot meet such requirements, especially the N and P indicators. Therefore, economical and environmentally friendly solutions to improve waste water treatment so that th e it meets Class III water standards for surface waters specified in the Environmental Quality Standards (GB3838-2002) are desirable.Waste water polishing through constructed wetland holds the potential to improve the effluent water quality to meet Class III water standard of surface water. Constructed wetland has been widely used abroad and is gaining popularity in China. One of the main advantages is the low operational cost. One of the drawbacks of constructed wetland is the requirement of large land areas for construction. In a mountainous water source protection area such as Shuanglong with limited availability of land suitable for wetland construction, the area used for construction should be made at least ten times less than that of the existing co nstructed wetland. To reach this goal, this thesis investigates whether modification of the media used in constructed wetland can result in better treatment efficiency, eventually allowing for a reduction in the land requirement.This thesis proposes to modify the wetland media through magnetite particles, either synthesized or formed in situ, to improve waste water polishing efficiency. As the first step, the adsorption properties of synthetic magnetite particles were investigated, and the P removal efficiency was evaluated in a sand and gravel experimental system constructed in the laboratory. The key findings are:1. Synthetic material is confirmed to be magnetite particles through X-Ray Diffraction analysis. However, the particle size of the synthetic mate rial ranged from 0.4 μm to 15 μm, which belongs to micron-sized magnetite particles and is not nano-sized. The micron-sized magnetite particles still have a large specific surface area of 451 m2/kg.2. Adsorption of phosphate by synthetic magnetite is a chemical adsorption process. Conceptually, it follows the Langmuir isotherm thus possibly through a monolayer adsorption reaction. Adsorption capacity for phosphate by synthetic micron magnetite particles at 25°C can reach 50 mg/g; it increases with increasing temperature. Phosphate adsorption is thus an endothermic process, with increasing temperature favoring the reaction. At 25°C, the adsorption of phosphate takes about 60 minutes to reach adsorption eq uilibrium. A Pseudosecond- order kinetics model fits the experimental data well. Between pH 2 and 6, the adsorption rate is high. However, with increasing pH (pH>6), it decreases rapidly.3. Lab-scale sand and gravel experimental system studies have shown that the removal efficiency of phosphate from the media containing magnetite particles can be as high as 90%. In comparison, the removal efficiency of phosphate by the sand and gravel only media was only about 60%. After 180 h, the removal efficiency of phosphates from sand and gravel only media is close to 0%, while the it is still at 40% for the same media modified with magnetite. The system containing magnetite also has a high removal rate (>87%) for solution containing high levels (1 mg/L to 25 mg/L of phpsphate).In conclusion, magnetite particles holds potential as a material to modify the media of constructed wetland to improve removal efficiency of phosphate in effluent discharged from waste water treatment facilities in order to reduce the area of constructed wetland.

磁铁矿颗粒 磷 人工湿地 污水深度处理

magnetite phosphate constructed wetland nature-based solutions ecological engineering

中文

联合培养

哈尔滨工业大学

康瑞鹏. 人工湿地填料改良在珠江源头地区水环境保护中尾水深度除磷的可行性研究[D]. 深圳. 哈尔滨工业大学,2018.