潜流人工湿地对污水厂尾水中有机物去除效果

Removal efficiency of organic substances in effluent from a municipal sewage plant by a subsurface constructed wetland

摘要:

采用凝胶过滤色谱（GFC）和三维荧光光谱（EEM）分析技术，研究了两种基质水平潜流人工湿地对城镇污水处理厂尾水中有机物的去除特征。结果表明，尾水经过人工湿地系统处理后，水中溶解有机物（DOM）重均分子量（Mw）均有明显降低，其中分子量>50 千道尔顿（kDa）大分子有机物质量百分数平均下降了33.5%，而低于50 kDa的有机污染物质量百分数有所增加。三维荧光扫描显示，进水中表征出四类溶解性有机物，即色氨酸类芳香族蛋白质、溶解性微生物代谢产物、可见类富里酸、紫外类富里酸物质，经过人工湿地净化处理后相对荧光强度均有不同程度的降低；人工湿地对化学性质较为稳定、难以分解、不易被生物利用的类腐殖质有较好的去除效果，湿地出水中腐殖质芳香性较弱，含有的苯环结构有机物减少。沸石潜流湿地有机物基本上是在前1/4段就完成了大分子向低碳小分子的转化，Mw从进水的343.2 kDa下降为283.8 kDa；陶粒基质湿地是在前1/2段才基本完成。陶粒基质湿地水平潜流人工湿地对有机污染物向低碳小分子转化更为彻底，对污水处理厂尾水重有机污染物的去除效果更好。

Abstract:

Removal process and efficiency of organic substances in effluent from a municipal sewage plant were investigated and compared in a horizontal subsurface constructed wetland with different substrates by application of gel filtration chromatography (GFC) and three-Dimensional Excitation Emission Matrix Fluorescence Spectroscopy (3D-EEM). The results show that weight average molecular weight (Mw) of dissolved organic matter (DOM) in the outflow of the constructed wetland was significantly decreased, as compared to the inflow. After sewage plant effluent was treated by the subsurface wetlands, the percentage of the larger molecules > 50 kDa declined by 33.5%, while the percentage of the smaller molecules below 50 kDa showed a significant increase. Four different types of peaks such as aromatic protein-like compounds, soluble microbial byproducts, fulvic acid-like compounds, visible fulviclike and UV fulvic-like compounds in DOM from the infow significantly decreased in the effluent during purification by the subsurface constructed wetland. Especially, the biorefractory humic-like compounds can be effectively removed by the subsurface constructed wetland. Aromatic structures of humic-like compounds were weakened and organic compounds with benzene rings were decreased in the outflow of the subsurface constructed wetland. By comparison, organic matter transformations from larger molecular weight to smaller molecular weight were completed in the 1/4 front of the constructed wetland filled with ceramisites, while for the constructed wetland with zeolite substrate, the transformations were completed after the middle of the wetland bed. As compared to zeolite substrate constructed wetland system, ceramisite wetland was more effective to transform the organic matter from larger molecular weight to smaller molecular weight and remove the organic substances from the sewage plant effluent.