城镇污水厂尾水人工湿地深度处理过程中DOM三维荧光光谱特征

采用三维荧光光谱(3D-EEM)分析研究了两种基质水平潜流人工湿地在深度处理城镇污水处理厂尾水过程中溶解有机物(DOM)组成特征。结果表明,两种潜流人工湿地对尾水中CODcr和DOC的去除率平均分别达到61.6%和70.1%。相比较而言,陶粒基质湿地对尾水有机物去除效果略优于沸石基质湿地。三维荧光扫描结果显示,湿地进水中表征出类溶解性有机物,即色氨酸类芳香族蛋白质(S)、溶解性微生物代谢产物(T)、可见类富里酸(M)、紫外类富里酸物质(A)。经过人工湿地净化处理后,出水中4个峰的相对荧光强度均有不同程度的降低,其中M峰和T峰的相对荧光强度降低最为明显,平均分别降低了16.4%和11.7%;人工湿地出水中腐殖类物质芳香性较弱,含有的苯环结构有机物较少,这说明潜流人工湿地对尾水中化学性质较为稳定、难以分解、不易被生物利用的类腐殖质有较好的去除效果。M峰和T峰的荧光强度在沿程上逐渐减小,S峰随沿程呈现出先增大后减小的趋势。与沸石湿地相比较,陶粒基质水平潜流人工湿地系统对尾水中DOM的特征峰荧光强度削减更为明显。

Excitation-emission matrix fluorescence spectra characteristics of DOM in a subsurface constructed wetland for advanced treatment of municipal sewage plant effluent

Composition and dynamics of dissolved organic matter (DOM) were analyzed in a horizontal subsurface constructed wetland for advanced treatment of municipal sewage plant effluent using three-dimensional excitation emission matrix fluores cence spectroscopy (3D-EEM). The results indicate that the two subsurface constructed wetlands performed excellent purification of organic substances, and the removal rates of COD(cr), and DOC were 61.6% and 70.1%, respectively. The constructed wetland system filled with ceramsite showed slightly greater removal efficiency of organic substance than that with zeolite substrate. Four different types of peaks such as aromatic protein-like compounds (S), soluble microbial byproducts (T), fulvic acid-like compounds, visible fulvic-like (M) and UV fulvic-like compounds (A) were found in DOM from inflow and outflow of the subsurface wetlands based on the three-dimensional fluorescence spectroscopy analysis. The fluorescence intensity of the four peaks was significantly decreased in the effluent after purification by the subsurface constructed wetlands. Especially, the visible fulvic-like compounds and soluble microbial byproducts were effectively removed from the sewage plant effluent by the subsurface constructed wetland with fluorescence intensity reduction percentages of 16.4% and 11.7%. Aromatic structures of humic-like compounds were weakened and organic compounds with benzene rings were decreased in the outflow of the subsurface constructed wetland. This indicates that the subsurface constructed wetlands can decompose the chemically stable and biorefractory humic-like compounds. The fluorescence intensity of M and T peaks decreased along distance, while the fluorescence intensity of S peaks firstly increased, then decreased along the distance of the subsurface constructed wetlands. As compared to zeolite substrate constructed wetland system, the constructed wetland system filled with ceramsite was more effective to reduce the fluorescence intensity of characterized peaks of DOM from the sewage plant effluent.