| Summary: | 碩士 === 國立中正大學 === 應用地球物理研究所 === 104 === People have recognized that the human activities lead to the degradation of the environment, and constructed wetland is one of the well-known technologies for wastewater treatment. Constructed wetland is a water treatment system which can remove the contaminants in water by using physical, biological and chemical mechanisms. It can achieve greater efficiency and energy-savings at lower costs; therefore, constructed wetlands become the major predominate technology for wastewater treatment. In this study, multiple chemical components were measured and were subsequently analyzed with multivariate analysis method for depicting the major chemical reactions in the studied constructed wetland.
The studied constructed wetland is located in Taoyuan County, north Taiwan. It’s a horizontal surface flow constructed wetland composed of ten cells. The water in wetland was pumped from Nankan River, which is recharged by wastewater from Hwaya Technology Park and Industrial Zones of Linkou, Guishan and Nankan. The water of inflow and outflow from each cell were collected for the measurements of inorganic components with ICP-MS, IC and spectrophotometer. The hydrochemical results show that water quality had dramatically changed at the 3rd cells and gradually became stable in the following seven cells.
The PCA results demonstrate that two major factors can be extracted from the hydrochemical result of shallow water analysis, which can respectively explain 52.09% (PC1) and 30.05% (PC2) of the total variance of water hydrochemical data. PC1 is characterized by high loadings of Al, conductivity, and most of trace heavy metals. It can be derived that PC1 is dominated by aluminum hydrate co-precipitation and adsorption. On the other hand, in the plot of PC1 vs PC2, the hydrochemistry of water mainly evolve along PC2 axis. PC2 is composed of Fe, Mn, NH4+, dissolved oxygen, pH with high loadings. These chemical components are predominately controlled by redox reactions.
In addition, it is obvious that there is a large jump along PC2 in the 3rd cell. It is derived that there was a considerable amount of reducing substances recharging into the 3rd cell. After that, the reducing substances were gradually oxidized and were finally reduced to a very low level in 8th cell. Based on the results of all samples PCA and the rare earth elements, the reducing substances in 3rd cell may derive from the bottom sediments in the 3rd cell.
Keywords: Constructed wetland; Multicomponent Hydrochemical Analysis; Principle component analysis; Cluster analysis
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