ABSTRACT. The water quality assessment for wastewater reclamation is usually related to many parameters. This would introduce difficulty in objectively and comprehensively evaluating the overall water quality, and affect the water reuse safety. To address this problem, a principal component analysis (PCA) method was employed in this study to identify the components that mainly affect water quality. By examining eleven indices, a large amount of water quality data of four typical wastewater reclamation treatment plants (WRTP) in northern China were collected. The PCA results indicated that four uncorrelated principal components (PC) could represent the majority of water quality information. The first PC was mainly involved with the COD index and the sensory properties of water, including chroma, turbidity, dissolved solids, and total hardness. The second PC included the indices of NH 3 -N, DBP (di-n-butyl phthalate), and DEHP (Di (2-ethylhexyl) phthalate), reflecting the water reuse safety on both human health and ecological environment. The total phosphorus (TP) and iron (Fe) were included in the third PC, while the fourth PC included dissolved oxygen (DO). Based on PCA analysis, a comprehensive score of water quality was also obtained for each WRTP during each representative month, and it was found that the wastewater reclamation process could greatly affect the quality of reclaimed water. These four identified principle components can help evaluate the overall water quality, and much attention should be given to their effective monitoring and control during the operation of WRTP or the selection of appropriate treatment process.

The technology core of biological removal of iron and manganese by contact oxidation is iron and manganese oxidizing bacteria. This article made a study on down flow and up flow filtration, the results show that down flow filtration of the homogenous filter medium is more adapted to the reproduction of biotic formation. Homogeneous filter increase the depth of effective biological filter and the biomass that develop the bio-chemical capability of the biological filter. Homogeneous filter increase removal capability of Fe/Mn and alleviate the formation of sludge cake, which can get a quite backwash. Down flow homogeneous biological filter can solve some engineering problems of heterogeneous up flow filtration. The down flow homogeneous biological filter is more adapted to the removal of Fe/Mn in groundwater.

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