Water Quality Assessment for Wastewater Reclamation Using Principal Component Analysis

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 NH3-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.

Keywords: principal component analysis, reclaimed water, wastewater reclamation, water quality assessment