Estimation of Global Water Quality in Four Municipal Wastewater Treatment Plants over Time Based on Statistical Methods

Abstract

Wastewater from urban and industrial sources can be treated and reused for crop irrigation, which can certainly help to protect aquifers from overexploitation and potential environmental risks of groundwater pollution. In fact, water reuse can also have negative effects on the environment, such as increased salinity, pollution phenomena or soil degradation, among others. Consequently, reuse of wastewater requires rigorous treatment and a very detailed analysis of different parameters, in compliance with established quality limitation standards. Therefore, this study was carried out to develop a prediction of temporal changes in water quality by introducing a wastewater quality index (WWQI) for four regional wastewater treatment plants (WWTPs) in Murcia, Southeast Spain, where a significant number of physicochemical and biological parameters are obtained in time series over the period 2019–2021. For this purpose, multivariate statistical analyses have been adopted to predict the performance of WWQI. By robust PCA of the sixteen physicochemical variables of the raw and treated wastewater, five main principal components (PCs) were extracted, which explain between 21.39% and 36.79% of the data variability. From the loadings of the PCs, the relationships between the original parameters are analyzed. The accuracy of the developed models in terms of fit to the training dataset ranged from 74.3% to 97.9%, with p-values < 0.05. The techniques incorporated in this study provided a comprehensive evaluation framework for monitoring wastewater treatment.