Proposal of a wastewater quality index using a weighted arithmetic mean model/Propuesta de indice de calidad de agua residual utilizando un modelo aritmetico ponderado/Proposta de indice de qualidade da agua residual utilizando um modelo aritmetico ponderado

Wastewater management is a worldwide issue and Mexico is no exception. Only 17.9% of Mexico City's wastewater is treated and most of it is diverted out of the Mexico Basin through a drainage network. Before treated or diverted, it is necessary to know the wastewater quality so as to prevent adverse effects in the treatment plant or drainage network. One way to identify, quantify and report on the quality of wastewater is through a quality index for water entering into the drainage network. In this study, a Wastewater Quality Index (WQI) is proposed, using a weighted arithmetic mean model. A numerical scale to classify water based on the effects on the drainage is also presented. The results obtained from some typical industries located in Mexico City showed that electroplating industry was identified as the most contaminant one, with a WQI of 80.