The contribution of the Guarulhos Municipality (São Paulo State) to the water quality of the Alto Tietê System

Abstract

The population growth in Guarulhos (São Paulo State) has been above the average for the São Paulo Metropolitan Region (RMSP). The Baquirivu-Guaçu River Basin (BHRBG), where the Baquirivu-Guaçu River is located, is exactly the urban expansion vector of Guarulhos municipality and neighboring areas. This study presents an analysis of the quality of the Baquirivu-Guaçu River waters at the entrance and at the exit of the Guarulhos municipality, in order to assess the effects of the implementation of sewage treatment plants (STPs) and land use on the Baquirivu-Guaçu River water quality between 2010 and 2014. For that were prepared the land use maps in the period analyzed, an analysis of the functioning of STPs in the study area, a statistical analysis of the Water Quality Index (WQI) and its parameters at different points of the river. The data relative to the Baquirivu-Guaçu River physico-chemicals and microbiological analyses indicate a much lower water quality in the exit of the Guarulhos municipality (WQI=16), when compared to that coming from the Arujá municipality (WQI=32). The mean values highlighted for BOD, DO, TU, TS and FC parameters indicate a considerable worsening of the Baquirivu-Guaçu River waters at point BQGU 03850. The values of TN, TP and pH parameters both at the entrance and exit of the basin are close. The analysis of land use evolution and water quality shows the consequences of an improper process of urban growth in the basin and that the domestic and industrial polluting sources represent considerable risk to water quality, attesting that the sanitation works carried out up to now have not been effective in reducing the polluting charges launched in the Baquirivu-Guaçu River waters.