Microbiological contamination and water quality monitoring in the Puraquequara Basin, Manaus, Brazil: a predictive statistical approach

Indicator bacteria, such as thermotolerant and fecal coliforms, particularly Escherichia coli, are employed as markers of water pollution, and their presence in water sources is attributed to human fecal contamination. The Puraquequara Basin in Manaus, AM, serves as case study due to its exposure to diverse anthropogenic activities. Its contaminants include microbial pollutants such as thermotolerant coliforms, fecal coliforms and other pathogenic bacteria. Predictive models for water quality monitoring provide an effective means of identifying microbiological hazards and assessing potential health risks. This study aims to develop a predictive statistical model for estimating thermotolerant coliform and Escherichia coli concentrations based on physicochemical water parameters in the Puraquequara Basin. The study was conducted over a 10-month period, from August 2022 to June 2023. A total of 68 samplings were performed, during which 20 physicochemical and microbiological water quality parameters were analyzed. The physicochemical and biological parameters were analyzed following the standardized methodologies recommended by the Standard Methods for the Examination of Water and Wastewater. A Multiple Linear Regression (MLR) model was developed to assess the influence of physicochemical parameters on E. coli and total coliform contamination in the Puraquequara Basin. The evaluated parameters suggest that the Puraquequara basin is undergoing a contamination process, making this natural environment conducive to microorganism development. The concentration graphs for coliforms and E. coli display human activities that occur more frequently, such as during the drier months when visitation increases, which elevates microbiological contaminant levels at the sampling points closest to these areas. The MLR analysis was statistically significant, although it demonstrated limited explanatory power for both total coliform (R2 = 0.178, p <0.05) and I (R2 = 0.220, p <0.05) analyses. Selected parameters for total coliform were statistically significant.