Caracterização microbiológica e físico-química da água de consumo e de bebedouros de uma instituição de ensino superior no vale do Araguaia - MT

Abstract

Water is an essential resource for human survival and well-being, playing a fundamental role in many daily activities. In higher education institutions, the availability of drinking water is essential not only for the hydration of students and staff, but also for maintaining hygiene and collective health. Drinking fountains, widely used in these environments, provide easy and quick access to water, but can pose health risks if they are not properly sanitized and the quality of the water provided is not monitored. In view of this, this study aimed to evaluate the microbiological and physical-chemical quality of drinking water and drinking fountains at a higher education institution in the Araguaia Valley. A total of 74 samples were analyzed using techniques established by the American Public Health Association (APHA, 1995; 2001), CONAMA Resolution No. 357/2005 and GM/MS Ordinance No. 888/2021, including the use of the Most Probable Number (MPN) method with Lauryl Sulfate Tryptose Broth and Durham tubes for detection of total coliforms, thermotolerant coliforms and Escherichia coli, in addition to Petrifilm™ 3M plates for quantification of Staphylococcus aureus, mesophilic aerobic bacteria, enterobacteria, fungi and yeasts. The analyses were conducted at the Food Microbiology Laboratory of the Araguaia University Campus of UFMT. The microbiological analysis of the water included the counting of total coliforms, thermotolerant coliforms and Escherichia coli. The results revealed that for total coliforms, 17 of the 37 samples analyzed (45.9%) presented concentrations between 3.6 and 460 MPN/mL. As for thermotolerant coliforms, 19 of the 37 samples analyzed (51.4%) presented values above 1,100 MPN/mL. The presence of E. coli was identified in 4 of the 37 samples (10.8%). Regarding the drinkers, for total coliforms, its presence was observed in 19 of the 37 samples (51.4%) and quantification of thermotolerant coliforms in 24 of the 37 samples (64.9%), with counts ranging from 3.0 to >1,100 MPN/cm². The presence of E. coli was confirmed in 5 samples (13.5%), in disagreement with the recommendations of Resolution GM/MS No. 888/2021. Enterobacteriaceae levels ranged from 1.7×10⁰ to 4.4×10² CFU/cm². High counts of mesophilic aerobic bacteria were observed in two samples, ranging from 1.14×10³ to 2.86×10⁴ CFU/cm². Fungi and yeasts were present at concentrations of 1.5×10⁰ to 8.5×10² CFU/cm². In addition, Staphylococcus aureus was detected in 12 of the 37 samples (32.4%). Regarding the physicochemical parameters of the water, the analysis included hardness, pH, acidity, alkalinity and chlorides. The results were compared to the limits established by CONAMA Resolution No. 357/2005 and GM/MS 888/21. The samples were in compliance with the hardness and chloride parameters. For acidity and alkalinity, although there are no limits defined by law, the values obtained ranged from 2.21 to 33.57 mg/L and 2.09 to 13.59 mg/L, respectively. As for pH, only 19 of the 37 (51.4%) samples analyzed presented values within the recommended standards. It was found that only 18 of the 37 water samples (48.6%) were in compliance with current legislation regarding microbiological parameters. These results demonstrate the urgent need to implement good hygiene and maintenance practices for drinking fountains, as well as continuous microbiological and physical-chemical monitoring of the supply system. The adoption of such measures is essential to ensure the supply of safe and potable water to the institution's users.