Ozonização como uma ferramenta alternativa no tratamento de água subterrânea na bacia hidrográfica do Rio Sapucaí/MG: influência da qualidade de água ferruginosa

Abstract

Although essential for the conservation of life and human activities, water consumption is significantly demanded across the planet, which has drastically affected its quality and quantity of surface water. Such demand has accelerated more with population growth, disorderly urbanization and agricultural and industrial expansion. In this scenario, the abstraction of water from underground wells presents itself as a potential alternative to saving water worldwide. However, many users of groundwater have been faced with a biochemically complex situation, the presence of a high concentration of iron, called ferruginous water, as is the case in the southern region of Minas Gerais. This mineral, abundant on the planet, when in excess in the water supply causes several problems for consumers, such as damage to hydraulic equipment, clogging, obstruction, color change, taste and odor of water, stains on clothes and sanitary appliances, interruption of water supply, loss of the well, among others. Considering the information previously presented, this work proposed to carry out a preliminary experimental investigation, in an artesian well, located in the hydrographic basin of the Alto Rio Sapucaí, in the south of Minas Gerais, related to the removal of iron from ferruginous underground water, as well as other chemical substances, physical and microbiological variables, namely color, turbidity, pH, iron II and iron III, manganese, total and fecal coliforms and iron bacteria, through the ozonation technique, as an alternative solution, a technology that has been highlighted in recent years. Ozone, as a powerful oxidizing agent, was used in this study at a dose of 1.3 gO₃/h, and was observed at 4 different times, namely, initial time (t0), after 10 minutes (t1), after 20 minutes (t2) and after 30 minutes (t3), to obtain concentrations below their limit values for drinking water. The results surprised that ozonation presents 100% efficiency in eradicating the thermotolerant and total bacteria studied, in the first 10 minutes of exposure, thus meeting the potability standards of Ordinance GM/MS n° 888/2021.After an exposure time of 30 minutes, it can be observed that the variable color presents a reduction of 22.37%, of turbidity of 6.35%, of the presentation of iron II to iron III of 100%, of manganese of 28.33% and increase of the pH variable by 27.16%. Although ozonation caused a reduction in the values of the previous variables, it was not enough to reach the maximum allowed by the Ordinance, only the manganese variable. In general, the ozonation method proposed for this study, and applied to the groundwater supplied by this well, was not efficient in allowing the use of this water for drinking purposes, which does not prevent its use in less noble human activities, since this ozonized water does not present bacteriological contamination like raw water.