Comportamento da cafeína em meio não saturado, utilização de ensaios de coluna para sedimentos da formação barreiras e depósitos litorâneos

Abstract

Nowadays, groundwater is the main source of supply for several Brazilian cities. Overexploitation and constant contamination of these sources can lead to serious consequences with regard to the qualitative and quantitative aspects. One way of verifying the origin of a potential contaminant is the presence of caffeine, since it is a direct indicator of contamination by domestic effluents. In this sense, this study tried to find to understand a relationship between the amount of coffee found in groundwater and the amount that is released on the surface. To this end, it was necessary to analyze the presence of caffeine in groundwater wells and understand the behavior in soils unsaturated, using sediments from outcropping geological units of the Barreiras formation and Depositos Litorâneos, where were subjected to column tests in three different sizes (0.5 / 1.0 and 2 meters) and the pre-defined coffee solution was launched in each of them (for each type of specific sediment) and collected at its end, thus allowing to obtain the retention capacity of these sediments. The results shown for the Barreiras formation, caffeine was retained only in the first meter of sediment, close to 100 mg / l, after that these sediments were no longer able to act in their removal. On the other hand, the Depósitos Litorâneos formation progressively remove a caffeine, allowing the deduction of the greater the depth of sediment, the greater its capacity to retain. When these results were analyzed with the amount of coffee present in the groundwater wells, the value below the limit of quantification of analysis, deducted for the Depositos Litorâneos, the amount of coffee released in the well waters was less than 350 mg / L. For the Barreiras formation, an amount was less than 100 mg / L or, if it was higher, a saturated zone was responsible for retaining the same.