DETERMINAÇÃO DE CAFEÍNA EM ÁGUAS SUPERFICIAIS COMO INDICADOR DE CONTAMINAÇÃO POR ESGOTO DOMÉSTICO

Abstract

Caffeine is suggested as a chemical indicator for the presence of domestic wastewater in freshwater systems, although it is not included in quality monitoring programs. Thus, it can be an excellent indicator of contaminant organic residues in urban streams frequently affected by sewage in Brazil. In this sense, the objective of this study was to evaluate the potential of caffeine as an indicator of domestic sewage contamination in surface waters of the Pitangui River Basin, in the city of Ponta Grossa, Paraná, Brazil. In the study, after the validation of the analytical methodology, a relationship was sought between caffeine in surface water and the effluent supply. Eight (8) surface water samples were collected in the Verde River, in the urban area (P1), upstream (P2) and downstream (P3) of the Sewage Treatment Station (STS), and two treated effluent samples of the STS. For the determination of caffeine, High Performance Liquid Chromatography (HPLC) was used after solid phase extraction in C18/18 cartridges with extractor volume of 6ml. The physical-chemical evaluations of the surface samples showed a decline in the water quality after the STS treated effluent input, observed mainly through the concentrations of total phosphorus (PT) and Biochemical Oxygen Demand (BOD) levels, above the established limits by legislation, after the effluent. Caffeine was quantified at points P2 and P3, with mean concentrations of 121,0 e 144,0 μg L-1. The results showed the relationship between the presence of caffeine and impaction by the inflow of raw sewage, or by the treated effluent from the STS.