Influência do local de amostragem na qualidade da água da chuva em duas regiões de Curitiba

Abstract

Aiming at water sustainability, this research is based on the importance of using rainwater for non-potable purposes as a means to reduce the demands for treated water in urban centers, also providing a relief effect on the drainage systems of large cities and reducing the occurrence of flooding. The general objective is to verify how the characteristics of land occupation and demographic density, influence the quality of rainwater collected on the roofs of homes in two regions of the city of Curitiba. For this, through sampling collected directly from the atmosphere, the first flush from the roofs, the water collected from the roof after the first discharge and collections made already in the drainage system, it is intended to evaluate the parameters of rainwater quality in terms of pH, alkalinity, total solids, turbidity and total coliforms and discuss the possibilities of use. The two regions for sample collection were the UTFPR Campus Ecoville and the Military Police College. Precipitation was measured by rain gauges developed by the authors and compared to conventional rain gauges, where it was found that the “homemade” rain gauges adequately served the purpose. The rain gauges were installed and daily rainfall was measured in case of rain. In order to compare the two study areas, data referring to the demographic density of the CIC and Portão districts of the city of Curitiba in which the systems were installed were considered. Rain collection systems were built in both locations, using gutters, pipes and PVC fittings só that this system routes the water drained from the roof first to a disposal tank to partially remove the impurities deposited on the roofs and gutters. Samples were collected for the four points of each of the areas, turbidity and total solids analysis were performed at Labsan (UTFPR Sanitation Laboratory) and the other parameters were analyzed at LATAM laboratory (Laboratory of Toxicological and Environmental Analysis). All tests performed on the samples followed internationally recognized standards. The results show that there is a decline in the quality of rainwater during runoff to the drainage system. Regarding alkalinity, 87.5% of the samples showed lower values than those found in natural waters from 30 to 50 mg / L. Fecal coliforms were found in 92.3% of the analyzed samples. The pH corresponded to the expected values between pH 6 and pH 8, in order to protect the distribution networks. As for the constant solids in the rainwater of the first discard, a greater amount of solids was perceived at this point. Turbidity rates ranged from 2 to 10 depending on the drought period that preceded the rain. The results obtained in this research conclude that there is influence of the area on the quality of rainwater.