Avaliação da tendência de incrustação por CaCO3 em tubulações a partir de águas subterrâneas do estado do Ceará

Abstract

Water covers about 70% of the planet's surface, and is a very important resource for the maintenance of life on Earth. Populations around the world have been suffering increasingly with hydric crisis, mainly related to flooding, hydric resources pollution and drought. In Brazil, the main region affected by drought is the North East, region assigned as semiarid. On regions with water shortage, beside the economic use of the hydric sources and springs existents, is indispensable the Search for new water sources, being the water well drilling a viable and more disponible than rain water collection, because rain is sporadic and the rainy season lasts only a few months a year. After collected, the water must be distributed to the population through Water Distribution Systems, composed in all of its section by pipe lines. Naturally presenting ionic species with low solubility on its composition, underground Waters may cause scales formation in this piping systems, causing efficiency reduction or clogging of it. On this work, physical-chemical tests were performed to measure alkalinity, calcium concentration, pH and conductivity of 80 underground water samples collected on 14 regions from the state of Ceará. These parameters were used to estimate the tendence of these waters to form or solubilize CaCO3 scales. 91,5% of the 80 samples tested presented Saturation Index (SI) higher than 0, evidencing a natural tendency of forming scales, while 7,5% of the samples presented SI lower than zero, implying in a tendency to solubilize them. Results showed that most part of water sources from the state of Ceará tend to form scale in piping systems, pointing to the caution that must be present in use of Chemical additives to prevent the formation, increasing the water distribution systems lifespan.