PROPOSITION OF A NEW APPROACH FOR ESTIMATING DRY MASS GENERATED IN WATER TREATMENT PLANTS IN PARANÁ/BR (Atena Editora)

Abstract

Water treatment plants (WTPs) that operate through conventional treatment processes produce large quantities of sludge, called WTP sludge, which are classified as solid waste in countries in Latin America, the European Union and the United States. An important step in sludge management consists of reducing the volume to be disposed of, requiring the correct quantification of sludge produced at the stations, very often carried out using empirical equations from the literature, which consider the characteristics of raw water, such as total suspended solids. (SST) or Turbidity (T) together with a multiplication coefficient to obtain SST, and reagents added in water treatment. Due to the qualitative differences in the water used for supply and the different characteristics of the reagents, the objective of the present work was to evaluate the applicability of these equations and propose a new approach for estimating the dry mass generated in ETAs located in the Pirapó Hydrographic Unit (UH), Paranapanema 3 and 4 in the state of Paraná, based on real correlations between T and SST. For this, a history of data on these parameters in raw water from the mentioned UH was used and, with the application of statistical methods, a new equation was obtained for determining TSS from T. The precipitates of the chemical products were also verified used in the treatment, based on stoichiometric relationships with water, to compose the portion of sludge generated from the products, which, added to the portion resulting from the quality of raw water, gave rise to the new equation for estimating the dry mass generated in ETAs in this region. To compare the results obtained with the new equation with those from the literature equations, an ETA was selected in this region and real measurements of the dry mass generated were made from the dewatered sludge destined. The results obtained with the measurements and the application of literature equations had differences of 28 to 65%, depending on the equation, significantly greater than the difference obtained when comparing the real values with the new proposed equation, of -0, 64%. Considering the local characteristics of the water and the chemical reagents used in the treatment is, therefore, essential for a more accurate calculation of sludge production in ETAs. It is believed that the new approach proposed in this work can improve the design of sludge treatment plants, especially in new ETAs, where real measurements are not possible to determine the dry mass generated, a very common situation in Brazil.