Avaliação de desempenho de coagulantes orgânicos e inorgânicos em amostra de água natural oriunda da barragem Araçagi

Abstract

Water is a natural and precious resource for survival, but in order for it to be consumed and used for domestic purposes, it must undergo a multi-stage treatment process at a water treatment plant (WTP). Another important factor related to water is that it must be treated as a resource that can become scarce over the years due to periods of drought, improper dumping of materials in landfills, rivers and lakes that can contaminate groundwater and springs, among other factors. The geology of a region that contains springs that supply water treatment plants, in turn, can directly influence the quality of the raw water to be treated and, in some situations, the soil of this type of dam, such as the Araçagi dam, can contain several metals, including iron and manganese. The presence of these metals causes several problems in WTPs, which can make it difficult to treat water using full-cycle WTPs. To this end, new treatment techniques are needed to improve water treatment. Coagulation is one of the main steps in water treatment and requires further research to improve treatment in WTPs. Considering the importance of water treatment, this study aimed to evaluate the efficiency of the action of several organic coagulants (tannin-based) at different concentrations, such as Angico, Cajueiro, Jurema and Tanfloc. The inorganic coagulant Aluminum Sulfate was also analyzed. Through treatability tests with these coagulants, it was possible to observe an improvement in water quality, evaluated by means of the physical-chemical parameters of natural water, such as turbidity, apparent and true color, variations in pH, and removal of iron and manganese metals, on a laboratory scale. The study found that, among all the coagulants used, organic coagulants performed best, achieving up to 97% manganese removal for the Angico-based coagulant and 75% iron removal using the Tanfloc coagulant.