Avaliação do impacto de lodo de estação de tratamento de água (ETA) na qualidade das águas do arroio pilão de pedra

Abstract

The decanter wash water and the generated sludge are effluents from Water Treatment Plants (WTP) during the water treatment process. The generated effluent consists of organic and inorganic matter, microorganisms, and chemicals, which can contaminate the environment if not treated. The vast majority of water treatment plants discharge the effluents generated during the process in water bodies, which affects the quality of the water and can cause silting of rivers. The characteristics of the generated effluent must be evaluated to determine the impact on the receiving water bodies. The generated effluent varies according to WTP due to the coagulants and other chemicals used during the water treatment. Pilão de Pedra Stream located in the city of Ponta Grossa is a case of a water body that receives the effluent from WTP Sanepar, located in Jardim Carvalho. Five collections of one point of the Stream were carried out before the launch, the effluent itself, and another point after the launch between the periods of March 28, 2017 and July 3, 2017. Through physical-chemical analisis carried out in the effluent it can be observed that the maximum limit established by the legislation was extrapolated to the parameters BOD, COD and Sedimented Solids. For metals, the results obtained did not exceed the current legislation. The effluent was evaluated and compared with the legislation CONAMA 430/11 and SEMA 021/09, presenting high chemical load of aluminum, which is due to the coagulant used during the process. It was also possible to evaluate the impact that the effluent causes in the stream by comparing results with the legislation. One point of the Stream was evaluated before the effluent was launched, and another one after launching, and the results were compared with the CONAMA 357/05 legislation for Class II rivers. The Water Quality Index a statistical and environmental tool, was used to evaluate the stream data. It was noticed that point 1, before launching, showed better quality in the waters than point 2, after the effluent was released. The parameters of the waters that were not affected by the discharge of the effluent were total phosphorus, total nitrogen and fecal coliforms, which were diluted by the effluent, as this increased the water volume of the stream. In general, it can be verified that the released effluent impacts Pilão de Pedra Stream by altering important parameters of water quality.