Análise do desempenho entre coagulantes orgânico e inorgânico no tratamento de efluentes provenientes da indústria de tintas

Abstract

The present study aimed to evaluate the efficiency of an organic coagulant, Moringa oleifera, and an inorganic coagulant, aluminum sulfate, applied to the processes of coagulation, flocculation, and sedimentation in the treatment of wastewater from a paint industry located in the state of Paraná, Brazil. The justification for this work is associated with the high pollutant load characteristic of this type of effluent, which poses technical challenges to meeting current environmental legislation and highlights the search for more sustainable treatment alternatives. Initially, the raw effluent was characterized in terms of its main physicochemical parameters, revealing high values of chemical oxygen demand, color, and turbidity. The experimental methodology consisted of applying a three-level factorial design, considering coagulant dosage and sedimentation time as independent variables. The tests were conducted using a Jar Test apparatus with a fixed agitation protocol, followed by analyses of pH, apparent color, turbidity, electrical conductivity, and chemical oxygen demand. The results indicated that aluminum sulfate demonstrated greater technical efficiency, achieving high removals of color and organic matter; however, it caused a significant reduction in pH, rendering the treated effluent incompatible with legal standards and requiring an additional neutralization step. Statistical analysis showed a significant influence of dosage, sedimentation time, and the interaction between these variables on the performance of the inorganic coagulant. Moringa oleifera, although presenting sustainable potential, showed limited performance in organic load removal and a considerable increase in electrical conductivity due to the coagulant preparation method, compromising its environmental viability. It is concluded that aluminum sulfate is more efficient for the treatment of the studied effluent, though operational adjustments are required, while Moringa oleifera did not prove to be a fully substitutive alternative for effluents with high pollutant loads.