Eficiência de diferentes materiais filtrantes em sistema de filtração rápida no tratamento de efluente de indústria de tintas

Abstract

The paint industry generates effluents with high organic load, pigments, solvents, and toxic compounds, requiring efficient and environmentally safe treatment methods. Physicochemical processes, such as direct filtration, have stood out due to their simplicity and satisfactory performance, especially when associated with alternative filtering materials, such as loofa sponge. In the coagulation stage, natural coagulants such as Moringa oleifera have emerged as sustainable alternatives, whereas aluminum sulfate remains widely used due to its effectiveness. This study evaluated the efficiency of Moringa oleifera and aluminum sulfate as coagulants in the treatment of paint effluents, analyzing physicochemical parameters such as pH, turbidity, apparent color, and chemical oxygen demand (COD). Coagulation, flocculation, and sedimentation tests were carried out, followed by filtration using sand and loofa sponge filter beds, in order to assess the influence of filtering materials in the final treatment stage. Filtration was conducted in laboratory-scale columns made with sand with 0.850 mm granulometry and loofa sponge. The results showed that the Moringa oleifera seed-based coagulant presented lower performance than aluminum sulfate in terms of apparent color and turbidity removal. During sedimentation, the highest apparent color removal efficiencies were 98.46% for Moringa oleifera, resulting in a residual value of 351.75 mg PtCo L⁻¹, and 99.99% for aluminum sulfate, with a final value of 1 mg PtCo L⁻¹. For turbidity, the maximum removal efficiencies were 58.78% for Moringa oleifera, corresponding to a residual value of 149.6 NTU, and 96.25% for aluminum sulfate, with a final turbidity of 13.6 NTU.Despite its lower performance, the natural coagulant stands out as a sustainable alternative with reduced impact on pH. Regarding filtration, the loofa sponge filter presented satisfactory results, although lower than those obtained with the sand filter combined with aluminum sulfate. Maximum removal efficiencies obtained using Moringa oleifera reached 95.57% for turbidity and 99.87% for apparent color, while aluminum sulfate achieved 98.15% and 99.94%, respectively. For COD removal in the treatment with Moringa oleifera, the sand filter achieved an efficiency of 98.64%, whereas the loofa sponge filter reached 89.80%. Therefore, filtration proved essential for achieving adequate treatment performance for paint industry effluents, and although less efficient than sand, loofa sponge demonstrated feasibility as an alternative filtering medium.