Estudo da eficiência granulométrica no processo de filtração direta com aplicação de coagulantes no tratamento de água

Abstract

Due to the technological advancement and increased population, the demand for water has increased significantly, thereby increasing the care of it treatment. The use of chemical coagulants in water treatment generates discussion, as these chemicals can be toxic to human health. Because of these problems there is an interest in finding new compounds as an alternative to the use of coagulants, such as Moringa oleifera seed extract. Another important factor to consider in water treatment is the granulometry of the filter material, in which different sand particle sizes influence the quality of the treatment. This study aims to compare the performance of the Moringa oleifera seed extracted coagulant and chemical aluminum sulfate coagulant in the process of coagulation / flocculation / sedimentation / filtration in water treatment, and check the best sand granulometry used in the process direct filtration. The tests were carried out in the Jar-Test equipment followed by direct descendant filtration. The concentration for both coagulants was 300 mg.L-1. In the filtration were used three different granulometries: G1 (up to 0.425 mm), G2 (0.425 to 850 mm) and G3 (0.850 to 1.70 mm). The parameters analyzed were: pH, apparent color, turbidity, electrical conductivity, temperature and total solids. After the tests, it was concluded that in general the natural coagulant was more efficient in the removal of the analyzed parameters. During the sedimentation, the natural coagulant removed 72% of apparent color, 75% of turbidity and 60% of total solids, while aluminum sulfate removed 25%, 37% and 58%, respectively. After filtration, the removal efficiency of these parameters increased significantly, where the granulometry G3 showed the best results for natural coagulant (94%, 98% and 74%) and G2 showed better results for the chemical coagulant (90%, 96% and 74%). Even with close values, granulometry G3 showed to be moderately better. G1 was also efficient in the treatments, but with smaller removal values in relation to G2 and G3. In general, treatment using Moringa oleifera seed extract associated with granulometry G3 filtration (0.850 to 1.70 mm) was the one that obtained the most satisfactory results, proving the efficiency of the natural coagulant in water treatment.