Acompanhamento da evolução da Distribuição de Tamanho de Partículas (DTP) no processo de floculação de água com cor elevada

Abstract

This article presents an evaluation of the flocculation process by continuous follow-up of the floc formation in a static reactor Jar Test throughout image acquisition of flocs to study the Particle Size Distribution (PSD) using different Flocculation Speed Average Gradients ​​(Gf) and Flocculation Times (Tf). The studied water was prepared with 100 uH of high apparent color by using humic acid. The flocculation process was conducted in a Jartest equipment using aluminum sulphate as coagulant, and sulfuric acid and aluminum hydroxide as pH correctors. This work was divided into four parts: construction of the coagulation diagram, capitation, treatment and analysis of the images. In the first part, based on a coagulation diagram with sedimentation velocity of 1 cm/min, a point was selected in which the predominant mechanism was scanning, with 89% apparent color removal, coagulant dosage of 9.5 mg/L and pH of 6.18. In the second part, 40 images were captured for different Gf and Tf. In the third part, the open source Image J was used for image treatments to determine the characteristics of the flocs. Lastly, in the fourth part, the DTP data obtained from the previous phase were studied. The increase of Gf, was it was expected, due to the increase of the shear rates of the flocs, there is a formation of lower size flocs; on the other hand, the decrease of Gf, there is a tendency to form larger size flocs, in this case, with great concentration of intermediate flocs. It was observed a balance of both formation and rupture rate of the flocs throughout the flocculation time, being able to verify that the stabilization plateau was reached.