PSD and Fractal Dimension for flocculation with different parameters and ferric chloride, aluminium polychloride and aluminium sulfate as coagulants

In conventional water treatment, coagulation and flocculation stages play a very important role, once they are related to the success of the subsequent processes. Among the techniques applied to analyze these stages, analysis of images that aims to provide information related to the formed particles, such as parameters of Particle Size Distribution (PSD) and Fractal Dimension (D-f), stands out. Thus, this study aimed to compare the evolution of these parameters and the D-f along coagulation and flocculation processes, for different chemical coagulants and different conditions. It was verified that the parameter beta(1) of PSD tends to increase during time, indicating formation of larger particles, until the establishment of its stabilization level. It was also observed that for higher coagulant dosages and, especially, when turbidity in water was higher and Ferric Chloride and Aluminium Polychloride were used, the parameters beta(1) of PSD, after initial growth stage, decrease for later dynamic stabilization. As for D-f, it was concluded that there is an initial tendency of growing, followed by a stabilization of its value during most of the flocculation process, indicating that the structural organization of the floc is not necessarily linked to the variations in its size. These conclusions can help further investigations and studies on coagulation/flocculation processes in order to understand how flocs behave over time, under the different chemicals used.

Automated summary

The study compared the evolution of PSD and D-f parameters during coagulation and flocculation processes with different chemical coagulants and conditions. It was found that the PSD beta(1) parameter tends to increase over time, indicating formation of larger particles, but decreases after initial growth with higher coagulant dosages and use of certain chemicals. The D-f parameter stabilizes during most of the flocculation process, suggesting that the structural organization of flocs is not necessarily linked to variations in size.