Fractal Dimension Analysis of Flocs in Inline Coagulation-Microfiltration of Natural Organic Matter (NOM)

Abstract

Technology (NTNU), Norway2D fractal dimension analysis of inline-coagulation (IC) flocs in microfiltration of NOM using power-law relationship and boxcounting was done. Different process conditions represented by two types of coagulants (PIX and PAX) at four different hydraulic gradients (G-values of 4, 31, 98, and 300 s À1 ) were tested. Fractal dimensions of the flocs formed under the varying process conditions were found to be different. Overall NOM removal was found to be similar for all cases; however, the membrane filtration and fouling phenomenon observed were affected by the process conditions. This study has investigated the relationships between fractal dimensions, aggregate properties, and membrane fouling behavior observed. In general, PIX resulted in higher particle concentrations and the more irregular floc shapes resulted in high irreversible fouling, lower specific cake resistance, and a more compressible cake layer. In contrast, PAX resulted in lower particle concentrations and the more regular floc shapes resulted in a more reversible fouling, higher specific cake resistance and a less compressible cake layer. The fractal dimensions properties were found to be complementary for the analysis of membrane and cake resistances and can be useful tools in membrane fouling elucidation and minimization.

Application of low-field NMR in the study of flocculant-aided filtration process of coal tailings

“…The floc property mainly includes floc size and compactness, which can be investigated by combining the light scattering or image technique with fractal theory (Gungoren et al, 2020). The filter cake property can be characterized by observation techniques such as scanning electron microscope (SEM) and X-ray microtomographic techniques (Thapa et al, 2009;Lin and Miller, 2000;Raspati et al, 2013). However, contradictory conclusions are obtained regarding the effects of floc properties on filtration performance (Fitria et al, 2013;Cao et al, 2016), because both floc size and compactness significantly affect the filtration process, and it is difficult to predict which one is dominant.…”

State of the Art of Online Monitoring and Control of the Coagulation Process

“…Their results confirmed that there is a distinct effect of dosage on floc size. Raspati et al [55] investigated the influence of two coagulants under different mixing conditions on the fractal dimensions of flocs formed via in-line coagulation of NOM prior to microfiltration. They concluded that these floc parameters could be helpful in membrane fouling elucidation.…”