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New insight into hydrodynamic and cake erosion mechanism during rotating-disk dynamic microfiltration of concentrated bentonite suspensions at different salinity conditions

Movahedi, H ; Sharif University of Technology | 2022

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  1. Type of Document: Article
  2. DOI: 10.1016/j.seppur.2022.121844
  3. Publisher: Elsevier B.V , 2022
  4. Abstract:
  5. The present study investigates the dynamic filtration of concentrated slurry fluids containing colloidal clay particles under different salinity, shear flow, and flux rate conditions. The dynamic filtration study was carried out by the filtration cell equipped with a rotating disk to apply shear stress over the membrane surface. A 3D CFD simulation has been implemented to model the hydrodynamic flows inside the filtration cell to obtain the wall shear stress (WSS) on the membrane surface at different disk rotation speeds. The thickness and surface patterns of fouling were captured utilizing a surface profilometer. First, the cake-filtration model was used to predict the flux rate and fouling thickness under static filtration. Then, the corresponding filtrate flux at stabilized cake thickness under shear flow conditions was calculated. The results showed that increasing the suspension salinity causes the reduction of rheological properties and increases the cake permeability due to the compression of the electrical double layer around clay particles. The results also revealed that increasing the flux rate condenses the cake and reduces erosion. Finally, a model for predicting the rate of fouling removal during dynamic filtration was developed using nonlinear regression. The results showed that a sigmoidal function with appropriate accuracy (R2>0.96) could describe fouling thickness patterns with WSS. Moreover, the mean cake thickness decreased by 80% as the WSS increased from 0 to 2 Pa, where the rotating disk speed increased from 0 to 500 rpm. © 2022 Elsevier B.V
  6. Keywords:
  7. Clay suspension ; Bentonite ; Computational fluid dynamics ; Fouling ; Hydrodynamics ; Microfiltration ; Rotating disks ; Shear flow ; Shear stress ; Suspensions (fluids) ; Cake erosion ; Clay particles ; Clay suspensions ; Condition ; Dynamic filtration ; Filtrate flux ; Flux rates ; Rotating disc ; Wall shear stress ; Wall-shear stress ; Erosion
  8. Source: Separation and Purification Technology ; Volume 300 , 2022 ; 13835866 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S1383586622013995