Blocking laws analysis of dead-end constant flux microfiltration of compressible cakes

New blocking law models for dead-end constant flux microfiltration of colloids forming cakes that compressed in a linear and power law manner were derived. Constant pressure and constant flux experiments were performed using bacteria, colloidal silica, and treated natural waters to validate these new models and quantitatively verify blocking law predictions on the role of cake compressibility in microfilter fouling. Statistically invariant values of cake specific resistance and compressibility were obtained for constant flux and constant pressure operation for each feed suspension. This suggests that colloids formed cakes whose hydraulic resistance is dominated by a morphology that did not depend on their mode of deposition, confirming that the cake permeability was determined by the instantaneous pressure. Additionally, an inverse relationship between extracellular polymeric substances (EPS) secreted by bacteria and hydrodynamic flux restoration procedures was obtained demonstrating the importance of linking EPS to backwashing frequency when bacteria are present in the feed water. (c) 2006 Elsevier Inc. All rights reserved.