Title

Variations In Backwash Efficiency During Colloidal Filtration Of Hollow-Fiber Microfiltration Membranes

Keywords

Backwashing efficiency; Cake layer structure; Colloidal fouling; Microfiltration; Water treatment

Abstract

A series of filtration experiments was performed systematically to investigate physical and chemical factors affecting the efficiency of backwashing during microfiltration of colloidal suspensions. In this study, all experiments were conducted in dead-end filtration mode utilizing an outside-in, hollow-fiber module with a nominal pore size of 0.1 μm. Silica particles (mean diameter = 0.14 μm) were used as model colloids. Using a flux decline model based on the Happel's cell for the hydraulic resistance of the particle layer, the cake structure was determined from experimental fouling data and then correlated to backwash efficiency. Modeling of experimental data revealed no noticeable changes in cake layer structure when feed particle concentration and operating pressure increased. Specifically, the packing density of the cake layer (1-cake porosity) in the cake layer ranged from 0.66 to 0.67, which corresponds well to random packing density. However, the particle packing density increased drastically with ionic strength. The results of backwashing experiments demonstrated that the efficiency of backwashing decreased significantly with increasing solution ionic strength, while backwash efficiency did not vary when particle concentration and operating pressure increased. This finding suggests that backwash efficiency is closely related to the structure of the cake layer formed during particle filtration. More densely packed cake layers were formed under high ionic strength, and consequently less flux was recovered per given backwash volume during backwashing. © 2005 Elsevier B.V. All rights reserved.

Publication Date

3-20-2005

Publication Title

Desalination

Volume

173

Issue

3

Number of Pages

257-268

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/j.desal.2004.07.049

Socpus ID

18144386236 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/18144386236

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