Filtration method characterizing the reversibility of colloidal fouling layers at a membrane surface: analysis through critical flux and osmotic pressure

TL;DR

This paper introduces a filtration method to distinguish reversible and irreversible fouling on membranes, enabling the determination of critical flux through analysis of colloidal osmotic pressure and applied pressure cycles.

Contribution

A novel filtration technique based on square wave pressure to measure fouling reversibility and critical flux in membrane filtration processes.

Findings

Critical flux depends on colloidal destabilization and flow velocity.

Reversible fouling can be separated from irreversible fouling using the method.

Osmotic pressure analysis correlates with fouling reversibility.

Abstract

A filtration procedure was developed to measure the reversibility of fouling during cross-flow filtration based on the square wave of applied pressure. The principle of this method, the apparatus required, and the associated mathematical relationships are detailed. This method allows for differentiating the reversible accumulation of matter on, and the irreversible fouling of, a membrane surface. Distinguishing these two forms of attachment to a membrane surface provides a means by which the critical flux may be determined. To validate this method, experiments were performed with a latex suspension at different degrees of destabilization (obtained by the addition of salt to the suspension) and at different cross-flow velocities. The dependence of the critical flux on these conditions is discussed and analysed through the osmotic pressure of the colloidal dispersion.