Effect of ultrafiltration membranes modifications by chitosan on humic acid fouling

In the last few decades, membrane technology has been extensively utilised in many water treatment applications. Nevertheless, wider implementation of this technology is hindered due to membrane fouling phenomenon. To address this major drawback, membrane modification has been widely studied to increase the membrane resistance to fouling. This paper studies the effect of using chitosan solution to modify ultrafiltration PAN and PVDF membranes and evaluate their filtration of humic acid (HA) solution and their fouling resistance capabilities. Two modification methods were evaluated, namely immersion and flow through methods. The hydrophilicity of both membranes was significantly improved due attachment of hydrophilic chitosan particles on the surface of the membrane. The flow through modification method enables deposition of chitosan particles inside the membrane pores enhancing the hydrophilicity of the membrane compared with the immersion method. The deposition of chitosan on both membranes reduced their water permeability. However, both modified membranes exhibited enhanced fouling resistance property. Furthermore, their rejection of HA was improved, particularly with PVDF membranes.