Membrane Fouling and Cleaning

Membrane cleaning and disinfection is an important aspect in membrane operations particularly in food applications. Selection of cleaning agents impacts on membrane integrity, related costs and the environment. The objective this work is to improve the understanding of cleaning mechanisms for complex protein foulants using pure protein mixtures and Whey Protein Isolates as model feed. Comparisons were carried out on alkaline and acid as chemical cleaners as well as enzymatic cleaning agents to identify the optimal cleaning procedures. In addition to observing the flux recovery, the amounts and the compositions of foulants remained on the membrane surface at various cleaning stages were studied using advanced surface analysis such as mass spectrometry, gel electrophoresis, and LC/MS with trypsin digestion. One of the major outcomes of this study is the identification of the residuals after cleaning which could lead to targeted cleaning procedure to improved the overall cleaning efficiency. This work has lead to a successful ARC linkage grant in excess of a million dollars with industry in 2008.

In MBRs, sodium hypochlorite (NaOCl) is a common cleaning agent which recommended by membrane suppliers. Nevertheless, there is limited of publication on the effect of NaOCl and cyclical cleaning on membrane structure, aging, and lifetime. In an associated project, membranes are aged by NaOCl or exposed to repeated cleaning cycles and examined for any changes in its properties. Numbers of analysis technique are used, such as FTIR, porometer, SEM, XPS, tensile test, streaming potential and contact angle.

Gel electrophoresis used to show the disappearance small molecular weight residues from whey protein isolates (WPI) fouled ultrafiltration membranes during cleaning with sodium hydroxide solution.