Disinfection of a polyamide nanofiltration membrane using ethanol

It is imperative that nanofiltration membranes are disinfected before they are used for laboratory-scale bacterial adhesion or biofouling experiments, yet currently no suitable disinfection protocol exists. This study aimed to determine if an ethanol treatment at a minimum inhibitory concentration (MIC) could be used to effectively disinfect nanofiltration membranes without altering membrane properties which could affect research. Two strains of bacteria, Pseudomonas fluorescens and Staphylococcus sp., were exposed to a range of ethanol concentrations to determine the MIC required for a 4log10 reduction in bacteria. In parallel, ethanol's effects on the filtration, surface and mechanical properties of a Dow Filmtec NF90 membrane were analysed. A 1.5 hour treatment with 40% ethanol was shown to effectively disinfect the membrane without significantly affecting any of the membranes properties tested. This treatment protocol can now be safely used to disinfect the studied membrane prior to bacterial adhesion or biofouling experiments. This study also acts as a guideline for researchers using other membranes to determine a suitable disinfection protocol for their needs.