Disinfection of a polyamide nanofiltration membrane using ethanol

Abstract

PublisherElsevierItem record/more information http://hdl.handle.net/10197/4556 Publisher's statement þÿ T h i s i s t h e a u t h o r s v e r s i o n o f a w o r k t h a tAbstract 22 It is imperative that nanofiltration membranes are disinfected before they are used for 23 laboratory-scale bacterial adhesion or biofouling experiments, yet currently no suitable 24 disinfection protocol exists. This study aimed to determine if an ethanol treatment at a 25 minimum inhibitory concentration (MIC) could be used to effectively disinfect nanofiltration 26 membranes without altering membrane properties which could affect research. Two strains of 27 bacteria, Pseudomonas fluorescens and Staphylococcus sp., were exposed to a range of 28 ethanol concentrations to determine the MIC required for a 4log 10 reduction in bacteria. In 29 parallel, ethanol's effects on the filtration, surface and mechanical properties of a Dow 30 Filmtec NF90 membrane were analysed. A 1.5 hour treatment with 40% ethanol was shown 31 to effectively disinfect the membrane without significantly affecting any of the membranes 32 properties tested. This treatment protocol can now be safely used to disinfect the studied 33 membrane prior to bacterial adhesion or biofouling experiments. This study also acts as a 34 guideline for researchers using other membranes to determine a suitable disinfection protocol 35 for their needs.36 37 38 39 40 41 42 43 44 45 Keywords 46 Disinfection, ethanol, pre-treatment, MIC, nanofiltration 47 51Nanofiltration research in these areas has focused on two main objectives: 1) maximising 52 permeation while achieving a high level of rejection, and 2) maintaining the longevity of 53 filtration properties, primarily through the mitigation of fouling [4, 5]. 55Of the several types of fouling that occur, the adhesion and proliferation of microorganisms 56 on the membrane known as biofouling is particularly problematic. It is of utmost importance 57 that fundamental research in which bacterial pure cultures are used, for adhesion and 58 biofouling experiments, be conducted on sterile surfaces. Biofouling experiments performed 59 on non-sterile surfaces are at risk of experimental bias, resulting in unspecified multispecies 60 biofilms. Virgin membranes received from manufacturers may be initially clean but are non-61 sterile, representing a potential contamination source for controlled adhesion and biofouling 62 studies in which pure cultures are utilised. 63 64 Sterilisation can be achieved by chemical, thermal, and irradiation means. There is a major 65 emphasis on sterility in microbiological research and yet there is little research into 66 sterilisation techniques for NF and reverse osmosis (RO) membranes. Although a number of 67 different research groups have reported the use of thermal [6, 7] and chemical [8-11] 68 sterilization procedures on membranes, few have considered the damaging effects that such 69 treatments could potentially have. This comes at notable risk considering the available 70 information showing the th...

The effect of ethanol pre-treatment upon the mechanical, structural and surface modification of ultrafiltration membranes

“…Heffernan et al [21] demonstrated that a polymeric nanofiltration membrane (polyamide supported on PSU, which was supported on polyester) showed similar relaxation behaviour to the samples examined here. It was demonstrated that the polyamide top layer had swelled to a greater degree than the PS.…”

“…Membranes following ethanol treatment also showed some flattening and relaxation (they are normally stored in rolls, and thus their natural shape is curved with the top layer on the concave side). Differential swelling of layers of composite membranes such as these has been shown to lead to deformation [21,22].…”

Priming of microbial microcystin degradation in biomass-fed gravity driven membrane filtration biofilms

“…The biofouling monitors, the permeate collection bottles and their connections were all sterilized. The membrane was first soaked in 40 % ethanol for 1.5 h and then placed in sterile deionized water overnight prior to the experiments [31].…”

Use of a water-based probiotic to treat common gut pathogens

“…In this case, however, colony counts at 48h ( Figure 6) show that the pathogen has not been completely eradicated; its numbers reduced to 10 4 cfu/mL. However, in evaluating antimicrobial effects, a 3-log reduction is considered to be a significant reduction (Usacheva et al, 2014, Heffernan et al, 2013, Koh et al, 2013. S. sonnei has been reported to be very susceptible to acidic environments.…”