BACTERIA BIOFOULING MEMBRANES NANOFILTRATION RESEARCH REVERSE OSMOSIS WATER TECHNOLOGY DEVELOPMENT

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Abstract

Membrane biofouling in nanofiltration (NF) and reverse osmosis (RO) applications is a major operational problem that leads to increased water production costs and potentially lower final water quality. Disinfection of the feedwaters is the most widely used membrane biofouling control method, but has been broadly unsuccessful in preventing significant biofilm formation on membrane surfaces. Even with high log removal of bacteria (e.g., 4-log), significant biofouling can happen because only a few bacteria are needed to colonize a surface and subsequently form a biofilm.

Alternate methods for biofouling control have been studied, including processes to remove nutrients or bacteria, changing the physical properties of the membrane surface, and coating the surface in biocides. These passive methods aim to decrease bacterial attachment or inactivate bacteria upon attachment but have fallen short of being widely applicable, cost-effective, and/or successful at controlling biofouling.

Our approach to this problem was to incorporate 2-aminoimidazoles (2-AIs) into the membrane matrix. 2-AIs are non-biocidal organic molecules that actively disrupt the ability of bacteria to detect and react to environmental stimuli, which keeps bacteria in a planktonic state and prevents their attachment to surfaces. These 2-AIs have inhibited biofilm formation of bacteria across different orders, classes, and phyla.

The specific objectives of this research were to: 1. determine whether a 2-AI would be amenable to incorporation into water purification membranes and maintain anti-biofilm activity once incorporated; 2. incorporate a 2-AI into the matrix of a commercial membrane; 3. evaluate the performance of the 2-AI-membrane in comparison to a control membrane lacking 2-AI in terms of water permeability, salt rejection, and biofilm inhibition.

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