Isolation and Control of Membrane Filter Degrading Microorganisms

The Roswell Test Facility reverse osmosis testing program was plagued with premature failure of cellulose acetate reverse osmosis membranes. Microbial degradation of the membranes was thought to be the cause. This study was conducted to identify the microorganisms responsible for the problems, locate the source of contamination, and prevent future contamination.

Microorganisms were isolated from various membranes and waters and tested for their ability to degrade cellulose acetate preparations and membrane strips. None of the microorganisms isolated or enrichment cultures from facility membranes were found to degrade cellulose acetate. The microorganisms isolated were common soil and water inhabitants. Those membranes with high microbial populations generally had good salt rejection capabilities while those membranes with low microbial populations had the greatest decline in salt rejection capabilities. No evidence or microorganisms were found to support the microbial degradation hypothesis during the course of this study. The degradation of cellulose acetate membranes and other possible causes for membrane failure were discussed.