Biofouling Studies on Thin Film Composite Membranes for Reverse Osmosis Desalination Processes

Abstract

Membranes are the most sensitive unit to the damaging effect of biofouling in reverse osmosis equipment. Biofouling is defined by many variables and elements, including a surface-deposited organized microbial ecosystem showing complex functional and structural characteristics, known as biofilm. Biofilm formation results from the excretion of an extracellular protective matrix by microorganisms. Biofilm blocks reverse osmosis (RO) membranes, decreasing the permeability and, consequently, the rate at which water can be desalinated. The nutritional and microbial parameters of water samples from the Cortes Sea, and specifically from the coast of Guaymas, Sonora, México, were determined. The water samples were used to isolate marine microorganism present in this ecosystem. A modified growth medium was developed to represent this specific sea environment. Finally, several artificial biofouling-related experiments were carried out in order to reproduce, and then, analyze the potential membrane damage caused by biofouling. A discrepancy was found between the salinity in the water samples from the Guaymas coast and the standard salinity expected for the Pacific Ocean. Several causes for this variability and its effect on the physical and chemical parameters are proposed, and the potential impact on desalination plants due to the microbial population, which will ultimately be responsible for biofouling on RO membranes, is analyzed.

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