Abstract
Commercial seawater reverse osmosis (SWRO) membranes were coated with iron nanoparticles (FeNPs) and biofouled with a bacterium strain isolated from the Sea of Cortez, Mexico. This strain was selected and characterized, as it was the only cultivable strain in pretreated seawater. Molecular identification of the strain showed that it belongs to Bacillus halotolerans MCC1. This strain was Gram positive with spore production, and was susceptible to Fe+2 toxicity with a minimum inhibitory concentration of 1.8 g L−1. Its biofouling potential on both uncoated and FeNP coated reverse osmosis (RO) membranes was measured via biofilm layer thickness, total cell count, optical density and organic matter. The FeNP-coated RO membrane presented a significant reduction in biofilm cake layer thickness (>90%), total cells (>67%), optical density (>42%) and organic matter (>92%) with respect to an uncoated commercial membrane. Thus, Bacillus halotolerans MCC1 shows great potential to biofoul RO membranes as it can pass through ultrafiltration membranes due to its spore producing ability; nonetheless, FeNP-coated membranes represent a potential alternative to mitigate RO membrane biofouling.
Highlights
Halotolerant bacteria are of great biotechnological importance for industry, as they are easy to grow under limited nutritional requirements
The aim of this paper is to study the effect of FeNP coating of reverse osmosis (RO) membranes on the extent of biofouling caused by bacteria native to the Sea of Cortez
As the ultrafiltration membrane nominal pore size of 0.1 μm is smaller than the typical sizes of bacteria, this indicates membrane nominal pore size of 0.1 μm is smaller than the typical sizes of bacteria, this indicates that that only spores could pass through the filter and grow on the Petri dishes, originating the only spores could pass through the filter and grow on the Petri dishes, originating the colony forming units (CFU)
Summary
Halotolerant bacteria are of great biotechnological importance for industry, as they are easy to grow under limited nutritional requirements. Their tolerance to high salt concentrations minimizes laboratory contamination risks [1]. In India, a halotolerant bacillus has been used for the biosynthesis of enzymes (L-Glutaminase) in bioethanol production [4]. In Algerian wetland ecosystems, a study found that halotolerant strains belonging to the genera Haloferax, Halococcus and Haloarcula showed a high production of molecules with important biotechnological applications, such as in the coastal agriculture, pharmaceutical and environmental fields [5]. In Spain, the dominant halotolerant genera isolated from the Bras del Port salt basins included
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