Biofilms – From the mouth to water treatment plants
When bacteria are under stress, they team up and form this collective called a biofilm. Naturally occurring biofilms have a very complicated network. They are like cities with channels for nutrients to go in and waste to go out. Medically, bacterial biofilms are responsible for several chronic diseases, including endocarditis, cystitis and infections caused by indwelling medical devices. The BIOFILMS AND FLOW (An integrative study on the distribution, morphology and composition of biofilms under the influence of secondary flows around flow obstructions) research project looked at biofilms from an industrial viewpoint. Researchers worked on the details of distribution, morphology and composition of biofilms, looking at applications such as those in wastewater treatment systems. Project researchers developed a model to describe the development and growth of a biofilm in a large-scale reverse osmosis desalination system. The model accounts for bio-growth in the presence of nutrients, its effect on mass transfer and its interplay with hydrodynamics in the membrane channels. It also provides a tool for assessing conditions leading to an increased resistance to permeation versus channel clogging. Both factors are of paramount importance in the energy efficiency of real operation. BIOFILMS AND FLOW also investigated deformation of a bacterial cell and showed that this may either increase deposition or impede it, depending on the length scales where the competing forces act. One implication of this model is that it enables the identification of sustainable operating conditions for the membrane. Furthermore, design should incorporate increased repulsive forces close to the membrane surface. Research results have provided important new knowledge on the fundamental aspects of bacterial deposition. Looking to the future, experimental design and fabrication of spacers should continue. Additionally, bio-growth will be monitored, as published studies suggest that biofilms are easy to remove from such surfaces. This constitutes an exciting future prospect.
Keywords
Biofilm, water treatment, reverse osmosis, desalination, membrane