Microbial Biofouling: A Mechanistic Investigation

Microbial biofouling is important in a variety of applications including reverse osmosis membranes and in-situ bioremediation. The initial microbial adhesion plays the key role in microbial biofouling on abiotic surfaces, which can be explained in terms of microbial surface properties. This research investigated the interactions of three indigenous bacteria with the porous medium of silica sand and their corresponding initial attachment. Traditional and extended DLVO forces were calculated based on independently measured bacterial and medium surface thermodynamic properties and were related to bacterial attachment observations. Lifshitz–van der Waals, electrostatic and Lewis acid/base forces were found to be strongly dependent on the separation distance between bacteria and the medium surface. It was concluded that the electrostatic force served as the barrier preventing the bacterial strains from getting close to the medium. Once the bacterial strains overcame the barrier with the aid of hydrodynamic forces, Lifshitz–van der Waals force and electrostatic force dropped while Lewis acid/base force increased with the decrease of separation distance. Consequently, Lewis acid/base force became the dominating force controlling bacterial adhesion.