Biofilm Reduction Modelling in a Drip-flow Reactor. Developing a Method for Growing Biofilms in a Laboratory Setting, to Evaluate the Effects of an Anti-fouling Product Used in Paper Machines.

Abstract

Bacterial biofilms naturally form in paper machines, causing problems in production. Reducing the amount of biofilm formed is therefore of interest to the paper industry. To model biofilm reduction, a method was developed for growing biofilms in a laboratory setting at BIM Kemi Sweden AB. The goal was for the method to be used to evaluate effect of the anti-fouling product Bimogard produced by the company, a non-biocidal agent that reduces formation of process disrupting biofilms in paper machines. Initial experiments were carried out using petri dishes for cultivation, but the main part of the work was carried out using a drip-flow biofilm reactor. The biofilms were quantified by staining with safranin and measuring absorbance. Different process parameters for running the reactor were examined and improved, including what medium concentration to use and whether to inoculate with a mono-culutre of Pseudomonas fluorescens or a co-culture where Bacillus subtilis was also added. The final method, using the mono-culture and 7.5% of standard medium concentration, was used to evaluate the effects of adding Bimogard to the nutrient medium. The addition of Bimogard significantly reduced the amount of biofilm formed, but only at low concentrations.