Simulation of bacterial regrowth in water networks by modelling of Pseudomonas fluorescens growth in a batch and lab biofilm reactor

Bacterial regrowth is causing drinking water deterioration in the distribution networks. The mathematical models could be used to select strategies for combating this problem. Here we present lab-scale experiments where the mathematical model by Zhang et al. (2004) was verified in strictly controlled conditions using Pseudomonas fluorescens. Experiments were performed in a batch and in a perfectly mixed biofilm reactor. The biomass in water and in biofilm was measured with total bacterial counts. Acetate was used as only organic substrate and it was measured as the biologically degradable organic carbon or assimilable organic carbon. The results showed that using maximum specific growth rate, yield, Monod half satura-tion coefficient from batch experiments in the model the biofilm growth was apparently similar however failed statistical Student t-test. In the model bacterial regrowth reached the plateau later than it was observed in experiments. Simulation by adjusting growth coefficients increased the fit however statistically significant similarity between model and experimental data were not reached.