Interaction of Colloidal Fe/Mn Oxides Concentration and Shear Stress on Biofilm Formation

Abstract

Six test runs were carried out to explore the interaction of shear stress and Fe/Mn oxides concentration on the growth of heterotrophic micro-organisms in biofilms. Experimental results revealed that the existence of Fe/Mn colloids was beneficial to biofilm formation. Significant interactions existed (p < 0.001) between shear stress and influent Fe/Mn concentration on biofilm bacteria growth and dissolved organic carbon consumption. Biofilm bacteria numbers were positively related to the dissolved organic carbon consumption rate. This implies that the influent Fe/Mn concentration did not interfere with the uptake of the carbon source by biofilm bacteria. At a higher Fe/Mn concentration (HCS), the biofilm HPC number significantly increased with an increase in shear stress. However, the opposite relation was found at a lower Fe/Mn concentration (LCS). A significant interaction existed between influent colloidal Fe/Mn concentration and shear stress on the kinetic and yield parameters specific growth rate (μb), specific substrate utilization rate (q), and observed growth yield (γobs). The size distribution of particles based on particle concentration (No · ml−1) was also examined in the study.