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Sediment Entrainment and Flocculation Mediated by Microbial Produced Extracellular Polymeric Substances (EPS)

Author(s): Moritz Thom; Holger Schmidt; Silke Wieprecht; Sabine U. Gerbersdorf

Linked Author(s): Silke Wieprecht

Keywords: No Keywords

Abstract: The stabilizing effects of natural biofilm on erosional processes have been increasingly recognized in the last decades. In riverine systems these effects not only influence sediment dynamics, but also the remobilization of pollutants. Due to the complex interaction between the biofilm, sediment, and hydraulics, an interdisciplinary approach is of great importance. To investigate the erosional processes of fine sediments due to the impacts of naturally grown biofilm, novel flumes are developed and described. The experimental setup consists of a straight glass flume, with adjustable bottom shear stresses. The biofilm is grown on glass beads (diameter: 40–70μm) in the test section of the flume using suspended cells as an inoculum from natural stream water and an artificial nutrient supply. To simulate different growth conditions the setup additionally contains adjustable illumination and a water temperature control system. Biofilm consists of microbes and their metabolic products, the “extracellular polymeric substances (EPS)” . The EPS is often referred to as the “glue” which sticks the cells and the sediment together, thus providing stability. In the growth phase, the adhesive forces are measured using a magnetic particle induction device (MagP I) which will be validated against critical shear stresses. The critical shear stress of the sediment stabilized by fully grown biofilm is determined by applying increasing bottom shear stresses with the SETEG flume. Hydraulic and biologic models still lack a suitable implementationofparametersdescribingthe interrelationship between these two fields. Moreover, the remobilization of pollutants, biologically bound in biofilm, is a focus of future research. This amongst others, emphasizes the importance of an interdisciplinary research approach.


Year: 2012

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