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Institut für Wasser- und Umweltsystemmodellierung - IWS



"Das MagPI IP System: Eine Versuchsreihe zu teilautomatisierten Adhäsionsmessungen auf Biofilmen und Datenanalyse mittels Matlab"

The aim of this study is to prove the accuracy of the semi-automated method of the Magnetic Particle Induction - Image Processing (MagPI-IP), which is a further development of the Magnetic Particle Induction (MagPI). The further issue of the present study is to measure the influence of flow velocity on biofilm adhesion by using MagPI-IP. MagPI-IP measurements on six different surfaces, which offered non-adhesive or adhesive properties, were repeated to examine the accuracy of the method.
It could be shown that standard deviations are very small (< 5%) regarding to measurements on the non-adhesive surface, which implicates a high accuracy of MagPI-IP at measuring non-adhesive surfaces. The measurements on the adhesive surfaces showed considerably higher standard deviations, which implicates that the accuracy of MagPI-IP is lower at adhesive surfaces.
In order to get natural biofilms, water from the river Enz was gathered. Six gutters each containing 16 biofilm-cardridges were constructed at the experimental hall of the Institut für Wasser- und Umweltmodellierung of the Universität Stuttgart. The flow velosity in each gutter had been varied systematically. Due to the first flow velocity change the biofilm adhesion showed to get higher (up to 38%), if biofilms experienced an increase of flow velocity compared to biofilms, which are grown at a stable low flow velocity. Biofilms, which experienced an increase of flow velocity responded to the second increase of flow velocity with a quicker adaption and an overall higher adhesion, compared to biofilms, which experienced only one increase in flow velocity. However reduction of flow velocity leaded to increases of biofilm adhesion (up to 29%).
The results of this study show that the semi-automated MagPI-IP method for measuring adhesion of surfaces still requires further investigation and also that changes in flow velocity have a major impact on biofilm adhesion.