title: Determining the flow regime in a biofilm carrier by means of magnetic resonance imaging.
abstract: Biofilms on cylindrical carrier material originating from a lab-scale moving bed biofilm reactor (MBBR) were investigated by means of Magnetic Resonance Imaging (MRI). The aim of this study was to determine the local flow velocities at the inner face of the biofilm carrier. To get an insight into the mass transport processes, flow velocity maps of blank and with biofilm cultivated carriers were measured. A single carrier was placed in a tube in three different orientations and exposed to flow velocities of 0.21, 0.42, and 0.64 mm/s. The interplay of the biofilm morphology and the local flow pattern was then analyzed including the effect of the orientation of the carrier in relation to the upstream flow angle. Within this study, the biofilm carrier can be understood as an interconnected system of four sections in which the incoming fluid volume will be distributed depending on the biomass occupation and morphology. In sections with high biofilm occupation, the flow resistance is increased. Depending on the orientation of the carrier in the flow field, this effect leads to flow evasion through less covered sections showing higher flow velocities and consequently the risk of biofilm detachment. However, there was no clear correlation between biofilm coverage and flow ratio.
authors.affiliation: Chair of Water Chemistry Water Technology, Karlsruhe Institute of Technology, Engler-Bunte-Ring 1, Karlsruhe, 76131, Germany.
authors.forename: Maria P
authors.initials: MP
authors.lastname: Herrling
authors.forename: Gisela
authors.initials: G
authors.lastname: Guthausen
authors.forename: Michael
authors.initials: M
authors.lastname: Wagner
authors.forename: Susanne
authors.initials: S
authors.lastname: Lackner
authors.forename: Harald
authors.initials: H
authors.lastname: Horn
mesh_terms: D018441:Biofilms; D018533:Biomass; D019149:Bioreactors; D004867:Equipment Design; D008279:Magnetic Resonance Imaging / Q000379:methods*
keywords: biofilm; flow regime; flow velocity; magnetic resonance imaging; morphology; moving bed biofilm reactor