Center for Biofilm Engineering
Abstract:
"Biofilm Structure and Influence on Biofouling under Laminar and
Turbulent Flows"
99-035 A flow system was designed so that biofilms
could be grown simultaneously in parallel flow cells under laminar and turbulent
flows using shared nutrients and inocula. The flow cells were made from
rectangular glass tubing chosen to simulate flow in industrial pipes. The
hydrodynamics in the flow cells were characterized using dye tracers and the
relationship between the Fanning friction factor (f) and Reynolds number
(Re). Flow was laminar at Re 100 and turbulent at Re 3000. Transition between
flows occurred at approximately Re 1000. Biofilms from environmental inocula
were grown on tap water or a minimal salts medium with 40 ppm glucose. Biofilms
grown under laminar flow were patchy and consisted of cell clusters separated by
interstitial voids. Biofilms grown under turbulent flow were filamentous. The
filaments had a complex structure and were formed by the colonization of
filamentous sheathed bacteria with microcolonies of non-filamentous bacteria.
The filamentous bacteria were often tangled together and subsequent colonization
by microcolonies resulted in the formation of cohesive structures that we termed
“biofilm streamers”. The frictional loss coefficient (kf) across the
flow cell colonized with biofilm grown under turbulent flow was almost twice the
kf across the flow cell colonized with biofilm grown under laminar flow. There
was little difference in kf across the flow cell colonized with biofilm grown
under laminar flow and the kf across a clean flow cell.
Stoodley, P., J. Boyle, A.B. Cunningham, I. Dodds, H.M.Lappin-Scott, and Z.
Lewandowski. 1999. Biofilm Structure and Influence on Biofouling under Laminar
and Turbulent Flows," In: Biofilms in the Aquatic Environment, pp.
13-24, Edited by C.W. Keevil, A. Godfree, D. Holt, C. Dow. The Royal Society of
Chemistry Press, Cambridge.
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