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dc.contributor.authorBeyenal, Haluk
dc.contributor.authorLewandowski, Zbigniew
dc.date.accessioned2017-08-21T20:55:13Z
dc.date.available2017-08-21T20:55:13Z
dc.date.issued2002-02
dc.identifier.citationBeyenal, H. and Z. Lewandowski, "Internal and external mass transfer in biofilms grown at various flow velocities," Biotechnol. Prog., 18:55-61 (2002).en_US
dc.identifier.issn8756-7938
dc.identifier.urihttps://scholarworks.montana.edu/xmlui/handle/1/13566
dc.description.abstractIt appears that biofilms arrange their internal structure according to the flow velocity at which they are grown, which affects the internal mass transfer rate and microbial activity. In biofilms grown at various flow velocities we determined the vertical profiles of the local relative effective diffusivity (termed Dsa) at several locations within each biofilm. From these profiles we calculated the surface-averaged relative effective diffusivity (termed D1) at various distances from the bottom and plotted it against these distances. The Dsa decreased linearly toward the bottom, forming well-defined profiles that were different for each biofilm. The gradients of these profiles were multiplied by the diffusivity of oxygen, ζ= Dw dDa/dz, and plotted versus the flow velocity at which each each biofilm was grown. The gradients were low at flow velocities below 10 cm/s, reached a maximum at a flow velocity of 10 cm/s, and decreased again at flow velocities exceeding 10 cm/s. The existence of a maximum indicates a possibility that two opposing forces were affecting the slope of the profiles. To explain these observations we hypothesized that biofilms, depending on the flow velocity at which they are grown, arrange their internal architecture to control (1) the nutrient transport rate and (2) the mechanical pliability needed to resist the shear stress of the water flowing past them. It appears that biofilms attempt to satisfy the second goal first, to increase their mechanical strength, and that they do so at the expense of the nutrient transfer rate to deeper layers. This strength increase is associated with an increase in biofilm density, which slows down the internal mass transport rate. Biofilms grown at low flow velocities exhibit low density and high effective diffusivity but cannnot resist higher shear stress, whereas biofilms grown at higher flow velocities are denser and can resist higher shear stress but have a lower effective diffusivity.en_US
dc.titleInternal and external mass transfer in biofilms grown at various flow velocitiesen_US
dc.typeArticleen_US
mus.citation.extentfirstpage55en_US
mus.citation.extentlastpage61en_US
mus.citation.issue1en_US
mus.citation.journaltitleBiotechnology Progressen_US
mus.citation.volume18en_US
mus.identifier.categoryEngineering & Computer Scienceen_US
mus.identifier.doi10.1021/bp010129sen_US
mus.relation.collegeCollege of Engineeringen_US
mus.relation.departmentCenter for Biofilm Engineering.en_US
mus.relation.departmentChemical & Biological Engineering.en_US
mus.relation.departmentChemical Engineering.en_US
mus.relation.universityMontana State University - Bozemanen_US
mus.relation.researchgroupCenter for Biofilm Engineering.en_US
mus.data.thumbpage2en_US


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