Program One
Thursday, May 22, 1997

Biofilms and Barriers Kansa A



Z. Lewandowski, Center for Biofilm Engineering, Montana State University. Bozeman, MT 59717 Particle Image Velocimetry in conjunction with the Confocal Scanning Laser Microscope and Magnetic Resonance Imaging provided detailed images of flow within the interstitial voids of heterogenous biofilms. Water could freely move along the channels within the biofilm inducing the convective mass transfer of dissolved and particulate substrates. The measurements demonstrated the existence of a dual flow field near the biofilm surface. The two flow fields, one above and one below the biofilm surface, influence each other in a complex way.

Spatial distribution of local mass transfer co-efficient above and within biofilms was measured using a microsensor based on limiting current technique. The mass transfer coefficients measured within microbial clusters and within interstitial voids were significantly different. Measurement of local flow velocities near the microsensor's tip using Particle Image Velocimetry in conjunction with the Confocal Scanning Laser Microscope permitted us to quantify the relation between the hydrodynamics, and mass transfer coefficient at specific locations above and within the biofilm.

It is becoming apparent that mass transport within biofilms is much more complex than previously assumed as 1 ) the biofilm itself is heterogenous and consists of discrete cell clusters separated by interstitial voids; 2) the hydrodynamics in the biofilm region is controlled by two flow fields; and 3) the mass transfer coefficient behaves unexpectedly in the biofilm. Although the newly proposed concept of biofilm structure helps to interpret the experimental observations, the new experiments reveal further dimensions of complexity.

We are becoming progressively aware that it may not be possible to completely describe mass transport in biofilm systems mathematically. Some simplifying assumptions are, therefore, urgently needed to establish empirical equations serving purely practical purposes. It is important that these assumptions are established as a result of careful experimentation rather than convenience.

Key words: biofilm, biofilm structure, biofilm activity,

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Tuesday, May 20, 1997

Metals Kansa A

Remediation of Munitions Compounds Kansa B

Analytical Methods Kansa C/D

General Topics Kansa B

Wednesday, May 21, 1997

Metals Kansa A

Zero-Valent Metals Kansa A

Remediation Kansa A

Vegetation-based Remediation Kansa B

Partnerships & Innovative Technologies Kansa C/D

Nonaqueous Phase Liquids Kansa C/D

Thursday, May 22, 1997

Biofilms & Barriers Kansa A

Bioremediation Kansa B

Partnerships & Technology Innovations Kansa C/D

Remediation Kansa C/D


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