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Diffusion and reaction within porous packing media: A phenomenological model
Author(s) -
Jones Warren L.,
Dockery Jack D.,
Vogel Curtis R.,
Sturman Paul J.
Publication year - 1993
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260411005
Subject(s) - pellets , mass transfer , residence time distribution , diffusion , pellet , chemistry , biomass (ecology) , chemical engineering , substrate (aquarium) , steady state (chemistry) , porous medium , porosity , materials science , chromatography , thermodynamics , mineralogy , composite material , organic chemistry , geology , inclusion (mineral) , physics , oceanography , engineering
A phenomenological model has been developed to describe biomass distribution and substrate depletion in porous diatomaceous earth (DE) pellets colonized by Pseudomonas aeruginosa. The essential features of the model are diffusion, attachment and detachment to/from pore walls of the biomass, diffusion of substrate within the pellet, and external mass transfer of both substrate and biomass in the bulk fluid of a packed bed containing the pellets. A bench‐scale reactor filled with DE pellets was inoculated with P. aeruginosa and operated in plug flow without recycle using a feed containing glucose as the limiting nutrient. Steady‐state effluent glucose concentrations were measured at various residence times, and biomass distribution within the pellet was measured at the lowest residence time. In the model, microorganism/substrate kinetics and mass transfer characteristics were predicted from the literature. Only the attachment and detachment parameters were treated as unknowns, and were determined by fitting biomass distribution data within the pellets to the mathematical model. The rate‐limiting step in substrate conversion was determined to be internal mass transfer resistance; external mass transfer resistance and microbial kinetic limitations were found to be nearly negligible. Only the outer 5% of the pellets contributed to substrate conversion. © 1993 Wiley & Sons, Inc.