Predicting bed expansion and phase holdups for three-phase fluidized-bed reactors with and without biofilm

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39 Scopus citations


A predictive model is developed for the hydraulic behavior, such as bad height and overall gas, liquid, and solid holdups (volume fractions), of three-phase fluidized-bed reactors. The model uses process parameters, such as reactor dimensions, particle properties, and gas and liquid flowrates, as input variables. A wake model is applied to predict the liquid holdup, while the solids holdup is obtained by iteration based on material balance. Experimental results to evaluate the three-phase fluidization model are obtained from a laboratory-scale reactor using two sizes of clean glass beads under wide range of gas and liquid velocities. Modeling predictions and experimental results agree quantitatively for two-phase and three-phase conditions. The model is further applied to analyze fluidized beds with biofilm-coated media. Biofilm accumulation alters the drag coefficient (CD) and bed expansion index (n). Applying a modified correlation for CD to biofilm systems found in literature, the authors propose a new correlation for n which shows little dependence on the particle terminal Reynolds number.

Original languageEnglish (US)
Pages (from-to)2604-2616
Number of pages13
JournalWater Research
Issue number10
StatePublished - Oct 1997
Externally publishedYes


  • Biofilm reactors
  • Fluidized bed
  • Hydrodynamics
  • Modeling
  • Phase holdup
  • Three-phase
  • Wake theory

ASJC Scopus subject areas

  • Water Science and Technology
  • Ecological Modeling
  • Pollution
  • Waste Management and Disposal
  • Environmental Engineering
  • Civil and Structural Engineering


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