Modeling Biological and Chemical Processes in Slow Sand Filtration
Dr. Michael Misovich, Hope College
The goal of this project was to quantitatively model biological and chemical processes in Manz intermittently operated biosand water filters. Velocity within filter zones was successfully modeled by the Kozeny-Carman packed bed flow equation, accounting for resistance and permeability. Biological and chemical process models focused on steady-state cell growth, using the Monod equation with stoichiometric yield coefficients describing consumption of nutrients and oxygen and production of waste products. Difficulties were encountered in finding appropriate values of model parameters, since most biochemical process models focus on conversion of substrate to product at relatively high concentrations, whereas models for drinking water systems focus on addition of chemicals to minimize microorganism growth. Future work will include better estimation of model parameters, modeling of diffusion phenomena and of the biolayer as a separate phase, and unsteady-state modeling of intermittent operation used in practice.
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