A New Approach in Modelling the Flocs from Biological Wastewater Treatment Bioreactors
Authored by Vasile Lavric, Alexandru Rares Popescu
Date Published: 2010
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Mathematical description
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Abstract
We present a new hybrid technique aimed to model the floc formation, growth and divers distribution. Our approach is adapted from individual
based modeling concepts, using the notion of fundamental building bloc -
the grid cell, defined as the lowest volume/surface of the grid
enclosing the nascent floc for which the continuum properties are still
valid, like concentration of microorganisms, ordinary diffusion etc.
Then the available and forbidden vicinities are used to guide the growth
of microorganisms in clusters (contiguous building blocks). They expand
single free vicinity by single free vicinity as they grow, the next
location being randomly selected among all the available vicinities.
Attachment is another asset of the model - at a given time interval, whose length depends upon the velocity field of the environment, a
fundamental building block comes from the environment and gets fixed to
the outskirts of the nascent floc. These simple steps are combined with
the mass balance equations for the substrates present in the system and
the kinetics describing the biological process. The model is capable of
qualitatively reproducing the cross section distribution of flocs, as
observed through FISH imagery.
Tags
Simulation
bacteria
Detachment
Biofilm model
Nitrification
Dissolved-oxygen
Activated-sludge flocs