Startup and Steady State in a Chemostat

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This Demonstration shows the operation of a chemostat. Starting up as a batch reactor, the concentrations change with time. After this short transient period, the bioreactor settles into a steady state.
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Contributed by: R. Ricardo Sánchez (August 2022)
Open content licensed under CC BY-NC-SA
Snapshots
Details
The characteristics of continuous operation are as follows:
Snapshot 1: steady state; after an initial startup period, there is no variation of concentrations with time
Snapshot 2: constant reaction rates, where is the biomass reaction rate,
is the reaction rate of the consumed reactant and
is the product reaction rate
Snapshot 3: Washout of the organisms (cells) will occur when the dilution rate is greater than the specific growth rate
. This corresponds to the complete removal of cells by flow out of the tank. In many references, including [1], the variables
,
,
and productivity
are plotted versus the dilution rate
, which characterizes the steady state in a chemostat. See Related Links.
Some suggestions for the user:
Increase interactively to note effect on washout.
Change the feed substrate concentration to alter the steady state.
Investigate the influence of maintenance requirements on the steady-state biomass concentration.
Operate initially as a batch reactor with , and switch to chemostat operation with
.
is the maximum specific growth rate, and in this case was set up to
.
Calculate , the biomass-substrate yield, making use of the yield graph.
Reference
[1] I. J. Dunn, E. Heinzle, J. Ingham and J. E. Prvenosil, Biological Reaction Engineering: Dynamic Modelling Fundamentals with Simulation Examples, Second Edition, Weinheim, Germany: Wiley-VCH, 2003.
Permanent Citation