Computer
applications in fermentation technology
The
use of computers for control of fermentation process has increased
significantly in the last decade. It is being used for both industrial
fermentation and fermentation research. A computer can be a vital
instrument for process optimization and control. The first project to computerize
a fermentation began in 1966 in England when direct digital control for the
control of temperature, pH, air flow and form level were done in a production
fermentation vessel.
For
a fermentation production plant the primary objective of computer control is to
produce a product as economically as possible. The computer is generally
used to provide quality control, to save the operational time, to furnish
automatic documentation and to decrease the per loop control cost.
The
basis of any system used in monitoring and controlling a fermentation process
is instrumentation. Both computer
hardware and software are required for control of fermentation process to
measure and control the process variables which may be either environmental parameter
or physiological parameter or based on the Biomass. Common environmental variables are
temperature, pH, dissolved oxygen, agitation speed, aeration rate and nutrient
concentration. Physiological variables
are the products of metabolism and variables describing the state of metabolism.
The
variables to be measured may be directly measured using a sensor. For the variables which are not directly measurable
gateway sensors are used. In this
technique the non-measurable parameter is extracted from a combination of
measurable parameters. The use of
computer is very useful in making this type of variable measurements.
Three
distinct areas of computer function in fermentation are:
1.
Logging of process data. Data logging is performed by the data
acquisition system which has both hardware and software components. There is an
interface between the sensors and the computer. The software should include the
computer program for sequential sensor signals and the procedure of data
2.
Data analysis (Reduction of logged data) : Data reduction
is performed by the data analysis system, which is a computer program based on
a series of selected mathematical equations.
The analysed information may then be put on a print out, fed into a data
bank or utilized for process control.
3. Process control. Process control is also performed using a computer program. Signals from the computer are fed to pumps, valves or switches via the interface. In addition the computer proggram may contain instructions to display devices, to indicate alarms, etc.
The interfacing techniques used in coupling the computer with measurement and control in a fermentation process includes the following basic components. There will be modules providing analogue inputs, analogue outputs, digital inputs, digital outputs and interrupt inputs.
The computer applications in
fermentation Technology are used in the automation in penicillin fermentation,
fermentative production of enzymes, for fault analysis during fermentation to
monitor product losses and also for fermentation research.
There are two distinct fundamental approaches to computer control of fermenters. The first is when the fermenter is under the direct control of the computer software. This is termed Direct Digital Control (DDC). The second approach involves the use of independent controllers to all control functions of a fermenter and the computer communicates with the controller only to exchange information. This is termed Supervisory Set-Point Control (SSC).
It is possible to analyse data, compare it with model systems and use control programs which will lead to process optimization. However, process optimization by use of computer is not a widely used procedure in the fermentation industries at present.
References
- Industrial Microbiology, Second Edition, AH Patel, Trinity press
- Principles of fermentation technology, PF Stanbury, A Whittakker, SJ Hall, 1995, Butterworth-Heinemann publications
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