ISSN:
0006-3592
Keywords:
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Inhibitory substrate levels are common in industrial fermentations and in biological waste-water treatment of many industrial wastes. Continuous microbial cultures are unstable to certain disturbances, such as shock loading by inhibitory substrates. Two feedback proportional control strategies are analyzed and compared for a simple model culture assumed represent able by the culture concentrations of biomass and a single rate-limiting and growth-limiting nutrient (substrate). One control strategy, the well known turbidostat, consists of adjusting culture holding time (e.g., by flow rate adjustment) in response to deviations in turbidity or some other measure of culture biomass concentration. The other control strategy is to adjust holding time in response to deviations in limiting nutrient concentrations in the culture. This second control strategy, termed the nutristat, can be superior to the turbidostat in many applications. The sign and magnitude of the dimensionless group {(X/YD)[dμ/dS]s}, is shown to be an important determinant, in the behavior of the open loop and the two closed loop processes. This characteristic group is positive when the specific growth rate is increased by increases in the nutrient concentration, zero when the growth rate is unaffected by the nutrient concentration, and negative in the presence of nutrient or substrate inhibition.The effects of process modifications and of modeling assumptions on the control of the process are discussed and more sophisticated control schemes are also proposed.
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bit.260140606
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