Garrido-Vidal Diego, Pizarro Consuelo, González-Sáiz José M
Chemical Engineering, Department of Chemistry, University of La Rioja, C/ Madre de Dios 51, 26006 Logroño, La Rioja, Spain.
Biotechnol Prog. 2003 Sep-Oct;19(5):1468-79. doi: 10.1021/bp034055r.
The modeling and optimization of industrial processes requires an intensive study of the factors involved. In this work, a continuous pilot system for studying the industrial process of acetic fermentation is developed. A Doehlert design is applied to the five variables involved in the pilot process. This experimental design allows reduction of the experimental burden and the maximum amount of information to be obtained, studying the factors at different levels depending on their significance. The experimental system provides a robust measure of the specific growth rate and the rates of substrates consumption and acetic acid production, related to the flow of effluent stream evaluated in the steady state. The results demonstrate the growth-associated kinetics of substrates and product, and the yield factors are calculated with low values of variances for the coefficients, i.e., within the range 1-11%. The specific growth rate suits the quadratic model proposed. The response surfaces generated by the model are applied to explain the behavior of the bacterial growth and, therefore, the effects of the process variables studied over the acetic acid production. Very low levels of ethanol or oxygen make the acetification rate decrease, and a saturation effect with high levels of ethanol or oxygen is also deduced. The effects of the aeration rate, agitation, and overpressure suggest a kind of inhibition of the acetic acid production caused by the oxygen that has not been practically studied before. The temperature strengthens the inhibitory effect of the ethanol and the oxygen. The conclusions of this work consolidate the structure of a hybrid model for the acetic fermentation.
工业过程的建模与优化需要深入研究其中涉及的各种因素。在本研究中，开发了一个用于研究醋酸发酵工业过程的连续中试系统。将Doehlert设计应用于中试过程中涉及的五个变量。这种实验设计能够减轻实验负担并获取最大信息量，根据因素的重要性在不同水平上对其进行研究。该实验系统能可靠地测量特定生长速率以及底物消耗速率和醋酸生成速率，这些速率与稳态下评估的流出物流流量相关。结果表明了底物和产物的生长关联动力学，并且计算出的产率因子系数方差值较低，即在1 - 11%的范围内。特定生长速率符合所提出的二次模型。由该模型生成的响应面用于解释细菌生长行为，进而解释所研究的过程变量对醋酸生产的影响。极低水平的乙醇或氧气会使醋酸化速率降低，并且还推断出高水平的乙醇或氧气存在饱和效应。通气速率、搅拌和超压的影响表明存在一种此前实际未研究过的由氧气导致的对醋酸生产的抑制作用。温度增强了乙醇和氧气的抑制作用。本研究的结论巩固了醋酸发酵混合模型的结构。
