Modeling of industrial-scale anaerobic solid-state fermentation for Chinese liquor production
Jin, Guangyuan ; Uhl, Philipp ; Zhu, Yang ; Wijffels, René H. ; Xu, Yan ; Rinzema, Arjen - \ 2020
Chemical Engineering Journal 394 (2020). - ISSN 1385-8947
Chinese liquor - Heat transfer - Mathematical modeling - Product inhibition - Solid-state fermentation - Temperature modeling
Traditional solid-state fermentation processes can give fluctuating product quality and quantity due to difficulties in control and scale up. This paper describes an engineering study of an industrial-scale anaerobic solid-state fermentation process for Chinese liquor (Baijiu) production, aimed at better understanding of the traditional process, as an initial step for future optimization. This mixed-culture fermentation is done in 0.44-m3 vessels embedded in the soil. At this scale, the fermentation is limited by product inhibition. We developed mathematical models based on the Han-Levenspiel equation for product inhibition, with parameters derived from measured data. The models accurately predicted the concentrations of starch and dry matter. A model with radial conduction into a small soil volume around the fermenter and consecutive vertical conduction into the underlying soil accurately predicted the pit temperature in the heating and cooling phases. This model is very sensitive to the values used for the enthalpies of combustion, meaning that direct measurement of the heat production rate would be preferable. In the industry practice, the fermenter volume can be from around 0.20 to 15.00 m3. The model predicts that overheating will occur not only in larger fermenters, but also in the 0.44-m3 fermenters when the soil temperature is high in summer. Our model predictions are consistent with observed behavior in the industry. Our findings can be used to improve this traditional process, as well as similar systems.
Kinetic study of butanol production from various sugars by Clostridium acetobutylicum using a dynamic model
Raganati, Francesca ; Procentese, Alessandra ; Olivieri, Giuseppe ; Götz, Peter ; Salatino, Piero ; Marzocchella, Antonio - \ 2015
Biochemical Engineering Journal 99 (2015). - ISSN 1369-703X - p. 156 - 166.
Biokinetics - Clostridium acetobutylicum - COPASI - Dynamic modelling - Product inhibition - Substrate inhibition
This paper presents a kinetic dynamic model of acetone-butanol-ethanol production by Clostridium acetobutylicum DSM 792 developed with the biochemical networks simulator COPASI. This model is an evolution of previous models described in the literature, updated by including various mono-, di-, hexose and pentose sugars: glucose, mannose, fructose, sucrose, lactose, xylose and arabinose. The kinetic relationships of uptake of substrate, butanol production, cell growth and cell death are also included.The batch fermentation tests were carried out at an initial sugar concentration ranging from 5 to 100. g/L. The data from the batch tests were used to assess the kinetic parameters of the model. This model gave satisfactory results for each sugar, both in terms of simulation of fermentation - the square correlation coefficient of metabolite concentrations, calculated by comparing experiments and simulations, ranged between 0.87 and 0.925 - and of comparison with the models reported in the literature.The effects of mono-, di-, hexose and pentose sugars on the growth and production of metabolites, including acids and solvents, were reviewed according to the proposed model. The low fermentation performance measured for xylose and lactose were interpreted taking into account the sugar uptake, the acid production and the hydrolysis path.