Schutyser M A I, Briels W J, Boom R M, Rinzema A
Wageningen Centre for Food Sciences, P.O. Box 557, 6700 AN Wageningen, The Netherlands.
Biotechnol Bioeng. 2004 May 20;86(4):405-13. doi: 10.1002/bit.20076.
The development of mathematical models facilitates industrial (large-scale) application of solid-state fermentation (SSF). In this study, a two-phase model of a drum fermentor is developed that consists of a discrete particle model (solid phase) and a continuum model (gas phase). The continuum model describes the distribution of air in the bed injected via an aeration pipe. The discrete particle model describes the solid phase. In previous work, mixing during SSF was predicted with the discrete particle model, although mixing simulations were not carried out in the current work. Heat and mass transfer between the two phases and biomass growth were implemented in the two-phase model. Validation experiments were conducted in a 28-dm3 drum fermentor. In this fermentor, sufficient aeration was provided to control the temperatures near the optimum value for growth during the first 45-50 hours. Several simulations were also conducted for different fermentor scales. Forced aeration via a single pipe in the drum fermentors did not provide homogeneous cooling in the substrate bed. Due to large temperature gradients, biomass yield decreased severely with increasing size of the fermentor. Improvement of air distribution would be required to avoid the need for frequent mixing events, during which growth is hampered. From these results, it was concluded that the two-phase model developed is a powerful tool to investigate design and scale-up of aerated (mixed) SSF fermentors.
数学模型的发展推动了固态发酵（SSF）的工业化（大规模）应用。在本研究中，开发了一种鼓式发酵罐的两相模型，该模型由离散颗粒模型（固相）和连续介质模型（气相）组成。连续介质模型描述了通过曝气管道注入床层中的空气分布。离散颗粒模型描述了固相。在之前的工作中，虽然本研究未进行混合模拟，但已用离散颗粒模型预测了固态发酵过程中的混合情况。在两相模型中实现了两相之间的传热传质以及生物质生长。在一个28立方分米的鼓式发酵罐中进行了验证实验。在该发酵罐中，在前45 - 50小时内提供了充足的曝气，以将温度控制在接近生长最佳值的水平。还针对不同规模的发酵罐进行了多次模拟。鼓式发酵罐中通过单根管道进行强制曝气，无法使底物床层实现均匀冷却。由于温度梯度较大，随着发酵罐尺寸的增加，生物质产量严重下降。需要改进空气分布，以避免频繁进行混合操作，因为混合操作会阻碍生长。从这些结果可以得出结论，所开发的两相模型是研究曝气（混合）固态发酵罐设计和放大的有力工具。
