乙醇发酵与渗透汽化在硅橡胶膜生物反应器中的耦合强化

Enhancements of Fermentation and Pervaporation in a Coupling Silicone Rubber Membrane Bioreactor

用硅橡胶膜生物反应器(SMBR)实验研究了发酵-渗透汽化的耦合性能.发酵微生物采用酿酒活性干酵母,所用的碳源为工业级葡萄糖.间歇发酵过程由于产物抑制作用在乙醇浓度达到90g.L-1时就趋于停滞,而经耦合渗透汽化膜分离后,发酵罐内的乙醇浓度迅速降低并维持在40g.L-1,且发酵在此浓度下可以连续稳定地进行.在SMBR运行达到稳态后,乙醇的体积产率为1.5g.L-1.h-1.SMBR中所用的聚二甲基硅氧烷(PDMS)复合膜由实验室自行制备,它能稳定分离含有酵母细胞的发酵液.当发酵液中乙醇浓度为92.7～49.5g.L-1时,PDMS复合膜的总通量为1490～1164g.m-2.h-1,分离因子为6.9～7.8,与分离相同进料浓度的清洁模型溶液相比分别平均高出31%和14%.乙醇发酵和渗透汽化在硅橡胶膜生物反应器中能够相互耦合并得到强化.

Performance of fermentation and pervaporation in a coupling Silicon Rubber Membrane Bioreactor (SMBR) was experimentally studied. The microorganism was Alcohol Instant Active Dry Yeast and the carbon source substrate was glucose of technical grade. Because of product inhibition, batch fermentation tended to suspend when accumulated ethanol concentration in fermenter climbed to 90gL-1. With coupling of pervaporation, ethanol concentration decreased quickly to a constant value of 40gL-1 at which fermentation could proceed continuously. Ethanol productivity of 1.5gL-1h-1 was achieved after SMBR reached a steady state. The composite polydimethylsiloxane (PDMS) membrane in the SMBR was prepared in our laboratory. It separated ethanol from actual fermentation broth efficiently. When ethanol concentration in fermentation broth changed from 92.7 to 49.5gL-1, total flux and selectivity resulted from the PDMS membrane were 1490~1164gm-2h-1 and 6.9~7.8. On average total flux and selectivity for fermentation broth increased by 31% and 14% compared with values for model solution under similar experimental conditions. Fermentation and pervaporation could be well coupled and enhanced each other in the Silicon Rubber Membrane Bioreactor.