State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China ; Graduate University of Chinese Academy of Sciences, Beijing 100190, China.
Biotechnol Biofuels. 2014 Apr 8;7:53. doi: 10.1186/1754-6834-7-53. eCollection 2014.
Bioethanol production from biomass is becoming a hot topic internationally. Traditional static solid state fermentation (TS-SSF) for bioethanol production is similar to the traditional method of intermittent operation. The main problems of its large-scale intensive production are the low efficiency of mass and heat transfer and the high ethanol inhibition effect. In order to achieve continuous production and high conversion efficiency, gas stripping solid state fermentation (GS-SSF) for bioethanol production from sweet sorghum stalk (SSS) was systematically investigated in the present study.
TS-SSF and GS-SSF were conducted and evaluated based on different SSS particle thicknesses under identical conditions. The ethanol yield reached 22.7 g/100 g dry SSS during GS-SSF, which was obviously higher than that during TS-SSF. The optimal initial gas stripping time, gas stripping temperature, fermentation time, and particle thickness of GS-SSF were 10 h, 35°C, 28 h, and 0.15 cm, respectively, and the corresponding ethanol stripping efficiency was 77.5%. The ethanol yield apparently increased by 30% with the particle thickness decreasing from 0.4 cm to 0.05 cm during GS-SSF. Meanwhile, the ethanol yield increased by 6% to 10% during GS-SSF compared with that during TS-SSF under the same particle thickness. The results revealed that gas stripping removed the ethanol inhibition effect and improved the mass and heat transfer efficiency, and hence strongly enhanced the solid state fermentation (SSF) performance of SSS. GS-SSF also eliminated the need for separate reactors and further simplified the bioethanol production process from SSS. As a result, a continuous conversion process of SSS and online separation of bioethanol were achieved by GS-SSF.
SSF coupled with gas stripping meet the requirements of high yield and efficient industrial bioethanol production. It should be a novel bioconversion process for bioethanol production from SSS biomass.
生物乙醇的生物质生产在国际上成为热门话题。传统的固态发酵（TS-SSF）用于生物乙醇生产类似于传统的间歇操作方法。其大规模强化生产的主要问题是质量和热量传递效率低，以及乙醇抑制作用高。为了实现连续生产和高转化率效率，本研究系统地研究了用于甜高粱秸秆（SSS）的气体吹扫固态发酵（GS-SSF）生产生物乙醇。
在相同条件下，基于不同的 SSS 颗粒厚度进行了 TS-SSF 和 GS-SSF，并进行了评估。GS-SSF 中的乙醇得率达到 22.7 g/100 g 干 SSS，明显高于 TS-SSF。GS-SSF 的最佳初始气体吹扫时间、气体吹扫温度、发酵时间和颗粒厚度分别为 10 h、35°C、28 h 和 0.15 cm，对应的乙醇吹扫效率为 77.5%。在 GS-SSF 中，当颗粒厚度从 0.4 cm 降低到 0.05 cm 时，乙醇得率明显增加了 30%。同时，在相同颗粒厚度下，GS-SSF 的乙醇得率比 TS-SSF 提高了 6%至 10%。结果表明，气体吹扫去除了乙醇抑制作用，提高了质量和热量传递效率，从而大大增强了 SSS 的固态发酵（SSF）性能。GS-SSF 还省去了单独的反应器，进一步简化了 SSS 生物乙醇生产工艺。因此，通过 GS-SSF 实现了 SSS 的连续转化过程和生物乙醇的在线分离。
SSF 与气体吹扫相结合满足高产率和高效工业生物乙醇生产的要求。它应该是一种从 SSS 生物质生产生物乙醇的新型生物转化过程。
