Department of Energy and Resources Engineering, Peking University, Beijing, China.
J Biosci Bioeng. 2010 Jan;109(1):41-6. doi: 10.1016/j.jbiosc.2009.07.002. Epub 2009 Jul 28.
Waste molasses is one of the most important feedstock for ethanol production in Brazil as well as in many Southeast Asian countries, including China. Sulfuric acid pretreatment is employed in most ethanol distilleries in China to control bacterial contamination, which results in difficulties in the treatment of wastewater containing high levels of sulfate ions. In this study, a high efficiency, non-sterilized, continuous ethanol fermentation process without sulfuric acid pretreatment was developed using the flocculating yeast strain KF-7 and the widely utilized, traditional, stirred tank reactors. An alternative molasses medium feeding method, which differs from traditional methods, is proposed that effectively controls bacterial contamination. Separate feeding of 1.2-fold diluted molasses and tap water into the reactor proved to be effective against bacterial contamination during long-term continuous fermentation. By feeding yeast cells with high metabolic activity to the second reactor, a two-stage continuous fermentation process that yielded a high ethanol concentration of 80 g/l as well as high ethanol productivity of 6.6 g/l/h was successfully operated for more than one month. This fermentation process can be applied to ethanol distilleries in which traditional tank reactors are used.
废糖蜜是巴西乃至包括中国在内的许多东南亚国家生产乙醇的最重要原料之一。硫酸预处理被广泛应用于中国的大多数乙醇蒸馏厂，以控制细菌污染，这导致处理高浓度硫酸盐离子废水变得困难。在这项研究中，使用絮凝酵母菌株 KF-7 和广泛使用的传统搅拌釜反应器，开发了一种无需硫酸预处理的高效、非灭菌、连续乙醇发酵工艺。提出了一种与传统方法不同的替代废糖蜜进料方法，可有效控制细菌污染。向反应器中分别进料 1.2 倍稀释的糖蜜和自来水，被证明在长期连续发酵过程中可有效防止细菌污染。通过向第二反应器中输送高代谢活性的酵母细胞，成功地进行了两段连续发酵，乙醇浓度高达 80 g/L，乙醇生产率高达 6.6 g/L/h，持续运行了一个多月。该发酵工艺可应用于使用传统罐式反应器的乙醇蒸馏厂。
