剩余污泥微生物发酵合成微生物油脂制备生物柴油技术研究

提高剩余污泥微生物发酵合成微生物油脂的含量是促进剩余污泥制备生物柴油技术的重要研究方向.本研究首先比较了BD法、二甲亚砜-甲醇法和酸热法对剩余污泥微生物油脂提取率的影响.结果发现,酸热法提取得到的微生物油脂含量最高,进一步甲酯化合成的生物柴油产率最高达到2.1%.通过控制发酵过程pH和调节初始C/N,可以提高剩余污泥微生物发酵合成可酯化油脂的含量,在pH=4、C/N=100条件下发酵合成的微生物油脂甲酯化得到的生物柴油产量和产率可提高至1.81 g·L~(-1)和13.06%.在此基础上重点比较了4种模拟含糖废水对剩余污泥微生物发酵合成油脂的影响.结果表明,木糖为碳源时合成的微生物油脂进一步甲酯化为生物柴油的产量和产率显著高于乳糖、蔗糖和葡萄糖,分别达到3.90 g·L~(-1)和24.55%.研究表明,以剩余污泥微生物为菌源,采用木糖等含糖废水为培养基,通过控制发酵条件可以强化剩余污泥微生物合成可酯化的微生物油脂含量,进而提高生物柴油产量.

Enhancement of lipid production by fermentation of waste activated sludge for synthesis of biodiesel

It is essential to enhance the yield of saponifiable lipid produced by microorganisms from waste activated sludge (WAS) aiming to improve the industrilization of biodiesel production. In this study, three commonly used lipid extraction methods were compared on their efficiency in lipid extraction. Compared with the other two methods, acid-heating extraction exhibited higher extraction efficiency of lipid, and produced higher biodiesel content at 2.1%. It was efficient to increase the content of saponifiable lipid by controlling pH during fermentation process and adjusting the initial C/N of the media. Under the condition of pH=4 and C/N=100, the biodiesel yield and biodiesel content increased to 1.81 g·L^-1 and 13.06%, respectively. Based on the results, four model sacchariferous wastewaters were used as carbon source to compare their effect on saponifiable lipid accumulation of microorganisms from WAS. Results show that the highest biodiesel yield (3.90 g·L^-1) and content (24.55%) were achieved when xylose was used as carbon source, followed by lactose, sucrose and glucose. This study suggests that it is feasible to use sacchariferous wastewater as media to cultivate the microorganisms of WAS under controlled fermentation conditions to enhance the saponifiable lipid, which can be synthesized for biodiesel.