含糖废水颗粒污泥制备生物柴油的机制研究及方法开发

Biodiesel, fatty acid methyl esters (FAMEs), has grabbed great attention due to the advantages such as; it is renewable, sustainable, environment friendly. Microbial lipid have shown a great advantage as biodiesel source due to faster growth rate and larger lipid contents of microorganism (up to 80% dry weight) compared to oilseed crops and animals. However, in order to reduce the cost and operating steps of producing biodiesel from microbial lipids at the commercial scale, sugar sources that are low cost and abundant must be used and the accumulation process of microbial lipids should be simplified. Granular sludge could contain special microbial population responsible for the biological treatment of sugar-containing wastewater. This microbial population possibly consists of some heterotrophic bacteria which utilize the organic content of the wastewater to produce microbial lipids for biodiesel production. Therefore, granular sludge for sugar-containing wastewater treatment is a promising raw material for biodiesel production, which also could reduce the environmental contamination of wastewater discharge and convert excess granular sludge into valuable resources. This project is proposed to investigate the feasibility and mechanism of biodiesel production from granular sludge during sugar-containing wastewater treatment. Using organic-solvent extraction, transesterification and GC-MS et al techniques, FAMEs from microbial lipids will be analyzed during sugar-containing wastewater treatment by granular sludge. The effect of operation parameters, type of sugar-containing wastewater and other factors on biodiesel production from granular sludge will be test. The key factors of microbial lipid accumulation and biodiesel production from granular sludge during sugar-containing wastewater treatment will be identified. Throughout the experimental study to make it clear that how granular sludge could produce microbial lipids for FAMEs production during sugar-containing wastewater treatment. The research findings will help to establish a creative technical approach to produce biodiesel from wastewater sludge. Thus, an alternative means of waste disposal could be achieved. Moreover, a source of a new low-cost feedstock of lipids for biodiesel production could be obtained.

目前我国能源短缺和环境污染问题日益凸显。生物柴油是由可再生油脂原料（如微生物油脂）合成得到的清洁能源，但目前生产成本较高，纯菌发酵工艺控制严苛，急需寻找廉价、可规模收集的油脂资源，并采用高效易调控的生产工艺。我国含糖废水排放量大，如能利用含糖废水生产微生物油脂可兼顾废水处理和绿色能源生产。本课题提出利用含糖废水并采用颗粒污泥工艺生产微生物油脂及其甲酯化产物（生物柴油）的能源化研究方向，拟深入研究含糖废水颗粒污泥产油机制和方法。旨在通过考察运行参数、含糖废水类型等因素对颗粒污泥产油的影响，阐明驯化培养产油颗粒污泥的机制以及关键因素，确立颗粒污泥生长特性、生物柴油性质以及含糖废水处理效率之间的关系，建立利用含糖废水培养产油颗粒污泥的方法，使颗粒污泥在处理含糖废水同时产生物柴油，实现污水处理过程的资源回收，实现剩余污泥资源化，为中国污水处理概念厂建设提供参考依据，推进中国城市污水处理高质量发展。

生物柴油是一种可再生、环境友好型能源，利用剩余污泥制备生物柴油可同时实现废物处理与绿色能源生产的目的，具有重要的现实意义。本课题采用颗粒污泥工艺处理含糖废水的同时制备生物柴油，从制备方法、废水类型、反应器运行条件探究了影响生物柴油产量的因素，同时开发了以剩余污泥作为产油酵母营养源的生物柴油制备方法，为实现剩余污泥资源化提供理论依据和技术指导。.研究重要结果如下，1）从颗粒污泥预处理和甲酯化反应体系的角度优化生物柴油制备方法，最后将生物柴油制备方法确立为：1 g 湿污泥，7.5 mL 5% 硫酸甲醇，10 mL 正己烷，在75 °C 下甲酯化反应7 h。2）含糖废水生物处理工艺的剩余污泥油脂含量随碳源浓度和温度的提高而增加。污泥颗粒化并未产生影响生物油脂积累的生理代谢变化，但颗粒污泥沉降性能好，单位体积的生物柴油产量明显优于活性污泥。培养产油颗粒污泥时，不同初始污泥浓度会导致颗粒污泥菌群结构差异，从而影响其油脂含量。缩短水力停留时间有利于提高有机负荷，从而提高了生物柴油产量，但其成分未发生较大变化。低曝气量、高碳氮比值、充足磷源有利于颗粒污泥积累油脂，当序批式反应器中曝气量、进水C:N、进水C:P分别为0.20 L/min、70:1 和36:1时，培养的颗粒污泥的油脂含量最高，微生物自身代谢途径的调节和菌群结构的变化共同作用引起了生物柴油在产量和组分分布上的变化。3）不同预处理方法对剩余污泥碳、氮、磷释放量的影响差距显著，酶水解法有利于污泥有机碳和磷的释放，热压水解液中氮（特别是有机氮）的含量则较高，厌氧发酵有利于有机氮转化为氨氮和有机碳的进一步释放。利用经过不同预处理的剩余污泥水解液培养美极梅奇酵母，由于不同预处理方法导致剩余污泥水解液的碳源浓度以及组分存在差异，从而影响了后续酵母的代谢类型，使得制备的生物柴油在量和组成上均存在明显差异，其中酶-厌氧的剩余污泥预处理方法最有利于产油酵母积累油脂，通过序批式培养工艺则进一步促进酵母体内油脂的积累，从而提高生物柴油产量。