Pre-treatment Strategies for Anaerobic Digestion

随着城市污水污泥数量的增加，处理的质量和水平在加拿大和世界许多地方都受到严重关注，特别是加拿大每年产生约660，000吨污泥。随着对污泥处置的严格规定的实施和更多垃圾填埋场的关闭，污泥管理变得越来越具有挑战性。加拿大的许多城市已经制定了积极的废物转移目标，以减少目前废物管理做法的环境足迹。因此，人们越来越重视开发先进可靠的生物能源技术和废物增值资源，这可以带来废物转用和创收的双重好处。厌氧消化是迄今为止最广泛实施的将废物转化为富含甲烷的沼气的废物生物能源技术。另一方面，在发酵阶段之后终止该过程和回收挥发性有机酸的可能性受到特别关注。这些挥发性有机酸可用作各种高附加值产品的原料，包括生物塑料、生物能源、液态烃、用于生物柴油生产的脂质、用于生物营养物去除的电子供体。目前，不仅大多数现有的厌氧消化器的挥发性固体稳定化效率是适度的且相对低，而且生物固体也难以分解，需要高的化学调节剂量。本研究的主要目的是开发一种新型的污泥化学和机械联合预处理工艺，以提高消化效率和提高有机负荷率。此外，本研究计划旨在了解水热预处理与真空发酵工艺相结合生产高挥发性脂肪酸的可行性。

With increasing quantity of municipal sewage sludge, the quality and level of treatment are of serious concern in Canada and many parts of the world, specifically, about 660,000 tons are produced annually in Canada. With the implementation of strict regulations on sludge disposal and closure of more landfills, sludge management is becoming increasingly challenging. Many municipalities across Canada have already set aggressive waste diversion goals to reduce the environmental footprint of current waste management practices. Thus, there has been growing attention to developing advanced and reliable technologies for bioenergy and value-added resources from waste, which can provide dual benefits of waste diversion and revenue generation. Anaerobic digestion is by far the most widely implemented waste-to-bioenergy technology for converting waste to methane-rich biogas. On the other hand, the possibilities of terminating the process after the fermentation stage and recovering volatile organic acids have received particular attention. These volatile organic acids can be used as a feedstock for various high value-added products, including bioplastics, bioenergy, liquid hydrocarbons, lipids for biodiesel production, electron donors for biological nutrient removal. Currently, not only the volatile solids stabilization efficiency of most existing anaerobic digesters is modest and relatively low but also the biosolids are difficult to dewater requiring high chemical conditioning doses. The main goal of this research proposal is to develop a novel sludge combined chemical and mechanical pre-treatment process to enhance the digestion efficiency and increase the organic loading rate. Furthermore, this research project aims to understand the feasibility of combining the hydrothermal pretreatment with the vacuum fermentation process for higher volatile fatty acids production.