Innovative approaches for volatile fatty acids recovery from wastes

有机废物产生量的增加以及对其最终处置的监管要求是加拿大各地严重的经济和环境问题。填埋有机废物对环境和公众健康构成重大风险。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。厌氧消化过程中产生的沼气可以转化为热能和电能。厌氧消化过程依赖于微生物对复杂有机物的分解。有机物在第一阶段降解为各种挥发性有机酸，称为产酸发酵阶段。然后，这些有机酸在第二阶段转化为甲烷和二氧化碳。近年来，在发酵阶段之后终止该方法并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，挥发性有机酸是通过化学（羧化和氧化）和生物过程从化石燃料和纯糖商业生产的。 该研究计划的重点是开发一种新型的产酸发酵系统，将真空和水热技术相结合。真空技术的应用可以提供多种好处，例如最大限度地提高工艺稳定性，通过连续去除发酵产物以更高的产率获得高品位的挥发性有机酸。此外，水热工艺提供了通过溶解提高原料的生物转化潜力的极好机会。该项目产生的先进知识将加强加拿大在开发尖端可再生能源和资源采集技术以实现低碳未来方面的持续努力。

The increased organic waste generation and the requirements regulating their ultimate disposal are serious economic and environmental concerns across Canada. Landfilling of organic wastes poses significant risks to the environment and public health. 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. The biogas produced during anaerobic digestion can be converted into heat and electricity. The process of anaerobic digestion relies on the microbial breakdown of complex organic matter. Organic matter is degraded to various volatile organic acids in the first stage, known as the acidogenic fermentation stage. Then, these organic acids are converted to methane and carbon dioxide in the second stage. In recent years, 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, volatile organic acids are commercially produced through chemical (carboxylation and oxidation) and biological processes from fossil fuels and pure sugars. The proposed research program focuses on developing a novel acidogenic fermentation system integrating vacuum and hydrothermal technologies. The application of vacuum technology can provide multiple benefits, such as maximizing the process stability, high-grade volatile organic acids with higher yield by continuously removing fermentation products. Moreover, the hydrothermal process provides an excellent opportunity to boost the bioconversion potential of feedstock via solubilization. The advanced knowledge generated from this project will strengthen the continuous efforts of Canada in developing cutting-edge renewable energy and resource harvesting technologies to achieve a low-carbon future.