Mining and minding food waste through carboxylate value-added platform

在全球范围内，食物垃圾约占城市固体废物的30-50%，而填埋仍然是主要的废物处理技术。在安大略省，每年产生的食物和有机废物高达370万吨，其中约60%的食物废物最终被填埋。从循环经济的角度来看，考虑到温室气体排放及养分循环的破坏，填埋餐厨垃圾并非可持续的选择。这些因素沿着加拿大对可持续发展目标12.3的承诺，即到2030年将食物浪费减少50%，促进环境保护，粮食安全以及材料和能源效率，是减少食物浪费的关键驱动力。该计划的目标是创造创新和先进的食物垃圾增值工艺，超越传统的厌氧消化工艺，在加拿大建立低碳和经济高效的循环生物基经济。这将通过将食物垃圾生物转化为羧酸盐来实现，羧酸盐是用于合成无数目前化石燃料衍生产品的高价值构建块，例如聚合物（塑料）、醇（例如丁醇作为生物燃料）、酮和烯烃。 该研究计划将促进基于产酸混合培养发酵的有效的高价值资源回收系统的开发，包括工艺设计和优化，微生物群落工程，通过耦合上下游系统的过程强化，以及包括短链和中链脂肪酸（SCFA，MCFA），生物塑料和液体生物燃料前体的多产品价值链。具体而言，该计划有四个主要目标：（i）开发创新的生物反应器配置和操作策略，以提高羧酸盐生产，重点是补料分批和连续设计系统，高负荷条件以及产酸气体压力和组成的影响。 （ii）调查微生物群落结构和功能动态，以（a）鉴定在特定工艺条件下富集的特定微生物群，并产生增强的和/或所需的羧酸盐，和（B）开发用于特定羧酸盐合成的有效生物强化系统。 （三）开发耦合发酵-提取，即原位产品回收系统，从产酸发酵罐中提取羧酸盐，并开发反萃取方案，以同时缓解羧酸盐抑制及其高回收率。(iv)建立通过生物转化技术从羧酸盐中获得MCFA和生物塑料等次级高价值产品的方法。该计划将提供高素质的人员（HQP）在废物处理，生物炼制，工程系统的微生物生态学和回收生物产品的应用等新兴领域的现代技能和能力。这些熟练的HQP将促进这些清洁技术在加拿大和世界各地的发展。

Globally, food wastes constitute about 30-50% of the municipal solid waste while landfilling remains the main waste treatment technology. In Ontario, a staggering amount of 3.7 M tonnes/year of food and organic waste is generated and about 60% of food waste ends up in landfills. From the circular economy perspective, landfilling of food waste is not a sustainable option in view of greenhouse gases emission and breakdown of nutrient cycling. These factors along with Canada's commitment to Sustainable Development Goal 12.3 to reduce food waste by 50% by 2030 and promote environmental protection, food security, and material and energy efficiency are the key drivers for valorization of food waste. The goal of this program is to create innovative and advanced food waste valorization processes beyond the conventional anaerobic digestion process to build a low carbon and economically efficient circular biobased economy in Canada. This will be achieved through the bioconversion of food waste to carboxylates which are high-value building blocks for the synthesis of a myriad currently fossil-fuel derived products such as polymers (plastics), alcohols (e.g. butanol as biofuel), ketones and olefins. This research program will promote the development of an effective high-value resource recovery system from food waste based on acidogenic mixed culture fermentation incorporating process design and optimization, microbial community engineering, process intensification via coupled upstream-downstream system, and multi-product value-chain including short- and medium-chain fatty acids (SCFA, MCFA), bioplastics and liquid biofuel precursors. Specifically, the program has four primary objectives: (i)Develop innovative bioreactor configurations and operating strategies for enhanced carboxylate production with focus on fed-batch and continuous design systems, high loading conditions and impact of acidogenic gas pressure and composition. (ii)Investigation of microbial community structure and function dynamics to (a) identify specific microbial groups enriched under specific process conditions and produce enhanced and/or desired carboxylates and (b) develop efficient bioaugmentation systems for specific carboxylate synthesis. (iii)Develop coupled fermentation-extraction i.e. in-situ product recovery (ISPR) systems to extract carboxylate from acidogenic fermenter and back extraction protocols for simultaneous alleviation of carboxylate inhibition and their high recovery. (iv) Establish the methods for deriving secondary higher-value products such as MCFA and bioplastics from carboxylates through biotransformation techniques. The program will provide highly qualified personnel (HQP) with modern skill sets and competencies in emerging areas of waste treatment, biorefinery, microbial ecology for engineered systems, and applications of recovered bioproducts. Such skilled HQPs would foster the development of these clean technologies across Canada and around the world.