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，每年产生惊人的370万吨食物和有机废物，其中约60%的食物废物最终被填埋。从循环经济的角度来看，由于温室气体的排放和营养循环的破坏，食物垃圾填埋不是一个可持续的选择。这些因素加上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、材料和能源效率，是食物浪费加剧的关键驱动因素。该项目的目标是在传统的厌氧消化过程之外，创造创新和先进的食物垃圾价值处理过程，在加拿大建立一个低碳和经济高效的循环生物经济。这将通过将食物垃圾生物转化为羧酸盐来实现，羧酸盐是合成目前无数化石燃料衍生产品的高价值基石，如聚合物（塑料）、醇（例如作为生物燃料的丁醇）、酮和烯烃。本研究项目将推动以产酸混合培养发酵为基础，结合工艺设计与优化、微生物群落工程、通过耦合上下游系统进行工艺强化，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在内的多产品价值链的高效、高价值食物垃圾资源回收系统的开发。具体来说，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，以提高羧酸盐的生产，重点是进料批和连续设计系统，高负载条件和致酸气体压力和成分的影响。（ii）研究微生物群落结构和功能动态，以(a)确定在特定工艺条件下富集的特定微生物群，并产生增强和/或所需的羧酸盐；(b)开发用于特定羧酸盐合成的有效生物增强系统。（iii）开发耦合发酵-提取系统，即原位产物回收（ISPR）系统，从产酸发酵罐中提取羧酸盐，并制定同时减轻羧酸盐抑制和高回收率的提取方案。确定通过生物转化技术从羧酸盐中获得二级高价值产品，如MCFA和生物塑料的方法。该计划将提供具有现代技能和能力的高素质人才（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。这些熟练的hqp将促进加拿大和世界各地这些清洁技术的发展。

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.