Determining best practices for sustainability of the circular bioeconomy: Characterizing flows and transformations of organic carbon, nutrients and contaminants

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The guiding principle and long-term goal of my research program is to develop new technologies and best management strategies for recycling municipal organic residues to agriculture as part of a sustainable circular bioeconomy. Commercial agriculture is based on a linear extractive economic model that rewards maximum production while deemphasizing sustainability, soil health, and food quality. By contrast, a circular economic model seeks minimum depreciation and maximum reuse of resources. Soil health depends on abundant soil organic matter. The health of soils, crops and humans can be facilitated and sustained by responsible management of organic resources. In Canada, 2.5 Mt wet biosolids and 34 Mt municipal solid waste (50% organic) are generated annually. Processing these materials by composting, anaerobic digestion, etc. and applying the products to agricultural land recycles organic carbon and micro and macronutrients and helps to achieve sustainable agriculture and a circular economy. Efficient management of these materials benefits agronomy and mitigates climate change by sequestering carbon and offsetting use of chemical fertilizers. My long-term goal will be achieved by short-term objectives to quantify movement and transformation of organic carbon, macro and micronutrients through waste management and agro-ecological systems. We will also track pollutants such as microplastics, metals, and greenhouse gases (GHG). The fate of microplastics, how they concentrate and transform in ecosystems is still largely unknown. Trace metals, even those which are micronutrients, are hazardous if overconcentrated. Finally, data about GHG emissions from organics recycling are incomplete. We will sample organic material along the paths through the bioeconomy: wastewater biosolids, organic fraction of municipal solid waste, composted and biodigested organics, soil, crops, and food. We will quantify the organic carbon, macronutrients and micronutrients contents in these materials, as well as microplastics, metals, and GHGs. We will use the data in Material Flow Analysis (MFA) and construct process-based models to simulate how these materials evolve under different management strategies and climate scenarios. The models will be used to simulate management strategies for the handling and recycling of organic residues for use in agriculture. Life Cycle Analysis (LCA) will be done to assess the environmental impacts of the different strategies and to recommend Best Management Practices (BMPs) to maximize benefits and minimize risks. Finally, we will use these models to predict the impact of possible climate scenarios and establish BMPs for mitigation and adaptation. The results of this research program will help Canadians responsibly valorize organic wastes, improve agricultural soils, produce abundant and healthful food, and mitigate climate change impacts as we transition from a linear to a circular bioeconomy.