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Une approche systémique en faveur d'une gestion circulaire des flux de nutriments dans les zones métropolitaines d’Amérique du Sud : relier le métabolisme urbain et la planification urbaine stratégique

Year: 2024
Type: dissertation
Abstract: "Cities and metropolitan areas are essential to sustainable development, especially in managing nutrient flows such as fertilizers, food, and organic waste. However, integrating urban metabolism and nutrient circularity into planning remains challenging due to fragmented approaches. As cities grow and face climate change, the key question is: how can urban strategies better incorporate nutrient circularity? This research identifies and measures factors influencing nutrient flow management, proposing a three-step approach: identifying key factors, assessing them with a planning focus, and integrating findings into strategic planning. The focus is on South America, given its significant role in agrifood production and urbanization.Article 1: This study develops a framework to measure Nutrient Circularity Capacity (NCC) in South American metropolitan areas (SAMAs), evaluating environmental, technical, economic, social, and political factors. It identifies 12 influencing factors across four themes—Material Flow, Food & Feed Value Chain, Knowledge Base, and Institutional Support—and links them to 11 indicators using multi-criteria analysis. Results show Montevideo, Uruguay, leading in NCC due to government support and innovation, while Paraguay and Bolivia rank lowest. The study emphasizes the need for localized strategies, with investments in innovation, waste management, and peri-urban agriculture as critical elements for improving nutrient circularity in the region.Article 2: This research introduces a multidimensional diagnostic framework to enhance nutrient circularity in urban planning, bridging the gap between urban metabolism and practical planning. Applied to the Metropolitan Region of Santiago de Chile (MRSC), the framework assesses nitrogen (N), phosphorus (P), and potassium (K) flows across spatial, material, and social dimensions. Utilizing the UN's *Our City Plans* toolbox, data from local databases, literature, and 34 interviews helped map the agri-food-waste system. The findings reveal heavy reliance on imports for nutrients, significant losses from landfilled waste, and underutilized manure. Recovery rates for N, P, and K were 78%, 85%, and 52%, respectively, driven mainly by wastewater treatment. The diagnostic identified 45 key actors, highlighting the need for better collaboration across sectors. This framework supports planners in addressing nutrient flow challenges and enhancing collaboration between urban and rural sectors for improved circularity.Article 3: This study presents a framework that integrates nutrient-flow diagnostics with stakeholder inputs and local strategies, constructing scenario narratives for circular urban development. Applied to Santiago, the framework connects the diagnostic phase with scenario building through three key tasks: contextualizing data, synthesizing findings, and creating narratives. Key challenges include limited waste treatment infrastructure, regulatory constraints, and collaboration barriers. Three narratives were developed to explore: increasing composting capacity for green urban areas, better utilization of animal residues in agriculture, and improving WWTP technologies for nutrient reuse. The framework bridges gaps in current urban plans and proposes strategies for enhanced nutrient circularity. By grounding decisions in stakeholder engagement and multidimensional analysis, it fosters systemic changes for sustainable urban development.In conclusion, this research presents a comprehensive framework for advancing nutrient circularity in South America by systematically analyzing nutrient flows and enhancing strategic planning. It provides a structured, systemic approach to assessing key factors and translates findings into actionable insights for decision-makers and planners, helping cities and regions improve circular nutrient management practices."
Language: English
Open Access status: green
OpenAlex ID: W7124516564
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