More than half of the world’s population currently resides in deltas and cities therein, contributing to a host of environmental problems (e.g. pollution of land, water and air), but at the same time, offering a range of opportunities. As centres of resource conversion, cities present an opportunity to link resource flows and move towards a circular metabolism. Urban agriculture and New Sanitation are two possible concepts facilitating such a metabolism.
More than half of the world’s population currently resides in cities, contributing to a host of environmental problems. Cities currently engage in a linear metabolism of production, consumption and disposal, converting resources into waste.
Cities also present an opportunity to link resource flows and move towards a circular metabolism, in which waste from one process equals food for another. Urban agriculture (UA) systems and new sanitation (NS) systems are gaining momentum as measures to improve urban resource management. The former aims to localize food provisioning and the latter to reorganize waste management to recover valuable resources. Both systems can be integrated and combined to exchange water and nutrient flows for mutual benefit.
To integrate UA and NS systems, resource input-output flows of need to be described and matched for compatibility in terms of quantity and quality – taking into account parameters for human and environmental hygiene (e.g. heavy metals, pathogens). No methodological tool currently exists to match their input-output flows and establish a “common language” between the two systems.
To start, data on the quantity and quality of the input demands from UA systems is lacking, as UA is largely unregulated. Second, data on the quantity and quality of the products produced by NS systems has, and continues to be, researched however their suitability for reuse in UA is uncertain. To further match input-output flows, the dynamic patterns at different temporal (e.g. diurnal, annual) and spatial (e.g. household, neighborhood) scales need to be considered. While climate (e.g. Amsterdam’s oceanic climate vs. Jakarta’s tropical monsoon climate )and urban typology (e.g. densely vs. lightly populated; skyscrapers vs. slums) also influence resource input-output compatibility.
This research develops a framework to measure resource flows and to evaluate the benefits and challenges of integrating these systems in terms of improved self-sufficiency and sustainability. It will provide clear recommendations on where and to what extent urban agriculture and new sanitation can create fruitful synergies and local solutions.