Closing the life cycle of phosphorus in an urban food system: the case Almere (NL)

In order to explore the possibilities of a local food system and its effects on the nutrient cycle, a desk study was executed for the urban region Almere, a Dutch city located in the Flevo Polder with about 200,000 inhabitants. This desk study takes this urban perspective as starting point in the search of measures to maintain future food productivity whilst decreasing the demand (and dependence) of external resources. The study focussed on phosphorus (P) as this element is essential for food and feed production while the resources are finite and, it is technically feasible to recover it from the urban waste flows. Three scenarios were distinguished each different in the extent to which the food is produced locally. The first scenario, “Current”, refers to the current situation in which only a small part of the food, estimated at 5% for all food products, is produced and processed locally. In this scenario the reuse from waste is limited and occurs via compost (e.g. kitchen waste) and digestate. In the second scenario, “Hybrid”, the food is as far as possible produced locally except for products that cannot be grown locally (e.g. coffee, tea, exotic fruits). Also a part of the animal feed ingredients (e.g. soybean meal) are still imported. Within the Hybrid scenario two sub-scenarios are distinguished: (a) with a limited P reuse, only via compost/digestate (as in scenario Current) and (b) with a maximal (up to 90%) recovery of P from waste. Finally, in the third scenario, “Self-Sufficient”, all feed ingredients are also grown locally. Only food products that cannot be grown locally are still imported. P recycling from waste is maximal (90%).