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Rapid urbanisation in developing countries intensifies the challenges of making sufficient food available for the increasing urban population, and managing the related waste flow. Unlike in rural communities, there is usually little or no return of food biomass and related nutrients into the food production process. Most waste ends up on landfills or pollutes the urban environment. This is transforming cities into vast nutrient sinks,while the rural production areas are becoming increasingly nutrient deficient (Drechsel and Kunze, 2001).