City-Level Decoupling-Full Report

the developed world, even cities where material stocks must still be built up often generate a significant amount of building rubble from new construction as old structures are demolished or rapidly replaced; this resource could be recycled into new construction. Similarly, organic wastes in the form of food, sewage or animal wastes contain valuable nutrients, gases and water that can be re-used to meet the needs of the city. Instead of viewing waste organic matter as something offensive to be dumped and buried as quickly as possible, the city of Stockholm has built a large-scale municipal sewage treatment systems that captures methane to power its bus fleet, while reducing greenhouse gases released into the atmosphere; the remaining biomass can be composted and used to enhance the fertility, water retention and even CO 2 absorption of soils. Wastewater is a potential

• The generation of biogas from crop residues, manure and slaughterhouse waste to run public buses in Linköping, Sweden; • Fuelling district heating with waste woodchips from nearby logging activities in Växjö, Sweden;

• The use of wastewater to irrigate urban farms in Accra, Ghana;

• Treating waste water on-site for re-use in toilet-flushing, irrigation and other applications in Beijing, China; • The use of methane for energy generation and processed leachate for irrigation and dust suppression at Mariannhill Landfill site in Durban, South Africa; • The collection of solid and liquid waste from waterless toilets as a source of nutrients for agriculture in Lilongwe, Malawi; and • The collection of food scraps for conversion to compost at municipal composting facilities in Portland, Oregon, USA. Every city has a unique configuration of interests and changing conditions bring unpredictable new configurations, alliances and strategic initiatives. As resource prices rise, new technological options become commercially available to those in the public, private and non- profit sectors seeking new opportunities for tackling old problems. However, this will depend on the existence of appropriate know-how and the capacity for innovation within each specific city. More efficient usage of limited resources, improved management of renewable resources and the re-use of wastes are becoming the focus of new initiatives that could well bring about the decoupling of rates of resource use from well-being and economic growth. For whole-system efficiencies to be realised at the city scale, strategic coalitions with a shared vision for decoupling will need to emerge. The following section describes how transitions toward sustainability at the city scale might look, in order to formulate an agenda for facilitating transitions toward decoupling in different contexts.

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source of water for non-potable uses and the nutrients it contains can be reclaimed and used as affordable natural fertilisers.

Examples of the re-use of resources from the case studies include:

• The selling of 'waste' products from one industry as inputs to another in Kitakyushu Eco-Town, Japan;

• The separation, collection and recycling of household wastes in Curitiba, Brazil;

• The collection, drying and grinding vegetable peels to produce nutritious animal feed in Kampala, Uganda;

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