Background The increasing generation of waste and the limited capacity of waste-treatment installations make prevention a principal priority of waste management for European cities. Organic waste is a particular target, as it constitutes a very poor source of energy and can easily be diverted from incineration. Between 300 and 600 kg of municipal solid waste (MSW) are generated per inhabitant per year in Europe. Around 100 kg is organic waste, 10% of which can be avoided by limiting food waste through increasing environmentally friendly behaviour in such areas as shopping and cooking. Some 30-70% can be composted. The benefits of separate collection of organic waste within households include diverting easily biodegradable waste from landfills, enhancing the calorific value of the remaining MSW, and generating a cleaner biowaste fraction that produces higher quality compost. After setting up a waste-sorting scheme, Rennes Métropole launched an ambitious waste prevention policy in 2005 with the goal of bringing down the production of residual municipal solid waste from 240 kg/person/yr in 2005 to 200 kg/person/yr by 2011. Objectives The MINIWASTE project aimed to demonstrate – in accordance with the new Waste Framework Directive 2008/98/EC – that it is possible to significantly reduce the amount of organic waste from households in a manageable and sustainable way. The project planned to engage households in limiting food waste and favouring collective or individual composting of food and green waste in three urban areas. It was implemented at full scale in Rennes Métropole (France) and Lipor (Portugal), and at pilot scale in Brno (Czech Republic). In Rennes Métropole, the project hoped to involve more than 50% of the population living in detached houses and about 25% of those living in collective buildings within eight years. It was expected that this would lead to a reduction of more than 80% of their organic waste. The project planned to set up appropriate measurement protocols and control systems to verify targets and inform continuous technical progress. A specific set of monitoring protocols was to be developed and implemented to ensure the quantity and quality of the compost produced was in compliance with EU standards and to compare the efficiency of different kinds of composter bins. It also sought to show that the costs of implementation and monitoring of waste-reduction actions can be offset within a few years by the quantity of waste diverted from processing. Finally, it aimed to carry out awareness campaigns and disseminate recommendations and guidance notes for other European cities. Results The MINIWASTE project allowed the beneficiaries to test, assess and improve local waste reduction plans for the three regions involved. As one of its most important accomplishments, the project increased people's knowledge about composting and about the reduction of food waste. The objective was to transform waste into raw material and get the community involved in shared gardens so that this valuable material can be recovered. The results in numbers: about 8 500 t of organic waste were diverted. Nearly 12 000 people were trained in composting techniques. MINIWASTE distributed nearly 15 000 individual compacter bins. Around 7 700 people took part in communal composting. The project team also organised 210 events or conferences and produced a variety of dissemination materials. Rennes, Lipor and Brno developed comprehensive strategies in the framework of the project to reduce biowaste at the source. These strategies covered in particular the distribution of individual composter bins to citizens, the promotion and support of collective composting sites (in apartment buildings, schools, etc.), and the development and operation of composting demonstration sites. They also implemented a series of promotion and training activities for composting at home (single-family homes and apartment buildings) and in schools, cafeterias, and restaurants, etc. The three regions also supported a network of composting guides and assistants to boost composting and teach citizens how to compost. Other activities at all three sites included indoor composting with witness households weighing their bio-waste and the fight against food waste in restaurants and schools. MINIWASTE aimed to change people's habits in the long term by making them more aware of the biowaste they produce, its value as a resource and the advantages of composting. As one example of this transformation, gardening stores and retailers in the areas are now selling composting bins. When the project started at the beginning of 2010, this equipment was only available from specialised companies. The change of habits has also had an impact on organic farming, respect for the environment and sustainable practices in daily life. The MINIWASTE actions will go on in the framework of the established waste management plans. The project consortium believes that it is not enough to provide technical tools to change behaviour. Continued support is also necessary to get the population to stay involved in the long term. The consortium stresses that composting requires communication to be maintained in order to inform new comers about the system. Furthermore, the inhabitants involved in local composting must be informed about the results in order to keep them motivated. In addition, the consortium concludes that promoting organic waste management practices cannot rely on a network of volunteers alone. Instead, a system of salaried ambassadors must be set up to keep promoting good practices. Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).