ABSTRACT
The environmental impact of urban waste can be considerable, as witness the ‘waste crises’ in Italy,1 the amounts of waste that are being produced, and the high priority being afforded to waste management in European environmental policy in framework programmes and in legislation. This chapter investigates the relationship between the level of organic waste separation and the diffusion of composting. This is one of the most important options for treating organic waste, which is a significant fraction of urban waste. Urban waste constitutes a large part of the waste produced by a country: in Italy it is 539 kg per person, which is about 22 per cent of all the waste produced in Italy. The organic fraction of urban waste is considered the most problematic, as it is produced in large amounts, it is malodorous, it produces biogas, and it leaches in landfills; it also reduces the heating value of waste going for incineration, which, in turn, reduces the efficiency of the combustion process and subsequent energy recovery. As organic waste constitutes approximately 30 per cent of the waste collected, its separate collection is believed to be necessary for Italy to reach the ambitious recycling targets set by European environmental policy. Composting means the transformation of organic waste into fertilizer,
which closes the carbon cycle loop by returning beneficial organic matter to the land. It facilitates the removal of organic material from the streams of waste going to landfills and incinerators, thereby saving space in landfills and reducing pollution. It is therefore an example of a sustainable treatment method for wastes. The European Waste Directive, recognizing that the various systems of
treatment for waste have different impacts on the environment, has established a hierarchy of technological options for waste management, with waste prevention at the top, followed by recycling and recovery. This hierarchy of technologies, where disposal is the least preferred option, is based on life cycle assessment (LCA) and political choice but has been challenged on several counts, including costs and benefits. However, composting and the separation of organic wastes score well in the most recent cost-benefit analysis. It seems, therefore, that composting is an interesting case for analysis, and especially as an example of how policies can influence the choices of local governments, which in turn influence the choice of treatment system.
