The recovery of secondary raw materials from street cleaning waste

The aim of this paper is to demonstrate the real possibility of recovering street cleaning waste, which accounts for an average of 4 % of all municipal waste produced, and is still mainly disposed of in landfill sites as unsorted waste. Nine new disposal centres have been built or are under construction in northern and central Italy which make use of patented technology based on a process known as soil washing, by means of which more than 70% of incoming waste in the form of inert materials may be recovered and quality certified for reuse in the building and construction industry. Recovered sand, fine and coarse gravel fully satisfy the technical standards for the specific sector of use and the environmental standards in force, which means that these materials can effectively be recovered and reused as an alternative to products newly extracted from quarries. The key factors which are always taken into consideration in the design and construction of these plants are based on the minimisation of environmental impact and the use of natural resources, maximum recovery and reuse of the materials produced and health and safety in the workplace guarantees. Although the technology applied is consolidated as a result of many years of experience, it is constantly evolving, with a view to achieving increasingly ambitious objectives for the safeguard of the environment and natural resources. The most recent plant implementations have precisely these objectives in mind, with their focus on process optimisation, specially designed and built equipment and laboratory and field studies and experiments. With particular attention paid to the waste water treatment cycle and eco-compatible solutions in terms of energy consumption, among other factors, the most recent treatment plants are able to fully reuse the washing waters, recover rainwater from roofs and ground surfaces and produce their own electricity from renewable sources (photovoltaic panels), to ensure that the plant energy requirements are satisfied in full. Without any doubt this waste can be transformed into a resource which, when correctly managed, offers a real opportunity for the safeguard of the environment and natural resources.