Background Ever-increasing waste production and the increasingly hazardous nature of many waste streams pose ever greater waste management challenges. As part of the EU response, the European Commission's thematic strategy on waste prevention and recycling aims to promote more sustainable patterns of resource use. It advocates the following hierarchy of waste management solutions: 1. Prevent waste in the first place; 2. Re-use the product; 3. Recycle or compost the material; 4. Recover energy through incineration; and 5. Product disposal in landfill. Nevertheless, currently at least 14 000 tonnes of potentially recoverable material is landfilled in the Tuscan basin served by the project partners each year. Currently, solid-waste-treatment plants for unsorted urban waste are generally limited to pre-processing to allow further fully automated treatment and separation of the organic and dry fractions. Some of the dry fraction is incinerated for energy production, but much is simply sent to landfill. The organic fraction is stabilised and often used as a landfill cover layer. Current processes do not focus on materials recovery, with the exception of metals; iron is removed through the industrial process of deferrisation. The technology exists for recovering non-ferrous materials from this fraction. However, there is little experience of these treatment lines and systems still need to be integrated taking into account end-use requirements. Objectives The ARIEL project aimed to demonstrate the availability of viable solutions for routinely recovering materials from the dry fraction of undifferentiated - unsorted - urban solid waste. It sought to streamline the recycling of a recoverable quota of materials from municipal waste treatment processes and thus avoid landfilling. The specific defined objectives for achieving this overall goal were to: Set-up and run a demonstration site for a year, showing the viability of recovering 1 000 tonnes of materials from some 15 000 tonnes of the dry fraction of undifferentiated urban solid waste; Foster industrial end-use markets for recovered materials - especially local/regional short chains - by demonstrating that end-use requirements can be met and by devising suitable contractual models; Use the knowledge gained to produce a model that links waste-input patterns, end-use requirements and market channels in a support tool that can be used to make decisions on adapting processes or technologies for material recovery.The project targeted full-scale implementation of the project’s material-recovery process after LIFE. It planned to lead to the investment decision to develop a full-scale process capable of treating the dry fraction coming from 477 000 tonnes/yr of unseparated waste, generating more than 14 000 tonnes/yr of recovered material for industrial use. It also aimed to see inclusion of the project’s process in local and regional waste management plans. It thus hoped to create further and long-term reductions of landfilling beyond the achievements of the demonstration site. Results The ARIEL project successfully assembled and demonstrated a pilot plant for recovering recyclable materials from municipal waste. As well as showing the economic and technical feasibility of extracting 3% of the waste volume as recyclable plastic, it also worked to both demonstrate and develop the potential market for the recovered materials. The project thus promoted a viable alternative to the landfilling of waste. The project planned to integrate the pilot process into an existing mechanical recovery facility of the partner company ASM in Prato. It conducted tests of air, optical and ballistic sorting systems and identified the best option as being the integration of two optical sorter machines after the existing ballistic separator. The new optical systems were designed to treat both: the rolling heavy fraction – composed mainly of wood, metals and large plastic parts; and the flat light fraction, composed of foils, textile paper and cardboard. The pilot plant was able to obtain a recovered plastic fraction similar in quality to that derived from a fully differentiated waste sorting scheme. The recoverable stream of plastic was estimated to be equal to 3% of the total undifferentiated input. Furthermore, the project demonstrated the economic viability of the process given the value of the recovered materials and the avoidance of land-filling costs. The project also worked to demonstrate and encourage the market for the recovered materials. It found 572 companies across Italy dealing with plastic recycling in various ways and identified 182 that could be interested in the ARIEL process. It worked to raise the awareness of the project’s results and was able to obtain twenty-one signed letters of intent from end users and their associations confirming their interest in purchasing and using the recovered plastic. The project also went on to fully informed, about the potentiality of the ARIEL process to, decision and policy makers, mainly at regional and local level in order to influence legislation on recycling as at the present moment it focuses on waste selection. The project estimated that use of the ARIEL process for all municipal waste in the provinces of Prato and Florence alone would avoid 45 000 m3 of landfill volume each year. This would be equivalent to around 15 000 t of plastics and 17 500 t of CO2 equivalent emissions per year. The ARIEL process can be fully integrated into any municipal waste treatment plant and this means that, at full scale, ARIEL could create new small recycle chains and new job opportunities. A study on the potential impact of the project on the local production system highlighted that plastic business is perceived in growth. Therefore, Ariel would be a "support to the growth and consolidation" of the companies that commercialise and/or use recycled plastic. In 2012 Publiambiente operated in 28 Tuscan municipalities and collected a 54 per cent of separated waste. Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section). An ex-post follow up visit, carried out in December 2015 by the LIFE external monitoring team, concluded that the issues addressed by the project remain highly relevant, that the project was innovative and technically well-implemented, and that the partnership established worked well and continues to provide waste management services. The project team acquired knowledge concerning the options available, and the problems arising, when recovering plastic material from undifferentiated waste. However, the project did not achieve its expected long-term environmental benefits, due to the high cost of the process, the low involvement of public authorities and private sector operators, and the fact that at national and regional level the problem addressed (excessive amounts of potentially recoverable plastic waste sent to landfill) was solved by other solutions (e.g. higher levels of waste separation) during the project’s lifetime. The recovered plastic (from undifferentiated waste materials), in this case, did not meet the market requirements. Therefore, the option tested by the project was not streamlined into the waste management strategy adopted by the relevant public authorities.