The environmentally sustainable waste management strategy is an important objective for all European and Mediterranean countries, the key to which is the separation of biowaste at source. The revised framework directive on waste (2008/98/EC) contains specific provisions for the management of biowaste including the promotion of bio-waste separation at source. Moreover, according to recent studies at European level, the separation of biowaste at source is considered a prerequisite for ensuring efficient allocation and utilization of the produced compost market. Apart from the diversion of the organic fraction of municipal solid waste from the landfills which is achieved by separation at source of biowaste (compliance with EU Directive 1999/31/EC on the landfill), it also improves the calorific value of the remaining municipal solid waste and creates a cleaner stream of biowaste allowing the production of high quality compost. In recent years there has been a significant increase in separation at source programs of biowaste in many regions of the European Union and it is regarded as a successful option for waste management.
In Athens and in the wider Greece, municipal solid waste is collected in two streams, mixed waste and packaging waste. Packaging waste collected by local authorities in cooperation with the Greek Recovery & Recycling Corporation (EEAA) and ends up in Recycling Materials Sorting Centres (KDAY) while the remaining mixed waste is collected by local authorities and ends up in landfills or units of Mechanical and Biological Treatment (MBE). In Athens, there is a MBE unit (Mechanical Recycling and Composting Plant – EMAK) in Ano Liosia, which treats approximately 20% of the total waste generated in the area producing RDF (waste derived secondary fuel) and low-quality compost. In Greece, the separation of biowaste at source has never been organized, as there is not adequate infrastructure to allow proper management. The Regional Solid Waste Management Plan (PESDA) of Attica and the action plan of the Association of Municipalities and Communities of Attica (ESDKNA) provide for the construction of three new composting facilities in the greater Athens area (Fyli, Gramatiko and Keratea), which will treat pre-sorted organic waste. Therefore, the separation of biowaste at source is essential.
From an environmental perspective, the importance of integrated management of biowaste, with the integration of separation systems, lies in diverting them from landfills and their parallel exploitation. During the deposition of this stream of waste in landfills conditions of anaerobic biodegradation occur with consequent emission of significant quantities of biogas (a mixture of organic and inorganic gases) and the production of leachate heavy in high organic and inorganic load. This process takes place for several years after disposal. The major management problem regarding the burial of bio-waste is the emission of biogas with high methane content which is one of the chemically active gases contributing to climate change. It is worth noting that the estimated quantities of anthropogenic methane emitted globally from the disposal of bio-waste in landfills, amounts to 11% for the year 2010 (GMI, 2010). Therefore, diverting them from landfills can contribute significantly to reducing the impact on climate change (Smith et al., 2001). Besides air pollution resulting from disposal of this stream of solid waste in landfills, its content in organic matter and nutrients is no longer available for recycling and reuse.