UNSORTED MUNICIPAL WASTE TREATMENT PLANT ANALYSIS: EMILIA-ROMAGNA REGION CASE STUDY Extended abstract

Better knowledge of complete Municipal Solid Waste (MSW) cycle dynamics could allow MSW plan decision makers to reach the waste management goals that are, at present, still far from being achieved (Bianchini et al., 2011). Thus, in order to identify characteristics of the existing and/or planned MSW treatment plants, EmiliaRomagna started a deep analysis to optimize energy consumption, energy production, environmental impact and management costs of whole MSW system in comparison with the final “Regional plan for waste management” (PRGR, Piano Regionale di Gestione dei Rifiuti, in Italian) goal. New Emilia-Romagna PRGR is now under definition. MSW collection can be divided into two main streams: separate collection and unsorted collection. Law Decree 152/2006 defined separate collection as “the collection where a stream of waste is kept separate depending on kind and nature of the waste in order to facilitate a specific treatment”. In 2011 Emilia-Romagna reached 52.9% separate collection on total MSW collection, which means about 356 kg/year collected per inhabitant (ARPA and Emilia-Romagna, 2012). Separate collections are not recoverable at all; moreover, the percentage of unrecoverable inside separate collection increases with separate collection increasing (Consonni et al., 2011). So, treatment plant for unsorted MSW must be properly designed taking into account also contribution from separate collection discards. In 08/98/CEE MSW hierarchy landfill disposal is the last step. Therefore, an effective and efficient MSW management is one that ensures the minimization of the waste in landfills. Nevertheless, a quantity as marginal of waste will still be in landfill (i.e. waste produced by selection and/or recycling plant, waste products from energy recovery plants). Furthermore, it is desirable to ensure a residual capacity greater than that strictly necessary in such a way operating safety, for example, relating to shutdown of Waste-To-Energy (WTE) plants. Energy recovery from waste is part of the additional forms of waste recovery and different from recycling. Thus, MSW energy recovery is a solution both for waste valorization and landfill disposal minimization. Mechanical-Biological Treatment (MBT) of residual MSW was born to achieve the target of reducing biodegradable waste that goes to landfills, according to 99/31/CEE. Over the years MBT has been developed to improve also the sorting of recyclable materials. MBT generally consists of a mechanical pre-processing stages followed by biological stages that reduce and stabilize biodegradable matter under controlled aerobic and /or anaerobic conditions. MBT with anaerobic stabilization process has the further advantage of energy recovery thanks to biogas production. The mechanical pre-processing is designed both for sorting recyclable materials and particle size fractionation and homogenization of waste, thus optimizing the following biological process. Therefore, MBT plants can represent an interesting alternative to direct unsorted MSW landfill disposal and, in certain condition, also to WTE (Cimpan and Wenzel, 2013).