Transactions of the ASABE Vol. 56(5): © 2013 American Society of Agricultural and Biological Engineers ISSN 2151-0032 DOI 10.13031/trans.56.9819 1 COMPOSTING OF MUNICIPAL SOLID WASTE: AN EMPIRICAL ANALYSIS OF EXISTING PLANTS R. Gamberini, B. Rimini, P. Nicandri ABSTRACT. Thousands of tonnes of municipal solid waste (MSW) are produced every day, and consignment to landfill represents the most common disposal choice. However, sanitary problems and the increasing demand for dedicated spaces have directed the efforts of researchers and practitioners toward the study of alternative approaches to waste manage- ment. Composting is one possible way to treat the organic portion of MSW, and the efficient design and management of composting plants ensure that they are economically sustainable. Analyzing established or pioneering solutions allows guidelines to be drawn up for the design of new plants and/or the management of existing ones. In this article, a set of engineering indices for the technical and economic analysis of composting plants is first presented and then applied to data collected from ten existing plants, divided into two groups: plants mainly composting the organic fraction of house- hold solid waste with reduced levels of the organic fraction of agro-industrial waste, green waste, and sludge (Group A); and plants only composting green waste (Group B). For Group A plants, more complex technological solutions are re- quired, given the need to manage larger portions of untreated waste and leachate, along with odor problems. This means that the need for space (particularly covered space), facilities, operators, and initial investment is greater, and annual operating costs are higher. However, Group A plants can also charge more for processing waste. Keywords. Composting, Engineering indices, Municipal solid waste, MSW, Technical and economic analysis. housands of tonnes of municipal solid waste (MSW) are produced every day (e.g., about 90,000 tonnes per day in Italy in 2007), and land- fill often represents the most common disposal choice. As cited by Pognani et al. (2009), 67%, 69%, 61%, 63%, and 75% of the total MSW produced in Europe, Afri- ca, America, Asia, and Oceania, respectively, is assigned to landfill. However, some industrialized countries have re- cently passed laws to progressively reduce the portion of MSW assigned to landfill (such as European Council Di- rective 99/31/EC on the landfill of waste and its amending acts). This choice is driven by several motivations: the growing amount of space required (also difficult to find due to residents’ objections) and problems with unutilized me- thane production, insects and rodents, odors from volatile organic compounds, and leachate (Moldes et al., 2007). Composting, therefore, represents an alternative treatment for the organic portion of MSW (Ribeiro et al., 2000; Soumare et al., 2002). Published reports on composting mainly: (1) give details on the processing conditions required to ensure a good final product (Woodbury and Breslin, 1992; Ciavatta et al., 1993; Haug, 1993; Tuomela et al., 2000; Castaldi et al., 2005; Diaz et al., 2007; Smidt et al., 2008; Som et al., 2009; Rogger et al., 2010; Kranert et al., 2010; Raj and Antil, 2011); (2) discuss the effects of compost use on land (De- portes et al., 1995; Pichtel and Anderson, 1997; Adani et al., 2007, 2009; Eggerth et al., 2007; Wright et al., 2008; Aslam et al., 2008; Courtney and Mullen, 2008; Herrera et al., 2008); or (3) describe the facilities available for imple- menting the aforementioned chemical processes (Haug, 1993; Diaz et al., 2007; Kumar et al., 2009; Rasapoor et al., 2009; Maresova and Kollarova, 2010; Zhao et al., 2011). This article belongs to the third category. Specifically, it presents a set of engineering indices for the technical and economic analysis of established or pioneering composting technologies and applies them to data collected from ten well-performing composting plants. Like the work carried out by Kumar et al. (2009) on composting of household organic solid waste, this article aims to provide designers and managers a set of useful technical and economic engi- neering indices for industrial composting of the organic fraction of MSW. While such indices are available for other fields, e.g., ceramics (Gamberini and Regattieri, 2008), to the best of our knowledge they are not available in the lit- erature on composting plants. MATERIALS AND METHODS As mentioned above, the aim of this research is to de- velop a set of engineering indices to support designers and managers of composting plants. Data collected from exist- ing plants are presented and discussed in order to identify trends and develop a reference database for further studies. The engineering indices are calculated as follows: Submitted for review in June 2012 as manuscript number SE 9819; approved for publication by the Structures & Environment Division of ASABE in September 2013. The authors are Rita Gamberini, Researcher, Bianca Rimini, Full Professor and Paolo Nicandri, Post-Graduate Fellow, Department of Sciences and Methods for Engineering, University of Modena and Reggio Emilia, Reggio Emilia, Italy. Corresponding author: Rita Gamberini, Via Amendola 2, Padiglione Morselli, 42100 Reggio Emilia, Italy; phone: +0039-522-522633; e-mail: rita.gamberini@unimore.it. T