Assessment of organic waste management methods through energy balance

Abstract

In Italy, the Organic Fraction of Municipal Solid Waste (OFMSW) is nowadays landfilled or processed through aerobic composting. The Italian towns currently support a high cost for OFMSW disposal and cause a high environmental impact, because of long distances travelled from towns to a few available landfills and fewer treatment places, as well as the used waste management methods. An interesting option for OFMSW is Anaerobic Digestion (AD), producing biogas and “digestate”. In this survey a theoretical biogas plant was placed near a town of Sicily Region (Italy), centralised with reference to the area considered for producing OFMSW. The distances travelled every year to transport OFMSW from the nine towns considered to the nearest composting plant and the biogas one were calculated using QGIS software. Therefore, the energy balance was computed for each of the four considered scenarios. Within the implementation of Integrated Solid Waste Management (ISWM) method, AD resulted in an energy balance much higher than that of aerobic composting. In fact, differently from composting, AD can significantly contribute to energy recovery, while retaining the nutrients in the digestate produced and reducing Greenhouse Gas (GHG) emissions. The use of a rational network of towns for OFMSW collection and transportation results relevant, in terms of increased energy balance, only in the case of composting. Therefore, if AD would be implemented as OFMSW management method, by means of biogas plants, each of them placed in an area including some towns, e.g. that considered in this survey, it could highly reduce the cost and the environmental impact of waste disposal.