Comparative LCA between anaerobic co-digestion of organic fraction of MSW and treated sludge, and the actuale management system adopted in a small Italian town

The waste production represents, undoubtedly, one of the most important evironmental emergencies that need to be solved, on the global level. Furthermore, it tends to increase due to the rise of the population. Nowadays, the traditional management strategies result to be unsatisfactory. We need updated tools, functional to the contexts in which they are developed. The idea of recovering energy from waste, with incineration for example, or the idea of saving it, with waste reutilization or recycling processes, has been realized for many years. In relation to this, the present study aims to compare the actual management system (in a small province), concerning the organic fraction of municipal solid waste (OFMSW) and the dewatered sludge (DS), with an alternative recovery project for the two fractions using LCA as a tool of environmental analysis. The project is named “For Biogas” and consists of a plant that receives the DS, from both urban and agro-industrial sewage, and the OFMSW which are digested (in 1/1 ratio) in absence of oxygen to produce biogas and digestate. Biogas is piped to a co-generation system that produces power and heat reused in the digestion process itself, making it independent from the national grid. Digestate undergoes a process of mechanical separation that produces a liquid fraction, introduced in the treatment plant, and a solid fraction disposed in a landfill (in future processed further to obtain compost). Actual scenario treats the two fractions separately: the organic one is sent to the composting plant, while sludge is sent to the landfill.