The application of LCA to alternative methods for treating the organic fiber produced from autoclaving unsorted municipal solid waste: case study of Catalonia

Despite efforts to increase the selective collection of municipal solid waste (MSW) in developed countries, the amount of unsorted waste remains high, with the consequent difficulty of material recovery and recycling. In 2010, 61% of the MSW generated in the European Union (EU) ended up in landfill and incineration facilities. Autoclaving is a novel technology that can be used to treat unsorted MSW, producing organic fibers that can be composted. The life cycle analysis (LCA) was used to assess the effectiveness of autoclaving unsorted MSW and various alternative methods for treating organic fibers produced through this process. The alternative methods that were considered included composting in tunnels, composting in confined windrow and composting in turning windrow as well as anaerobic digestion. The environmental assessment results were compared to those associated with incineration and landfill. The results of this study showed that autoclaving with sorting, digesting anaerobically and composting had the lowest impact values for eutrophication and the global warming potential. It was also found that autoclaving is justified only if the products of the process, that is, polyethylene terephthalate, ferrous and non-ferrous metals, are recycled to avoid virgin material production and if the remaining mixed plastic wastes are incinerated for energy recovery.