## 2 A Case Study for the MSW Management of the Procida Island
### Life Cycle Impact Assessment  
Data reported in the LCI section were used as input to the life-cycle impact assessment (LCIA) stage, which quantifies the potential impacts related to the main midpoint categories, those of global warming (GW), non-carcinogens (NC), respiratory inorganics (RI), non-renewable energy (NRE), and land occupation (LO). Figure 5 reports the normalized results (expressed as \"person*year\", i.e., the average impact in a specific category caused by a person during one year in Europe), to enable comparison of data related to different impact categories.  
Data indicate that the evolution of MSW management in Procida was very positive. All the contributions to impact assessment in 2021 were negative, i.e., they positively affected the environment. The potential impact of GW improved by 140%, moving from 0.005 to \(-\)0.002 person*year, mainly due to the alternative management option adopted for the separately collected organic fraction and to the increased quantity of materials sent to recycling. The implementation of anaerobic digestion in place of a composting process led to better performances due to the impacts avoided resulting from obtained energy recovery. The increased amounts of glass, metals, plastics, and paper sent to recycling imply greater benefits related to the avoided production of virgin materials. The increased amount of glass sent to recycling (from 45 kg to 95 kg for FU) was the main difference between the two scenarios, resulting in an improvement for GW. On the other hand, the direct impacts of plastics recycling were higher than the avoided impacts. This is explained by the increased necessity of thermal treatment for the residues coming from the sorting stages, which amounted to about 50% of the separately collected plastics (as shown in ANNEX C) and were largely composed of plastic waste not suitable for mechanical recycling. On the other hand, the higher quantity of plastics sent to recycling (from 18 kg to 36 kg for FU), together with the implementation of anaerobic digestion of the MSW organic fraction, improved the NRE potential by 56%, due to the avoided consumption of fossil resources. The higher amount of paper sent to recycling (from 75 kg to 104 kg for FU) was the main contributor to improvement of the LO category (of about 16%) due to the avoided production of virgin paper. Categories connected to human health were also remarkably enhanced. RI improved by 47%, from \(-\)0.021 to \(-\)0.031 person*year, again with a primary contribution of recycling chains. NC improved by 143%, from +0.008 to \(-\)0.003 person*year, due to the alternative management option for bottom ashes (recovery of inert and metals instead of  
Figure 4: Comparisons between amounts of separately collected waste streams in Procida in 2011 and 2021 (**left**), and amounts sent to thermal treatments or disposal in landfill in the same years (**right**). Data source: W-MySir [7].  
landfill disposal). Transportation had a limited effect on the GW, NRE and RI categories, even though it showed improved performances for 2021 related to the adoption of a more modern vehicle fleet (use of Euro 6 trucks instead of Euro 3 trucks).