Application of Life Cycle Assessment to chemical recycling of post-use glass containers on the laboratory scale towards circular economy implementation

Large quantities of post-use glass packages are produced globally, that so need to be treated as waste: this is cause of a global environmental concern. Therefore, efforts are required for optimisation and promotion of re-use and recycling practices with a waste valorisation-oriented approach in a circular economy context. In this context, the study was aimed at documenting environmental damages and improvements related to recycling glass cullet into sodium silicate in water solution on a lab-scale chemical process. Life Cycle Assessment was applied for this purpose according to the specialised International Standards. The study highlighted that the environmental hotspots of the process stay in the production of electricity and of sodium hydroxide as both required for the chemical reaction development. Those two input items contribute 81.94% and 14.33% of the total damage associated with the whole lab process, that is equal to nearly 36.5 μpt. A 64% environmental damage reduction could be obtained by sourcing the process electricity requirements by means of a photovoltaic plant. Furthermore, through a sensitivity analysis, the authors proved that the investigated sodium silicate is appreciably more environmentally sustainable than the virgin-origin counterpart, whose environmental profile was measured in nearly 43 μpt. The study can be considered as a proof that, already in the design phase on a lab-scale dimension, it is possible to identify recycling paths that may contribute to implementing sustainable circular models of the economy.