Plastic (PET) vs bioplastic (PLA) or refillable aluminium bottles - What is the most sustainable choice for drinking water? A life-cycle (LCA) analysis

摘要

Nowadays, the most important tool to evaluate the environmental impact of both petro-plastics and bioplastics is the life cycle analysis (LCA). LCA determines the overall impact on the environment by defining, calculation and analyzing all the input and output directly related to production, utilization, and disposal of a product or a process. In this work, a LCA (cradle to grave) of bottles for drinking water was developed on three scenarios: polyethylene terephthalate (PET) bottles, as conventional packaging material for outdoor drinking water, pol-ylactic acid (PLA) bottles, as alternative and innovative biodegradable packaging and aluminum bottle, as reusable and almost infinitely refilling packaging. As a result of LCA, ten impacts categories have been accounted for, among which the global warming potential (GWP, measured as kgCO_2 eq), the eutrophication potential (EP, measured as kgPO_4 eq.), human and eco-toxicity (HTP and ETP, measured as kg 1,4-DB eq.). The average drinking water consumption in Italy has been estimated in 1.5 L per day, corresponding to three 500 ml-plastic bottles and 1 refillable aluminum bottle. LCA has been firstly applied to a single bottle production and use, then to the daily and annual bottles consumption. PET bottles production and use assure the lower environmental impacts compared to PLA bottles, burdened by agricultural phase for corn cultivation, and to aluminum bottles, when the every-day washing with hot water or water and soap is comprehended. Moreover, including the end-of-life options into the analysis, PET recycling permits to reduce up to about 30% the GWP, whereas PLA composting does not lead to any GWP savings. In this study, aluminum bottle has been considered reusable for 2.5 years. The microbiological quality of water in one-way PET and PLA bottles has been compared with the refillable bottle rinsing with hot water and soap and only hot water, highlighting that the level of contamination is alarmingly increased in the latter case.