Additional steps in mechanical recyling of PET

This study presents the laboratory scale results of an extra step in Poly (ethylene terephthalate) – PET mechanical recycling (grinding, washing, drying and reprocessing): a chemical washing after the conventional one. Cooking oil PET bottle flakes were washed in water and then subjected to a reaction with an aqueous solution of sodium hydroxide 5 M at 90 °C for 10 min (chemical washing). After rinsing and drying, the flakes were characterized by thermogravimetry, gas chromatography and elemental analysis tests. The results indicated that the chemically washed material had higher purity than PET washed only with water: 99.3% and 96.7%, respectively, which undoubtedly implies properties, applications and prices closer to those of virgin resin. The production of purified terephthalic acid (TPA) from the chemical washing residue was optimized and reached a purity of 99.6%. Despite the results, the use of chemically washed PET and of TPA obtained is not recommended for direct contact with food, since they still contain some impurities.     

From green product definitions and classifications to the Green Option Matrix

Hybrid cars, recycled products, photovoltaic cells, bioplastics: why so different products can be called ‘green’? Which practices companies willing to develop green products should implement? How companies can easily and effectively communicate to stakeholders the environmental features of their green products? This paper tries to answer these questions, by developing a Green Option Matrix (GOM), which characterizes green products and practices along different dimensions. This matrix is then used to analyze the different features of green products as well as related green practices developed by a sample of companies belonging to the Dow Jones Sustainability World Index (DJSWI). Relevant data are collected by means of content analysis of companies’ websites and sustainability reports. Green products and practices developed by each company in the sample are positioned in the matrix and results are presented and discussed for each industrial sector. Then, different sectors’ behaviors are compared. The proposed matrix can be used by companies as a market tool to analyze competitors’ green products and practices and as a communication tool to effectively communicate to stakeholders the specific green features of their products and practices.     

Revisiting the Life Cycle Assessment of mussels from a sectorial perspective

Mussels as a commercial product involve a range of activities which can be included within four different sub-sectors: culture, dispatch centres, canning factories and, finally, cooking plants. This paper deals with the environmental evaluation of the whole mussel sector from a Life Cycle Assessment approach. The use of exhaustive inventories led to the subsequent environmental characterization of the mussel sector in terms of the contribution observed for each of the sub-sectors. In this sense, the sub-sector associated with dispatch centres presented the largest contributions to the potential environmental impacts, clearly ahead of mussel farming. Furthermore, the sub-sectors of mussel cooking plants and canning factories showed a much lower contribution to the potential environmental impacts. Several improvement potentials were identified from the characterization results, stressing the minimization of the electric energy consumption in dispatch centres. A comparative LCA was performed in order to contrast the environmental performance of the three main commercial mussel products: fresh mussels, canned mussels and frozen mussels. The analysis showed that fresh mussels have the least favourable environmental profile.