Report End of Life for
Report End of Life for PLA Egg-Carton In a study performed by JBA (the Japan Bioindustry Association) different end-of-life options based on the ecological and economical profile of food containers made from biomass-based plastics (BP) were investigated. It was found that conversion into so-called Refused Paper and Plastic Fuel (RPF) could be one of the most ‘realistic’ recycling treatments. The following end-of-life or recovery options respectively were studied and compared: • RPF, Reused Paper and Plastic Fuel (RPF is a high quality solid fuel using non-reclaimable used paper and plastic waste as raw materials, in high demand from the steel, paper, lime and many other industries as an alternative to fossil fuels such as coal, coke and oil) • Mechanical Recycling (consisting of collecting, grinding, cleaning and reprocessing in an extrusion process into pellets) • Chemical Recycling, i.e. converting the material back into its monomers or oligomers with subsequent repolymerization • Biological Recycling - here composting in an industrial composting plant • Thermal Recycling, i.e. incineration with energy recovery, also sometimes referred to as Waste-to-Energy Experimental Scheme End-of-Life options of biomass-based containers for chickens’ eggs (Fig 1) thermoformed from Ingeo PLA sheet (NatureWorks) were examined. Between 200 and 300 containers per day, each for 10 eggs from one of the major Japanese retailers were collected by consumers in specified boxes put near the entrance of the store. The experiment was carried out between October 1, 2007 and March 31, 2010 and was financially supported by MAFF, the Ministry of Agriculture, Forestry and Fishery, of the Japanese Government. Recovery The recovery rate of used PLA egg containers during the experiment was about 9.9% in one of the stores located in an area working keenly on environmental conservation, whereas only 2.9% was observed in another store in an area not very much encouraging recycling of plastic products. Chemical Recycling For another fraction of the collected PLA egg containers chemical recycling was performed. Here the PLA is converted into lactide oligomers by hydration induced by super heated steam and then to repolymerized into PLA. This PLA was again molded to the same egg containers, and again thermal recycling was applied after the second use. Biological Recycling The bio-recycling i.e. composting was also tried to a third fraction of the collected containers. . Refuse Paper & Plastic Fuel And finally the RPF (Refuse Paper & Plastic Fuel) was also tried. Results For all recycling processes Greenhouse Gas (GHG) emissions and Life-Cycle Cost (LCC) were determined. GHG and LCC for the PLA containers from the cultivation of the biomass resources through to the final waste-toenergy incineration for the different recycling options were estimated. Hereby all transports to and within Japan were taken into account. GHG and LCC estimates for each option were compared. Mechanical and chemical recycling showed a better ecological performance whereas their LCCs were approximately double compared to thermal recycling, RPF or biological recycling. In other words, although the GHGs of RPF and composting are slightly higher than those of mechanical or chemical recycling, their LCCs are almost the same as with thermal recyling. As a conclusion, RPF or composting can be ‘cost-effective’ ecological end-of-life scenarios. In Japan however, where biological recycling or composting is not widely developed in or near the large cities, RPF can be one of the more feasible options for the PLA containers after use. In the experiment. Further quantitative analysis, including effects of recovery of the containers made from oilbased PET, has been also been carried out. Mechanical Recycling For some of the used PLA egg containers mechanical recycling was applied. As the remelting and thermoforming process allows converting without hygiene problems the recycled material was used again to make food containers. These products were again used in the stores, and after the second use, were incinerated with energy recovery (thermal recycling). By Kazushi, Ohshima JBA, Japan Bioindustry Association Tokyo, Japan www.jba.or.jp 22 bioplastics MAGAZINE [03/11] Vol. 6
ioplastics MAGAZINE [03/11] Vol. 6 23
