Abstract
Objective. In this study, we discussed the evaluation method of mechanical recycling based on life cycle inventory analysis. CO2 reduction effect was considered as an example for the environmental burden of the evaluation and the method was applied to typical cases.
Results and Discussion. In case of closed-loop recycling, such as aluminum can recycling, three factors are important for the evaluation: the unit CO2 emission from the processes with and without recycling, and the recycling rate. Meanwhile, in case of open-loop (cascade) recycling, it is essential to make equal functional unit between the two scenarios. In this paper, we introduced performance ratio, which shows how much material is required to fulfill the defined unit function. Since a product from cascade recycling can be different from the corresponding original product in many aspects like as material composition, weight, and heating value, the CO2 emission may change depending on the subsequent processes like as waste treatment processes.
Conclusions. In each case of closed-loop recycling and cascade recycling, the CO2 reduction effect per recycling is key gauge. The discussions on evaluation method in this paper will contribute to know the points for an improvement in efficiency of mechanical recycling.
