Recycling portable alkaline/ZnC batteries for a circular economy: An assessment of natural resource consumption from a life cycle and criticality perspective

It has been recognized that a proper and sustainable management strategy might help prevent the risks of leaching from waste portable batteries (WPBs), which are an important waste stream, and aid the conservation of raw materials. Unlike existing studies on WPB management, which focus mainly on emissions, this case study uses a resource-oriented approach to thoroughly analyze the performance of a WPB collection and recycling scheme. This study focused on the WPB take-back and recycling system managed by Bebat in Belgium. Life cycle assessment was conducted using three different existing life cycle impact assessment (LCIA) methods representing three different perspectives: Cumulative Exergy Extracted from the Natural Environment; Abiotic Depletion Potential (ADP), split into impact categories called ADPelements and ADPfossilfuels; and damage to Resource Cost. A new LCIA method, the criticality-based impact assessment method, has also been introduced to cover the socioeconomic aspects of natural resource consumption. The performance of the mixed waste (i.e., batteries, flashlights) collection and sorting system was assessed from 2011 to 2013. This analysis showed that in 2012, the use of collection receptacles made of plastic bags with 30% recycled content, instead of non-recycled paper or cardboard with 30% recycled content, was one of the main reasons for the low impact of the whole system from all assessment perspectives. The performance of entire take-back and recycling system for alkaline and zinc-carbon (ZnC) batteries, the two most popular portable batteries, was subsequently analyzed and benchmarked against two incineration scenarios: with and without bottom ash recovery. The comparisons of the four LCIA methods show differing results. The most prominent result is that the ADPelements score of the recycling scenario is 7–9 times lower than that of the incineration scenario, mainly due to metals (i.e., iron and zinc) savings via recycling. The recycling system requires 17–52% less material criticality, but extracts 13–18% more exergy from the natural environment and has a higher ADPfossilfuels score (about 14–16%) than the incineration system. These comparisons indicate that although the alkaline/ZnC battery management system run by Bebat does not reduce consumption of all resources, especially fossil fuels and land, it is beneficial in terms of minerals and metals savings. To further improve the efficiency and environmental performance of the collection system, different measures were implemented. A sensitivity analysis was performed to evaluate the impacts of those measures on the mixed waste collection and sorting system and the alkaline/ZnC battery take-back and recycling system. The results suggested that a combination of different measures, especially reducing the number of receptacles used and enhancing their environmental performance, can considerably reduce the resource footprint.