Japanese researchers propose distributed microwave recycling for batteries

Researchers from Japan have developed a distributed recycling system that employs microwave-based heating for recycling old alkaline batteries. This process offers an efficient and cost-effective alternative for recycling e-waste at the local level.

Distributed recycling systems involving small-scale recycling facilities offer a sustainable alternative to conventional recycling systems. Such a system can greatly reduce the energy requirements for transportation and has the potential to increase recycling rates.

While this system is still in its infancy, many studies have explored its use in recycling plastics, photovoltaic waste, and wastewater, with particularly promising outcomes in distributed plastic recycling.

Distributed recycling

In a new study, researchers from Ritsumeikan University, Japan, proposed a new small-scale distributed recycling system for used batteries. “The feasibility to decentralize the recycling of e-waste needs to be analyzed, considering the different characteristics of each municipality. In this study, our focus is on obsolete alkaline batteries as waste product to be treated in a distributed recycling system,” explained Prof. Shoki Kosai, a member of the research team and the first author of the study.

Their new system employed microwave irradiation, which offers selective, rapid heating and reduced energy consumption compared to furnace-based heating. The team’s findings were published in the journal Resources, Environment and Sustainability.  

First, the researchers conducted an empirical study to explore the usability of this microwave-based technique in recycling spent alkaline batteries.

They then conducted an analytical case study to examine the effectiveness of distributed recycling systems in Japan. A total of 1,710 municipalities in Japan were considered in the study, which used energy consumption and greenhouse gas emissions as metrics for testing the effectiveness of the proposed recycling system. 

Microwave heating

The study showed that microwave-based heating achieved a recovery rate of 97% of manganese oxide and zinc from the alkaline batteries. This recovery rate is 1.5 times more than conventional electric furnace-based heating, and takes half the time.

The study also revealed that a balance between centralized and distributed recycling systems can reduce annual energy consumption and greenhouse gas emissions across Japan by 26,500 GJ and 1.54 Gg-CO2eq, respectively. 

The concept of decentralization is a new notion among recycling systems. In this regard, the findings of this study provide a good starting point to explore distributed recycling systems using microwave irradiation for metal recovery.

“Through the adoption of this system, areas where natural resources are not available will gain the opportunity to become suppliers of secondary resources. This system could also remedy the problem of metal recycling in developing countries,” Kosai concluded.