A process known in Japan as "horizontal recycling" is gaining a foothold, with the practice able to contribute to a more sustainable society while addressing the nation's plastic addiction.

Horizontal recycling refers to recovering and processing used products into raw materials to be used to reproduce the original item.

For example, although most used plastic bottles are collected and recycled into fiber and other items, such as food trays, beverage manufacturers are now focusing on recycling them into new plastic bottles.

Household detergent products, mostly refill packs rather than bottles, fill the shelves at Consumers Co-operative Kobe's "Co-op Rokko" in Kobe, as seen in February 2023. (Kyodo)

But the horizontal recycling movement is expanding beyond that to include refill packs for daily use products like shampoo and dishwashing liquid. By promoting the process, used plastic bottles and other items can be repeatedly recycled into the same thing without the need for new petroleum-derived materials.

The recycling of plastics in Japan can be broadly classified into two categories: material recycling, in which waste is converted to raw materials for new products, and chemical recycling, in which waste is chemically decomposed into other substances and used as raw materials to make new products.

Plastics are also processed along with other waste via thermal recovery, which involves utilizing heat generated when trash is incinerated.

Horizontal recycling falls under the category of material recycling.

Kao's prototype of recycled refill pack (top L) and other items are pictured in Tokyo in February 2023. (Kyodo)

In October 2021, the municipal government of Kobe in Hyogo Prefecture, western Japan, together with 16 manufacturers of daily-use articles, retailers and recycling companies, launched the "Kobe Plastic Next" initiative aimed at providing collection points for refill packaging from detergent, shampoos and other items at 75 retail locations.

Among the participants are companies such as cosmetics giants Kao Corp. and Lion Corp. and pharmaceutical firm Earth Corp.

Having since added two more participants and three more recycling locations, the project brings together rival companies for the common good.

Refill packaging uses 70-80 percent less plastic than the bottles in which the respective products are traditionally sold. Used widely in Japan, the refill packs significantly cut plastic waste generation.

According to the Japan Soap and Detergent Association, some 80 percent of daily-use articles are shipped in refill packs in Japan and more refill packs than bottled containers fill the household detergent aisles at many stores.

Project leader Keiji Seto of Kao's Research and Development Division is pictured during an interview in front of a prototype made from recycled refill packs (back L), and other products in Tokyo in February 2023. (Kyodo)

Even so, the film used for the packs is difficult to recycle due to its multi-layered structure made of composite materials, and in many cases, it is treated as burnable waste.

Under such circumstances, the Kobe city office thought of somehow recycling the refill packs "by aiming to return them to the same object using high-level horizontal recycling," Mitsunori Shimizu, a city official in charge, said.

Kao, which sells large quantities of refill packs, participated in the project out of a fear that such containers if deemed unsuitable to a recycling-oriented society, "could be subject to restrictions or even seen as 'evil,'" said Keiji Seto of the research and development section at the Tokyo-based company.

At its research center in Wakayama, Kao project leader Seto and his team are devising technology to crush collected refill packs into pellets, which are then converted into film and remade into refill packs.

"We found it was possible that products from all the project participants could be used to make film for use in recycled packs," Seto said, adding that Kao plans to roll out recycled refill packs for general consumer use by 2025.

Kobe collected 1.13 tons of refill packs in one year.

A refill pack collection box at Consumers Co-operative Kobe's "Co-op Rokko" store in Kobe is pictured in February 2023. (Kyodo)

Kiyotake Matsui, assigned to promote sustainable development goals, or SDGs, at Consumers Co-operative Kobe, which has installed recycling bins at its stores, said, "There is a need as we see that some stores are collecting more refill packs than expected."

The city will aim to collect 5 tons of refill packs a year to achieve its horizontal recycling goal ahead of schedule to move Japan a step closer toward decarbonization.

With inquiries about the project coming into the city and project participants from other local governments and entities, expectations are high that the horizontal recycling initiative will spread nationwide before long.

According to Toyota Tsusho Corp., whose subsidiary last October opened a horizontal recycling factory in Hino, Shiga Prefecture, Japan recovers about 97 percent of its plastic bottles.

But of the approximately 290,000 tons recycled, roughly 70 percent are processed into food trays, car interior materials, among other objects, and ultimately incinerated.