Disposable baby diapers are a challenging waste stream, because the absorbent polymers, non-woven fibers and organic material prevent them from mechanical-recycling processes. However, a three-way partnership has demonstrated a circular system for chemical recycling of disposable diapers. The project, involving the Belgium-based diaper company Woosh (Ghent, Belgium; www.woosh.care), the polyolefin maker Borouge International (Vienna, Austria; www.borougeinternational.com) and the plastics recycler BlueAlp (Eindhoven, the Netherlands; www.bluealp.nl), chemically recycles materials from the used diapers into feedstock for new polymers.
Woosh designed its “give-back diapers” for recyclability, using only polypropylene and polyethylene where possible and excluding materials that would disrupt the recycling process or contaminate the output. This means no cotton, bamboo or other natural fibers embedded in the non-woven layers, and no polyester or polylactic acid (PLA) components, which are not easily recycled together with polyolefins. Currently, parts that cannot be recycled are handled through conventional waste treatment, but Woosh is working on solutions to increase the share of materials that can be recovered.
Woosh has also set up a program where the company supplies diapers to childcare facilities and households and collects them again after use, creating a separate, traceable stream of used diapers for recycling.
Borouge and BlueAlp worked with Woosh engineers to define the quality requirements the recovered plastic needed to meet to be used as input for BlueAlp’s chemical recycling technology. Woosh then optimized its proprietary mechanical-separation process to produce plastic fractions that meet these requirements, the companies say.
The used and collected diapers are now being recycled at a BlueAlp facility in Oostende, Belgium. BlueAlp’s pyrolysis recycling process is designed for low-temperature chemical recycling of mixed plastic waste. The BlueAlp process requires less energy and less gas and it produces more oil overall and more oil of high quality, says BlueAlp CEO Valentijn de Neve. “We have a continuous process, which means more efficient use of reactors, and more stability, making it easier to operate,” explains de Neve. “It also means less energy, by avoiding frequent heating and cooling cycles.”
BlueAlp’s pyrolysis oil is certified to International Sustainability & Carbon Certification (ISCC)-PLUS specifications, a globally recognized sustainability certification for bio-based, renewable and circular (recycled) raw materials, and meets the required quality specifications for further processing into new polymers, including those suitable for new diaper production.
Woosh plans to expand its model into France and the Netherlands, increasing the volume of recovered plastic available for recycling.