Youtube Facebook Linkedin Instagram Comment-dots
Search

Diaper recycling – enzymatic circular solutions for hygiene waste

Back of a baby and a stuffed teddy bear in nappies
Picture: Shutterstock

Initial pilot trials confirm both technical feasibility and process stability. In the next steps, the individual modules will be further optimized, scaled up, and advanced to higher technology readiness levels. In parallel, strategic partnerships with healthcare institutions, technology providers, and regulatory stakeholders are planned to pave the way toward practical implementation. "Diapers Recycler" compellingly demonstrates how biotechnological innovation and the circular economy can jointly create new solutions for waste problems that have remained unsolved to date.

Used diapers are among the most problematic waste streams in the healthcare and care sector. Due to their high moisture content, biological contamination, and composite material structure, they have so far been regarded as non-recyclable and are predominantly incinerated or landfilled. This results in high transport efforts, costs, and environmental impacts-particularly in hospitals, care facilities, and childcare institutions that generate large volumes of waste. The “Diapers Recycler” project pursues a novel approach: instead of centralized disposal, a modular system designed for decentralized use enables the treatment and material recovery of diaper waste directly on site. The objective was to preserve valuable material fractions, reduce transport distances, and integrate hygiene waste into a functioning circular economy process for the first time.

Technological Innovation

At the core of the system is an enzyme-based cleaning process that gently removes organic contaminants such as faeces and urine without damaging the structure of the contained materials. The enzymes used are not industrially purchased but are sustainably produced through the fermentation of fruit and vegetable residues.
Microorganisms such as Bacillus subtilis and Saccharomyces cerevisiae are employed, producing enzyme mixtures with protease, cellulase, amylase, and esterase activity. This approach combines waste treatment with bioeconomy and resource recovery while simultaneously reducing overall resource consumption.

Results and Recoverable Output Streams

Following enzymatic cleaning, three high value material fractions were successfully recovered:
  • Superabsorbent polymer (SAP): The superabsorbent polymer was separated and purified. Functional tests demonstrated that the material retains its absorption capacity over at least six reuse cycles.
  • Plastic fraction: Plastics such as PET, PP, and PE were manually separated and processed to a quality suitable for recycling or further material reuse.
  • Organic fraction: The cellulose containing components were enzymatically converted into fermentable sugars-providing a valuable basis for biotechnological applications. Remaining organic matter was subjected to anaerobic digestion, achieving a methane yield of 34.87 NmL CH4 per gram of input material, while complying with regulatory nitrogen limit values.
Accompanying analyses also showed a significant reduction in turbidity, protein content, and total carbon in the process water, clearly demonstrating the effectiveness of the cleaning process.

Impact and Benefits

The Diapers Recycler represents a paradigm shift in the management of hygiene waste. The project demonstrates for the first time that even highly contaminated waste streams can be treated in a material preserving manner and integrated into value added material cycles. The benefits are manifold:
  • Reduction of transport effort and CO2 emissions
  • Recovery of valuable raw materials
  • Use of food waste as a resource (e.g. fruit peels, vegetable scraps)
  • Potential cost advantages through decentralized processing
  • High transferability to healthcare and care infrastructure
Initial pilot trials confirm both technical feasibility and process stability. In the next steps, the individual modules will be further optimized, scaled up, and advanced to higher technology readiness levels. In parallel, strategic partnerships with healthcare institutions, technology providers, and regulatory stakeholders are planned to pave the way toward practical implementation. “Diapers Recycler” compellingly demonstrates how biotechnological innovation and the circular economy can jointly create new solutions for waste problems that have remained unsolved to date.

Kontakt

Dr. Sara Vecchiato
Senior Researcher