In recent years, diaper waste has received a lot of attention due to the high volume produced and the difficulty in recycling. In fact, in the European Union, the annual market demand for disposable baby diapers exceeds 20 billion units, dramatically increasing the amount of dry weight waste (1.3 t/min). Despite their high value components, especially the super-absorbent polymer, these waste diapers are mostly disposed through incineration or buried in landfills.
Lately, some processes have been developed to mechanically recycle the different diaper components. However, these methods have issues in the complete separation of all the components, preventing the recovery of highly pure materials. Due to its composition, waste diapers can be potential substrates for enzymatic recycling, to recover the valuable components without worsening the current landfills situation. By using different enzymatic strategies, environmentally sustainable treatment of waste diapers can be carried out for a complete circular economy solution.
Diapers and other Absorbent Hygiene Products (AHPs) are mainly composed of a mix of polymers (superabsorbent polymers and PP/PE) and natural fibres (cellulose). Existing technologies have been developed to sterilise, dry and separate the AHPs into their constituent parts. However, these separated component streams are typically contaminated and not pure.
This technology thus proposes the use of advanced enzymatic processes for the degradation in mild conditions of various synthetic and bio-based polymers, and cellulosic fractions into their building blocks. With different enzymes, due to their specificity, it is also possible to fully degrade composite materials consisting of e.g. PET (polyethylene terephthalate), cellulose, etc. It is even possible to identify novel enzymes for specific industrial applications.
Furthermore, sustainable processes have been developed for the re-use of recovered valuable molecules. Recovered sugars can be used to perform different fermentation processes for the production of e.g. bioethanol, lactic acid, etc. The recovered building blocks can be used in chemical synthesis and can be re-used as secondary raw materials. These activities make use of the latest biotechnology tools and sophisticated analytical equipment as well as facilities for scale-up.
This technology may be applied in the following applications:
The enzymatic method of recycling allows for users to degrade specific materials within a composite, and degrade them to their chemical building blocks. This enables the recovery of specific component material of the diapers/AHPs in a much purer form, allowing the recovered material to be used in a wider range of applications.