Absorbent hygiene products (AHP) is a broad category of products that includes baby nappies, sanitary protection pads, tampons, adult incontinence products and personal care wipes. Nowadays it is one of the most challenging types of post-consumer waste that are not recycled and usually disposed of via either landfill or incineration. AHP waste currently represent about 2-3% of the total municipal solid waste, and represent up to 15-25% of the residual waste stream in some treatment facilities, where selective collection rates above 70% are in place.
Public authorities and waste management organisations are aware of this issue and are starting to take action to support the recycling of this waste stream. The current best practice on this issue is focused on the treatment techniques available for the separation of the AHP waste into its different material components, which can be recycled into secondary raw materials (e.g. plastic, cellulose).
The core process is a thermal treatment in an autoclave, an horizontal cylindrical vessel where the AHP waste is sanitized and opened. The output solid stream is then shredded and separated through a mechanical process into the two AHP components: polypropylene and polyethylene plastics and cellulose fibres, which can be sent for recycling.
Available treatment technologies are able to recover 100 % of the original products of disposable nappies, i.e. 100 % of the plastics and 100 % of the cellulose fibres plus the super absorbent polymers (SAP) that are present in the AHP waste flow, considering the output of the nappy’s recycling process but not considering the residues resulting from the further sorting and industrial processing of these recovered materials. As cellulose and plastics used as raw materials for the production of AHP are high-quality materials, their recovery through treatment technologies provides the market with valuable secondary raw materials with multiple potential uses. The plastic is granulated and can be reused in several production cycles to make high-quality plastic goods or as an ingredient in composite materials replacing concrete and steel. The cellulose fibres can be used for the production of pet litter, pet care absorbent products, concrete and tarmac additives, brick manufacture, paper and cardboard, insulation materials and agricultural nutrients
The success of this best practice highly depends on the AHP waste collection system in place, people's participation, population density in the collection area, and the technical specifications of the treatment plant e.g. capacity. Moreover, the transport distance from collection areas to the treatment plant and costs for landfilling and incineration and criteria and rules for recognising the end of waste and local market for recovered materials are important factors that need to be deeply analysed before the implementation of the best practice.