Absorbent hygiene products (AHPs), including baby diapers, female pads and adult incontinence products, are essential to modern society. However, their increased usage has led to a significant environmental challenge. They account for approximately 3-4 % of municipal solid waste and are considered non-recyclable, typically ending up in landfills or incinerators.
A threefold approach to personal care waste management
'To tackle this issue, the CBE JU-funded EMBRACED project developed an innovative, first-of-its-kind integrated biorefinery model that turns AHP waste into valuable bio-based materials and products,' notes project partner Orsola Bolognani. This replicable, circular, economically viable and environmentally sustainable approach relies on three key aspects.
First, it transforms the cellulosic fraction of used AHPs to produce bio-based and biodegradable products. Second, it adopts a cascading approach where side streams from the bio-based processes are valorised to lower costs and improve environmental sustainability. Ultimately, it implements a circular economy approach, closing the cycle of raw materials and minimising the use of primary resources through collaboration amongst all stakeholders in the value chain.
Smart collection and pre-treatment solutions
Central to the success of this model is the separate collection of AHP waste from households and institutions. EMBRACED demonstrated the effectiveness of this concept through pilot testing campaigns in Amsterdam (the Netherlands), Paris (France) and Verona (Italy), using smart bins for household collection and an innovative direct-to-consumer service for healthcare facilities. Based on these campaigns, EMBRACED completed a scenario analysis for the logistics and plan required to collect the necessary feedstock for the biorefinery.
'The first step in the biorefinery process is mechanical pre-treatment, which recovers three separate high-purity fractions for further transformation: cellulose, plastic and superabsorbent polymer,' remarks Bolognani. EMBRACED successfully scaled up and adapted an existing pre-treatment plant and established a protocol for quality assurance of the material.
'EMBRACED successfully demonstrated the potential to convert previously non-recyclable, post-consumer absorvent hygiene product waste into valuable bio-based building blocks, materials and products with promising market trends.'
Project partner Orsola Bolognani
Converting AHP waste into eco-friendly plastics and fertilisers
Two innovative value chains were demonstrated within EMBRACED. 'Value chain A converts the cellulosic fraction recovered from AHP waste into sugars, which are then used to produce bio-based building blocks for biodegradable and compostable bioplastics,' explains Bolognani. These were validated for use in non-food packaging applications and mulch. Organic by-products and co-products generated during the process were successfully validated for biogas production via anaerobic digestion and to produce high-quality compost for soil improvement and regeneration.
'Value chain B also begins with the conversion of AHP waste cellulose into sugars but uses this feedstock in a biotechnological process for the production of polyhydroxybutyrate (PHB),' states Bolognani. This value chain has successfully evaluated the potential to convert co-products from the biotechnological process to formulate plant bio-based fertilisers and stimulants. Furthermore, PHB was assessed for possible use in medical applications and bio-based material development that capitalises on the biopolymer properties to improve biodegradation and disintegration rates.
'EMBRACED successfully demonstrated the potential to convert previously non-recyclable, post-consumer AHP waste into valuable bio-based building blocks, materials and products with promising market trends,' notes Bolognani.
The availability of AHP waste as a sustainable, locally sourced feedstock is especially crucial in the current economic climate, disrupted by the COVID-19 pandemic and geopolitical tensions. 'Despite challenges, such as varying energy costs and fragmented regulations, EMBRACED activities hold great promise for developing biorefineries in Europe,' concludes Bolognani.