Urban biowaste
Urban biowaste is the main feedstock for the SOWISE+ PHBV production line. The flagship is designed to process approximately 39 tonnes of biowaste per day, corresponding to around 16.500 tonnes per year. This represents roughly one third of the biowaste available within Contarina's service area, which covers a population of approximately 560,000 inhabitants.
Instead of treating this organic fraction only through conventional recovery routes, SOWISE+ introduces an additional high-value step: part of the organic matter is converted into intermediates that microorganisms can use to accumulate PHBV. The resulting polymer can then be recovered, purified and used as a raw material for new bio-based products.
The use of a real municipal waste stream is particularly important for the project, as the composition of urban biowaste can vary over time. SOWISE+ will therefore assess feedstock characteristics and use monitoring and process-control tools to support reliable industrial operation under changing conditions.
Post-consumer
absorbent hygiene
products (AHP)
The second key raw material is post-consumer absorbent hygiene product waste, or AHP waste. This category includes used products containing significant quantities of cellulose together with plastics and superabsorbent polymers.
From waste streams
to secondary raw
materials
By combining these two pathways, SOWISE+ demonstrates a cascading approach to urban waste valorisation. Rather than viewing and used AHPs simply as materials requiring treatment, the project treats them as potential sources of PHBV and high-quality cellulose.
These recovered resources will subsequently be used to develop and validate new materials for applications including packaging, agriculture, healthcare-related products, construction materials and composites.
The associated Contarina recycling facility is designed to treat up to 5,000 tonnes of post-consumer AHPs per year, or approximately 14 tonnes per day. The primary recycling process separates the different material fractions, while the SOWISE+ add-on line focuses specifically on further purifying and upgrading the recovered cellulose.
Through additional separation, cleaning and conditioning steps, SOWISE+ aims to substantially reduce residual superabsorbent polymer and plastic contamination and produce cellulose suitable for higher-value applications.