The RECALL nappy recycling technology has been developed by the Italian Company FATER SpA in the framework of the CIP Ecoinnovation RECALL project (RECALL, 2015; http://www.recall-ecoinnovation.eu/).
The post-consumer AHP waste is treated in a simple process: through the effect of steam and pressure in an autoclave, post-consumer AHP waste is sanitised, decomposed and dried, leading to the recovery of its valuable components (cellulose and plastic). The autoclave, which is the core of the plant, is a horizontal cylindrical vessel, which is heated by means of a jacket of saturated “no-contact” steam. The injection of another stream of “contact” steam provides the necessary sterilisation of the AHP waste, which is continuously mixed by the rotation and alternative oscillation of the vessel. The treatment scheme utilises methane from the grid to produce the steam necessary for the sterilisation process (Arena et al., 2016). Prior to entering the autoclave, AHP waste is stored within an air-controlled receiving bay, equipped with a biofilter and a leachate basin. The sanitised flow exiting the autoclave is shredded and mechanically treated for the recovery of cellulose fibre and plastic.
The recovery rate is almost equal to 100 % of the original fractions in the AHP, and the recovered fraction is of a high quality, because high-quality plastic and cellulose are used to manufacture nappies. From the evidence available, the recovery of about 146 kg of plastics and 345 kg of cellulose plus super absorbent polymers per tonne of AHP waste is observed, representing respectively 15 % and 35 % of the input flow, the rest being discharged process water sent to the treatment plant.
The outputs of the RECALL process are two high-quality reusable materials:
- plastic, which is extruded and takes the form of small beads and can be reused in several production cycles in a wider range of processes with no colouring issues;
- cellulose, which can be used for the production of absorbent products, pet litter, high-quality paper, chemical building blocks, agricultural nutrients and energy production via gasification.
The first RECALL treatment plant (8 000 t/year treatment capacity) was installed in 2015 within the recycling site of the public waste management company Contarina, located in Lovadina di Spresiano (TV), in the North-East of Italy. Currently it is authorised to operate as an experimental plant (Veneto Region, 2016) at a maximum capacity of 1 500 t/year. Further improvements to the recycling process are being implemented in order to optimise the plant efficiency (i.e. reduce energy consumption) and the quality of the recovered materials.
