After completing these steps, which are aimed at separating the different materials from your raw waste and concentrating PET, the next step is pre-treatment (WP2); first at lab scale in this first period on highly technical PET fibers. This pretreatment phase is crucial for an efficient enzymatic depolymerization (WP3): to be accessible to the enzyme, specific to PET, the samples need to reach specifications on crystallinity and density levels. To achieve these goals on technical fibers, White Cycle (WP2) conducted numerous experiments to determine the most efficient pre-treatment techniques, comparing for example plasma, micronization, or thermal extrusion. Our findings at lab scale overwhelmingly favored extrusion, which also shows to be the most suitable in the scaling up process. Furthermore, these tests on pretreatment at lab scale significantly moved forward White Cycle expertise and understanding of contaminants’ impact in amorphization, such as rubber or cotton (WP2). This holistic approach not only ensures effective preparation of feedstocks but also contributes to the refinement of our knowledge base, enabling us to overcome technical challenges.
In White Cycle, the next phases in the recycling journey of PET complex fibers, are the enzymatic depolymerization and purification steps (WP3). The WP3 process involves purifying the resulting monomers, which can then be re-polymerized into high-quality PET, equivalent to virgin PET (WP4). In pursuit of making the multi layers and mixed feedstock accessible, , we conducted a series of experiments in WP1 and 2, yielding valuable insights. While our endeavors were met with excitement, we also encountered challenges in scaling up some sorting and pretreatment techniques, leading to their exclusion from consideration. Consequently, further investigations on complex textile are imperative at lab scale on pretreatment (WP2) to guarantee the success of the project. These ongoing efforts are essential for refining our approach and ensuring the effectiveness of the pretreatment phase, ultimately leading to an efficient enzymatic depolymerization (WP3).
