A method for recycling packaging wastes, referred to as first articles, made of PET or polyolefins (PO), that can be decolored in accordance with the key-locker principle, and second articles made of PET or PO, comprising the steps: (a) pre-sorting the first and second articles, (b) pre-washing the articles, (c) comminuting the articles to form flakes, (d) washing the articles, (e) dewatering and drying the flakes, (f) flake sorting, (g) extrusion, (h) solid-state polycondensation (SSP) in the case of PET wastes, or (i) decontamination in the case of PO wastes. The first articles are separated from the second articles by optical sorting and are decolored separate from the second articles in a decoloring step (j) by a reagent referred to as a key. The first decolored articles are temporarily stored (m) after step (j). After being stored, the first articles are fed to separate steps (g) and (h) or (i).

The method of uniquely identifying a product for subsequent recycling includes marking a surface of the product with a first trace signature being representative of the manufacturer of the product.

A plastic item, such as a beverage bottle, conveys two distinct digital watermarks, encoded using two distinct signaling protocols. A first, printed label watermark conveys a retailing payload, including a Global Trade Item Number (GTIN) used by a point-of-sale scanner in a retail store to identify and price the item when presented for checkout. A second, plastic texture watermark conveys a recycling payload, including data identifying the composition of the plastic. The use of two different signaling protocols assures that a point-of-sale scanner will not spend its limited time and computational resources working to decode the recycling watermark, which lacks the data needed for retail checkout. In some embodiments, a recycling apparatus makes advantageous use of both types of watermarks to identify the plastic composition of the item (e.g., relating GTIN to plastic type using an associated database), thereby increasing the fraction of items that are correctly identified for sorting and recycling. A great number of other features and arrangements are also detailed.

A computer-implemented method can be used for controlling sorting of plastic compounds. The method involves providing a computer-based database containing entries on a plurality of markers each identifying a specific plastic compound; receiving scan data from a sample of a plastic compound; identifying a marker in the sample of the plastic compound based on the received scan data and the plurality of markers of the database; and sorting of plastic compounds based on the identified marker of the sample of the plastic compound.

The invention comprises methods of robotically separating unwanted heteroatom-containing materials from a plastic mixture and catalytically pyrolyzing the resulting mixed plastics to obtain olefins and aromatics. Systems and compositions useful in the catalytic pyrolysis of plastics are also described.

A pelletizing apparatus includes a filter device connected with a melt feed, a granulator downstream of the filter device, particularly an underwater granulator, a water treatment device, and a control means for controlling the filter device, underwater granulator, and water treatment device and adapted to provide at least one control parameter. The apparatus includes at least one machine-readable and -writable identification means for storing and providing an item of component-specific information and being associated with a component in the flow path of the melt or the process water, and a reading device communicating with the control means to receive the component-specific information from the identification means, and a writing device to write the identification means with the component-specific information, the control means to adapt the control parameter based on the component-specific information to provide the component-specific information, and, based on the component-specific information, to execute a diagnostic process.

Methods of enriching plastic items from a composition comprising one, or different types of plastic comprising the steps of: labelling the one or different types of plastics in said composition with one or more molecules that are fluorescent and/or absorb light in the ultraviolet, visible or near-infrared range, enriching one or more types of plastic from said composition based on the resulting fluoresce and/or absorbance properties of the labelled plastics.

A pelletizing apparatus includes a filter device connected with a melt feed, a granulator downstream of the filter device, particularly an underwater granulator, a water treatment device, and a control means for controlling the filter device, underwater granulator, and water treatment device and adapted to provide at least one control parameter. The apparatus includes at least one machine-readable and -writable identification means for storing and providing an item of component-specific information and being associated with a component in the flow path of the melt or the process water, and a reading device communicating with the control means to receive the component-specific information from the identification means, and a writing device to write the identification means with the component-specific information, the control means to adapt the control parameter based on the component-specific information to provide the component-specific information, and, based on the component-specific information, to execute a diagnostic process.

A pelletizing apparatus includes a filter device connected with a melt feed, a granulator downstream of the filter device, particularly an underwater granulator, a water treatment device, and a control means for controlling the filter device, underwater granulator, and water treatment device and adapted to provide at least one control parameter. The apparatus includes at least one machine-readable and -writable identification means for storing and providing an item of component-specific information and being associated with a component in the flow path of the melt or the process water, and a reading device communicating with the control means to receive the component-specific information from the identification means, and a writing device to write the identification means with the component-specific information, the control means to adapt the control parameter based on the component-specific information to provide the component-specific information, and, based on the component-specific information, to execute a diagnostic process.

The invention comprises methods of robotically separating unwanted heteroatom-containing materials from a plastic mixture and catalytically pyrolyzing the resulting mixed plastics to obtain olefins and aromatics. Systems and compositions useful in the catalytic pyrolysis of plastics are also described.