Advanced recycling provides solutions for plastic waste management. With advanced recycling technologies, plastics can be converted into new base materials to reduce or eliminate the need for virgin feedstock.
Many states are already enacting bans on plastic bags, marking a tangible move to a more Earth-friendly approach. In an effort to protect the environment, the recycling industry is matching pace by implementing new technologies to pursue advanced recycling. These solutions provide feasible and sustainable opportunities to create useful and profitable products while improving circularity.
The following advanced recycling technologies are nearing commercialization and deployment. Proper technology selection depends on several factors:
Pyrolysis
Thermal, also known as non-catalytic, pyrolysis is a common technique used to convert mixed plastic waste (MPW) into fuels or chemical feedstocks. Pyrolysis thermally degrades plastic waste at high temperatures — at approximately 300-900°C — in the absence of oxygen, to produce liquid oil, char and vent gas.
The pyrolysis process starts at MPW collection sites, with these sites also typically completing the pre-treatment needed to separate plastic waste from municipal solid waste (MSW) and/or industrial solid waste. Pre-treatment also includes sorting through waste using manual and mechanical methods to remove paper, metal, food and glass. A benefit of pyrolysis is not having to sort MPW into individual polymers, which is labor intensive, time consuming and inefficient with current practices in place.
Gasification
Gasification involves reacting a gasifying agent, such as oxygen or water, with plastic waste at a high temperature — at approximately 500-1,300°C — to produce syngas. Syngas can be used directly as a fuel or to produce hydrogen, methanol and other chemical/fuel intermediates. The process of gasification involves both the decomposition of plastic waste and the reaction of plastic waste with the gasifying agent.
A variety of waste can be used in a gasification conversion such as MSW, plastics and agricultural waste, thus offering greater flexibility and reduced sorting requirements. This option is most attractive for plants with an existing gasifier that might consider co-feeding MPW with existing feedstock.
Depolymerization
Depolymerization is a collective term for a family of processes in which selected plastics — such as polyethylene terephthalate (PET) from drinking bottles — are processed. The individual plastics are chemically treated to break the polymer linkages, returning to the base monomer.
A major benefit of depolymerization is that it can produce monomers suitable for feed to be used in existing polymerization processes. This is markedly different from other processes, which destroy monomers and produce either fuel or syngas. However, use of depolymerization requires a rigorous MPW sorting process to minimize contamination of the plastic feeding the depolymerization process.
Selection of the appropriate recycling technology depends on the available feedstock, desired product and the MPW feedstock sorting requirements. A rigorous sorting process, coupled with depolymerization, allows for production of high-quality monomers. Whereas a more lenient feedstock specification, coupled with pyrolysis or gasification, generates fuels or syngas.
All of these technologies have been demonstrated at a reasonable scale by multiple technology providers and are nearing large-scale deployment. Implementation of advanced recycling technologies for MPW is expected to experience significant growth in the near term.
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