Plastic waste in a circular economy

Hahladakis, John Ν.; Iacovidou, Eleni; Gerassimidou, Spyridoula

doi:10.1016/b978-0-12-817880-5.00019-0

Cited by 62 publications

(55 citation statements)

References 69 publications

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“…Fatty‐acid based plastic lubricants, often used to facilitate the easy opening of plastic bags in shops, can be oxidized to produce unwanted odors in the recyclate. [ 54,55,56 ] Extraneous plastics from incorrect sorting can exacerbate these issues or even lead to process failure. Trace amounts of PVC in PET streams induces hydrodechlorination at PET processing temperatures.…”

Section: Plastic Waste Recyclingmentioning

confidence: 99%

“…The resultant release of HCl in turn accelerates PET degradation ( Figure ) and damages processing equipment. [ 57,55 ] The presence of polyamides can also catalyze the aminolysis of PET which increases chain scission. [ 27 ] If a polymer blends is produced, due to accidental processing of mixed polymer waste streams, both the food‐grade safety standards and mechanical properties are compromised., such as polyolefin and PET blends.…”

Section: Plastic Waste Recyclingmentioning

confidence: 99%

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Mechanical Recycling of Packaging Plastics: A Review

Schyns

Shaver

2020

Macromol. Rapid Commun.

787

692

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The current global plastics economy is highly linear, with the exceptional performance and low carbon footprint of polymeric materials at odds with dramatic increases in plastic waste. Transitioning to a circular economy that retains plastic in its highest value condition is essential to reduce environmental impacts, promoting reduction, reuse, and recycling. Mechanical recycling is an essential tool in an environmentally and economically sustainable economy of plastics, but current mechanical recycling processes are limited by cost, degradation of mechanical properties, and inconsistent quality products. This review covers the current methods and challenges for the mechanical recycling of the five main packaging plastics: poly(ethylene terephthalate), polyethylene, polypropylene, polystyrene, and poly(vinyl chloride) through the lens of a circular economy. Their reprocessing induced degradation mechanisms are introduced and strategies to improve their recycling are discussed. Additionally, this review briefly examines approaches to improve polymer blending in mixed plastic waste streams and applications of lower quality recyclate.

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Section: Plastic Waste Recyclingmentioning

confidence: 99%

Section: Plastic Waste Recyclingmentioning

confidence: 99%

Mechanical Recycling of Packaging Plastics: A Review

Schyns

Shaver

2020

Macromol. Rapid Commun.

787

692

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“…Plastic production is relatively sustainable when compared with the resource-intensive processes associated with other materials such as glass and metal. That said, there is a huge need to re-evaluate plastic design, production, use and management in order to improve its ability to re-enter the system and to ensure that maximum value is being recovered ( Hahladakis et al, 2020 ). Through a combination of biodegradation and biosynthesis, there is potential for a circular, bio-based PET economy that could play a significant role in reducing the associated detrimental environmental effects.…”

Section: Future Perspectivesmentioning

confidence: 99%

Microbial Polyethylene Terephthalate Hydrolases: Current and Future Perspectives

2020

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Plastic has rapidly transformed our world, with many aspects of human life now relying on a variety of plastic materials. Biological plastic degradation, which employs microorganisms and their degradative enzymes, has emerged as one way to address the unforeseen consequences of the waste streams that have resulted from mass plastic production. The focus of this review is microbial hydrolase enzymes which have been found to act on polyethylene terephthalate (PET) plastic. The best characterized examples are discussed together with the use of genomic and protein engineering technologies to obtain PET hydrolase enzymes for different applications. In addition, the obstacles which are currently limiting the development of efficient PET bioprocessing are presented. By continuing to study the possible mechanisms and the structural elements of key enzymes involved in microbial PET hydrolysis, and by assessing the ability of PET hydrolase enzymes to work under practical conditions, this research will help inform large-scale waste management operations. Finally, the contribution of microbial PET hydrolases in creating a potential circular PET economy will be explored. This review combines the current knowledge on enzymatic PET processing with proposed strategies for optimization and use, to help clarify the next steps in addressing pollution by PET and other plastics.

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“…Microplastic pollution continues to induce negative impacts that harm both animals and ecosystems. Nevertheless, the plastic manufacturing sector has moved to a circular economy that calls for upstream and downstream industry collaborations in chemical and mechanical recycling to create new resins offered with recycled and biobased content ( Hahladakis et al, 2020 ). However, awareness among consumers regarding the efficient postuse of petrochemical plastics, the benefits of green material and government regulations that encourage people to adopt eco-friendly alternatives still promote the demand for bioplastics and biodegradable plastics.…”

Section: Introductionmentioning

confidence: 99%

Polyhydroxybutyrate (PHB) Production Using an Arabinose-Inducible Expression System in Comparison With Cold Shock Inducible Expression System in Escherichia coli

Napathorn

Visetkoop

Pinyakong

et al. 2021

Front. Bioeng. Biotechnol.

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Cupriavidus necator strain A-04 has shown 16S rRNA gene identity to the well-known industrial strain C. necator H16. Nevertheless, the cell characteristics and polyhydroxyalkanoate (PHA) production ability of C. necator strain A-04 were different from those of C. necator H16. This study aimed to express PHA biosynthesis genes of C. necator strain A-04 in Escherichia coli via an arabinose-inducible expression system. In this study, the PHA biosynthesis operon of C. necator strain A-04, consisting of three genes encoding acetyl-CoA acetyltransferase (phaAA–04, 1182 bp, 40.6 kDa), acetoacetyl-CoA reductase (phaBA–04, 741 bp, 26.4 kDa) and PHB synthase Class I (phaCA–04, 1770 bp), was identified. Sequence analysis of the phaAA–04, phaBA–04, and phaCA–04 genes revealed that phaCA–04 was 99% similar to phaCH16 from C. necator H16. The difference in amino acid residue situated at position 122 of phaCA–04 was proline, whereas that of C. necator H16 was leucine. The intact phaCABA–04 operon was cloned into the arabinose-inducible araBAD promoter and transformed into E. coli strains Top 10, JM109 and XL-1 blue. The results showed that optimal conditions obtained from shaken flask experiments yielded 6.1 ± 1.1 g/L cell dry mass (CDM), a PHB content of 93.3 ± 0.9% (w/w) and a productivity of 0.24 g/(L⋅h), whereas the wild-type C. necator strain A-04 accumulated 78% (w/w) PHB with a productivity of 0.09 g/(L⋅h). Finally, for the scaled-up studies, fed-batch cultivations by pH-stat control in a 5-L fermenter of E. coli strains XL1-Blue harboring pBAD/Thio-TOPO-phaCABA–04 and pColdTF-phaCABA–04 in MR or LB medium, leading to a PHB production of 31.4 ± 0.9 g/L at 54 h with a PHB content of 83.0 ± 3.8% (w/w), a CDM of 37.8 ± 1.2 g/L, a YP/S value of 0.39 g PHB/g glucose and a productivity of 0.6 g PHB/(L⋅h) using pColdTF-phaCABA–04 in MR medium. In addition, PHB production was 29.0 ± 1.1 g/L with 60.2 ± 2.3% PHB content in the CDM of 53.1 ± 1.0 g/L, a YP/S value of 0.21 g PHB/g glucose and a productivity of 0.4 g PHB/(L⋅h) using pBAD/Thio-TOPO-phaCABA–04 in LB medium. Thus, a relatively high PHB concentration and productivity were achieved, which demonstrated the possibility of industrial production of PHB.

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Plastic waste in a circular economy

Cited by 62 publications

References 69 publications

Mechanical Recycling of Packaging Plastics: A Review

Mechanical Recycling of Packaging Plastics: A Review

Microbial Polyethylene Terephthalate Hydrolases: Current and Future Perspectives

Polyhydroxybutyrate (PHB) Production Using an Arabinose-Inducible Expression System in Comparison With Cold Shock Inducible Expression System in Escherichia coli

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