Globally, there is rising awareness of the severity of the plastic waste problem, and the implications of plastics accumulation in the environment. Current methods of waste management are anticipated ...to be insufficient in mitigating the long-term negative impact on society and the environment. Plastics recycling is one of many solutions that have been proposed, one of the most ecologically-friendly, as well as holding great economic potential by its realization into a circular economy. The technological know-how already exists for a number of different methods for plastic recycling; however, they are broadly uneven in their implementation due to feasibility and cost issues. Here, we review and compare methods of tertiary recycling—that is, complete breakdown of plastics into its chemical component materials—and offer an analysis of the potential obstacles that have to be addressed to increase waste plastic recycling rates. While chemical recycling methods are simpler and are already pilot tested at an industrial level, biological recycling either via microorganisms or biological-derived enzymes are as yet unproven but highly promising technologies. Looking forward, trend shifts towards more ecologically-friendly processes will drive initiatives to close the loop on commercial plastic production.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Proposed a dual-recycling mode for a two-echelon reverse supply chain.•Investigated collecting competition between the recyclable dealer and recycler considering consumer behavior.•Incorporated the ...consumer preference into the customer collection channel choice model.•Examined the optimal recycling channel configuration of the recyclable dealer.
In this paper, we consider a two-echelon reverse supply chain with dual-recycling channels where the recyclable dealer acts as a Stackelberg game leader and the recycler acts as a follower. Due to the price competition between these two channels, the dominant dealer always faces a challenge on how to strategically design the reverse channel structure. By introducing consumer preference for the online recycling channel into the model, we examine the challenge in three scenarios: single traditional recycling channel, single online-recycling channel, and a hybrid dual-recycling channel with both centralized and decentralized cases. We investigate two problems that are comprised of designing and coordinating a reverse supply chain with a traditional and an online recycling channel. The results show that the dual-recycling channel always outperforms its single channel counterparts from the recyclable dealer's and system's perspectives. In the coordination problem, a contract with transfer and online recycling prices can coordinate the dual-recycling channel reverse supply chain but harms the dealer. Therefore, we propose two complementary contracts – a two-part tariff contract and a profit sharing contract – which succeed in coordinating the reverse supply chain system and create a win-win situation. Finally, numerical examples illustrate the model, and results show that the consumer preference for online recycling affects the acceptance of the above contracts for the recyclable dealer.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
This review focuses on the characteristics of the most widely used biopolymers that contain starch, polylactic acid, cellulose and/or polybutylene succinate. Because worldwide production of bio-based ...materials has grown dynamically, their waste is increasingly found in the existing waste treatment plants. The development of recycling methods for bio-based materials remains a challenge in the implementation of a circular economy. This article summarizes the recycling methods for bio-based materials, which, in the hierarchy of waste management, is much more desirable than landfilling. Several methods of recycling are available for the end-of-life management of bio-based products, which include mechanical (reuse of waste as a valuable raw material for further processing), chemical (feedstock recycling) and organic (anaerobic digestion or composting) ones. The use of chemical or mechanical recycling is less favourable, more costly and requires the improvement of systems for separation of bio-based materials from the rest of the waste stream. Organic recycling can be a sustainable alternative to those two methods. In organic recycling, bio-based materials can be biologically treated under aerobic or anaerobic conditions, depending on the characteristics of the materials. The choice of the recycling method to be implemented depends on the economic situation and on the properties of the bio-based products and their susceptibility to degradation. Thus, it is necessary to label the products to indicate which method of recycling is most appropriate.
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NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
In a sustainable circular economy, polymers capable of chemical recycling to monomers are highly desirable. We report an efficient monomer‐polymer recycling of polydithioacetal (PDTA). Pristine PDTAs ...were readily synthesized from 3,4,5‐trimethoxybenzaldehyde and alkyl dithiols. They then exhibited depolymerizability via ring‐closing depolymerization into macrocycles, followed by entropy‐driven ring‐opening polymerization (ED‐ROP) to reform the virgin polymers. High conversions were obtained for both the forward and reverse reactions. Once crosslinked, the network exhibited thermal reprocessability enabled by acid‐catalyzed dithioacetal exchange. The network retained the recyclability into macrocyclic monomers in solvent which can repolymerize to regenerate the crosslinked network. These results demonstrated PDTA as a new molecular platform for the design of recyclable polymers and the advantages of ED‐ROP for which polymerization is favored at higher temperatures.
Polydithioacetals depolymerize to a mixture of macrocycles that regenerates the parent polymers via entropy‐driven ring‐opening polymerization. When crosslinked, they demonstrate covalent adaptable network (CAN) behavior at elevated temperatures. The swollen CANs are also depolymerizable to macrocycles, which are polymerized back to the CANs. Polydithioacetals are thus desirable candidates as chemically recyclable thermoplastics and thermosets.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This study assesses the environmental impact of polyethylene terephthalate (PET) bottle-to-fibre recycling using the methodology of life-cycle assessment (LCA). Four recycling cases, including ...mechanical recycling, semi-mechanical recycling, back-to-oligomer recycling and back-to-monomer recycling were analysed. Three allocation methods are applied for open-loop recycling, i.e. the “cut-off” approach, the “waste valuation” approach and the “system expansion” approach. Nine environmental impact indicators were analysed, i.e. non-renewable energy use (NREU), global warming potential (GWP), abiotic depletion, acidification, eutrophication, human toxicity, fresh water aquatic ecotoxicity, terrestrial ecotoxicity and photochemical oxidant formation. The LCA results are compared with virgin PET fibre and other commodity fibre products, i.e. cotton, viscose, PP (polypropylene) and PLA (polylactic acid). The LCA results show that recycled PET fibres offer important environmental benefits over virgin PET fibre. Depending on the allocation methods applied for open-loop-recycling, NREU savings of 40–85% and GWP savings of 25–75% can be achieved. Recycled PET fibres produced by mechanical recycling cause lower environmental impacts than virgin PET in at least eight out of a total of nine categories. Recycled fibres produced from chemical recycling allow to reduce impacts in six to seven out of a total of nine categories compared to virgin PET fibres. Note that while mechanical recycling has a better environmental profile than chemical recycling, chemically recycled fibres can be applied in a wider range of applications than mechanically recycled fibres.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Asia currently faces a serious crisis involving plastic wastes. Efforts to curb plastic waste in the region are mostly hampered by inadequate recycling infrastructure, unsustainable disposal ...practice, low level of recycling awareness and persistent shipping of large amounts of waste from developed countries to the region. The ban on plastic waste import by China in 2017 worsened the situation by causing unsustainable shipping of waste from high plastic waste-generating countries such as Japan to alternate destinations in Southeast and East Asia. The Japanese government is frantically looking for options to manage plastic waste piling up on the domestic front. Malaysia became one of the leading alternative destinations for plastic waste after the ban by China. This work is aimed at conducting a comparative analysis of plastic recycling policies and legislations between Malaysia and Japan to yield synergistic solutions between the two countries to combat the current predicament. The comparison will signify two typical development patterns in developed countries and developing countries and will be able elucidate future directions for other countries with similar policy and legislative transitions in the region. A set of nine criteria was employed to critically evaluate the policies and legislations of both countries. Barriers faced by both countries in plastic recycling are outlined and recommendations are proposed to overcome those barriers on the domestic front. Two strategies proposed to be jointly developed by both countries are enhancement of extended producer responsibility (EPR) through a regional policy platform and collaboration in establishing joint Ecotowns.
Graphical abstract
The circular economy Stahel, Walter R
Nature,
03/2016, Volume:
531, Issue:
7595
Journal Article
Peer reviewed
Open access
A new relationship with our goods and materials would save resources and energy and create local jobs, explains Walter R. Stahel.
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IJS, KISLJ, NUK, SBMB, UL, UM, UPUK
48.
Recycling of Bioplastics: Routes and Benefits Lamberti, Fabio M.; Román-Ramírez, Luis A.; Wood, Joseph
Journal of polymers and the environment,
10/2020, Volume:
28, Issue:
10
Journal Article
Peer reviewed
Open access
Continual reduction of landfill space along with rising CO
2
levels and environmental pollution, are global issues that will only grow with time if not correctly addressed. The lack of proper waste ...management infrastructure means gloablly commodity plastics are disposed of incorrectly, leading to both an economical loss and environmental destruction. The bioaccumulation of plastics and microplastics can already be seen in marine ecosystems causing a negative impact on all organisms that live there, ultimately microplastics will bioaccumulate in humans. The opportunity exists to replace the majority of petroleum derived plastics with bioplastics (bio-based, biodegradable or both). This, in conjunction with mechanical and chemical recycling is a renewable and sustainable solution that would help mitigate climate change. This review covers the most promising biopolymers PLA, PGA, PHA and bio-versions of conventional petro-plastics bio-PET, bio-PE. The most optimal recycling routes after reuse and mechanical recycling are: alcoholysis, biodegradation, biological recycling, glycolysis and pyrolysis respectively.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Over the past 30 years, China has been suffering from negative environmental impacts from distempered waste electrical and electronic equipments (WEEE) recycling activities. For the purpose of ...environmental protection and resource reusing, China made a great effort to improve WEEE recycling. This article reviews progresses of three major fields in the development of China’s WEEE recycling industry: legal system, formal recycling system, and advanced integrated process. Related laws concerning electronic waste (e-waste) management and renewable resource recycling are analyzed from aspects of improvements and loopholes. The outcomes and challenges for existing formal recycling systems are also discussed. The advantage and deficiency related to advanced integrated recycling processes for typical e-wastes are evaluated respectively. Finally, in order to achieve high disposal rates of WEEE, high-quantify separation of different materials in WEEE and high added value final products produced by separated materials from WEEE, an idea of integrated WEEE recycling system is proposed to point future development of WEEE recycling industry.
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IJS, KILJ, NUK, PNG, UL, UM
Increased media coverage of plastic pollution in the environment and import bans on plastic waste in several countries have resulted in plastic waste becoming one of the most discussed waste streams ...in recent years. In the European Union (EU), only about one-third of the post-consumer plastic waste is recycled; the rest goes to energy recovery and landfilling in equal parts. In connection to the necessary increase in efforts to achieve the ambitious EU recycling targets, chemical recycling is currently receiving more and more attention. The assumption is that chemical recycling processes could open up new waste streams for recycling and generate valuable raw materials for the chemical industry. Although there exists no legal definition for chemical recycling, there is more or less agreement that it covers the conversion of plastic polymers into their monomers or chemical building blocks. Techniques such as gasification, pyrolysis and liquefaction as well as solvolysis can be used for chemical recycling. So far, only few large-scale plants for chemical recycling exist worldwide. This article presents the different processes by means of examples from (formerly) running installations and their suitability for plastics recycling is assessed. However, to date, only few chemical recycling plants are in continuous operation, and further scientific evidence for the ecological and economic benefits is still necessary for final evaluation.
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