Plastic Recycling Technology Research Articles

Screening of polyurethane-degrading microbes using a quenching fluorescence probe by microfluidic droplet sorting

Excessive use of polyurethane (PU) polymers has led contributed to serious environmental pollution. The plastic recycling technology using microorganisms and enzymes as catalysts offers a promising green and low-carbon approach for managing plastic waste. However, current methods for screening PU-degrading strains suffer from drawbacks such as being time-consuming and inefficient. Herein, we present a novel approach for screening PU-degrading microorganisms using a quenching fluorescent probe along with the fluorescence-activated droplet sorting (FADS). The FPAP could specifically recognize the 4,4′-methylenedianiline (MDA) derivates released from PU degradation, with fluorescence quenching as a response. Based on the approach, we successfully screen two PU-degrading strains (Burkholderia sp. W38 and Bacillus sp. C1). After 20 d of cultivation, strain W38 and C1 could degrade 41.58% and 31.45% of polyester-PU film, respectively. Additionally, three metabolites were identified during the degradation of PU monomer (2,4-toluene diamine, 2,4-TDA) and a proposed degradation pathway was established. Consequently, the fluorescence probe integrated with microfluidic droplet systems, demonstrates potential for the development of innovative PU-biocatalysts. Furthermore, the identification of the 2,4-TDA degradation pathway provides valuable insights that can propel advancements in the field of PU biodegradation.

Electrocatalytic upcycling of plastic waste: Progress, challenges, and future

AbstractThe escalating accumulation of plastic waste has been developed into a formidable global environmental challenge. Traditional disposal methods such as landfilling and incineration not only exacerbate environmental degradation by releasing harmful chemicals and greenhouse gases, but also squander finite resources that could otherwise be recycled or repurposed. Upcycling is a kind of plastic recycling technology that converts plastic waste into high‐value chemicals and helps to avoid resource waste and environmental pollution. Electrocatalytic upcycling emerges as a novel technology distinguished by its mild operational conditions, high transformation efficiency and product selectivity. This review commences with an overview of the recycling and upcycling technology employed in plastic waste management and the respective advantages and inherent limitations are also delineated. The different types of plastic waste upcycled by electrocatalytic strategy are then discussed and the plastic waste transformation process is examined together with the mechanisms underlying the electrocatalytic upcycling. Furthermore, the structure‐activity relationships between electrocatalysts and plastic waste upcycling performance are also elucidated. The review aims to furnish readers with a comprehensive understanding of the electrocatalytic techniques for plastic waste upcycling and to provide a guidance for the design of electrocatalysts towards efficient plastic waste transformation.

Technology evolution in heterogeneous technological fields: A main path analysis of plastic recycling

Driven by the ubiquity of plastic waste and its danger to environment and health, there have been increased efforts in the development of plastic recycling technologies. However, plastic recycling is a heterogeneous technological field which involves different application contexts, process stages, and technological approaches. In this paper, we study the structure of interrelated technological development of different recycling technologies. Utilizing patent citation data on more than 100,000 patents and focusing on textile applications, separation techniques, and biological recycling as example subdomains, we use patent-based main path analysis to delineate the co-evolution of technological trajectories. We report two main findings: First, comparative analysis of the three domains shows that differences in main path cohesion and homogeneity coincide with differences in development maturity and organizational concentration of patenting activity. Second, integrated analysis of the three domains shows a strong degree of historical dependence between textile recycling and separation techniques while biological recycling has so far mostly developed in its own niche.

Development of an economically viable plastic recovery waste management system in Cibodas and Padamukti Village, West Java

Out of the 2,142 existing community-managed sorting and recycling facilities in Indonesia, known as TPS-3R, only 14% are functioning optimally due to economic challenges, highlighting the need for financially viable TPS-3R. To address this issue, the research aims to recommend an economically viable plastic recovery waste management system with optimum residue and income. Cibodas and Padamukti Villages are chosen as the case study location, as it has only 20% waste collection coverage and is located in the Citarum Watershed, whose river is a source of water for 60 million people and is part of the Citarik Ecotourism Living Lab. Primary data collection was carried out through interviews with recyclers in the villages and through waste volume and composition characterization. Three scenarios were developed for the Plastic Recovery Facility (PRF) objectives: Scenario 1 (S1) serves as the baseline of PRF, Scenario 2 (S2) buys plastic wastes from existing traders to be processed with more advanced plastic recycling technologies, and Scenario 3 (S3) is a self-sustaining PRF that could be replicated for the whole villages. Data analysis involved mass balance, financial models, BCR, NPV, and multicriteria decision-making. The residue disposed of in landfills is 32%, 17%, and 28% of the total waste managed for S1, S2, and S3. Financial modeling yielded BCR values of 1.06, 1.15, and 1.24, as well as NPV +IDR78,036,332; +IDR465,224,754; and +IDR354,414,072. The results highlight the importance of detailed analysis of mass balance and financial modeling according to the waste composition in any TPS-3R location, especially the differences in the value of rigid and flexible plastics, which will affect the types of technology and products. While the recommended scenario, S3, does not eliminate the need for capital investment from the government, it provides a framework to plan PRF with an operating surplus, which will increase the community’s willingness to run it and ensure the PRF’s long-term functionality to yield social and environmental benefits.

Determination of circular economy targets based on absolute sustainability: A case study on plastics

Plastic production significantly contributes to greenhouse gas emissions, making up around 4.5% of total emissions. As plastic consumption is expected to rise, it’s crucial to address the environmental impact of this industry urgently. Circular economy strategies, like recycling, are proposed solutions to reduce plastic’s carbon footprint. However, these strategies lack specific carbon footprint targets for plastics used in various applications. This study focuses on plastics in the automotive industry, establishing specific carbon footprint goals for plastics used in passenger cars. It also examines mechanical recycling’s role and the share of secondary plastics in meeting these absolute targets. The analysis of mechanical recycling technology reveals that even with 100% recycled plastics, the carbon footprint targets aren’t achieved due to high process energy consumption. Investigating grid emission factors, results show that meeting targets requires emission factors lower than 0.13 kgCO2-eq./kWh. Despite successful scenarios, it’s presently infeasible to use 100% recycled plastics in passenger car production. This necessitates the need to further improve plastic recycling technologies and increase the share of secondary plastics used in passenger car production.

Co-production of hydrogen and carbon nanotubes via catalytic pyrolysis of polyethylene over Fe/ZSM-5 catalysts: Effect of Fe loading on the catalytic activity

Thermochemical conversion is a promising waste plastic recycling technology from both an economic and environmental point of view, as it can convert plastics into high-value chemicals. In this work, the co-production of hydrogen and carbon nanotubes (CNTs) by catalytic pyrolysis of polyethylene over Fe/ZSM-5 catalysts with different Fe loading (5, 10, 20 and 30 wt%) was investigated using a two-stage fixed bed reactor. The results show that the yield of CNTs and hydrogen increases first and then decreases with the increase of Fe loading. The 20Fe/ZSM-5 catalyst generated the highest CNTs yield of 262.24 mg/gPE and the maximum hydrogen production of 31.72 mmol/gPE. The fresh and spent catalysts were characterized by XRD, H2-TPR, SEM, TEM, etc., in order to explore the correlation between the catalytic activity and the Fe active metal load of the catalysts. The results showed that, within a certain range, the number of active sites increased with the increase of Fe loading, which promoted the conversion of hydrogen and CNTs. However, when the Fe loading reached 30%, the active particles agglomerated and inhibited the growth of CNTs. 30Fe/ZSM-5 catalyst produced many carbon nanoonions (CNOs) and carbon nanofibers (CNFs). Overall, in terms of the yield of the produced hydrogen and CNTs, the 20Fe/ZSM-5 catalyst shows the best catalytic performance.

A recycling technology selection framework for evaluating the effectiveness of plastic recycling technologies for circular economy advancement

Despite progress in plastic waste recycling technologies, global plastic waste recycling rates remain disappointing. This problem not only suggests an underutilization of existing recycling technologies but also hinders resource utilization, the circular economy, and sustainable manufacturing. Several studies have proposed addressing this issue by evaluating recycling technologies based on recycled waste volume. However, such single-indicator methods often overlook other critical factors and, thus, may not provide holistic assessments. Additionally, existing methods for evaluating or comparing different recycling technologies are often complex and time-consuming. In contrast, other studies have proposed hundreds of indicators for assessing the effectiveness and suitability of recycling technologies, further complicating the selection process. Consequently, recyclers and other stakeholders often struggle to identify the most effective and suitable recycling technologies for different plastic waste types and under specific conditions. To address these challenges, we propose the recycling technology selection framework (RTSF), a simple tool that enables easy visualization of relevant recycling indicators under five key pillars: economic, technical, environmental, social, and policy. By enabling recyclers and stakeholders to quickly identify, select, and visualize factors of interest from a large pool, the RTSF facilitates qualitative comparison and enhances the evaluation of the effectiveness and suitability of multiple plastic recycling technologies. Lastly, the RTSF can serve as a preliminary tool and be integrated with other approaches to enhance the effectiveness of plastic recycling technologies.

Comparative Analysis of Environmental, Economic, and Social Criteria for Plastic Recycling Technology Selection in India, Sri Lanka, Pakistan, and Thailand

Comparative Analysis of Environmental, Economic, and Social Criteria for Plastic Recycling Technology Selection in India, Sri Lanka, Pakistan, and Thailand

Harnessing extremophilic carboxylesterases for applications in polyester depolymerisation and plastic waste recycling.

The steady growth in industrial production of synthetic plastics and their limited recycling have resulted in severe environmental pollution and contribute to global warming and oil depletion. Currently, there is an urgent need to develop efficient plastic recycling technologies to prevent further environmental pollution and recover chemical feedstocks for polymer re-synthesis and upcycling in a circular economy. Enzymatic depolymerization of synthetic polyesters by microbial carboxylesterases provides an attractive addition to existing mechanical and chemical recycling technologies due to enzyme specificity, low energy consumption, and mild reaction conditions. Carboxylesterases constitute a diverse group of serine-dependent hydrolases catalysing the cleavage and formation of ester bonds. However, the stability and hydrolytic activity of identified natural esterases towards synthetic polyesters are usually insufficient for applications in industrial polyester recycling. This necessitates further efforts on the discovery of robust enzymes, as well as protein engineering of natural enzymes for enhanced activity and stability. In this essay, we discuss the current knowledge of microbial carboxylesterases that degrade polyesters (polyesterases) with focus on polyethylene terephthalate (PET), which is one of the five major synthetic polymers. Then, we briefly review the recent progress in the discovery and protein engineering of microbial polyesterases, as well as developing enzyme cocktails and secreted protein expression for applications in the depolymerisation of polyester blends and mixed plastics. Future research aimed at the discovery of novel polyesterases from extreme environments and protein engineering for improved performance will aid developing efficient polyester recycling technologies for the circular plastics economy.

Rapid and accurate quality assessment method of recycled food plastics VOCs by electronic nose based on Al-doped zinc oxide

Plastic recycling technologies are being actively developed and implemented to cope with increasing volume of plastic. Such technologies require new analytical tools able to control the quality of the recycled polymers to be further integrated in production processes. Here, we propose a rapid and selective quality assessment method for polymer materials made of high-density polyethylene using electronic nose with aluminum doped zinc oxide sensing material in combination with the RandomForestClassifier machine learning tool. We test total content of volatile organic compounds both odor-active responsible for the smell and odorless of primary and secondary plastics, and evaluate corresponding organic vapors emitted by the plastics by headspace gas chromatography and mass-spectrometry at optimized conditions like sample temperature, sensor signal recovery time. The electronic nose demonstrated the good correlation of vector signal with the emitted volatile compounds with an accuracy more than 98.5% when discriminating between primary and secondary plastics. Addition of zeolites to the recycled plastic is shown to decrease the appearance of off-odors.

Towards Plastic Circularity: Current Practices in Plastic Waste Management in Japan and Sri Lanka

Despite their different economic backgrounds, Japan and Sri Lanka share similarities as island nations. As a developing country, Sri Lanka needs to identify the country’s existing situation of Plastic Waste Management (PWM) to improve the circularity in the sector. Japan’s existing PWM strategies are a pointer for Sri Lanka to improve the circularity along the plastic value chain. The main aspects that are considered in this study are quantitative data related to the plastic value chain, plastic recycling technologies, plastic recycling businesses, policies, regulations related to plastic waste management, and public awareness strategies in plastic waste management. The methodology relied on literature review and interviews. The main focus of these interviews was to fill the information gap that was identified during the literature review. Japan is practicing all the stages of the plastic value chain, including virgin plastic production, whereas virgin plastic production is absent in Sri Lanka. Technological and policy advancements like the application of Extended Producer Responsibility (EPR) in PWM in Japan can be used as a means of achieving circularity in the Sri Lankan PWM sector. The well-established informal plastic recycling industry in Sri Lanka is a significant feature compared to Japan’s formal plastic recycling industry.

Photocatalysis as an Effective Tool for Upcycling Polymers into Value-Added Molecules.

Shaping a sustainable future is closely tied to the development of advanced plastic recycling technologies. As global recycling rates remain low, the lion's share of post-consumer plastics is either incinerated or disposed of in landfills. This unbalanced plastic waste management not only poses severe environmental risks, but also entails an irrevocable loss of chemical resources that are embedded in synthetic polymers. To give plastic waste a new life, a series of photocatalytic methods has recently been reported that convert polymers directly into value-added organic molecules. These approaches operate at ambient temperature, show high reactivity/selectivity, and provide alternative reaction pathways as compared to thermal depolymerizations. This Minireview highlights the scientific breakthroughs in upcycling polymers through state-of-the-art photocatalysis under environmentally benign conditions.

Photocatalysis as an Effective Tool for Upcycling Polymers into Value‐Added Molecules

AbstractShaping a sustainable future is closely tied to the development of advanced plastic recycling technologies. As global recycling rates remain low, the lion's share of post‐consumer plastics is either incinerated or disposed of in landfills. This unbalanced plastic waste management not only poses severe environmental risks, but also entails an irrevocable loss of chemical resources that are embedded in synthetic polymers. To give plastic waste a new life, a series of photocatalytic methods has recently been reported that convert polymers directly into value‐added organic molecules. These approaches operate at ambient temperature, show high reactivity/selectivity, and provide alternative reaction pathways as compared to thermal depolymerizations. This Minireview highlights the scientific breakthroughs in upcycling polymers through state‐of‐the‐art photocatalysis under environmentally benign conditions.

Life Cycle Cost and Assessment of Alternative Railway Sleeper Materials

Improvements in plastic recycling technology along with pressure to reduce emissions and waste has led to a desire to find environmentally friendly, cost competitive railway sleepers. This study conducts life cycle analyses of emissions and costs for timber, concrete, short fibre and long fibre composite railway sleepers to determine which sleepers are more environmentally friendly and cost competitive. The results clearly highlight the environmental advantages of short fibre plastic composites. The basic scenario had concrete sleepers being the most cost competitive, before factoring in the recyclability and likely future cost reductions of short fibre composite sleepers. With as little as 50% of the entirely recyclable short fibre sleepers being recycled their cost quickly becomes comparable to concrete sleepers. Further, there are several likely changes in the future that will make short fibre sleepers even more cost competitive. The short fibre industry is still growing and could substantially reduce costs through the effects of economies of scale and experience curves of production. A further driver of future cost competitiveness would be the broader use of an Australian or international carbon price, where concrete sleepers have a disadvantage. Together, these changes indicate that short fibre composites have great potential financially and environmentally.

The impact of secondary materials’ quality on assessing plastic recycling technologies

Global plastic production reached a new high in 2019. The high use of plastic leads to a high amount of plastic waste. Thereof, only 33% was collected for recycling in Europe. Plastic production depends on crude oil and energy and has high environmental impacts such as greenhouse gas emissions. The recycling of plastic waste can reduce dependency on fossil resources, help reduce environmental impacts, and achieve sustainability goals. Currently, the chemical recycling of plastic is discussed to complement the existing mechanical recycling. Comparing the recycling technologies is needed to identify and establish the most environmentally and economically promising technology for each waste stream. However, the quality of the recovered material has a high impact on assessment results. This study discusses different assessment metrics for recycling technologies concerning the influence of recovered materials’ quality by material substitution rates and circularity potential. In a case study, mechanical and chemical recycling via pyrolysis of HDPE from lightweight packaging waste from Germany is assessed. Mechanical recycling has a lower climate change impact than chemical recycling for material substitution rates above 0.85. On the other hand, chemical recycling has a higher potential to close the plastic loop and retain plastics within the economy due to the higher secondary material quality. The assessment allows evaluating recycling options for the considered plastics from the German collection systems for packaging.

Chemical Feedstock Recovery from Hard-to-Recycle Plastics through Pyrolysis-Based Approaches and Pyrolysis-Gas Chromatography

Abstract The entire world is moving toward carbon neutrality, and Japan is aiming to achieve a carbon neutral society by 2050. Generation of waste plastic is annually increasing, and the demand for waste plastic recycling is rapidly and globally growing to allow sustainable plastic use. Therefore, rapid and substantial promotion of plastic recycling technology is a global preferential task. The authors believe that pyrolysis is a promising strategy for recovering chemical feedstock from waste plastics, which improves global recycling capacity. Herein, global trends in waste plastic recycling were summarized in the first chapter, and feedstock recycling through pyrolysis-based approaches for hard-to-recycle plastic wastes such as polyethylene terephthalate (PET) and polyurethanes (PUs) were reviewed in the second chapter. Finally, the applicability of pyrolysis-gas chromatography (Py-GC) was verified by the investigation of the pyrolysis reaction mechanism, in situ pyrolyzate monitoring, and rapid screening of pyrolysis and catalytic reaction conditions.

Open Source Filament Diameter Sensor for Recycling, Winding, and Additive Manufacturing Machines

Abstract To overcome the challenge of upcycling plastic waste into three-dimensional (3D) printing filament in the distributed recycling and additive manufacturing systems, this study designs, builds, tests, and validates an open-source filament diameter sensor for recycling and winding machines. The modular system for multi-axis optical control of the diameter of the recycled 3D-printer filament makes it possible to scan part of the surface of the processed filament, save the history of measurements along the entire length of the spool, as well as mark defective areas. The sensor is developed as an independent module and integrated into a recyclebot. It was tested on different kinds of polymers (acrylonitrile butadiene styrene (ABS), polylactide (PLA)), different sources of plastic, and different colors including clear plastic. The results were compared with the manual measurements, and the measurements obtained with a one-dimensional digital light caliper. The results found that the developed open-source filament sensing method allows users to obtain significantly more information in comparison with basic one-dimensional light sensors and using the received data not only for more accurate diameter measurements but also for a detailed analysis of the recycled filament surface. This could help to expand the use of plastic recycling technologies in the manufacturing community. The availability of tools for possible texture analysis could also stimulate the growth of composite materials creation. The presented system can greatly enhance the user possibilities and serve as a starting point for a complete recycling control system that will regulate motor parameters to achieve the desired filament diameter with acceptable deviations and even control the extrusion rate on a printer to recover from filament irregularities.

Anellotech receives funds to develop plastic recycling technology

Anellotech receives funds to develop plastic recycling technology

Life cycle energy comparison of different polymer recycling processes

AbstractThis article is to demonstrate a consistent, transparent approach to comparing plastic recycling technologies. The uniform comparison is based on each recycling technology having the same input (waste PET), mass basis for processing, output as new product (new PET product or fuels), and the concept of the same multiple (two) closed loops of recycling. We seek to demonstrate, at the fundamental technology level, how energy use differentiates plastic recycling technologies. Five polymer‐recycling processes are examined using a uniform, quantitative comparison of 1 kg PET bottles (about 100 single‐serve 0.5 L water bottles): direct reuse, 100% mechanical recycled content, depolymerization, and re‐polymerization of new resin and 100% to bottles, reclaiming energy value, and landfill. The life cycle energy benefit for recycle technologies with varying product recycled content can be determined by a single equation. All these recycling processes resulted in total energy reduction per kg PET bottles compared to landfilling. The base case of three cycles per 1 kg PET bottles is used to explore the influence of recycling loops. Direct reuse gave a 290% energy improvement with three cycles. Other processes, all at 100% recycle content, gave improvements: mechanical (250%), depolymerization/repolymerization (150%), and energy recovery (120%). More information would improve the analysis of the depolymerization process assessment. These preliminary data describe the analyses that are needed to quantify the benefit of recycling any polymer using these recycling methods. The Environmental Genome (“EGI”) provides valuable information for these calculations as it contains the polymers and supply chains for such evaluations.

Crisis of Plastic Waste in Vietnam is Real

The issue of "white pollution" at popular tourist destinations of environmental pollution is rising at an alarming rate. According to statistics, Vietnam currently ranks fourth in the world in volume of plastic waste, with approximately 730,000 tons of plastic waste going to the sea every year. Vietnam is also known as a country with twice the amount of plastic waste compared to low-income countries. Plastic waste in the ocean will destroy the natural environment, negatively affecting the lives of aquatic products. On land, plastic waste is abundant in many places and has serious impacts on human health and life. Analysts point out that, if the pace of use of plastic products continues to increase, there will be an additional 33 billion tons of plastic produced by 2050 and thus more than 13 billion tons of plastic waste will be buried. backfill into landfills or into the ocean. Meanwhile, the recycling of Vietnam's plastic waste, has not been developed. The rate of waste sorting at the source is very low, most types of waste are put together and collected by waste trucks. Plastic recycling technology used in Vietnam's major cities is outdated, low in efficiency, high in costs and polluting the environment. The paper presents the current situation of plastic waste in Vietnam as of June 2019. The authors focus on highlighting the serious "white pollution" in Vietnam, a country with a very long coastline. But the coast is really threatened by plastic waste. This is really a wake-up call to the authorities about the promulgation of policies and the people on the morality of survival with nature.