Post-consumer Waste Research Articles

Closed loop mechanical recyclability of post-consumer waste wool fabrics based on fibre length retention

Closed loop mechanical recyclability of post-consumer waste wool fabrics based on fibre length retention

Upcycling of waste acrylonitrile butadiene styrene as N-doped carbocatalyst for peroxymonosulfate-induced degradation by solvothermal process

Advanced upcycling of post-consumer waste plastics into functional carbocatalyst has emerged rapidly as a strategy for simultaneously achieving waste plastics disposal and alternative catalysts fabrication. In this study, this type of magnetic N-doped carbocatalyst hybrid was fabricated by a facile solvothermal impregnation of metallic nitrates into waste acrylonitrile butadiene styrene polymer. The key point of the process was that solvothermal impregnation remarkably enhanced a homogeneous metal dispersion and graphitic N structure was stably introduced into carbocatalyst due to N heteroatoms in inherent structure of waste plastics. It was found that carbocatalyst with predominant encapsulation of magnetic CoFe2O4, Fe0.64Ni0.36 and CoFe possessed excellent catalytic performance to activate peroxymonosulfate with substantial degradation of 98.3% synthetic azo contaminant. Mechanism study indicated that graphitic N and metal species exhibited strong synergistic effects for peroxymonosulfate activation to generate SO4·−, ·OH and 1O2. This system achieves a dual-pathway degradation and electron transfer from azo contaminant to peroxymonosulfate to dominate degradation of azo contaminant, providing a new insight into magnetic carbocatalyst confinement from plastic scrap for peroxymonosulfate activation and its versatile application in wastewater reclamation.

Decomposition and fragmentation of conventional and biobased plastic wastes in simulated and real aquatic systems

AbstractPlastics play a crucial role in our daily lives. The challenge, however, is that they become waste and contribute to a global environmental problem, increasing concerns about pollution and the urgent need to protect the environment. The accumulation and fragmentation of plastic waste, especially micro- and nanoplastics in aquatic systems, poses a significant threat to ecosystems and human health. In this study, the decomposition and fragmentation processes of conventional and biobased plastic waste in simulated water bodies (waters with different pH values) and in real water systems (tap water and seawater) are investigated over a period of one and six months. Three types of plastic were examined: thermoplastic polyethylene terephthalate and thermoset melamine etherified resin in the form of nonwovens and biobased polylactic acid (PLA) in the form of foils. Such a comprehensive study involving these three types of plastics and the methodology for tracking degradation in water bodies has not been conducted before, which underlines the novelty of the present work. After aging of the plastics, both the solid fraction and the leachate in the liquid phase were carefully examined. The parameters studied include mass loss, structural changes and alterations in functional groups observed in the aged plastics. Post-exposure assessment of the fragmented pieces includes quantification of the microplastic, microscopic observations and confirmation of composition by in situ Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy. The leachate analysis includes pH, conductivity, turbidity, total carbon and microplastic size distribution. The results highlight the importance of plastic waste morphology and the minor degradation of biobased PLA and show that microfibers contribute to increased fragmentation in all aquatic systems and leave a significant ecological footprint. This study underlines the crucial importance of post-consumer plastic waste management and provides valuable insights into strategies for environmental protection. It also addresses the pressing issue of plastic pollution and provides evidence-based measures to mitigate its environmental impact. Graphical abstract

Chemical recycling of post-consumer polyester wastes using a tertiary amine organocatalyst

Chemical recycling of post-consumer polyester wastes using a tertiary amine organocatalyst

Enlisting the work of boundaries and boundary objects in shaping apartment waste

Recycling in apartments has been problematised around the world, as this housing typology is associated with relatively low resource recovery rates. Rather that assuming that occupant behaviours are the key concern, this paper starts with the observation that apartments are sites of unevenly distributed spatialities and responsibilities. They co-shape material and infrastructural affordances and call upon diverse knowledge of waste management in collective and shared arrangements. This paper analyses data from an in-depth qualitative study involving apartment waste and apartment households in Melbourne, Australia. It shows that boundaries and boundary objects help define waste and its relationships, mutually shaping and being shaped by material flows and reconfiguring responsibilities. The co-production of these boundaries and boundary objects is correlated to mechanisms of governance, regulations, assumptions associated with verticality/shared living, and seasonality. In the context of post-consumer waste recovery policy ambitions, the paper illustrates how a) shifting boundaries to redistribute responsibility b) engaging with somatic work to bridge boundaries that challenge material flows, and c) harnessing boundaries that nurture and normalize sustainable waste practices, can be potential sites of intervention. As a theoretical contribution, it draws upon boundary work and social practices as a novel way to inform interventions to promote sustainability.

Aplicações da nanotecnologia em embalagens inteligentes para alimentos

The growing demand for food has contributed to the increase in plastic waste, mainly from packaging. In 2020, only 23.1% of post-consumer plastic waste was recycled in Brazil, resulting in a significant amount of non-biodegradable waste that remains in the environment for long periods, affecting human health and the environment. Most of this waste comes from traditional petroleum-based food packaging, such as polyethylene, polypropylene, and polystyrene. It is estimated that annually, 31.9 million tons of plastic waste enter the environment, with a considerable portion contaminating the oceans. Despite these environmental challenges, the demand for plastics is expected to continue to grow to meet society's resource-efficient needs (FERREIRA et al., 2022).

Recirculating frass from food waste bioconversion using black soldier fly larvae: Impacts on process efficiency and product quality

Biowaste generation is increasing worldwide and inadequate disposal has strong negative impacts on food systems and ecosystems. Biodigestion of biowaste using black soldier fly (Hermetia illucens) larvae (BSFL) generates valuable by-products such as animal feed (larval biomass) and organic fertiliser (frass). However, the latter is typically unstable immediately after waste conversion and is thus unsafe for use as a fertilizer in terms of maturity. This study evaluated recirculation of frass within bioconversion of post-consumer food waste (FW) as a dietary component for BSFL to improve the quality of the subsequent frass obtained. Frass was introduced at increasing inclusion levels replacing food waste (2.5–100% on wet-weight basis) as part of the larvae's feeding substrate. Bioconversion efficiency and material reduction were significantly reduced by frass inclusion, while larval yield per experimental unit remained unchanged. When considering only the waste component in the larval diet, larval yield (dry-weight basis) ranged between 207 (0% frass inclusion) and 403 (40% frass inclusion) kg tonne FW−1, thus increasing by up to 94% at higher frass inclusion. With increasing dietary inclusion rate of frass from 0% to 100%, crude protein content of larval biomass increased by 41%, while fat content was reduced by 32%. The recirculated frass (obtained after including frass in the larval diet) had elevated concentrations of P, K, S, Na and B and around 6% lower organic matter content, demonstrating a higher degree of decomposition. Frass inclusion in the larval diet generated recirculated frass that were more stable and mature, as indicated by self-heating capacity, CO2 and NH3 volatilisation, seed germination bioassays and other parameters. It was concluded that frass recirculation improves waste bioconversion efficiency in relation to food waste unit, as well as larval biomass and frass quality, ensuring safer use as a fertilizer.

Sustainable and multifunctional polyurethane green composites with renewable materials

Polyurethane materials are characterised by an ever-expanding range of application possibilities due to their versatility. Currently, the management of leftovers as well as post-production and post-consumer waste for the production of biocomposites is one of the most obvious, effective and profitable solutions. Due to the renewable nature of biofillers such as cellulose, lignin, and chitin, their use to obtain composite polyurethane elastomers is a real perspective for the dissemination of more environmentally friendly materials and, at the same time, contributes to additional economic profit. The key aspect for further development of the polyurethane/biopolymer biocomposite concept is to fulfil of a number of currently functioning industry standards, mainly those regarding functional properties. In the presented research, an attempt to obtain advanced polyurethane elastomers with the addition of biopolymers (cellulose, lignin, and chitin) was conducted for the first time. The innovative biocomposites obtained in this way were characterised by good processing parameters (processing times, density) and improved functional properties compared to the standard without the addition of fillers (abrasion resistance, tensile strength, contact angle, hardness). Due to the above-mentioned facts, the described biocomposites can be successfully used for the production of multifunctional elastomeric materials with a wide range of potential applications. Moreover, it is worth noting that the management of waste materials in this way will reduce production costs while indirectly contributing to the protection of the natural environment.Graphical abstract

Transforming a mixture of real post-consumer plastic waste into activated carbon for biogas upgrading

Plastic waste management is a current environmental issue that demands potential solutions since complete mechanical recycling is limited to the complexity and feasibility regarding the quality and purity of plastic waste. Pyrolysis has emerged as a reasonable solution for the recycling of those fractions that are not further suitable for recycling. Although the implementation of this technology is mature, the generated solid fraction or char has not been completely inserted in the closed loop of plastic recycling. This work explores the possibility of using the carbonaceous char as a precursor for the preparation of porous activated carbons for environmental application as CO2 adsorbent and biogas upgrading. The effect of the pyrolysis temperature (450 or 500 ºC) on the obtained chars has been assessed for the benefits in the second stage of chemical activation, exploring the possibility of the use of diverse chemical agents. The composition, textural, and surface properties of the porous materials were characterized. N2 isotherms showed that the char prepared at 500 ºC provided the best textural properties with a performance of K2CO3 ∼ KOH > Na2CO3 > NaOH > ZnCl2 > FeCl3. Isotherms of CO2 adsorption showed that the activation with K2CO3 displayed the best uptake (130.2 mg g−1 at 273 K), closely followed by KOH (125.0 mg g−1 at 273 K), also confirmed by dynamic tests in a fixed bed column configuration. The uptake was well correlated with the ultramicropore volume and the oxygenated functional groups. The CO2 and CH4 adsorption were studied either in static or dynamic assays. The behavior of the sample activated with K2CO3 was studied in detail in column tests, suggesting that the activated material exhibits promising behavior for biogas upgrading.

Evaluating the economic and environmental benefits of deploying a national-scale, thermo-chemical plastic waste upcycling infrastructure in the United States

Emerging chemical technologies can upcycle plastic waste by producing high-value polymers and other products. In this work, we study the economic and environmental benefits of deploying an upcycling infrastructure in the continental United States for producing low-density polyethylene (LDPE) and polypropylene (PP) from post-consumer plastic waste. Our analysis is based on a computational framework that integrates techno-economic analysis, life-cycle assessment, and value chain optimization. Our results demonstrate that the infrastructure could generate a market of nearly 20 billion USD per year and that this market is robust to various externalities. Our analysis also indicates that the infrastructure can achieve a plastic-to-plastic degree of circularity of 34% relative to residential plastic waste production, and leads to significant environmental benefits over alternative waste disposal methods, including 69%–75% lower greenhouse gas emissions than waste-to-energy systems and 38 million tonnes of avoided landfill waste per year.

Stapler Strategies for Upcycling Mixed Plastics.

Mechanical recycling is one of the simplest and most economical strategies to address ever-increasing plastic pollution, but it cannot be applied to immiscible mixed plastics and suffers from property deterioration after each cycle. By combining the amphiphilic block copolymer strategy and reactive compatibilization strategy, we designed a series of stapler strategies for compatibilizing/upcycling mixed plastics. First, various functionalized graft copolymers were accessed via different synthetic routes. Subsequently, the addition of a very small amount of stapler molecules induced a synergistic effect with the graft copolymers that improved the compatibility and mechanical properties of mixed plastics. These strategies were highly effective for various binary/ternary plastic systems and can be directly applied to postconsumer waste plastics, which can increase the toughness of mixed postconsumer waste plastics by 162 times. Most importantly, it also effectively improved the impact resistance, adhesion performance, and three-dimensional (3D) printing performance of mixed plastics, and permitted the recycling of plastic blends 20 times with minimal degradation in their mechanical properties.

Identification of the recyclable content of polyethylene films in the Upper Austrian waste streams

ABSTRACT The European Union (EU) has set ambitious recycling targets for plastic packaging waste of 50% and 55% by the end of 2025 and 2030, respectively. Austria’s recycling rate is currently below 30%, necessitating significant improvements in collection, sorting, and recycling efficiencies. To enhance the sorting efficiency, understanding the composition and condition of waste is crucial. Our study focuses on the identification of the recyclable content of polyethylene (PE) films in Upper Austrian waste streams for plastics recycling. This involved the manual sorting of three waste streams through various steps. As a result, the occurrences of monolayer PE films in the post-consumer waste streams were obtained. Based on the apprehended data, a circularity indicator (CI), which is a rough estimation of material circularity that takes into account the losses in both quantity and quality when reprocessing materials, together with a sensitivity analysis was calculated for Austria, which revealed that reducing demand and increasing the amount of recycled materials is more beneficial to the CI than improving energy efficiency. This research fills knowledge gaps on the availability of PE film waste in the various waste streams and can be used as a basis for enhancing the recycling rate in PE film recycling.

Enhanced degradation of post-consumer polyethylene terephthalate (PET) wastes by fusion cutinase: Effects of anchor and linker peptides

Enzymatic degradation of poly(ethylene terephthalate) (PET) into its corresponding monomers provides an attractive route for green plastic recycling and environmental remediation applications. However, the binding of PET hydrolases toward the PET surface is a rate-limiting step in PET degradation. Hence, we selected three anchor peptides and four linker peptides to fuse the previously engineered leaf-branch compost cutinase for facilitating enzyme binding and improving degradation of real post-consumer PET wastes of Coca Cola and C′eastbon PET bottles, with using the amorphous PET as a control. The systematical characterization of the seven cutinases revealed that the anchor peptide with moderate hydrophobicity plus chaperone activity and the flexible linker peptide with small hydrophobicity but long length were more suitable for each domain to serve its own role, affording the facilitated PET binding affinities and enhanced PET degradation performance. Thus, the optimal fusion cutinase possessed up to 3.3 times higher catalytic efficiency (kcat/Km) and 76 % increased long-term degradation performance than the parental cutinase, respectively. Further, complete degradation of C′eastbon PET wastes and 77 % degradation of Coca Cola PET wastes were achieved by the optimal cutinase of 33.3 nmol·g−1PET in 96 h, proving its superiority against the real post-consumer PET wastes.

Innovative biorefinery approaches for upcycling of post-consumer food waste in a circular bioeconomy context

Owing to the significant amounts produced each year, food waste is a critical issue that affects the economy, society, and environment. An estimated US$ 1 trillion food is wasted annually because of the supply chain and harvesting processes, which lose around one-third of the net production. This significant loss has sparked global concern, there is an urgent need for sustainable approaches to reduce food waste or to propose an economical route for its utilization. Major concerns associated with its improper management include environmental degradation and the exacerbation of greenhouse gases. This review provides a comprehensive understanding of the recent advances in measures to minimize food waste (FW) and its chemical and biotransformation into valuable products. Food waste comprises mainly carbohydrates, proteins, and oils; the former two components are commonly used as microbial feedstock, leaving behind the residual oil fraction which poses a greater environmental risk. Microbial transformation of these hydrophobic materials present in food waste into value-added products proves to be a sustainable and economical strategy. Thus, this study proposes an integrated biorefinery strategy for holistic valorization of FW, whereby all its components were used to produce value-added compounds such as biofuels, bioplastics, nutraceuticals, and biomaterials using microbial biocatalysis. Compared to conventional methods, an integrated biorefinery will be more sustainable and uplift the microbial processes by switching from ‘pure’ to food waste-derived substrates and thereby pave ways to achieve ‘green’ transition.

Assessment of demographics and motivations of post-consumer textile waste management using a bibliometric approach

Assessment of demographics and motivations of post-consumer textile waste management using a bibliometric approach

Optimization of Pressurized Alkaline Hydrolysis for Chemical Recycling of Post-Consumer PET Waste.

Addressing the environmental impact of poly(ethylene terephthalate) (PET) disposal highlights the need for efficient recycling methods. Chemical recycling, specifically alkaline hydrolysis, presents a promising avenue for PET waste management by depolymerizing PET into its constituent monomers. This study focuses on optimizing the pressurized alkaline hydrolysis process for post-consumer PET residues obtained from packaging materials. Post-consumer PET packaging waste was chemically recycled by means of an alkaline hydrolysis reaction in a 2 L pressurized reactor under varying conditions of the NaOH/PET ratio and temperature. The reaction's progress was monitored by sampling the liquid phase hourly over a four-hour period. The obtained products were purified, with a focus on isolating terephthalic acid (TPA). Higher temperatures (150 °C) resulted in superior TPA yields (>95%) compared to lower temperatures (120 °C). The NaOH/PET ratio showed minimal influence on the TPA yield. The optimal conditions (T = 150 °C; NaOH:PET = 2) were identified based on TPA yield and reaction cost considerations. This study demonstrates the feasibility of pressurized alkaline hydrolysis for PET recycling, with optimized conditions yielding high TPA purity and efficiency.

Deconstruction of Polymers through Olefin Metathesis.

The consumption of synthetic polymers has ballooned; so has the amount of post-consumer waste generated. The current polymer economy, however, is largely linear with most of the post-consumer waste being either landfilled or incinerated. The lack of recycling, together with the sizable carbon footprint of the polymer industry, has led to major negative environmental impacts. Over the past few years, chemical recycling technologies have gained significant traction as a possible technological route to tackle these challenges. In this regard, olefin metathesis, with its versatility and ease of operation, has emerged as an attractive tool. Here, we discuss the developments in olefin-metathesis-based chemical recycling technologies, including the development of new materials and the application of olefin metathesis to the recycling of commercial materials. We delve into structure-reactivity relationships in the context of polymerization-depolymerization behavior, how experimental conditions influence deconstruction outcomes, and the reaction pathways underlying these approaches. We also look at the current hurdles in adopting these technologies and relevant future directions for the field.

Feasibility study on the production of low melt flow rate recycled polypropylene from postconsumer waste

AbstractPolypropylene (PP) recyclates face limitations in their use due to lower qualities compared with virgin PP, resulting from contaminations and the mixing of different PP grades. In particular, their high melt flow rate (MFR) hinders their suitability for applications requiring low MFR, such as pipes. This study investigates the feasibility of producing low MFR PP recyclates from packaging waste. For this purpose, recyclates were produced exclusively from manually sorted extrusion blow molding grades and compared with a recyclate derived from a conventional PP waste stream. Different washing temperatures and recyclate production processes were used to study their effects on the properties of the recyclates. The main objective was to determine the lowest achievable MFR and the rheological, mechanical, and thermal properties of the recyclates from improved sorting. The results are intended to serve as reference points for the evaluation of future automatic sorting trials. The enhanced sorting resulted in an 80% reduction in the MFR and improved ductility, thereby extending the potential applications of the recyclate. The different washing and production processes did not have a significant effect on the investigated properties, except for a slight decrease in the MFR with hot washing and the omission of the pelletizing step.

Enabling plastic waste gasification by autothermal chemical looping with > 90 % syngas purity for versatile feedstock handling

The chemical looping gasification of plastics (CLGP) is a process that offers an innovative solution for transforming post-consumer waste plastics into high-value products. The process utilizes a co-current moving bed reducer reactor with iron-titanium-based oxygen carriers to gasify plastic feed and generate syngas autothermally. Its distinguishing feature is its ability to operate over a wide range of feed loadings and co-injection of mixed plastic species without any performance losses. Isothermal bench-scale experiments reveal a syngas purity of ∼95 %, aligning with the thermodynamic simulations. The moving bed reactor facilitates a deeper reduction of the oxygen carriers to the Fe+FeTiO3 phase, leading to the high syngas purity, which is then verified with additional TGA, XRD, and SEM analysis. For an autothermal operation of CLGP process, an active material content of 20 % is found to be sufficient to satisfy the kinetic and thermodynamic constraints. Further integration with downstream production of H2 is presented and compared to a steam gasification process. The process integration simulations show that the CLGP process outperforms the steam gasification system in terms of Cold Gas Efficiency (CGE), Effective Thermal Efficiency (ETE), and H2 yield. CO2 emissions are impressively reduced by ∼30 % in the CLGP system over that in the steam gasification system due to its ability to autothermally operate the process, unlike the highly endothermic steam gasification process.

One-Pot Biosynthesis of Acetone from Waste Poly(hydroxybutyrate).

The plastic waste crisis is catalyzing change across the plastics life cycle. Central to this is increased production and application of bioplastics and biodegradable plastics. In particular, poly(hydroxybutyrate) (PHB) is a biodegradable bioplastic that can be produced from various renewable and waste feedstocks and is a promising alternative to some petrochemical-derived and non-biodegradable plastics. Despite its advantages, PHB biodegradation depends on environmental conditions, and the effects of degradation into microplastics, oligomers, and the 3-hydroxybutyrate (3-HB) monomer on soil microbiomes are unknown. We hypothesized that the ease of PHB biodegradation renders this next-generation plastic an ideal feedstock for microbial recycling into platform chemicals currently produced from fossil fuels. To demonstrate this, we report the one-pot degradation and recycling of PHB into acetone using a single strain of engineered Escherichia coli. Following strain development and initial bioprocess optimization, we report maximum titers of 123 mM acetone (7 g/L) from commercial PHB granules after 24 h fermentation at 30 °C. We further report biorecycling of an authentic sample of post-consumer PHB waste at a preparative scale. This is the first demonstration of biological recycling of PHB into a second-generation chemical, and it demonstrates next-generation plastic waste as a novel feedstock for the circular bioeconomy.