Search Results (3,261)

Polyethylene is the most used plastic in the world, and over 90% of this plastic is ultimately disposed of in landfills or released into the environment, leading to severe ecological implications. In this research, the technoeconomic feasibility of upcycling low-density polyethylene (LDPE) to produce ethylene is studied. The catalytic conversion of LDPE to ethylene is considered in microwave heating mode and Joule heating mode. Experimental data is obtained under conditions where most of the upcycled products are in the gas phase. A flowsheet is developed that produces industrial quantities of ethylene for both heating modes. A technoeconomic analysis and a life cycle analysis are conducted and compared with the traditional ethane cracking process for producing ethylene. Simulation results indicate that the upcycling system exhibits a lower capital expenditure and a comparable operating expenditure relative to conventional ethane steam cracking while generating additional valuable co-products, such as propylene and aromatic hydrocarbons, leading to a higher net present value potential. Sensitivity analyses reveal that the electricity price has the most significant impact on both the net present value and levelized cost of production, followed by the low-density polyethylene feedstock cost. Life-cycle assessment reveals a substantial reduction in greenhouse-gas emissions in the upcycled process compared to the fossil-based ethane steam-cracking route, primarily due to the use of renewable electricity, the lower reaction temperature that reduces utility demand, and the use of plastic waste as the feedstock. Overall, the proposed process demonstrates strong potential for the sustainable production of ethylene from waste LDPE. Full article

Waste electrical and electronic equipment (WEEE) is one of the fastest-growing waste streams globally. Disposable e-cigarettes are among the products that have gained popularity in recent years. Their complex construction and embedded lithium-ion batteries (LIBs) present environmental, safety, and resource recovery challenges. Despite growing research interest, integrated analyses linking material composition with user disposal behavior remain limited. This study is the first to incorporate device-level mass balance, material contamination assessment, battery residual charge measurements, and user behavior to evaluate the waste management challenges of disposable e-cigarettes. A mass balance of twelve types of devices on the Polish market was performed. Plastics dominated in five devices, while non-ferrous metals prevailed in the others, depending on casing design. Materials contaminated with e-liquid residues accounted for 4.4–10.7% of device mass. Battery voltage measurements revealed that 25.6% of recovered LIBs retained a residual charge (greater than 2.5 V), posing a direct fire hazard during waste handling and treatment. Moreover, it was estimated that 7 to 12 tons of lithium are introduced annually into the Polish market via disposable e-cigarettes, highlighting substantial resource potential. Survey results showed that 46% of users disposed of devices in mixed municipal waste, revealing a knowledge–practice gap largely independent of gender or education. Integrating technical and social findings demonstrates that improper handling is a systemic issue. The findings support the relevance of eco-design requirements, such as modular casings for battery removal, alongside the enforcement of Extended Producer Responsibility (EPR) schemes. Current product fees (0.01–0.03 EUR/unit) remain insufficient to establish an effective collection infrastructure, highlighting a key systemic barrier. Full article

Today, PHB and its copolymers—potential plastic substitutes—are produced by fermenting sugar, which is not scalable to the volumes of plastic consumption. PHB from CH₄ can offer a sustainable process route, with CH₄ potentially produced from a variety of waste biomass streams through anaerobic digestion, gasification, and methanation. The high molar mass (M_w) of PHB is a key determinant of its mechanical properties, and strain, culture conditions and downstream processing influence it. In this work, the strain Methylocystis sp. GB 25 (DSMZ 7674) was grown on natural gas as the sole carbon and energy source and air (1:1) in a loop reactor with 350 L active fermentation volume, at 35 °C and ambient pressure. After two days of continuous growth, the bacteria were limited in P and N for 1, 2, and 2.5 days to determine the optimal conditions for PHB accumulation and the highest Mw as the target. The biomass was then centrifuged and spray-dried. For downstream processing, chloroform solvent extraction and selected enzymatic treatment were deployed, yielding ~40% PHB from the biomass. The PHB obtained by solvent extraction exhibited high average weight molar masses of M_w ~1.1–1.5 × 10⁶ g mol⁻¹. The highest M_w was obtained after one day of limitation, whereas enzyme treatment resulted in partially degraded PHB. Cold chloroform maceration, interesting due to energy savings, did not achieve sufficient extraction efficiency because it was unable to extract high-molar-mass PHB fractions. The extracted PHB has a high molar mass, more than double that of standard commercial PHB, and was characterized by DSC, which showed a high degree of crystallinity of up to 70% with a melting temperature of close to 180 °C. Mechanical tensile properties measurements, as well as dynamic mechanical thermal analysis (DMTA), were performed. Degradation of the PHB by enzymes was also determined. Methanotrophic PHB is a promising bioplastics material. The high M_w can limit and delay polymer degradation in practical processing steps, making the material more versatile and robust. Full article

This work evaluated the effect of coffee oil epoxide (COE), produced from coffee waste, on thermal, mechanical, barrier, and exudation resistance properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/natural rubber (PHBV/NR) blends. Building upon previously published 0.3% COE results, this study examined 0.4% and 0.75% concentrations to optimize performance. Thermal analysis revealed that COE incorporation significantly enhanced chain mobility, with glass transition temperature depressions of 6.1 °C and 7.4 °C for 0.4% and 0.75% COE formulations, respectively, compared to unplasticized PHBV/NR blends. Crystallinity decreased from 54.5% (PHBV/NR) to 52.6% and 51.9% with increasing plasticizer concentration, while melting temperatures decreased by 3.9% and 4.9%, confirming improved polymer chain mobility. Mechanical properties demonstrated COE’s plasticizing effectiveness, with tensile strength decreasing by 13.3% (0.4% COE) and 16.2% (0.75% COE) compared to PHBV/NR blends. Young’s modulus similarly decreased by 21.0% and 24.0%, while elongation at break improved slightly with increasing COE content. Barrier properties improved substantially across all concentrations: water vapor transmission rates decreased from 4.05 g/m²·h (PHBV/NR) to 1.55 g/m²·h (0.3% COE) and 0.67 g/m²·h for 0.4% and 0.75% COE, attributed to COE’s hydrophobic nature. SEM morphological analysis confirmed improved phase compatibility at 0.40% COE, with reduced rubber droplet size and homogeneous surface morphology. Exudation testing revealed excellent retention (0.21–0.53 wt% loss over 63 days). Results indicate 0.40% COE as optimal, achieving superior barrier properties while maintaining mechanical performance for sustainable packaging applications. Full article

Polyester fibers are extensively used in textiles, packaging, and industrial applications due to their durability and excellent mechanical properties. However, high-crystallinity polyester fibers represent a major challenge in plastic waste management due to their resistance to biodegradation. This study evaluated the biodegradation potential of environmental Bacillus isolates, obtained from mold-contaminated black bean plastic bags, toward polyethylene terephthalate (PET) and industrial-grade polyester fibers under mesophilic conditions. Among thirteen isolates, five (Bacillus altitudinis N5, Bacillus subtilis N6, and others) exhibited measurable degradation within 30 days, with mass losses up to 5–6% and corresponding rate constants of 0.04–0.05 day⁻¹. A combination of complementary characterization techniques, including mass loss analysis, scanning electron microscopy (SEM), gel permeation chromatography (GPC), and gas chromatography/mass spectrometry (GC/MS), together with Fourier-transform infrared spectroscopy (FTIR), thermogravimetric/differential scanning calorimetry (TGA/DSC), and water contact angle (WCA) analysis, was employed to evaluate the biodegradation behavior of polyester fibers. Cross-analysis of mass loss, surface morphology, molecular weight reduction, and degradation products suggests a surface erosion-dominated degradation process, accompanied by ester-bond hydrolysis and preferential degradation of amorphous regions. FTIR, TGA/DSC, and WCA analyses further reflected chemical, thermal, and surface property changes induced by biodegradation rather than directly defining the degradation mechanism. The findings highlight the capacity of mesophilic Bacillus species to partially depolymerize polyester fibers under mild environmental conditions, providing strain resources and mechanistic insight for developing low-energy bioprocesses for polyester fiber waste management. Full article

The utilization of sustainable feedstocks offers significant opportunities for innovation in sustainable and efficient processing technologies, targeting a vacuum residue upgrade industry projected to be valued at around USD 26 billion in 2024. This review examines advances in catalytic strategies for upgrading waste-derived products (plastics, tires) and biomass, in addition to heavy oil feedstocks. Particular emphasis is placed on hydrogen addition pathways, specifically, residue hydroconversion facilitated by dispersed nanocatalysts and waste co-processing methodologies. Beyond nanoscale catalyst design and reaction performance, this work also addresses refinery-level sustainability impacts. The advanced catalytic conversion of heavy oil residue demonstrates superior conversion efficiency, significant coke suppression, and improved carbon utilization, while life cycle and illustrative techno-economic comparisons indicate greenhouse gas reductions and a net economic gain of approximately USD 2–3 per barrel relative to conventional refining under scenarios assuming decarbonized hydrogen production. Co-processing of plastics, tires, and biomass with heavy oil feedstocks is highlighted as a practical and effective approach. Together, these findings outline a rational catalytic pathway toward optimized refining systems. Within the framework of the circular carbon economy, these catalytic processes enable enhanced feedstock utilization, integration of low-carbon hydrogen, and coupling with carbon-capture technologies. Full article

Fast-growing invasive tree species management produces a significant amount of low-density and low-value biomass, which offers a chance for waste valorization in the environmentally friendly construction sector. This study examines the utilization potential of low-value natural waste materials of tree bark, obtained from invasive hardwood species, in the production of environmentally friendly building mortars. More specifically, this study focuses on mixing bark powder of black locust (Robinia pseudoacacia L.) and tree-of-heaven (Ailanthus altissima (Miller) Swingle), with two commercial commonly found lime-based mortar powders in five different ratios of bark content (0%, 5%, 10%, 20% and 30%) characterizing the produced composites, in terms of physical, hygroscopic and mechanical properties. Slightly lighter composites were created with the use of bark additives especially at the bark content of 20% and 30%. As regards the compressive strength, the bark shares of 10% and 20% exhibited the most beneficial performance among those studied, though only the weaker performance of mortar type (M1) benefited significantly from bark incorporation. For both mortars, the composites containing black locust bark presented higher resistance to compression strength and elasticity, demonstrating higher composite integration in general and milder, plastic fraction in relation to tree-of-heaven bark-based specimens, the properties of which are considered crucial for the durability of structural materials. However, black locust bark exhibited higher water absorption compared to tree-of-heaven-based specimens. Despite the drawback of higher hygroscopicity, the results show that black locust bark, especially at lower incorporation rates (10–20%), is a promising functional additive for generating lighter, more ductile mortars, supporting the creation of novel building materials and sustainable waste management. Full article

Plastic waste is a global issue due to the popularity of the product. Over time, plastic degrades into smaller particles known as microplastics and becomes harder to deal with as it easily disperses and can be missed by physical catches. Conventional degradation involves environmental forces like ultraviolet (UV) light, water, temperature, and physical abrasion. However, there is increasing interest in microbial plastic degradation, which could positively impact the transformation of (micro)plastics in various environmental matrices. Most of the available research has focused on bacterial degradation, but there is mounting evidence on the impact of fungal degradation. This review discusses conventional and bacterial degradation, then discusses the advantages of fungal involvement in the degradation of microplastics. Biodegradation enhanced by fungal enzymes is a valuable tool that could greatly improve the removal of these microplastic pollutants from the environment. Due to some biochemical complexities, fungi are naturally omnipresent in marine and terrestrial environments under all sorts of climates. Fungi could thrive by themselves or in association with other microorganisms, which could also be applied in non-biotic plastic degradation processes as an alternative to other forms of plastic management in the environment. Full article

Refractory geopolymers derived from aluminosilicate sources and alkaline activation are a promising alternative to traditional fired bricks, particularly when low-cost, waste-derived raw materials are used. This study improves the workability of a refractory brick formulated with clays (Kaolin and Tepozan–Bauwer), seashell waste, sodium silicate, potassium hydroxide, and water by incorporating sodium lignosulfonate (LS) and polycarboxylate (PC) plasticizers. Clays from Comonfort, Guanajuato, Mexico, and seashells were ground and sieved to pass a 100 Tyler mesh. A base mixture was prepared and evaluated using the Mini Slump Test, varying plasticizer content from 0 to 2% relative to the solid fraction. Based on workability, 0.5% LS and 1% PC (by solids) increased the slump, and a blended plasticizer formulation (1.5% by solids, 80%PC+20%LS) produced the highest workability. These additives act through different mechanisms, with LS primarily promoting electrostatic repulsion and PC steric repulsion. Bricks with and without plasticizers exhibited thermal resistance up to 1200 °C. After four calcination cycles, compressive strength values were 354.74 kg_f/cm² for the brick without plasticizer, 597.25 kg_f/cm² for 1% PC, 433.63 kg_f/cm² for 0.5% LS, and 519.05 kg_f/cm² for 1.5% of the 80%PC+20%LS blend. Strength was consistent with changes in porosity and apparent density, and 1% PC provided a favorable combination of high workability and high compressive strength after cycling. Because the cost of clays and seashells is negligible, formulation selection was based on plasticizer cost per brick. Although 1% PC and the 1.5% of 80%PC+20%LS blend showed statistically comparable strength after cycling, 1% PC was selected as the preferred option due to its lower additive cost ($0.0449 per brick) compared with the blend ($0.0633 per brick). Stereoscopic microscopy indicated pore closure after calcination with no visible cracking, and SEM–EDS identified O, Si, and Al as the significant elements, with traces of S and K. Overall, the study provides an integrated assessment of workability, multi-cycle calcination, microstructure, and performance for refractory bricks produced from readily available clays and seashell waste. Full article

Packaging plays a crucial role in product preservation and distribution but also constitutes a major source of environmental burden. In the beverage sector, where unit value is low, secondary and tertiary packaging significantly influence the environmental profile of the final product. This study quantifies the environmental trade-offs between conventional single-use and reusable packaging systems for aluminum cans, identifying the operational thresholds that justify a transition to circular models. A standardized Life Cycle Assessment (LCA) approach is applied to five packaging configurations: three current market scenarios and two alternative solutions based on reusable plastic crates (RPCs). System boundaries include production, distribution, end-of-life, and, where applicable, reverse logistics. A functional unit of one fully packaged 0.33 L aluminum can is adopted. Results reveal that while single-use cardboard solutions achieve favorable performance under certain impact categories, reusable systems outperform them when a sufficient number of reuse cycles is achieved and reverse logistics are efficiently managed. Sensitivity analyses highlight the critical influence of transport distances and reuse frequency on overall impacts, with performance deteriorating for reusable systems beyond 200 km or below 50 reuse cycles. These findings offer concrete, evidence-based guidance for supply-chain and logistics decision-makers to optimize packaging choices and distribution network design. The study also provides robust quantitative insights for policymakers and industry stakeholders by defining the precise operational conditions under which reusable systems deliver real environmental benefits. By presenting a comprehensive, system-level comparison of complete packaging systems, this research closes a critical gap in LCA studies and sets out a practical pathway for implementing circular, low-impact packaging strategies consistent with emerging EU regulations. Full article

To address the dual challenges of improving precast cable trench joint performance and promoting solid waste recycling for carbon neutrality, this study developed a jute fiber-reinforced recycled aggregate concrete (JFRAC) and established a complete technical chain via experiments and numerical simulations. Compressive strength tests were conducted on JFRAC with varying jute fiber volume content and recycled coarse aggregate (RCA) replacement ratio to obtain their influence on the stress–strain relationship. A modified Concrete Damaged Plasticity (CDP) model was proposed by introducing correction coefficients for compressive strength and elastic modulus, achieving over 95% agreement with experimental data. Finite element simulations of cable trench joints showed that JFRAC outperforms C30 concrete, with the same compressive strength, in ultimate bearing capacity (↑4.17%), peak displacement (↑18.78%), and ductility (↑14.66%). JFRAC provides substantial environmental and economic advantages by reducing carbon emissions by 2.29% and saving costs of CNY 62.43 per meter of precast cable trench. Parametric studies indicated bolt grade and number are the primary performance influencers. Bolt grade’s impact diminishes as it increases from 8.8 to 10.9, while bolt number linearly enhances load-bearing capacity. This study provides a feasible path for JFRAC to replace conventional concrete in cable trenches, realizing both economic and environmental benefits. Full article

The rapid growth of online food delivery in urban areas reflects changing consumer lifestyles, but it has also contributed to increasing plastic waste and challenges in waste management. This study investigated the composition of municipal solid waste (MSW) related to online food delivery, consumer ordering behavior, and single-use plastic (SUP) generation in households in the Bangkok Metropolitan Area. Data were collected from 385 food delivery customers via online questionnaires. The results show that the proportion of plastic waste in MSW has increased, with 76.6% of participants reporting higher online food delivery usage. SUPs from food delivery, including non-essential items such as plastic films, spoons, and cutlery, were prevalent, and participants rarely selected green options to opt out of receiving them. These findings highlight the need for targeted interventions, including closed-loop management involving producers, platforms, consumers, and government. Policy recommendations include implementing extended producer responsibility (EPR) for environmentally friendly packaging, providing incentives for merchants and consumers to reduce SUP, applying the polluter-pays principle (PPP) to users, and designing government policies to regulate SUP and improve plastic waste management. Full article

The Citarum River Basin (DAS Citarum) in Indonesia faces significant challenges in waste management, necessitating a circular economy-based approach to reduce land-based pollution, which is critical for achieving the sustainability goals of the blue economy in the basin. This study addresses the complexity and inherent uncertainty in decision-making processes related to this challenge by developing a novel hybrid model, namely the Weighted Fuzzy N-Soft Set combined with the COmbinative Distance-based Assessment (CODAS) method. The model synergistically integrates the weighted 10R strategies in the circular economy, obtained via the Analytical Hierarchy Process (AHP), the capability of Fuzzy N-Soft Sets to represent uncertainty granularly, and the robust ranking mechanism of CODAS. Applied to a case study covering 16 types of waste in the Citarum River Basin, the model effectively processes expert assessments that are ambiguous regarding the 10R criteria. The results indicate that single-use plastics, particularly plastic bags (HDPE), styrofoam, transparent plastic sheets (PP), and plastic cups (PP), are the top priorities for intervention, in line with the high AHP weights for upstream strategies such as Refuse (0.2664) and Rethink (0.2361). Comparative analysis with alternative models, namely Fuzzy N-Soft Set-CODAS, Weighted Fuzzy N-Soft Set with row-column sum ranking, and Weighted Fuzzy N-Soft Set-TOPSIS, confirms the superiority of the proposed hybrid model in producing ecologically rational priorities, free from purely economic value biases. Further sensitivity analysis shows that the model remains highly robust across various weighting scenarios. This study concludes that the WFN-SS-CODAS framework provides a rigorous, data-driven, and reliable decision support tool for translating circular economy principles into actionable waste management priorities, directly supporting the restoration and sustainability goals of the blue economy in river basins. The findings suggest that targeting the high-priority waste types identified by the model addresses the dominant fraction of riverine pollution, indicating the potential for significant waste volume reduction. This research was conducted to directly contribute to achieving multiple targets under SDG 6 (Clean Water and Sanitation), SDG 12 (Responsible Consumption and Production), and SDG 14 (Life Below Water). Full article

Polyhydroxyalkanoates (PHAs), a family of biodegradable polyesters produced through microbial fermentation of carbon-rich residues, are emerging as attractive alternatives to petroleum-based plastics. Their appeal lies in their exceptional biocompatibility, inherent biodegradability, and tunable physicochemical properties across diverse applications. These materials are environmentally friendly not just at the end of their life, but throughout their entire production–use–disposal cycle. This mini-review presents an update on the expanding biomedical relevance of PHAs, with emphasis on their utility in tissue engineering and drug delivery platforms. In addition, current clinical evaluations and regulatory frameworks are briefly discussed, underscoring the translational potential of PHAs in meeting unmet medical needs. As the healthcare sector advances toward environmentally responsible and patient-focused innovations, PHAs exemplify the convergence of waste valorization and biomedical progress, transforming discarded resources into functional materials for repair, regeneration, and healing. Full article

Smart packaging is an alternative that may not only replace plastic containers, but also enable food quality monitoring. In this study, an innovative packaging system was developed using a starch-chitosan polymer matrix, infused with rosemary essential oil (REO) as an antimicrobial agent, and betalain extract as a food quality indicator. Betalain extract, derived from beet waste, can change color with pH, making it a useful natural indicator for monitoring food freshness. This packaging system is beneficial for foods that produce metabolites related to degradation, which alter pH and allow for the visual detection of changes in product quality. The objective of this work was to develop a smart packaging system with betalains and rosemary essential oil (REO) to extend food shelf life and monitor quality during storage. REO demonstrated antimicrobial activity, but its effect did not differ significantly among the microorganisms tested. On the other hand, the betalain extract (35.75% BE v/v) completely inhibited the growth of Listeria innocua and Salmonella spp. at concentrations of 50% (v/v; 0.82 ± 0.04 mg betalain/g), showing its potential as an antimicrobial agent. The interactions between chitosan and betalains were primarily associated with electrostatic interactions between the positively charged amino groups of chitosan and the negatively charged carboxyl groups of betalains. In contrast to starch, these interactions could result from interactions between the C=O groups of betalain carboxyls and water, which, in turn, interact with the hydroxyl groups of starch through hydrogen bonding. Despite the results obtained in this study, certain limitations need to be addressed in future research, such as the variability in antimicrobial activity among different bacterial strains, which could reveal differences in the efficacy of betalains and essential oils against other pathogens. Full article