Search Results (30)

Waste polyethylene terephthalate (PET) from single-use bottles is generated in rapidly increasing quantities, yet only about 15–35% of PET bottles are recycled. A systematic search of four databases (Scopus, Web of Science Core Collection, Google Scholar and PubMed Central) returned 798 records; after duplicate removal and two-stage screening, 69 studies met the eligibility criteria, of which 28 reported the quantitative performance data that underpin the ranges extracted here. Three recycling routes were compared, namely mechanical recycling, chemical recycling (glycolysis, methanolysis, hydrolysis, pyrolysis and gasification) and enzymatic hydrolysis. PET has been added to concrete, asphalt, bricks, insulation and panels and tested for mechanical strength, physical behaviour and durability under laboratory conditions, and the associated microplastic release, leaching of antimony and phthalate plasticisers, and fire behaviour were also assessed. Costs and market barriers were examined. The evidence indicates that PET is suitable for non-structural and semi-structural applications, and that the reported dosage windows are application-specific rather than reducible to a single range: roughly 5–15% by volume as an aggregate replacement in concrete, 2–10% in asphalt on bases that differ between studies, 25–40% by mass in PET–sand bricks and 0.5–2% fibre volume fraction in fibre-reinforced mortar. Each window is an envelope across studies that differ in PET form, dosage basis, mix design and test standard, and none is a specification. Long-term field testing, standardised leaching and microplastic-release methods, and full life-cycle assessments remain the principal research and application gaps. By linking technical performance to environmental safety, evidence quality and market readiness, this review supports evidence-based decisions for sustainable, circular construction. Full article

Polyhydroxyalkanoates (PHAs) are a structurally diverse family of microbially synthesised, biodegradable polyesters that accumulate as intracellular carbon and energy reserves under conditions of nutrient imbalance. Their combination of adjustable mechanical performance with controlled hydrolytic and enzymatic degradation, and non-toxic degradation intermediates (ex. D-3-hydroxybutyrate) has made them a longstanding candidate biomaterial for human tissue engineering, drug delivery, and resorbable implants. Comparatively, their application in veterinary medicine remains an emerging and fragmented field, despite an arguably stronger practical case: veterinary practice faces acute pressure to replace non-degradable sutures, orthopaedic hardware, and single-use plastics with materials that avoid secondary retrieval surgery, that can be produced at low cost for large-scale animal use, and that align with growing regulatory and consumer demand for sustainable animal healthcare. This review consolidates current understanding of PHA biosynthesis, covering the core: phaA-phaB-phaC pathway, medium-chain-length variants, microbial producers, feedstock flexibility, and metabolic engineering strategies for yield improvement. It also examines material modification strategies, including blending, chemical grafting, surface functionalisation, electrospinning, and additive manufacturing, used to adapt PHAs for specific veterinary form factors. The clinical and preclinical evidence base is presented in detail across wound management, orthopaedic and soft-tissue regeneration, cardiovascular tissue engineering, drug delivery, and surgical devices, with attention to species-specific considerations in companion animals, horses, and food-producing ruminants. This review relies exclusively on peer-reviewed literature for its quantitative claims, while transparently noting where veterinary-specific data are lacking, extrapolated from rodent or human models, or in need of independent verification. Persistent barriers like production cost, batch-to-batch variability, absence of veterinary-specific regulatory pathways, and limited long-term in vivo safety data in large animals are analysed critically, alongside translational opportunities including waste-feedstock valorisation, hybrid PHA/ceramic and PHA/natural-polymer composites, and stimuli-responsive formulations. We conclude that PHAs are scientifically well positioned but institutionally under-validated for veterinary translation, and we outline a concrete research agenda to close this gap. Full article

Biocomposites reinforced with natural fibres are receiving increased attention due to growing concern over the environmental impacts of their synthetic counterparts. Grass mowed from roadside verges has the potential to serve as an alternative to commonly used natural fibres and as a renewable feedstock for the biocomposite industry. However, it is generally treated as waste due to its high volume, seasonal availability, contamination (e.g., with metals and plastic bottles), and legal status. In this study, a techno-economic assessment was performed for different roadside grass valorisation scenarios covering the entire value chain from mowing and pre-treatment to fibre and biocomposite granule production. In addition, a screening greenhouse gas emissions assessment based on the main energy and material inputs was performed for fibre production. This screening assessment provides an initial indication of the operational environmental performance and is not intended to represent a complete life cycle or integrated sustainability assessment. One scenario investigated a value chain with flail mowing and grass fibres as the final product. Grass fibres can be produced at €528/t when mowing costs are included and as low as €295/t when mowing costs are excluded under the processor/incremental-cost perspective. A reduction of 6.4% in fibre price was estimated for the rotary-mowing scenario when mowing costs were excluded. In comparison, the market price of commonly available natural fibres ranges from €300 to €4000/t, although the price is strongly dependent on fibre quality, which was not considered in this assessment. Another scenario considered biocomposite granules consisting of 25% fibres, 60% polylactic acid, and 15% filler as the final product. The biocomposite granules can be produced at €1073/t and €1013/t with and without mowing costs, respectively. The production cost of the granules is largely influenced by the price of the polymer matrix and the compound composition, while the average market price is approximately €2000/t. Overall, the results indicate that roadside grass fibres may be cost-competitive under the evaluated assumptions. The screening assessment resulted in 364.20–701.32 kg CO₂-eq/t fibre for the flail system and 275.96–327.96 kg CO₂-eq/t fibre for the rotary system, depending on whether mowing was excluded or included. Drying energy and diesel consumption associated with mowing and collection were identified as the main operational emission sources. Full article

Vulnerable coastal urban margins face overlapping pressures from erosion, climate change, and plastic-waste accumulation. This study presents a screening-level numerical assessment of a hollow modular unit made of a recycled polyethylene terephthalate (PET)–concrete composite, proposed for coastal slope protection and stabilisation in Chucuito, Callao, Peru. A limit-equilibrium baseline indicates that the unprotected slope is marginal to unstable under the site’s seismic demand, motivating the evaluation of a surface-protection concept through a parallel, one-way finite element analysis–computational fluid dynamics (FEA–CFD) framework applied at three slope angles (60°, 53°, 45°). The FEA structural-response screening indicates consistent trends across configurations under an equivalent impact load and the adopted basal restraint. For the hydraulic comparison, inlet velocities of 3, 5 and 7 m/s were anchored to the site-specific Delft3D inundation modelling (site maximum 5 m/s), with a conservative 10 m/s upper bound; relative to a rip-rap reference, the hollow configuration suggests midpoint run-up velocity reductions of approximately 52% at θ = 53° under the conservative scenario and ≈57% at 3 and 5 m/s, falling to ≈25% at 7 m/s with overlapping ranges and the simulated free surface exceeding the crest. The CFD free-surface elevations show order-of-magnitude consistency with an indicative EurOtop-based run-up benchmark used as a consistency check rather than as hydraulic validation. Independent of this hydraulic comparison, the hollow geometry saves ≈ 62% of the material volume relative to an equivalent solid concrete block, valorises ≈ 793 post-consumer PET bottles per unit at a 10% dosage, and suggests a 42–58% embodied-CO₂ reduction relative to the same solid-concrete reference, driven mainly by the hollow geometry rather than by the PET substitution itself. The results are internally consistent but not experimentally validated and are intended as a comparative baseline to guide subsequent experimental and field studies, in line with Sustainable Development Goals (SDG) 11, 12 and 13. Full article

The present study was conducted to systematically investigate the effect of adding Polypropylene (PP) fibre at various dosages (0–1.0 kg/m³) on the compressive strength and workability of Blended Portland Cement concrete. All mix variables were kept constant except for fibre content (w/c = 0.45), thereby allowing the dosage effect to be isolated. Standard-sized 150 × 150 × 150 mm cubes were prepared and tested for slump (ASTM C143), fresh density and early-age compressive strength BS 1881-116:1983 at 7 days and 14 days. Slump decreased monotonically from 200 mm to 160 mm as the dosage increased and remained within the EN 206 S4 (High) workability class throughout. Fresh density was essentially unaffected. The early-age compressive strength increased continuously for both test ages, reaching 51.7 MPa at 1.0 kg/m³ at 14 days. One-way analysis of variance confirmed a statistically significant dosage effect at both ages (7-day p < 0.001; 14-day p = 0.003). Based on the strength-workability trade-off, it was found that a pragmatic recommended dosage range is 0.6–0.8 kg/m³, which gives an appreciable strength improvement with a moderate decrease in workability without the need for the addition of extra admixtures. These results offer early age mix design guidance for practitioners and engineers in a wide range of construction applications and can be used to calculate a potential circular economy impact for the mix design: a 100 m³ pour at 0.8 kg/m³ could potentially divert 80 kg of PP waste from landfill or incineration if recycled PP fibres were used instead of the virgin fibres used in the study. Full article

Problem statement: Contaminated mixed plastic waste—bearing metallic, paper, cardboard and organic residues—remains largely excluded from mechanical recycling because conventional routes require a costly, water- and energy-intensive washing–drying pretreatment. Research gap: No published study combines a fully dry, washing-free valorisation route for such waste with certified mechanical characterisation and a quantified CO₂ mass balance that explicitly credits elimination of the washing–drying stage. Methodology: This study presents DMP (Downcycled Mixed Plastic), a patented (OSIM, Romania) dry valorisation process based on continuous single-screw extrusion (D = 150 mm, L/D = 17.3), characterised through differential scanning calorimetry (DSC), certified mechanical/thermal testing at accredited Romanian laboratories, Weber-number dispersion analysis, and a process-parameter sensitivity study. Key findings: The composite exhibits certified mechanical properties (tensile strength 9.22 MPa, elongation at break 112.8%, compressive strength 14.5 MPa); composition–property analysis across four batches shows that increasing the PP weight fraction from 20 to 28 wt% raises tensile strength by 8.3% while reducing elongation by 5.2%; a computed Weber number (We = 166.7 ≫ We_crit) is consistent with fine PP-phase dispersion within the PE matrix; the sensitivity study confirms statistically robust structure–property relationships (R² = 0.93–0.98); and the CO₂ mass balance establishes a net avoidance of 3.150 t CO₂ eq per tonne of waste processed relative to conventional wet recycling. Significance: dry, washing-free processing is a technically promising pathway for valorising plastic waste streams currently considered non-recyclable, potentially reducing production cost by 60–70% relative to wet recycling, pending additional characterisation identified as priorities for future work. Full article

This study presents an environmental and circularity assessment of an integrated insulation-production system that valorises plastic waste and wood packaging waste as secondary material and energy resources. The analysis evaluates the recovery of incoming waste streams and their reintegration into a new production cycle, while the downstream end-of-life of the resulting insulation product remains outside the assessed system boundary. The process chain includes mechanical pre-treatment of wood (grinding, metal separation, and pelletising); thermochemical conversion via wood gasification and gas combustion; and post-combustion CO₂ capture. The captured CO₂ is used in the subsequent polymer processing stages, which comprise mixing, extrusion, thermal treatment, and cooling. Environmental impacts are evaluated through Life Cycle Assessment (LCA), while circularity indicators are assessed within the framework of EN 15804+A2. The results demonstrate the environmental and circularity potential of valorising wood packaging and plastic waste in the context of carbon capture and utilisation (CCU) and sustainable material development. Full article

The plastics industry sector is a massive contributor to greenhouse gas emissions. In this context, it is important to find alternatives to valorise plastic polymer waste, since 63.0% of the plastics produced between 1950 and 2015 were incinerated or disposed of in landfills. This study aims to evaluate the environmental and economic performance of a polymeric control panel for a domestic boiler. The environmental assessment was conducted using the Life Cycle Assessment (LCA) methodology from a cradle-to-grave perspective, allowing the identification of the hotspots of the panel under analysis in two scenarios: virgin panel (VP) and recycled panel (RP). The economic evaluation was performed through a techno-economic analysis (TEA) considering both operating expenditures (OpEx) and annualised capital expenditures (CapEx) allocated to the functional unit. The VP scenario used 100.0% virgin polymer, while the RP scenario used 70.0% virgin polymer and 30.0% internal recycled polymer. The analysis shows a clear synergy: substituting a portion of virgin polymer with recycled PC/ABS reduces both environmental impacts and production costs, while also increasing the sustainability. The results support internal recycling as a practical circularity strategy that can improve environmental performance. The RP scenario is both the environmentally preferable and the economically better option. Additionally, the consistency of results across both LCA and TEA indicates that the identified hotspots represent leverage points for future interventions to amplify benefits to further improve sustainability. For instance, further decarbonization of the Portuguese electricity grid or increased reliance on on-site PV electricity would strengthen the environmental profile of both scenarios. At the same time, continued optimisation of recycling processes could enhance cost savings. Full article

The poultry sector generates large amounts of feather waste every year, providing an abundant keratin-rich residue that is difficult to valorise due to its crosslinked and highly compacted crystalline structure. In the present work, with the aim of promoting its use in biodegradable plastic films, environmentally friendly processes, such as mechanical grinding (compactor grinder, CG), deep eutectic solvents (DES), and steam explosion process (SE) are being explored as alternatives to conventional chemical processes. Thus, biodegradable feather-based films were produced by compounding treated feathers in a torque rheometer at 40 wt.% with glycerol, ethylene glycol, and 1,2-propanediol (propylene glycol), followed by hot pressing. All formulations produced homogeneous and translucent films, which were characterized in terms of colorimetric properties and thermal and mechanical behaviour, as well as their degradation in soil conditions, revealing pronounced differences in properties as a function of the specific combination of feather treatment and plasticizer employed. Interestingly, soil disintegration tests revealed the fastest degradation of films of DES-treated feathers plasticized with glycerol. Overall, controlling feather treatment and plasticizer type enables tuning of mechanical performance and biodegradation, supporting keratin-based films as a viable route for feather waste valorisation. Full article

The conversion of plastic waste into hydrogen offers a promising waste-to-value pathway, but its industrial viability is constrained by high external energy demand associated with thermochemical processing. This study evaluates the energy performance of hydrogen production from mixed plastic waste via pyrolysis and in-line steam reforming, with a focus on reducing utility consumption through systematic heat integration. A steady-state process model was developed in Aspen Plus for a representative mixture of polyethylene, polypropylene, and polystyrene, followed by detailed energy analysis and pinch-based heat integration using Aspen Energy Analyser. Baseline utility requirements were quantified and compared against optimised configurations incorporating targeted heat exchanger network modifications. The base-case analysis identified significant recoverable heat, enabling a reduction in total external utilities from 7.14 to 2.88 GJ h⁻¹, corresponding to a 59.6% decrease in utility demand. Sequential heat integration scenarios further reduced heating and cooling duties while maintaining process operability, demonstrating the effectiveness of iterative, pinch-guided design. The results show that high-temperature waste-plastic-to-hydrogen systems need not be utility-dominated when energy integration is embedded at the design stage. These findings highlight heat integration as a critical enabler for improving the energy efficiency and sustainability of pyrolysis–reforming routes and provide a robust framework for developing scalable, low-carbon hydrogen production from plastic waste. Full article

This study investigates the valorisation of lemon industry by-products as carbon sources to produce poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) using the halophilic archaeon Haloferax mediterranei. The resulting polymer (HFX PHBV) was supplemented with nucleating agents (orotic acid, boron nitride, and theobromine) and compared with a commercial PHBV grade (Enmat Y1000) under identical conditions. Fermentation strategies were optimised by varying the lemon by-product concentration, inoculum size, and nutrient stoichiometry (C:N:P ratios), followed by scaleup in a 2 L bioreactor. A 11% (v/v) lemon by-product combined with a 5% (v/v) inoculum yielded the highest productivity under minimal medium conditions (2.127 g/L PHBV), while enriched media further enhanced the polymer accumulation (up to 3.250 g/L PHBV). A comparative characterisation of HFX PHBV and Enmat Y1000, using NMR, TGA, MFR, DSC, Raman spectroscopy, XRD, and DMA, revealed that HFX PHBV exhibited lower crystallinity, increased flexibility, and a high hydroxyvalerate content (27.4%), which conferred improved ductility. Investigation of nucleating agents demonstrated that orotic acid was the most effective at enhancing the crystallisation kinetics. Overall, this study demonstrates an efficient PHBV production process based on waste valorisation, yielding a biopolymer with competitive physicochemical properties relative to a commercial standard, and provides integrated solutions to the global challenges of plastic pollution and food waste. Full article

The valorisation of agro-industrial residues in polymer composites represents a promising strategy for waste valorisation and the development of sustainable packaging materials. In this study, coffee silverskin (CSS), a lignocellulosic by-product, was added at concentrations up to 15 wt.% and processed into sheets via extrusion, followed by thermoforming using moulds with different draw ratios. Processability (MFI) and structural (FTIR), morphological (SEM, optical microscopy), thermal (TGA, DSC), and mechanical characterizations (tensile tests) were performed. Although the SEM images showed that CSS particles were well dispersed in the polymer matrix, and the mechanical behaviour was negatively affected when compared to the neat biopolymer. On the other hand, the addition of CSS increased the melt flow index, suggesting a lubricating/plasticizing effect. DSC results showed a reduction in cold crystallization temperature with CSS addition, confirming a nucleating effect, while glass transition and melting temperatures remained unchanged. Despite a narrower thermoforming temperature window with increasing CSS content, defect-free parts with adequate mould replication were successfully obtained for all formulations. Overall, the incorporation of CSS into PLA matrix provides a viable pathway for producing thermoformable as potential compostable composites, enabling waste valorisation within a circular bioeconomy framework. Full article

This paper investigates the design potential of post-consumer plastic waste through the Waste Driven Design (WDD) method, developed at IUAV University of Venice and implemented in both experimental and semi-industrial contexts. WDD proposes a situated and transdisciplinary approach, where waste is no longer regarded as a material to be discarded, but as a resource to be explored, transformed, and valorised. Using the Marble CAP case study—a new material derived from non-recyclable food packaging—the paper presents an iterative and scalable design process that combines technical experimentation, material storytelling, and application potential. The stages of the process are examined, from waste collection and cataloguing to the production of pressed sheets, which are tested under various conditions and finishes. The results demonstrate how, in design, material can become a catalyst for new aesthetics, languages, and production chains. Rather than concluding with the formal outcome, the project opens up spaces for critical and operational interventions along the supply chain, highlighting how design can contribute to imagining and activating alternative trajectories for waste transformation. Full article

The management of solid waste and the supply of energy are two of the most important environmental problems of our time. Projections indicate that by 2050, the global demand for electrical energy is expected to increase by 35% and the amount of solid waste generated to increase by 45%. In this context, polymeric waste materials such as biomass and plastics can be valorised through thermochemical processes for the generation of energy. Gasification, which converts carbonaceous materials into syngas, tar, and char, is one of the most promising recycling technologies. The composition and relative quantities of the products are influenced by the process configuration, operating parameters, and the type of fuel used. Tar removal is facilitated by adding specific catalysts to the process. The co-processing of biomass and plastics in the gasification process, called co-gasification, improves the gas yield and reduces solid residues. This review evaluates catalytic and non-catalytic co-gasification of biomass waste and non-biodegradable plastics, with a focus on syngas production and its energy potential. Full article

As the generation of Municipal Solid Waste (MSW) has exponentially increased, this poses a challenge for waste managers, such as municipalities, to effectively control waste streams. If waste streams are not managed correctly, they negatively contribute to climate change, marine plastic pollution and human health effects. Therefore, waste streams need to be identified, categorised and valorised to ensure that the most effective waste management strategy is employed. Research suggests that a more efficient process of identifying and categorising waste at the source can achieve this. Therefore, the aim of the paper is to identify the state of research of AI-powered drones in identifying and categorising waste. This paper will conduct a systematic review and meta-analysis on the application of drone technology integrated with image sensing technology and deep learning methods for waste management. Different systems are explored, and a quantitative meta-analysis of their performance metrics (such as the F1 score) is conducted to determine the best integration of technology. Therefore, the research proposes designing and developing a hybrid deep learning model with integrated architecture (YOLO-Transformer model) that can capture Multispectral imagery data from drones for waste stream identification, categorisation and potential valorisation for waste managers in small-scale environments. Full article