Search Results (2,517)

The increasing demand for sustainable materials is driving research into the valorization of agro-industrial waste as lignocellulosic alternatives in engineered wood product manufacturing. This study investigates the use of bitter orange (Citrus aurantium L.) peel as a bio-based filler in particleboards bonded with a bio-based tannin/hexamine adhesive. Panels were fabricated by partially substituting wood chips with orange peel powder at five levels (0, 2.5, 5, 10, and 15 wt%), hot-pressed at 180 °C for 8 min at a constant biomass-to-adhesive ratio of 9:1 (w/w). Firstly, the effect of temperature on orange peels and then the microscopic structure of the composite was observed through optical stereomicroscopy and SEM. Then, mechanical performance, water resistance, and thermal conductivity were also analyzed. Substitution of up to 10 wt% of wood chips with orange peel allowed for the maintenance of internal bond strength, modulus of rupture, and modulus of elasticity, while the 2.5 wt% formulation yielded a statistically significant improvement in axial thermal insulation. Conversely, when the amount of orange waste rises over 10 wt%, significant decreases in internal bond and modulus of rupture were recorded. These findings demonstrate that C. aurantium peels can be used as a viable filler for formaldehyde-free particleboards, offering a promising strategy for orange waste valorization in the wood panel industry. Full article

The growing demand for safe and minimally processed fresh fruits and vegetables has highlighted the need for effective and environmentally friendly decontamination methods. Conventional washing techniques often fail to remove pesticide residues and microbial contaminants efficiently, while chemical disinfectants raise concerns related to toxicity and sustainability. In this context, natural surfactants and fermentation-derived solutions have emerged as promising alternatives. This critical review presents aspects regarding recent advances in the use of plant-based and microbial surfactants, for the decontamination of fresh products, with highlights on their mechanisms of action, ranging from enhanced removal of hydrophobic residues to disruption of microbial bio-films. Also, particular attention is given to the potential of combining surfactants with bioactive compounds obtained through fermentation processes, as well as to the valorization of agro-industrial waste as sustainable raw materials. The impact of these treatments will contribute to the improvement of product quality, safety, and environmental compatibility. Finally, current challenges related to scalability, standardization, and regulatory aspects are outlined, highlighting the need for further research to support the transition from laboratory studies to real-world applications. Full article

In response to the increasing needs for environmentally friendly products, lignocellulosic natural fibers have been of interest as potential replacements for synthetic reinforcement materials in textiles, composites, and related applications. Among these resources, bast fibers derived from plant stems (flax, hemp, nettle, jute, hop), which contain a high cellulose content, have good mechanical properties, low density, and are renewable, are highly promising. Steam explosion has emerged as a green fiber extraction, defibrillation, and surface modification pretreatment technology. Despite the growing number of studies on steam-exploded natural fibers, a comprehensive understanding of the relationships between processing conditions, fiber modifications, mechanisms, and end-use performance remains limited. This review investigates the structural, chemical, and morphological influences of steam explosion on bast fibers. Specifically, it focuses on the mechanism of steam explosion including the solubilization of hemicellulose, partial lignin redistribution or removal, fiber individualization, and cellulose enrichment. The literature indicates that steam explosion can improve fiber separation, fineness, surface morphology, and interfacial adhesion of the composite materials and reduce the use of hazardous chemicals compared with conventional extraction methods. Nonetheless, conflicting results have also been documented, where the same steam explosion conditions can yield distinct fiber characteristics according to biomass type, composition of biomass, moisture concentration, and the amount of processing involved. Excessive treatment severity may lead to fiber shortening, cellulose degradation, and deterioration of fiber quality, particularly for textile applications requiring long fibers. This review highlights current knowledge gaps regarding the optimization of processing conditions, the understanding of steam explosion mechanisms, and the scale-up of the technology for industrial applications. Full article

This study investigates citrus peel powder (CP) as an environmentally friendly admixture to regulate plant-derived urease (with soybean powder (SP) as the urease source) and to promote bio-mediated CaCO₃ mineralization, thereby improving the mechanical and freeze–thaw (FT) resistance properties of cement-based materials. When CP is combined with urea and soybean urease, it exhibits a regulatory effect on urease activity. For the CPUD (CP-encapsulated urea combined with soy powder)-modified material with SP dosage in cement content of 0.2 wt%, the CP–urea modification treatment can effectively improve their mechanical properties and FT durability. The flexural and compressive strengths at 28 days are increased by 10.53% and 11.19%, respectively, compared to the blank group. After freeze–thaw cycles, the strengths are still 27.08% and 26.67% higher than those of the blank group, and their respective strength loss rates are 7.58% and −5.77% (negative indicating a net strength increase), compared with 21.31% and 9.48% for the blank group. X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy analyses reveal that CP–urea promotes the formation and effective packing of calcium carbonate. Mechanistically, CP establishes a stable hydrogen-bonding network with both urea and urease, exerting a dual regulatory effect: it enhances the electrophilicity of urea while also creating a physical mass transfer barrier to precisely control biomineralization. Notably, CP can be directly used without pretreatment, offering a sustainable strategy for citrus peel waste valorization. Full article

The role of internal combustion engines in future transport systems is expected to remain central, particularly in hard-to-abate sectors such as heavy-duty road transport and maritime applications. However, their decarbonization requires the adoption of low-carbon and renewable fuels. This review examines hydrogen, methane-based fuels, methanol, and ethanol for internal combustion engine applications using a pathway-based approach that integrates life-cycle assessment, technology readiness level, commercial readiness level, and engine-related considerations. The reviewed literature shows that the environmental performance of these fuels varies strongly depending on feedstock, production pathway, process configuration, and energy source. From a Well-to-Tank perspective, hydrogen pathways exhibit particularly large variability, ranging from around 3 gCO${}_2$eq/MJ for wind-based electrolysis to around 230 g CO${}_2$eq/MJ for coal gasification. Methane-based fuels range from around 16 gCO${}_2$eq/MJ for fossil compressed and liquefied natural gas to negative values for waste- and manure-based biomethane. Methanol and ethanol also show substantial variability, with renewable, waste-derived, and bio-based pathways generally offering substantially lower life-cycle greenhouse gas (GHG) emissions than fossil-based routes. In the use phase, Tank-to-Wheel analysis shows that energy demand remains relatively similar across fuels, while differences in direct emissions are mainly related to fuel carbon content and other GHG species such as ${\mathrm{CH}}_4$ or ${\mathrm{H}}_2$ slip and combustion-related species such as ${\mathrm{N}}_2\mathrm{O}$. The Well-to-Wheel comparison for heavy-duty applications highlights that upstream fuel production pathways strongly influence overall performance, while use-phase contributions play a secondary role and mainly affect the final ranking when upstream emissions are comparable. Overall, the review shows that pathway selection is more influential than fuel identity itself, highlighting that effective decarbonization strategies should focus on pathway design and upstream fuel production rather than on fuel categories alone, and that renewable and bio-based pathways offer the greatest potential for achieving very low or near-zero life-cycle GHG emissions in internal combustion engine applications. Full article

Marine biowaste (fish and crustacean processing residues) is produced in tens of millions of tons annually, yet remains dramatically underutilized as a feedstock. Hydrothermal carbonization offers a technically attractive valorization route for these high-moisture, non-lignocellulosic materials, converting them to carbon-enriched hydrochar without the energy-intensive pre-drying required by pyrolysis. This focused review treats marine animal waste as the primary studies and micro- and macroalgal hydrothermal carbonization as a comparative benchmark to understand how the current research is going, the impact of production parameters, potential application, and possible research gaps to explore. Crustacean waste yields substantially more hydrochar (37–69%) than fish waste (15–34%) under equivalent conditions, driven by calcium carbonate retention in the solid phase. Unactivated hydrochars have low BET surface areas (<30 m²/g) and modest adsorption capacities (~10 mg/g). Acid deashing followed by KOH activation at 700 °C unlocks nanoporous structures with BET surface areas up to 680 m²/g and oxytetracycline adsorption capacities of 61.3 mg/g. Critical research gaps include the absence of techno-economic analysis, limited life-cycle assessment, and non-standardized reporting conventions. These must be addressed before upscaling to industrial viability can be achieved. Full article

Hexavalent chromium (Cr (VI)) contamination of water resources constitutes a major environmental and public health issue due to its high toxicity, mobility, and carcinogenic properties. This review examines recent advances in Cr (VI) removal technologies from water and wastewater, with emphasis on membrane-based separation processes and adsorption approaches. Conventional treatment methods, including chemical precipitation, ion exchange (IX), electrocoagulation (EC), electrodeionization (EDΙ), bioremediation, and photocatalysis, are comparatively discussed in terms of removal efficiency, operational limitations, and applicability. In parallel, sustainable adsorbent materials derived from biomass and agricultural waste are evaluated as environmentally friendly and cost-effective alternatives for chromium removal. The role of functional groups, adsorption mechanisms, and redox interactions involved in Cr (VI) reduction and immobilization is also analyzed. Attention is given to membrane technologies, such as reverse osmosis (RO), nanofiltration (NF), electrodialysis (ED), and ultrafiltration (UF) after surface modification with the incorporation of nanomaterials and/or the application of Layer-by-Layer (LBL) assembly techniques, which enhance selectivity, permeability, and antifouling behavior. The reviewed studies demonstrate that advanced membrane systems and bio-based adsorbents can achieve high chromium removal efficiencies while supporting sustainable water treatment practices. Overall, the combination of membrane technologies with functionalized materials represents a promising direction for the development of efficient and environmentally sustainable Cr (VI) remediation systems capable of meeting increasingly strict regulatory limits. Full article

The growing demand for sustainable construction materials has stimulated interest in alternative binders derived from waste resources. This study investigates the use of calcined crab shell (CCS), a calcium-rich marine biowaste, as a partial replacement for Portland limestone cement. Cement pastes containing 0%, 5%, 10%, and 15% CCS were prepared and evaluated through compressive strength, water absorption, open porosity, bulk density, SEM, XRD, FTIR, and TGA analyses. The results showed that incorporating 10% CCS produced the most favorable performance, increasing compressive strength from 17.6 MPa to 33.6 MPa after 28 days of curing. This improvement was accompanied by reduced porosity, increased bulk density, and the development of a denser and more homogeneous microstructure. Physicochemical analyses suggest that CCS acts both as a filler and as a source of reactive calcium species. The CaO generated during calcination may participate in hydration processes and influence the formation of hydration products, contributing to matrix densification. In contrast, the incorporation of 15% CCS resulted in increased porosity, a less homogeneous microstructure, and lower mechanical performance. These findings indicate that replacing Portland limestone cement with up to 10% CCS can improve the properties of cement pastes while promoting the valorization of marine shell waste and reducing cement consumption, thereby supporting the development of more sustainable construction materials. Full article

Summer overheating is an escalating challenge for lightweight timber constructions, which inherently lack the thermal mass of traditional masonry. This study investigates the thermo-physical properties of a mycelium-based biocomposite (MBB) insulation produced from industrial wood waste, with particular focus on volumetric heat capacity (C_v). The C_v and thermal conductivity (λ) of MBB were experimentally measured and benchmarked against seven reference insulation materials spanning bio-based, mineral, and petroleum-derived categories, with results visualized on an Ashby diagram. The areal heat capacity (κ) of nine representative wall assemblies was theoretically calculated per EN ISO 13786. Even though the MBB achieved the highest thermal conductivity (λ = 0.0641 ± 0.0024 W·m⁻¹·K⁻¹) among the tested insulation materials, it offers 4.7 times higher C_v than EPS. Analytical modeling indicates a thermal phase shift of 8.2 h for a 185 mm layer, compared to 4.6 h for EPS. The softwood timber + MBB wall assembly achieved an areal heat capacity approaching the lower boundary of traditional masonry performance. These findings demonstrate MBB’s potential as a bio-based, waste-derived insulation for significantly enhancing the thermal inertia of lightweight timber buildings and mitigating summer overheating risk. Full article

Advancing urban sustainability transitions through effective environmental policies requires understanding how residents perceive and respond to policies. While perceived policy effectiveness (PPE) has been studied in waste management and recycling programs, its role in shaping demand for bio-based materials remains underexplored. This study investigates whether and how PPE is associated with bamboo product consumption among 1121 urban residents in Zhejiang Province, China. Drawing on an extended Theory of Planned Behavior (TPB) framework, we use ordinary least squares estimators to examine the direct and interactive associations between PPE and actual bamboo consumption behavior. Results show that PPE is significantly and positively associated with bamboo product consumption. Interaction analysis reveals heterogeneous effects: PPE shows a weak positive interaction with environmental knowledge, but a negative interaction with environmental values. This suggests that policy signals may complement cognitive preparedness while partly compensating for low value-based motivation. A supplementary analysis indicates that this conditioning extends to economic resources, with the association concentrated among lower-income, more price-sensitive consumers. This study extends PPE research from post-consumption management to the purchasing stage of sustainable products. It highlights the role of policy perceptions in shaping demand-side adoption of lower-impact materials, with implications for urban sustainability transitions and city-level policies promoting bio-based alternatives. Full article

The growing use of reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA) is an important practice to achieve more sustainable pavements, as it reduces the consumption and environmental impact of virgin materials. However, aging induces binder stiffening that requires effective rejuvenation to restore overall performance. This study provides a comprehensive comparative analysis of ten chemically different waste oils—waste engine oil (WEO), waste cooking oil (WCO), yellow grease (YG), waste hydraulic oil (WHO) waste electric transformer oil (WETO), slop oil (SO), sludge-derived bio-oil (SDBO), tire pyrolysis oil (TPO), plastic pyrolysis oil (PPO), and algal residue oil (ARO)—as recycled HMA mixture rejuvenators, linking oil composition to binder regeneration and mixture performance. Binder properties were determined by rotational viscosity (RV), dynamic shear rheometer (DSR) and bending beam rheometer (BBR), whereas mixture performance was assessed in terms of Superpave mechanical properties, Hamburg wheel-tracking test (HWTT) for rutting resistance and mixture BBR for low-temperature cracking resistance. Performance grade (PG) evaluations showed that WETO and WEO restored the 50% and 75% RAP binders, respectively, to a grade close to PG 64-16 at the lowest dosages. The Superpave volumetric properties of all restored mixtures were similar to those of the control mixture, denoting corrected mixture balance and compaction level. HWTT results indicated that WETO-recycled mixtures revealed the lowest rut depth at 50% RAP, while WEO-recycled mixtures exhibited the lowest rut depth at 75% RAP after 20000 passes. Additional evidence supporting these results can be found in BBR mixture data, which demonstrated that WETO at 50% RAP and WEO/WETO at 75% RAP showed the most reduction in creep stiffness and improvement in creep rate. The correlation, regression, and PI analyses were in good agreement with the experimental results, where WETO and WEO exhibited the best overall performance at 50% and 75% RAP, respectively. In summary, these results indicate that the performance of waste oil rejuvenator in recycled HMA mixtures is highly dependent on RAP content and point to WETO and WEO as feasible, environmentally friendly options for high-RAP recycled HMA. Full article

In protracted humanitarian crises, solid waste management (SWM) becomes a major challenge due to limited resources, inadequate infrastructure, and competing response priorities. Waste generated in humanitarian settings typically consist of heterogeneous streams, where plastics, biodegradable fractions, and packaging materials represent the dominant components. Proper management of this waste is essential to reduce health risks and environmental impacts on local communities. Within this framework, sustainable bio-based alternatives and compostable solutions represent promising alternatives. The EU-funded Bio4HUMAN project promotes the integration of innovative bio-based solutions aligned with humanitarian and sustainability goals. An exploratory assessment focused on analyzing waste production, material composition, and handling practices in two case study locations in Sub-Saharan Africa (Democratic Republic of Congo (DRC) and South Sudan (SS)). The results indicate that humanitarian waste cannot be clearly distinguished from household or commercial waste, as streams are typically mixed. Waste composition is dominated by organic matter (43–65%), followed by plastics (15–33%), while other fractions such as paper, glass, metals, and textiles are less significant. Further insights into challenges and opportunities were obtained through a combination of quantitative surveys (n = 29), qualitative interviews with key informants (KIIs) (44) and group discussions sessions (FDG) (9), direct observations, and literature review. Subsequently, a scoping approach was applied to map and classify suitable sustainable solutions into two main categories: bio-based products (BBPs) and organic waste valorization technologies. These were assessed through life cycle assessment (LCA) in accordance with ISO 14040 and 14044, applying SimaPro v.10.2.0.3 software and the Ecoinvent 3.10 database, and compared against fossil-based alternatives. This study compares two case scenarios: a HDPE oil bottle versus PLA alternative (functional unit 6 L), and PE water container versus PLA alternative (functional unit 10 L). For the oil bottle, PLA shows a lower carbon footprint (1.33 kg CO₂-eq) than HDPE (2.37 kg CO₂-eq). In contrast, for the water container, PLA performs worse (2.22 kg CO₂-eq) compared to PE (1.59 kg CO₂-eq), due to higher material demand. The results suggest that benefits are context-dependent and most evident for lightweight products with high leakage risks, particularly when composting infrastructure is accessible. This study advances previous work on humanitarian SWM by integrating field-based waste flow characterization with context-specific screening and life cycle assessment of bio-based alternatives, providing quantitative evidence on the conditions under which these solutions can effectively reduce environmental burdens in protracted crisis settings. Full article

The physicochemical characteristics of hydrochars produced from tobacco stems through hydrothermal carbonization (HTC) at different temperatures were investigated, along with the variation in contents of nicotine, niacin, and chlorogenic acid in both the hydrochars and the liquid phase. The results indicated that dehydration was the predominant reaction during HTC of wet tobacco stems (WTS), leading to a decrease in the H/C and O/C atomic ratios of the hydrochars. As temperature increased, polycondensation and aromatization reactions became more pronounced, which corresponded with a reduction in the intensity of functional group vibrations such as C–N and N–O in FT-IR spectra. XPS analysis revealed a gradual increase in C=O content, whereas the proportions of C–OH and C–O bonds declined from 51.74% and 35.13% to 36.95% and 20.84%, respectively. Furthermore, the content of pyridine-N rose from 31.08% to 41.30%, while pyrrole-N and quaternary-N contents decreased to varying degrees. Both nicotine and niacin levels in the hydrochars and carbonization liquids exhibited an initial increase followed by a decline, whereas chlorogenic acid content consistently decreased. The underlying mechanisms for the observed changes in nicotine, niacin, and chlorogenic acid contents during HTC are discussed in detail. Full article

Vermicomposting is an eco-friendly biotechnology for organic waste valorization. As the primary product of earthworm biotransformation, vermicompost is a high-value bio-organic fertilizer abundant in diverse biologically active components. To date, most studies have focused on quality variation during the earthworm transformation process, while research on quality variations in the resulting vermicompost fertilizer during long-term storage remains scarce. To explore the shelf-life of vermicompost fertilizer and its key influencing indicators, this study investigated the changes in quality indicators in sealed-packaged vermicompost over a 180-day period using two typical vermicompost, namely cattle manure vermicompost (CM) and straw-amended cattle manure vermicompost (CMS). The temporal dynamics of physicochemical properties, nutrient contents, humification indices, enzyme activities, and microbial communities were monitored. The vermicompost quality was evaluated, and core quality drivers were identified using an integrated principal component analysis-partial least squares (PCA-PLS) approach. The results indicated that moisture content (MC), total organic carbon (TOC), and total nitrogen (TN) declined progressively, whereas available phosphorus (AP) and available potassium (AK) peaked at day 150 and day 120, respectively, and the humification rate (HR) increased by 2.6–4.0-fold. Bacterial diversity and relative abundance slightly decreased, accompanied by taxonomic differentiation, whereas fungal communities maintained stable diversity. Most enzyme activities, including urease, phosphatase, catalase, and dehydrogenase, reached their maxima at day 120. Comprehensive quality scores peaked at day 150, with a marked decline observed by day 180. The recommended shelf-life of vermicompost fertilizer is 150 days. The key quality determinants include TN, electrical conductivity (EC), pH, actinomycete abundance, TOC, TP, bacterial abundance, AP, AK, and HR. These findings provide theoretical support and references for the storage management and quality control of commercial vermicompost products in practice. Full article

Turning waste materials into renewed value is a central aspect of any future circular (bio)economy. Urine and ash are two prominent waste materials produced globally and in considerable amounts each year. Both contain several interesting substances that are so far de facto lost or may even pose a threat to the environment. Urine from industrial-scale farming, for instance, is responsible for significant pollution of soil and groundwater with nitrogen and phosphorous, yet N and P are also high-demand substances in agriculture and industry. Similarly, ash is rich in several interesting metal ions, but is still usually disposed of in a landfill. Using a sequence of simple yet effective biological and chemical processes, it may be possible to convert these two unwanted materials into “green” ammonia and calcium phosphate, both valuable high-demand substances with numerous applications, and with few potentially valuable leftovers still to be dealt with. Eventually, and after considering some of the logistics of the process, such as the collection of materials, this “urinash process” may be upscaled to effectively reduce waste by turning it into renewed value, thus also substituting for—some of—both the energy-intensive synthesis of grey ammonia and the destructive mining for phosphate salts. Full article