Search Results (1,208)

Poultry feather waste, one of the major by-products of the poultry industry, represents an underutilized protein-rich biomass with significant potential for sustainable valorization within the circular bioeconomy. This narrative review examines recent advances in the use of poultry feathers as a renewable source of keratin for the development of keratin-based biomaterials. A structured literature search of original research articles published between 2015 and 2026 resulted in a final primary evidence map of 524 records, which was used to evaluate current knowledge on poultry feather management, keratin structure and properties, extraction technologies, and the development of feather-derived biomaterials. The reviewed literature indicates that keratin recovery can convert feather waste into higher-value materials, although its environmental performance depends on the extraction route, energy and chemical requirements, and comparison with established feather-management pathways. Recent advances highlight the potential of feather-derived keratin for biodegradable films, composites, hydrogels, coatings, packaging, biomedical, agricultural, and environmental applications. However, challenges remain regarding scalable extraction technologies, material performance, process standardization, and industrial implementation. This review provides a comprehensive overview of current research and identifies future directions for integrating poultry feather valorization into circular bioeconomy strategies, supporting resource efficiency and the development of sustainable bio-based materials. Full article

The building and construction sector accounts for approximately 37% of global CO₂ emissions and nearly 50% of material extraction, driving urgent demand for sustainable material alternatives. Bio-based composites derived from recycled waste and biomass offer a promising pathway toward a circular built environment, yet their production remains hampered by biomass batch variability, the absence of standardized process protocols, and sensitivity to environmental conditions. Digital twin (DT) technology, with its capacity for real-time monitoring, predictive simulation, and closed-loop optimization, has been widely applied in building operation and maintenance but has received scant attention at the material production end. This paper addresses this cross-disciplinary gap by proposing a five-layer DT conceptual framework for the standardized production of bio-based composites, developed using the Design Science Research paradigm. The framework comprises a physical layer, a data acquisition layer, a virtual model layer, a decision and control layer, and a lifecycle-circularity layer, mapped onto five production stages from raw material to recovery. An observe–simulate–decide–adjust (OSDA) closed-loop mechanism runs across all stages. A synthetic-data simulation of the OSDA closed-loop mechanism across 200 virtual production batches illustrates a 48.5% reduction in performance variability (95% CI: 42.9–53.7%) and a 99.0% reduction in the reject rate (95% CI: 96.9–100.0%) in a biochar–recycled-HDPE panel scenario; sensitivity analysis confirms robustness across a range of moisture penalty assumptions. These results are derived from a simplified regression model and constitute numerical proof-of-concept rather than empirical validation. The study contributes a structured, standards-aligned architecture that bridges digital twins and circular building materials, providing a methodological reference and conceptual justification for industry stakeholders. Full article

Large-scale and recurrent Sargassum beaching events along the coastlines of Brazil, Mexico, and the Caribbean pose significant environmental, social, and economic challenges due to biomass accumulation and decomposition. Meanwhile, valorization of underutilized waste streams into composite materials can advance circular economy strategies. Building upon previous findings on Sargassum-based particleboards, this study investigated increased pressing temperature and residual high-density polyethylene (HDPE) incorporation as strategies to improve dimensional stability. Medium-density particleboards were manufactured from Sargassum biomass and sugarcane bagasse, with and without residual HDPE, using bio-based castor oil polyurethane resin. The panels were characterized regarding physical, mechanical, and thermal properties to assess their suitability for non-structural applications. HDPE-containing formulations showed reduced 24 h thickness swelling from 21% to 15%, while exhibiting an overall reduction in mechanical performance, particularly in bending and internal bond strength properties. Despite this trade-off, the developed particleboards demonstrated potential for furniture and indoor building applications while simultaneously valorizing marine, agro-industrial, and plastic residues. These findings support Sargassum biomass as a sustainable feedstock for particleboard production and indicate that residual HDPE can improve 24 h thickness swelling performance, contributing to circular economy strategies and low-impact material development for applications across the built environment sector. Full article

The global tea industry generates millions of tons of waste annually, yet the bacteria capable of degrading this recalcitrant biomass remain poorly characterized. This study performed whole-genome sequencing and comparative genomic analysis of six bacterial strains isolated from oolong tea residue fermentation: Bacillus sp., Paenibacillus sp., Pantoea sp., two Pseudomonas isolates, and Stenotrophomonas sp. Genome sizes ranged from 3.61 to 6.33 Mbp, with GC content from 43.2% to 66.5%. Average nucleotide identity (ANI) analysis confirmed species-level identification for Paenibacillus (ANI > 95%), Pantoea (ANI > 95%), and both Pseudomonas isolates (ANI > 95%), while the Bacillus and Stenotrophomonas isolates showed ANI < 95% to all reference genomes, suggesting potential taxonomic novelty requiring further characterization. Antimicrobial resistance genes were detected only in Bacillus (cat86, dfrG) and Pantoea (oqxB). Genome-wide MGE profiling identified 349 MGE-associated genes across all six strains, including 101 IS elements, 61 integron-associated genes, and 183 plasmid-associated genes; tetracycline resistance-associated gene homologs were additionally detected in four strains below CARD thresholds. Virulence-associated gene profiling revealed that the 32 factors identified in Pseudomonas isolates primarily encode motility, biofilm formation, and secretion system components, traits associated with environmental adaptation rather than pathogenicity. Carbohydrate-active enzyme (CAZyme) annotation identified conserved plant biomass-degrading capabilities across all isolates. Descriptive comparisons suggested potential differences in enzyme profiles relative to isolation time: early-stage isolates appeared to harbor more hemicellulose-degrading enzymes, while late-stage isolates showed more lignin- and polyphenol-related enzyme annotations; however, these patterns require experimental validation. This genomic resource provides a foundation for understanding bacterial adaptation to tea waste environments and informs candidate strain selection for future inoculant development studies. Full article

The rapid expansion of aquaculture has led to a substantial increase in the generation of organic waste, nutrient-rich effluents, and residual biomass, creating significant environmental challenges while simultaneously providing opportunities for resource recovery within the circular bioeconomy. Environmental biotechnology offers a broad range of solutions for transforming these waste streams into valuable products, including renewable energy, fertilisers, biochar, microbial biomass, and other bio-based resources. However, the practical implementation of these technologies in floating aquaculture systems remains fragmented due to the lack of integrated engineering approaches. This review critically analyses the current state-of-the-art in environmental biotechnology pathways for aquaculture waste valorisation, covering biological, physicochemical, and thermochemical technologies applicable to floating production systems. The assessment covers anaerobic digestion, composting, insect bioconversion, microalgae cultivation, integrated multi-trophic aquaculture, nutrient recovery, hydrothermal carbonisation, and pyrolysis, together with their technological maturity, offshore applicability, and contribution to circular resource recovery. Beyond reviewing existing technologies, this paper proposes the “Circular Floating Aquaculture Systems Engineering Integration Framework” (CFAS-EIF), a systems engineering concept that integrates floating production infrastructure, waste collection, resource recovery technologies, digital management, and circular value chains into a unified architecture. The framework illustrates how environmental biotechnology can be implemented through coordinated engineering integration, enabling the transition from waste management to resource valorisation in offshore aquaculture. The proposed framework provides researchers, engineers, and industry stakeholders with a comprehensive reference for designing next-generation aquaculture platforms that support sustainable resource management, climate change mitigation, and a circular bioeconomy. Full article

This study explores the development of sustainable composite materials based on phosphogypsum (PG), an abundant industrial by-product, reinforced with olive and eucalyptus wood chips. The objective is to valorize waste streams while enhancing the mechanical, thermal, and acoustic performance of the base material for eco-efficient construction applications. Composites were prepared with fiber contents of 5%, 10%, 15%, and 20% and evaluated through standardized experimental tests. Mechanical behavior was assessed via three-point bending tests, revealing a 26% improvement in flexural strength at 15% eucalyptus content. Water absorption increased with fiber content but remained lower in eucalyptus-reinforced composites due to better fiber–matrix cohesion. Thermal conductivity decreased significantly from 5% to 20% fiber content, reaching 0.60 W/m·K at 20% eucalyptus content, indicating enhanced insulation potential. Acoustic tests, performed using an impedance tube in accordance with ISO 10534-2, showed strong frequency-dependent absorption. The 20% olive composite achieved a peak absorption coefficient of 0.78 and an NRC of 0.68, demonstrating excellent sound-damping characteristics. This work introduces a novel integration of two underutilized Mediterranean biomasses into PG matrices and highlights their multifunctional benefits. The resulting composites offer a low-cost, low-carbon solution for thermally and acoustically optimized building components, advancing circular economy principles in the construction sector. Full article

The global interest in utilizing waste from agro–industrial processes through the implementation of clean technologies is rapidly increasing. This study evaluates the technical, economic, and environmental feasibility of valorizing regional agro–industrial residues in Santander, Colombia, specifically coffee mucilage, cocoa mucilage, and pig manure, using integrated biorefinery scenarios. Modernizing these processes is essential given a theoretical energy potential of 75,000 TJ/year, which could generate up to 20,833 GWh/year. Three biorefinery scenarios were designed and simulated using Aspen Plus^® to produce bio-hydrogen, methane, and methanol. The total plant capacity was established at 31.7 t/day, distributed according to regional biomass availability: 4.62 t/day of cocoa mucilage, 1.83 t/day of coffee mucilage, and 25.25 t/day of pig manure. The technical results for Scenario 1 indicated a reformed H₂ production of 0.15 t/day with an associated preheating energy requirement of 193,365 kJ/h. Environmental impact assessment using the ReCiPe 2015 Midpoint methodology identified Scenario 3 as having the lowest direct CO₂ mass flow (9.28 t/day) due to carbon consumption during methanol synthesis. However, Scenario 1 reported a CO₂ equivalent (CO₂e) of 194.37 t/day, reflecting indirect emissions from thermal and energy requirements. Economic analysis, validated through engineering cost references, demonstrated that while Scenario 3 offers a diverse product portfolio, it is currently not cost-effective as the production costs exceed the total expected income. Consequently, Scenario 2 is identified as the most balanced alternative for the Santander context, offering a sustainable compromise between technical efficiency, environmental mitigation, and economic viability. Full article

The application of exogenous nutrient bags (ENBs) is critical for achieving high yields in morel mushroom cultivation; however, the high cost and lack of locally adapted formulations have become major constraints for the sustainable expansion of this industry. This study aimed to evaluate the effects of ten treatments, including a conventional formulation control, incorporating locally available agricultural by-products (rapeseed straw, organic fertilizer, alfalfa, and oats), on soil fertility, enzyme activity, microbial community structure, and ultimately the yield and quality of cultivated Morchella sextelata in Jianzha County, Qinghai. A randomized complete block design was established, and soil physicochemical properties, microbial biomass carbon/nitrogen/phosphorus (MBC/MBN/MBP), and enzyme activities (urease, phosphatase, and catalase) were measured at 38, 62, and 137 days post-application, while bacterial and fungal community compositions were characterized via high-throughput sequencing of 16S rRNA and ITS2 genes. Our results demonstrated that the wa-60 treatment (30% wheat + 60% alfalfa) outperformed all the other formulations, delivering the highest yield (1.32 ± 0.08 kg/m²) and a 28.6% increase over the control (1.03 ± 0.06 kg/m²; p < 0.01), while maintaining a high total amino acid content (19.8 g/100 g). Soil analysis revealed that wa-60 notably enhanced urease activity (peaking at 85 µg/g/h at day 137) and alkaline phosphatase activity (322.55 µg/g/h), alongside significant increases in MBC and MBN. Microbiome profiling further demonstrated that wa-60 selectively increased the relative abundance of various taxa, particularly the bacterial phylum Bacteroidota and the fungal phylum Mortierellomycota. Correlation analyses indicated strong positive associations among these enriched taxa (primarily at the genus level), enhanced enzyme activities, and improved soil nutrient availability. Collectively, these findings establish that the wa-60 formulation, leveraging locally sourced alfalfa, represents a cost-effective and high-performance strategy for morel cultivation in the Qinghai Plateau, providing a microbial–ecological basis for optimizing ENB design and offering a practical pathway for recycling agricultural waste in edible mushroom production. Full article

The global seafood industry generates substantial quantities of processing by-products such as heads, viscera, skin, bones, scales, and shells. These residues represent an underutilized resource rich in proteins, lipids, minerals, enzymes, and polysaccharides. Conventional valorization approaches such as chemical extraction, wet rendering, and enzymatic hydrolysis have been used to recover valuable compounds from seafood waste. However, conventional methods often involve high chemical consumption, long processing times, and environmental concerns. Green extraction technologies have emerged as promising alternatives, with subcritical water extraction (SWE) gaining significant attention due to its unique properties and ability to simultaneously extract and convert biomass components. This review provides a comprehensive overview of the valorization of seafood processing wastes using SWE. Particular emphasis is placed on the physicochemical properties of subcritical water, the reaction mechanisms governing the hydrolysis and transformation of proteins, lipids, and polysaccharides, and the key parameters influencing extraction performance. Recent advances in the recovery of value-added products such as amino acids, bioactive peptides, protein hydrolysates, omega-3-rich oils, chitin derivatives, and mineral-rich materials are summarized. In addition, the integration of SWE with complementary technologies such as supercritical CO₂ extraction, enzymatic hydrolysis, and hydrothermal carbonization is examined as a strategy for developing integrated seafood biorefineries. Full article

Waste from the aggregate processing industry has the potential to be used for value-added products. Its plastic properties and sinterability allow for the production of lightweight aggregates. This process can yield materials with high open porosity at various scales. This article presents the possibilities of obtaining lightweight aggregates from clay–silt fractions obtained by washing crushed dolomite aggregates. Aggregate formation was achieved using selected mechanical processing methods, such as dynamic granulation, sedimentation, crushing, and classification. Biomass was added to increase the aggregate’s porosity. The following instrumental techniques were used to assess the aggregate’s parameters: X-ray fluorescence (XRF) to obtain detailed information on the oxide composition of the tested raw materials; high-temperature microscopy (HSM) to determine the specific sintering temperature; and pH and conductivity meters to examine filtration solutions in direct contact with the aggregate. A key issue was to examine the microstructure of the produced aggregates after firing using scanning electron microscopy (SEM), Brunauer–Emmett–Teller method for measuring material surface area (BET), and X-ray diffraction (XRD) technique. The obtained results will allow for further research into developing a concept for the production of lightweight alkaline aggregates. The aggregates produced exhibit high water absorption (approximately 50%), a low bulk density of 0.82 g/cm³, and meso- (approximately 30–100 µm) and bioporosity (approximately 100–500 µm), which is beneficial for the proper development of plant roots and the absorption and release of water. This research contributes to the identification of resources that can be transformed into lightweight aggregates for urban greening, which is consistent with circular economy strategies and environmental protection. The specific mechanisms through which this research supports sustainable development are the reduction in landfill sites and the protection of natural resources. Furthermore, the aggregates produced can form part of blue-green urban infrastructure, which aims to manage rainwater and reduce the urban heat island effect. Full article

Biomass, particularly agricultural waste, has emerged as a highly attractive alternative fuel source for domestic and industrial applications. This study investigates the suitability and potential of plantain peel biomass (PPB) as a viable feedstock for bioenergy production. The PPB was comprehensively characterized using proximate and ultimate analyses, thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). Experimental results indicate that the weight ratio of plantain peel (skin) to unpeeled plantains ranges from 27% to 47%. Proximate analysis of the PPB yielded volatile matter (VM) of 65.8% and fixed carbon (FC) of 14.5%, suggesting substantial energy potential. The ultimate analysis results, conducted on a dry, ash-free basis, were used to determine the biomass higher heating value (HHV), which ranged from 13.93 to 16.35 MJ/kg. TGA showed that the thermal decomposition of PPB is typical of lignocellulosic biomass, occurring in three distinct stages over a temperature range of 25 to 1000 °C. FTIR spectroscopy identified O-H and C-H as key functional groups present in the PPB, further supporting its viability for biofuel production. Furthermore, SEM micrographs revealed a porous surface texture with heterogeneous particle sizes and shapes. At the same time, EDS confirmed carbon (C), potassium (K), and oxygen (O) as the dominant elements, alongside trace amounts of magnesium (Mg), silicon (Si), phosphorus (P), chlorine (Cl), and iron (Fe). In conclusion, PPB represents a promising and sustainable feedstock for biofuel production in both domestic and industrial sectors. Full article

In the last few years, the tyre industry has faced new sustainability challenges, mainly regarding the substitution of fossil-based ingredients with bio-based raw materials. In fact, most of the largest tyre companies worldwide have publicly declared the objective of producing tyres with 100% sustainable materials by 2050. The main ingredients in a tyre compound are the polymer matrix and the reinforcing filler, but while natural rubber (NR) already represents a well-established bio-based alternative to synthetic polymers, the replacement of conventional reinforcing fillers remains a significant challenge. In fact, carbon black (CB), a fossil-based raw material produced from petroleum-derived feedstock, is still the main filler used in rubber compounds worldwide. A promising candidate for its replacement could be Microfibrillated cellulose (MFC): a bio-based, biocompatible, renewable, and non-toxic material, also obtained from waste biomass, with a lower density and a higher surface reactivity with respect to CB. However, the polar functional groups on its surface make it extremely incompatible with the non-polar rubber matrices used for tyre formulations. To overcome this limitation, effective compatibility strategies are required to exploit and boost these surface functionalities and promote the formation of a novel filler–polymer network. In this work, a new approach for MFC functionalisation is developed, and the synthesis and characterisation of the modified material are reported. This strategy is further applied to develop innovative MFC-reinforced epoxidised natural rubber (ENR) compounds, whose properties are compared to conventional CB-filled systems. Full article

Sunflower hulls are an abundant lignocellulosic waste with significant but underexploited potential for the recovery of high-value compounds and production of renewable energy. In this study, an integrated biorefinery approach was developed for the sequential recovery of waxes, free and bound phenolic compounds, and biomethane. Three pretreatment strategies (acid-thermal, mechanically assisted alkaline, and ultrasound-assisted ethanolic) were comparatively evaluated to determine their effects on bound phenolics extraction and biomethane production. Sequential extraction recovered 0.94 g of waxes 100 g⁻¹ d.b. and 145.52 mg GAE 100 g⁻¹ d.b. of free phenolics, with chlorogenic acid as the predominant compound. The different pretreatments exhibited contrasting performances depending on the valorisation criterion considered. Although acid–thermal pretreatment achieved the highest recovery of bound phenolic compounds (99.3 mg GAE 100 g⁻¹ d.b.), ultrasound-assisted ethanolic pretreatment preserved the largest proportion of the original biomass and resulted in the highest overall methane recovery (150% relative to the untreated biomass). Each pretreatment modified the lignocellulosic matrix through hemicellulose solubilization, lignin disruption, and fibre reorganisation, thus explaining the observed differences in phenolic release and biomethane production. The results demonstrate that each pretreatment favours a specific product stream, and that the selection of the most suitable pretreatment depends on the biorefinery’s objective. Full article

The essential oil (EO) industry generates large volumes of solid distillation residues that are commonly discarded as waste, despite their potential as a source of nutrients and bioactive compounds. This study evaluated the chemical quality and the volatile profile of four types of exhausted biomasses (EBs) obtained after steam distillation of EOs from bay laurel (Laurus nobilis), lavender (Lavandula angustifolia), lavandin (L. angustifolia × L. latifolia) and two industrial hemp specimens (Carifit1p, a breeding line, and Codimono, a cultivar), with a view to their potential valorisation in animal feeding. The nutritional composition of the distillation residues was determined according to AOAC methods, while the headspace volatile fraction was characterised by HS-SPME–GC/MS. The EBs were generally characterised by a high fibre content, with the highest crude fibre and NDF values in whole lavender and lavandin plants, whereas the industrial hemp line Carifit1p showed the highest crude protein (17.1% DM) and ash contents. The volatile profiles of the residues differed markedly from those typical of the corresponding fresh EOs: the bay laurel residue was dominated by monoterpene hydrocarbons (74.5%) with strongly depleted 1,8-cineole (1.9%), while lavender and lavandin retained high levels of β-caryophyllene (35.8% and 32.4%, respectively). Industrial hemp residues were enriched in oxygenated sesquiterpenes, with caryophyllene oxide reaching 21.2% in Carifit1p and exceeding β-caryophyllene. Overall, the results indicate that EO exhausted biomasses retain a species-specific profile of fibre, residual nutrients and less volatile, less water-soluble terpenoids, supporting their potential reuse as feed ingredients and contributing to a more sustainable, near-zero-waste distillation supply chain. Full article

Residual avocado biomass, primarily peel and seed generated during industrial processing of Persea americana Mill., represents an abundant agro-industrial residue with considerable potential for sustainable valorization. This review critically examines the biotransformation of residual avocado biomass into humic substances (HS) through composting, integrating current knowledge on substrate composition, microbial succession, biodegradation kinetics, humification mechanisms, and process-control strategies. A systematic literature review was conducted following the PRISMA framework, enabling the identification and critical evaluation of recent advances in composting technologies, kinetic modeling, and humification processes specific to avocado residues. Particular emphasis is placed on the influence of key operational variables—including temperature, moisture, aeration, C/N ratio, pH, and microbial activity—on organic matter degradation, nitrogen conservation, compost stability, and HS formation. The review also discusses maturity and quality indicators, including the humification index, E4/E6 ratio, germination index, and leachate management, together with the role of vermicomposting and cascade biorefinery approaches in maximizing resource recovery. Current evidence indicates that residual avocado biomass constitutes a promising feedstock for producing stable humified organic amendments while contributing to nutrient recycling, soil fertility, carbon sequestration, and circular bioeconomy strategies. Finally, major research gaps are identified, particularly regarding avocado-specific biodegradation kinetics, integrated process monitoring, predictive modeling, and intelligent process-control systems, providing future directions for the optimization and industrial implementation of composting technologies for sustainable agro-industrial waste valorization. Full article