Search Results (1,025)

Vermicomposting is an environmentally sustainable, economically viable, and agronomically valuable method for converting organic waste into nutrient-rich soil amendments, thereby supporting sustainable development. However, the fertilization efficiency of vermicompost can vary significantly depending on the physicochemical properties of the feedstock used. This study aims to compare different feedstocks on vermicompost and evaluate their performance on soil fertility and plant nutritional status. Organic matter (OM), pH, salinity (EC), total Kjeldahl nitrogen (TKN), total phosphorus (TP) and total potassium (TK) of various vermicompost samples were taken into consideration to evaluate their fertilization efficiency as performance determinants in terms of plant growth, plant nutritional status, yield, crop quality and cost with the aim of determining the weights of the specific parameters in the total performance using multi-criteria decision-making (MCDM) methods. The integrated ENTROPY-TOPSIS method was used. Twenty-one different vermicompost feedstock analyses were collected from the literature and compared in order to create an agronomic performance ranking based on the selected criteria. The ENTROPY method revealed that the TP was the most influential factor (21.6%), followed by the EC (20.7%) and the TK (18.5%), while the OM had the lowest impact (11.3%). Based on the TOPSIS ranking, vermicompost from brewer’s spent grain achieved the highest performance, followed by cow manure plus rice straw and olive pruning waste, whereas paper waste ranked at the bottom. A comparative analysis with other objective MCDM weighting methods proved strong correlations, particularly with WENSLO, MPSI and LODECI methods, confirming the robustness of the ENTROPY method. Full article

Efficient use of agro-industrial residues is central to developing a circular bioeconomy. In this study, apple pomace was used as a feedstock for fermentation with water kefir cultures to investigate the formation of bioactive compounds and evaluate their functional biological effects. The effects of fermentation in a cement tank were compared to a reference fermentation system using a conventional glass vessel, focusing on physicochemical parameters and biological activity. Despite differences in pH evolution, no significant differences between the two fermentation systems were found in antioxidant capacity, total phenolic and carotenoid content, or inhibitory activity against platelet aggregation. Lipid extracts from both systems showed strong antioxidant properties and pronounced inhibitory activity against platelet-activating factor (PAF)- and ADP-induced aggregation, with significantly lower IC₅₀ values for PAF (p < 0.05), indicating enhanced anti-inflammatory specificity. These effects may be attributed to the synergistic interaction of fermentation-derived bioactives, including polar lipids, aglycone flavonoids, and carotenoids. Importantly, fermentation in a cement tank did not compromise biofunctional performance, highlighting its potential as a low-cost and scalable alternative for bioprocessing. Overall, these findings demonstrate that water kefir fermentation can efficiently convert low-value fruit residues into bioactive-rich matrices, providing a sustainable and environmentally friendly approach aligned with EU and UN circular economy frameworks for waste reduction and resource valorization. Full article

Triacylglycerols (TAGs) are essential energy reservoirs and industrial raw materials, while structured TAGs (STAGs) with tailored fatty acid distributions possess unique nutritional and functional values but low natural abundance. Enzymatic synthesis is strictly limited by feedstock and cost, making microbial de novo synthesis via metabolic engineering a promising alternative. This review summarizes advances in the fatty acid biosynthesis pathway and its regulation, key enzymes in TAG synthesis (GPAT, LPAAT, and DGAT), and microbial production of major STAGs (OPO, MLM, CBEs, and PUFA-rich STAGs). Current challenges and future perspectives are also discussed, promoting the shift toward rational design of functional STAGs. Full article

Fatty alcohols and aliphatic hydrocarbons occur abundantly in nature and serve as critical feedstocks for the surfactant and fuel industries, respectively. However, their industrial-scale separation and purification are significantly hampered by high boiling points and the formation of complex azeotropes. To address these challenges, this study explores a five-column high-vacuum pressure-swing distillation (HVPSD-5C) strategy. Vapor–liquid equilibrium (VLE) analysis of the key components (n-hexanol, n-octanol, n-dodecane, and n-tridecane) validated the thermodynamic viability of the process and established optimal operating conditions. To further enhance efficiency, a heat-pump-integrated configuration (HPI-HVPSD-5C) featuring vapor recompression and heat integration was designed, optimized, and evaluated. Comparison with the baseline HVPSD-5C process demonstrates that the HPI-HVPSD-5C configuration significantly improves sustainability and economics, reducing the total annual cost (TAC) by 17.48%, CO₂ emissions by 16.09%, and energy consumption cost by 12.79%. These findings provide a robust framework for the efficient separation of fatty alcohols from aliphatic hydrocarbons, offering a valuable reference for the purification of other pressure-sensitive azeotropic mixtures. Full article

Sustainable production in dental and orthodontic 3D printing has gained increasing attention due to environmental concerns and the need for cost-effective and resource-saving solutions. This study presents a proof of concept for using recycled polymers and fused granular fabrication (FGF) in a closed-loop 3D printing approach, omitting intermediate filament manufacturing. A desktop 3D printer served as the kinematic platform and was modified with a pellet-based extruder to directly process recycled polyethylene terephthalate glycol (PETG) flakes, obtained by shredding previously printed PETG parts, into dental models. Dimensional accuracy was evaluated using optical 3D scanning analysis. The results indicate that models produced from recycled PETG are, in principle, suitable for dental and orthodontic applications within the investigated scope. This technical note provides initial evidence supporting the integration of recycled thermoplastics into dental and orthodontic model fabrication as part of sustainable additive manufacturing workflows. Potential pathways for workflow integration in clinical and laboratory environments, as well as directions for future research, are outlined, including the optimization of printing parameters and process stability. The main technical challenges were unreliable feedstock flow, causing bridging and jamming, while thermal creep from insufficient inlet cooling promoted premature softening of the flakes, causing torque spikes and unstable feeding. Full article

Biosurfactant production by hydrocarbon-degrading bacteria is strongly influenced by the nature and concentration of available carbon substrates, which determine hydrocarbon bioavailability and microbial metabolic responses. In this study, five Bacillus subtilis strains isolated from weathered oil-contaminated sites in Qatar were evaluated for growth and biosurfactant activity using diesel fuel, fresh corn oil, and five-times-overheated corn oil as sole carbon sources. Cultures were grown in mineral salts medium under controlled conditions, and biosurfactant production was assessed through emulsification activity (EA), solubilization activity (SA), and colony-forming unit counts. All strains grew on the tested substrates but exhibited distinct strain-specific responses. Fresh corn oil supported the highest biomass production with values up to 3.3 × 10⁷ CFU mL⁻¹, whereas the strongest emulsification activity yield was observed in diesel cultures at low carbon loading (59 ± 2.3 EU g⁻¹ carbon. Five-times-overheated corn oil maintained more stable emulsification activity across a broader concentration range, indicating tolerance to oxidized hydrocarbons and adaptation to chemically altered substrates. Increasing hydrocarbon concentrations led to progressive declines in EA and SA, indicating inhibitory effects at high substrate loads. Overall, biosurfactant production did not correlate directly with biomass, highlighting the importance of substrate properties in regulating functional output. These findings demonstrate that substrate composition and concentration are key determinants of biosurfactant performance in B. subtilis isolates and support the potential use of waste oils as low-cost feedstocks for biotechnological and bioremediation applications. Full article

Effective management of organic wastes is essential for green and low-carbon development. Conventional technologies, including incineration, pyrolysis, hydrothermal carbonization (HTC), gasification, anaerobic digestion (AD), and composting, have supported waste reduction and basic resource recovery, but they remain limited in high-efficiency conversion and high-value utilization. This review comparatively evaluates these conventional routes together with advanced and intensified technologies, including microwave-assisted pyrolysis (MAP), plasma treatment, supercritical water gasification (SCWG), and flash joule heating (FJH), with emphasis on suitable feedstocks, performance characteristics, application boundaries, and integration potential. In general, wastes with high moisture content are more suitable for HTC, AD, and SCWG, whereas relatively dry wastes and wastes with high carbon content are more suitable for pyrolysis, gasification, plasma treatment, and FJH upgrading. The review also discusses representative integrated pathways, such as HTC-SCWG, pyrolysis and plasma coupling, AD and gasification coupling, and pyrolysis and FJH coupling, which may improve carbon conversion, broaden product portfolios, and reduce residual pollutants. However, large-scale implementation is still constrained by feedstock heterogeneity, heat and mass transfer limitations, catalyst deactivation, reactor corrosion, and system cost. Overall, no single technology is universally optimal; technology selection should depend on feedstock properties, moisture content, and target products. Full article

The continuous increase in Renewable Energy Sources (RES) in Greece’s electricity system has led to growing energy curtailment due to limited grid capacity, especially in high-production regions. According to recent data, more than 200 GWh of clean energy was curtailed in a single quarter in 2024, highlighting the urgent need for effective storage solutions. Curtailment represents a growing system level challenge, but it also creates an opportunity to convert surplus renewable electricity into green hydrogen through electrolysis. This study quantifies the hydrogen production potential of curtailed RES electricity in four Greek regions, Peloponnese, Crete, Thrace, and Western Macedonia, and evaluates alternative storage pathways under harmonized techno-economic assumptions. A scenario-based framework is developed using regional RES capacity, curtailment estimates, electrolyzer efficiency, hydrogen conversion factors, and indicative storage cost ranges. The analysis compares pressurized tank storage, underground storage, and hybrid configurations, while also estimating avoided CO₂ emissions from the substitution of grey hydrogen. The results indicate substantial regional variation. The Peloponnese exhibits the highest annual hydrogen potential, followed by Crete, Thrace, and Western Macedonia, while each region presents different infrastructure constraints and deployment roles. Mainland regions with access to geological storage show lower indicative hydrogen costs than island systems, where storage and export constraints increase costs. The findings show that curtailed renewable electricity can function as a low-carbon feedstock for hydrogen production in Greece, supporting grid flexibility, regional decarbonization, and the gradual development of hydrogen hubs under differentiated regional strategies. Full article

The growing worldwide need for sustainable, high-quality protein sources has intensified interest in single-cell protein (SCP) production, particularly mycoproteins derived from filamentous fungi. This shift is further driven by global sustainability priorities articulated by regulatory bodies, which promote resource efficiency, waste valorization, and sustainable food systems. Despite their high carbohydrate potential, the agricultural sector generates vast quantities of starch-rich by-products. Examples include broken rice, cassava peels, potato waste, and cereal-processing residues, which remain largely underutilized and thereby contribute substantially to environmental pollution. This literature review examines the potential of starch-based agricultural by-products as low-cost, renewable feedstocks for fungal SCP production in support of the Sustainable Development Goals (SDGs). These by-products include broken rice, cassava peels, potato waste, and cereal processing residues, which remain largely underutilized despite their high carbohydrate content. Key topics include pretreatment strategies, fungal fermentation with Neurospora and Fusarium spp., and process optimization to maximize biomass yield and feedstock valorization. Life cycle assessments (LCAs) indicate reduced greenhouse gas emissions compared with conventional protein sources, highlighting the potential of starch residues in circular bioeconomy systems. Furthermore, considerations related to process design, environmental benefits, and techno-economic feasibility are evaluated in the context of converting starch residues into fungal protein. In summary, the evidence suggests that valorizing starch by-products for mycoprotein fermentation, used both as a protein alternative and as an ingredient, represents a promising strategy to reduce waste management and production costs and support global food sustainability. Full article

Lignocellulosic wastes are low-carbon, renewable and sustainable feedstocks for replacing fossil fuels in the production of energy and chemical products. However, the bioconversion of lignocellulose into biofuels or biochemicals is costly. To address the high cost, this study extracted essential oil (EO) from ginger stalks and leaves (GSL) as an antioxidant to valorize the bioconversion process of GSL. The Box–Behnken design was used to optimize EO extraction, and the maximum EO yield of 2.99% was obtained under the optimal condition of KOH infiltration for 26 h, extraction for 3 h, and an n-hexane-to-GSL ratio of 8 (v/w). With 95% n-hexane recovery and no generation of waste liquid during the extraction process, fugitive emissions and solvent waste were reduced, enhancing sustainability. The EO’s antioxidant activity exceeded that of commercial ginger EO. The combined process of KOH infiltration and n-hexane extraction induced physicochemical changes in GSL and improved its enzymatic hydrolysis efficiency from 2.70% to 69.09%. According to the economic assessment, the bioconversion of GSL into bioethanol would benefit from the EO product, with the on-site production cost of cellulase being no more than 0.98 USD/kg. This study presents a feasible and sustainable case for lignocellulosic biorefining. Full article

Indisputably, the evolution of innovative manufacturing methods such as additive manufacturing (AM) or 3D printing in the last decade has started gradually to influence the construction field, offering significant benefit potential, particularly in the field of metallic materials. In the case of aluminium alloys, the implementation of the wire arc additive manufacturing (WAAM) method, an AM sub-type, has recently emerged as a promising alternative to conventional rolling and extrusion, enabling unprecedented geometric flexibility, lower energy demand, and reduced tooling costs. However, the selection of an appropriate feedstock alloy poses a major challenge, as inherent trade-offs between strength, ductility, and printing-induced anisotropy arise. In this context, this study presents a thorough multi-scale numerical investigation, spanning from the cross-sectional to the global structural scale. The structural performance of several two-story moment-resisting frames was evaluated, comparing frames featuring WAAM-fabricated columns against conventional extruded and rolled benchmarks. The assessment included three 3D-printed alloys (Al-Mg, Al-Cu, Al-Mg-Si), differing in ductility levels, featuring topology-optimized and internal lattice-reinforced cross-sectional geometries. Linear elastic analyses reveal that global lateral stiffness heavily governs the response of slender frames, where WAAM was able to efficiently decrease the corresponding inter-story drifts by maximizing cross-sectional inertia without necessitating the utilization of larger external member dimensions. Furthermore, nonlinear static (pushover) analyses provided valuable insight into critical design considerations, exposing a profound strength-ductility trade-off in printed aluminium alloy load-bearing members. Full article

This review analyzes the advances over a five-year period in the development of polymeric sorbents for the purification of aqueous media from key classes of pollutants: hydrocarbons (crude oil, diesel fuel), organic dyes, pharmaceuticals (antibiotics), pesticides, herbicides, volatile organic compounds, and polycyclic aromatic hydrocarbons. Attention is paid to the analysis of structure-property-performance relationships, with an emphasis on comparing materials derived from renewable natural feedstocks (such as cellulose, chitosan, terpenes, vegetable oils, and aloe vera) with synthetic polymers. The analysis reveals that biopolymer-based sorbents exhibit comparable or superior sorption capacities combined with environmental safety, biodegradability, and low cost. The key sorption mechanisms include physical adsorption, hydrophobic interactions, and electrostatic interactions. Despite persisting challenges related to scalability, stability in real-world environments, and the need for efficient regeneration protocols, a convergent approach that combines the advantages of modified natural polymers and functional synthetic components appears to be the most promising strategy for developing cost-effective and sustainable technologies for the restoration of water quality. Full article

This study examines the economics of blue and green hydrogen as feedstock for large industrial facilities in Southeast Asia. To understand how industries can adopt low-emission and renewable hydrogen, the levelised costs of blue and green hydrogen are calculated. Four pathways are examined, including a large-scale carbon capture and sequestration facility located a distance away from an existing steam methane reforming hydrogen plant, a gigawatt-scale electrolysis facility adjacent to a large industrial site fed by an adjacent solar photovoltaic electricity source, as well as two pathways with either remote electrolyser and solar photovoltaic, necessitating hydrogen transport and storage, or a remote solar photovoltaic source with a dedicated power transmission line. The region’s transition to green hydrogen must overcome the challenges of high renewable electricity costs, the need for large land banks for solar photovoltaic farms and efficient long-distance hydrogen transport solutions or power transmission lines. Moreover, the region must improve its inconsistent track record in implementing billion-dollar public–private projects within budget and on time. Full article

The accumulation of petroleum-based plastics demands sustainable alternatives such as polyhydroxyalkanoates (PHAs), biodegradable polyesters synthesised by numerous prokaryotes. However, high feedstock costs limit their commercialisation. This study evaluated cocoa mucilage, an underutilised by-product of the Ecuadorian cacao sector, as a low-cost carbon source for PHA production by a wild-type strain isolated from cocoa fruit residues. Bacteria were recovered from cocoa mucilage and pod shell fractions and screened for PHA accumulation by Sudan Black B staining with UV–Vis spectrophotometric confirmation. A single PHA-positive isolate, designated Priestia aryabhattai strain NBP01-UTN (GenBank accession OR567321.1; 99.88% 16S rRNA gene sequence identity to the type strain B8W22T), was recovered from the cocoa shell surface—representing, to the best of our knowledge, the first report of a PHA-producing P. aryabhattai from cacao fruit residues. Fermentation conditions were optimised using the response surface methodology with a central composite design evaluating temperature, pH, and ammonium sulphate concentration. The fitted quadratic model was highly significant (R² = 0.978, p < 0.0001), indicating that temperature and nitrogen limitation were the dominant factors. Optimal conditions (40 °C, pH 7.30, 0 g·L⁻¹ (NH₄)₂SO₄) yielded 0.496 g·L⁻¹ PHA at 24 h (productivity ≈ 20.7 mg·L⁻¹·h⁻¹). Notably, no external nitrogen supplementation was required, as the endogenous nitrogen in cocoa mucilage sufficed to sustain growth whilst triggering the nutrient imbalance needed for PHA biosynthesis. FTIR and DSC analyses provided spectroscopic and thermal evidence consistent with poly(3-hydroxybutyrate) (PHB), although definitive monomer-level confirmation requires GC–MS or NMR spectroscopy. These results demonstrate the feasibility of coupling a locally isolated wild-type strain with cocoa mucilage to produce bioplastic within a circular bioeconomy framework. Full article

Bioplastics are increasingly expected to function not only as alternatives to fossil-derived plastics but also as components of circular plastic systems. However, currently bioplastics remain limited by cost, feedstock availability, achievable biomass content, and end-of-life compatibility. This review examines these limitations by organizing recent technological and policy trends in bioplastics, with particular attention to Japan’s social and industrial infrastructure. On this basis, we discuss a systems-level framework for circular plastics that integrates regionally underutilized non-edible biomass, decentralized production concepts, and the emerging possibility of cell-plastics based on unicellular green algae. We argue that the practical dissemination of biomass plastics requires not only material development but also compatibility with molding processes, recycling and biodegradation pathways, and regional collection and treatment systems. In this context, cell-plastics derived from Chlamydomonas reinhardtii are positioned as an emerging technological platform for direct biomass utilization and interfacial material design, although their large-scale implementation remains limited by current cultivation and manufacturing constraints. We propose that circular biomass-plastics systems in Japan should be developed as regionally adapted production frameworks with clearly defined end-of-life pathways, rather than as simple substitutes for petroleum-derived plastics. Full article