Search Results (769)

Mixed cotton–polyester textile waste remains difficult to recycle because processes that recover synthetic polymers often leave the cotton fraction underused, while cellulose extraction methods may compromise the polyester component. This study investigates whether cotton in such blends can be converted into high-quality microcrystalline cellulose while retaining the potential value of the recovered polyester fraction. Cotton waste and cotton–polyester blends were treated using aqueous sulfuric acid at different conditions: from 15 to 20% acid concentration and from 70 to 80 °C for five to ten hours. The recovered microcrystalline cellulose was characterised and compared to commercial microcrystalline cellulose, while the polyester fraction was assessed using tensile testing. Enzymatic hydrolysis and a dimethyl sulfoxide co-solvent approach were evaluated as alternatives. The aqueous acid process yielded 82 to 97% microcrystalline cellulose from cotton waste and up to 51% from blended waste. The recovered cellulose showed around 10% higher crystallinity than commercial material and a similar particle size distribution, although morphology depended on the feedstock. The polyester fraction showed only minor reductions in tensile performance. The novelty of this study lies in the demonstration of a simple, ionic-liquid-free, single-reagent route that valorises both material streams from cotton–polyester textile waste. Full article

High-ammonium poultry digestate from thermophilic dry anaerobic digestion is often recycled, but excessive ammonia accumulation may inhibit anaerobic digestion and reduce process stability. This study developed a gas-driven ammonia stripping process coupled with gypsum-mediated absorption for digestate deammonification, nitrogen recovery, and CO₂-assisted carbonate formation. Laboratory stripping experiments were conducted using simulated biogas to evaluate the effects of pH, temperature, and gas–liquid ratio. Under the selected condition of pH 11, 65 °C, and a gas–liquid ratio of 2, NH₄⁺-N in 10 L digestate decreased from approximately 7980 to 1648 mg L⁻¹ within 12 h, corresponding to about 80% removal. In the absorption step, the slightly soluble CaSO₄ solution showed more stable NH₃ capture than the CaSO₄ suspension, and the corrected NH₃-N recovery reached approximately 90–95%. XRD, SEM-EDS, precipitate mass estimation, and gas-phase CO₂ variation supported the formation of CaCO₃-containing precipitates. Pilot-scale operation using real biogas further reduced NH₄⁺-N from approximately 8000 to 700–800 mg L⁻¹ during 36 h of extended pilot-scale operation. Overall, the coupled process provides a preliminary resource-recovery route integrating ammonia burden reduction, nitrogen recovery, sulfate transfer, and CO₂-assisted carbonate precipitation. However, full-scale sustainability still requires further long-term operation, complete nitrogen–carbon–calcium–sulfur mass balances, complete heat and energy-balance assessment, product-quality evaluation, and techno-economic or life-cycle assessment. Full article

Paper-based packaging is widely promoted as a sustainable alternative to plastic; however, functional coatings can reduce fibre integrity and lead to burden shifting in industrial recycling systems. This review examines how these effects undermine the environmental benefits expected from fibre-based packaging and weaken progress towards high-quality circularity, as required by current EU sustainability policy. By comparing leading assessment schemes (PTS, CEPI, 4evergreen) with industrial evidence, we identify a systemic gap: laboratory-focused recyclability tests often overlook fibre-quality degradation and the resulting limitations for circular material loops. To close this gap, we propose a sustainability-oriented extension module based on three measurable ISO-anchored indicators—fibre length, fines fraction and WRV—that prevent “recyclable-only-on-paper” claims and support genuinely sustainable recycling performance. Case studies demonstrate how high laboratory yields can mask low industrial recyclability and thus hinder circular economy objectives. This study contributes to sustainability science by operationalising recyclability in a manner consistent with EU circularity goals and by providing a transparent method to protect fibre value in multiple loop cycles. Full article

As sustainable agriculture continues to develop, straw recycling has become an effective step for conserving agricultural residues. In practice, farmers submit recycling requests to an enterprise, which then dispatches balers before arranging transporters. This sequential planning process creates delays between baling and transportation and increases total costs. A synchronized baling transportation framework is developed in this study. A joint optimization model is formulated to minimize total costs, and a Branch and Bound Algorithm strengthened with strong valid inequalities is developed to solve it. Numerical experiments using data from Heilongjiang, China, show that the proposed approach obtains high-quality solutions within reasonable computation times and lowers total cost. This study offers a practical method for the operation and management of straw recycling enterprises. Full article

The engineering, resource, and financial constraints in space and spacecraft so far have not allowed the incorporation of biological components into a closed-loop bioregenerative life support system (BLSS), despite decades of research. The expected increase in deep-space exploration and planetary bases with limited access to Earth-based resources necessitates the development of self-sustaining hybrid BLSS technology. The created physicochemical systems, together with photosynthetic organisms and bacteria, aim to revitalize the air, produce food, and recycle nutrients and water in mutually beneficial mini-ecosystems. While plants are best in the function of food production and bacteria in waste recycling, the incorporation of microalgae would add immense benefits in optimizing the life support system (LSS) and increasing the degree of closure. Microalgal photobioreactors (PBRs) could perform wastewater treatment (WWT), removing the nitrogen (N) and phosphorus (P) in the human-derived wastewater (WW), and couple it with converting carbon dioxide (CO₂) from the cabin to oxygen (O₂) and food production. As microalgal WWT on Earth is an emerging field with engineering hurdles, power, mass, volume, microgravity fluid dynamics, and other constraints have also prevented their operations in space. However, in space vehicles, there is no need for large upscaling of a laboratory prototype system, and the WW effluent is easier to predict, facilitating microalgal extraplanetary use in comparison to Earth treatment plants. These factors, combined with the qualities of microalgae such as surface-to-volume efficiency, fast growth rate, high yield, and tolerability to WW, etc., have led to many preliminary testbeds, prototypes, and ground demonstrations from space agencies, space centers, and academia, which show promising results. Microalgal participation in space WWT is beyond current operational practice; however, PBRs are on the space agenda, and the scientific community is elaborating the technologies that would allow their successful implementation. Full article

The present study aims to address critical research gaps in duckweed–microbe symbiotic systems specifically applied to high-load livestock and poultry breeding wastewater. These gaps include the insufficient development of well-characterized, multi-functional, complex microbial consortia adapted to complex livestock wastewater matrices, and the technical challenge of achieving simultaneous efficient wastewater purification and duckweed feed quality enhancement. This study is motivated by the pressing issue of agricultural non-point source pollution, which is caused by large-scale livestock and poultry breeding wastewater discharge, and the high external dependence of the feed industry on protein raw materials. The present study utilised Spirodela as the fundamental material, and a functionally complementary complex symbiotic bacterial consortium consisting of Bacillus subtilis, Bacillus tequilensis and Pseudomonas fluorescens was screened and constructed. An experiment was conducted over a 14-day period in which a range of inoculation ratios were systematically explored. The aim of this experiment was to ascertain the purification efficiency of the duckweed–bacteria symbiotic system on high-load livestock and poultry breeding wastewater. Furthermore, the experiment sought to determine the effect of this purification process on the feed value of duckweed. The results demonstrated that complex bacterial inoculation significantly enhanced wastewater purification efficiency. The final removal rate of ammonia nitrogen in all treatment groups exceeded 90% after 14 days, and the maximum removal rates of total nitrogen and total phosphorus reached 67.0% and 58.9%, respectively, thereby demonstrating superior purification performance in comparison to the control group. The inoculation ratio of 10:1 was identified as the optimal parameter for wastewater purification, while the 5:1 ratio was found to be the maximum for crude protein accumulation in duckweed. The maximum dry-based crude protein content recorded was 38.9% on day 14, representing an increase of 26.3% in comparison with the control group. The established duckweed–bacteria symbiotic system has the capacity to simultaneously achieve the efficient purification of livestock and poultry breeding wastewater and the high-value utilisation of duckweed. The optimal process parameters for a range of application scenarios have been determined. This study contributes to the theoretical framework of aquatic plant–microbe symbiotic remediation and provides technical support for the recycling of wastewater resources and the sustainable development of the livestock and poultry breeding industry. Full article

The significant CO₂ emissions from cement manufacturing and overuse of natural aggregates, especially river sand mining, have been a global environmental concern for decades. This is a review study that aimed to evaluate the solution by reviewing past studies on the incorporation of supplementary cementitious materials (SCMs) and recycled aggregates (RAs) to produce sustainable concrete (SC). Regarding environmental consequences, the results highlighted that the cement industry accounts for a 5–8% carbon footprint. Concurrently, the demand for high-quality river sand has escalated, leading to widespread river degradation, altered channel morphology, and effects on river ecosystems. Past studies’ experimental results indicate that silica fume (SF), as an effective SCM, enhances the strength and durability of sustainable concrete to its optimal levels. However, the higher RA content resulted in reductions in engineering properties. The published studies also reported that lower percentages of SF combined with RAs had a positive effect on the strength and durability of design mix concrete, thereby further strengthening the findings of this review. This factor was found to be missing in most studies. A cost–benefit analysis for combined SCMs and RAs was introduced in this study. This review study evaluated the cost–benefit analysis of 1 m³ of sustainable concrete. The highest benefit was observed at 20.97% in a study when optimized 10%SF + 100 RAs were combined. It showed that the combined use of SCMs with RAs at optimal levels satisfied the strength and durability requirements. In addition, the benefits of sustainable concrete were achieved without any cost increase, a new outcome revealed by this review. Full article

Waste lubricating oils (WLOs) represent a major stream of hazardous petroleum-based residues, with global generation exceeding 24 million tons annually. Improper disposal of WLOs poses risks to soil, water, and air quality, while their chemical composition makes them a potential secondary resource within circular economy frameworks. This review summarizes conventional, advanced, and emerging technologies reported for the recycling and valorization of WLOs into high-value petrochemicals and carbon-based materials. Established processes such as acid–clay treatment, solvent extraction, and vacuum distillation are discussed together with more recent approaches, including catalytic upgrading, hydrotreatment, membrane separation, and thermochemical conversion methods such as pyrolysis and catalytic cracking. Reported data on process performance, environmental considerations, techno-economic indicators, and life cycle assessment outcomes are comparatively analyzed to outline current trends, technical challenges, and future development directions in WLO recycling. Particular attention is given to thermochemical pathways capable of generating carbonaceous materials, including carbon black, porous carbons, and functional carbon nanostructures with potential applications in adsorption, catalysis, electrochemical systems, and tribological formulations. Hybrid and integrated process configurations described in the literature are highlighted for their potential to improve recovery efficiency, enhance product quality, and reduce environmental burdens. In addition, recent life cycle assessment (LCA) and techno-economic analysis (TEA) studies are reviewed to provide insight into the environmental and economic implications of advanced re-refining systems. Overall, the reviewed literature indicates that WLO recycling represents not only an important element of sustainable lubricant management but also a promising waste-to-carbon strategy for the production of value-added carbon-based materials and petrochemical products. Full article

Basalt-fiber-reinforced recycled aggregate concrete (BFRAC) produced with 100% recycled coarse aggregate is still constrained by the inferior quality of recycled aggregate and the difficulty of optimizing fiber reinforcement parameters. This study investigated the effects of basalt fiber length configuration and dosage on the mechanical performance and pore structure of recycled aggregate concrete incorporating recycled coarse aggregate subjected to two-step pretreatment with nano-silica and cement slurry. Four fiber length configurations, namely 6, 12, and 24 mm and a mixed-length system, were evaluated at volume fractions of 0.1, 0.2, and 0.3%. The reinforcing effect was assessed through compressive strength, splitting tensile strength, scanning electron microscopy, mercury intrusion porosimetry, and statistical analysis. The pretreatment improved recycled aggregate quality, reducing water absorption from 4.97% to 3.11% and crushing index from 20.5% to 13.4%. Basalt fiber incorporation generally enhanced mechanical performance, although the response depended on fiber length and dosage. At 28 days, BF24V1 achieved the highest compressive strength, whereas BFmixV1 exhibited the best overall performance by combining high compressive strength with the highest splitting tensile strength. Relative to the average performance of the corresponding single-length mixtures at the same dosage, the mixed-length system showed a positive synergistic effect. Microstructural observations indicated that this behavior was associated with more effective crack bridging and refinement of the pore-size distribution. The results demonstrate that a low-dosage mixed-length basalt fiber system provides an effective route for upgrading pretreated waste-derived aggregate into higher-performance recycled aggregate concrete. Full article

In this work, we introduce the novel possibility of producing blue fluorescent ultraviolet pigments from phosphogypsum. The obtained materials are characterized by X-ray diffraction (XRD), transmission electron microscopy, and X-ray photoelectron spectroscopy (XPS). The formation of the CaS phase in the sample during the reduction of calcium sulfate was established. Thermal treatment of phosphogypsum in the presence of a reducing agent (potato starch) under environmental isolation conditions is found to yield high-quality products with high added value. The highest luminosity is established in samples containing 0.6 mol. %, which were heat-treated under a temperature of 1100 °C for 60 min. The synthesized CaS:Cu materials are shown to emit light in the blue region of the spectrum, with an emission maximum at a wavelength of 480–490 nm. The developed technological methods open the possibility to recycle chemical industry waste, which contributes to the achievement of sustainable development goals, in particular, the goal of ensuring rational consumption and production patterns. Full article

Steel dust is a waste generated during steelmaking in an electric arc furnace (EAF), which contains a high proportion of iron-bearing compounds, leading to the inclusion of this waste as a resource in the circular economy for steelmaking. In addition to the limitation related to granulation (the waste must be processed to obtain larger particle sizes), a limiting factor is the increasingly high Zn content due to the low-quality ferrous charge. For the recycling of steelmaking dust, preliminary processing is necessary to reduce zinc. The paper presents, in addition to qualitative characterization of steel dust, laboratory experiments on the compositional changes associated with zinc redistribution applying the hydrometallurgical leaching process in an alkaline environment, using sodium hydroxide (NaOH). The changes in the chemical composition were identified and evaluated using X-ray fluorescence (XRF) and energy-dispersive X-ray spectroscopy (EDX). The experiments consisted of treating steel dust samples with 5 M NaOH at 25, 70, 80 and 90 °C for 60 min, using solid-to-liquid ratios of 10, 15, and 25 g/L. The results indicate a reduction in ZnO content ranging from 4.52% to 16.82%, as determined from Na₂O-free normalization data. Room-temperature samples show only marginal changes in ZnO content. The XRF and EDX analyses indicate a moderate and condition-dependent redistribution of zinc in the solid phase after alkaline treatment, as evaluated using Na₂O-free normalized data. These values are derived exclusively from solid-phase measurements (XRF/EDX) and do not include zinc in the leachate; therefore, true zinc extraction efficiency cannot be determined. The research results attest to the viability and efficiency (as a solid-phase compositional transformation process) using NaOH as a leaching agent for the studied steel dust, thus providing a potential pathway for improved waste recycling in the steel industry. Full article

Glycolysis of poly(ethylene terephthalate) (PET) offers a promising route for chemical recycling, yet conventional homogeneous catalysts often suffer from low selectivity, severe side reactions (especially diethylene glycol, DEG formation), and detrimental metal residues that compromise the quality of recycled products. To address these challenges, we herein develop dipotassium phenylphosphonate (PPOA-K) as an efficient homogeneous catalyst for PET glycolysis. Under optimized conditions (1 wt% catalyst, 197 °C, EG/PET mass ratio 3:1, 90 min, atmospheric pressure), PPOA-K achieves 100% PET depolymerization and a high BHET yield of 86.0%, and the reaction follows apparent first-order kinetics with an activation energy of 70.3 kJ·mol⁻¹. Beyond its high catalytic activity, PPOA-K effectively suppresses the acid-catalyzed etherification of ethylene glycol to DEG, a common side reaction that reduces monomer purity and degrades recycled polyester properties. Remarkably, the trace amount of PPOA-K remaining in the recovered BHET (17.3 ppm) is not detrimental; instead, it continues to inhibit DEG formation during repolymerization and acts as a thermal stabilizer, improving the melting point and thermal stability of recycled PET. The advantages of PPOA-K are further demonstrated in a partial (in situ) glycolysis–repolymerization process, where it reduces the DEG content in the final rPET to 1.78% (vs. 2.25% for conventional Zn(OAc)₂), yielding rPET with a higher melting point, higher crystallinity, and better color. This work demonstrates that dipotassium phenylphosphonate uniquely combines high catalytic activity, side reaction suppression, and beneficial residue effects, offering a new catalyst design strategy for high-quality PET recycling. Full article

Residual volatile organic compounds (VOCs) and non-intentionally added substances (NIASs) limit the reuse of post-consumer recycled high-density polyethylene (rHDPE) in high-value applications because they generate persistent odors and may compromise product quality and regulatory acceptance. This work comparatively assesses five deodorization and purification routes for rHDPE: agitation washing, ultrasound-assisted washing, reflux heating, Soxhlet extraction, and dissolution/precipitation, by combining VOC removal performance, material characterization, and techno-economic evaluation. Ultrasound-assisted washing with SDS achieved ~96% total VOC removal, while reflux heating resulted in near-complete removal (~98%), approaching the analytical detection limit. Soxhlet extraction with ethanol reached 94% after 1 h, and the dissolution/precipitation method provided near-complete purification and removed additional impurities, but at the expense of substantially higher process complexity and cost. Mechanical and physicochemical characterization indicated that the evaluated treatments did not appreciably compromise the measured properties of the recycled polymer. In addition, equilibrium screening with representative analytes in ethanol provided qualitative support for the solvent–polymer interaction discussion. A plant-scale techno-economic assessment identified ultrasound-assisted SDS washing as the most attractive option, offering the best balance between deodorization efficiency, process simplicity, and cost. Overall, the results provide a practical basis for selecting scalable decontamination strategies to upgrade rHDPE quality and expand its use in circular plastic applications. Full article

Serverless computing has emerged as a prominent research focus in cloud computing because it provides infrastructure-transparent development and elastic resource management. However, this computing paradigm still faces the inherent challenge of cold start. Existing approaches have two major limitations: insufficient workload prediction accuracy and inefficient allocation of reusable container replicas to incoming function requests. To address these challenges, we propose a container scheduling approach based on Workload Prediction and Particle Swarm Optimization (PSO), named WPPSO. WPPSO first leverages a code-pre-trained large language model (LLM) to extract intrinsic function features and then uses a spatio-temporal fusion-based temporal neural network (STF-TNN) to predict serverless workloads. It subsequently employs a greedy algorithm to construct a high-quality initial matching state and uses PSO to refine the container scheduling strategy. Finally, WPPSO introduces a hierarchical container recycling mechanism to reduce idle resource waste. Extensive experiments show that WPPSO reduces startup latency by up to 72.2% and memory footprint by 63.4% compared with the native Knative platform. Compared with RainbowCake, WPPSO achieves a 15.6% lower mean startup latency without statistical significance and a statistically significant 31% reduction in idle memory consumption. Full article

Circular agriculture has emerged as a promising framework for addressing the inefficiencies and environmental pressures associated with conventional food production systems. Within this context, livestock systems can play a transformative role by enabling waste valorisation, enhancing nutrient recycling, and improving overall resource-use efficiency. This review critically examines the multifunctional role of livestock in circular agriculture, with a particular focus on their capacity to convert non-human-edible biomass, such as crop residues, agro-industrial by-products, and food waste, into high-value animal-sourced foods. Drawing on the recent literature, the analysis explores how livestock systems can be reconfigured to utilise non-human-edible biomass, including crop residues, agro-industrial by-products, and food waste, thereby reducing competition between feed and food while enhancing sustainability outcomes. The findings highlight that livestock can function as biological upcycles, converting low-value materials into high-quality animal products, while also contributing to closed nutrient loops through manure management and integration with crop production. Additional benefits include the generation of renewable energy through anaerobic digestion and improved economic resilience through diversified outputs. However, the extent of these benefits depends on system design, management practices, and regional context. Despite their potential, circular livestock systems face challenges related to greenhouse gas emissions, regulatory constraints, economic feasibility, and knowledge gaps. These challenges highlight the need for a systems-based evaluation that accounts for environmental, economic, and social dimensions. The study concludes that livestock can contribute meaningfully to sustainable food system transitions when aligned with circular principles, but their role must be critically assessed to avoid burden-shifting and unintended environmental impacts. Full article