Search Results (3,543)

Recycling water offers a powerful way to lower the environmental water impact of mining activities. Pressure-retarded osmosis (PRO) represents a promising pathway for simultaneous water reuse and clean energy generation from salinity gradients. In this study, the performance of a thin-film nanocomposite (TFN) membrane containing functionalized multi-walled carbon nanotubes (fMWCNTs) within a polyacrylonitrile (PAN) support layer, followed by polydopamine (PDA) surface modification, was investigated under a PRO operation using pretreated gold mining wastewater as the feed solution. Unlike most previous studies that rely on synthetic feeds, this work evaluates the membrane performance under a PRO operation using a real mining wastewater stream. The membrane with fMWCNTs and PDA exhibited a maximum power density of 25.22 W/m² at 12 bar, representing performance improvements of 23% and 68% compared with the pristine thin-film composite (TFC) and commercial cellulose triacetate (CTA) membranes, respectively. A high water flux of 75.6 L·m⁻²·h⁻¹ was also obtained, attributed to enhanced membrane hydrophilicity and reduced internal concentration polarization. The optimized membrane, containing 0.3 wt% fMWCNTs in the support layer and a PDA coating on the active layer, produced a synergistic enhancement in the PRO performance, resulting in a lower reverse salt flux and an improved flux–selectivity trade-off. Furthermore, the ultrafiltration (UF) and nanofiltration (NF) pretreatment effectively reduced the hardness and ionic content, enabling a stable PRO operation with real mining wastewater over a longer period of time. Overall, this study demonstrates the feasibility of achieving both reusable water and enhanced osmotic power generation using modified TFN membranes under realistic mining wastewater conditions. Full article

This study evaluated the feasibility of using recycled plastics (PP, HDPE, and PET) for sustainable construction applications. Materials were collected, processed, and extruded following a structured methodology, and their physico-mechanical and environmental properties were assessed through standardized tests, including compression, flexural strength, water absorption, porosity, and apparent density. Compression tests showed that increasing the processing temperature led to a reduction in the compressive strength of polypropylene (PP), while high-density polyethylene (HDPE) achieved its highest strength at the lowest temperature. Polyethylene terephthalate (PET) exhibited a similar decreasing trend with temperature. The processing speed, expressed as revolutions per minute (rpm), had little influence on PP and HDPE performance but positively affected PET, where higher rpm consistently improved compressive strength. Flexural tests revealed that higher rpm values enhanced the mechanical performance of PP and HDPE. However, for PP, an increase in processing temperature resulted in a pronounced decline in flexural strength. Overall, PP and HDPE outperformed PET, reaching compressive strengths near 10 MPa compared to values below 4 MPa for PET. In flexural tests, PP achieved 44 MPa, followed by HDPE with 25 MPa. Water absorption remained below 1% for all materials. The study is limited to physico-mechanical characterization and does not include microstructural or thermal analyses to assess crystallinity, degradation, or molecular orientation. Future research will focus on advanced thermal–chemical characterization and process optimization—particularly for PET—to improve ductility and expand the applicability of recycled plastics in construction. Full article

Recycled wastewater is vital for the circular economy, especially on water-scarce islands. This study explored the presence of Carbapenem-Resistant Enterobacterales and other emerging pathogens in irrigation water on four Canarian Islands, applying a One Health perspective. Using membrane filtration and MALDI-TOF mass spectrometry, 69 bacterial isolates were identified. The findings revealed that 78% were Gram-negative bacilli like Pseudomonas aeruginosa, Acinetobacter spp., Enterobacteriaceae, etc., while 22% were Gram-positive bacteria, including Enterococcus spp. The main mechanisms of carbapenem resistance in Pseudomonas spp. and Acinetobacter spp. were oxacillinases, followed by metallo-β-lactamases (MBL). In Enterobacteriaceae, characterization of carbapenemase types was less frequent, with oxacillinase 48 (OXA-48) being the most prevalent. The detection of multidrug-resistant organisms in recycled wastewater highlights an urgent need for routine microbiological monitoring in water management to protect both public health and agricultural sustainability. Full article

This review synthesizes the literature on the degradation and decomposition of holopelagic Sargassum, with a focus on process dynamics, including microbial contribution, process descriptions, and ecological impacts. Our objective is to consolidate a robust knowledge framework to inform and optimize management strategies in affected areas. Overall, we observed that the current literature relies primarily on isolated field ecological descriptions rather than a coherent, unified research line; mechanistic studies, including bacterial pathways and factors controlling degradation, remain scarce. At the fine scale, microbial community shifts during decomposition are strongly linked to the sequential utilization of distinct organic substrates, thereby favoring the proliferation of microorganisms capable of degrading complex organic molecules and of bacterial groups involved in sulfur respiration, methanogenesis, and nutrient recycling. In the case of sulfur respiration, groups such as Desulfobacterales and Desulfovibrionales may be responsible for the reported H₂S emissions, which pose significant public health concerns. At a broad scale, degradation occurs both on beaches during emersion and in the water column during immersion, particularly during massive accumulations. The initial stages are characterized by the release of organic exudates and leachates. Experimental and observational studies confirm a strong early-stage release of H₂S until the substrate is largely depleted. Depending on environmental conditions, a significant amount of biomass can be lost; however, this loss is highly variable, with notable consequences for contamination studies. Leachates may also contain low but ecologically significant amounts of arsenic, posing a potential contamination risk. Decomposition contributes to water-quality deterioration and oxygen depletion, with impacts at the individual, population, and ecosystem levels, yet many remain imprecisely attributed. Although evidence of nutrient enrichment in the water column is limited, studies indicate biological nutrient uptake. Achieving a comprehensive understanding of degradation and decomposition, including temporal and spatial dynamics, microbiome interactions, by means of directed research, is critical for effective coastal management, improved mitigation strategies, industrial valorization, and accurate modeling of biogeochemical cycles. Full article

This research examines the feasibility of recovering and recycling condensate water, a waste byproduct generated by Atlas Copco ZR315 FF industrial air compressors utilizing oil-free rotary screw technology with integrated dryers. Given the growing severity of global water scarcity, finding alternative water sources is essential for sustainable industrial practices. This study specifically evaluates the potential of capturing and treating compressed air condensate as a viable method for water recovery. The investigation analyzes both the quantity and quality of condensate water produced by the ZR315 FF unit. It contrasts this recovery approach with traditional water production methods, such as desalination and atmospheric water generation (AWG) via dehumidification. The findings demonstrate that recovering condensate water from industrial air compressors is a cost-effective and energy-efficient substitute for conventional water production, especially in water-stressed areas like Morocco. The results show a significant opportunity to reduce industrial water usage and provide a sustainable source of process water. This research therefore supports the application of circular economy principles in industrial water management and offers practical solutions for overcoming water scarcity challenges within manufacturing environments. Full article

The construction industry consumes a substantial amount of resources. The associated environmental degradation and accelerating biodiversity loss highlight the urgent need for sustainable building materials that can match the performance of conventional alternatives. The objective of this experimental study was to investigate a fully reused, binder-free earth-based material that remains recyclable after its useful life. The material consists of smectite-rich excavation earth and processed demolition waste in a 2:1 ratio, which was compacted under high pressures and subsequently tested to evaluate its mechanical properties. Cylindrical specimens were fabricated via double-ended uniaxial compaction at pressures ranging from 12.5 to 100 MPa and consolidation times between 1 s and 30 min. They were then tested for their compressive strength and water durability. The findings indicate a strong positive correlation between compaction pressure, density, and compressive strength. A compressive strength of 19.2 MPa was reached by specimens that were compacted at 100 MPa for 30 min, achieving values comparable to standard C20/25 concrete. Despite an increase in strength, water durability decreased with increasing compaction pressure but improved with higher molding water content, possibly due to changes in the microstructure. The findings confirm that compressed earth can reach similar compressive strength to conventional materials with a significantly smaller ecological footprint. Full article

To enhance the ductility of coal mine filling materials using recycled asphalt pavement (RAP) and address the limitations in RAP recycling and utilization, this study processed RAP into crushed materials (CMs) and ball-milled materials (BMs). Supplementary with fly ash (FA) and cement, RAP-fly ash cement paste backfill (RFCPB) was prepared. For 1000 g of RFCPB slurry, the composition was 365 g CM, 73 g cement, 270 g water, and a total of 292 g of FA and BM, with an F/B ratio ranging from 1:7 to 7:1. A systematic test program was carried out, including rheological property tests, unconfined compressive strength (UCS) tests combined with deformation monitoring, microstructure analysis, and leaching toxicity tests. Based on these tests, the influence of F/B ratio on the action mechanism, workability, mechanical properties, ductility and environmental compatibility of RFCPB was comprehensively explored. The results show that the rheological behavior of RFCPB slurry conforms to the Herschel–Bulkley (H-B) model; with the decrease in F/B ratio, the yield stress and apparent viscosity of the slurry increase significantly, while the slump and slump flow decrease correspondingly, which is closely related to the particle gradation optimization by BM. For mechanical properties and ductility, the 28-day UCS of RFCPB first increases and then decreases with the decrease in F/B ratio, all meeting the mine backfilling strength requirements; notably, the increase in BM proportion regulates the failure mode from brittle to ductile, which is the key to improving ductility. Microstructural analysis indicates that Dolomite and Albite in BM participate in hydration reactions to generate N-A-S-H and C-A-S-H gels, which fill internal pores, optimize pore structure, and thus synergistically improve UCS and ductility. Additionally, the leaching concentration of toxic ions in RFCPB complies with the environmental protection standards for solid waste. This study provides a theoretical basis for enhancing backfill ductility and advancing the coordinated disposal of RAP and fly ash solid wastes. Full article

A treatment process was developed for effluents from direct physical lithium-ion battery (LIB) recycling with a focus on the removal of organic contaminants. The high chemical oxygen demand to biological oxygen demand ratio (COD/BOD₅) of 3.9–4.6 indicates that biological treatment is not feasible. Therefore, three advanced oxidation processes were evaluated: UV/H₂O₂ oxidation, the Fenton process and electrochemical oxidation. Two target scenarios were considered, namely compliance with the limit for discharge into the sewer system (COD = 800 mg/L) and compliance with the stricter limit for direct discharge into surface waters (COD = 200 mg/L). Under the investigated conditions, UV/H₂O₂ oxidation and the Fenton process did not meet the required discharge limits and exhibited high chemical consumption. In contrast, electrochemical oxidation achieved both discharge criteria with a lower energy demand, requiring 32.8 kWh/kgCOD_removed for sewer discharge and 95.3 kWh/kgCOD_removed for direct discharge. An economic assessment further identified electrochemical oxidation as the most cost-effective option, with treatment costs of EUR 6.63/m³, compared to EUR 17.31/m³ for UV/H₂O₂ oxidation and EUR 28.66/m³ for the Fenton process. Overall, electrochemical oxidation proved to be the most efficient and environmentally favorable technology for treating wastewater from LIB recycling, enabling compliance with strict discharge regulations while minimizing the chemical and energy demand. Full article

Liquefaction in urban areas has repeatedly caused severe damage to infrastructure, including manhole uplift, road subsidence, and failure of buried utility lines, as evidenced by reports during major earthquakes such as the 1964 Niigata earthquake and the 2011 Great East Japan Earthquake. Although natural sand has been widely used as backfill, excess pore water pressure leads to rapid loosening. This study evaluates slag–dried sludge mixed soil as a new liquefaction-resistant backfill that improves disaster mitigation while promoting resource recycling. Compaction, cone penetration, and shaking table tests were conducted with sludge mixing ratios of 0–30%, identifying 20% as optimal. Liquefaction in slag-only soil occurred at 1013 s (7 m/s²), whereas the 20% mixture delayed it to 1380 s (11 m/s²), increasing the acceleration threshold by 1.5 times and extending the onset time by 36%. Therefore, the acceleration required for liquefaction to begin was approximately 1.5 times higher, and the occurrence time was extended by approximately 36%. Also, the cone index reached 7750 kPa, exceeding the traffic load requirement of 1200 kN/m², while still allowing for sufficient permeability and workability compared to the use of natural clay particles. The improved backfill material proposed is promising as a sustainable urban infrastructure technology that simultaneously reduces liquefaction damage, improves the resilience of urban infrastructure, and reduces environmental impact through waste recycling. Full article

Aluminothermic reduction is gaining renewed interest as an alternative processing route for the circular economy. A unique Na₂O-fluxed MnO₂ ore formulation with a small quantity of carbon reductant was applied to ensure rapid pre-reduction to MnO. This approach negates the pre-roasting step. The Na₂O flux enables the formation of the water-soluble compound, NaAlO₂, which enables recycling of Al₂O₃ for aluminium production. The addition of copper as a collector metal improved the overall alloy yield from 43% to 57%, which includes a 6% increase in Mn recovery to the alloy. The product alloy is a medium-carbon Fe–Mn–Si–Al–Cu complex ferroalloy that can be used as a steelmaking ferroalloy additive. The ferroalloy consists of 54% Mn, 19% Fe, 2.1% Si, 2.6% Al, 21% Cu, and 1.2% C. This carbon content is modulated by low-carbon solubility copper, despite the use of a graphite crucible. The formulated slag exhibits high Al₂O₃ solubility, enabling effective alloy–slag separation from the high Al₂O₃ content slag of 52% Al₂O₃. Gas–slag–metal equilibrium calculations for 1650 °C–1950 °C overlap with the experimentally produced alloy chemistry in %C and %Si, but not the %Al, as the uptake of aluminium exceeds the equilibrium calculation at 0.03–0.17%. Full article

To address the low-value recycling dilemma of waste polyvinyl butyral (PVB) and cater to the demand for sustainable multifunctional active food packaging, this study developed a facile and cost-effective solution blow spinning approach. Continuous, smooth, and bead-free nanofiber membranes were prepared by optimizing the solution blow spinning process parameters. Zinc oxide nanoparticles (ZnO NPs) were incorporated into the PVB nanofiber membrane with vacuum impregnation. The results demonstrated that ZnO NPs significantly enhanced the tensile strength, thermal stability, and the UV absorption of PVB fiber membranes. ZnO/PVB fiber membranes exhibited antibacterial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Practical preservation tests showed that ZnO/PVB fiber membranes effectively inhibited cherry tomatoes’ microbial spoilage and water loss, extending the shelf life of tomatoes to 13 days. These findings validate the potential of ZnO/PVB composite nanofiber membranes as active food packaging and provide a feasible technical pathway for the low-cost, efficient utilization of recycled PVB. Full article

The escalating global water crisis demands the development of cost-effective and environmentally sustainable treatment technologies. Among various advanced oxidation processes (AOPs), peracetic acid (PAA) has emerged as a promising oxidant, owing to its high redox potential, chemical stability, and potent disinfection capability. Nevertheless, the lack of highly efficient catalysts remains a major obstacle to achieving the effective degradation of contaminants of emerging concern in wastewater. Heterogeneous catalysis has proven to be a viable strategy for enhancing PAA activation, highlighting the urgent need for catalysts with superior activity, stability, and recyclability. Metal–organic frameworks (MOFs), with their large surface areas, tunable porosity, and structural diversity, provide versatile platforms for catalyst design. Recently, MOF-derived materials have attracted increasing attention for PAA activation, offering a new frontier in advanced oxidation technologies for efficient and sustainable wastewater remediation. This review systematically examines the role of MOFs in PAA activation, from pristine frameworks to MOF-based composites and MOF-derived catalysts. Mechanistic insights into PAA activation are highlighted, strategies for engineering MOF-based composites with synergistic catalytic properties are discussed, and the transformation of MOFs into robust derivatives with improved stability and reactivity is explored. Special attention is given to the identification and quantification of reactive species generated in PAA systems, providing a critical understanding of reaction pathways and catalytic performance. Finally, current challenges and future directions are outlined for designing highly efficient, recyclable, and environmentally compatible MOF-based catalysts, emphasizing their potential to significantly advance PAA-based AOPs. Full article

Froth flotation is a widely used method for the selective separation of particulates from aqueous dispersions or slurries. This technology is based on the attachment of sufficiently hydrophobic particles to the air–water interface of gas bubbles. However, when the target particles are strongly hydrophilic, the requirement of hydrophobicity limits the effectiveness of conventional froth flotation. A prominent example is the deinking step in paper recycling, where modern hydrophilic inkjet inks are difficult to remove by flotation. In this study, we evaluated oil-coated bubble flotation as an alternative to conventional air flotation for removing inkjet ink from pulped newsprint. We examined the effects of oil type, salt type and concentration, and pH on deinking efficiency. Compared with traditional air flotation, oil-coated bubble flotation produced substantial improvements in standard performance metrics, including ISO brightness, effective residual ink concentration (ERIC), and the fiber retention of recycled paper pads. Full article

This study investigated the efficacy of electrochemical treatment of a water-soluble cutting fluid (SCF) solution using Al, Fe, and stainless steel (SUS304) scraps as three-dimensional (3D) electrode packing materials. The SCF solution had an initial COD_Cr of approximately 109,000 mg·L⁻¹, a TOC of approximately 25,000 mg·L⁻¹, and an initial pH of 9.65. During treatment, the pH remained in the alkaline range (9.99–10.67), and the solution conductivity was approximately 1000 μS·cm⁻¹. Using a conventional two-dimensional (2D) configuration, Al exhibited the highest removal efficiencies (TOC: 58.55%; COD_Cr: 57.12%). An applied current of 0.8 A, corresponding to a current density of 5.00 mA·cm⁻² based on the geometric electrode area, and an inter-electrode distance of 40 mm provided an optimal balance between treatment performance and energy consumption. Under these optimized conditions, the introduction of metal scraps as 3D packing media significantly enhanced treatment efficiency. Al scrap (20 g) achieved the highest TOC removal (69.55%), while Fe scrap showed superior COD_Cr removal (87.42% at 40 g) with the lowest specific energy consumption (0.27 kWh·kg⁻¹ COD_removed). The energy consumption of the baseline D system was 0.46 kWh·kg⁻¹ COD_removed(cage O) and 0.72 kWh·kg⁻¹ COD_removed(cage X). Overall, scrap-based 3D electrodes effectively improved organic removal and energy performance, demonstrating their potential as low-cost and sustainable electrode materials for the electrochemical pre-treatment of high-strength oily wastewater. Full article

This study investigates a metakaolin-based geopolymer matrix in which two types of non-recyclable mirror glass waste (MGW) were used as alternative aggregates. The composition, properties and contents of MGW materials as well as their impact on the structure and performance of the geopolymer composites (MGW-Gs) have been characterized using X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG), and Fourier transform infrared spectroscopy (FTIR). Mechanical properties, porosity and thermal conductivity have been evaluated, and compared with silica sand reference composites. The results show that MGW-based composites achieved flexural strengths of 3.9–5.7 MPa and compressive strengths of 60–70 MPa, which are lower than those of sand-based materials (8–11 MPa and up to 93.5 MPa, respectively) but remain adequate performance for applications with moderate load. FTIR analysis has indicated that the incorporation of MGW does not adversely affect the geopolymer network. All composites display similar porosity (approximately 18–22%) and water absorption (12–14%), while MGW incorporation has improved their thermal stability and significantly reduced their thermal conductivity to values below 0.53 W·m⁻¹·K⁻¹, compared with up to 1.09 W·m⁻¹·K⁻¹ for sand-based composites, emphasizing their insulation potential and sustainability benefits. The findings indicate that MGW aggregates can influence the microstructure, mechanical performance, and thermal properties of geopolymer composites, suggesting their potential use in specific construction applications. Full article