Search Results (296)

Though the pursuit of sustainable desalination processes with high water recovery has intensified the research interest in membrane distillation (MD), the influence of module connection configuration on performance stability remains poorly explored. The current study provided a comprehensive multiparameter assessment of hollow fibre membrane modules connected in parallel and series in direct contact membrane distillation (DCMD) for the first time. The configurations were evaluated under varying process parameters such as temperature (50–70 °C), flow rates (22.1–32.3 mL·s⁻¹), magnesium concentration as scalant (1.0–4.0 g·L⁻¹), and flow direction (co-current and counter-current), assessing their influence on temperature gradients (∆T), flux and pH stability, salt rejection, and crystallisation. Interestingly, the parallel module configuration maintained high operational stability with uniform flux and temperature differences (∆T) even at high recovery factors (>75%). On one hand, the serial configuration experienced fluctuating ∆T caused by thermal and concentration polarisation, causing an early crystallisation (abrupt drop in feed conductivity). Intensified polarisation effects with accelerated crystallisation increased the membrane risk of wetting, particularly at high recovery factors. Despite these changes, the salt rejection remained relatively high (99.9%) for both configurations across all tested conditions. The findings revealed that acidification trends caused by MgSO₄ were configuration-dependent, where the parallel setup-controlled rate of pH collapse. This study presented a novel framework connecting membrane module architecture to mass and heat transfer phenomena, providing a transformative DCMD module configuration design in water desalination. These findings not only provide the critical knowledge gaps in DCMD module configurations but also inform optimisation of MD water desalination to achieve high recovery and stable operation conditions under realistic brine composition. Full article

Cassava is the sixth most important food crop and is cultivated in more than 100 countries. The crop tolerates low soil fertility and drought, enabling it to play a role in climate adaptation strategies. Cassava generally requires careful preparation to remove toxic hydrogen cyanide (HCN) before its consumption, but HCN concentrations can vary considerably between varieties. Climate change and low inputs, particularly carbon and nutrients, affect agriculture in Pacific Island countries where cassava is commonly grown alongside traditional crops (e.g., taro). Despite increasing popularity in this region, there is limited experimental data about cassava crop management for different local varieties, their relative toxicity and nutritional value for human consumption, and their interaction with changing climate conditions. To help address this knowledge gap, three field experiments were conducted at the Koronivia Research Station of the Fiji Ministry of Agriculture. Two varieties of cassava with contrasting HCN content were planted at three different times coinciding with the start of the wet (September-October) or dry (April) seasons. A time series of measurements was conducted during the full 18-month or differing 6-month durations of each crop, based on destructive harvests and phenological observations. The former included determination of total biomass, HCN potential, carbon isotopes (δ¹³C), and elemental composition. Yield and nutritional value were significantly affected by variety and time of planting, and there were interactions between the two factors. Findings from this work will improve cassava management locally and will provide a valuable dataset for agronomic and biophysical model testing. Full article

Groundwater systems are intrinsically linked to climate, with changing conditions significantly altering recharge, storage, and discharge processes, thereby impacting water availability and ecosystem integrity. Critical knowledge gaps persist regarding groundwater equilibrium timescales, water table dynamics, and their governing factors. This study develops a novel remote sensing framework to quantify factor controls on groundwater–climate interaction characteristics in the Heihe River Basin (HRB). High-resolution (0.005° × 0.005°) maps of groundwater response time (GRT) and water table ratio (WTR) were generated using multi-source geospatial data. Employing Geographical Convergent Cross Mapping (GCCM), we established causal relationships between GRT/WTR and their drivers, identifying key influences on groundwater dynamics. Generalized Additive Models (GAM) further quantified the relative contributions of climatic (precipitation, temperature), topographic (DEM, TWI), geologic (hydraulic conductivity, porosity, vadose zone thickness), and vegetative (NDVI, root depth, soil water) factors to GRT/WTR variability. Results indicate an average GRT of ~6.5 × 10⁸ years, with 7.36% of HRB exhibiting sub-century response times and 85.23% exceeding 1000 years. Recharge control dominates shrublands, wetlands, and croplands (WTR < 1), while topography control prevails in forests and barelands (WTR > 1). Key factors collectively explain 86.7% (GRT) and 75.9% (WTR) of observed variance, with spatial GRT variability driven primarily by hydraulic conductivity (34.3%), vadose zone thickness (13.5%), and precipitation (10.8%), while WTR variation is controlled by vadose zone thickness (19.2%), topographic wetness index (16.0%), and temperature (9.6%). These findings provide a scientifically rigorous basis for prioritizing groundwater conservation zones and designing climate-resilient water management policies in arid endorheic basins, with our high-resolution causal attribution framework offering transferable methodologies for global groundwater vulnerability assessments. Full article

The dynamic non-equilibrium effect (DNE) describes the non-unique character of saturation–capillary pressure relationships observed under static, steady-state, or monotonic hydrodynamic conditions. Macroscopically, the DNE manifests as variations in soil hydraulic characteristic curves arising from varying hydrodynamic testing conditions and is fundamentally governed by soil matrix particle size distribution. Changes in the DNE across porous media with discrete particle size fractions are investigated via stepwise drying experiments. Through quantification of saturation–capillary pressure hysteresis and DNE metrics, three critical signatures are identified: (1) the temporal lag between peak capillary pressure and minimum water saturation; (2) the pressure gap between transient and equilibrium states; and (3) residual water saturation. In the four experimental sets, with the finest material (Test 1), the peak capillary pressure consistently precedes the minimum water saturation by up to 60 s. Conversely, with the coarsest material (Test 4), peak capillary pressure does not consistently precede minimum saturation, with a maximum lag of only 30 s. The pressure gap between transient and equilibrium states reached 14.04 cm H₂O in the finest sand, compared to only 2.65 cm H₂O in the coarsest sand. Simultaneously, residual water saturation was significantly higher in the finest sand (0.364) than in the coarsest sand (0.086). The results further reveal that the intensity of the DNE scales inversely with particle size and linearly with wetting phase saturation (Sw), exhibiting systematic decay as Sw decreases. Coarse media exhibit negligible hysteresis due to suppressed capillary retention; this is in stark contrast with fine sands, in which the DNE is observed to persist in advanced drying stages. These results establish pore geometry and capillary dominance as fundamental factors controlling non-equilibrium fluid dynamics, providing a mechanistic framework for the refinement of multi-phase flow models in heterogeneous porous systems. Full article

Janus nanoparticles (JNPs) extend the concept of amphiphilicity beyond classical molecular surfactants into the nanoscale. Amphiphilic behavior is defined by the presence of hydrophobic and hydrophilic moieties within a single molecular structure. Traditionally, such molecular structures are known as surfactants or amphiphiles and are capable of reducing interfacial tension, adsorbing spontaneously at interfaces, stabilizing emulsions and foams, and forming micelles, bilayers, or vesicles. Recent experimental, theoretical, and computational studies demonstrate that these behaviors are scalable to nanostructured colloids such as JNPs. Amphiphilic JNPs, defined by anisotropic surface chemistry on distinct hemispheres, display interfacial activity driven by directional wetting, variable interfacial immersion depth, and strong interfacial anchoring. They can stabilize liquid/liquid and liquid/gas interfaces, and enable templated or spontaneous self-assembly into supra-structures, such as monolayer sheets, vesicles, capsules, etc., both in bulk and at interfaces. Their behavior mimics the “soft” molecular amphiphiles but also includes additional particularities given by their “hard” structure, as well as contributions from capillary, van der Waals, hydrophobic, and shape-dependent forces. This review focuses on compiling the evidence supporting amphiphilicity as a scalable property, discussing how JNPs function as colloidal amphiphiles and how geometry, polarity contrast, interfacial interactions, and environmental parameters influence their behavior. By comparing surfactant behavior and JNP assembly, this work aims to clarify the transferable principles, the knowledge gap, as well as the emergent properties associated with amphiphilic Janus colloids. Full article

Municipal sewage sludge, a by-product of urban wastewater treatment, is increasingly recognized to be a strategic resource rather than a disposal burden. Traditional management practices, such as landfilling, incineration, and land application, are facing growing limitations due to environmental risks, regulatory pressures, and the underuse of the sludge’s energy and nutrient potential. This review examines the evolution of sludge management, focusing on technologies that enable energy recovery and resource valorization. The transition from linear treatment systems toward integrated biorefineries is underway, combining biological, thermal, and chemical processes. Anaerobic digestion remains the most widely used energy-positive method, but it is significantly improved by processes such as thermal hydrolysis, hydrothermal carbonization, and wet oxidation. Among these, hydrothermal carbonization stands out for its scalability, energy efficiency, and phosphorus-rich hydrochar production, although implementation barriers remain. Economic feasibility is highly context-dependent, being shaped by capital costs, energy prices, product markets, and policy incentives. This review identifies key gaps, including the need for standardized treatment models, decentralized processing hubs, and safe residual management. Supportive regulation and economic instruments will be essential to facilitate widespread adoption. In conclusion, sustainable sludge management depends on modular, integrated systems that recover energy and nutrients while meeting environmental standards. A coordinated approach across technology, policy, and economics is vital to unlock the full value of this critical waste stream. Full article

Rivers are recognized as significant pathways and transportation for microplastics (MPs), an emerging contaminant, to aquatic environments. However, there is limited evidence on how riverine reservoirs influence MPs transport. To fill this gap and provide baseline empirical data and insights to South African context, the current study assessed the seasonal variation in MP densities from sediments collected upstream, within the reservoir, and downstream of the Vondo Reservoir along the Mutshindudi River. We hypothesised that MP densities would be highest within the reservoir, due to the lack of constant flow that would otherwise transport accumulated particles downriver. Additionally, we expected the cool–dry season to be associated with the highest MP densities. As expected, high MP densities were observed within the reservoir (117.38–277.46 particles kg⁻¹ dwt) when compared to the downstream (72.63–141.50 particles kg⁻¹ dwt) and upstream (28.81–91.63 particles kg⁻¹ dwt) sites of the reservoir. The cool–dry season (91.63–277.46 particles kg⁻¹ dwt) exhibited the highest MP densities compared to the hot–wet season (28.81–141.50 particles kg⁻¹ dwt). However, MP densities downstream the reservoir were higher during the hot–wet season (141.50 ± 24.34 particles kg⁻¹ dwt) compared to the cool–dry season (72.63 ± 48.85 particles kg⁻¹ dwt). The most dominant MP particles identified were white, transparent, and black fibres/filaments composed primarily of polypropylene (PP) and polyethylene (PE). This suggests diverse sources of MP particles. No significant correlations were found between water parameters and MP densities across sampling sites and seasons, indicating a widespread and context-independent presence of MPs. These findings contribute to MP studies in freshwater environments and further reinforce the role of sediments as sink for MPs and suggest that riverine reservoirs similar to dams can trap MPs, which may then be remobilized downstream during high-flow periods. Importantly, the results of this study can support local municipalities in implementing targeted plastic pollution mitigation strategies and public awareness campaigns, particularly because the Vondo Reservoir serves as a critical water resource for surrounding communities. Full article

Wet multi-disc clutches in transmission systems suffer from the incomplete separation of the friction components, which raises the drag torque and results in power loss and heightened fuel consumption. This incomplete separation arises from the force imbalance between resistance forces, such as the oil viscosity force, and the lack of an axial separating force. Therefore, providing an axial separating force is a potential solution to this problem. In this investigation, small-angle conical separate plates were designed which can provide the elastic restoring force during the separation process. Based on its structural properties, a model describing the clutch engagement and separation process was established. Through bench tests, the feasibility of the model was verified. The influence of the conical plate on the dynamics of the clutch was studied, including the influence of the separation gap, uniformity, and drag torque. Though the transmitted torque was reduced by 10.31% in the low-piston-pressure condition and by less than 2% in the high-piston-pressure condition, the problem of incomplete separation was successfully resolved. The results show that when applying the conical plates, the separation time was reduced by 18.78%, with a 25.31% increase in the uniformity of the gaps. Accordingly, the drag torque was reduced by 37.73%. Full article

Fire-driven land cover change has generated a paradox: while habitat fragmentation from agriculture, livestock, and urban expansion has reduced natural fire occurrences, human-induced ignitions have increased wildfire frequency and intensity. In northern Colombia’s Magdalena Department, most of the territory faces moderate to high wildfire risk, especially during recurrent dry seasons and periods of below-average precipitation. However, knowledge of wildfire spatiotemporal occurrence and its drivers remains scarce. This work addresses this gap by identifying fire-prone zones and analyzing the influence of climate and vegetation in the Magdalena Department. Fire-prone zones were identified using the Getis–Ord Gi* method over fire density and burned area data from 2001 to 2023; then, they were analyzed with seasonally aggregated hydroclimatic indices via logistic regression to quantify their influence on wildfires. Vegetation susceptibility was assessed using geostatistics, obtaining land cover types most affected by fire and their degree of fragmentation. Fire-prone zones in the Magdalena Department covered ~744.35 km² (3.21%), with a weak but significant (τ = 0.20, p < 0.01) degree of coincidence between classification based on fire density, as pre-fire variable, and burned area, as a post-fire variable. Temporally, fire probability increased during the dry season, driven by short-lagged precursors such as Dry Spell Length and precipitation from the preceding wet season. Fire-prone zones were dominated by pastures (62.39%), grasslands and shrublands (19.61%) and forests (15.74%), and exhibited larger, more complex high-risk patches, despite similar spatial connectedness with non-fire-prone zones. These findings enhance wildfire vulnerability understanding, contributing to risk-based territorial planning. Full article

Unfired bricks offer a sustainable alternative to traditional fired bricks by enabling the large-scale reuse of industrial, construction, and municipal wastes while significantly reducing energy consumption and greenhouse gas emissions. This review contributes to eliminating knowledge fragmentation by systematically organising stabiliser technologies, performance metrics, and sustainability indicators across a wide variety of unfired brick systems. It thus provides a coherent reference framework to support further development and industrial translation. Emphasis is placed on the role of stabilisers—including cement, lime, geopolymers, and microbial or bio-based stabilisers—in improving mechanical strength, moisture resistance, and durability. Performance data are analysed in relation to compressive strength, water absorption, drying shrinkage, thermal conductivity, and resistance to freeze–thaw and wet–dry cycles. The findings indicate that properly stabilised unfired bricks can achieve compressive strengths above 20 MPa and water absorption rates below 10%, with notable improvements in insulation and acoustic properties. Additionally, life-cycle comparisons reveal up to 90% reductions in CO₂ emissions and energy use relative to fired clay bricks. Despite technical and environmental advantages, broader adoption remains limited due to standardisation gaps and market unfamiliarity. The paper concludes by highlighting the importance of hybrid stabiliser systems, targeted certification frameworks, and waste valorisation policies to support the transition toward low-carbon, resource-efficient construction practices. Full article

Microplastics (MPs), particularly fibrous MPs, have emerged as a significant environmental concern due to their pervasive presence in aquatic and terrestrial ecosystems. The textile industry is a significant contributor to MP pollution, particularly through the production of synthetic fibers and natural/synthetic blends, which release substantial amounts of fibrous MPs. Among the various types of MPs, fibrous MPs account for approximately 49–70% of the total MP load found in wastewater globally, primarily originating from textile manufacturing processes and the domestic laundering of synthetic fabrics. MP shedding poses a significant challenge for environmental management, requiring a comprehensive examination of the mechanisms and strategies for the mitigation involved. To address the existing knowledge gaps regarding MP shedding during the textile production processes, this brief review examines the current state of MP shedding during textile production, covering both dry and wet processes, and identifies the sources and pathways of MPs from industrial wastewater treatment plants to the environment. It further provides a critical evaluation of the existing recycling and upcycling technologies applicable to MPs, highlighting their current limitations and exploring their potential for future applications. Additionally, it explores the potential for integrating sustainable practices and developing regulatory frameworks to facilitate the transition towards a circular economy within the textile industry. Given the expanding application of textiles across various sectors, including medical, agricultural, and environmental fields, the scope of microplastic pollution extends beyond conventional uses, necessitating urgent attention to the impact of fibrous MP release from both synthetic and bio-based textiles. This brief review consolidates the current knowledge and outlines the critical research gaps to support stakeholders, policymakers, and researchers in formulating effective, science-based strategies for reducing textile-derived microplastic pollution and advancing environmental sustainability. Full article

LED polymer multilayer films offer clear advantages over single-layer coatings, such as minimized particle settling, finer control over particle distribution, and more precise spectral tuning. However, the standard “coat–dry–coat” process for these multilayer systems often traps air bubbles, degrading film quality and uniformity. This study investigates the air entrainment mechanism in multilayer film formation. Bubbles form when the cured bottom layer exhibits a low contact angle, which destabilizes the advancing liquid front. High-speed microscopy captured these interfacial dynamics, and contact-angle measurements quantified the wetting behavior. Numerical simulations further demonstrated that reduced wettability and vortex formation drive air entrainment. To mitigate air entrainment, a semi-cured slot die coating approach was proposed to modify the surface wettability and suppress the flow instabilities. Incorporating temperature-dependent viscosity into the simulation model improved its predictive accuracy, cutting the error in predicted coating-gap limits from 11.49% to 4.99%. This combined strategy delivers reliable, bubble-free multilayer films and paves the way for more consistent, high-quality LED polymer applications. Full article

Microplastics (MPs), defined as plastic particles smaller than 5 mm, are an emerging global environmental and health concern due to their pervasive presence in aquatic ecosystems. This systematic review synthesizes data on the distribution, shapes, materials, and sizes of MPs in various water sources, including lakes, rivers, seas, tap water, and bottled water, between 2014 and 2024. Results reveal that river water constitutes the largest share of studies on MP pollution (30%), followed by lake water (24%), sea water (19%), bottled water (17%), and tap water (11%), reflecting their critical roles in MP transport and accumulation. Seasonal analysis indicates that MP concentrations peak in the wet season (38%), followed by the dry (32%) and transitional (30%) seasons. Spatially, China leads MP research globally (19%), followed by the USA (7.8%) and India (5.9%). MPs are predominantly composed of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), with fibers and fragments being the most common shapes. Sub-millimeter MPs (<1 mm) dominate globally, with significant variations driven by anthropogenic activities, industrial discharge, and environmental factors such as rainfall and temperature. The study highlights critical gaps in understanding the long-term ecological and health impacts of MPs, emphasizing the need for standardized methodologies, improved waste management, and innovative mitigation strategies. This review underscores the urgency of addressing microplastic pollution through global collaboration and stricter regulatory measures. Full article

Wet High-Intensity Magnetic Separators (WHIMSs) have become well established in mineral processing operations by efficiently separating particles based on their magnetic properties. While the existing literature extensively discusses WHIMS performance under varying operational conditions, there is a notable absence of attention to the degradation of coils over time and methods for its detection. In this paper, we address this gap by proposing a novel approach to detect coil degradation in WHIMSs, enabling timely maintenance interventions to maintain optimal performance. Through experimental analysis in an industrial environment, we show the significant effect of coil deterioration on WHIMS efficiency. We also introduce a real-time monitoring method using current measurements in coil sets. This method provides a practical solution for identifying and addressing coil degradation, helping to improve maintenance practices and sustain operational efficiency in mineral processing facilities. The experiments were conducted in a Brazilian iron ore processing company in Itabira, Minas Gerais. Full article

Cities worldwide face significant challenges in managing stormwater, a concern worsened by rapid urbanization and the impacts of climate change. Bioretention landscapes helped solve these issues by replicating natural ecosystems to effectively capture, filter, and treat stormwater while offering additional ecosystem services. However, most studies and existing guides have been for colder and drier climates. Adapting bioretention practices to tropical and wet equatorial climates, characterized by intense rainfall patterns and high temperature and humidity, presents unique challenges and knowledge gaps. This systematic literature review aims to address these gaps by synthesizing existing research from 2010 to 2022 on bioretention landscapes in tropical and wet equatorial climates. Following the methodology outlined in PRISMA guidelines, we identified 10 key studies primarily focusing on countries within the Köppen–Geiger climate zones Aw, Af, and Am, which are tropical and wet equatorial climates. These studies spanned across different continents, including locations such as Malaysia, Singapore, Burkina Faso, and India. Data synthesis revealed critical design elements, including planting selection, substrate layer composition, and performance metrics. Our findings highlight the necessity for climate-specific design approaches and identify key research gaps that can inform future studies and guide practical applications in designing bioretention landscapes for tropical and wet equatorial climates. Full article