Search Results (34)

Plastic waste and industrial residues like steel slag pose significant environmental challenges, with limited recycling solutions. This study investigates a sustainable approach by repurposing waste polystyrene and steel slag into composite membranes via electrospinning for membrane distillation applications. Steel slag incorporation enhanced membrane porosity, hydrophobicity, and thermal stability, with process optimization performed through response surface methodology by varying slag content (0–10 wt%), voltage (15–30 kV), and feed rate (0.18–10 mL·h⁻¹). Optimized membranes achieved a reduced fiber diameter (1.172 µm), high porosity (82.3%), and superior hydrophobicity (contact angle 102.2°). Mechanical performance improved with a 12% increase in tensile strength and a threefold rise in liquid entry pressure over pure polystyrene membranes, indicating greater durability and wetting resistance. In direct contact membrane distillation, water flux improved by 15% while maintaining salt rejection above 98%. Under photothermal membrane distillation, evaporation rates rose by 69% and solar-to-thermal conversion efficiency by 60% compared to standard PVDF membranes. These results demonstrate the feasibility of transforming waste materials into high-performance, durable membranes, offering a scalable and eco-friendly solution for sustainable desalination. Full article

Nowadays, treating residual brine from desalination systems is an important issue for sustainable water management, where Mechanical Vapour Compression (MVC) systems are a great energy-efficient option for small-scale desalination plants. In this paper, an MVC model with TRNSYS 18 software is proposed, validated using real data from an MVC experimental system. A relevant contribution of this paper is that each component of the MVC system is individually modelled considering the challenges faced in the real experimental facility and only using input variables that are managed by real MVC plant operators, achieving accurate output results with the proposed model. Assessment of the model uses real datasets from a real MVC experimental facility in Spain, with more than 30,000 individual real values during validation. As a result, the model generated more than 350,000 values each day used for validation purposes. Comparing output variables, such as distillate production and final salinity, the accuracy of the model achieves a mean absolute error of 6.87% and relative errors lower than $2.90\%$. This contribution highlights the importance of using accurate simulation tools, providing valuable information to optimize MVC systems. Full article

Desalination concentrate (DC) is a residue from desalination plants in semiarid regions, and it is promising for microalgae cultures. Its effects have been evaluated in a previsions study involving Spirulina sp. LEB 18 cultures grown in a medium containing 100% DC, supplemented with 25% Zarrouk nutrients, and without reuse. In the present study, Spirulina sp. LEB 18 was cultivated in the recycled saline concentrate medium from the previous experiment over three consecutive cycles using raceways. The recycled DC achieved a maximum biomass production of 3.77 g·L⁻¹, surpassing the control production (3.45 g·L⁻¹), and demonstrated high resistance to elevated environmental temperatures, reaching 42.80 °C. Protein levels (≤37%) containing all essential amino acids (~40% of total proteins) and fatty acids with relevant impacts on health were reached. Using up to three DC cycles for Spirulina sp. cultivation can contribute to the valorization of this residue and add viability to semiarid regions for biomass production with adequate nutritional composition for supplementation of humans and animals. Full article

The large-scale application of aromatic polyamide (PA) thin-film composite (TFC) membranes for reverse osmosis has provided an effective way to address worldwide water scarcity. However, the water permeability and salt rejection capabilities of the PA membrane remain limited. In this work, cyclic micropores based on crown ether were introduced into the PA layer using a layer-by-layer interfacial polymerization (LbL-IP) method. After interfacial polymerization between m-phenylenediamine (MPD) and trimesoyl chloride (TMC), the di(aminobenzo)-18-crown-6 (DAB18C6) solution in methanol was poured on the membrane to react with the residual TMC. The cyclic micropores of DAB18C6 provided the membrane with rapid water transport channels and improved ion rejection due to its hydrophilicity and size sieving effect. The membranes were characterized by FTIR, XPS, SEM, and AFM. Compared to unmodified membranes, the water contact angle decreased from 54.1° to 31.6° indicating better hydrophilicity. Moreover, the crown ether-modified membrane exhibited both higher permeability and enhanced rejection performance. The permeability of the crown ether-modified membrane was more than ten times higher than unmodified membranes with a rejection above 95% for Na₂SO₄, MgSO₄, MgCl_2, and NaCl solution. These results highlight the potential of this straightforward surface grafting strategy and the modified membranes for advanced water treatment technologies, particularly in addressing seawater desalination challenges. Full article

As a typical phenolic residue and pollutant, 2,4-D wastewater has a complex composition and high salt content, which makes it difficult for a single wastewater treatment method to meet the discharge standard. To address this challenge, this study explores an integrated electrochemical treatment approach that specifically targets 2,4-D high-salt organic wastewater with the aim of achieving the resource utilization of the wastewater and optimizing the operating parameters of each treatment unit. The results show that under the best experimental conditions, the chemical oxygen demand (COD) is significantly reduced to 200 mg/L, and the COD removal efficiency is as high as 99.67%. In addition, the recovery efficiency of phenolic substances 2,4-dichlorophenol, glycolic acid, and sodium chloride in wastewater reached 99.70%, 99.99%, 96.89%, and 80%, respectively. Phenols are used as raw materials for 2,4-D production, glycolic acid is widely used as a cleaning agent in industry, and the purity of recycled sodium chloride is as high as 99.08%, which can be reused as industrial salt. According to the treatment cost estimate, the benefit of recycling can offset the cost of wastewater treatment and may generate a certain economic surplus. This method is of great significance for the treatment of furfural wastewater and the realization of zero discharge of wastewater, which not only contributes to environmental protection but also promotes the sustainable utilization of resources. Full article

The core of saline–alkali soil improvement lies in salt leaching by water and reducing alkalinity by improved materials such as acid material or desulphurized gypsum. This study conducted simulation experiments to clarify the impact of furfural residue combined with desulfurization gypsum on saline–alkali soil water–salt and infiltration characteristics in Ningxia. Based on a consistent leaching water volume of 4500 m³/hm² and a furfural residue application amount of 7.5 t/hm², the experiment established three desulfurization gypsum application amounts of 15 t/hm², 22.5 t/hm², and 30 t/hm², with a control group that received no improved materials. The effects of different application amounts of desulfurization gypsum on water and salt distributions, alkalinity, infiltration rate, cumulative infiltration volume, and wetting front of saline–alkali soil were elucidated, and the Philip infiltration model was employed to fit the variations in cumulative infiltration volume. The results indicated the following: (1) Compared to the control group, the application of furfural residue and desulfurization gypsum resulted in an average reduction of 36.7% in soil alkalinity. The enhanced hydraulic conductivity of saline–alkali soil promoted the infiltration of water into deeper soil layers. The desalination effect in the 0–60 cm soil layer was significant; however, excessive application of desulfurization gypsum could lead to the accumulation of salts in soil layers below 80 cm. (2) The downward movement depth of the wetting front, cumulative infiltration volume, and infiltration rate all demonstrated a power function relationship with the infiltration time, with a coefficient of determination (R²) greater than 0.97. Additionally, the infiltration rate exhibited a linear correlation with the square root of the reciprocal of infiltration time, achieving an R² exceeding 0.99. (3) The Philip infiltration model is suitable for describing the relationship between cumulative infiltration volume and infiltration time. Therefore, the application of 7.5 t/hm² of furfural residue and 22.5 t/hm² of desulfurization gypsum can effectively improve the saline–alkali soils in Ningxia. Full article

Three-dimensional (3D) graphene-based composite materials (3D GBCMs) have emerged as promising candidates for addressing critical challenges in water pollution remediation. This review selectively highlights the recent advancements in the application of 3D GBCMs to remove a wide range of contaminants, including heavy metals, dyes, salts, and pharmaceutical residues, from water. They owe their efficacy to their large surface area, interconnected porous structure, and functionalization potential. Three-dimensional GBCMs are promising materials for water filtration, offering capabilities such as heavy metal ion adsorption, the photocatalytic degradation of organic pollutants, and advanced desalination techniques like capacitive deionization (CDI) and solar desalination, thus providing sustainable solutions for obtaining freshwater from saline sources. Additionally, the factors influencing the pollutant removal capacities of 3D GBCMs, such as their material morphology, particle size, and porosity, are briefly discussed. Notably, the effect of the particle size on pollutant removal has not been extensively studied, and this review addresses that gap by exploring it in detail. Future research directions are also proposed, emphasizing the optimization and broader application of 3D GBCMs in environmental remediation. This review aims to provide valuable insights into the design and practical implementation of 3D GBCMs, offering guidance for their continued development in sustainable water treatment. Full article

Different approaches have been suggested for the waste heat recovery of high-temperature exhausted gas of a solid oxide fuel cell (SOFC). In such systems, mostly gas turbine (GT) and organic Rankine cycle (ORC) are added as bottoming systems to the SOFC (Configuration 1). However, the SOFC-GT-ORC has a considerable amount of waste energy which can be recovered. In the present research, the waste energy of ORC in the heat rejection stage and the residual exhausted gas of the system were recovered by a thermoelectric generator (TEG) and a hot water unit, respectively. Then, the extra produced power in the TEG was directed to a proton exchange membrane electrolyzer and a reverse osmosis desalination unit (RODU) for hydrogen and potable water outputs. The performance of SOFC-GT, Configuration 1, and Configuration 2 was compared through a 4E (energy, exergy, exergy-economic, and environmental) analysis. In the best performance point, the exergy efficiency and unit cost of product (UCOP) of SOFC-GT were obtained as 69.41% and USD 26.53/GJ. The exergy efficiency increased by 2.56% and 2.86%, and the UCOP rose by 0.45% and 12.25% in Configurations 1 and 2. So, the overall performance of Configuration 1 was acceptable and Configuration 2 led to the highest exergy efficiency, while its economic performance was not competitive because of the high investment cost of RODU. Full article

The desalination of aquifers and seawaters is a viable choice to meet primarily domestic and industrial global water requirements. It removes salts from seawater to obtain freshwater with sufficient quality for different purposes, as well as a highly salt-concentrated waste stream known as brine. This residue is usually returned to the ocean, provoking, among other impacts, changes in temperature, salinity and oxygen and overall local aquatic ecosystem stress, as well as social rejection. Desalination in inland aquifers is more complicated because brine disposal is complicated or impossible. The current study presents a new zero-brine discharge technology able to achieve ecological liquid purification through distillation for the separation of the dissolved solids as crystallized salts (Adiabatic Sonic Evaporation and Crystallization, ASE&C). This new technology was used with seawater and three types of brine to test how it would work when coupled with reverse osmosis desalination plants. Analysis of the byproducts after treatment of the seawater and the different brines are presented here. A basic economic approach to calculating potential revenues is also presented. The results of the analyses revealed a complete depuration of water as distilled water, and crystallized solids with highly concentrated commercial salts (with different composition depending on their origin). The estimated economic value of annual revenue (taking into account only seven element recoveries and treatment of a volume of 1000 m³/d) for three types of brines ranged between 1 and 11 million euros, compared to between 3.6 and 9.3 million euros when ASE&C is employed with seawater. The treatment of greater volumes for seawater desalination would increase these numbers significantly. ASE&C supposes a solution coupled (or not) to desalination plants to reduce the ecological impacts associated with brine discharges to zero, obtaining two significant commercial byproducts: (seawater: freshwater and commercial elements Br, Ca, Cs, Cl, NaOH, Mg, N, K, Rb, Na, Sr, Li, U, B, Sr, Ga, etc.; aquifers: a larger list than for saltwater, depending on the nature of the water body). It can solve environmental issues associated with brine discharge, with null CO₂ emissions (renewable energy) and profitable (i.e., with no costly pretreatment) technology. Full article

Membrane distillation (MD) is a thermal desalination technique proposed for the valorization of residual brines that other operations such as reverse osmosis cannot treat. Previous studies have shown that vacuum-assisted air gap (V-AGMD) operation in commercial multi-envelope modules improves the performance of MD noticeably. However, the permeate quality at pilot scale has not been thoroughly characterized so far. The aim of this study is, therefore, to assess and model the effect of the main operating conditions (feed flow rate, inlet temperatures, and feed salinity) on the permeate quality. Results from different steady-state experiments allowed to estimate descriptive metrics such as the salt rejection factor (SRF) and the membrane leak ratio (MLR). Given their non-linear behavior, these metrics were subsequently modeled using artificial neural networks (ANN) to estimate the permeate quality in the whole scope of operating conditions. Acceptable SRF results with MLR values lower than 0.2% confirmed the validity of MD as an operation for the treatment of concentrated brines, although the salinity of the resulting permeate does not comply in all cases with that permitted for human consumption. Full article

Harmful algal blooms (HABs) caused by Heterosigma akashiwo are occurring in coastal waters frequently, posing a great risk to marine environments and subsequent treatment processes like desalination. UV-assisted permanganate oxidation (UV/KMnO₄) is recognized as an innovative advanced oxidation process. This study investigated the inactivation and removal efficiencies of H. akashiwo cells by UV/KMnO₄. Algal cells were effectively disintegrated into fragments by UV/KMnO₄. Also, the degradation of photosynthetic pigments, membrane lipid peroxidation, and severe oxidative stress in algal cells was observed. The removal efficiency of algal cells reached 80.2% by 20 min of UV/KMnO₄ oxidation, with a KMnO₄ dosage of 5 mg L⁻¹. In addition, the residual algal cells could be completely removed by a subsequent self-settling process, without an additional coagulation procedure. The fragmentation of algal cells caused by UV/KMnO₄ may facilitate the formation of algal flocs, thereby improving the cell settleability. Furthermore, UV₂₅₄ was significantly reduced by UV/KMnO₄, which is expected to reduce the formation of disinfection byproducts and membrane fouling. This study elucidates that UV/KMnO₄ can be a promising technique for the efficient treatment of harmful marine algae. Full article

Paddy cultivation in saline soil can rapidly reduce soil salinity, which is an important approach for managing, utilizing, and improving such soils. However, the high salinity of saline soil severely limits the sustainability of paddy production. Adding exogenic organic material to improve soil fertility in saline soil is a key measure for obtaining high-yield, efficient and sustainable cultivation of paddy. This study used a field experiment to explore the influences of different organic materials application on soil desalination and fertility improvement in saline paddy soil. The results showed that the application of dairy manure (DM), sludge vermicompost (SV), and vinegar residue (VR) reduced soil barrier factors, including electrical conductivity (EC) and pH, increased soil fertility, including soil organic carbon (SOC), nitrogen (N), and phosphorus (P), and promoted paddy growth in saline soil. Specifically, soil EC decreased by 29.0%, 32.9% and 49.4% and paddy biomass increased by 27.7%, 63.7% and 107.6% in DM, SV, and VR-treated soils with the highest application rates, respectively, compared to the control. At an equal carbon application rate, VR was more conducive to decreasing soil EC and pH and increasing paddy biomass. Compared to DM and SV, VR addition resulted in an average decrease of 20.7% and 19.1% in soil EC, respectively, and an average increase of 57.3% and 29.5% in paddy biomass. In addition, soil water-stable aggregates (WSA), SOC, N, and P contents in VR-treated soil were lower than those in DM and SV-treated soils. Correlation and path analysis revealed that there was a significant negative correlation between paddy biomass and soil barrier factors. However, EC in VR-treated soil had a direct negative effect on paddy biomass, while EC in DM and SV-treated soils had an indirect negative effect on paddy biomass. Additionally, the direct contribution of soil pH to paddy biomass was higher with VR (−1.49) than that with DM (−0.21) and SV (0.89). In contrast to DM and SV, the effect of soil WSA on paddy biomass in VR-treated soil was mainly an indirect positive effect, and the direct effect was negative. The corresponding results provided new options and ideas for the efficient utilization of saline soils and high-yield cultivation of paddy. Full article

In the context of limited water resources and the deterioration of natural water bodies’ state, and with the increase in the regulatory requirements for the quality of effluents, assessing the impact of the industrial and energy complex on water bodies is a task of increasingly greater significance to the whole energy sector. “zero discharge” is considered the most effective strategy for creating environmentally friendly thermal power plants. Hybrid reverse osmosis electrodialysis systems make it possible to obtain solutions with a higher concentration of components compared to single electrodialysis treatment, i.e., more efficient separation of brine and pure water. This article proposes experimental and pilot-industrial studies of a hybrid membrane system operation using industrial wastewater for the disposal of liquid waste from an ion-exchange chemical-desalting water treatment plant of a thermal power plant, followed by a calculation of economic efficiency and an analysis of the environmental feasibility of its use. The developed technological scheme offers separate processing of acidic and alkaline waste regeneration solutions using calcium carbonate reagent and desalination on baromembrane and electromembrane units to obtain clean water and dry residue. The hybrid system includes a booster filter press and an evaporator. The hybrid system makes it possible to provide a thermal power plant with a “zero discharge” with a minimum consumption of reagents and electricity, as well as return all wastewater back to the power plant cycle. Full article

The aim of this work is to prevent the public drinking from water coolers, by using an auto-detection process, if the quality of water is low. Therefore, the proposed water treatment management system for allows the activation of dispensers to provide the best-quality water coolers. The objective is to investigate the quality of the drinking water from coolers in public places in Madinah and to provide clean, safe, and healthy drinking water for the general public. The methodology consisted of performing different analyses, tests, and water treatments, such as physicochemical analyses of the water samples, measurements of the different concentrations of anions, measurements of the concentrations of heavy metals, and bacteriological tests of the water samples. Therefore, 66 water samples were tested, and the experimental values were compared with the reference values given by the World Health Organization (WHO) and Saudi Standards, Metrology, and Quality Organization (SASO) for drinking water. The tests revealed that the physicochemical parameters (pH, EC, TDS, and TH) of different water sources (95.5%) were in accordance with the SASO and WHO values. In addition, all the analyzed water samples (100%) contained permissible levels of nitrates, sulfates, nitrites, and free residual chlorine, as indicated by the results. However, 68.2% of the samples studied had fluoride concentrations below the standard limits. Furthermore, heavy metals such as lead, iron, and others were tested for all water coolers. The measured findings indicated that just one cooler exceeded the permissible limit of 0.3 mg/L for Fe, and the biological contamination testing revealed that 4.5% of the coolers were infected with coliforms. Finally, this research suggests that water coolers should be regularly maintained. Additionally, using the best design for the water desalination process is very important to give the best drinking water quality. Full article

Climate change and global warming generate serious consequences and disturbances by drastically modifying historical temperature and precipitation patterns. Water scarcity is one of the most revealing phenomena of these instabilities. This transdisciplinary bibliometric and economic–financial research focuses on analyzing two aspects: first, the feasibility of implementing seawater desalination plants as a solution to water scarcity in northern Chile. Investment and amortization costs of the desalination plants were determined (NPV-IRR-IRP). NPV showed a positive value indicating a recovery of the initial investment and a surplus over profitability. The IRR was higher than the discount rate calculated for NPV, which showed that the investment project was accepted. The IRP indicated that the initial investment of the plant would be recovered in 3.7 years. Second, an innovative and environmentally sustainable solution to the brine (NaCl) waste generated by desalination plants is proposed through the cultivation of Dunaliella salina microalgae tolerant to high brine concentrations to produce β-carotene. The analyzed desalination plants and the sustainable use of brine residues offer interesting economic perspectives to a 10-year projection establishing a surplus over profitability. The SWOT analysis estimates an excellent production of β-carotene through the microalgae and alternatives to the problem of sea pollution by concentrated brine waste. Full article