Desalination Efficiency Research Articles

Utilizing Vigna mungo wash water for simultaneous power generation and desalination using two distinct anodes in a microbial desalination cell

AbstractThis study aims to improve the performance of microbial desalination cell (MDC) using Vigna mungo (Black gram) wash water, reported for the first time as an anolyte utilizing a graphite plate and carbon brush as the anode. Power generation was facilitated by the exoelectrogen, Shewanella putrefaciens MTCC 8104. Polarization studies revealed that the graphite plate MDC attained a high power density of 2720 ± 50 μW/m2 compared to carbon brush for two electrode pairs. The COD removal and desalination efficiency were better for carbon brush MDC, achieving 58.17 ± 2% and 38.14 ± 2% removal, respectively. Power production can be enhanced by increasing the cathode's ability to accept the electrons, reducing the ageing of biofilm and promoting complete oxidation of the substrates. Upon improving its performance, MDC can act as a sustainable technology, collaborating with industries seeking solutions for wastewater treatment, energy generation and agricultural sectors on a large scale.

Application of acoustic oscillations for accelerating the leaching process of saline soils

The escalating expansion of saline soils in arid and semi-arid regions presents a significant challenge to agricultural sustainability. In light of the widespread water scarcity, there has been a growing demand for innovative technologies aimed reducing water during the leaching of saline soils. This study explores the application of acoustic vibrations, particularly utilizing a seismic vibrator SV 10/100, to improve the efficiency of soil desalination. The mechanism of action of acoustic vibrations is explained by the formation of a vortex flow around soil particles oscillating within a defined amplitude and frequency range, thereby enhancing the dissolution of salts. This study specifically targets soda solonetz-solonchak soils with diverse mechanical compositions, situated in the Ararat plain of Armenia. Field experiments utilizing the lysimetric method were conducted in 2016. The primary aim was to determine optimal parameters of acoustic oscillations to expedite desalination process while assessing their impact on soil physical properties during leaching. Findings revealed that higher oscillation amplitudes (ranging from 4 to 7 mm) at frequencies of 10–70 Hz, within a 100-meter radius or 3.14-hectare area were watched. Specifically, oscillations at frequencies of 30–50 Hz for 1.0–1.5 h per leaching water portion (2500 m3/ha) effectively reduced the required leaching water volume and duration by 2 times when applied during soil leaching following acidification. It is important to note that the soil properties after leaching remained in the optimal ranges for the region (soil density 1.2–1.3 g/cm3, hydraulic conductivity 10–20 cm/day). Overall, this research underscores the efficacy of acoustic oscillations in expediting reclamation processes, reducing leaching water requirements, enhancing soil fertility, and facilitating integration into agricultural cycle. Therefore, the newly proposed method of utilizing acoustic vibrations shows potential for efficiently leaching saline soils.

Tailoring the microstructure of zwitterionic nanofiltration membranes via post-treatment for antibiotic desalination

Zwitterionic nanofiltration membranes, with high rejection to organic molecules while low rejection to monovalent salts, are promising for antibiotic desalination. However, due to the heterogeneous issue of interfacial polymerization, the residual amine groups result in polymer chain aggregation via hydrogen bonds, blocking the mass transfer of water and monovalent salts. Herein, EtOH-assisted Michael-addition/Schiff-base reaction strategy was proposed to solve the issue. NaOH was initially utilized to provisionally interrupt the hydrogen bonds between polymer chains. Meanwhile, with the assistance of EtOH, gallic acid diffused into the membrane and reacted with the amine groups on the polymer chains to form covalent bonds, which thoroughly destroyed the stacking of polymer chains. As a consequence, water permeance and antibiotic desalination efficiency of the membrane are improved. For example, the pure water permeance reaches 8.9 L m−2 h−1 bar−1, 1.7-fold enhancement compared with the pristine membrane. The membrane is applied for antibiotic desalination, offering long-term running stability, antifouling ability, as well as high efficiency in concentrated antibiotics.

Electroneutralization desalination with spontaneous chemoelectric power generation

This study designs a novel electroneutralization desalination cell using reaction heat from acidic-alkaline wastewater neutralization to desalinate wastewater and generates chemoelectric power. Several key performance indicators are measured in terms of the energy, environmental and economic aspects of the system, including the ionic flux, the electrical energy produced, the electrical energy consumption for desalination, parasitic losses, overall energy conversion efficiency and desalination performance. The maximum peak power density is ∼31.5 mW/cm2 at 83.5 mA/cm2 and the desalination efficiency is 62 % using brine. The overall energy conversion efficiency is ∼81.8 % and the desalination followed the zero-order reaction. Assuming a 1.5 million litres per day treatment capacity integrated with reverse osmosis, the system has environmental and economic benefits, with 44.5 kg-CO₂eq greenhouse gas emissions per cubic meter of treated brine, and a discounted payback period of 4.2 years. This study demonstrates a pioneering electroneutralization technique for self-sufficient brine valorization and wastewater reclamation.

Water desalination across nanoporous Ti3C2 MXene

Nanostructured materials have a modest thickness, which is comparable in scale to the chemical substances to be separated making them highly efficient in membrane-based separation applications. We performed a molecular dynamics simulation to investigate the effect of the functionalization of the nanoporous Ti3C2 MXene membrane on desalination efficiency. Hydrogenated (–H) and hydroxylated (–OH) pores are the two configurations that we looked at. The calculated water permeability, in the case of hydroxylated (–OH) groups linked to carbon atoms, is equal to 100 L.m−2.h−1.bar−1, and the salt rejection is equal to 100 %.

Enhanced desalination performance of an electrodialysis stack in over-limiting current by adding AC/Fe3O4 nanocomposite as a flow electrode

The primary aim of this study was to investigate the enhanced desalination performance of the electrodialysis (ED) stack under over-limiting current conditions. This was achieved by coupling the flow-electrode capacitive deionization (FCDI) process with the ED stack, incorporating an AC/Fe3O4 nanocomposite (NC) as a flow electrode in the electrode and concentrate compartments. The results obtained indicate that utilizing AC/Fe3O4 NC in the electrode compartment during the ED process, under a potential of 15 V, has led to a significant enhancement in desalination efficiency and current efficiency (CE). Specifically, the desalination efficiency and CE have increased from 60 % to 89.3 % and 35.9 % to 72 %, respectively, compared to the absence of AC/Fe3O4 NC. The desalination efficiency was increased to 93.24 % and the ASRR reached 1.46 μmol cm−2 min−1 by simultaneously adding AC/Fe3O4 NC to the electrode and concentrate compartments. This improvement can be attributed to a reduction in solution resistance, the electro-sorption of ions in the electrical double layer (EDL) of NC, as well as a decrease in ion concentration polarization. Moreover, it is likely that Fe3O4 nanoparticles of NC have resulted in electrical and membrane surface heterogeneity. These factors collectively contribute to the enhancement of the electroconvection phenomenon during the ED process.

Effect of duty cycle and frequency of pulse current on bidirectional electro-migration rehabilitation

In this paper, a new approach of bidirectional electro-migration rehabilitation (BIEM) using pulse currents was proposed. The effect of the duty cycle and frequency of the square wave pulse current on the BIEM was investigated. The results showed that the desalination efficiency was improved by 10 % with the decrease of duty ratio and frequency. Furthermore, With the increase of duty ratio and frequency, the hydrogen permeation of steel bars decreased by 28.5 %. More uniform desalination efficiency was obtained by using pulse current. The half-cell potential of the rebars was also measured and it was higher for the samples using pulse currents than for those using direct currents, indicating a lower risk of corrosion after pulse current treatment. The pH value of the concrete also increased during the BIEM process.

Performance Evaluation of an Enhanced Solar Still Using Simulink

This study focuses on enhancing the efficiency of solar desalination, particularly for small communities facing water scarcity. Despite the economic viability of solar desalination, the method encounters a technical challenge related to low solar yield. The research proposes innovative solutions, notably the integration of a Compound Parabolic Collector (CPC) and Thermal Energy Storage (TES). The CPC system addresses low solar yield by minimizing losses through reflection, significantly improving the capture efficiency of solar radiation. Additionally, TES serves as a strategic storage component, storing solar energy and providing high energy when needed, thereby enhancing water evaporation rates. Using the SIMULINK platform for evaluation, the study demonstrates that the solar still, enhanced with TES and CPC, consistently produces an average of 15 liters of clean water. This positive outcome underscores the effectiveness of the proposed enhancements and suggests avenues for further refinement. The research not only addresses technical challenges but also establishes a foundation for ongoing improvements in solar desalination technology, offering potential solutions for water-scarce communities.

Optimization of Desalination Efficiency and Exploratory Applications of TiO2 Active Site Electrode Enhanced by Activated Carbon and Tween 80 in Capacitive Deionization Technology.

Capacitive deionization (CDI) is an emerging desalination technology for seawater desalination. The development of high-desalination and long-life electrode materials is a research focus in the global water treatment field. In this experiment, Tween T80 was used as a surface activator, and a modified electrode was prepared by facilitating the deposition of TiO2 active sites onto the surface of activated carbon through a sol-gel/hydrothermal two-step synthesis strategy. The morphology and specific surface area of the composite material were analyzed through scanning electron microscopy, specific surface area measurements, and contact angle tests. The results indicated that the sol-gel/hydrothermal two-step synthesis strategy played a crucial role in the homogeneous combination and performance enhancement of the composite material. Under constant voltage mode, when the working voltage was 1.2 V, the desalination capacity of this composite material in a NaCl solution with an initial conductivity of 3000 μS·cm-1 reached 23.8 mg·g-1 (26% higher than materials prepared by conventional sol-gel methods). After 150 cycles, the capacity retention rate was 78%, and the retention capacity was significant (87%). Overall, the results demonstrate the potential of the sol-gel/hydrothermal two-step synthesis strategy in preparing high-performance CDI electrode materials. The modified electrode prepared using this method offers enhanced desalination capacity and durability, making it a promising candidate for seawater desalination and other water treatment applications.

Utilizing a Fe3O4 Magnetite Nanoparticle for Anode Modification in a Microbial Desalination Cell to Treat Saltwater.

The microbial desalination cell (MDC) is a bio-electrochemical system that exhibits the ability to oxidize organic compounds, produce energy, and decrease the saline concentrations within the desalination chamber. The selective removal of ions from the desalination chamber is significantly influenced by the anion and cation exchange membranes. In this study, a three-chamber microbial desalination cell was developed to treat seawater using a synthesize Fe3O4 magnetite nanoparticle (MNP)-modified anode. The impact of different performance parameters, such as temperature, pH, and concentrations of NPs, has been investigated in order to assess the performance of three-chamber MDCs in terms of energy recovery and salt removal. The evaluation criteria of the system included multiple factors such as chemical oxygen demand (COD), Coulombic efficiency (CE), desalination efficiency, as well as system aspects including voltage generation and power density. The highest COD% removal efficiency was 74% at 37°C, pH = 7, and 30g/L salt concentration with an optimized NPs concentration of 2.0mg/cm2 impregnated on anode. The maximum Coulombic efficiency was 10.3% with the maximum power density of 4.3W/m3. The effect of the nanoparticle concentration impregnated on the anode was clarified by the primary factor of analysis. This research has revealed consistent patterns in the enhancement of voltage generation, COD, and Coulombic efficiencies when incorporating higher concentrations of nanoparticles on the anode at a certain point.

Role of microbial electrolysis desalination cell in sustainable water and energy management: Performance assessment of platinum and nickel foam cathodes and simulating integration with reverse osmosis systems

This research introduces the microbial integrated cell (MIC), a bioelectrochemical system that combines microbial electrolysis and desalination for sustainable energy and water purification. Efficiency evaluations of nickel foam and Pt/CC cathodes for hydrogen production and desalination showed nickel foam achieving a 91% desalination efficiency, closely following Pt/CC's 99%, with hydrogen generation rates of 0.96 m3H2/m3/d for Pt/CC cathodes and 0.72 m3H2/m3/d for nickel foam. Despite marginally lower performance, the cost advantages of nickel foam suggest its feasibility for large-scale deployment. Further exploration into MIC integration with reverse osmosis (RO) system aims to enhance the sustainability of the combined system. Simulation outcomes indicate that MIC-RO integration can significantly reduce energy consumption and brine concentration discharged into the sea, highlighting its potential to improve desalination plants' efficiency and environmental impact. This research facilitates the transition of these green technologies to practical applications, optimizing efficiency and environmental benefits.

Solar desalination with charcoal briquettes from plants as an additional absorption sorbent

Water is the most abundant substance on Earth, but only 2.5% can be used for drinking and farming; the rest is seawater containing much salt. Solar desalination is a great tool to solve this problem for small families and remote areas. However, the disadvantage of using solar power is still the low productivity of distillate because it depends on the season, region, and intensity of solar radiation. Solar radiation heat absorbing and storing materials are a favorable solution in increasing evaporation rate, efficiency, and total distillate. Many have been developed to date, but these materials require more expenditure to be used as radiation heat sinks and stores. Charcoal derived from wood has high thermal energy absorption and porosity. Four desalination devices were used, namely using an additional absorber made from Kapok wood (Ceiba pentandra) coded CP_60, Gamal wood (Gliricidia sepium) coded GS_60, Kusambi wood (Schleichera oleosa) coded SO_60, and without additional absorber as a comparison. All desalination devices have the same shape and size, simple, with an area of 0.09 m2 each. Before the additional absorber base material is used, drying, charring, grinding, meshing, pressing, and briquetting are carried out. The test results show that the additional absorber of natural materials affects the evaporation rate, desalination efficiency, and total distillate water. The distillation device using Gamal wood (Gliricidia sepium) additional absorber material, coded GS_60, provides maximum performance such as distillate water yield every 30 minutes and total distillate 124 ml/0.09 m2, 28.19% efficiency, and evaporation rate.

Analysis of an underlimiting and overlimiting current regime in a single electrodialysis channel

Overlimiting ionic transfer is considered a mechanism to intensify transport processes in electrodialysis, potentially providing a smaller required footprint of electromembrane units. However, its applicability in desalination is still questionable. To address this aspect of electrodialysis, we characterized desalination in a single-channel electrodialysis unit operated under various current densities, yielding various diluate desalination degrees. Our analysis revealed that the conditions providing <100 % desalination were pertinent to an underlimiting regime with no indication of overlimiting processes. Specifically, no (electro-) convective structures intensifying ionic transfer occurred in the channel under these conditions. Applying electric current densities yielding theoretical desalination larger than 100 % significantly increased the necessary voltage, driving electroconvective vortices. The observation suggested that overlimiting phenomena occur upon setting conditions corresponding to complete desalination and, thus, do not positively contribute to desalination. Notably, the partial loss of membrane ion selectivity was associated with an operation in the overlimiting regime, worsening desalination efficiency. Our results imply that the overlimiting regime is, at least with the tested membranes, unsuitable for enhancing ionic transfer. Conversely, the small voltage required to remove ions in the underlimiting regime was attributed to the effect of natural convection, which readily occurs in the model system.

On the of seawater desalination environmental impacts and brine treatment based challenges and mitigation measures in Algeria

In this paper the environmental impacts of seawater desalination is investigated and highlighted. Indeed despite the various benefits of desalination there is growing apprehension about the potential negative environmental effects it may bring and generate. Both during the plant construction and its operation service. There is the possibility of leading and causing adverse environmental impacts. A significant concern with desalination is the co-produced and generated waste known as 'brine' or 'reject,' which contains high salinity as well as chemical residuals which are released into the marine environment. Viable and cost-effective brine management systems are necessary to mitigate the negative impact of brine, also referred to as concentrate, which is a by-product of the desalination process. This high salinity substance poses a threat to the environment and must be managed effectively in order to reduce pollution. Aside from brine other difficulties include marine species entrainment and trapping, as well as high chemical use. This paper provides an extensive overview and evaluation of desalination technologies used in Algeria including thermal methods such as Multi-Stage Flash (MSF) and Multiple Effect Distillation (MED) as well as Membrane Reverse Osmosis (RO). Furthermore in order to assess the potential environmental implications of desalination and brine treatment on the Algerian coast, mitigation strategies are proposed to curb the environmental negative impact. To protect water resources for present and future generations, improved brine management techniques are needed to minimize adverse environmental effects and lower the financial burden of disposal. This will encourage further advancements in desalination plants. Ultimately, the paper emphasizes upcoming research opportunities in brine treatment technologies with a focus on improving the efficiency and sustainability of desalination.

Water desalination system via ion immobilization on iron corrosion-based colloids and filtration by kevlar support

An efficient, scalable water desalination line has been introduced based on ion immobilization on the corrosion-based colloids (Diameter: from 10 nm to 20 µm) and filtration by a kevlar support. These particles are generated based on the galvanic cell behavior of some semi-galvanized wiring bundles inside a water medium according to the electrochemical cell schematic: Fe|Fe2+, OH-, H2|H2O with ΔG° of −73.0 KJ mol−1. To have an efficient desalination process, the contributions of different mechanisms such as mixed salt crystals, co-precipitation, and /or formation of various ionic charged species are present. These interactions resulted in the formation of micro/nano colloids (suspensions) with Fe2+ with other cations and anions, randomly, inside the bulk water medium. These particles are sandwiched among the arrays of the kevlar slices (5.0 × 5.0 cm) and play the role of the filter medium. In the introduced water desalination process, the population of the iron-based suspensions is controlled via a descending setting of the mass percentage of the semi-galvanic iron bundling wires along the water desalination line to control the number (population) of iron-based particles. This phenomenon consequently approves the condition for the efficient water desalination process at a laminar mass transfer condition with Reynolds number < 2000. The important factors of the removal efficiency are optimized using a multivariate optimization method based on a controllable waste purification efficiency threshold. This system possesses adequate advantages such as high water desalination efficiency, an acceptable water purification rate (3.0 L h−1, for only one water desalination line), low cost, enough simplicity, no residual water, and no need for any external driving source(s).

Development of a unique integrated bioreactor for simultaneous desalination and bioenergy and biohydrogen production

In the wastewater treatment challenge, it is really essential to develop integrated systems in reducing greenhouse gases, producing green energy and achieving sustainable development. In this regard, an integrated electro-biomembrane reactor was developed and performed in this study for simultaneous biohydrogen (bioH2) production from energetic poplar leaves using dark fermentation (DF) process, conventional H2 production, bioenergy production in the DF process, and saline water desalination in a single system. The results of this study showed that pH was the main controlling parameter in bioH2 production, and the superior production of 40.2 mL/g-biomass was obtained at a pH of 5.5. The maximum current and power density values were 2861.7 mW/m2 and 2819.4 mA/m2 at pH 5.5 under improved conditions. Furthermore, the maximum conventional H2 production was found to be 1341.6 mL using 2 M of KOH solution. Overall, the results further proved that the proposed integrated system can be a sustainable and promising process for industrial applications, considering its high desalination, energy production, and conventional and biological H2 production efficiencies.

Performance Study on Brackish Water Desalination Efficiency Based on a Novel Coupled Electrodialysis–Reverse Osmosis (EDRO) System

Reverse osmosis (RO) is a commonly used desalination technology, but due to high requirements concerning the quality of the feed water, there still exists permeate flux related to the operating conditions, and the solute removal rate is low. Electric fields have a facilitating effect on RO desalination performance. Previous studies have focused on investigating the combination of RO and electrodialysis (ED) processes separately, without directly exploiting their interactions. To address this issue, this study proposes a novel coupling device that combines both RO and ED technologies in a single unit and investigates their mutual enhancement effects on brackish water desalination. The results show that the coupled EDRO system can mutually enhance the performance of RO and ED processes. The permeate flux ratio of the RO membrane increased with increasing voltage, reaching a maximum value of 23.7% at a feed concentration of 10,000 mg/L. The solute rejection by the ion-exchange membrane also increased with increasing pressure, reaching a maximum value of 14.95% at the same feed concentration. In addition, the specific energy consumption of the coupled system was also reduced compared to a standalone operation, with maximum reductions of 9.5% and 19.2% for RO and 2.5% and 3.4% for ED at 5000 and 10,000 mg/L feed concentrations, respectively.

A gravity-induced desalination technology effectively improving the freshwater production efficiency of freeze desalination

Low desalination efficiency and water production efficiency limit the commercial application of freeze desalination (FD) technology. In this study, three freezing temperatures were set to carry out single-stage progressive freezing desalination of brackish water in southern Xinjiang, China. The ice were melted using conventional methods and gravity-induced desalination (GD), and the salt migration law during the icing and melting process was studied. The effect of GD technology on the improvement of the output of frozen desalinated produced water was quantitatively analyzed using scenario simulation. Experimental results showed that salts accumulated towards concentrated water during FD process. The ice total dissolved solids (TDS) increased with decreasing freezing temperature, which was linearly and positively correlated with the raw water TDS. GD efficiency was significantly affected by the salt concentration of ice crystals. In the first stage (the first 450 mL), ice-melt water was salt explosive dissolution, with salt drained mass accounted for more than 85% of the total salt mass. During GD process, exponential decay of ice-melt water TDS (TDSI) was observed with increasing ice-melt water amount. Through the simulation of the two exponential equation scenarios, it was found that Scenario II (mixed water TDSI as the target value) had significantly higher water yield and production rate than Scenario I (TDSI as the target value), with an increase of more than 23%. The algebraic relationship between TDSI of mixed water and the amount of ice-melt water was derived. GD technology can effectively improve the freshwater output efficiency of the FD process, which is manifested by the fact that the ice crystals of the FD process cannot produce freshwater using conventional melting. Scenario II can produce freshwater as high as 69.83% of the total amount of the GD ice-melt water. The GD technology performed increased multiplicatively in WPdv (decrease in water production) and WPRdv (decrease in water production rate) when the TDSI of the mixed water demanded by the user was low. When FD and GD are combined to desalinate salt water, lowering the freezing temperature can significantly increase the freshwater yield, breaking the limitation of freezing temperature for FD. Therefore, an automated, energy-saving freeze desalination-gravity desalination device capable of realizing the collection of the product water according to the users' needs was conceptualized. This study provides new ideas and algorithms for accurately assessing the efficiency of water production in the combined desalination of saltwater by FD and GD.

Anisotropic MXene/Poly(vinyl alcohol) Composite Hydrogels with Vertically Oriented Channels and Modulated Surface Topography for Efficient Solar-Driven Water Evaporation and Purification.

Hierarchical structure and surface topography play pivotal roles in developing high-performance solar-driven evaporators for clean water production; however, there exists a notable gap in research addressing simultaneous modulation of internal microstructure and surface topography in hydrogels to enhance both solar steam generation performance and desalination efficiency. Herein, anisotropic poly(vinyl alcohol)/MXene composite hydrogels for efficient solar-driven water evaporation and wastewater purification are fabricated using a template-assisted directional freezing approach followed by precise surface wettability modulation. The resultant composite hydrogels exhibit vertically oriented channels that ensure fast water supply during evaporation, and their poly(vinyl alcohol) skeletons can reduce the vaporization enthalpy of the water in the hydrogels. The incorporation of MXene sheets enables efficient solar light absorption and solar-thermal conversion while providing structural reinforcement to the hydrogels. More importantly, the as-created undulating solar-thermal surface, featuring modulated hydrophilic troughs and hydrophobic crests, significantly enhances solar-thermal conversion efficiency, thereby boosting solar evaporation performances. As a result, the fabricated hydrogel-based evaporator exhibits an impressive evaporation rate of 2.55 kg m-2 h-1 under 1 sun irradiation, coupled with long-term durability and desalination stability. Notably, the outstanding mechanical robustness of the hydrogel further enables high portability through a readily achievable process of reversible dehydration/hydration.

Experimental study on seawater freeze desalination based on ultrasonic vibration

Seawater freeze desalination is a promising technology with low energy consumption; however, the presence of salt inclusions during the freezing process presents a challenge to enhancing desalination efficiency. While ultrasonic vibration has been proven effective in reducing the supercooling degree and energy consumption in pure water freezing, its impact on seawater desalination efficiency remains to be investigated. This study experimentally explores the characteristics of seawater freeze desalination under ultrasonic vibration. An ultrasonic-assisted seawater freeze crystallizer was designed, and experiments were conducted to compare and analyze the freeze desalination performance of the crystallizer with and without ultrasonic vibration.The findings reveal that ultrasonic vibration significantly enhances desalination by promoting the formation of smaller ice crystals. Compared with ordinary freeze desalination, the desalination rate has increased significantly by 18.18 % -67.86 %, and more significant effects were observed at higher salinity levels. Additionally, the application of ultrasonic vibration accelerates the icing process by approximately 8 %. Notably, during continuous desalination operations, the effectiveness of ultrasonic vibration gradually diminishes as salinity decreases. Nonetheless, the ultrasonic vibration-based freeze-reverse osmosis (Ultrasonic-Freeze-RO) method offers significant advantages in terms of reduced costs and energy consumption compared to both freeze-reverse osmosis (Freeze-RO) and traditional reverse osmosis (RO) methods.