Liquid Discharge Research Articles

Current Status of Zero Liquid Discharge Technology for Desulfurization Wastewater

Desulfurization wastewater is industrial wastewater with a high salt content, high metal ions, and high hardness produced by flue gas desulfurization of the limestone-gypsum method in coal-fired power plants. This paper summarizes the source of desulfurization wastewater, water quality characteristics, water quality impacts, and other factors, combined with the current status of research worldwide to introduce the advantages and shortcomings of the existing desulfurization wastewater treatment technology. In addition, zero liquid discharge technology as a novel method to treat desulfurization wastewater is also summarized. It mainly includes evaporation and crystallization, flue gas evaporation, membrane distillation removal, etc. Finally, this manuscript looks forward to the future development direction of desulfurization wastewater based on its existing technology and emission standards.

Multistage membrane-integrated zero liquid discharge system for ultra-efficient resource recovery from steel industrial brine: Pilot-scale investigation and spatial membrane fouling

Zero liquid discharge (ZLD) strategy provides significant potential for industrial brine treatment. Still, the application has been constrained by the inadequate water recovery and membrane fouling of its membrane-based brine concentration system. Herein, a pilot-scale system was established that integrated pretreatment, reverse osmosis (RO), nanofiltration (NF), and disk tube reverse osmosis (DTRO), and demonstrated over a 6-month operation for the first application in treating steel industry brine. Meanwhile, novel insights were offered into the spatial evolution of DTRO membrane fouling. The overall ZLD system reached ultra-efficient water recovery at 91% with relatively low energy consumption (7.27 kWh/m3). The RO and NF units concentrated the brine and selectively separated ions of different valences, simultaneously eliminating various contaminants. The DTRO unit enriched the highly saline NF permeate with a remarkable 7.5-fold concentration effect, producing an extremely hypersaline brine salinity (138,472 ± 34,804 mg/L, Cl−/SO42− mass ratio of 56) that ultimately yielded ultra-pure NaCl salt. Additionally, DTRO special fouling patterns revealed a distinctive "W"-shaped fluctuation in humic acid along the device water flow, with concurrent reduction in iron/aluminum oxides leading to their deposition at the outlet. This synergistic fouling, coupled with silicon, coincides with the transformation of silica colloids into silicate compounds. The multistage membrane-based strategy and the spatial membrane fouling evolution pattern proposed and investigated in this work provide a highly efficient and cost-effective solution for industrial brine treatment with ZLD.

Electrodialysis of moderately concentrated solutions: Experiment and modeling based on a simplified characterization of ion-exchange membranes

Electrodialysis (ED) is a cost-effective and environmentally friendly process; it is considered a key step in Zero Liquid Discharge systems. However, the ED process producing a fairly concentrated solution is not well understood. An ED process where 10 L of 0.5 M NaCl was circulated in diluate stream (DS) and 0.1 L of initially 2.0 M NaCl circulated in concentrate stream (CS) was studied. The concentration of concentrate increased up to 3.5 M. The electrodialyzer's design eliminated current leakage. Ion-exchange membranes, MK-40, MA-41 (Shchekinoazot) and CJMA-3 (Chemjoy Polymer Materials), were characterized prior to ED. Based on the concentration dependences of membrane conductivity and diffusion permeability, the “true” (ti⁎) ion transport numbers in the membranes were found; the water transport number (tw) was found from volumetric measurements. It was shown that the current efficiency, η, found using ti⁎ is quantitatively consistent with η found in the ED experiments. To calculate the time dependences of solution concentration and volume in CS, a mathematical model was built. For the first time, ti⁎ and tw determined in independent experiments, were used as parameters. The only fitting parameter was the osmotic permeability coefficient. A good agreement with experimental results is obtained.

Step-rate-test as one of the strategies for managing formation water injection. Design and monitoring

The construction of a produced water management (PWM) system relies on a Step-rate-test strategy that integrates a novel technology for treating the bottomhole formation zone and adjacent fractures resulting from prior hydraulic fracturing. Step-rate-test technology is considered more environmentally friendly than hydraulic fracturing for several reasons. It doesn't require crosslinkers or proppants, and there is no discharge of liquids or other reagents onto the terrain or into water basins. This article discusses technical approaches to solving field service problems in injection wells. One of the strategies for managing produced water injection is Step-rate-test, which is considered the best choice in these operations. This strategy can also be used to solve the problem of disposing of excess fluid or waste after hydraulic fracturing. Advances in modelling, operation, monitoring, and evaluation provide the basis for minimising costs and preserving the environment. The connection between the object of work and the engineering works is established through quality targets and pumping requirements. Field example, such as Tevlinsko-Russkinskoye and Yuzhno-Yagunskoye, and results of data mining of them, demonstrate the significant impact of data differences on site selection. Field data indicates that injectivity decreases in matrix injection structures despite the injection of prepared fluid. It is acceptable to inject the fluid without prior preparation, provided that there is no well pad pump station, pipe end phase divider or similar equipment. The majority of rock structures become fractured during fluid injection, which affects the selection of technical equipment for the process. This article evaluates the propagation of fractures during the injection of prepared and unprepared fluids and their impact on well performance.

Enhancing water recovery through integrated graphene oxide-modified forward osmosis and membrane distillation for real textile wastewater treatment

The textile industry is a highly water-intensive sector, emphasizing the increasing importance of reclaiming clean water from textile wastewater and advancing water recovery towards zero liquid discharge. This study proposes and assesses an integrated forward osmosis and membrane distillation (FO-MD) process for treating real textile wastewater, aiming for enhanced water recovery and ensure robustness towards zero liquid discharge. Firstly, a newly developed graphene oxide (GO)-enhanced FO membrane (GFO) was fabricated by adding GO into the polyamide layer during the interfacial polymerization process. Furthermore, the real textile wastewater treatment performance of the FO-MD process based on the GFO membrane was compared to that of a commercial FO membrane (CFO). The results indicated the GFO-based FO-MD process outperformed due to enhanced antifouling properties and stable water flux. Remarkably, the GFO membrane-based FO-MD system achieved over 80% water recovery and nearly 100% rejections for COD, Na+, K+, Cl-, and S2- during continuous 24-hour filtration. The findings highlighted FO-MD as a viable solution, surpassing the individual FO and MD processes by overcoming the limitations of FO draw solution dilution and MD membrane wetting challenges. Moreover, a preliminary techno-economic study for a 200 m3 day−1 textile wastewater estimated water production costs of $6.48 m−3 and $5.73 m−3 for CFO-MD and GFO-MD systems. The analysis highlighted maintaining the water flux above 10 L m−2 h−1 is crucial for economic viability. This work demonstrates the potential of the FO-MD system as a sustainable solution to address the textile wastewater treatment challenges, providing insights for FO-MD system design and optimization.

Gradient Graphene Spiral Sponges for Efficient Solar Evaporation and Zero Liquid Discharge Desalination with Directional Salt Crystallization.

Solar desalination is a promising strategy to utilize solar energy to purify saline water. However, the accumulation of salt on the solar evaporator surface severely reduces light absorption and evaporation performance. Herein, a simple and eco-friendly method to fabricate a 3D gradient graphene spiral sponge (GGS sponge) is presented that enables high-rate solar evaporation and zero liquid discharge (ZLD) desalination of high-salinity brine. The spiral structure of the GGS sponge enhances energy recovery, while the gradient network structures facilitate radial brine transport and directional salt crystallization, which cooperate to endow the sponge with superior solar evaporation (6.5kgm-2h-1 for 20wt.% brine), efficient salt collection (1.5kgm-2h-1 for 20wt.% brine), ZLD desalination, and long-term durability (continuous 144h in 20wt.% brine). Moreover, the GGS sponge shows an ultrahigh freshwater production rate of 3.1kgm-2h-1 during the outdoor desalination tests. A continuous desalination-irrigation system based on the GGS sponge for crop growth, which has the potential for self-sustainable agriculture in remote areas is demonstrated. This work introduces a novel evaporator design and also provides insight into the structural principles for designing next-generation solar desalination devices that are salt-tolerant and highly efficient.

Electrodialysis for fluoride and nitrate removal from synthesized photovoltaic industry wastewater-toward high performance experimental parameters

This study focuses on the use of electrodialysis (ED) process as a mean to treat contaminated ultra-pure water (UPW) from the photovoltaic (PV) industry, for the elimination of two major ions pollutants that are fluoride and nitrate ions. Synthetic solutions, simulating contaminated UPW from the PV cells rinsing step, were used. Both ions were eliminated significantly after 15 min of treatment time with an initial concentration of 140 mgL−1, and 33 min with an initial concentration of 1000 mgL−1 for fluoride and nitrates ions, respectively. The study of the competition between these two ions in their eliminations showed that the presence of fluorides does not disturb the elimination of nitrates (no competition), while the presence of nitrates in the solution strongly affects the elimination of fluorides by delaying the treatment time from 15 to 53 min. In addition, the concentrations of pollutants in the treated solutions are lower than the standards recommended by the World Health Organization (WHO); consequently, the treated UPW can be reused in the process to achieve near Zero Liquid Discharge (ZLD). From a techno-economic standpoint, the ED technique under these experimental conditions could reduce the production price of photovoltaic cells. In effect; the total investment can be amortized in a few years, making this water treatment a viable alternative since UPW is expensive and its consumption is very important in this industry.

Holistic managements of textile wastewater through circular, greener and eco-innovative treatment systems developed by minimal to zero liquid discharge

New pragmatic and viable solutions to reduce or prevent discharge and to protect reserves are currently among the top-prioritised research for cleaner, circular, and resource-efficient use of industrial waters. So, the development of eco-sustainable water management is essential for green industrial development that will meet versatile and eco-sensitive regulatory standards, especially in water-intensive industries. Textile wastewater was reclaimed in semi to fully closed loops for minimal to zero liquid discharge. Concentrate-mixed wastewater was steadily treated in a hybrid membrane oxidation reactor at 60–80 % synergistic performances with remarkable UF fluxes of 96.4–820 L/m2h without any sludge discharge. Effluent was purified with 90–100 % removals and 20–80 L/m2h in nanofiltration and reverse osmosis. Due to Fenton-specific operation, more handling by ion exchange and neutralisation required to harvest membrane reuse waters and reactor discharge effluents with guaranteed Fe and pH. All-in-one system simulations indicated that high quality reuse waters are produced by 99.9 % efficiency and 98 and 100 % savings in iron and acid but 20–51 % more oxidant through concentrate recycling and regenerant reuse. It was also revealed that reactor effluents can be released to the sea or conventional biological treatment or can be eco-sustainably exploited for in-situ chemical and ex-situ bio-induced recovery of vivianite. This research demonstrates that how textile wastewater can be managed holistically by liquid discharge approaches from 50 % minimal to 99.9 % zero just in two-step, i.e. pretreatment and pre-concentration, with consumable minimisation and valuable waste recovery through the eco-innovative systems which are developed as circular, greener, and sludge-free compatible with sustainable development goals.

Sustainability Evaluation of the Al-Qasab Playa by Integrating Hydrogeochemical and Graphical, ArcGIS Watershed, and Thermodynamic Geochemical Modeling Approaches

Drawing development plans requires evaluating the available resources and assessing their sustainable and subsequent utilization-driven environmental impacts. The current work is concerned with evaluating the sustainability of the halite harvesting process from Al-Qasab Playa, Shaqra, Central Saudi Arabia. The authors integrated, conceptually and quantitatively, ArcGIS-processed SRTM-DEM (Shuttle Radar Topography Mission-Digital Elevation Model) data, hydrogeochemical and thermodynamic-based geochemical modelling, and graphical approaches to achieve the ultimate aims of the study. The watershed is identified as a nonmarine closed basin with a drainage area of 1290 km2, with the slope controlling recharge to the Playa. The Chadha plot including the rainwater exhibits linear regression, with an R2 value of 0.9947, confirming the rainwater origin of the Playa water. The hardness-forming ions are primarily removed in pond 3, eliminating the need for costly and power-consuming steps of softening with ion exchange resins or nanofiltration as it can be used directly as a readily available feed for the chlor-alkali process for producing NaOH, Cl2, and H2 gases through electrolysis. XRD (X-ray diffraction) analysis and the SEM-EDS (Scanning electron microscopy-energy dispersive X-ray spectroscopy) of the harvested halite confirmed its purity. An improved design of the current folkloric harvesting process has been proposed based on the saturation indices calculated thermodynamically to provide a readily available feed intake for the electrolysis chlor-alkali process with or without minimal pretreatment to produce higher value chemicals. The methodological aspects presented here are deemed robust and valid for applications in other study areas, including the assessment of the exploitation of the rejected brine from the desalination plants to achieve the zero liquid discharge approach, as well as other types of sabkhas, regardless of their geographical location.

Boosting the performance enhancement of short-process regenerated Ni-rich cathode via antimony doping and modification

Currently, the short-process regeneration of cathode materials in spent lithium-ion batteries has attracted wide attention from researchers because of its short process flow, less waste liquid discharge and the cascade utilization of recycled materials. However, the performance of short-process regenerated electrode materials is generally difficult to comparable with the commercial materials, especially for lithium nickel cobalt manganese oxide (NCM). Herein, antimony (Sb) doping, and modification is proposed to boost the performance enhancement of short-process regenerated NCM in our work. Spent NCM is first selectively leached by oxalic acid, and then directly dried to obtain the precursor without separation and filtration. Finally, NCM is regenerated by lithium supplement and Sb doping modification. The regenerated NCM with optimal Sb doping modification (R-Sb10) has better electrochemical performance and cycle stability. It delivers an initial specific discharge capacity of 152.3 mAh/g, and the capacity retention maintains 86.3 % after 200 cycles at 0.5C, which can be comparable to the commercial NCM. The Sb element can be evenly distributed in the interior of short-process regenerated NCM, especially with a protective Li3SbO4 film on the surface. Through theoretical calculation, the R-Sb10 has a lower energy for material formation, higher energy barrier for cation disorder and decreasing diffusion energy barrier for Li+. The doping modification method provides a new idea to improve the performance of regenerated materials and is expected to meet the needs of industrial applications in the future.

High-pressure batch reverse osmosis (RO) for zero liquid discharge (ZLD) in a Cr(III) electroplating process

A batch RO system was designed and built for high-pressure (120 bar) operation. The system was developed for a ZLD application involving treatment of metal plating wastewater from a Cr(III) electroplating process at a major industrial plant. Hybrid semi-batch/batch operation enabled a compact design to be achieved. To maximize water recovery without exceeding a set peak pressure, a method for controlling the switch point between semi-batch and batch phases was developed. The system was tested with feed representative of rinse water from the electroplating process. A range of feed concentrations (at 10–20× dilution of the plating bath), feed flows (0.21–0.46 m3/h), water fluxes (6–14 LMH) and water recoveries (87–95.7 %) were investigated. The system successfully recovered Cr(III) and restored its concentration to that of the electrolyte bath, thus meeting the requirements for reuse in the electroplating process. Rejection of most species was >99.8 %, sufficient for reuse of the permeate as rinse. However, rejection of boric acid was only 69–80 % such that a second RO pass may be needed to remove boric acid. Specific Energy Consumption was <2.25 kWh per m3 of treated rinse water, representing a 50-fold saving compared to the current method of treatment and disposal at the industrial plant.

Seeded membrane distillation crystallization for hypersaline brine treatment

Abstract Brine evaporation and crystallization are energy- and equipment-intensive technologies commonly used in industries. Alternatively, membrane distillation (MD) has shown ability for concentrating different saline solutions. However, there is a limited understanding of the impact of these solutions on the scaling and wetting behavior. To address this knowledge gap and reduce costs and energy consumption, we investigated a novel method called ‘seeded near-zero liquid discharge membrane crystallization’ (NZLDMC). This approach combines MD and crystallization in a single apparatus, reducing capital and operating costs while improving sustainability. Our study focused on applying seeding processes at NZLDMC for concentrating synthetic mono- and multi-salt solutions with a salinity of 300 g/L and a real salt solution. We investigated the effects of salt crystals and seeds on membrane performance under different operating conditions. Our findings indicate that seeding crystal technology leads to high yield and long-term stability, thereby offering the potential in industries and municipal water treatment to fractionate salt in multi-salt solutions and obtain purified water simultaneously.

An approach to highly polluted wastewater management for zero liquid discharge: The case of landfill leachate

This work aims to bring the treatment of highly polluted wastewater to the concept of zero liquid discharge, using landfill leachate as a representative example. Achieving this goal involves removing pollution due to organic matter and/or heavy metals and recovering the nutrients contained in the effluent. Thus, the sequential combination of thermally activated persulfate and the Fenton reagent is proposed to eliminate the high concentration of organic matter. This avoids the need of pH adjustment to meet the Fenton process operation criteria and minimizes the amount of persulfate and, consequently, the conductivity in the treated effluent. Furthermore, this solution is particularly attractive in systems with excess energy, such as urban solid waste facilities where biogas is generated. Nutrient recovery (N in the case of landfill leachate) is carried out through precipitation in the form of struvite. Finally, if necessary, a further nanofiltration stage is proposed to minimize the conductivity of the treated effluent, making it suitable for on-site use. Under the optimized operating conditions (Flow rate: 0.5 L h−1, residence time 60 minutes, 0.3 and 0.7 times the stoichiometric amount of persulfate (12 g/g COD0) and H2O2 (2.12/g COD0), respectively, a H2O2/Fe2+ ratio of 50/1 and 85°C), a 90% removal of COD is achieved, along with 99% and 95% recovery of the nitrogen content in the effluent and reclaimed water, respectively, confirming the feasibility of this solution as an approach to a more sustainable waste management.

Fault mechanism and dynamic two-phase flow behavior of liquid slugging in reciprocating compressors

Liquid slugging is a fatal fault for large process compressors, leading to transient overpressure, the deformation and fracture of vital pressure-bearing parts, and even gas leakage or explosion. In the study reported here, to reveal the mechanism of overpressure formation, numerical simulations were conducted by means of the volume-of-fluid method to explore the dynamic evolution characteristics of the two-phase flow pattern. Then, high-speed photography was applied to capture the dynamic changes of the liquid boundary in the modified cylinder from different views, thus realizing the validation of the numerical model. This study reveals the significant influence of increased rotational speed on fluid flow patterns, impeding liquid discharge and exacerbating overpressure events. Additionally, changes in pressure waveform and a distinctive waveform feature were identified as effective diagnostic indicators for detecting fluid slugging. Next, a nondestructive pressure monitoring reconstruction method based on measuring bolt strain was proposed. The strain-based pressure showed good agreement with the simulated results, thereby validating its effectiveness and feasibility as an early warning indicator for liquid slugging. This study offers new perspectives on the failure mechanism of liquid slugging in reciprocating compressors by delving into the behavior of two-phase flow, with the potential to enhance the theoretical foundation of compressor condition monitoring and fault diagnosis.

Solvent extraction desalination applied to desulphurization wastewater towards zero liquid discharge: Parameters analysis and energy evaluation

With massive impurities, desulphurization wastewater is difficult to achieve zero liquid discharge (ZLD). The present paper proposes a novel ZLD technology based on solvent extraction desalination (SED) to avoid the intensive use of high-grade electrical energy and steam. Three amines are compared for the water extraction and salt precipitation performance from desulphurization wastewater simulated by NaCl and Na2SO4 solution. Results show that with the same volume ratio, diisopropylamine exhibits the optimized extraction performance, while N,N-dimethylcyclohexylamine has the highest ions removal efficiency of over 98 %. Diisopropylamine is selected as the target solvent for further evaluation regarding its feasibility. The detailed analysis indicates that for 100 mL of wastewater, the corresponding solvent volume to achieve ZLD is 300 mL, 400 mL and 600 mL when the extraction temperature is 5°C, 10°C and 15°C, respectively. High water recovery efficiencies and salt removal efficiencies within five repeated ZLD tests highlights the reusability performance of SED. In addition, a novel SED-ZLD system with the flue gas before desulphurization as heat source is proposed. Thermodynamic calculation results show that for 5 t/h of wastewater, less than 50,000 m3/h of flue gas is sufficient for heating. Energy evaluation suggests that although SED-ZLD system consumes more energy, the exergy values of the heat source is much lower than that of multiple effect distillation or reverse osmosis, highlighting the superiority in waste heat utilization.

Cyanide removal from aqueous solution by oxidation with hydrogen peroxide in the presence of activated alumina-supported copper catalyst

&lt;p&gt;Cyanide compounds are widely used in some electroplating, chemical and metallurgical industries. They are often found in their liquid discharges. This work highlights the performance of an activated alumina-supported copper catalyst in the removal of cyanide by oxidation with hydrogen peroxide in aqueous solution. The influence of catalyst dose, initial molar ratio of hydrogen peroxide/cyanides, temperature, and catalyst reuse was studied. The activated alumina-supported copper significantly enhanced the reaction rate showing a good catalytic activity. The efficiency of cyanide elimination was increased after 30 minutes of oxidation from 48% to 98% by increasing the catalyst dose from 1 to 10 g/L. Rising the temperature from 30°C to 40°C promoted cyanide removal. The catalyst can be recycled four times and show good stability. The kinetics of cyanide oxidation was revealed to be pseudo-first order with regarding cyanides. The rate constants as well as the activation energy were determined.&lt;/p&gt;&#x0D;

Innovations in textile wastewater management: a review of zero liquid discharge technology.

Zero liquid discharge (ZLD) technology emerges as a transformative solution for sustainable wastewater management in the textile industry, emphasizing water recycling and discharge minimization. This review comprehensively explores ZLD's pivotal role in reshaping wastewater management practices within the textile sector. With a primary focus on water recycling and minimized discharge, the review thoroughly examines the economic and environmental dimensions of ZLD. Additionally, it includes a comparative cost analysis against conventional wastewater treatment methods and offers a comprehensive outlook on the global ZLD market. Presently valued at US $0.71 billion, the market is anticipated to reach US $1.76 billion by 2026, reflecting a robust annual growth rate of 12.6%. Despite ZLD's efficiency in wastewater recovery, environmental challenges, such as heightened greenhouse gas emissions, increased carbon footprint, elevated energy consumption, and chemical usage, are discussed. Methodologies employed in this review involve an extensive analysis of existing literature, empirical data, and case studies on ZLD implementation in the textile industry worldwide. While acknowledging existing adoption barriers, the review underscores ZLD's potential to guide the textile industry toward a more sustainable and environmentally responsible future.

Enhanced charge carriers separation/transportation via S-scheme ZnCeS–ZnWO heterostructure nanocomposite for photodegradation of synthetic dyes under sunlight

Domestic wastage and liquid discharge from industries cause serious water pollution and severely damage the life cycle of living species. Therefore, it is necessary to construct efficient photocatalysts for the removal of toxic pollutants from water. Herein, a novel heterostructure ZnWO–ZnCeS nanocomposite was prepared by the sol-gel route and studied its physical and photocatalytic properties using various analytical techniques. Under sunlight irradiation, the ZnWO–ZnCeS photocatalyst eliminated 99.7, 99.1, 99.0 % rhodamine-B (RhB), methylene blue (MB), and safranin-O (SO) dyes within 70 min with excellent performance higher than individual ZnWO and ZnCeS catalysts. The optimization tests exhibit the catalyst loading = 30 mg, dye content = 25 ppm, solution pH = 8 of ZnWO–ZnCeS against MB dye for practical application. The heterojunction of coupled ZnWO and ZnCeS leads to a synergistic effect that facilitates the charge transport and hampers the recombination of photo-induced charge carriers thereby leading to boosted photocatalytic performance. Furthermore, based on the scavenging test, the hydroxyl and superoxide radicals were the reactive species during the photodegradation reaction. The designed photodegradation reaction mechanism has proposed the formation of an S-scheme in ZnWO–ZnCeS that led to the accumulation of electrons at ZnCeS and holes at ZnWO, favoring the formation of reactive species for dye degradation. Moreover, this work provides a novel direction to synthesize S-scheme heterostructure photocatalysts for application in wastewater treatment.

CO2 nanobubbles as a novel kinetic promoter in hydrate-based desalination

The use of CO2 nanobubbles (NBs) was investigated as a sustainable kinetic promoter of gas hydrate formation in hydrate-based desalination (HBD) that does not require any separation steps from the recovered water. Stable CO2 NBs (8.07 ± 0.21× 107 bubbles/mL with 103.15 ± 2.47 nm mean radius and −6.35 ± 1.17 mV zeta potential) were generated and tested in HBD experiments conducted at 274.15 K and 3.58 MPa. The colloidal stability of CO2 NBs increased under pressure: their concentration increased and their size decreased. Low concentrations of dissolved chloride salts reduced the size of CO2 NBs, while high concentrations increased the likelihood of NBs' agglomeration. The induction time for CO2 hydrate formation in the presence of CO2 NBs was reduced by 86.04 %. The desalination results confirmed that CO2 NBs played a significant role in accelerating the process based on the memory effect mechanism. In the presence of CO2 NBs, water recovery reached 68.85 ± 1.82 % and 63.37 ± 2.76 % with an ion removal efficiency of 41.35 ± 6.16 and 40–50 % in a single-stage HBD process for 0.5 M NaCl and synthesized seawater solutions, respectively. These findings could unlock the potential for the further development of HBD of natural saline solutions as well as its deployment in near-zero liquid discharge industrial processes.

Two-phase flow dynamics study in the trapezoidal gas channel of PEM fuel cell based on lattice Boltzmann model

ABSTRACT Water management is a critical challenge in ensuring the performance and durability of low-temperature proton exchange membrane fuel cells (PEMFCs). This study utilizes the phase-field lattice Boltzmann method to conduct three-dimensional numerical simulations, investigating the dynamics of two-phase flow in the cathode gas channel (GC) of PEMFC with a trapezoidal cross-section. The effects of the water inlet location, the surface wettability of GC, the open angle of GC, and the air velocity on liquid water distribution and discharge are analyzed. The results indicate that positioning the water inlet in the middle of the GC significantly enhances PEMFC performance while having minimal impact on average pressure drop. A wall contact angle of 70° or 110°Can optimize fuel cell performance from different directions. Setting a wall contact angle at 70° optimizes gas flow stability and maintains a low-pressure drop value for the GC. A wall contact angle of 110° focuses on optimizing gas reactant diffusion ability into porous electrodes and GC drainage rate. An opening angle of 55° for the trapezoidal gas channel improves overall fuel cell performance. Increasing air velocity facilitates the film flow formation of liquid water on top wall surfaces within the GC.