Liquid Discharge Research Articles

Numerical analysis and experimental study for removal of copper and zinc from groundwater by dielectric barrier discharge

ABSTRACT Conventional methods of treating zinc and copper have the disadvantages of secondary contamination and complex control processes. This paper investigates the removal characteristics of gas–liquid mixed dielectric barrier discharge (DBD) in high-concentration copper–zinc groundwater. The study combines numerical simulation and experimentation to analyze the effects of discharge power, initial pH, gas flow rate, and liquid flow rate on copper and zinc removal rates. The results show that a better gas–liquid mixing distribution can be achieved when the inlet flow rate is 40 L/min and the inlet flow rate is below 200 mL/min. The removal of Cu can be up to 98.68% and Zn up to 96.28% when the discharge power is 56 W and the initial pH is 11. The optimum treatment time for Cu2+ is 3–6 min, while the best copper removal occurs at a gas flow rate of 20–30 L/min and a liquid flow rate of 100 mL/min. It was found that the optimum treatment time for Zn2+ was different for different process parameters, mainly in the range of 9–12 min, which needs to be noted in future production applications. Therefore, DBD can efficiently eliminate copper and zinc ions from groundwater to meet environmental discharge standards.

Portable Capillary-Microplasma Optical Emission Spectrometer: Gold-Labeled and Silver-Stained Signal Amplification for Carcinoembryonic Antigen Detection.

Signal amplification techniques based on catalytic silver deposition on immunogold labels have been used for immunoassays. However, conventional instruments often suffer from limitations in point-of-care testing due to their bulky size, high cost, and complex operation. We herein designed an integrated, portable 3D-printed device by integrating capillary liquid electrode glow discharge (CLEGD) with optical emission spectrometer (OES) for the sensitive determination of carcinoembryonic antigen (CEA) in tiny samples. Without the need for additional devices, the sample solution is automatically drawn into the discharge chamber under the action of capillary force and applied high voltage; Ag(I) in the analyte is atomized and excited in the discharge plasma, resulting in Ag atomic emission lines at 328.1 nm. The system enables the detection of 101-106 ng mL-1 Ag(I) and further quantification of carcinoembryonic antigen concentration. Under optimized conditions, the compact equipment achieves CEA detection comparable to that of ICP-OES, with a linear range of 1-500 ng mL-1 and a limit of detection as low as 0.9 ng mL-1.

Advanced plasma hydrogel evaporator for efficient solar-driven saline-alkaline water treatment and agricultural application

Saline-alkaline land significantly impedes social development and urgently requires effective solutions. Solar-driven interfacial evaporation provides a promising green alternative to address this challenge. In this work, a high-efficiency plasma hydrogel evaporator (PHE) was crosslinked by liquid phase pulsed discharge plasma (LPDP) technology within 10 min, followed by a simple freeze–thaw process. The PHE demonstrates remarkable performance in treating saline-alkaline water. Under one solar irradiation, the PHE achieved an evaporation rate of 2.68 kg·m−2·h−1 in saline-alkaline water with high salinity stress (150 mmol·L−1, Na+ concentration). The collected purified water (PW) showed a reduction in total dissolved solids by three orders of magnitude and a significant elimination of alkalinity. To further evaluate the feasibility of utilizing saline-alkaline water resources with the PHE technology, PW was used for maize cultivation, demonstrating a favorable growth trend. Additionally, PHE effectively addressed the limitations of complex fabrication processes and high evaporation enthalpy associated with traditional evaporators. The work offers a cost-effective and promising approach for freshwater shortages, soil salinization, and saline-alkaline water treatment in challenging environments, contributing to sustainable agricultural development.

Sequential separation of oil-in-water emulsions using integrated hydrophilic and Janus membrane modules

Membrane technologies are extensively employed for the separation of surfactant-stabilized oil/water emulsions due to their high efficiency and selectivity. Either membrane filtration or demulsification experiences performance reduction due to the monotonous increase or decrease in emulsion concentration over time. In this study, we have developed a dual-membrane module that integrates a hydrophilic hollow fiber membrane module with a Janus hollow fiber membrane module. This synergistic approach effectively overcomes the limitations of individual filtration and demulsification processes by dynamically adjusting emulsion concentration within the system. Compared to single-membrane modules, the recoveries of both water and oil increased by 27 % and 280 %, respectively. Additionally, the water content in the permeate oil is less than 0.03 %, and the total organic carbon in the permeate water is less than 12 ppm. Furthermore, this design allows for the concurrent recovery of oil and water from emulsions, offering a promising approach to achieving zero liquid discharge.

Janus channel of membranes enables concurrent oil and water recovery from emulsions.

Existing separation technologies struggle to recover oil and water concurrently from surfactant-stabilized emulsions to achieve the goal of near-zero liquid discharge. We present a Janus channel of membranes (JCM) that features a confined architecture constructed of a pair of hydrophilic and hydrophobic membranes, which allows for concurrent, highly efficient recovery of oil and water from surfactant-stabilized emulsions. The confined Janus channel can amplify the interplay of the membrane pair through a feedback loop that involves enrichment and demulsification. Our JCM achieves exceptional oil and water recoveries of up to 97 and 75%, respectively, with near 99.9% purities. Moreover, its versatility in handling diverse emulsions may enable near-zero liquid discharge for a range of separations.

Microplastics removal from a hospital laundry wastewater combining ceramic membranes and a photocatalytic membrane reactor: Fouling mitigation, water reuse, and cost estimation

The release of microplastics (MPs) through industrial laundry wastewater accounts for 35 % of global MPs emissions into the environment and it is a significant environmental problem, especially because MPs can absorb contaminants of emerging concern (CECs) from garments. This study is the first to evaluate and perform a cost estimation of the MP removal from hospital laundry wastewater (HLWW) using a combination of ceramic membranes and a pilot-scale photocatalytic membrane reactor (PMR) as a fouling mitigation strategy. The HLWW, from a hospital in Copenhagen, Denmark, contained a total organic carbon (TOC) of 345 mg L⁻1 and 1.4 × 106 MP L−1, mainly of polyethylene terephthalate (PET) ranging between 100 and 200 μm in size. The pre-treatment with an ultrafiltration (UF) ZrO₂ membrane successfully removed 96 % of MPs and over 98 % of suspended solids and turbidity at an estimated cost of 0.45 US$ per m3 of permeate. In the PMR stage, ultraviolet light emitting diodes (UV LED) irradiation reduced irreversible fouling, improving permeate flow and minimizing the need for chemical cleaning. The Ce–Y–ZrO2/TiO2 photocatalytic membrane achieved over 99 % removal of turbidity, colour, and suspended solids, as well as 99.9 % removal of MPs, allowing the potential effluent reuse within the hospital laundry. Additionally, the retentate from the PMR process had lower TOC, easing the discharge of this concentrated stream. The cost estimation demonstrated that the photocatalytic degradation combined with traditional techniques, i.e. backflush and chemical cleaning, is more economical than using these techniques separately. Therefore, the total treatment cost was 1.09 US$ per m3 of permeate, which is lower than the cost of fresh water in Denmark. In conclusion, this innovative treatment strategy offers a sustainable and cost-effective solution for HLWW management, not only reducing water consumption by enabling water reuse in the hospital laundry but also advances towards achieving net-zero liquid discharge and contributing to the UN Sustainable Development Goals for clean water (Goal 6) and climate action (Goal 13).

An efficient process for decomposing perfluorinated compounds by reactive species during microwave discharge in liquid

Abstract Microwave discharge plasma in liquid (MDPL) is a new type of water purification technology with a high mass transfer efficiency. It is a kind of low-temperature plasma technology. The reactive species produced by the discharge can efficiently act on the pollutants. To clarify the application prospects of MDPL in water treatment, the discharge performance, practical application, and pollutant degradation mechanism of MDPL were studied in this work. The effects of power, conductivity, pH, and Fe2+ concentration on the amount of reactive species produced by the discharge were explored. The most common and refractory perfluorinated compounds (perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in water environments are degraded by MDPL technology. The highest defluorination of PFOA was 98.8% and the highest defluorination of PFOS was 92.7%. The energy consumption efficiency of 50% defluorination (G50-F) of PFOA degraded by MDPL is 78.43 mg/kWh, PFOS is 42.19 mg/kWh. The results show that the MDPL technology is more efficient and cleaner for the degradation of perfluorinated compounds. Finally, the reaction path and pollutant degradation mechanisms of MDPL production were analyzed. The results showed that MDPL technology can produce a variety of reactive species and has a good treatment effect for refractory perfluorinated pollutants.

Analysis of energy, water, land and cost implications of zero and minimal liquid discharge desalination technologies

Desalination is increasingly essential to ensure access to water as climate change and population growth stress fresh water supplies. Already in use in water-stressed regions around the world, desalination generates fresh water from salty sources, and in doing so forms a concentrated brine that requires disposal. There is a growing push for the adoption of zero/minimal liquid discharge (ZLD/MLD) technologies that recover additional water from this brine, thereby reducing the liquid volumes requiring disposal. In this analysis, we evaluated the cost, energy and sustainability impacts of 7 overarching treatment trains with 75 different configurations. We found ZLD/MLD water recoveries ranging from 32.6% to 98.6%, but with steep energy and cost trade-offs that underscore the crucial roles of ion-specific separations, heat integration and clean energy sources. We explored the key trade-offs between cost, energy and water recovery, elucidating the increasingly tight connections that are central to the energy–water nexus and desalination.

Performance improvement of triple-doped nanocomposite membrane towards hairwork dyeing effluent reclamation approaching zero liquid discharge

It is highly anticipated that efforts will be made to raise the level of industrial effluent reclamation on the background of continuously minimizing waste stream based on preconcentration tool. For this purpose, a triple-doped nanocomposite (TFN-tri) membrane through partially alternative doping spiro-structured 2,2'-dimethyl-1,1'-biphenyl-4,4'-diamine dihydrochloride and flexible 4,4'-bipiperidyl dihydrochloride and continuous incorporating of molybdenum disulfide quantum dots was successfully fabricated. With the assistance of self-synthesized biodegradable flocculant pretreatment, raw hairwork dyeing effluent (HDE) was stably recycled up to 95.1% on the premise of meeting the requirements of the relevant national standard. As a deep processing unit, TFN-tri membrane displayed accurate salt rejection of nearly 66% as expected. More impressively, it also exhibited permeability basically increased by 2.5 folds, while fouling layer thickness, running time and specific energy consumption decreased by 5μm, 54.7% and 72.5%, respectively, than its counterpart in long-term reuse testing. These changes may mainly be due to the finely expand sub-nanopores coupled with an enhanced electrostatic exclusion and the improved fouling resistance brought about by other critical skin features in terms of smoothness and hydrophilicity optimization. In brief, this study has taken a vigorous and reliable step towards heavily polluted HDE reclamation approaching zero liquid discharge.

Superhydrophobic pancake-like graphene oxide for zero liquid discharge solar desalination of real brines

Solar interfacial desalination offers a promising solution to meet the demand for portable water, especially in arid regions. Although various materials have demonstrated high solar-to-steam conversion efficiencies in concentrated solutions, most studies have utilized simulated solutions rather than real seawater. Herein, we developed a pancake-like graphene oxide photothermal membrane with superhydrophobic properties optimized for interfacial heating to desalinate real seawater and brine. Under 1 sun, the membrane efficiently achieves a sustained high evaporation rate of 1.23 kg.m−2.h−1 with a photothermal conversion efficiency of 80 %, while remarkably facilitating salt harvesting. Notably, the membrane maintained stable performance and exhibited no salt accumulation on its surface when tested outdoors with real seawater, demonstrating its practical scalability. The membrane exhibited long-term stability in desalination processes, with full performance restoration through an energy-free cleaning method. These results highlight a potential pathway toward zero-liquid discharge desalination.

Effect of nozzle clogging on vortexing during continuous casting processes: results of an experimental simulation

ABSTRACT Exogenous oxide inclusions in continuously cast steel primarily arise from the entrapment of slag during various stages of steelmaking, including in furnaces, ladles, and molds. To maintain steel cleanliness, operators often pause ladle and tundish processes before ‘slag vortexing’ begins, since this phenomenon (slag vortexing) can adversely affect product quality. Previous studies indicate that sub-entry nozzle clogging can lead to productivity issues and quality defects in cast products. Clogging can cause non-uniform reductions in nozzle diameter along the molten metal flow direction. This study examines the impact of drain port taper (a representation of nozzle clogging) on air core vortex formation during water drainage (simulating molten metal) using a parameter, ‘Characteristic Volume of Air Core.’ Results show that clogged drain ports are prone to vigorous vortexing, significantly affecting efflux velocity and static pressure at drain outlets. The current study also analyzes the dynamic behavior of air core vortexing due to nozzle clogging, revealing that clogging can induce fluctuations in liquid discharge, adversely affecting the casting process. These findings have practical implications for continuous casting processes in steel and other metals.

Toward circular greenhouse wastewater reuse: advancements in cation exchange membranes for selective Na+/K+ separation using electrodialysis systems

ABSTRACT Driven by the growing need for alternative water sources and forthcoming stringent nutrient discharge regulations, there is growing interest in developing selective membrane solutions to facilitate circular greenhouse wastewater reuse (as emphasized in the European Union's Horizon 2020 ULTIMATE project). For electrodialysis systems, sodium (Na+) over potassium (K+) selective membranes are essential to achieve minimal liquid discharge. This study addresses the challenge of developing selective, efficient, and scalable Na+/K+ cation exchange membranes. State-of-the-art cation exchange membrane developments were reviewed and the functionalization of commercial membranes with crown ethers was identified as a promising approach. Two crown ether–modified membranes (15-crown-5 (15C5) and 18-crown-6 (18C6)) were developed, characterized, and tested in equimolar and greenhouse wastewater binary feed ratios. While the results demonstrated low overall selectivity, the 15C5-modified membrane showed a marginal enhancement in K+ selectivity, suggesting the need for further optimization. The study concludes with recommendations for the future development of Na+/K+ selective membranes, highlighting the potential of machine learning approaches to expedite progress. This research provides a foundational step toward practical and scalable Na+/K+ ion separation solutions, for achieving minimal liquid discharge in greenhouse horticulture.

Simultaneous recovery of ammonium sulfate and ice from aqueous solution using eutectic freeze crystallization process

This study investigated the feasibility of eutectic freeze crystallization (EFC) process for ammonium sulfate (AS) salt recovery from 41 wt% AS solution. The EFC experiments were conducted using a 1 L double-jacketed crystallizer coupled with a recirculating chiller under varying freezing time, seed mass and seed size. The EFC process demonstrated successful AS salt recovery and water purification with the highest ice purity attained at 96.28 %. The construction of a binary AS-water phase diagram allowed the determination of the eutectic temperature, which was found to be −19.06 °C at 40 wt% of AS solution. The results indicated that the increase in freezing time enhanced the AS nucleation rate, growth rate, yield and mean product crystal size. The introduction of seeding not only provided well-controlled crystal nucleation and growth during EFC process, but also promoted the formation of larger, well-structured crystals and reduced agglomeration. Overall, the EFC process is a viable and promising option for recovering AS from wastewater, which offers high potential towards achieving zero liquid discharge goal, i.e. a sustainable and efficient approach in managing industrial effluent rich in ammonium and sulfate contaminants.

Study of the effect of pore properties of microporous layer on water transport process in proton exchange membrane fuel cell

Aiming at the “water flooding” phenomenon inside the Gas Diffusion Layer (GDL) of the Proton Exchange Membrane Fuel Cell (PEMFC), this paper visualizes the effects of the pore properties and gradient structure of the microporous layer (MPL) on water transport. Specifically, we visualize the impact of pore properties and gradient structure on water transport. For this purpose, a liquid water capillary finger advancement visualization test platform is constructed to analyze the evolution of liquid water in the porous medium and reveal the effects of single porosity, single pore diameter, gradient porosity, and gradient pore diameter of the MPL on the liquid water transport. Moreover, the time of the non-wetting liquid touching the top, the maximum spreading length, and the residual volume in the MPL are analyzed to evaluate the drainage capacity. The results highlight that the microporous layer's smaller porosity and pore size could limit the interface's extended width between the microporous and gas diffusion layers. Additionally, the residual volume of non-wetting liquid is 21.6 % less in the case of φ = 0.3 than for φ = 0.45, and the residual volume of non-wetting liquid is 11.8 % less in the case of d = 0.82 mm compared to d = 2.45 mm. Furthermore, the residual volume of the microporous layer in the Catalyst layer (CL) side of the microporous layer is 11.8 % less than that in the case of d = 2.45 mm. Finally, we conclude that when the pore gradient law is opposite, it is unfavorable for liquid water discharge.

Chiral Metal-Organic Framework Films with Ordered Macropores for Enantioselective Analysis of Proteins.

Chiral film-based sensors show great promise for discriminating between enantiomers due to their miniaturization and low power consumption. However, their practical use is hindered by the trade-off between enantioselectivity and mass transfer capability, especially concerning biomacromolecules such as proteins. In this work, we present an effective and straightforward method for creating highly organized macropores within crystalline chiral metal-organic framework (CMOF) films. This approach harnesses the shaping influence of a polystyrene nanosphere template and the crystallization induced by the liquid dielectric barrier discharge plasma. The resultant highly ordered macro-microporous structures improve mass diffusion and access to chiral active sites in the hierarchical CMOF films. Coupled with their inherent chirality, strong fluorescence emission, high crystallinity, and exceptional stability, these attributes endow these CMOF films with enhanced sensing capabilities for chiral molecules. Particularly, the macro-microporous structure facilitates efficient protein recognition, overcoming a significant challenge encountered by MOFs due to protein dimensions surpassing MOF pore sizes. These films exhibit increased enantioselectivity, better limits of detection, and wider linear ranges compared with purely microporous CMOF films. This study thus provides a powerful synthetic approach for hierarchical CMOF films, addressing the limitations of traditional thin film sensors and opening an avenue for efficient chiral sensing of large biomacromolecules.

Exergy based yearly performance analysis of a poly-generation system for a small-town application

The current study conducts a comprehensive year-round exergy analysis of an integrated system centered around a reversible solid oxide cell (RSOC), aimed at fulfilling the power and fresh water requirements of a small town, equivalent to 2.7 MW and 2000 m³/day, respectively. The integrated system encompasses four subsystems: the solar field, RSOC, organic Rankine cycle coupled with ejector cooling (ORC), and zero liquid discharge multi-effect desalination (MED-ZLD). The proposed system is analyzed using MATLAB. The annual exergy efficiency for each subsystem is examined, yielding average values of 11.9 %, 48.11 %, and 56.22 % for the solar field, ORC cycle, and MED-ZLD, respectively. Notably, the exergy efficiency of the Rankine cycle is higher in colder months compared to warmer ones. This phenomenon is attributed to the cycle's greater heat generation relative to the cooling it produces during the cold season. The RSOC exhibits noteworthy average exergy efficiencies of 93 % in electrolysis mode, 69.87 % in fuel cell mode, and an overall average exergy efficiency of 79.62 % throughout the year. The average exergy efficiency of the overall system is evaluated throughout the day, nighst, and the entire operational period. The results are values of 10.74 %, 34.31 %, and 23.34 %, respectively. This discrepancy is due to the primary energy supply source, which is solar energy during the day and input hydrogen during the night. The highest exergy efficiency is observed in December, while the lowest is in June. Furthermore, the study examines the distribution of exergy destruction and identifies cycles with significant impacts by analyzing the exergy destruction ratio across various months. The solar field is the primary contributor to daytime exergy destruction, peaking at 94.9 %. At night, the MED-SET cycle leads in exergy destruction, followed closely by the RSOC cycle operating as a fuel cell. The research also delves into exploring key contributors to exergy destruction in various cycles, shedding light on crucial insights into the intricate dynamics of the integrated system's performance.

Emerging and Conventional Water Desalination Technologies Powered by Renewable Energy and Energy Storage Systems toward Zero Liquid Discharge

The depletion of fossil fuels has become a significant global issue, prompting scientists to explore and refine methods for harnessing alternative energy sources. This study provides a comprehensive review of advancements and emerging technologies in the desalination industry, focusing on technological improvements and economic considerations. The analysis highlights the potential synergies of integrating multiple renewable energy systems to enhance desalination efficiency and minimise environmental consequences. The main areas of focus include aligning developing technologies like membrane distillation, pervaporation and forward osmosis with renewable energy and implementing hybrid renewable energy systems to improve the scalability and economic viability of desalination enterprises. The study also analyses obstacles related to desalination driven by renewable energy, including energy storage, fluctuations in energy supply, and deployment costs. By resolving these obstacles and investigating novel methodologies, the study enhances the understanding of how renewable energy can be used to construct more efficient, sustainable, and economical desalination systems. Thermal desalination technologies require more energy than membrane-based systems due to the significant energy requirements associated with water vaporisation. The photovoltaic-powered reverse osmosis (RO) system had the most economically favourable production cost, while MED powered via a concentrated solar power (CSP) system had the highest production cost. The study aims to guide future research and development efforts, ultimately promoting the worldwide use of renewable energy-powered desalination systems.

A Review of Renewable Energy Powered Seawater Desalination Treatment Process for Zero Waste

Freshwater resources have faced serious threats in recent decades, primarily due to rapid population growth and climate change. Seawater desalination has emerged as an essential process to ensure a sustainable supply of freshwater to meet the global demand for freshwater. However, this approach has some shortcomings, such as the disposal of brines containing high levels of contaminants creating environmental problems, and the energy-intensive nature of desalination, primarily powered by fossil fuels, which contribute to greenhouse gas emissions. Consequently, as a solution, the zero liquid discharge approach has been identified by the body of research to be one of the viable methods to solve these problems. Over 90% of freshwater and reusable salts could be recovered through this approach. Adopting renewable energy-powered systems could make zero-liquid discharge desalination plants operate in an entirely environmentally friendly and sustainable manner. This review explores the integration of renewable energy-powered systems for the optimisation of seawater desalination treatment processes for zero-waste and improved productivity. The review also examines technologies and strategies that improve the efficiency and sustainability of desalination systems. By analysing recent research, we provide insights into the advancements, challenges, and prospects for optimizing renewable energy-powered seawater desalination processes aimed at achieving zero waste.

Detection of Partial Discharge in Liquid via Interferometry

Detection of Partial Discharge in Liquid via Interferometry

Practice and Exploration of Ground Engineering for Pilot Testing of Offshore Gas Storage Facilities

Abstract The N gas storage facility is an offshore gas storage facility for oil reservoir reconstruction. There is no successful experience to learn from in the construction and operation of surface engineering. Therefore, a pilot experiment centered on economic benefits and fully utilizing the existing facilities in the oilfield has been carried out. Unlike traditional underground gas storage facilities, the construction difficulties of offshore gas storage facilities are more prominent. By strengthening design management, procurement management, construction management, testing management, and HSE management, the construction of gas storage facilities is efficiently promoted and successfully put into operation, achieving the experimental goal. In the construction and operation practice, facing many difficulties such as the evaluation and governance of old systems, inconvenient maritime transportation, long procurement cycle of compressors, and unsuitable production and operation, we have explored management methods such as utilizing old and leasing compressors, reasonable coordination of sea transportation, and adjustment of production parameters. We have innovated technologies such as soaking cleaning+steel wire ball unblocking and cleaning, small pipe capacity short distance series injection, and rapid construction of gas lift liquid discharge warehouses, Provide reference significance for the construction of similar gas storage facilities.