Scale Removal Research Articles

Fouling management in oceanic carbon capture via in-situ electrochemical bipolar membrane electrodialysis

To assist reaching net-zero emissions, the dissolved carbon in the ocean can be extracted to enable an indirect air capture. An electrochemical bipolar membrane electrodialysis (BPMED) is a sustainable method for such capture. The BPMED enables a pH-swing that manipulates the oceanic carbonate-equilibrium using electricity. However, at alkaline-pH, an in-situ process suffers from inorganic fouling within the stack, increasing the cost of capture. In the current work, we investigate fouling management strategies including fouling control (i.e., membrane- configuration and current-flow rate optimization) and fouling removal methods. Fouling removal methods including air and CO2(g) sparging, dissolved CO2 (aq) cleaning, back-pressure, flow rate increase, and acid-wash are investigated under accelerated fouling conditions. The stack configuration containing the BPM-AEM pairs shows 4 × lower fouling than the BPM-CEM stack, while the carbonate-extraction and faradaic efficiency are similar for both configurations. From the scaling removal methods, only the acid wash combined with the back-pressure removed all the inorganic fouling, recovering both the cell voltage and pressure drop to their initial values. Upon the air sparging, the total cell voltage and pressure drop increased even more due to the trapped gas inside the netted spacers. Cleaning via dissolved and gaseous CO2 decreases the cell pH, dissolving hydroxide/carbonate-based fouling, but decreases the carbonate-removal significantly which is not preferred. Applying the back-pressure and higher flow rates decelerated the scaling buildup but was not enough to remove the fouling. Using BPM-AEM stacks in combination with periodic acid cleaning has potential as resilient oceanic carbon removal via BPMED.

Rolled metal electron plasma treatment for automotive hardware cold upsetting

One of the most important objectives of the modern car production development is to improve the quality of metal products and parts made from it, increase their efficiency, reliability, service life, bringing these indicators to the level of the world standards, ensuring the competitiveness of domestic products at the foreign market. The structural safety of motor vehicles is largely determined by the operational reliability of the constituent elements. Car fasteners made of high-carbon and alloy wire, including hardware items, are among the critical and widely used parts in mechanical engineering. The most common and progressive method of their manufacture is the cold upsetting from rolled bar material. The bar material surface condition has a significant impact on its quality. Hot rolled products from metallurgical plants are typically delivered to the processing facilities covered with scale and rust. To improve the surface quality of semifinished metallurgical products for rerolling at the stage of wire preparation for drawing, it is subjected to continuous mechanical or chemical cleaning. Traditionally, the technology of surface scale removing by etching is used in production. This method of scale removal provides a high level of cleaning, but there are problems with the disposal of spent acid solutions, reducing the steel ductility. Mechanical methods of scale removal have been widely introduced recently, although the use of mechanical scale removal devices also does not completely solve the problem. The paper considers the possibility of using advanced electron plasma treatment technologies for these purposes and the influence of traditional methods and this scale removing method from the rolled steel surface on the quality of metal preparation for upsetting.

Roses Greenhouse Cultivation Classification Using Machine Learning Techniques

There is a demand for flowers globally all year round, more particularly roses, necessitating increased production for flowers. Demand for roses has increased due to their year-long availability as well as its uses in cosmetic, perfume, medicinal products, food raw materials and decoration industry. Rose plants are prone to drastic fluctuations in temperature, drought stress damages, and low precipitations. These resulted to an increase in greenhouse production to generate optimum supply to meet growing demands as controlled environment provides several advantages. In this study, four machine learning models (random forest, support vector machine, multinomial logistic regression, and artificial neural networks) were applied to roses greenhouse cultivation dataset. The study aims to classify the most suitable greenhouse environment to upgrade the roses state leading to the optimal production of roses. Four model configurations corresponding to the pre-processing techniques were tested. These were scaling only, scaling plus removal of outliers, scaling plus SMOTE, and scaling with removal of outliers plus SMOTE. Random forest with all pre-processing steps applied to the dataset obtained the best performance with the highest weighted F1- scores, weighted-average precision, weighted-average recall, and Cohen's kappa statistic. This indicates that machine learning models can predict corrective actions leading to improved conditions of roses. The notable contribution of this research is to find valid and reliable classification models that assist growers in predicting the best greenhouse micro-environment.

Synthesis of novel solid scale inhibitors based on silver tungstate loaded KIT-6 for scale removal from produced water: static and modeling evaluation.

Oilfield scaling is a major problem in the oil and gas industry. Scaling issues cost the industry millions of dollars in damage and lost production every year as scaling is one of the main causes of global production decline. In this study, solid scale inhibitors based on silver tungstate loaded KIT-6 were synthesized and evaluated using a static scale inhibition test. The synthesized materials were characterized using wide and low XRD, N2 adsorption-desorption, TGA, and FTIR, SEM, and XPS analyses. Small-angle XRD patterns showed that KIT-6 had 3D-mesopore diffraction peaks with a cubic Ia3d space group. Wide-angle XRD patterns of silver tungstate loaded KIT-6 confirmed the crystallinity. The prepared catalysts are characterized by higher surface areas (394-918 m2 g-1), large pore volumes (0.63-0.98 cm3 g-1), narrow pore size distributions (5.3 nm), and high thermal stability up to 1000 °C. The results of this study demonstrate that the inhibition efficiency of the scale inhibitor increases and that of the calcite scale inhibitor decreases with increasing pH (2 to 8). This proposes that the scale inhibitor is more effective under alkaline conditions. An inhibition efficiency of 99% on calcium carbonate can be achieved at an optimal dosage of 7.5 ppm at 55 °C, indicating that the scale inhibitor exhibits a relatively good inhibition performance on calcium carbonate. The use of these materials can potentially lead to more efficient and cost-effective solutions for scale inhibition in various industrial processes.

Efficiency Improvement of the Process of Cleansing from Scale the Carp Carcass Cyprinus carpio with Ultrasonic Processing Use

Topicality. The article presents data and substantiates the feasibility of ultrasonic processing use while cleansing the carcass of commercially caught pond fish from scale on the example of carp. Purpose and methods. The aim of this research is to improve the process of cleansing carp Cyprinus carpio carcass from scale using ultrasonic processing by estimating the practical model that describes the relationship strength scale-skin fish. In the course of the study, analytical, theoretical and experimental methods have been applied, using control and measuring equipment of appropriate accuracy, standard methods for examining food raw materials, modern methods of mathematical statistics, correlation analysis, and computer technologies. Results. Based on the results of experimental data evaluation, the theoretical dependence of the scale-skin bond strength on the mass of pond fish carcass has been confirmed. The conducted experimental studies made it possible to determine the strength of the scale-skin bond for pond fish carcass in the native and chilled states, and to calculate, based on the experimental data, the value of the k3 coefficient for carp. While using this, it becomes possible to calculate the strength of the scale-skin bond for carcass of any weight group in theoretical way. Experimental studies gave an opportunity to fix the change in the strength of the scale-skin bond for carp carcass of industrial catch in conditions of storage in a chilled form. This dimension was found to vary a little, and the scale-skin bond strength in the native state could be used in order to elaborate the specification for the scale removal device. The dynamics of changes in the strength of the scale-skin bond under the influence of ultrasonic processing of fish raw materials was determined. It was revealed that the greatest influence on the change in the scale-skin bond was exposed to ultrasonic vibrations with a frequency of 22 kHz. So, the use of the specified frequency reduced the processing time by 27...34% for carp. This phenomenon can be explained by the fact that the selected frequency (22 kHz) has the highest oscillation amplitude of ultrasonic end of the emitter. Conclusions and discussion. It has been established that the ultrasonic frequency, the mass of fish carcass and the duration of processing have a decisive influence on the efforts of the scale-skin bond. The scale-skin bond ratio for Cyprinus carpio carp carcass in the native state was calculated, the value of which is 2.29. During the experimental studies, it was highlighted that the magnitude of the scale-skin bond coefficient for carp carcass changes insignificantly, and the strength of the scale-skin bond in the native state can be used to elaborate the terms of reference for the apparatus for removing scales. The greatest influence on the change in the scale-skin connection in conditions of ultrasonic processing was recorded at an oscillation frequency of 22 kHz. Prospects for further scientific research are to found the implementation of a complex process for cleansing fish carcass from scale, in particular, removing the fish guts, which can affect the reduction in the energy content and material consumption of the corresponding processes.

The effects of calcium carbonate precipitation on high-velocity flow behavior in 3D printed fracture models

A large amount of water is produced in oil and geothermal fields. Produced water is used in water injection for oil displacement and pressure maintenance in oil fields. However, there is a possibility of forming different precipitations when the injected water and formation water combine, which can cause serious problems in the reservoirs. In the world, more than 60% of oil and more than 40% of gas reservoirs are fractured carbonate rocks, and the mineral precipitation observed in these formations is mostly CaCO3 due to temperature and incompatibility between the injected and formation water. There are few techniques available for CaCO3 scaling removal due to their relative hardness and low solubility. In most cases, the scaled-up wells are caused by the formation of carbonate. In the well tests, it is seen that the flow from the matrix to the fracture is quite low, and the flow in the fracture dominates the whole flow. Therefore, it is essential to properly understand the kinetics of CaCO3 scale formation and its detrimental effect on fracture.It is known from studies that kinetic models can give better results in determining precipitation behavior. However, there are not enough experimental studies on the effects of flow on mineral precipitation in fractured media. Therefore, the kinetic and thermodynamic models are used in this study to reliably predict the amount of mineral precipitation. This work investigates the behavior of precipitation in different temperature conditions, laminar or turbulent flow conditions, and fracture properties like high roughness, length, and aperture. The amounts of precipitation in fracture under different conditions that have not been determined in the literature are given. After flow experiments, the amount of CaCO3 precipitation and pressure differences were measured. When the temperature is 80 °C, the flow rate is 4.16 × 10−5 m³/s, and the roughness is high, precipitation is 47.5% higher than when the temperature is 50 °C. Repeating the same fracture characteristics for different flow conditions in fracture flow tests is essential. By using 3D fracture models, the same fracture properties were obtained under different flow conditions.In addition to precipitation amounts, this article presents decreasing crack permeability due to precipitation. Precipitation of minerals can drastically influence the reservoir's permeability and ability to transmit mass and energy. With the pressure differences measured in the experiments, permeability decreases due to precipitation were calculated using Poiseuille's law (cubic law) for laminar flow and Forchheimer's equation for turbulent flow. After 3.5 days of flow, the study's permeability at high roughness and high flow decreased by 23% at 50 °C and 44% at 80 °C. This study's findings can help better understand that the permeability reduction of fracture is greater in turbulent flow conditions compared to laminar flow. In addition, temperature and high roughness are very effective parameters in precipitation and permeability change. At high temperatures and high roughness, more minerals precipitate, and permeability values decrease considerably. In the later injection periods, the decrease in permeability caused by the precipitation can make the fracture impermeable and increase the pressure losses during the injection.

Study on Unblocking and Permeability Enhancement Technology with Rotary Water Jet for Low Recharge Efficiency Wells in Sandstone Geothermal Reservoirs

In China, sandstone geothermal reservoirs are large in scale and widely distributed, but their exploitation is hindered by low recharge efficiency. In this paper, an unblocking and permeability enhancement technology using a rotary water jet for low recharge efficiency wells in sandstone geothermal reservoirs is proposed to solve this problem. This paper presents a series of studies about the proposed technology, including experiments, simulation and field application. Firstly, an experiment was carried out to verify the scale removal effect of a high-pressure water jet on the inner wall of the screen tube and its impact on sandstone. Secondly, the numerical models of the rotary jet flow field in the wellbore were established by ANSYS Fluent to study the influence of parameters. Finally, based on the simulation and experiment results, a rotary jet tool applicable to unblocking and descaling low-efficiency wells was designed, and a field application for low-efficiency wells in sandstone thermal reservoirs was conducted. The study results show that the unblocking and permeability enhancement technology using a rotary water jet is effective in removing the blockages and improving the permeability near the well. In conclusion, the presented technology can solve the problem of low efficiency during the reinjection of cooled thermal waters back into sandstone geothermal reservoirs and has great effectiveness in field application.

Cleaning mechanism of gypsum scaling in hydrophobic porous membranes

Mineral scaling is one of the major challenges for membrane distillation in concentrating high-salinity brine. This work first investigated the characteristic of CaSO4 scaling, then explored different cleaning reagents to evaluate their efficiencies and mechanisms. By analyzing the SEM and EDX mapping images, the CaSO4 scaling process could be divided into surface and pore scaling stages. Three cleaning solutions, i.e., commercial detergent (20 %), EDTA-4Na (0.05 M), and MgCl2 (0.8 M), were chosen for their high CaSO4 solubility (0.7 g CaSO4 per 100 g H2O). At the surface scaling stage, three cleaning solutions exhibited excellent removal of CaSO4 scaling with approximately similar 96 % cleaning efficiencies. However, at the pore scaling stage, only the commercial detergent showed high efficiency (89 %). Such high cleaning efficiency was mainly attributed to the detergent's high total dissolved solids (salinity), low pH, and high diffusion rate (5.46 μm cm−1 min−1) across the membrane. Moreover, periodic cleaning at the surface scaling stage with the commercial detergent followed by drying throughout a 43.5 h continuous concentration test on an actual RO brine could restore the PTFE membrane performance completely, giving 90 % of the total water recovery. This work provides new insights into the cleaning mechanism for gypsum scaling in a hydrophobic porous membrane.

Bench scale investigation of the effects of a magnetic water treatment device in pool systems on chlorine demand

Chlorination is the most common form of water disinfection for recreational swimming pools and represents a major cost for many large-scale operations. Reducing the chlorine demand in a system may alleviate these costs by decreasing the amount of chlorine required to maintain a target disinfection residual. While magnetic water treatment is common for removal of pipe scale, impacts on chlorine demand have not been evaluated. The application of a commercial magnetic treatment device significantly (p < 0.05) reduced the chlorine demand by 13.8 % within 24 h, due to a reduction of monochloramine (NH2Cl), when applied to a simulated pool system. Subsequent breakpoint chlorination through the addition of calcium hypochlorite (CaOCl2) resulted in a 30.8 % increase in free chlorine concentration. Additionally, a 1-h exposure to the magnetic field resulted in a 6.1 % reduction in monochloramine compared to the control, demonstrating that transient flow-through treatment can yield a reduced yet still significant effect. Mechanistically this effect could be due to the magnetic field effects (MFE) influencing the electron configuration of compounds in the system, thus altering reaction equilibria to favor more volatile chloramine species. This treatment is potentially a cost-effective method to improve the efficiency of chlorination via the demonstrated reduction of chlorine demand.

STUDY ON DESCALING CHARACTERISTICS OF 304 STAINLESS STEEL USING PICKLING AND ABRASIVE WATER JET

The variability in the surface integrity, mechanical properties and corrosion resistance of the surface layer of 304 stainless steel after scale removal by pickling and an abrasive water jet, removing the oxide and Cr-poor layer was studied comparatively. It was found that the surfaces of the pickling specimens were etched with pits of varying sizes, with Ra of 4.384 µm and Rz of 24.81 µm, while the surface microhardness fluctuated in a range of 200–220 HV. The surfaces of the abrasive water jet specimens exhibited a stack laminar characteristic, Ra of 3.960 µm and Rz of 22.63 µm, while the surface microhardness decreased with an increase in the distance from the surface; the surface microhardness increased from the original 210 HV to 380–390 HV, producing a 1-mm deep work-hardening layer, which had a great impact on the microhardness of the substrate 0–0.3 mm from the surface. For both the pickling specimens and the abrasive water jet specimens, the material tensile strength and yield strength were slightly increased, and the elongation after fracture was significantly reduced. The corrosion resistance of the pickling specimens was better than that of the abrasive water jet specimens. The surface layer of the AWJ specimens generated a Cr-poor layer due to severe secondary oxidation, and the corrosion resistance of the material was reduced.

Corrosion of tensile wires covered with PA11 layers in simulated annulus environments at low CO2 pressure

AbstractHigh‐strength carbon steel wires covered with polymer layers were exposed to different test environments simulating the conditions in the annulus of flexible pipes at low CO2 pressure and flooded with seawater. The polymer layers mimicked the antiwear tapes which are placed in between the steel layers of the tensile armor of the pipes. Specimens without the polymer layer were exposed to the same test environments for comparison and allowed identifying how the presence of the polymer layer influenced the corrosion mechanism. In some of the experiments, oxygen was introduced into the gas mixture to simulate fresh seawater entering the annulus after a breach in the outer sheath. Surface analysis of the corroded specimens after removal of corrosion scales was carried out by scanning electron microscopy, optical profilometry, and confocal microscopy. The polymer layers were observed to have a considerable effect on the corrosion morphology.

Sorption of Ni(II) by sol-gel silica functionalized with DMG and other chelating agents

In this study, a comprehensive investigation of doping of sol-gel silica with DMG and other chelating agents is provided at room temperature using infrared spectroscopy, elemental analysis, SEM, EDS and powder XRD. Sol-gel silica was doped with dimethyl glyoxime (DMG), ethylenediamine (EDA), 1,10-Phenanthroline (Phen), dithizone (DZ), and sulfanilamide (SB) to investigate the sorption of Ni(II) from aqueous media. It is observed that the chelating agents are encapsulated by the pores of the xerogel from where they interact with the metal ions by ion exchange and chelation mechanism. Nickel complexes of the chelating agents were also synthesized. Sol-gel silica was doped with metal complexes for comparison with sol-gel silica with sorbed metal ions. Ni(II) in metal complex was compared with that in functionalized silica from EDS of both samples. The batch adsorption experiments were performed at room temperature and neutral pH. The developed method can be applied on large scale removal of Ni(II) using silica and chelating agents from cheap natural sources. The sorption process was completed within 5 minutes and 0.1 N HNO3 resulted in complete desorption of metal ions. The regenerated sorbent can be reused six times with negligible loss of sorption capacity.

The interplay between microbial reservoir souring and barite scale formation in hydrocarbon reservoirs

The injection of seawater into a hydrocarbon reservoir (seawater flooding) as a secondary or tertiary oil recovery method is associated with two possibly significant challenges. First, the formation and deposition of various types of scale may happen due to incompatibility between the injection seawater and formation brine. Especially, the addition of sulfate ions may trigger the formation of various types of sulfate scales (e.g., barium sulfate, strontium sulfate, and calcium sulfate). Second, microbial reservoir souring may happen due to the activation of Sulfate Reducing Bacteria (SRBs), which reduce sulfate ions to hydrogen sulfide. This is mainly a result of a drop in temperature in the reservoir, the addition of sulfate from the seawater to the reservoir, and the presence of Dissolved Organic Carbon (DOC) coming from reservoir hydrocarbon. Since both these processes include the consumption of sulfate ions, a competition is expected to happen between them. Especially, there is a concern about whether an efficient mitigation strategy for souring (e.g., nitrate treatment) will result in less consumption of sulfate ions and in turn more formation of sulfate scales. This study tests this theory and investigates the effect of souring intensity and mitigation on the severity of barite scale formation inside the reservoir. In this study, a non-isothermal multi-component bio-chemical model to simultaneously simulate both the processes is developed. Several simulation cases in one and two dimensions are investigated in different conditions in order to study the effect of three influential parameters, namely sulfate ion concentration in the injection sweater, the DOC content of the reservoir hydrocarbon, and injection flow rate on barite scale formation, microbial reservoir souring, nitrate treatment, and the interplay among them. The results show that the effect of barite scale formation on reservoir souring is small (a maximum of 4 percent reduction in the total generated hydrogen sulfide) whereas reservoir souring and nitrate treatment significantly influence barite formation. Depending on the case, the presence of souring can cause a complete removal of barite scale especially around the production well (positive effect) or a maximum of 8 times increase in barite scale amount around the production well (negative effect). Moreover, in all cases, with a more efficient nitrate treatment, although less hydrogen sulfide is generated inside the reservoir (up to a full removal of souring), the generation zone moves closer to the production well. Therefore, an insufficient nitrate treatment may cause an earlier hydrogen sulfide production from the production well (up to twice as early). Several other trends observed in the set of results are also presented in this paper.

Removal of Iron Oxide Scale From Boiler Feed-Water in Thermal Power Plant by Magnetic Separation-Scale Removal at High-Temperature

The removal of scale by high gradient magnetic separation (HGMS) has been investigated utilizing the magnetic properties of the scale. This study focuses on a thermal power plant with oxygen treatment (OT), which has been applied in many new power plants with large generation capacity in recent years. At high-temperature conditions where the HGMS system is expected to be installed, the viscosity of the fluid will be lower than that of at room temperature, which makes the separation ratio higher. In this study, the scale capture rate at room temperature (25°C) and 80°C was investigated by particle trajectory calculation and experiment, in order to design magnetic separation conditions suitable for the high-temperature environment of the chemical cleaning line of the thermal power plant adopting OT.

Removal of Scale-Forming Ions and Oil Traces from Oil Field Produced Water Using Graphene Oxide/Polyethersulfone and TiO2 Nanoribbons/Polyethersulfone Nanofiltration Membranes.

Treatment of produced water in oil fields has become a tough challenge for oil producers. Nanofiltration, a promising method for water treatment, has been proposed as a solution. The phase inversion technique was used for the synthesis of nanofiltration membranes of polyethersulfone embedded with graphene oxide nanoparticles and polyethersulfone embedded with titanium nanoribbons. As a realistic situation, water samples taken from the oil field were filtered using synthetic membranes at an operating pressure of 0.3 MPa. Physiochemical properties such as water flux, membrane morphology, flux recovery ratio, pore size and hydrophilicity were investigated. Additionally, filtration efficiency for removal of constituent ions, oil traces in water removal, and fouling tendency were evaluated. The constituent ions of produced water act as the scaling agent which threatens the blocking of the reservoir bores of the disposal wells. Adding graphene oxide (GO) and titanium nanoribbons (TNR) to polyethersulfone (PES) enhanced filtration efficiency, water flux, and anti-fouling properties while also boosting hydrophilicity and porosity. The PES-0.7GO membrane has the best filtering performance, followed by the PES-0.7TNR and pure-PES membranes, with chloride salt rejection rates of 81%, 78%, and 35%; oil rejection rates of 88%, 85%, and 71%; and water fluxes of 85, 82, and 42.5 kg/m2 h, respectively. Because of its higher hydrophilicity and physicochemical qualities, the PES-0.7GO membrane outperformed the PES-0.7TNR membrane. Nanofiltration membranes embedded with nanomaterial described in this work revealed encouraging long-term performance for oil-in-water trace separation and scaling agent removal.

Leachate Pretreatment before Pipe Transportation: Reduction of Leachate Clogging Potential and Upgrading of Landfill Gas.

Leachate and landfill gas are the main contaminants produced by modern sanitary landfills. The leachate easily leads to clogging in the leachate transportation pipe, and the landfill gas can be used as renewable energy after the removal of CO2. The study aims to investigate the removal of the major scale forming ion of Ca2+ in leachate using raw landfill gas before pipe transportation. The research demonstrated that, under the given experimental conditions, the removal rate of Ca2+ in the leachate was positively correlated with the pH value of the leachate, and negatively correlated with the intake flow rate of the landfill gas; the highest removal rate of Ca2+ was achieved when the intake flow rate and volume were 0.05 L/min and 2.0 L, respectively, and the highest removal rate of Ca2+ from the leachate was about 90%. The maximum removal rate of CO2 from landfill gas could reach 95%, and the CO2 content of the post-reaction gas was as low as 1.74% (volume percentage). The scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis showed that the precipitate was spherical and mainly contained inorganic substances such as CaCO3, MgCO3, Ca(OH)2, Mg(OH)2, and SiO2. The study showed that, before the leachate was piped, the Ca2+ could be removed using the raw landfill gas, thereby reducing the potential for the formation of precipitation clogging in the pipeline. This study also provides new ideas for upgrading landfill gas to achieve a renewable-energy utilization plan, and reduces greenhouse gas emissions by reducing CO2 emissions from landfills.

Transport and Barrier Functions in Rainbow Trout Trunk Skin Are Regulated by Environmental Salinity.

The mechanisms underpinning ionic transport and barrier function have been relatively well characterised in amphibians and fish. In teleost fish, these processes have mostly been characterised in the gill and intestine. In contrast, these processes remain much less clear for the trunk skin of fish. In this study, we measured barrier function and active transport in the trunk skin of the rainbow trout, using the Ussing chamber technique. The effects of epithelial damage, skin region, salinity, and pharmacological inhibition were tested. Skin barrier function decreased significantly after the infliction of a superficial wound through the removal of scales. Wound healing was already underway after 3 h and, after 24 h, there was no significant difference in barrier function towards ions between the wounded and control skin. In relation to salinity, skin permeability decreased drastically following exposure to freshwater, and increased following exposure to seawater. Changes in epithelial permeability were accompanied by salinity-dependent changes in transepithelial potential and short-circuit current. The results of this study support the idea that barrier function in rainbow trout trunk skin is regulated by tight junctions that rapidly respond to changes in salinity. The changes in transepithelial permeability and short circuit current also suggest the presence of an active transport component. Immunostaining and selective inhibition suggest that one active transport component is an apical V-ATPase. However, further research is required to determine the exact role of this transporter in the context of the trunk skin.

Impact of Reservoir Heterogeneity on Diluted Geothermal Brine Reinjection

Many geothermal plants have been shut down due to reinjection problems with the heat-depleted brine. In Denmark, only one out of three plants that extract heat from a geothermal fluid distributed to the district heating system is still working. In general, the large salinity of heat-depleted geothermal brines can be used to produce electricity with the help of turbines and generators through an osmotic power unit known as a SaltPower plant. Harnessing more energy out of the reinjection of geothermal brines is feasible without compromising the overall reservoir assurance when the iron is kept under control. This study is an attempt to determine the feasibility of the reinjection of a diluted geothermal brine with ethylenediaminetetraacetic acid (EDTA) into homogeneous and heterogeneous sandstone rocks. The results from the coreflooding experiments show an improvement in the rock properties both in porosity and permeability for homogeneous and heterogeneous rocks. EDTA not only avoids the precipitation of Fe(III) oxides inside the porous media but can also be used for scale removal and matrix acidizing in geothermal reservoirs.

Potential of nanocomposites of zero valent copper and magnetite with Eleocharis dulcis biochar for packed column and batch scale removal of Congo red dye

The current study is the first attempt to prepare nanocomposites of Eleocharis dulcis biochar (EDB) with nano zero-valent Copper (nZVCu/EDB) and magnetite nanoparticles (MNPs/EDB) for batch and column scale sequestration of Congo Red dye (CR) from synthetic and natural water. The adsorbents were characterized with advanced analytical techniques. The impact of EDB, MNPs/EDB and nZVCu/EDB dosage (1–4 g/L), pH (4–10), initial concentration of CR (20–500 mg/L), interaction time (180 min) and material type to remove CR from water was examined at ambient temperature. The CR removal followed sequence of nZVCu/EDB > MNPs/EDB > EDB (84.9–98% > 77–95% > 69.5–93%) at dosage 2 g/L when CR concentration was increased from 20 to 500 mg/L. The MNPs/EDB and nZVCu/EDB showed 10.9% and 20.1% higher CR removal than EDB. The adsorption capacity of nZVCu/EDB, MNPs/EDB and EDB was 212, 193 and 174 mg/g, respectively. Freundlich model proved more suitable for sorption experiments while pseudo 2nd order kinetic model well explained the adsorption kinetics. Fixed bed column scale results revealed excellent retention of CR (99%) even at 500 mg/L till 2 h when packed column was filled with 3.0 g nZVCu/EDB, MNPs/EDB and EDB. These results revealed that nanocomposites with biochar can be applied efficiently for the decontamination of CR contaminated water.

Experimental study of crystallization fouling by calcium carbonate: Effects of surface structure and material

Mitigation of crystallization fouling on heat transfer surface is crucial for developing highly efficient desalination techniques, because the tenacious and porous crystal layer can drastically deteriorate system efficiency. Surface modification is a potential approach to decrease scale formation and promote crystal removal, but some of the mechanisms between crystallization and substrate properties are still not fully understood. In this study, we use dual-angle microscopic visualization and image processing to quantify three-dimensional crystallization behavior and analyze the impact of surface structure and material. The transition of crystal size and distance with roughness and wettability are identified from statistical analysis. The determination of crystal porosity and effective thermal conductivity is enabled by visualized geometry and measured deposition mass. This study shed lights on potential strategies of surface modification to mitigate scaling in desalination by enhancing scale removal and localizing crystal growth.