Reduction In Salinity Research Articles

Desalinization of degraded soils by atmospheric precipitation and Biosolvent for saving water resources

In the Syrdarya region of Uzbekistan, the influence of atmospheric precipitation on changes in the degree of salinity and chemical composition of the upper 30 cm soil layer was studied. Experiment options: 1 - loosening the soil to a depth of 70 cm, 2 - loosening, followed by soil treatment with preparation containing polymaleic acid. A decrease in the degree of soil salinity by 7 - 8 dS/m has been established with the help of only 302 mm of precipitation, without water wasted for leaching. The decrease in soil salinity was: according to EU, 56% - in option 2, and 52% - in option 1. According to TDS, the salinity reduction was: - 61 and 52%, according to SO “4. - 58 and 47%. The content of calcium in the variant with the use of Biosolvent decreased by 48%, and in the control variant, it increased by 15%. It has been estimated that with a decrease in salinity from 16 to 8 dS/m, a possible increase in the yield of a salt-tolerant barley crop by 1.6 t/ha is possible. Taking into account the costs of loosening and tillage with the preparation, the net income of the farmer can be $480/ha.

Potentialities of plant based hybrid wetland systems for the treatment of household waste water using Canna indica, Agave americana, Pistia stratiotes and Tagetes erecta

The ever increasing population is generating large amount of waste water and it is increasing with time especially with the higher per capita consumption of water in the country. Besides, the ample amount of energy required by the conventional water treatment methods is hampering the economic viability of the procedure. This asks for newer and efficient low cost nature based water treatment system which along with cost takes into consideration the sustainability of the ecosystem. In this study a hybrid plant based wetland system consisting of four plant species were used to treat the household grey water. Agave americana and Tagetes erecta were used in constructed wetland, Canna indica plant was used in floating raft wetland and Pistia stratiotes in oxidation pond for a period of 24 h retention to know the efficiency. The pollution reduction was analysed after 2 h, 4 h, 6 h, 8 h and 24 h hydraulic retention period (HRT) in all these systems. Three parameters basically BOD, COD and salinity reduction were checked as an initial research to know the viability. The results showed that BOD reduction ranged from 6.67 to 41.18% in various systems within 24 h of retention, whereas COD showed a reduction range of 5.32–35.47% and salinity exhibited a reduction range of 6.93–21.49% based on the different systems.

Departures from the archetypal deltaic ichnofacies

Abstract Recent work has focused on erecting new Seilacherian ichnofacies for depositional environments subject to recurring temporal and spatial variations in physico-chemical stress. In marine deltaic settings, these correspond to the Phycosiphon Ichnofacies for mudstone-dominated prodeltaic deposits and the Rosselia Ichnofacies for sandstone-dominated delta-front successions. The archetypal expressions of these ichnofacies, however, are founded on mixed process (wave- and river-influenced) systems, because the juxtaposition of ambient marine conditions during periods of prolonged wave energy with rapid deposition and physico-chemically stressed conditions during heightened fluvial discharge best expresses the deltaic signal. As deltaic settings shift towards end-member processes (e.g. river domination, wave domination and tide domination), or towards mixed-process conditions other than river and wave influence, the resulting ichnological suites and bioturbation fabrics depart from the recently published archetypes. Using selected studies of marine deltaic deposits, predictable departures from the archetypes can be recognized on the basis of these changing processes and their associated physico-chemical stresses. River-dominated delta deposits and tide-dominated delta successions display the greatest deviation from the published archetypes. River-dominated examples show elevated deposition rates, periods of salinity reduction, slumping and dewatering, elevated water turbidity, flood-induced sediment gravity flows and hypopycnal-generated fluid mud. As a result, river-dominated successions are largely devoid of bioturbation. Evidence of marine conditions is commonly restricted to isolated occurrences of dwelling structures such as Arenicolites , Ophiomorpha or Rosselia in sandstone, and Chondrites , Phycosiphon or Zoophycos in mudstone beds, particularly in prodeltaic intervals. Tide-dominated deltaic successions are markedly heterolithic and typified by highly mobile substrates manifested by incrementally migrating asymmetric bedforms and abundant fluid mud. Such settings are also prone to marked changes in salinity and shifts in the position of the turbidity maximum zone. Successions typically show low intensities of bioturbation and sporadically distributed burrows, as well as deposit-feeding structures, deeply penetrating dwelling structures or fugichnia. Many trace fossil suites consist entirely of facies-crossing elements, making assignment to an ichnofacies impossible. Storm flood-dominated deltaic successions are characterized by tempestites that are typically interstratified with river flood-induced sediment-gravity flow deposits and/or mantled by largely unburrowed mudstone drapes derived from hypopycnal plumes associated with river floods. Where these storm flood cycles are interstratified with ambient fairweather beds, assignment to the archetypal deltaic ichnofacies is straightforward. However, as storm beds become increasingly erosionally amalgamated, the preservation potential of the fairweather beds is reduced and the resulting trace fossil suites are biased towards those recording opportunistic colonization of the event beds. The presence of mudstone layers with low bioturbation intensity (BI) containing small numbers of ichnogenera positively correlated with marine conditions (e.g. Chondrites , Phycosiphon and/or Zoophycos ) may be the only evidence that the suites should be assigned to one of the deltaic ichnofacies. Wave-dominated deltas lacking significant storm influence are typically challenging to differentiate from their archetypal strandplain shoreface counterparts and, correspondingly, the resulting trace fossil suites are broadly comparable to the archetypal Cruziana and Skolithos ichnofacies. Most of the preserved record of wave-dominated delta successions is related to fairweather ambient conditions, and so facies typically show high BI values and uniformly distributed bioturbation. Key to recognizing that the suites should be assigned to one of the deltaic ichnofacies is the presence of rare river-generated mudstone and sandstone beds that display evidence of physico-chemical stress and/or the paucity of domichnia typical of suspension-feeding organisms. In most delta types, the prodeltaic facies are most readily discerned to contain trace fossil suites of the Phycosiphon Ichnofacies, owing to the higher preservation potential of all depositional processes, including marine fairweather beds, river-supplied hyperpycnites and other sediment gravity flow deposits, tempestites and fluid mud derived from river flood-related hypopycnal plumes. Assignment of trace fossil suites to the Rosselia Ichnofacies requires some record of the fairweather conditions, which are generally diminished in river-, tide- and storm-dominated successions. The dominance of structures positively correlated to deposit-feeding ethologies at the expense of those attributed to suspension-feeding strategies may point to elevated water turbidity and assignment of the suite to the Rosselia Ichnofacies. However, in many cases, the ichnological suites of delta fronts are so depauperate that assignment to an ichnofacies is problematic and should be avoided.

Permeability decline by fines migration near sand control screens in steam assisted gravity drainage: A numerical assessment

The near-wellbore permeability loss caused by the release and migration of naturally fine particles impairs the well productivity in oil reservoirs. The damage would be intensified in the presence of restrictions such as sand control screens due to retardation and accumulation of fine particles resulting from flow convergence and high volumetric flux.This study focuses on the experimental investigation and mathematical modeling of the permeability impairment near the sand control screens under a representative fines migration process for the SAGD well conditions. For this purpose, the single-phase flow experiments were conducted on unconsolidated sand packs in a sand retention testing (SRT) setup. The testing used different sand screens and considered the chemical effect of the fines migration process and different salinity for the saturating brine and flowing fluid. A 3D numerical model incorporating governing fluid and particle transport equations in porous media and an empirical permeability loss equation was established to simulate the fines migration process.The results show that the sand screens with a low open flow area and narrow aperture size cause higher permeability loss under the same flow conditions. Higher salinity reduction yields higher mobilized fines concentration, causing high near-screen permeability loss. For the salinities above 800 ppm, no significant pressure drops were observed. Furthermore, changing salinity to deionized water (DI) caused almost complete plugging of the sand pack, masking the flow performance of the sand control screen. A good match was obtained between the measured and calculated dimensionless pressure drops from the experimental and numerical models. The calibrated model could accurately enough predict the dimensionless pressure drops for the near-screen interval. It was confirmed that the porous medium's model parameters were nearly independent of the sand screen. However, different results were obtained for different salinities, confirming the 'parameters' dependency on not just porous medium but also fluid properties.

Surface-active compounds induce time-dependent and non-monotonic fluid-fluid displacement during low-salinity water flooding

Hypothesis: In a porous medium saturated with oil (containing oleic surfactant) and saline water, salinity reduction alters the thermodynamic equilibrium and induces spatial redistribution of surfactants, changing the local fluid configuration. During fluid–fluid displacement, this local change reshapes global fluid flows, and thus results in improved oil displacement.Experiments: We performed microfluidic experiments in a centimeter-long pore-network model with a fracture and a dead-end model to observe both the macroscale flows and microscopic fluid configuration evolution. Water with different salinities and model oils with different surfactant concentrations are used.Findings: When oil contacts low salinity water, we observe (1) the solid surface becomes more water-wet, and (2) water-in-oil emulsion spontaneously emerges near the oil–water interface. At the macroscale, the fluid distribution remains unchanged in short term but dramatically changes after tens of hours, which appears as improved oil recovery. Two modes are identified during fluid redistribution: gradual imbibition and sudden collapse. The displacement efficiency is a non-monotonic function of surfactant concentration. This is attributed to the interplay between two opposing effects by adding surfactant: (1) enhancing initial hydrophobicity which negatively affects the displacement, and (2) allowing stronger oil swelling which is beneficial for displacement.

Impact of Short-Term Cultivation on Some Selected Properties of Sandy Soil in an Arid Environment

Soil management is recognized to have an impact on soil quality attributes. Depending on the management approach, this impact can either degrade or improve soil quality. There is a severe shortage of information on the impacts of cultivation on sandy soil properties in arid desert regions. Therefore, the objective of this study was to investigate the short-term cultivation effects (5 years) on the properties’ changes of coarse-textured soil in an arid desert region in western Assiut Governorate, Egypt. The current study was conducted on soils sampled at four depth intervals, namely 0–10, 10–20, 20–30, and 30–40 cm, from both cultivated and uncultivated soils, using a systematic sampling grid (10 × 10 m), to investigate the potential impacts of the cultivation process on six soil attributes. Each land use was represented by an area of 0.5 ha (50 × 100 m). A total of 160 composite soil samples (at all depths) were collected from both soils and analyzed for their physical and chemical properties, employing standard laboratory procedures. The data were statistically and geostatistically analyzed to compare the results and map the spatial distributions of the selected soil properties. The results revealed that cultivation had a considerable positive impact on most of the properties of cultivated soil compared to those of uncultivated soil (virgin land). The findings also showed that the available phosphorus levels in cultivated soil were higher than in virgin soil by 16, 9, 8.5, and 6 folds, with increases in organic matter content of 16.8, 12.4, 11.9, and 7.9 times at depths of 0–10, 10–20, 20–30, and 30–40 cm, respectively. Furthermore, compared to virgin soil, cultivated soil exhibited a salinity reduction of −8.9%, −56.4%, −66.3%, and −71.8%, at depths of 0–10, 10–20, 20–30, and 30–40 cm, respectively. Moreover, some other properties of the cultivated soil improved, particularly in the surface soil layers, such as pH reduction, CaCO3 decline, and CEC increase, while the soil texture grade did not change. Therefore, continuous monitoring of the effects of diverse soil management strategies in the short term assists in the understanding of the ongoing changes in soil physical and chemical characteristics, which is critical for maintaining satisfactory soil quality and sustainable soil productivity in arid lands.

Geology, molybdenite Re-Os age, H-O-S-Pb isotopes, and fluid inclusion features of the Maodeng Mo-Bi-Sn-Cu deposit, Inner Mongolia

Maodeng deposit is a large-sized Mo-Bi-Sn-Cu deposit located in the Xinlinhot of Inner Mongolia in the southern segment of the Great Xing’an Range. The ore-forming elements in the deposit are found in the volcanic breccia of Lower–Middle Permian Dashizhai Formation and granite porphyry of the Alubaogeshan complex, constituting distinct regional mineralization zones such as hydrothermal vein-type of Sn-Cu orebodies in the upper parts and stockworks, veinlets and disseminated-type of Mo-Bi orebodies in the lower parts. This paper has conducted an integrated study using a comprehensive field survey, molybdenite Re-Os age, fluid inclusion, and isotopic (O, H, S, and Pb) analyses. The mineralization in the deposit can be divided into four stages, which are molybdenite-native bismuth-quartz (stage I), cassiterite-wolframite-topaz-quartz (stage II), chalcopyrite-sphalerite-galena-fluorite-sericite-quartz (stage III) and stibnite-pyrite-quartz-fluorite (stage IV). The Re-Os isochron age of four molybdenite samples was estimated as 139.2 ± 3.9 Ma, indicating the deposit was formed during the Early Cretaceous. The Maodeng deposit is characterized by three kinds of fluid inclusions (FIs): liquid-rich two-phase, vapor-rich two-phase, and daughter mineral-bearing three-phase FIs. The homogenization temperatures for the FIs of stages I through IV are 292–387 °C, 222–333 °C, 172–252 °C, and 122–197 °C, with calculated salinities of 4.2–43.6 wt%, 2.1–38.9 wt%, 1.9–33.6 wt% and 0.7–5.1 wt% NaCl equiv., respectively, showing the gradual reduction in temperature and salinity of hydrothermal fluids. Hydrogen and oxygen isotopic data of quartz indicate that the dominant origin of the ore-forming solutions from deep granitic intrusions followed by their dilution by limited meteoric water. The sulfides have δ34S values ranging from − 6 ‰ to − 0.49 ‰, and have 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios similar to those of K-feldspars from the Alubaogeshan pluton, suggesting the primary origin of ore-forming materials of the Maodeng deposit are magmatic. Molybdenite and native bismuth may precipitate primarily by fluid boiling, chalcopyrite could deposit mainly by fluid mixing, and cassiterite precipitate mainly through fluid boiling and mixing.

Development of models for sustainable green mussel cultivation under climate change events

This research developed a green mussel cultivation model to assist sustainable production for farmers under climate change events. The model consists of 4 sub-models: mussel growth, phytoplankton population, the effect of seawater quality on mussel density, and the influence of atmospheric parameters on seawater quality. The integrated model was constructed by STELLA software and was calibrated with field observation data. The model was employed to simulate the impact of climate change on mussels based on the Intergovernmental Panel on Climate Change: The Fifth Assessment Report (IPCC AR5) projection. Results demonstrated that mussel production varied due to differences in the available phytoplankton, the initial mussel weight, the cultivation period, the air temperature, and the rainfall pattern. The model simulations showed that under the greater radiative forcing scenario (Representative Concentration Pathways: RCPs), higher rainfall and air temperatures resulted in salinity reduction and thermal stress on green mussels. Consequently, mussel production was forecasted to decline over time. The simulations also revealed that during extreme weather events, low mussel density, high aeration, and being far from freshwater discharge could avoid mass mussel mortality. Using the results of the developed model, an appropriate cultivation period can be forecasted. However, it depends on the site-specific climate pattern in each cultivation area. Results can be employed as a climate change adaptation tool for mussel farmers. Finally, the information can assist other researchers interested in sustainable mussel cultivation under extreme events.

Steroidogenic Effects of Salinity Change on the Hypothalamus-Pituitary-Gonad (HPG) Axis of Male Chinese Sea Bass (Lateolabrax maculatus).

As lower vertebrates, teleost species could be affected by dynamic aquatic environments and may respond to environmental changes through the hypothalamus–pituitary–gonad (HPG) axis to ensure their normal growth and sexual development. Chinese sea bass (Lateolabrax maculatus), euryhaline marine teleosts, have an extraordinary ability to deal with a wide range of salinity changes, whereas the salinity decrease during their sex-maturation season may interfere with the HPG axis and affect their steroid hormone metabolism, resulting in abnormal reproductive functioning. To this end, in this study, 40 HPG axis genes in the L. maculatus genome were systematically characterized and their copy numbers, phylogenies, gene structures, and expression patterns were investigated, revealing the conservation of the HPG axis among teleost lineages. In addition, freshwater acclimation was carried out with maturing male L. maculatus, and their serum cortisol and 11-ketotestosterone (11-KT) levels were both increased significantly after the salinity change, while their testes were found to be partially degraded. After salinity reduction, the expression of genes involved in cortisol and 11-KT synthesis (cyp17a, hsd3b1, cyp21a, cyp11c, hsd11b2, and hsd17b3) showed generally upregulated expression in the head kidneys and testes, respectively. Moreover, cyp11c and hsd11b2 were involved in the synthesis and metabolism of both cortisol and 11-KT, and after salinity change their putative interaction may contribute to steroid hormone homeostasis. Our results proved the effects of salinity change on the HPG axis and steroidogenic pathway in L. maculatus and revealed the gene interactions involved in the regulation of steroid hormone levels. The coordinated interaction of steroidogenic genes provides comprehensive insights into steroidogenic pathway regulation, as well as sexual development, in teleost species.

Produced water treatment using microemulsion formulated with vegetable oil-based surfactant

The presence of produced water is common in oil production. In certain production stages, the volume of produced water exceeds that of oil. Pretreatment is necessary before the disposal or reinjection of produced water into wells because it is harmful to the environment owing to the high oil and grease contents (OGC), salinity, and other factors. This study proposes a produced water treatment using microemulsions (ME) with vegetable oil-based surfactants (S), with the aim of reducing two main factors, OGC and salinity. The decision to use a vegetable oil-based surfactant as an alternative to a petroleum-based surfactant was made to reduce the negative effects of the overall process on the environment. Coconut soap, the surfactant used in the formulated ME, was selected after testing a variety of vegetable oil-based surfactants. The other components used in the ME formulation were 2-butanol as a co-surfactant (C), pine oil as the oil phase, and saline water at 2 % NaCl as the water phase. The ME point used in the water treatment was defined by D-optimal mixture planning, composed of 85 % C/S, 2.5 % oil phase, and 12.5 % water phase, with a C/S ratio of 10. In addition, we used a complete factorial experimental design with combinations of three variables (time, temperature, and microemulsion percentage), and repetition of the central point to select the greatest reduction in OGC and salinity. According to the results, OGC reduction values ranged from 89.15 % to 95.43 %, with the real OGC values ranging from 16.98 mg·L−1 to 7.15 mg·L−1. These values are within the limits established by environmental agencies, CONAMA, US EPA, and the OSPAR Commission, for the disposal of produced water in the sea. In addition, salinity reduction varied from 38.02 % to 46.8 %, with real salinity decreasing from 36,223.53 mg·L−1 to 31,217.65 mg·L−1. Therefore, it can be said that using a vegetable oil-based and biodegradable surfactant in the microemulsion formulation for the treatment of produced water is as effective in the reduction of OGC and salinity as petroleum-based surfactants, which are more harmful to the environment.

Emerging biological archives can reveal ecological and climatic change in Antarctica.

Anthropogenic climate change is causing observable changes in Antarctica and the Southern Ocean including increased air and ocean temperatures, glacial melt leading to sea-level rise and a reduction in salinity, and changes to freshwater water availability on land. These changes impact local Antarctic ecosystems and the Earth's climate system. The Antarctic has experienced significant past environmental change, including cycles of glaciation over the Quaternary Period (the past ~2.6 million years). Understanding Antarctica's paleoecosystems, and the corresponding paleoenvironments and climates that have shaped them, provides insight into present day ecosystem change, and importantly, helps constrain model projections of future change. Biological archives such as extant moss beds and peat profiles, biological proxies in lake and marine sediments, vertebrate animal colonies, and extant terrestrial and benthic marine invertebrates, complement other Antarctic paleoclimate archives by recording the nature and rate of past ecological change, the paleoenvironmental drivers of that change, and constrain current ecosystem and climate models. These archives provide invaluable information about terrestrial ice-free areas, a key location for Antarctic biodiversity, and the continental margin which is important for understanding ice sheet dynamics. Recent significant advances in analytical techniques (e.g., genomics, biogeochemical analyses) have led to new applications and greater power in elucidating the environmental records contained within biological archives. Paleoecological and paleoclimate discoveries derived from biological archives, and integration with existing data from other paleoclimate data sources, will significantly expand our understanding of past, present, and future ecological change, alongside climate change, in a unique, globally significant region.

Growth, health status and gut microbiota of the scalloped spiny lobster (Panulirus homarus) at different salinities

The scalloped spiny lobster (Panulirus homarus) is a valuable species for aquaculture due to its high commercial value. However, limited information is available regarding the effect of environmental parameters on aquaculture of P. homarus. This study investigated the growth performance, health status and gut microbiota of P. homarus juveniles cultured at salinity 35 (control), 25, and 15 for 4 weeks. Compared to the control, the survival, weight gain, condition factor and haemolymph cell number were significantly reduced in P. homarus at salinity 15, while no significant differences were found in P. homarus at salinity 25. Compared with the control group, the antioxidant indices including total antioxidant capacity, superoxide dismutase and glutathione peroxidase in the 15 and 25 salinity groups were significantly increased, and malondialdehyde increased significantly only at salinity 15. Compared with salinity 35, salinity 15 significantly changed the structure of gut microbiota, increased within-habitat and between-habitat diversity, and increased the abundance of opportunistic pathogens Photobacterium and Vibrio. Unsurprisingly, the functions of the gut microbiota were mainly enriched in the metabolism pathway of the KEGG-level 1, and the KEGG-level 2 pathways with an enrichment abundance of >3000 were all in the metabolism pathway. Interestingly, compared with the salinity of 35, the antibiotic synthesis pathway was significantly inhibited, while the pathways related to bacterial life were significantly enhanced in the salinity 15. In conclusion, salinity changes affect growth, antioxidant capacity, and gut microbiota composition of P. homarus, and the effects of large-scale reductions in salinity (e.g., salinity 15) are generally detrimental.

Rain Impacts on the Surface Atmosphere and Upper Ocean in the Central Equatorial Pacific

Abstract The impacts of rainy days (>24 mm) on the physics of the surface atmosphere and upper ocean are characterized in the central Pacific Ocean (140°–170°W) on the equator, where deep-cycle turbulence substantially influences the sea surface temperature and air–sea heat flux on diurnal and longer time scales. Here, rainfall is relatively weak on average (1–3 mm day−1), and enough rain to substantially alter the diurnal cycle of upper-ocean buoyancy only occurs on the order of once in 100 days, albeit more frequently to the west and during El Niño and boreal winter. Rainy days are associated with multiple systematic changes in the surface atmosphere, but the freshwater and the reduction in daily downwelling shortwave radiation (by ∼50 W m−2) are codominant and drive systematic changes in the ocean during and the day after the rainy day. These two drivers explain ensemble average reductions in the upper-ocean salinity (−0.12 psu at 1 m) and temperature (−0.16°C at 1 m) and increases in buoyancy (+0.0005 m s−2 at 1 m), which are typically confined to a shallow fresh/warm mixing layer on the order of 10 m thick in the daytime. At deeper depths, the intrinsic ocean temperature, salinity, and velocity variability make it challenging to extract an ensemble average response to rainy days in observations, but some examples from observations and large-eddy simulations suggest that rainfall can significantly reduce the vertical extent and heat flux in the deep-cycle turbulence, although the bulk energetics and buoyancy flux of the turbulence are not necessarily modified by rain. Significance Statement Rain significantly impacts social and ecological systems in many ways that are readily apparent in populated areas, but the impacts of rain over the ocean are not as well known. In this paper, sustained in situ observations over decades and highly resolved numerical simulations of ocean turbulence during a few rain events are used to characterize the impacts of rainy days on the surface–atmosphere and upper-ocean physics in the center of action of El Niño in the central equatorial Pacific. These results contribute to broader efforts to observe, understand, and accurately model the surface atmosphere, the upper ocean, and air–sea interaction in the central Pacific and thereby improve long-range weather and climate observations and predictions.

Algal immobilization as a green technology for domestic wastewater treatment

wastewater treatment technology is an important issue because of numerous organic and inorganic impurities in municipal, industrial, and agricultural waters. Different systems of wastewater treatment used the microorganisms for the removal of organic materials, most species of algae represent promising biosystems for treating of wastewater by transformation or direct uptake of pollutants and improving the purification performance of bacterial systems. This work aimed to study the efficiency of immobilization technology using immobilized cells of green algae Chlorella vulgaris in the treatment of domestic wastewater. Some physical and chemical characteristics of domestic wastewater were examined and the percentage of treatment efficiency with free and immobilized cells of alga were compared. The results of the study presented high reduction of EC, salinity, TDS, total alkalinity, hardness, calcium, and chloride with slight induction of pH values to the basal side after treatment with free and immobilized algae. After (3,5,7) days of treatment with free microalgae and immobilized microalgae, the recorded value of wastewater had been eliminated to (2.09, 2, 1.8) μs/cm and (2.36, 1.27, 1.07) μs/cm of EC; (689, 580, 520) mg/L and (620,520,489) mg/L of the total hardness; (320, 244, 220) mg/L and (300, 244, 204 ) mg/L of the calcium; (420, 369, 309) mg/L and (400, 340, 289) mg/L of chloride, respectively, while pH value increased to (8.6, 8.7, 8.6) after treated with free microalgae. The results showed high efficiency of mobilized algae compared with free algal cells in reducing many physical and chemical parameters and the immobilized algal cell technique is useful as tools in the treatment process of wastewater.

Facilitating proton transport by endowing forward osmosis membrane with proton conductive sites in osmotic microbial fuel cell

A major challenge of the osmotic microbial fuel cell (OsMFC) application is the sluggish proton transport from anode to cathode. As a result, an extra overpotential is caused by the remarkable catholyte alkalinization and anolyte acidification. Thus, the efficiency of water extraction and biodegradation of organic pollutants are adversely affected simultaneously. To address this issue, proton conductive sites were introduced into the forward osmosis (FO) membrane by importing sulfonic acid radical groups. The results demonstrated that the proton transport flux improved after FO membrane modification. The OsMFC system with an optimal FO membrane achieved a 58.86 % reduction in artificial seawater salinity, enhanced the volume of water extraction by 61.90 %, increased the chemical oxygen demand removal efficiency by 6.39 %, and improved the current density by 16.56 %. In particular, the maximum power density of the optimized OsMFC (7.08 ± 0.42 W·m−3) was enhanced by 108.85 % and 60.18 % compared with those with Nafion and pristine FO membrane, respectively. Meanwhile, the mechanism of proton transport in the OsMFC system has been elucidated. The proton migration was reinforced under the synergistic effect of improved water flux and electromigration derived from internal electric field. This method to mitigate the catholyte pH through self-buffering in situ is green and economical. This will further open a novel avenue for OsMFC application in large-scale actual wastewater treatment.

A process for CO2 capture and brine salinity reduction through reaction with potassium hydroxide: A multi-stage evaluation

Solvay and modified Solvay processes are facing a major challenge in reducing brine salinity to a level suitable for agriculture and industry. This challenge arises as a result of competing reactions and mixing limits between CO2 gas and brine. Another challenge is the high solubility of sodium bicarbonate (NaHCO3), which results in a low overall desalination efficiency. Previous studies established the effectiveness of a modified Solvay process based on potassium hydroxide (KOH). The first objective of this study is to evaluate a multi-stage treatment for a modified Solvay process on the basis of potassium hydroxide (KOH) to achieve an additional reduction in ion removal from high-salinity brines and an increase in CO2 capture as compared to previously obtained under optimal operating conditions. Three different methods were investigated. The first method evaluated the effectiveness of adding ammonium bicarbonate (NH4HCO3) in reducing the solubility of NaHCO3. Even though the Na+ and Cl− concentrations were reduced by 56.2% and 40%, respectively, the total CO2 uptake slightly improved by 1.2% (67.8 g CO2/1000 ml of treated brine). In the second method, the addition of extra KOH in subsequent stages was investigated to overcome the pH reduction observed in the first method. There was an ∼ 47.3% improvement in CO2 uptake from the first method. Furthermore, the percentages of Na+ and Cl− removal were increased to 65% and 64.5%, respectively. In the third method, the recovery of Ca2+ and Mg2+ was approximately 76.3% and 94.6%, respectively, following the pre-treatment step (filtration), followed by the same stages as in the second method. Reducing these ions decreased the competitive reactions and thus increased CO2 solubility and reactivity with KOH, resulting in higher cumulative CO2 uptake from all stages to 108.2 g CO2/1000 ml, which was 8.3% more than the second method. Additionally, solid products were characterized using scanning electron microscopy, X-ray diffraction, FTIR and Raman analysis. Finally, the dynamic behaviour of the reactor was evaluated using step changes in the inlet gas and liquid flow rate. The results are promising in terms of the reactor system's adaptability to large-scale processes.

Enhanced oil recovery in carbonate rocks using seawater spiked with copper chloride: Imbibition experiments

It is widely accepted that oil recovery during waterflooding can be improved by modifying the composition of the injected brine, typically by depleting the total salinity or altering potential determining ions (PDI) such as: Ca2+, Mg2+, and SO42− concentration. Numerous laboratory experiments and field tests have demonstrated this effect in both clastic and carbonate rock Samples and reservoirs. However, some authors have found alternative ions, such as phosphate (PO42−) and borate (B(OH)4-) which, in some cases, presented additional recovery and have thus opened the discussion for potential alternative ions to enhanced oil recovery. With this in mind, copper ion's potential for enhanced oil recovery (EOR) was studied, combining different conditions usually employed on smart water experiments, such as depleting the total salinity and removing the PDI to highlight the real effect of copper on additional oil recovery. The investigation was carried out with Brazilian pre-salt reservoir Samples in imbibition experiments using Amott cells at ambient pressure and 63 °C. The evaluation of the copper effect on oil recovery for coreflooding was proved in a previous paper by Bernadinelli et al. (2021), however the analysis with imbibition experiments in this study aim to clarify the effect of copper on the capillary pressure, by analyzing the eventual additional oil production. These Samples were prepared and aged, and the oil production was monitored during the experimental time. The experiments were carried in four sequences to evaluate the effect of copper on oil recovery, consisting first of salinity reduction from 0% of sodium chloride to 100% of the original amount in the seawater (SW), followed by the removal of PDI salts, the study of the production mode (secondary or tertiary), and the analysis of the copper chloride concentration on the final recovery. The results using copper at the secondary recovery showed remarkable increases (from 6.3% to 10.0%) of the original oil in place (OOIP) compared to the oil recovered from the formation water (FW). In tertiary mode, the best recoveries occurred at salinities between 8 and 18 kppm and copper chloride (1 g/L), and presented increasing recoveries 3.9%, 5.8%, and 9.3% of OOIP. This work presents an initial investigation on the use of copper as an active ion for the smart water effect and sheds light on its effect on both secondary and tertiary modes for strategies of recovery that use soaking methods and also for fractured reservoirs.

Ferrate-pretreated directional solvent extraction for hydraulic fracturing produced water: Technical and economic feasibility studies

Produced water (PW) generated from hydraulic fracturing operations contains varying amounts of crude oil, sand and dissolved ions, and is typically characterized as hyper-brine. It is often untreatable by existing desalination technologies. This study presents using the directional solvent extraction (DSE) technique to desalinate multiphasic, synthetic produced waters (SPW) using diisopropylamine (DIPA) as the extraction solvent and a ferrate pretreatment method. DSE with ferrate pretreatment achieved an average solvent efficiency of 0.25, 0.13 and 0.03 mL water/g solvent at 1 M, 2 M and 4 M salinity, respectively. The water extraction, turbidity reduction and salinity reduction efficiency were better for DSE with ferrate-pretreatment than compared to DSE alone. DSE's salt rejection rates in the product water were consistently over 95 %, while turbidity reduction was dependent on ferrate dosage used for pretreatment. This process costs an estimated $1.23 per m3 of water extracted from a 4 M brine for a single-pass operation with 95 % heat recoveries.

Osmotic urine fuel cell to recover water, energy, and nutrients along with salinity reduction

Osmotic urine fuel cell to recover water, energy, and nutrients along with salinity reduction

Synergistic effect of low saline ion tuned Sea Water with ionic liquids for enhanced oil recovery from carbonate reservoirs

In recent decades, low salinity water flooding (LSWF) has gained much attention from both the industry and academia due to its effectiveness in oil recovery. Many efforts are still going on to harness the effect of LSWF combined with chemical enhanced oil recovery (CEOR). However, studies identifying Ionic Liquids (ILs) as potential candidates for CEOR with LSWF are not available in the literature. This study aims to evaluate the synergistic effect of ILs with varying chain lengths ([C8mim] [BF4], [C10mim] [BF4], [C12mim][BF4]) with the low saline ion tuned seawater (ITSW) for enhanced oil recovery (EOR) from carbonate reservoirs. A comprehensive analysis viz. stability and compatibility of ILs, IFT, zeta potential, contact angle, and adsorption analysis were performed to establish the mechanisms. Finally, oil recovery potential was quantified by core flooding. ILs showed a better synergistic effect with ITSW than SW. The IFT value was found to be decreasing with increasing chain length and reduction in salinity. ILs with ITSW demonstrated a strong ability to alter the wettability of rock surfaces to less oil-wet conditions. Zeta potential values turned towards the positive side with adding ILs at the oil/brine and rock/brine interfaces. In addition, ILs have shown significantly less adsorption density in ITSW than SW at the simulated reservoir temperature of 90 °C. IL having the longest chain length ([C12mim] [BF4]) showed superior properties compared to other ILs and reported an incremental recovery of 12% of original oil in place (OOIP) with low saline ITSW. The primary mechanisms involved for better performance of [C12mim] [BF4] with ITSW are calcite dissolution, the interplay of potential determining ions, and enhanced ion pair formation.