Showing papers on "Brine published in 2021"

A review of resource recovery from seawater desalination brine

Abstract: In order to address freshwater scarcity, seawater desalination technologies have been widely studied in recent years. However, the disposal of desalination brine which contains an even higher concentration of salts than seawater can potentially damage the surrounding environment. Therefore, alternative approaches aiming to recover valuable resources from desalination brine have been conducted. Three resources that can be recovered have been studied in this paper, which are minerals, freshwater and energy. The techniques to recover minerals can be divided into pressure-driven techniques, thermal-driven techniques, electro-driven techniques and other techniques. The water recovery techniques employ mainly membrane/thermal integrated hybrid processes, while the energy recovery techniques such as pressure retarded osmosis (PRO) and reverse electrodialysis (RED) utilize the salinity gradient energy (SGE) to generate energy. The valuable mineral products have also been reviewed in this paper in terms of recovery methods, performance of processes and product quality. The reviewed products are sodium salts (NaCl, NaOH, Na2SO4), lithium salts (LiCl, Li2CO3), magnesium salts (struvite, Mg(OH)2, MgSO4, MgO), calcium salts (CaSO4, CaCO3) and other minerals (U, Rb, Cs). Based on the cost and revenues of each technique, an economic comparison has been conducted along with the cost analysis of operating desalination plants.

Production of reactive magnesia from desalination reject brine and its use as a binder

Abstract: This study investigated the feasibility of producing reactive MgO cement from reject brine obtained from a desalination plant and evaluated its use as a binder in comparison to a commercial MgO. The mechanical performance of the samples cured under carbonation conditions for up to 28 days were further supported by x-ray diffraction (XRD), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) and field emission scanning electron microscopy (FESEM) analyses. Samples involving synthetic MgO revealed higher strengths than those with commercial MgO, in line with the higher reactivity of the former. The increased dissolution of synthetic MgO led to its enhanced hydration and carbonation, resulting in samples with denser structures and improved performances. The findings highlighted issues regarding the large-scale production of MgO from reject brine and CO2 emissions of this process. The major environmental impact was associated with the production of the alkali base (NaOH), which could be improved via the identification of sustainable alkali sources used during production. Overall, the production of MgO from reject brine can save natural resources and pave the way for the sequestration of CO2 as stable carbonates in cement-based mixes.

Aligned Millineedle Arrays for Solar Power Seawater Desalination with Site-Specific Salt Formation.

Abstract: As a sustainable and clean water production technology, solar thermal water evaporation has been extensively studied in the past few years. One challenge is that upon operation, salt would form on surface of the solar absorbers leading to inefficient water supply and light absorption and thus much reduced water vaporization rate. To address this problem, a simple solar evaporator based on an array of aligned millineedles for efficient solar water evaporation and controlled site-specific salt formation is demonstrated. The maximum solar evaporation rate achieved is 2.94 kg m-2 h-1 under one Sun irradiation in brine of high salinity (25 wt% NaCl), achieving energy conversion efficiency of 94.5% simultaneously. More importantly, the spontaneously site-specific salt formation on the tips of millineedles endows this solar evaporator with salt harvesting capacity. Rationally separating the clean water and salt from brine by condensation and gravity assistance, this tip-preferential crystallization solar evaporator is not affected by the salt clogging compared with conventional 2D solar evaporators. This study provides new insights on the design of solar evaporators and advances their applications in sustainable seawater desalination and wastewater management.

Anisotropic Evaporator with a T-Shape Design for High-Performance Solar-Driven Zero-Liquid Discharge.

Abstract: Solar-driven evaporation is regarded as a sustainable wastewater treatment strategy for clean water recovery and salt condensation. However, achieving both high evaporation rate and long-term stability remain challenging due to poor thermal management and rapid salt accumulation and blocking. Here, a T-shape solar-driven evaporator, composed of a surface-carbonized longitudinal wood membrane (C-L-wood) is demonstrated as the top "" for solar harvesting/vapor generation/salt collection and another piece of natural L-wood as the support "" for brine transporting and thermally insulating. The horizontally aligned micro-channels of C-L-wood have a low perpendicular thermal conductivity and can effectively localize the thermal energy for rapid evaporation. Meanwhile, the brine is guided to transport from the support L-wood ("") to the centerline of the top evaporator and then toward the double edge (""), during which clean water is evaporated and salt is crystallized at the edge. The T-shape evaporator demonstrates a high evaporation rate of 2.43 kg m-2 h-1 under 1 sun irradiation, and is stable for 7 days of the outdoor operation, which simultaneously realizes clean water evaporation and salt collection (including Cu2+ , CrO42- , Co2+ ), and achieves zero-liquid discharge. Therefore, the T-shape design provides an effective strategy for high performance wastewater treatment.

Effects of nanoparticle shape and size on the thermohydraulic performance of plate evaporator using hybrid nanofluids

Abstract: Brines (ethylene glycol, calcium chloride, propylene glycol and potassium acetate)-based hybrid (combinations of alumina, copper oxide, silica and titania with copper nanoparticles) nanofluids have been used as a secondary refrigerant to improve the heat transfer characteristics of the plate evaporator for milk chilling. Effect of nanoparticle combination, shape and size on heat transfer area, pump work, the ratio of heat transfer coefficient to pressure drop, coefficient of performance, performance index, thermal performance factor and exergetic efficiency has been examined theoretically. Copper oxide–copper hybrid nanofluid gives superior performance, while silica–copper hybrid nanofluid performs well in terms of exergetic efficiency. The maximum decrease in effective heat transfer area (5.9%) is found for propylene glycol brine-based copper oxide hybrid nanofluid. Percentage change in heat transfer area and performance index reduces with an increase in the particle size and is maximum for alumina–copper hybrid nanofluid. However, thermal performance factor increases with particle size. Brick-shaped particles show maximum changes in heat transfer area and performance index, while platelet-shaped particles show worse performance. The study reveals that the nanoparticle shape has a strong influence on the plate heat exchanger performance due to a significant deviation in surface area-to-volume ratio.

Influences of water and salt contents on the thermal conductivity of loess

Abstract: In recent years, with the development of geothermal resources, the thermal conductivity of soil has become a research hotspot. In this study, the thermal conductivity measured by the transient plane heat source method was used to evaluate five common thermal conductivity models from the previous literature. The influences of water content and salt content on the internal heat transfer mode of this soil are explored. It was found that the presence of water in soil changes the conventional mode of point-to-point heat transfer between solid soil particles. With increases in water content, “liquid bridges” are formed between particles. During their formation, NaCl brine can transfer heat in a similar way to water. In this experiment, the model of Usowicz et al. (Intern J Heat Mass Transfer 57:536–571, 2006) was found to best describe the thermal conductivity of soil with salt contents of 0%, 2%, 4% and 6%. This study provides a valuable reference for the development of geothermal resources in the Guanzhong area and for engineering projects in loess areas.

A salt-rejecting solar evaporator for continuous steam generation

Abstract: Recently, great efforts have been focused on solar evaporators because they can localize solar heat on the air-water interface resulting in enhanced photothermal conversion efficiency. However, to prevent salt accumulation during evaporation while maintaining high evaporation rates is still a challenge. In this work, a salt-rejecting solar evaporator was fabricated for continuous seawater desalination. The evaporator was composed of a top layer of carbon black (CB) nanoparticles for solar absorbance, an interlayer of superhydrophilic melamine formaldehyde (MF) foam for both seawater and concentrated brine delivery, and an outlayer of expandable polyethylene (EPE) foam for floating and heat insulation. The superhydrophilic MF foam could offer a channel for rapid exchange of the concentrated brine with the solution beneath, thereby preventing salt accumulation in the evaporator. It was demonstrated that the salt-rejecting solar evaporator produced a high water evaporation rate of 1.24 kg·m−2·h−1 under 1 kW·m−2 solar irradiance, which was 3.2 times higher than that of the pristine simulated seawater (3.5 wt% NaCl solution). Furthermore, the salt-rejecting evaporator displayed an excellent stability as the water evaporation rate remained constant even after 16-cycles of use within 20 days.