Desalination Brine Research Articles

Valorisation of Ca and Mg by‐products from mining and seawater desalination brines for water treatment applications

AbstractBACKGROUNDBrines from the drainage of potash mine tailings and from seawater reverse osmosis (SWRO) desalination were previously evaluated as sources of NaCl for the chlor‐alkali industry. Valorisation of NaCl as raw material is required to meet the membrane electrolysis specifications of NaCl saturation and control of interferences (Ca, Mg and sulphate). Brines concentration in NaCl was previously achieved for SWRO brines using electrodialysis (ED). In this work, valorisation of Ca and Mg by‐products via selective recovery was evaluated.RESULTSRecovery of Ca(II) and Mg(II) using chemical precipitation with Na2CO3 and NaOH was evaluated at 25°C and 65°C using one single reagent and mixtures of reagents. The excess of reactants needed to achieve the maximum removal efficiency ranged from 0.35 to 14 g L−1 Na2CO3 and 0.85 g L−1 NaOH. Selective concentration of SWRO brines by ED benefited the purification, as it slightly diluted the antiscalants. The increase of temperatures also benefited their removal process.CONCLUSIONSTotal chemical analysis of Ca and Mg by‐products showed the presence of mixed salts of Ca and Mg when Na2CO3 was used and more pure precipitates of Mg when NaOH was used. In both cases, small amounts of minor traces initially present in the brines were found. © 2014 Society of Chemical Industry.

Microalgae production for nutrient removal in desalination brines

AbstractThis paper will show the results of a research project about nutrient removal from brines by means of microalgae. This work was a part of a much more ambitious project that searches for possible solutions for management of brines. The objectives of the present research about microalgae were: selection of species for nitrate removal in desalination brines; optimization of control parameters; and determination of possible commercial use. None of the most common species of algae used for industrial culture could be adapted to brine conditions. Spontaneous colonisation of brine by species occurring in the surroundings of the desalination plant provided strains that were finally used in the experiments here presented. In laboratory conditions, the best results were obtained for Tetraselmis seucica illuminated with fluorescent tubes with light period 16–18 h and constant temperature of 22°C. In the outdoor pilot plant Oocystis sp was found the most efficient in nitrate removal (45%) and the most product...

Mining Nutrients (N, K, P) from Urban Source-Separated Urine by Forward Osmosis Dewatering

Separating urine from domestic wastewater promotes a more sustainable municipal wastewater treatment system. This study investigated the feasibility of applying a forward osmosis (FO) dewatering process for nutrient recovery from source-separated urine under different conditions, using seawater or desalination brine as a low-cost draw solution. The filtration process with the active layer facing feed solution exhibited relatively high water fluxes up to 20 L/m(2)-h. The process also revealed relatively low rejection to neutral organic nitrogen (urea-N) in fresh urine but improved rejection of ammonium (50-80%) in hydrolyzed urine and high rejection (>90%) of phosphate, potassium in most cases. Compared to simulation based on the solution-diffusion mechanism, higher water flux and solute flux were obtained using fresh or hydrolyzed urine as the feed, which was attributed to the intensive forward nutrient permeation (i.e., of urea, ammonium, and potassium). Membrane fouling could be avoided by prior removal of the spontaneously precipitated crystals in urine. Compared to other urine treatment options, the current process was cost-effective and environmentally friendly for nutrient recovery from urban wastewater at source, yet a comprehensive life-cycle impact assessment might be needed to evaluate and optimize the overall system performance at pilot and full scale operation.

On the thermo-economic optimisation of multistage flash evaporation desalination plants

A thermo–economic optimisation analysis is presented yielding simple algebraic formulae for estimating the optimum number of desalination stages, condensing unit and brine heater size with operating temperatures for distilled water production. The P1–P2 method is used in the present study, together with the thermo–economic analyses of desalination equipments.

Potential for the Simultaneous Capture and Utilization of CO2 Using Desalination Reject Brine: Amine Solvent Selection and Evaluation

In the present study, the potential for the use of different amines with desalination brines for the simultaneous capture and conversion of CO2 into solid bicarbonates was evaluated. The focus of this work was to find the most suitable amine solvent for this proposed process. Various classes of amine solvents such as primary, secondary, tertiary and cyclic amines were identified and evaluated using the following parameters: Precipitate yield, CO2 capacity and Sodium conversion. The results showed that bicarbonate salts of good purity can be synthesized by bubbling simulated flue gas into amine/brine solution. Also the sterically hindered amine, AMP, was found to be the best amine for the process due to its high precipitate yield and sodium conversion. Sodium removal above 80% was obtained when AMP was used. For all amines tested, the precipitated bicarbonate had a purity of over 95% while the CO2 capacity varied, with Piperazine having the highest. The obtained results demonstrate that the proposed process is a promising technology for the simultaneous capture and utilization of CO2 using desalination reject brine.

Desalination Brine Disposal by Submerged Pipes in the Red Sea

Badescu, V.; Ciocanea, A.; Cathcart, R.B., and Finkl, C.W., 2013. Desalination brine disposal by submerged pipes in Red Sea. Journal of Coastal Research, 29(6A), 81–92. Coconut Creek (Florida), ISSN 0749-0208. Seawater desalination plants, especially those in Saudi Arabia, require the disposal of useless posttreatment brine— generally about 50% of the volume of seawater processed by such plants designed to make freshwater. This article focuses on the sustainability of the brine disposal process. A proper decision about the brine disposal method must take into account technical, environmental, and economic constraints. Brine disposal by submerged pipes is considered here; the case of desalination plants in Saudi Arabia on the Red Sea shore is considered as an example. The central concept is the available head at the discharge point. Higher values of the available head ensure larger jet dispersion lengths and better conditions for submarine brine dilution. We assessed the quality of the dilution process by calculating the Froude number of the brine discharge jet, whose optimum values are between 20 to 25. Using the Froude number allows us to find the optimum pipe length and the optimum depth of the discharge point for a sustainable brine disposal. Comments concerning the cost of the submerged pipes are presented.

Characterization of induced struvite formation from source-separated urine using seawater and brine as magnesium sources

Struvite (MgNH4PO4·6H2O) precipitation is widely used for nutrient recovery from source-separated urine in view of limited natural resources. Spontaneous struvite formation depletes the magnesium in hydrolyzed urine so that additional magnesium source is required to produce induced struvite for P-recovery. The present study investigated the morphology and purity of induced struvite crystals obtained from hydrolyzed urine by using seawater and desalination brine as low cost magnesium sources. The results demonstrated that both seawater and brine were effective magnesium sources to recover phosphorus from hydrolyzed urine. Crystals obtained from synthetic and real urine were revealed that the morphology was feather and coffin shape, respectively. Structural characterization of the precipitates confirmed that crystallized struvite was the main product. However, co-precipitates magnesium calcite and calcite were observed when seawater was added into synthetic and real urine, respectively. It was found that the presence of calcium in the magnesium sources could compromise struvite purity. Higher struvite purity could be obtained with higher Mg/Ca ratio in the magnesium source. Comparative analysis indicated that seawater and brine had similar effect on the crystallized struvite purity.

An Experimental Study on Desalination Brine for Electrolytic Chlorination

A power plant in Hebei province aimed to use sodium hypochlorite as fungicide for the circulating water in its seawater electrolysis system by recycling desalination brine. The feasibility of this process was intensively studied using water quality analysis, electrochemical corrosion tests, and dynamic simulation tests. The results showed that this process is more efficient than that using seawater and would not aggravate the corrosion problem that is present in the current system. Scale produced by the electrolysis can be completely removed by acid-washing.

Process optimization of freeze desalination of brine using HybridICETM pilot plant

Freeze desalination of synthetic brines prepared from sodium chloride was investigated. Brine solutions of levels between 2.3% to 10% sodium chloride were used as feed to the plant operated in a batch and continuous mode. The effects of pump, gear motor speed, and differential temperatures on ice formation and purity were investigated. The HybridICE process produced ice of quality levels between 80–96% purity. It was observed that the pump speed was directly proportional to the effluent flow rate coming out of the heat exchangers. Generally, it was observed that the quality of product ice was higher at low to medium flow rates of feed. The gear motor speed variation was inversely proportional to effluent flow rate from the heat exchangers. The HybridICE was found to be a viable desalination technology in terms of quality of water produced, energy consumption, and its easiness to be incorporated into existing refrigeration systems.

Salt recovery from brine generated by large-scale seawater desalination plants

Water shortages in the Middle East and North Africa (MENA) region countries mandate the installation of large-scale desalination plants. Concentrate management requires properly operated cost-effective technologies to reduce the environmental impacts arising from brine discharge. Significant improvement in economics may be obtained by the recovery of chemicals from brines. This study addresses the management of modular brine streams generated from large-scale reverse osmosis desalination plants with microfiltration and nanofiltration (NF) as pretreatment stages. Appropriate salt recovery schemes have been identified and analyzed from the performance and environmental points of view. The economics of salt recovery schemes from NF and reverse osmosis (RO) brine based on evaporation ponds, brine evaporator and membrane crystallizer (MCr) are analyzed and compared. Phased application of the salt recovery program is considered. The results indicate that using NF as pretreatment and adopting salt recovery schemes provide higher water recovery in addition to producing valuable products. The adoption of MCr has high prospects for application in salt recovery from desalination brine. Increasing the capacities of salt recovery systems offers both technical and economic merits.

Use of the desalination brines in the saturation of membrane electrolysis feed

Seawater desalination by reverse osmosis (RO) invokes the necessity of brine disposal. On the other hand, the chlor-alkali industry requires saturated brine with a low content of calcium and magnesium contaminations. This paper describes a preliminary study exploring the possibility of the application of RO, nanofiltration–reverse osmosis, and nanofiltration–reverse osmosis–multieffect distillation seawater desalination brines as a sodium chloride source for membrane electrolysis. A concept has been proposed in which electrodialysis with univalent permselective membranes is used to enrich chlor-alkali lean brine with sodium chloride, and simultaneously desalinate discharge brine. The experiments with an electrodialyzer equipped with Neosepta® ACS and CMS membranes of 42 cm effective length have shown that the desired concentration of membrane electrolysis feed (above 300 g/L as NaCl) can be achieved. At the same time, the concentrations of both calcium and magnesium are decreased, the latter to a greater extent, that facilitates the successive brine purification step.

Analysis of brine desalination with different channels by vacuum membrane distillation

The fluid flow in a rectangular channel is observed by a high-speed fluid field display system, and the fluid appearances under different operate parameters are presented pictorially. Numerical simulations are performed to investigate brine desalination by vacuum membrane distillation (VMD) with three different channel configurations (rectangular, serpentine and spiral) to compare the effect of channel configuration on the process. The results obtained from simulation are analysed from the viewpoint of field synergy. This study concludes that better field synergy leads to better membrane permeability flux. The spiral channel shows the best performance in enhancing heat transfer and increasing the synergy. Increasing the co-direction component of the multi-field could enhance the transfer process. The numerical simulation results are consistent with experimental results.

Evaluation of the performance of a new freeze desalination technology

The use of desalination technologies which produce concentrated brines is acutely limited by inadequate waste brine disposal mechanisms such that the brine does not contaminate fresh water resources. The treatment of highly saline brine using freeze desalination technique trade marked as HybridICE™ technology was investigated at pilot scale. The capacity of the HybridICE™ process to generate fresh water by freeze desalination of brine was investigated in this study. Brine samples to feed into the HybridICE process unit were prepared in tanks with volume capacities between 1.0 and 10.0 m3 by dissolving common salt into tape water. The effects of refrigerant temperature, initial brine concentration, energy consumption were evaluated in relation to product ice quality. Feed brine samples were processed in batches in a closed system where it was continuously re-circulated to generate product ice and more concentrated residual small volume of brine stream. The quality of ice produced could be turned into potable water it terms of its low total dissolved salts and conductivity. The salt removal, based on the average chloride concentration in the ice samples, was 96 %. The energy utilization efficiency amounted to an average of ZAR 10.0/m3 water assuming energy cost of ZAR 0.39/kWh. The HybridICE™ technology was shown to be a better option than other desalination technologies currently in use, in terms of energy utilization and cleaner by-products.

Reuse of SWRO brine for the production of carotenoids from Dunaliella salina and removal of macronutrients

This research determines the advantages of the use of brine from reverse osmosis seawater desalination processes as hypersaline culture media to grow Dunaliella salina. In this work, we evaluated the growth of a new strain of D. salina (Ds. Janubiense-ITC5.105) cultured in residual brine and in artificial hypersaline media compared with the productivity of a well-established strain of this species (Ds. BCA421-ITC5.003). Parameters such as concentration of chlorophylls a and b and total carotenoids accumulated by the two strains throughout the cultivation course were established. The results show maximum biomass yield of 26.44g m-2 d-1 for Ds. BCA421-ITC5.003 grown in a controlled media with similar salinities to that of desalination brine; and maximum carotenoids productions of 20.93 mg m-2 d-1 for Ds. Janubiense-ITC5.105 grown in brine from seawater desalination processes. This SWRO brine would be an ideal medium to grow this kind of species at low cost in areas with seawater desalination plants. Moreover, the growth of D. salina offers a high rate of nutrient fixation, such as NO3- and PO43-, of up to 99 and 71%, respectively. Due to the fact that desalination brine contains certain amounts of these nutrients in its composition, its use as culture media requires a lower reagent expense. The cultivation also favors the complete removal of these ions from brine, thus improving the quality of the final disposal.

How robust is the environmental impact assessment process in South Australia? Behind the scenes of the Adelaide seawater desalination project

Abstract This work tests the robustness of policies and procedures designed to protect South Australia's marine environment through a case study of the Adelaide Desalination Plant—the most expensive (∼A$1.8 billion) infrastructure project in South Australia's history. Although this project has been subject to an Environmental Impact Assessment (EIA)—the highest level of assessment in Australia—on inspection it appears that the current operating licence for the desalination brine discharge breaches Government approval conditions and ignores the collective expert scientific advice of the project's Environmental Impact Statement (EIS). Hence, the EIA process in South Australia for this project is flawed. Improvements could be made to the South Australian system by including the requirements for operating licences as an integral part of the EIA.

An improved life cycle impact assessment (LCIA) approach for assessing aquatic eco-toxic impact of brine disposal from seawater desalination plants

Most Life Cycle Assessment (LCA) studies did not quantify the aquatic eco-toxic potential (aquatic ETP) of the brine disposal mainly due to the limitation of current life cycle impact assessment (LCIA) approaches. The purpose of this study is to develop an improved approach for assessing the aquatic ETP of brine disposal from seawater desalination plants. The proposed approach, named group-by-group approach, calculates the average aquatic ETP as the sum of the impacts generated by acknowledged groups of influential chemicals. This approach firstly identifies the influential chemicals. According to the chemical property and the impact pathway to the aquatic ecosystem, the important chemicals are then categorized into groups under three categories. Depending on the characteristics of the defined groups, different strategies are applied to determine the impact of each group. The group-by-group approach takes the merits of two most commonly-used approaches, chemical specific approach and whole effluent approach. The results from the case study indicated that this approach reduces the reliance on the comprehensive chemical composition analysis and temporal ecotoxicology test of the complex desalination brine. It also provides a more comprehensive coverage, not only considering the impact of organic chemicals and metals, but also including the contribution of inorganic chemicals.

Echinoderms as indicators of brine discharge impacts

Echinoderms are osmoconformer organisms and are expected to be very sensitive to brine discharges. The objective of this study is to examine the use of echinoderms as early warning indicators of the impact of brine discharges and its application in the management of desalination discharges. We sampled using visual census along transect lines, for nine consecutive years and in three different stations, i.e. before the seawater reverse osmosis desalination plant began operating and thereafter. One year after the plant operation, echinoderms disappeared from the localities affected by the desalination brine. When the desalination brine was diluted with seawater prior to discharge, it was observed a recovery of echinoderm densities in these localities. Therefore, echinoderm populations may be used as early indicators to monitor impacts associated with a desalination brine discharge, but also to detect a possible recovery of a previously impacted area when additional mitigation measures to reduce the impact of brine discharge have been implemented.

Desalination by air gap membrane distillation using a two hollow-fiber-set membrane module

Desalination by air gap membrane distillation (AGMD) combines in one device the processes of evaporation of water from hot brine through a porous hydrophobic membrane, condensation of the water vapor so generated on a cold condenser surface and recovery of heat in the condenser cooling liquid which may be the cold/cooled brine. Existing devices for AGMD are bulky due to the condenser arrangements adopted even though evaporation from brine may be carried out with porous hydrophobic hollow fibers. In this research we have developed a two-hollow-fiber-set based compact device where all such functions are combined in a compact device. The first fiber set consists of porous hydrophobic hollow fibers of either polypropylene (PP) or polyvinylidene fluoride (PVDF). The second set of hollow fibers is of solid PP through the bore of each such hollow fiber the cooling liquid is passed and on the outside surface of which water vapor condensation takes place. A number of modules having different packing densities of hollow fibers have been studied for desalination of brine containing 1% NaCl. The performances of such modules have been investigated for a range of feed brine temperatures as well as the flow rates of the two liquid streams, hot brine and the cooling liquid. Enhanced water vapor productivity was achieved in small laboratory devices suggesting potential for scale up.

Comparison of evaporation rates for seawater and brine from reverse osmosis in traditional salt works: empirical correlations

The use of evaporation ponds is one alternative to direct disposal of desalination brine. Evaporation ponds are shallow basins that expose their contents to the environment, reducing liquid volume by means of evaporation. As they resemble traditional salt works that customarily use seawater, evaporation ponds were analyzed for their use for brine desalination management. In order to numerically evaluate this modification, a comparative study of the evaporation rate achieved in both traditional salt works and in evaporation ponds was carried out. Two equations were obtained for each estimation. The numerical expressions are specific for high salinity water as opposed to those available for low salinity water. These equations show the influence of fluid nature, the effect of wind and the lower brine evaporation capacity. It was observed in this study that the difference in brine evaporation capacity through the use of seawater is low enough to indicate that the use of brine in traditional salt works allows an increase in salt production without necessarily multiplying the surface required for evaporation.

Reuse and minimization of desalination brines: a review of alternatives

Abstract Desalination is currently one of the available solutions to the problem of the lack of water present in most countries due to the global increase in water demand. One of the desalination plants main problem is the large amount of reject brine produced, which can very often severely damage the receiving environment. Nowadays, the management of this residue is based mainly in the dilution prior to the discharge. However, there are many emerging alternative technologies that can be combined to achieve a minimization and valorization of brine and thus an appropriate management. This article introduces and describes briefly the set of available techniques. Each alternative has been assessed in terms of technology, economic and environmental merits, resulting in a numeric table.