Improvement in Process Economy by Using Ro Retentate from Seawater Desalination Into Sodium Carbonate Production (original) (raw)
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Saline waste disposal reuse for desalination plants for the chlor-alkali industry
Desalination, 2011
Seawater desalination has become an important and ever-increasing industry which faces up the environmental situation of water scarcity present in some Mediterranean countries and in the Canary Islands (Spain). This activity presents several environmental drawbacks and negative impacts on marine ecosystems, originated mainly by the discharge into the sea of the generated brine. This emphasizes the need of introducing, in the short-term, new management proposals for this particular case which should be both economically viable and effective, not only for new setting up plants, but also for those already installed. As an alternative to brine disposal, an adequate system has been proposed and developed for the reuse of this saline waste coming from reverse osmosis desalination plants in the chlor-alkali industry by NaCl electrolysis in membrane cells. In this paper, the various treatment phases, necessary for the adaptation of this residue as an alternative raw material resource in the chlor-alkali manufacturing industry, are described. This study has been adapted to Pozo Izquierdo Reverse Osmosis Desalination Plant, in Gran Canaria. This new and different residue reuse as raw material supposes the production and exploitation of new chemical resources, as for example: chlorine, hydrogen gas, and caustic soda.
Computers & Chemical Engineering, 2020
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Waste water recycling by ion-exchange: I. Complete desalination
Desalination, 1980
Recycling of waste water by ion-exchange was studied on a bench scale. Secondary municipal effluent, which had undergone lime flocculation, served as a feed for the ion-exchange system. It was found that both the salt concentration and the organic matter content of the effluent could be reduced to produce high quality water, suitable for a wide range of agricultural and industrial applications. Salt concentrations was reduced from 15 meq/l (750 ppm as CaCO, ) to about 1 meq/l (50 ppm as CaCOs ) and the organic matter, from 70-100 mg/l COD (chemical oxygen demand) to 20 mg/l. The anion exchanger was regenerated with Ca(OH), according to a new method recently developed. The treatment cost for a 2000 m3/day plant was calculated to be 18.0 t/m3. 124 Y. EGOZY, E. KORNGOLD AND N.C. DALTROPHE resources are being utilized. Consequently, the salinity level of ground water is rising steadily. The use of recycled waste water is expected to increase sharply [l] . In the course of the intensive use of fresh water sources and its recycling, there is a salinity buildup in the water sonrces. It is, therefore, necessary to control and reduce this process by incorporating a salinity removal stage in the system. The combination of waste water treatment and salinity removal in a one-process system would be most economical.
Techno-Economic feasibility of extracting minerals from desalination brines
Desalination, 1988
Extraction of minerals from desalination brines represents a potentially important source of minerals. It is usually recommended for reducing fresh water production cost and minimizing waste disposal. In this paper, a techno-economic appraisal for the production of sodium chloride and caustic soda from Saudi desalination brines is presented.
Feasibility of salt production from inland RO desalination plant reject brine: A case study
Desalination, 2003
Production and disposal of reject brine are an integral part of an overall desalination process. For inland desalination plants, this poses a serious challenge to operators, as the option of ocean disposal of reject brine is not available. Various disposal options such as reinjection, lined and unlined evaporation ponds and natural depressions (lake) are currently being used. An alternative approach is to further process the reject brine to extract all the salts. This has the advantages of being environmentally friendly and producing commercial products (i.e., salts and fresh water). A desktop pre-feasibility study using data from Petroleum Development Oman (PDO), operating plants in Bahja, Rima, Nimr and Marmul, confirmed the technical feasibility of treating reject brines in simple processing routes using SAL-PROC technology. SAL-PROC is an integrated process for sequential extraction of dissolved elements from inorganic saline waters in the form of valuable chemical products in crystalline, slurry and liquid forms. The process involves multiple evaporation and/or cooling, supplemented by mineral and chemical processing. An analysis indicated that various types of salts including gypsum, sodium chloride, magnesium hydroxide, calcium chloride, calcium carbonate, and sodium sulphate can be produced from the reject brine of PDO desalination plants. These products have an approximate market value of US $895,000 annually.
New Method for desalination of seawater
The present study explores the possibility of appealing to the laws of inorganic chemistry, i.e., the rules of precipitation to desalinate seawater. Historically, the industry has been using these techniques for the preparation of some compounds. Based on these rules, using suitable salts will react with each other. The results are evident all unwanted salts including sodium chloride are removed. In fact, it is a selective precipitation as other salts which are not harmful are kept such as potassium. The other aim of the study is to reduce the current ratio desalination/power which is very high 60,000 to 80,000 cal/L for distillation (A. Payant. P. Chiliotti L. Sainte-Marie Physic Arm and Colin, Paris, France) or 4.5 kWh/m3 for RO (desalination and water reuse, California, USA) a cause of greenhouse gas except desalination using solar energy. Another aspect of this study, authors noticed rather than consume energy, regeneration or recycling of products provides energy. And in addition, the operation does not cause any pollution
Sodium hydroxide production from seawater desalination brine: process design and energy efficiency
Environmental science & technology, 2018
The ability to increase pH is a crucial need for desalination pretreatment (especially in reverse osmosis) and for other industries, but processes used to raise pH often incur significant emissions and non-renewable resource use. Alternatively, waste brine from desalination can be used to create sodium hydroxide, via appropriate concentration and purification pretreatment steps, for input into the chlor-alkali process. In this work, an efficient process train (with variations) is developed and modeled for sodium hydroxide production from seawater desalination brine using membrane chlor-alkali electrolysis. The integrated system includes nanofiltration, concentration via evaporation or mechanical vapor compression, chemical softening, further ion-exchange softening, dechlorination, and membrane electrolysis. System productivity, component performance, and energy consumption of the NaOH production process are highlighted, and their dependencies on electrolyzer outlet conditions and br...
Fuel Processing Technology, 2018
This paper has addressed the techno-economic feasibility regarding the selective removal of sodium (Na) and calcium (Ca) from low-rank sub-bituminous coal, aiming to reduce the ash slagging and fouling propensity in the pulverized coal-fired boilers. Four novel process integrations were proposed and simulated in Aspen Plus. Both the novel counter-current three-stage water washing process and an acid-water two-stage washing process have proven to improve the ash fusion temperature satisfactorily, reducing the mass fraction of Na 2 O in ash from 4.32 wt% to 0.85 and 0.19 wt%, respectively. In addition, the use of acid-water washing removed 12.5% CaO and 19.5 wt% total ash. For the recycle and treatment of wastewater, the water gain is desirable for the use of an evaporator, owing to the dewatering of the initially high-moisture coal (25 wt%) in the centrifugal and the high water recovery rate from the evaporator. However, the good performance of evaporator was counteracted by the considerable capital cost caused by the huge heat transfer area requirement. Instead, the use of reverse osmosis (RO) resulted in a water loss up to 228.4 kg/t coal. Additionally, prior to the RO treatment unit, the recycle and reuse of the unsaturated water for maximum six times and four times for three-stage water washing and acidwater two-stage washing, respectively, was critical in reducing both the water and power consumption. The water consumption dropped to 38.1 kg/t coal and 48.1 kg/t coal for the three-stage water washing and acidwater two-stage washing process, respectively. Both are remarkably lower than 85.0 kg-water/t black coal. In terms of the power consumption, it decreased to~9.4 kWh/t coal for the three-stage water washing process and further down to 5.8 kWh/t for the acid-water washing case, which was even slightly lower than 6.3 kWh/t for the black coal. Furthermore, the integration of acid-water washing and RO was also demonstrated to be economically viable by its high NPV, IRR and short payback period. Sensitivity analysis indicate that, the original Na content in raw coal is the most influential variable on the water and power consumption of the overall process, followed by the initial moisture content in the raw coal. For a low-rank coal containing > 2150-2520 ppm Na and/or < 19 wt% moisture, the washing process proposed would turn economically unviable compared to the existing black coal washing process. A minimum selling price of 136 RMB/t (−32% deviation) was also necessary to keep both NPV and IRR positive as well as the payback period shorter than the project lifetime.
Desalination, 2020
Desalination of water containing high concentrations of calcium, dissolved carbon dioxide, sulfate, silica and other sparingly soluble salts is difficult because of the scaling potential. An innovative pre-treatment scheme was investigated at bench scale that selectively removes these constituents and produces a soft water to enable desalination with high feed water recovery. The process first removes dissolved carbon dioxide by air stripping at low pH. Magnesium is removed by precipitation at high pH. Calcium is removed by ion exchange (IX), and sulfate is removed by nanofiltration (NF). Cation regenerant from IX, containing calcium, and concentrate from NF, containing sulfate, is combined to precipitate gypsum. Concentrate from the desalination process consisting of a concentrated NaCl solution is used to regenerate the IX resins. The selective precipitation, IX, and NF processes were tested in laboratory experiments and produced magnesium hydroxide and gypsum at greater than 90% and 95% purity respectively. A process model was developed to calculate process performance, mass and liquid flow rates. The MRED process offers the following benefits: 1) greater recovery of brackish feedwater by a desalination process, 2) recovery of marketable commodities and 3) reduction in the volume and mass of waste products from the treatment process.
Journal of CO2 Utilization, 2019
This study presents a novel process integration scheme between CO 2 mineralization and brackish water reverse osmosis (BWRO). The integration is based on the reciprocal nature of these two processes: While CO 2 mineralization needs metal ions such as Na + to convert CO 2 into mineral carbonates like sodium bicarbonate, BWRO is designed to reject such ions to produce fresh water. Thus, there is a potential synergy that can be gained through their integration. To examine the feasibility of such process integration, techno-economic analysis (TEA) and CO 2 life cycle assessment (LCA) are conducted for various possible configurations of the integrated process. A key requirement for TEA and CO 2 LCA is the availability of mass and energy balance data. Therefore, the process is simulated with the commercial simulation software tool of Aspen Plus combined MATLAB. Another requirement is the selection of appropriate evaluation scenarios. Based on a market analysis, the proposed process is assumed to be installed either in the US or in the China to replace a respective conventional benchmark process. Also, two sources of electricity (coal and wind onshore) are considered in the evaluation in order to investigate the sensitivity of the process performance on the type of electricity used. As a result of the analysis, the CO 2 avoidance cost of the designed process is calculated to be 132˜245$/metric ton of CO 2 with wind-based electricity. Given other advantages of the mineralization over the geological storage, the presented process integration between CO 2 mineralization and BWRO deserves further investigation as a means to produce useful chemicals and fresh water while curbing CO 2 emission. Mg 2 SiO 4 (s) + 2CO 2 (g) → 2MgCO 3 (s) + SiO 2 (s) (2) By contrast, the latter option, reacting CO 2 with an alkaline solution (e.g., Eq. (3)) has been applied on a commercial scale in the US. In the Calera carbonate mineralization process, CO 2 from a power plant is converted to CaCO 3 and MgCO 3 using fly ash, brines, and waste water. The pilot plant, which can generate 5 M T (MT: metric ton) of supplementary cementitious material (SCM)/yr, was built in Moss Landing, California. Relative net CO 2 reduction of the Calera concrete compared to the standard concrete is estimated as 1683 lb CO 2 /yd 3 of concrete [7]. In the SkyMine® carbon mineralization pilot project, which was financially supported by US Department of energy, CO 2 from a cement kiln is mineralized to sodium bicarbonate (NaHCO 3) by reaction with a