KR101639848B1 - The manufacturing process of high hardness drinking water using NF/RO/ED membrane connection system - Google Patents

Abstract

The present invention relates to a mineral water quality control technology that removes sulfate ions and chlorine ions during the desalination process of seawater (deep sea water or concentrated water) and retains useful minerals such as magnesium and calcium. More particularly, (ED), nanofiltration (NF) and reverse osmosis (RO) systems using a combination of selective minerals, electrodialysis (ED) and nanofiltration membranes (NF) The removal of materials, and the development of a process linkage system for optimal water quality control during the desalination process. The ERO / NF / ED or NF / ED coupling process is a process that can simultaneously produce deep sea water treatment water containing demineralized water, concentrated water, mineral desalted water, mineral concentrated water and a function, It can save energy, produce deep ocean water treatment in large quantity, remove sulfuric acid ion and chlorine ion, produce mineral concentrated water, adjust the pH of alkaline water produced by adjusting the electric current of electrolytic bath from 10 to 13 Calcium carbonate precipitate is formed at pH 10 and magnesium hydrate is formed at pH 13, so that the calcium and magnesium mineral extract can be separated and extracted, which makes it possible to produce a high hardness water suitable for the quality of the water to be consumed. Energy can be reduced.

Description

The present invention relates to a process for preparing a high-hardness drinking water using NF / RO / ED membrane coupling system,

The present invention relates to a process for manufacturing deep sea water for producing a high hardness water through a seawater desalination process such as deep sea water or concentrated water. More particularly, the present invention relates to a process for producing a deep sea water treated with a nano filtration method (NF) ), And electrodialysis (ED) system, the sulfate and chloride ions contained in the seawater are removed, and magnesium, calcium, etc., which are useful minerals, are concentrated to be remained and the existing desalination methods (evaporation method, reverse osmosis method RO / ED separator coupling system to overcome the problems of high-viscosity water (RO)) and the like.

In general, 1.0 kg of seawater contains 965 g (96.5%) of water, 18.98 g (1.9%) of chlorine ion, 10.556 g of Na ⁺ and 1.1% of sulfate ion and 2.649 g of SO ₄ ^{2 -,} 0.3%), magnesium ion is ^{1.272 g (Mg 2+, 0.1%} ), calcium ion is ^{0.400 g (Ca 2+, 0.04%} ), potassium ions ^{0.38 g (K +, 0.04%} ), bicarbonate ions It is known that 0.14 g (HCO ^{3 -} , 0.01%) of the main component ion is dissolved in 3.4% and the remaining 0.1% is present in the trace metal dissolved and 92 kinds of dissolved substances exist in seawater.

In particular, deep sea water is a sea water that is deep at a depth of 200m or more, which is not reached by the sunlight. It is located far away from the coast and is not mixed with atmospheric or surface water (river) , And deep seawater is structurally blocked from contaminating influent sources such as organic pollutants (such as pathogens and fertilizer pesticides), which are known as marine water resources for a long time. In particular, deep sea water contains various minerals such as zinc, selenium and manganese, as well as the four major minerals (magnesium, calcium, potassium, sodium) have.

It is important to maintain the mineral balance in the body, because deficiency and excess of minerals causes various diseases and hinders physical and mental development. Minerals such as calcium, magnesium, and potassium are important elements that play a role in body composition, body function control, and are one of the five nutrients needed by humans. Among the minerals, calcium (Ca ²⁺ ) functions as bone and tooth formation, muscle, nerve and heart function control, blood coagulation promotion, and in the case of deficiency constipation, osteoporosis, developmental disorder, convulsions, Anxiety and the like occur.

Magnesium (magnesium, Mg ²⁺ ) functions in energy production, regulation of nervous function, stimulation of vitamin B and E metabolism, and in the case of deficiency heart disease, hypertension, renal stone, insomnia, arrhythmia, hypotension, loss of appetite, Anemia, and the like. Potassium (K +) performs functions such as regulation of intracellular acid base balance, moisture regulation, maintenance of neurological function, preservation of cell function, vasodilation, and oxygen supply to the brain. In the case of deficiency, arrhythmia, loss of appetite, Constipation, fatigue, asthenia, and hypoglycemia.

Deep sea water extracts can be a very useful mineral source for modern people whose mineral balance has collapsed due to erroneous eating habits, environmental pollution, and other minerals contained in seawater (deep sea water). However, in the case of sea water, since it contains a considerable amount of salt (NaCl), there is a problem that potassium, calcium, magnesium, etc. which are useful minerals are removed together in the desalination process for removing the salt.

The seawater desalination methods include evaporation method, reverse osmosis membrane method, and electrodialysis method. The evaporation method utilizes the principle of evaporating seawater, evaporating water as a solvent, and leaving a solute. The reverse osmosis membrane method uses an ionic substance dissolved in water as a membrane to exclude salts and pass pure water only The electrodialysis method is a method in which an anion membrane and a cation membrane are alternately arranged and then a DC voltage is applied to an electrode positioned at both ends of an anion membrane and a cation membrane to remove pure water and anions.

In addition, the method of extracting minerals from existing seawater is a method of extracting minerals in seawater by concentrating seawater (deep seawater) by evaporating and separating minerals such as calcium salt and magnesium salt by using difference of solubility.

However, when these desalination methods are used, it is difficult to efficiently separate calcium and magnesium from various minerals contained in seawater, and it is disadvantageous in that the recovery rate of mineral components is low and energy is high. In addition, the mineral salts extracted by the desalination method and the mineral extraction method do not remove the anion ions such as chloride ion (Cl ^- ) and sulfate ion (SO ₄ ^2- ) When the mineral water is re-dissolved to prepare the mineral water, the chlorine ion and the sulfate ion, which are the standard items of water quality to eat, are redissolved, making it impossible to manufacture a high-hardness water having a hardness of 400 or more. In addition, the process of producing high hardness water using evaporation method is energy consuming system which consumes a large amount of energy to evaporate seawater during the process of concentrating seawater.

The present invention relates to an existing desalination method (evaporation method, reverse osmosis (RO), etc.) by adjusting mineral water quality which removes sulfuric acid ion and chlorine ion during the seawater desalination process (deep seawater raw water or concentrated water) and magnesium, (ED), nanofiltration (NF) and reverse osmosis (RO) systems in sea water (deep sea water) desalination process to control selective minerals, By using the ED and NF membranes to remove specific substances and to identify and evaluate the characteristics of the process linkage system for the production of various deep seawater treatment water through the adjustment of the optimum water quality during the seawater desalination process, ED membrane separation system to provide a method for producing mineral extract from deep seawater treated water.

Korean Patent Publication No. 10-732066 discloses a method for producing a water-soluble polymer, which comprises: obtaining concentrated water containing an ion component and fresh water from which the ion component is removed; Separating the crystals of calcium salt, sodium salt and sulfate by heating and concentrating the concentrated water; Concentrating the concentrated water to obtain a mixed salt slurry of a potassium salt and a magnesium salt; Washing the slurry with water to obtain a solution in which the magnesium salt is dissolved and potassium salt crystals; And a step of concentrating the solution in which the magnesium salt is dissolved to obtain a crystal in which a potassium salt and a magnesium salt are mixed and separating the magnesium salt solution having improved purity by filtration to obtain a high purity minerals An efficient extraction method is disclosed. Korean Patent Registration No. 10-0885175 discloses a method for producing a concentrated water and a primary permeated water by passing deep seawater through a pretreatment and then passing it through a RO (reverse osmosis membrane) to prepare a primary concentrated water and a primary permeated water, And the second concentrated water is evaporated and crystallized by using a MVR (Decompression Controlled Vapor Deposition Compression Evaporation) system, the evaporated and crystallized mineral salt is separated into a particle size separator Separating the first permeated water through a second RO (osmotic membrane) to produce a second permeated water and a third concentrated water, and separating the separated mineral salt from the second permeated water And a method for producing mineral salts and mineral salts comprising minerals separated from deep ocean water. In Korean Patent Laid-Open No. 10-2011-0068589, deep-sea water is drawn into the first magnetic treatment reactor for the water to be treated (raw water), and at the same time ozone is injected from the first ozone generator to oxidize and oxidize the oxides After coagulation, the coagulated material is removed from the first filter. Treating the water to be treated in a second magnetic treatment reactor to apply a magnetic force to the ozone generator, injecting ozone into the second ozone generator, passing the ozone through a reaction tank filled with activated carbon, and removing the coagulated material from the second filter ≪ / RTI > is disclosed for an ocean deep seawater desalination system. Korean Patent Laid-Open Publication No. 10-2012-0108402 discloses an MF filtration step; An SWRO step of treating the MF permeated water by reverse osmosis; A BWRO step of treating the SWRO permeate with reverse osmosis; A fresh water intake step of taking BWRO permeated water as fresh water; An NF filtration step of introducing the BWRO concentrated water by the BWRO step into the SWRO step and filtering the concentrated water by the SWRO step with a nanofilter; A low-concentration mineral water intake step of taking NF permeated water with low-concentration mineral water; High-concentration mineral water intake step of taking NF-concentrated water with high-concentration mineral water; Wherein the low-concentration mineral water and the high-concentration mineral water taken in the low-concentration mineral water taking-in step and the high-concentration mineral take-in step are respectively mixed or mixed together to obtain the mineral water from the seawater. . However, such a prior art technique can be used to effectively produce mineral water from deep seawater by using a complex process of nanofiltration (NF), reverse osmosis (RO) and electrodialysis (ED) systems as in the present invention , To remove sulfuric acid ion and chlorine ion, to concentrate the useful minerals such as magnesium and calcium, to reduce the energy cost of production and to meet the drinking water quality standard of high purity, deep sea water treatment using NF / RO / ED membrane connection system The composition for producing a mineral extract from water is not disclosed and shows a difference.

Disclosure of the Invention The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a method for removing minerals such as calcium, magnesium, potassium, etc., It is a way to increase purity while reducing energy. In other words, by using only RO membrane, NF membrane and ED membrane, we developed a process linkage system for optimal water quality control during seawater desalination process, extracting beneficial minerals from clean deep ocean water and massively producing high- This study aims to provide a method of manufacturing high hardness food that meets water quality standards from deep seawater treated by using NF / RO / ED membrane coupling system.

In order to solve the above-mentioned problems, a manufacturing process suitable for producing mineral-concentrated water using the seawater or deep sea water of the present invention and meeting the quality standards of the drinking water is as follows.
1) Deep sea water is pretreated by at least one method selected from among sand filtration, rapid filtration, microfiltration (MF), immersion membrane filter (SMF) and ultrafiltration (UF) filtration to produce reverse osmosis membrane (RO), nanofiltration membrane Supplying an electrodialysis ion-exchange membrane (ED);
2) Preparing the pretreated deep seawater of step 1) supplied to the reverse osmosis membrane (RO) through a reverse osmosis membrane to produce a concentrated deep seawater and a desalted deep seawater;
2-1) supplying the concentrate deep seawater as a nanofiltration membrane (NF), and supplying a desalted deep seawater as a high hardness water dilution water;
3) The deep-seated deep seawater of step 1) and the concentrated water of step 2-1) supplied to the nanofiltration membrane (NF)
3-1) Using the NF membrane, calcium and magnesium ions were concentrated, and 30-60% of the chloride ion and sodium were removed. Mineral concentrated deep seawater was produced. Supplying an electrodialysis ion exchange membrane (ED) and a nanofiltration membrane (NF);
3-2) Through the ultrafiltration membrane (UF) or the anion exchange resin, calcium sulfate and magnesium ion are remained, and sulfuric acid ion (sulfate concentrated water) Supplying water as raw material water;
3-3) The mineral-enriched water supplied back to the NF membrane in 3-1) is circulated by the secondary or tertiary stages of 3-1) and 3-2) to form a mineral concentrated deep seawater. And sulfuric acid (sulfate-removed) water (mineral concentrated desalted (Sulfate removed) water)
4) mixing the desalted deep seawater prepared in the step 2) with the mineral concentrated deep seawater prepared in the step 3-1) and supplying the mixture to the electrodialysis ion exchange membrane ED;
5) activating the electrodialysis ion exchange membrane (ED) and mixing the mixed water supplied in steps 1) and 4);
5-1) The salt concentration tank contains a function of sodium chloride concentration (Deep sea water brine);
5-2) The hardness concentration tank removes the chlorine ion and the sodium ion, while the calcium ion and the magnesium ion are concentrated, and the mineral enriched desalted water having the mineral content ratio ((magnesium + calcium) / sodium) ≪ / RTI >
5-3) The mineral enriched desalted water prepared in step 5-2) is supplied to the nanofiltration membrane (NF) in step 3), and the step 3) and the step 4-2) Circulating through the step;
6) The mineral concentrated water from which sulfate ions have been removed in step 3-2) is diluted with reverse osmosis (RO) desalted water in step 2-1) to obtain a water quality satisfying chloride ion and sulfate ion and a step of preparing a high-hardness water having a concentration of not less than 10 mg / L or less.

Another embodiment of the present invention is as follows.
1) Pre-treatment of seawater (deep sea water) using MF (micro filteration) membrane and then passing it through RO membrane (primary or secondary) to produce concentrated deep seawater and desalted deep seawater,

2) After pretreatment of seawater (deep sea water), calcium and magnesium ions are concentrated by using 2nd or 3rd circulation of NF membrane (3F), while chloride ion and sodium are concentrated 30-60% Mineral enriched deep seawater

3) passing the concentrated mineral water of 2) through a nanofilter (NF) or an ultrafiltration membrane (UF) or an anion exchange resin to produce a mineral concentrated water in which sulfate and magnesium ions are remained,

4) The mineral-concentrated water of the above 3) is activated by the electrodialysis ion exchange membrane (ED) of the electrodialysis equipment to remove chlorine ion and sodium ion by a salt concentration tank, and calcium ion and magnesium ion are concentrated in the hardness concentration tank, Producing a mineral enriched desalted water having a content ratio (magnesium + calcium) / sodium of not less than 1.0,

5) When the concentrated mineral water from which the chlorine ion and the sulfate ion are removed in the above 4) is diluted with the reverse osmosis (RO) demineralized water of the above 1), it is possible to satisfy the water quality standards of chlorine and sulfate, Or more of the high-hardness water,

The pretreatment of the deep seawater in step 1) is carried out through sand filtration, rapid filtration membrane, microfiltration (MF), immersion membrane filter (SMF) and ultra filtration (UF) filtration. In addition to the process of producing concentrated water and desalted water, it is possible to produce ultrapure water having a hardness of less than 1 mg / L by passing the primary RO desalted water through a secondary RO membrane. In addition, the mineral concentrated water produced in the step 2) The membrane is able to produce mineral concentrated water from which sulfuric acid ions have been removed by passing through the membrane, and the deep sea water or reverse osmosis desalted water is used in the salt concentration tank of step 4).

In addition, in step 2), two or one group of the nanofiltration membrane (NF) may be used instead of the group of the nanofiltration membrane (NF) group.

According to the coupling process of the present invention, nanofiltration membranes can be used to concentrate hardness components such as magnesium and calcium, to remove sulfate ions, and to separate sodium ions and chlorine ions from hardness concentrated water using an electrodialysis membrane It is possible to produce high-hardness food which meets the water quality standard of elimination of chlorine ion and sulfate ion component with hardness concentration of 12,600 mg / L, chlorine ion concentration of 2,446 mg / L or less and sulfuric acid ion of 2,500 mg / L or less .

When diluted 10 times with high RO water produced by removing all the dissolved materials by using reverse osmosis membrane, it is suitable to meet the water quality standard of water to be used with 244 mg / L of chloride ion and 250 mg / L of sulfate ion. It is a technology to produce high hardness water with 1,200 mg / L.

With the existing technology, as the hardness concentration increases, the concentration of chlorine ion and sulfate ion increases so that the concentration of chlorine ion and sulfate ion exceeds 250 mg / L, which is the water quality of water, at hardness higher than 400. According to the coupling process of the present invention, it is possible to concentrate hardness components such as magnesium and calcium by using a nanofiltration membrane, to remove sulfate ions, and to separate minerals such as sodium ions and chlorine ions from hardness- When the concentrated water is diluted 10 times with the second RO produced water which has been completely dissolved by the reverse osmosis membrane, the chlorine ion concentration is less than 244 mg / L and the sulfate ion is less than 250 mg / L. mg / L, it is possible to provide hard water for mineral supplement to the people who need mineral supplement.

The present invention relates to a method for producing high-purity water using seawater (deep sea water) by simultaneously using a nanofilter (NF), reverse osmosis membrane (RO) and electrodialysis (ED) It is possible to manufacture high-hardness water suitable for the water quality standard for eating and drinking effective minerals such as potassium and magnesium and low-cost energy of chlorine ion and sulfate ion, and energy consumed in the process can be reduced.

It is possible to efficiently produce mineral raw materials of various products including useful minerals with high purity in manufacturing high hardness water in seawater and to produce deep sea water (desalted water, concentrated water, mineral desalted water, mineral concentrated water, It has the effect of producing calcium and magnesium mineral extracts while producing. It is a process linkage system that can overcome the problems of reverse osmosis (RO), which is widely used in the desalination process of seawater (deep sea water), and it is possible to efficiently produce the deep seawater treated water without introducing additional treatment process.

Figure 1 shows an overall process diagram of a method for producing high-hardness water from seawater (deep sea water) using an NF / RO / ED membrane coupling system. (Reverse osmosis membrane RO is a water- The NF membrane was prepared by using concentrated water of sea water (deep ocean water) or RO salt to remove sulfate ions, and the ED membrane was used to remove sodium ions and chlorine ions, This diluted mineral water is diluted with RO demineralized water to produce a hard water having a hardness of at least 1000 mg / L which is suitable for water quality standards.)
Figure 2 shows a photograph of a NF membrane and RO membrane seawater desalination system.
Figure 3 shows a photograph of an electrodialysis (ED) system.
Figure 4 shows the NF membrane separation performance results.
FIG. 5 shows the results of concentration changes of monovalent ions of sodium and bivalent ions of magnesium in the hardness concentration tank and the salt concentration tank according to the electric conductivity.
6 shows a hardness / chlorine ratio results according to the membrane separation process (RO prod. W (RO production water), RO Conc. W (RO concentration water), 1 st NF Conc. W (1 st NF concentration water), ^{NF 2nd Conc. W (2 nd} NF concentration water), NF 3rd Conc. W (3 rd NF concentration water), ED Hardness (ED Hardness concentration water), NF / ED Hardness W. (NF / ED Hardness water), RO / NF / ED Hardness W (RO / NF / ED process Hardness Pot Water)).

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings, in which: FIG. 1 is a schematic view illustrating a process for producing a mineral extract from a deep sea water treated with an NF / RO / ED membrane according to an embodiment of the present invention; The following is an explanation.

I. Deep sea water treatment process and system composition

1. Nanofiltration membrane - Reverse osmosis membrane - Electrodialysis membrane connection

The present invention relates to an existing desalination method (evaporation method, reverse osmosis (RO), etc.) by adjusting mineral water quality which removes sulfuric acid ion and chlorine ion during the seawater desalination process (deep seawater raw water or concentrated water) and magnesium, FIG. 1 is a flow chart of a method of manufacturing a high-hardness food according to the present invention, which comprises preparing a mineral extract from seawater-treated water using an NF / RO / ED membrane coupling system.

Mineral water is produced by using seawater or deep seawater and the production process of high hardness water suitable for water quality standards is as follows.

1) Pre-treatment of seawater (deep sea water) using MF (micro filteration) membrane and then passing it through RO membrane (primary or secondary) to produce concentrated deep seawater and desalted deep seawater,

2) After pretreatment of seawater (deep sea water), calcium and magnesium ions are concentrated by using 2nd or 3rd circulation of NF membrane (3F), while chloride ion and sodium are concentrated 30-60% Mineral enriched deep seawater

3) passing the concentrated mineral water of 2) through a nanofilter (NF) or an ultrafiltration membrane (UF) or an anion exchange resin to produce a mineral concentrated water in which sulfate and magnesium ions are remained,

4) The mineral-concentrated water of the above 3) is activated by the electrodialysis ion exchange membrane (ED) of the electrodialysis equipment to remove chlorine ion and sodium ion by a salt concentration tank, and calcium ion and magnesium ion are concentrated in the hardness concentration tank, Preparing a mineral enriched desalted water having a content ratio ((magnesium + calcium) / sodium) of 1.0 or more,

5) When the concentrated mineral water from which the chlorine ion and the sulfate ion are removed in the above 4) is diluted with the reverse osmosis (RO) demineralized water of the above 1), it is possible to satisfy the water quality standards of chlorine and sulfate, Or more of the high-hardness water,

The pretreatment of the deep seawater in step 1) is carried out through sand filtration, rapid filtration membrane, microfiltration (MF), immersion membrane filter (SMF) and ultra filtration (UF) filtration. In addition to the process of producing concentrated water and desalted water, it is possible to produce ultrapure water having a hardness of less than 1 mg / L by passing the primary RO desalted water through a secondary RO membrane. In addition, the mineral concentrated water produced in the step 2) The membrane is able to produce mineral concentrated water from which sulfuric acid ions have been removed by passing through the membrane, and the deep sea water or reverse osmosis desalted water is used in the salt concentration tank of step 4).

In addition, in step 2), two or one group of the nanofiltration membrane (NF) may be used instead of the group of the nanofiltration membrane (NF) group.

In the present invention, the process for producing deep-sea water treated in the ocean will be described in more detail as follows.

The entire process is the production of deep sea water (raw water) or RO (reverse osmosis membrane) filtered by pretreatment (sand filtration, rapid filtration membrane, MF filter, SMF membrane filter and UF filter) The water was placed in a salt concentration tank of an electrodialysis apparatus and the concentrated water of NF tertiary mineral through Nano filtration was passed through an ultrafiltration membrane (UF) or an anion exchange resin or an NF membrane, When the removed mineral concentrated water is put into a hardness concentration tank of an ED (electrodialysis membrane) apparatus and then an electric conductivity of 20 to 25 mS / cm is applied to the ED (electrodialysis membrane) apparatus, the chloride concentration and the sodium ion (Magnesium + calcium) / sodium ratio of not less than 1.0 is produced in the hardness concentrating tank, in which concentrated mineral water is produced, and mineral content is higher than seawater.

During the pretreatment process, more than 98% of sulfate ions (SO ₄ ^2- ) are removed from the water produced through the NF, NF or UF. The NF membrane permeates more than 80% of monovalent ions such as sodium potassium and chloride ions. However, magnesium, calcium ions and sulfate ions in raw water do not pass through the NF membrane during the passage through the NF membrane, do.

In the mineral condensed water produced by the NF membrane, 60% of the divalent ions such as magnesium, calcium, and sulfate ions pass through the NF membrane, but they can not pass through the NF membrane and are concentrated in the concentrated water. (NF), calcium, magnesium and sulfate ions can produce concentrated mineral water, compared to the raw water.

The conventional reverse osmosis membrane process, the process is simple, but to the ratio of hardness (mineral) components of the concentrated ((Ca + Mg) / Na) is low chloride ion concentration in water (Cl ^-) and sulfate ions (SO ₄ ^2-) There was a problem in which it could not be separated. The electrodialysis process (ED) can increase the salinity concentration of the concentrated water compared to the reverse osmosis membrane process, but the sulfate ion (SO ₄ ^2- ) is not removed in the hardness concentration tank and the calcium and magnesium ions in the hardness component minerals There was a problem.

In order to solve both problems and increase the production yield, it is possible to combine the nanofilter membrane (NF) - reverse osmosis membrane (RO) - electrodialysis membrane (ED) A concentrated water having a salinity of 7% or more was prepared and a primary mineral-enriched water with a relatively higher concentration of calcium and magnesium than sodium was obtained through a secondary nanofilter membrane (NF), and a tertiary nanofiltration membrane (NF ) Or ultrafiltration membrane (UF) or anion exchange resin to produce sulfate water (SO ₄ ^2- ). Thirdly, sodium and chlorine ions (Cl -) are removed through electrodialysis And concentrated and enriched with calcium and magnesium.

The quality of the water produced depends on how small the amount of sulfate (SO ₄ ^2- ) is, how to remove sodium and chloride ions, and how much potassium, calcium and magnesium are balanced. By combining NF, UF, and ion exchange resin process with ED process in existing RO process, it was possible to produce mineral water with drastically reduced sulfur content. In addition, sodium ion and chlorine ion component are removed through ED process, The factor could be removed and a high concentration of mineral concentrated water could be produced.

2. Composition of NF membrane and RO membrane seawater desalination system

The structure of the NF membrane and RO membrane seawater desalination system used in the present invention is shown in FIG. NF-RO water quality control The seawater desalination system has installed a 3 m ³ / day nano- and reverse osmotic seawater desalination system to produce mineral-enriched water. The NF-RO seawater desalination system consists of two supply pumps, four pretreatment filters, one high-pressure pump, three nano filtration modules, three reverse osmosis membrane modules, and four mineral water conditioning water tanks. In the NF membrane, Ca ²⁺ and Mg ²⁺ ions showed about 30-60% removal, while SO ₄ ^2- ion showed 98% removal, and Na, K, and Cl ions showed 97% transmission. The total dissolved solids (TDS) of the mineral-concentrated water produced by the NF-RO continuous process could be concentrated up to 5 times that of the raw water.

Mineral separation characteristics using electrodialysis membrane (ED) showed that Ca ²⁺ and Mg ²⁺ were concentrated in the hardness concentration tank, and sodium ions and chloride ions were concentrated in the salt concentration tank. Therefore, it is possible to produce high hardness (hardness of about 1,200) that meets water quality standard of sulfate ion and chlorine ion by using high-pressure three-stage NF concentrated water and ED in the NF-RO-ED linked mineral water adjustment desalination desalination process It is also possible to manufacture deep sea water (deionized water, concentrated water, mineral deionized water, mineral concentrated water, water, mineral extract) having various water quality characteristics.

3. Analysis method of water quality of deep sea water

Table 1 shows the method of analyzing the water quality of hard water. Total dissolved matter (TDS), conductivity, salinity and pH were measured with a portable analyzer Seven Multi meter from METTLER TOLEDO. The hardness was measured by the EDTA titration method according to the standard method.

Method of analysis of water quality of deep sea water Items Analytical instruments and mothed TDS, Conductivity, Salinity, pH METTLER TOLEDO Seven Multi meter Hardness EDTA titration Cation:
(Na, Mg, Ca, K) IC (Ion Chromatography)
- model: Cation - ICS-1000, Thermoscientific,
- Cation Column: IonPac CS12A, Anion
(Cl, SO ₄ ^2-) IC (Ion Chromatography)
- model: ICS-1100, Thermoscientific
- Anion Column: IonPac AS14

Cations such as sodium, magnesium, calcium and potassium were analyzed by ion chromatography using a cation column IonPac CS12A from Thermoscientific, and anions such as chloride ion and sulfate ion were analyzed by ion chromatographic analysis using anion column IonPac AS14 from Thermoscientific .

II. System characteristics of reverse osmosis membrane (RO), nanofiltration membrane (NF), electrodialysis membrane (ED) unit process

1. Characteristics of reverse osmosis membrane (RO), nanofiltration membrane (NF), electrodialysis membrane (ED) system

Table 2 shows typical methods of preparing ultrapure water using a reverse osmosis membrane. The primary reverse osmosis (RO) system process uses Toray's reverse osmosis membrane SU810 in three stages and separates the deep seawater from the deep seawater at a pressure of 50 kgf / cm ² into concentrated water and deionized water. The average salt removal rate is 99.75% at the pressure of 50 kgf / cm ² and 3.5% sea water, and the average permeate yield is 4.0 m ³ / d. The second reverse osmosis (RO) system process feeds the production water of the first reverse osmosis membrane to the feed water at a pressure of 20 kgf / cm ² , passes through the third stage of the reverse osmosis membrane SU810 of the Toray Company to produce secondary production water (desalted water) Respectively. The cumulative recovery rate at this time was 60% (Table 2).

In the nano filtration (NF) system process, the membrane of NF membrane SU610 (Toray) was used in three stages. The NF membranes used in this experiment are membranes with specifications of average salt removal rate of 55% and permeate flow rate of 4.5 m ³ / d under feed water conditions of 3.57 kg / cm ² and NaCl 500 mg / l. In this study, deep seawater was treated at a pressure of 20 kgf / cm ² using a three - stage NF membrane to separate primary mineral - enriched water and mineral water (mineral mineral water) NF membrane to obtain secondary mineral-enriched water and mineral demineralized water. The recovery rate of NF 3 membrane was increased when deep sea water was treated twice.

An electrodialysis (ED) system is shown in FIG. The electrodialysis unit (ED) is a batch type unit comprising an electrodialysis unit, a salt concentration unit, a hardness component concentration unit and an electrode solution unit. This device uses Micro Acilyzer O2 from Astrom Corporation of Japan. In the electrodialysis system, deep seawater, concentrated water, or mineral concentrated water was added to the electrodialysis bath and RO production water (desalted water) or deep sea water was added to the saline concentration tank.

ED system process was conducted by using different electrolytic treatment (0.1N NaNO ₃ ) and Conductivity (20 ~ 25 mS / cm). Then, the electrodialysis (ED) raw water was used as the comparative data.

2. Mineral separation characteristics of NF membrane and RO membrane

(NF membrane: Toray SU-610) was used for the production of water and concentrated water using a three-stage module reverse osmosis membrane (RO membrane: Toray SU-810) (Water content of mineral water) and mineral water (water content of minerals concentrated water) and mineral water (mineral acid concentrated water) treated with deep seawater raw water by electrodialysis membrane (Micro Acilyzer O2 of Japan Astrom Inc.) (TDS), hardness, and chlorine concentration) are shown in Tables 2, 3 and 4, respectively.

Water quality of raw water deep seawater used for the test was a total dissolved solid concentrations 34,250 mg / L, hardness of 6,400 mg / L, chlorine ion concentration (Cl ^-) was 18,789 mg / L, hardness / TDS ratio is 0.187, the hardness / Cl- ratio 0.341 and the TDS / Cl ^- ratio was measured as 1.823 (Table 2). The concentration of magnesium ion (1,248 mg / L) and the concentration of calcium ion (402 mg / L) in seawater deep seawater were similar to those of total dissolved solute (TDS) (Lenore S. C et al., 1998) were used to calculate the hardness value in terms of calcium carbonate,

Hardness as calcium carbonate (mg / L) = 2.497 x [Ca] + 4.119 x [Mg]

Calcium carbonate equivalent hardness value calculated by the above equation is 6,143 mg / L, which is similar to the hardness value measured by EDTA titration. The ratio of chlorine ion in the total dissolved matter is 54.8%, and the proportion of chlorine ion in the total dissolved matter is over half. On the other hand, hardness concentration due to calcium and magnesium accounted for only 18.7% of the total dissolved matter, and only 34% of the concentration of chlorine ion was contained. Therefore, the hardness concentration in deep seawater was lower than that of chloride ion or sodium ion.

The TDS concentration was 162 mg / L, the hardness was 20 mg / L and the chlorine ion concentration was 88 mg / L. The hardness / TDS ratio was 0.122, the hardness / Cl ratio was 0.226, and the TDS / Cl ratio was 1.846 (Table 2). 99.5% of total dissolved matter, 99.7% of hardness component and 99.5% of chlorine ion were removed during the process of passing the deep sea water through the reverse osmosis membrane (RO membrane). The hardness / TDS ratio, hardness / Cl ratio and TDS / Cl ratio were similar to the hardness / TDS ratio, hardness / Cl ratio and TDS / Cl ratio in deep seawater. Therefore, the reverse osmosis membrane (RO membrane) can remove 99.5% of seawater dissolved substances, and the hardness component composed of divalent dissolved ions can not be separated from total dissolved matter or chlorine ion. The production water (desalted water) passing through the reverse osmosis membrane also met the water quality standard of deep ocean water to eat.

The TDS concentration of the concentrated water not passing through the reverse osmosis membrane of the third stage module was 45,380 mg / L, the hardness was 8,420 mg / L, and the chloride ion concentration was 28,858 mg / L. The hardness / TDS ratio was 0.186, the hardness / Cl ratio was 0.353, and the TDS / Cl ratio was 1.902. During the process of concentrating the deep sea water, the total dissolved substance was concentrated 32%, 32%, and 54%, respectively, compared to the raw water.

However, the hardness / TDS ratio, hardness / Cl ratio and TDS / Cl ratio were similar to the hardness / TDS ratio, hardness / Cl ratio and TDS / Cl ratio in deep seawater. Therefore, the reverse osmosis membrane (RO membrane) can remove 99.5% of seawater dissolved substances, and the hardness component composed of divalent dissolved ions can not be separated from total dissolved matter or chlorine ion. The water quality of the production water passing through the secondary reverse osmosis membrane showed a water quality close to ultrapure water with total dissolved substance (TDS) concentration of 3 mg / L, hardness of 1 mg / L and chlorine ion concentration of 2 mg / L (Table 2) .

Result and Condition of Deep Sea Water Treatment Process Using Reverse Osmosis Membrane Items seawater RO water (3 modules) -1st RO water (3 modules) -2st Production water-1st (desalination) Concentration water Feed water (production water-1st) Production water-2nd (desalination) (mg / L) (mg / L) (mg / L) (mg / L) (mg / L) TDS 34,250 162 45,380 162 3 Hardness (CaCO3) 6,400 20 8,420 20 <1 Cl- 18,789 88 23,858 88 2 Hardness
/ TDS 0.187 0.122 0.186 0.122 - Hardness
/ Cl- 0.341 0.226 0.353 0.226 - TDS / Cl- 1.823 1.846 1.902 1.846 1.304 Operation condition RO: Toray SU810, pressure: 50 kgf / cm2 RO: Toray SU810, pressure: 20 kgf / cm2 Process seawaterROconcentration water / production water seawaterROconcentration water / production water-1stproduction water-1st (Feedwater) ROproduction water-2nd

However, the hardness / TDS ratio, hardness / Cl ratio and TDS / Cl ratio were similar to the hardness / TDS ratio, hardness / Cl ratio and TDS / Cl ratio in deep seawater. Therefore, the reverse osmosis membrane (RO membrane) can remove 99.5% of seawater dissolved substances, and the hardness component composed of divalent dissolved ions can not be separated from total dissolved matter or chlorine ion. The water quality of the production water passing through the secondary reverse osmosis membrane showed a water quality close to ultrapure water with total dissolved substance (TDS) concentration of 3 mg / L, hardness of 1 mg / L and chlorine ion concentration of 2 mg / L (Table 2) .

The TDS concentration was 26,857 mg / L, the hardness was 1,040 mg / L, and the chlorine ion concentration was 14,623 mg / L in the production water after one pass through the NF membrane of the three-stage module (Table 3).

The hardness / TDS ratio was 0.039, the hardness / Cl ratio was 0.071, and the TDS / Cl ratio was 1.837. During the process of passing through the NF membrane with membrane pore size of 1 nano meter (10 ^-9 m), 78% of total dissolved matter and 77.8% of chlorine ion were passed, but the hardness component including magnesium and calcium passed through the raw water Only 16% passed through the NF membrane.

Results and conditions of deep sea water treatment process using NF system Items seawater NF water-1st NF water-2nd NF water-3rd 생산 물 Concentration water-1st Feed water (concentration water-1st) Concentration water-2nd Feed water (concentration water-2nd) Concentration water-3rd (mg / L) (mg / L) (mg / L) (mg / L) (mg / L) (mg / L) (mg / L) TDS 34,250 26,857 47,742 47,742 55,400 55,400 67,400 Hardness (CaCO3) 6,400 1,040 16,033 16,033 34,100 34,100 47,900 Cl- 18,789 14,623 25,422 25,422 31,551 31,551 38,641 Hardness / TDS 0.187 0.039 0.336 0.336 0.616 0.616 0.711 Hardness / Cl- 0.341 0.071 0.631 0.631 1.081 1.081 1.240 TDS / Cl- 1.823 1.837 1.878 1.878 1.756 1.756 1.744 Operation condition NF: ToraySU610, pressure: 20kgf / cm2 (recovery: 62.7%) NF: Toray SU610, pressure: 20 kgf / cm2 x 2 (recovery: 31.2%) NF: Toray SU610, pressure: 20 kgf / cm2 x 2 (recovery: 18.8%) Process seawaterNFconcentrationwater / productionwater seawaterNFconcentration water-1st / production waterfeedwater (concentration water-1st) NFconcentration water-2nd seawaterNFconcentration water-1st (feed water) NFconcentration water-2nd (feed water) NFconcentration water-3rd

  The hardness / TDS and hardness / Cl ratios were reduced to 80% and 79%, respectively, compared to the hardness / TDS ratio and hardness / Cl ratio in the deep seawater. However, the TDS / Respectively.

Therefore, the nanofilter membrane (NF membrane) can remove only 22% of the sodium or chlorine ions that occupy most of the dissolved water in the seawater raw water, but 84% of the hardness component composed of the divalent dissolved ions such as magnesium and calcium It is possible to separate the total dissolved substance or the chloride ion and the hardness component.

The TDS concentration of 47,742 mg / L, the hardness of 16,033 mg / L, and the chloride ion concentration of 25,422 mg / L were not significantly different from those of the mineral concentrated water that did not pass through the NF membrane of the 3-stage module . The hardness / TDS ratio was 0.336, the hardness / Cl ratio was 0.631, and the TDS / Cl ratio was 1.878. 22% and 22.2% of the total dissolved solids in the deep seawater remained in the concentrated water without passing through the NF membrane. On the other hand, 84% of the raw water containing magnesium and calcium did not pass through the NF membrane, .

Therefore, the concentration of total dissolved substance and chloride ion were 39% and 35% higher than those of deep sea water, respectively, but the hardness concentration was 250% higher than that of raw water. The hardness / TDS ratio and the hardness / Cl ratio of the first concentrated water of the nanofilter were 80% and 85%, respectively, compared with the hardness / TDS ratio and hardness / Cl ratio in the deep seawater. However, Similar to the TDS / Cl ratio in raw water.

The nanofiltration membrane (NF membrane) can concentrate only about 40% of the sodium or chloride ions that make up the bulk of dissolved water in the seawater source water, but the hardness component composed of divalent dissolved ions such as magnesium and calcium can be concentrated at 250% , More than 85% of the univalent ions such as chlorine and sodium can be concentrated. Therefore, it is possible to separate univalent ion components including sodium and chlorine ions and hard components including bivalent ions including calcium and magnesium in seawater.

Concentrated water from the NF membrane of the three-stage module was treated again with the feed water of the three-stage module NF membrane to prepare a second NF concentrated water. The water quality of the secondary NF enriched water was 55,400 mg / L, 34,100 mg / L, and 31,551 mg / L, respectively. The hardness / TDS ratio was 0.616, the hardness / Cl ratio was 1.081, and the TDS / Cl ratio was 1.756. The total dissolved matter concentration (TDS) and chloride ion concentration increased by 62% and 67%, respectively, in the second NF enriched water compared to the first NF enriched water, while the hardness concentration increased by 212% in the second NF enriched water.

The hardness / TDS and hardness / Cl ratios of the secondary NF enriched water increased to 200% and 171%, respectively, compared to the hardness / TDS and hardness / Cl ratios in the primary NF enriched water, while the TDS / It is similar to the TDS / Cl ratio in deep seawater and primary NF enriched water. Therefore, when the seawater is repeatedly concentrated by using the nanofilter membrane (NF membrane), the hardness component concentration can be concentrated by 200% or more for each concentration degree. In addition, the hardness / TDS ratio and the hardness / Cl ratio can be greatly increased in the secondary NF concentrated water as compared with the first concentrated water, so that the hardness component can be finely separated from the total dissolved substance and the chloride ion (FIG. 4).

Secondary NF concentrated water (mineral concentrated water) should be removed because it contains more than 10,000 mg / L of sulfate ion. For this purpose, a nano-filtration (NF) membrane having a pore size of 5 to 10 nm or an ultrafiltration membrane having a pore size of 10 to 30 nm can be used, and a strong basic anion exchange resin or a weakly basic anion exchange resin Can be used.

3. Mineral separation characteristics of electrodialytic membrane (ED)

Electrodialysis membrane (ED) system is composed of electrodialysis unit, salt concentration unit, hardness component concentration unit and electrode solution unit as a batch type device. ED system process was carried out by using 0.1N NaNO ₃ electrolyte and using the condition of 20 mS / cm of conductivity and putting deep sea water into the salt concentrator and the hardness concentrator.

When the ED system was operated for 20 minutes and the conductivity reached 20 mS / cm, the water content of the mineral concentrated water produced in the hardness concentrating tank was 5,810 mg / L for total dissolved substance (TDS), 5,100 mg / L for hardness, The concentration was 3,687 mg / L (Table 4). The hardness / TDS ratio was 0.878, the hardness / Cl ratio was 1.383, and the TDS / Cl ratio was 1.576.

During the process of passing the deep seawater through the electrodialysis membrane, 83% of the total dissolved matter and 73% of the chloride ion were removed, but only 20% of the hardness components including magnesium and calcium were removed from the hardness concentration tank of the ED system. The TDS / Cl ratio of the concentrated water of the hardness concentrator was similar to the TDS / Cl ratio of the deep seawater. However, the hardness / TDS ratio and the hardness / Cl ratio were lower than the hardness / TDS ratio and hardness / 7.7 times and 7.1 times, respectively. Therefore, in the hardness concentration tank of the electrodialysis membrane (ED membrane) sheet, the hardness component composed of divalent dissolved ions such as magnesium and calcium could be concentrated to 700% as compared with the total dissolved substance or chloride ion.

On the other hand, when the conductivity reached 20 mS / cm, the water concentration of the concentrated water produced in the salt concentration tank was 68,000 mg / L, 8,250 mg / L, and 41,565 mg / L, respectively. The hardness / TDS ratio was 0.121, the hardness / Cl ratio was 0.193, and the TDS / Cl ratio was 1.636. In the course of the deep sea water passing through the electrodialysis membrane, the total dissolved substance was doubled and the chloride ion was 2.2 times more concentrated than the raw water. However, the hardness component including magnesium and calcium was only 30% Concentrated in an enrichment tank. The TDS / Cl ratio of the mineral concentrated water of the saline concentrator was similar to the TDS / Cl ratio of the deep seawater of the ocean, but the hardness / TDS ratio and the hardness / Cl ratio were lower than the hardness / TDS ratio and hardness / Respectively, to 65% and 58%, respectively.

Results and Condition of Treatment of Deep Ocean Water Using ED System Items seawater ED water hardness conc. pure conc (mg / L) (mg / L) (mg / L) TDS 34,250 5,810 68,000 Hardness (CaCO3) 6,400 5,100 8,250 Cl- 18,789 3,687 41,565 Hardness / TDS 0.187 0.878 0.121 Hardness / Cl- 0.341 1.383 0.198 TDS / Cl- 1.823 1.576 1.636 Operation condition ED: Electrolyte (0.1N NaNO3), Conductivity (10 mS / cm) Process hardness conc pot (seawater) ED 20 mS / cm salt conc pot (brine water), hardnes conc pot (mineral concentrated water)

Therefore, in the salt concentration tank of the electrodialysis membrane (ED membrane) system, it was possible to concentrate dissolved substances such as total dissolved substances and univalent dissolved ions such as chloride ions.

The hardness / Cl-ratio and the hardness / TDS ratio of the electrodialysis process for separating monovalent and divalent ions present in deep seawater are determined by the type of sample (RO production water, deep ocean water source) and the hardness concentration tank The type of the sample to be injected (tertiary NF concentrated water) and the set value of the electric conductivity.

In the electrodialysis system, the electric conductivity value was set to the set value (Fig. 5). The electric conductivity at which the separation of monovalent ions (sodium and potassium) and bivalent ions (magnesium and calcium) As shown in FIG. 5, when the deep-water raw water is put into a hardness concentration tank and a salt concentration tank and the desalination process is performed using an electrodialysis membrane using an electrolytic solution, a monovalent ion in the hardness concentration tank (treated water) and the salt concentration tank (concentrated water) Changes in the concentration of sodium and divalent ions of magnesium occur. In the saline concentration tank (FIG. 5, concentrated water (green triangle)), the sodium ion concentration as a monovalent ion increases rapidly as the electric conductivity decreases from 35 mS / cm to 20 mS / cm and then to 20 mS / cm or less Respectively. As the electrical conductivity decreased as the desalination of the electrodialysis device progressed, the concentration of sodium in the hardness concentrator (Fig. 5, treated water (red square)) was steadily decreased.

The sodium concentration in the deep sea water (electric conductivity of 40 mS / cm) is about 11,000 mg / L, but the concentration of sodium in the concentrated water of the saline concentration tank (FIG. 5, green triangle) (30,000 mg / L) at the electric conductivity of 20 mS / cm, and the sodium concentration was decreased continuously from 20 mS / cm to 5,000 mg / L at the hardness concentration tank (treated water, red square).

On the other hand, the magnesium ion concentration as the bivalent ion was maintained at a constant level as the electric conductivity decreased from 35 mS / cm to 20 mS / cm as the electrodialysis progressed in the salt concentration tank (FIG. 5, concentrated water (green triangle) mS / cm. As the desalination of the electrodialysis device progressed, the electrical conductivity decreased and the concentration of magnesium in the hardness concentration tank (FIG. 5, treated water (red square)) decreased sharply at 20 mS / cm or less. The concentration of magnesium in the deep sea water (electric conductivity of 40 mS / cm) is about 1,500 mg / L, but the desalination process proceeds and the electric conductivity decreases to 20 mS / cm. The magnesium concentration remained constant and increased to 18,000 mg / L at 20 mS / cm or less. The concentration of magnesium in the hardness concentration tank (Fig. 5, treated water, red squares) maintained a constant concentration until the electric conductivity of 20 mS / cm, and decreased rapidly at the electric conductivity of 20 mS / cm or less, And decreased to 600 mg / L.

As the electrodialysis progresses, monovalent ions (sodium and potassium) in the hardness concentration tank (FIG. 5, treated water, red square) decrease continuously as the electrical conductivity decreases, while the bivalent ions (magnesium, calcium) lt; RTI ID = 0.0 &gt; mS / cm. &lt; / RTI &gt; However, when the electric conductivity is lower than 20 mS / cm, the concentration of divalent ions (magnesium) in the treated water of the hardness concentration tank sharply decreases. Therefore, it has been found economically advantageous to set the electric conductivity to 20 mS / cm to separate monovalent ions and bivalent ions.

III. Structure and Characteristics of Nano Filtration Membrane (NF), Reverse Osmosis Membrane (RO), Electrodialysis Membrane (ED)

1. Construction of NF, RO, ED (Electrodialysis) process system

The hardness / Cl ^- ratio was determined as a factor for determining the degree of separation of monovalent ions and bivalent ions for each type of desalination membrane. The hardness component representing the divalent ion (magnesium, calcium) and the hardness / Cl ^- ratio, which is the ratio of chlorine as a representative element of the elemental element in seawater (deep ocean water) It indicates a lot. The results of the hardness / Cl ^- ratio in the concentrated water according to the type of desalination membrane show that the hardness / Cl ^- ratio increases in the order of raw water <RO <NF first order <NF second order <ED (FIG.

Hardness / Cl in the raw ^water-in ratio is 0.341, RO water and concentrated hardness / Cl ^- ratio but similar to 0.353, a primary NF concentrated water hardness / Cl ^- ratio of 0.631, the second NF concentrated water hardness of / Cl ^- ratio Was 1.240, more than doubled. The hardness / Cl ^- ratio was 1.383 in the concentrated water of the hardness concentrator using the electrodialysis membrane.

In other words, the dissociation of dissolved solids such as magnesium and calcium and the dissolved ions such as chlorine ion and sodium ion is the lowest in the reverse osmosis membrane-concentrated water, and the concentration of NF 1, NF 2, and ED hardness (Fig. 6).

The hardness / TDS ratio was also analyzed as a factor for determining the degree of separation of monovalent ions and bivalent ions for each type of desalination membrane. Hardness / TDS in concentrated water by type of desalination membrane As a result, the hardness / TDS ratio was found to be higher in the order of the raw water <RO <NF first order <NF second order <ED. The hardness / TDS ratio in the raw water is 0.187, the hardness in the RO concentrated water / TDS The ratio was similar to 0.186, but the primary NF enriched water was hardness / TDS Ratio of 0.336, hardness of secondary NF concentrated water / TDS The ratio increased more than 2 times to 0.711.

In addition, in the concentrated water of the hardness concentration tank using the electrodialysis membrane, the hardness / TDS The ratio was 0.878. In other words, dissolution hardness components such as magnesium and calcium are hardly separated in the concentrated water using reverse osmosis membrane, while the hardness component and total hardness component of NF 1 concentration, NF 2 concentration and ED hardness concentration, (Fig. 1). Fig. 2 shows the results of the separation of the dissolved components. Based on these results, it was possible to develop an additional RO-NF-ED coupled manufacturing process for high hardness water with high mineral content.

The process of increasing hardness / Cl ^- ratio by using seawater or deep seawater as raw water is as follows. The process of concentrating magnesium and calcium in NF-enriched water was repeatedly carried out using a nanofiltration membrane that passed univalent ions such as sodium but filtered hardness components such as magnesium and calcium. For the specific process, NF filter SU-610 manufactured by Toray Co., Ltd. was used and the raw water of deep seawater was filtered at a pressure of 20 kgf / cm ² to separate the NF production water and the NF concentrated water from the primary one. And then passed through a NF membrane to produce a second NF enriched water. This process was carried out in three steps to prepare a third NF enriched water. The recovery rate of the third NF enriched water from the raw water was 18.3%. NF concentrated water production process and operating conditions are as follows (Table 5).

Process and operating conditions of concentrated water in NF system item process operation condition conc water quality (mg / L) TDS hardness hardness / Cl NF process seawaterNFconcentrationwater-1st (feedwater) NFconcentrationwater-2nd (feedwater) NFconcentrationwater-3rd NF 20 kgf / cm ² , recovery 18.3%, SU-610 (Toray) 67,400 47,900 1.24

The tertiary NF enriched water such as magnesium and calcium was concentrated by using an electrodialysis membrane to remove univalent ions such as sodium and chlorine while leaving the hardness component. In other words, when the electrodialysis membrane is used, univalent ions such as sodium and chloride ions are continuously removed in the hardness concentration tank (treated water) until the electric conductivity of the raw water decreases from 40 mS / cm to 20 mS / cm. However, (Fig. 5). However, when the electric conductivity is 20 mS / cm or lower, the hardness components such as magnesium ions and calcium ions in the hardness concentration tank are removed as univalent ions such as sodium and chloride ions, so the electric conductivity is set to 20 mS / cm.

The RO / NF / ED process for increasing the hardness / Cl ^- ratio using a specific reverse osmosis membrane (RO), nanofiltration membrane (NF) and electrodialysis membrane (ED membrane) is as follows (Table 6). When the RO water is charged to the saline concentration tank of the electrodialysis unit and the NF concentrated water is charged to the hardness concentration tank and the electrodialysis membrane is operated for 20 minutes and the electric conductivity reaches 20 mS / cm, the salinity concentration tank produces a function, Mineral water was produced in the concentration tank.

The NF / ED process for increasing the hardness / Cl ^- ratio using only the nanofiltration membrane (NF) and the electrodialysis membrane (ED membrane) is performed by adding deep sea water to the salt concentrator, adding a tertiary NF concentrator to the hardness concentrator, When the electrodialysis membrane is operated for 10 minutes at 20 mS / cm, sodium ion and chloride ions are concentrated in the salt concentration tank, and hardness components such as magnesium and calcium are concentrated in the hardness concentration tank to produce mineral concentrated water .

Concentrated water production process and operating conditions of RO / NF / ED, NF / ED coupling process Item Production process Operation condition RO / NF / ED process Salt concatration tank (RO production water), Hardness conc 20 mS / cm ED salinity concentrator, Hardness concentrator (Mineral concentrate) - Electrodialysis equipment: use Micro Acilyzer O2 from Astrom Inc.
- Electrical conductivity: 20 mS / cm
- Driving time: 10 minutes NF / ED process Salinity concentration tank (deep sea water source), hardness concentration tank (third NF concentrated water) 20 mS / cm ED salinity concentration tank, hardness concentration tank (mineral concentrated water) - Electrodialysis equipment: use Micro Acilyzer O2 from Astrom Inc.
- Electrical conductivity: 20 mS / cm
- Driving time: 10 minutes

2. Mineral separation characteristics of the nanofiltration membranes (NF), reverse osmosis membranes (RO), and electrodialysis membranes (ED)

Table 7 shows the water quality data of the hardness concentrator and the saline concentrator after the electrodialysis process through the RO / NF / ED coupling process and the NF / ED coupling process. In the RO / NF / ED coupling process, before the electrodialysis, the hardness concentration tank is filled with the third NF concentrated water, the salinity concentration tank is filled with the RO production water, and the electrodialysis is performed. Concentrated mineral water was produced.

The water quality of the mineral-concentrated water produced in the hardness concentration tank after the electrodialysis was 8,130 mg / L, 12,600 mg / L in total dissolved substance (TDS) and 2,446 mg / L in chlorine ion concentration, Was concentrated more than two times, whereas chlorine ion was 7.7 times smaller than that of raw water. As a result, the hardness / Cl ratio in the hardness concentration tank increased to 15.1 times as much as that of the raw water.

Mineral water produced through the RO / NF / ED coupling process has a hardness of 12,600 mg / L and a chlorine ion concentration of 2,446 mg / L. These mineral-enriched water is used as a secondary RO product using reverse osmosis membrane (TDS 3 L of hardness of less than 1 mg / L, Cl of 2.3 mg / L) and a hardness of less than 250 mg / L of deep sea water quality standard of hardness of 1,260 mg / L and 10 times dilution of chlorine ion Respectively.

In the NF / ED coupling process, NF enriched water was added to the hardness concentrator before electrodialysis, and deep seawater was added to the saline concentrator to conduct electrodialysis. The water quality of the mineral-concentrated water produced in the hardness concentrator was 8,230 mg / L of total dissolved substance (TDS), 12,417 mg / L of hardness, and 3,191 mg / L of chlorine ion concentration, While the chloride ion was 5.8 times lower than that of the raw water. The hardness / Cl ratio in the hardness concentrator was increased to 11.4 times as much as that of the raw water, while the hardness component / concentration ratio was increased to 3.891.

The hardness / Cl-ratio in the raw water was 0.341 and the reverse osmosis (RO) concentration was 0.35, similar to that of the raw water. In the RO membrane, the separation of hard component (bivalent ion) and univalent ion (chlorine, sodium) did not occur. However, in the NF (NF) process, the hardness component was concentrated as the deep seawater was concentrated using NF filtration membrane at 0.631 for primary NF, 0.871 for secondary NF, and 1.250 for tertiary NF. In addition, the hardness component was concentrated and the chlorine ion was removed from the deep seawater using an electrodialytic membrane (ED), whereby the hardness / Cl ratio could be increased to 1.383 (FIG. 6).

Results of NF / RO / ED, NF / ED coupling process and component analysis Items seawater RO / NF / ED process NF / ED process before operation ED after operation ED before operation ED after operation ED (mg / L) hardness conc. pot (mg / L) salt conc. pot (mg / L) hardness conc. pot (mg / L) salt conc. pot (mg / L) hardness conc. pot (mg / L) salt conc. pot (mg / L) hardness conc. pot (mg / L) salt conc. pot (mg / L) TDS 34,250 67,400 304 8,130 57,800 67,400 30,200 8,230 69,200 Hardness (CaCO3) 6,400 47,900 32 12,600 34,000 47,900 6,400 12,417 33,467 Cl- 18,789 38,641 211 2,446 41,228 38,641 17,725 3,191 32,543 Hardness / TDS 0.187 0.711 0.105 1.550 0.588 0.711 0.212 1.509 0.484 Hardness / Cl- 0.341 1.240 0.152 5.151 0.825 1.240 0.361 3.891 1.028 TDS / Cl- 1.823 1.744 1.441 3.324 1.402 1.744 1.704 2.579 2.126 Operation condition ED: Electrolyte (0.5N NaNO3), Conductivity (20 mS / cm) ED: Electrolyte (0.5N NaNO3), Conductivity (20 mS / cm) Process salt conc. pot (RO production water), Hardness conc. pot (NF conc. Water-3rd) ED 20 mS / cm salt conc. pot (brine), Hardness conc. pot (mineral conc. salt conc. pot (seawater), Hardness conc. pot (NF conc. Water-3rd) ED 20 mS / cm salt conc. pot (brine), Hardness conc. pot (mineral conc.

On the other hand, the process of linking RO membrane, nanofiltration membrane, and electrodialysis membrane increases hardness components such as magnesium and calcium and removes monovalent ions such as sodium and chlorine ions to increase hardness / Cl ratio. The hardness / Cl ratios of the hardness concentrates produced in the NF / ED and RO / NF / ED coupling processes were 3.891 and 5.151, respectively, and the hardness / Cl in the deep seawater concentrated water produced using the NF or ED membrane alone Which is 3 to 5 times higher than the ratio.

By using the deep ocean water treatment process using the NF / RO / ED membrane connection system for the optimal water quality adjustment during seawater desalination, energy is saved compared with the technology including the existing evaporation method, and a large amount of deep sea water treatment (Hardness of 1,200 mg / L) which can meet the drinking water quality standard because it is possible to produce concentrated mineral water which is rich in magnesium and calcium which are useful minerals while removing sulfate ion and chlorine ion. And mineral extracts.

Claims (8)

1) Deep sea water is pretreated by at least one method selected from among sand filtration, rapid filtration, microfiltration (MF), immersion membrane filter (SMF) and ultrafiltration (UF) filtration to produce reverse osmosis membrane (RO), nanofiltration membrane Supplying an electrodialysis ion-exchange membrane (ED);
2) Preparing the pretreated deep seawater of step 1) supplied to the reverse osmosis membrane (RO) through a reverse osmosis membrane to produce a concentrated deep seawater and a desalted deep seawater;
2-1) supplying the concentrate deep seawater as a nanofiltration membrane (NF), and supplying a desalted deep seawater as a high hardness water dilution water;
3) The deep-seated deep seawater of step 1) and the concentrated water of step 2-1) supplied to the nanofiltration membrane (NF)
3-1) Using the NF membrane, calcium and magnesium ions were concentrated, and 30-60% of the chloride ion and sodium were removed. Mineral concentrated deep seawater was produced. Supplying an electrodialysis ion exchange membrane (ED) and a nanofiltration membrane (NF);
3-2) Using a nanofiltration membrane (NF), the calcium sulfate and magnesium ions are remained, and sulfate-eliminated mineral water (sulfate concentrated water) ;
3-3) The mineral enriched water supplied back to the NF membrane 3-1) to 3) is subjected to a second or tertiary cycle of the steps of 3-1) and 3-2) A step of preparing a mineral concentrated deep seawater and a sulfate concentrated water with sulfuric acid removed (Sulfate removed water)
4) supplying a desalted deep seawater prepared in step 2) and a mineral concentrated deep seawater prepared in step 3-1) to an electrodialysis ion exchange membrane (ED);
5) activating the electrodialysis ion exchange membrane (ED), supplying the feed water from steps 1) and 4);
5-1) The salt concentration tank contains a function of sodium chloride concentration (Deep sea water brine);
5-2) The hardness concentration tank removes the chlorine ion and the sodium ion, while the calcium ion and the magnesium ion are concentrated, and the mineral enriched desalted water having the mineral content ratio ((magnesium + calcium) / sodium) &Lt; / RTI &gt;
5-3) The mineral enriched desalted water prepared in step 5-2) is supplied to the nanofiltration membrane (NF) in step 3), and the step 3) and the step 4-2) Circulating through the step;
6) The mineral concentrated water from which sulfate ions have been removed in step 3-2) is diluted with reverse osmosis (RO) desalted water in step 2-1) to obtain a water quality satisfying chloride ion and sulfate ion and a step of preparing a high-hardness water having a concentration of not less than 10 mg / L or less. delete delete delete delete delete delete delete

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