CN113651468A - Seawater recycling treatment process - Google Patents
Seawater recycling treatment process Download PDFInfo
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- CN113651468A CN113651468A CN202110745727.2A CN202110745727A CN113651468A CN 113651468 A CN113651468 A CN 113651468A CN 202110745727 A CN202110745727 A CN 202110745727A CN 113651468 A CN113651468 A CN 113651468A
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- 239000013535 sea water Substances 0.000 title claims abstract description 43
- 238000000034 method Methods 0.000 title claims abstract description 30
- 238000004064 recycling Methods 0.000 title claims abstract description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 110
- 238000001223 reverse osmosis Methods 0.000 claims abstract description 62
- 238000001728 nano-filtration Methods 0.000 claims abstract description 30
- 150000003839 salts Chemical class 0.000 claims abstract description 18
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 14
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 12
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000000460 chlorine Substances 0.000 claims abstract description 4
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 4
- 238000004094 preconcentration Methods 0.000 claims abstract description 4
- 102100026982 DCN1-like protein 1 Human genes 0.000 claims abstract 16
- 101000911746 Homo sapiens DCN1-like protein 1 Proteins 0.000 claims abstract 16
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 24
- 239000011780 sodium chloride Substances 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 238000000108 ultra-filtration Methods 0.000 claims description 5
- 239000010802 sludge Substances 0.000 claims description 4
- 238000004140 cleaning Methods 0.000 claims description 3
- 238000005189 flocculation Methods 0.000 claims description 3
- 230000016615 flocculation Effects 0.000 claims description 3
- 239000012528 membrane Substances 0.000 abstract description 33
- 239000003513 alkali Substances 0.000 abstract description 14
- 230000003204 osmotic effect Effects 0.000 abstract description 13
- 239000002994 raw material Substances 0.000 abstract description 7
- 238000005265 energy consumption Methods 0.000 abstract description 6
- 238000000926 separation method Methods 0.000 abstract description 5
- 235000015598 salt intake Nutrition 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 7
- 230000004907 flux Effects 0.000 description 6
- 238000010612 desalination reaction Methods 0.000 description 5
- 239000013505 freshwater Substances 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- 239000012267 brine Substances 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000012510 hollow fiber Substances 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 2
- 238000004659 sterilization and disinfection Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 239000005708 Sodium hypochlorite Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000003651 drinking water Substances 0.000 description 1
- 235000020188 drinking water Nutrition 0.000 description 1
- 238000000909 electrodialysis Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000005188 flotation Methods 0.000 description 1
- 230000015784 hyperosmotic salinity response Effects 0.000 description 1
- 230000002779 inactivation Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000001954 sterilising effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/08—Seawater, e.g. for desalination
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/04—Disinfection
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention discloses a seawater recycling treatment process, which comprises the following steps that seawater enters a nanofiltration unit for salt separation treatment after pretreatment; the nanofiltration produced water obtained by nanofiltration treatment enters a reverse osmosis unit for preconcentration, and the obtained reverse osmosis produced water is sterilized and disinfected to be used as domestic water; and the reverse osmosis concentrated water obtained by the reverse osmosis treatment enters an SCRO unit for deep concentration, a part of the SCRO concentrated water obtained by the treatment of the SCRO unit is used for reducing the osmotic pressure difference at two sides of a membrane of the SCRO unit and finally flows back to the reverse osmosis unit together with the SCRO produced water for secondary concentration, and the other part of the SCRO concentrated water is used as a raw material of the chlor-alkali industry and enters an electrolysis unit for electrolysis to produce sodium hydroxide and chlorine. The seawater recycling treatment process realizes the high concentration of seawater under the condition of low energy consumption, and simultaneously, the produced concentrated water can be used as the raw material of the chlor-alkali industry, so that the marine pollution and the raw salt consumption of the chlor-alkali industry are effectively reduced, and the seawater recycling is realized.
Description
Technical Field
The invention relates to the technical field of seawater treatment, in particular to a seawater recycling treatment process.
Background
The shortage of fresh water resources in China is increasingly the bottleneck of development along with the rapid development of economy due to the fact that the fresh water resources are poor and unevenly distributed. The resource utilization of seawater desalination is an important means for solving the problems. The current common seawater desalination technologies are mainly divided into membrane methods (reverse osmosis and electrodialysis) and thermal methods (multi-stage flash evaporation, low-temperature multi-effect and vapor compression distillation), wherein the reverse osmosis membrane method is the most common seawater desalination method in China and is commonly used.
The conventional reverse osmosis membrane seawater desalination process mainly comprises pretreatment, reverse osmosis and disinfection discharge, wherein a common method of the pretreatment comprises sterilization inactivation (sodium hypochlorite is added), air flotation, coagulation, precipitation, filtration and the like, pretreated seawater (TDS is approximately equal to 32000 mg/L-35000 mg/L) enters a reverse osmosis unit for concentration, the recovery rate range is approximately 35-60%, final concentrated brine (TDS is approximately equal to 50000 mg/L-87500 mg/L) after reverse osmosis treatment is directly discharged to the sea, and finally produced water is disinfected and then used as stable water supply such as coastal resident drinking water and industrial boiler water supplement.
The reverse osmosis membrane seawater desalination process has the following problems: the discharge of strong brine after membrane concentration can cause the increase of ocean salinity, and particularly, the seawater renewal speed in a semi-closed sea area is slow, so that the salinity distribution is uneven. Too high salinity can seriously affect some marine organisms with poor salt tolerance, destroy ecological balance and cause a series of uncontrollable negative factors.
In view of the above, the present inventors have invented a seawater recycling process.
Disclosure of Invention
The invention aims to provide a seawater recycling treatment process, which can realize high concentration of seawater under the condition of low energy consumption, and simultaneously, the produced concentrated water can be used as a raw material in the chlor-alkali industry, so that the marine pollution and the raw salt consumption in the chlor-alkali industry are effectively reduced, and the seawater recycling utilization is realized.
In order to achieve the purpose, the invention adopts the following technical scheme: a seawater recycling treatment process comprises the following steps:
s1: the seawater enters a nanofiltration unit after pretreatment, nanofiltration produced water with the solute mainly comprising sodium chloride and nanofiltration concentrated water containing divalent salt and soluble organic matters are obtained, wherein the nanofiltration concentrated water is directly discharged to the ocean,
s2: the nanofiltration produced water enters a reverse osmosis unit for pre-concentration to obtain reverse osmosis produced water and reverse osmosis concentrated water, wherein the reverse osmosis produced water is sterilized and disinfected to be used as domestic water,
s3: the reverse osmosis concentrated water enters an SCRO unit for concentration to obtain SCRO produced water and SCRO concentrated water, a part of the SCRO concentrated water and the original salt are mixed until the concentration of sodium chloride in the solution reaches a certain value and then enter an electrolysis unit, sodium hydroxide and chlorine are produced by electrolysis, the other part of the SCRO concentrated water flows back to the water production side of the SCRO unit and is mixed with the SCRO produced water and flows back to the front end of the reverse osmosis unit, and the mixed water and the nanofiltration produced water enter the reverse osmosis unit after being mixed.
Further, the pretreatment in S1 includes a self-cleaning filter, flocculation, and ultrafiltration in this order.
Further, the pretreated seawater in S1 has a sludge density index of less than 3.
Further, the concentration of the reverse osmosis concentrated water in S2 was 7%.
Further, the concentration of the SCRO concentrate in S3 was 26%.
Furthermore, the concentration of sodium chloride in the solution after the concentrated water of the SCRO in S3 is mixed with the original salt is more than 310 g/L.
Further, the reverse osmosis unit and the SCRO unit share a high pressure pump, and the operating pressure of the high pressure pump does not exceed 70 bar.
After the technical scheme is adopted, the invention has the following advantages:
1. the seawater recycling treatment process removes scaling factors and soluble organic matters in seawater through nanofiltration, effectively reduces scaling risk of a back-end system, simultaneously enables final concentrated water to meet the water quality requirement of electrolysis, and is beneficial to the stability of electrolysis equipment and the improvement of the purity of electrolysis products;
2. the seawater is concentrated by the combination of the reverse osmosis unit and the SCRO unit, so that the final concentrated water meets the feeding requirement of the electrolysis unit, and meanwhile, the high concentration can be realized under the condition of low energy consumption, and the energy consumption is effectively reduced;
3. the generated concentrated water is used as a raw material in the chlor-alkali industry, so that zero discharge of the concentrated water is realized, the damage to the marine environment is reduced, and meanwhile, the consumption of raw salt in the chlor-alkali industry can be effectively reduced, so that the resource utilization of seawater is realized.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Examples
The invention discloses a seawater recycling treatment process, which can be used for producing fresh water as domestic water and producing concentrated water for use as a raw material in the chlor-alkali industry, realizes zero discharge of the concentrated water, reduces damage to the marine environment, and can effectively reduce the consumption of raw salt in the chlor-alkali industry, thereby realizing the recycling of seawater. The whole seawater recycling treatment process specifically comprises the following steps:
s1: the seawater enters a nanofiltration unit after pretreatment, nanofiltration produced water with the solute mainly comprising sodium chloride and nanofiltration concentrated water containing divalent salt and soluble organic matters are obtained, wherein the nanofiltration concentrated water is directly discharged to the ocean,
s2: the nanofiltration produced water enters a reverse osmosis unit for pre-concentration to obtain reverse osmosis produced water and reverse osmosis concentrated water, wherein the reverse osmosis produced water is sterilized and disinfected to be used as domestic water,
s3: the Reverse Osmosis concentrated water enters an SCRO (Special Channel Reverse Osmosis) unit for concentration to obtain SCRO produced water and SCRO concentrated water, a part of the SCRO concentrated water is mixed with a proper amount of original salt until the concentration of sodium chloride in the solution reaches a certain value and then enters an electrolysis unit for electrolysis to produce sodium hydroxide and chlorine, namely the part of the SCRO concentrated water is used as a raw material in the chlor-alkali industry; and the other part of the SCRO concentrated water flows back to the water production side of the SCRO unit, is mixed with the SCRO produced water and flows back to the front end of the reverse osmosis unit, and then enters the reverse osmosis unit after being mixed with the nanofiltration produced water.
Wherein the pretreatment in S1 comprises self-cleaning filter, flocculation and ultrafiltration in sequence, and the sludge density index of the pretreated seawater is less than 3, thus meeting the requirement of the water quality of the inlet water of the subsequent membrane system. The Sludge Density Index (SDI) is one of important indexes for measuring the water inflow of the reverse osmosis system and is also a main means for detecting whether the water outflow of the pretreatment system meets the requirements of the reverse osmosis water inflow. The size of the device is important for the service life of a reverse osmosis system, the device represents the content of particles, colloid and other objects which can block various water purification devices in water, and corresponding water purification technologies or devices can be selected by measuring SDI values. Among them, the hollow fiber membrane module generally requires an SDI value of about 3, and the roll-up module generally requires an SDI value of about 5.
Nanofiltration (NF) is a pressure-driven membrane separation process between reverse osmosis and ultrafiltration, and has separation performance between reverse osmosis and ultrafiltration, allowing some inorganic salts and some solvents to permeate through the membrane, thereby achieving separation. The pore diameter range of the nanofiltration membrane is about a few nanometers, the nanofiltration membrane has the characteristics of low operating pressure and high rejection rate of divalent ions, and can effectively intercept scaling factors such as calcium, magnesium and the like in seawater and reduce scaling risks in the subsequent concentration and electrolysis processes; meanwhile, the retention rate of the concentrated water for sulfate radicals reaches 90-99%, and the content of the sulfate radicals can be obviously reduced, so that the final concentrated water reaches the standard of liquid salt for alkali preparation; in addition, the nanofiltration intercepts most of divalent salts (such as sulfate) and soluble organic matters, and the seawater is purified until the main solute of the nanofiltration produced water is sodium chloride, so that the final concentrated water meets the water quality requirement of the inlet water of the electrolysis unit.
The nanofiltration produced water enters a reverse osmosis unit and an SCRO unit for concentration treatment, so that the final concentrated water can be used as a raw material in the chlor-alkali industry. The nanofiltration produced water is firstly pre-concentrated by reverse osmosis, the reverse osmosis produced water is sterilized and disinfected to be used as domestic water, and the reverse osmosis produced water is also the only final fresh water in the whole process; the reverse osmosis concentrated water enters the SCRO unit for deep concentration.
The SCRO, a special flow path rolled Reverse Osmosis membrane, employs an Osmosis Assisted Reverse Osmosis (OARO) technique, which reduces an osmotic pressure difference between both sides of a membrane by refluxing a part of a concentrate to a low pressure side of the Reverse Osmosis membrane, thereby improving a membrane flux of the Reverse Osmosis membrane under the same conditions. Wherein, reverse osmosis membrane belongs to selective semi-permeable membrane, and the diffusion coefficient of membrane to the hydrone is higher than other solutes far away. Under the premise of no pressure, water molecules can be transferred from the side with low osmotic pressure to the side with high osmotic pressure, and the permeation rate is higher when the osmotic pressure difference between the two sides is higher. In the reverse osmosis process, a pressure larger than the osmotic pressure difference of two sides of the membrane is applied to one side with high osmotic pressure so that water molecules are transferred from the one side with high osmotic pressure to the one side with low osmotic pressure, thereby realizing the separation of water and solute, and the membrane flux formula of the reverse osmosis process is as follows:
J=A*（△P-△π）
wherein J is membrane flux, A is a dissolution diffusion coefficient, DeltaP is a pressure difference at two sides of the membrane, and DeltaPi is a permeation pressure difference at two sides of the membrane. From this membrane flux equation: when the osmotic pressure difference between two sides of the membrane is larger, the required pressure in the concentration process is also larger, and the OARO can obtain higher membrane flux of the reverse osmosis membrane under the condition of applying the same pressure by reducing the osmotic pressure difference between two sides of the membrane, namely, the same level of membrane flux can be obtained by applying lower pressure through the OARO technology.
The membrane component type of the SCRO unit is a hollow fiber type, a part of SCRO concentrated water flows back to the water production side of the SCRO unit, so that the osmotic pressure difference at two sides of the membrane can be obviously reduced, the concentration multiple can be obviously improved under the condition of lower operation pressure, the operation energy consumption of concentration is effectively reduced, the SCRO concentrated water flows back to the water production side of the SCRO unit to reduce the osmotic pressure difference and is finally mixed with the SCRO produced water, and the mixed solution flows back to the front end of the reverse osmosis system and enters the reverse osmosis system again for treatment due to higher concentration (about 3%).
The concentration of the reverse osmosis concentrated water is 7%, namely TDS of the reverse osmosis concentrated water is approximately equal to 70000mg/L, wherein TDS refers to Total Dissolved Solids (TDS), and the concentration of the SCRO concentrated water can reach 26% (TDS is approximately equal to 260000 mg/L).
In this embodiment, the concentration of sodium chloride in the solution after the SCRO concentrated water and the raw salt in S3 are mixed is greater than 310g/L, so that the solution meets the water quality requirement of the chlor-alkali industry, and the specific amount of the raw salt can be determined according to the concentration of sodium chloride in the solution required by the actual production. Wherein, according to QB/T1879-2001 standard, the lowest standard of the liquid salt for preparing alkali is that the concentration of sodium chloride is more than 260g/L, and the concentration of sulfate is less than 15 g/L, which is detailed in Table 1.
TABLE 1 QB/T1879-2001 liquid salt standards
In the embodiment, the reverse osmosis unit and the SCRO unit are connected in series and share one high-pressure pump, the operating pressure of the high-pressure pump does not exceed 70bar, and the energy consumption of the whole system is low.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (7)
1. A seawater recycling treatment process is characterized in that: the method comprises the following steps:
s1: the seawater enters a nanofiltration unit after pretreatment, nanofiltration produced water with the solute mainly comprising sodium chloride and nanofiltration concentrated water containing divalent salt and soluble organic matters are obtained, wherein the nanofiltration concentrated water is directly discharged to the ocean,
s2: the nanofiltration produced water enters a reverse osmosis unit for pre-concentration to obtain reverse osmosis produced water and reverse osmosis concentrated water, wherein the reverse osmosis produced water is sterilized and disinfected to be used as domestic water,
s3: the reverse osmosis concentrated water enters an SCRO unit for concentration to obtain SCRO produced water and SCRO concentrated water, a part of the SCRO concentrated water and the original salt are mixed until the concentration of sodium chloride in the solution reaches a certain value and then enter an electrolysis unit, sodium hydroxide and chlorine are produced by electrolysis, the other part of the SCRO concentrated water flows back to the water production side of the SCRO unit and is mixed with the SCRO produced water and flows back to the front end of the reverse osmosis unit, and the mixed water and the nanofiltration produced water enter the reverse osmosis unit after being mixed.
2. The seawater recycling treatment process of claim 1, wherein: the pretreatment in S1 sequentially comprises self-cleaning filter, flocculation and ultrafiltration.
3. The seawater recycling treatment process of claim 1, wherein: the sludge density index of the pretreated seawater in the S1 is less than 3.
4. The seawater recycling treatment process of claim 1, wherein: the concentration of the reverse osmosis concentrated water in the S2 is 7%.
5. The seawater recycling treatment process of claim 1, wherein: the concentration of the concentrated water of SCRO in S3 was 26%.
6. The seawater recycling treatment process of claim 1, wherein: the concentration of sodium chloride in the solution after the concentrated water of the SCRO in the S3 is mixed with the original salt is more than 310 g/L.
7. The seawater recycling treatment process of claim 1, wherein: the reverse osmosis unit and the SCRO unit share one high-pressure pump, and the operating pressure of the high-pressure pump does not exceed 70 bar.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114108008A (en) * | 2021-12-07 | 2022-03-01 | 临涣水务股份有限公司 | Method for preparing sodium hypochlorite by utilizing reverse osmosis concentrated water |
| CN114223906A (en) * | 2021-12-17 | 2022-03-25 | 炎黄先农(宁波)智慧科技有限公司 | Mineral element agent and preparation method and application thereof |
| CN114573174A (en) * | 2022-03-23 | 2022-06-03 | 苏州乔发环保科技股份有限公司 | Inorganic salt treatment method |
| CN114870633A (en) * | 2022-05-18 | 2022-08-09 | 北京万邦达环保技术股份有限公司 | Process for enriching lithium in salt lake brine |
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| WO2007132477A1 (en) * | 2006-05-11 | 2007-11-22 | Raman Ahilan | A pretreatment process for the saline water feeds of desalination plants |
| CN105906109A (en) * | 2016-07-06 | 2016-08-31 | 北京大井易通科技发展有限公司 | Short-process seawater desalination pretreatment technique |
| CN109650608A (en) * | 2017-10-12 | 2019-04-19 | 华东理工大学 | It is a kind of using chemical method-nanofiltration-it is reverse osmosis-electrodialysis integrate concentrated seawater softening and concentration technology |
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| CN114108008A (en) * | 2021-12-07 | 2022-03-01 | 临涣水务股份有限公司 | Method for preparing sodium hypochlorite by utilizing reverse osmosis concentrated water |
| CN114223906A (en) * | 2021-12-17 | 2022-03-25 | 炎黄先农(宁波)智慧科技有限公司 | Mineral element agent and preparation method and application thereof |
| CN114573174A (en) * | 2022-03-23 | 2022-06-03 | 苏州乔发环保科技股份有限公司 | Inorganic salt treatment method |
| CN114870633A (en) * | 2022-05-18 | 2022-08-09 | 北京万邦达环保技术股份有限公司 | Process for enriching lithium in salt lake brine |
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