KR20170069614A

KR20170069614A - Saltwater desalination system

Info

Publication number: KR20170069614A
Application number: KR1020150177051A
Authority: KR
Inventors: 최준영
Original assignee: 효림산업주식회사
Priority date: 2015-12-11
Filing date: 2015-12-11
Publication date: 2017-06-21

Abstract

The present invention relates to a saline desalination system, and more particularly, to a saline desalination system including a FO mode and a RO mode, wherein the cleansing mode includes a wastewater treatment and a salt concentration of 16,500 to 21,000 mg / Permeable membrane module, which is supplied with the salt-containing groundwater and is diluted with the salt-containing treated water having the salt groundwater concentration of 10,000 to 15,000 mg / L through the osmosis membrane; A first pressurizing pump for supplying sewage treatment water to the osmosis membrane module; And a second pressurizing pump for supplying salt water to the osmosis membrane module, wherein the reverse osmosis mode is a mode in which the treated water diluted in the osmosis membrane module is supplied and the treated water is supplied through the reverse osmosis membrane at a concentration of 300 to 1050 mg a reverse osmosis membrane module for separating the fresh water containing concentrated salts and concentrated water; The reverse osmosis membrane module of the osmosis membrane module and the reverse osmosis membrane module of the osmosis membrane module are desalinated at a temperature of 20 to 25 ° C (room temperature), whereby low-energy and high- To a desalination system capable of producing fresh water having a low salt concentration at a recovery rate.

Description

SALTWATER DESALINATION SYSTEM [0002]

The present invention relates to a brine desalination system capable of producing fresh water of low salt concentration with low energy and high recovery rate.

At present, water shortages are emerging globally, and securing of sustainable water resources is recognized as important. The saline desalination method is an effective technique for solving the water problem caused by the shortage of domestic water, industrial water and agricultural water.

Saltwater desalination refers to the removal of salt dissolved in water to obtain fresh water.

The membrane filtration method is divided into a forward osmosis (FO) method and a reverse osmosis (RO) filtration method in detail. Examples of the method for treating the desalination water include an evaporation method, an electrodialysis method and a membrane filtration method. do.

The salt water desalination method using the positive osmosis method uses the osmotic pressure difference of two solutions having different salt concentrations. Usually, the low concentration solution uses sewage water and artificial rainfall, and the high concentration solution (induction solution) uses sea water do. Due to the difference in osmotic pressure, the low concentration solution permeates through the high concentration solution pressurized through the semipermeable membrane, and is performed in a non-powered state, so that diluted seawater can be produced at a high recovery rate using a small amount of energy. However, in order to use the diluted seawater as a water source, it is necessary to develop an additional process technology for separating the salt present in the diluted seawater.

The salt water desalination method using the reverse osmosis method utilizes a high pressure of osmotic pressure or reverse osmotic pressure, and a raw water supply means (supply pump) for pumping seawater to provide such reverse osmosis pressure is required. Generally, since a high-pressure pump consuming most of the power is used as a raw water supply means, there is a disadvantage that considerable energy is consumed for saline desalination.

In order to overcome the limitations of such a forward osmosis and reverse osmosis system, Korean Patent No. 1,319,411 proposes a hybrid seawater desalination apparatus and method in which a forward osmosis and a reverse osmosis system are fused.

Specifically, the hybrid seawater desalination apparatus includes a first positive osmosis membrane module for diluting high-concentration seawater due to a difference in concentration between sewage-treated water (raw water) and high-concentration seawater (induction solution); A reverse osmosis membrane module for supplying the diluted seawater to separate and discharge the filtered and concentrated water; A low pressure pump for supplying the diluted seawater to the reverse osmosis membrane module; And fouling reduction means for reducing fouling occurring in the first osmosis membrane module.

The above-mentioned technique is characterized in that the salt concentration of the seawater used as the induction solution is about 10,000 to 50,000 mg / l, and the water permeability of the osmosis membrane is excellent due to the large salt concentration difference between the raw water and the seawater. However, Even if sea water is diluted in the membrane module, it is difficult to secure satisfactory low concentration of seawater. Accordingly, in order to separate the diluted seawater into desalination water from the reverse osmosis membrane module, a higher operating pressure is required, which increases energy consumption.

In order to solve the above problems, the present invention uses salt groundwater having a concentration lower than that of seawater as an inductive solution, and uses a pressurizing pump as a driving force to secure a high water permeability of a quasi-osmosis membrane and a water- And a brine desalination system capable of mass production of fresh water having a low salt concentration with low energy by minimizing the operation pressure of a reverse osmosis membrane module.

In order to achieve the above object, the present invention includes a FO mode and a reverse osmosis (RO) mode, wherein the quasi-osmosis mode comprises a step of supplying a saline-containing salt-containing groundwater having a concentration of 16,500 to 21,000 mg / A positive osmosis membrane module which is supplied with a purified osmosis membrane and is diluted with treated water containing the salt having a concentration of the salt groundwater of 10,000 to 15,000 mg / l through the osmosis membrane; A first pressurizing pump for applying a pressure of 0.9 to 2 atm to the sewage treatment water to supply sewage treatment water to the osmosis membrane module; And a second pressurizing pump for supplying salt water to the osmosis membrane module, wherein the reverse osmosis mode is a mode in which the treated water diluted in the osmosis membrane module is supplied and the treated water is supplied through the reverse osmosis membrane at a concentration of 75 to 100 mg a reverse osmosis membrane module for separating the fresh water containing concentrated salts and concentrated water; And a high pressure pump for supplying treated water diluted to the reverse osmosis membrane module by applying a pressure of 19 to 39 atm to the treated water, wherein the forward osmosis membrane of the forward osmosis membrane module and the reverse osmosis membrane module of the forward osmosis membrane module are operated at room temperature &Lt; / RTI > and a saline desalination system.

The positive osmosis mode may further include a pressure regulating valve for regulating the pressure applied by the first pressurizing pump.

The salt concentration of the concentrated water may be 14,000 to 19,000 mg / l.

The brine desalination system may use fresh water separated from the reverse osmosis membrane module as industrial water.

The recovery rate of the fresh water may be 22 to 25% with respect to the treated water.

The brine desalination system can consume 2.4 ~ 2.8 kWh of energy in the production of 1 m3 of fresh water.

The saltwater desalination system according to the present invention is characterized in that saltwater ground water having a salt concentration of 16,500 to 21,000 mg / l is used as an induction solution and the flow rate of the salt groundwater is increased by a pressurizing pump, whereby a high water permeability and a low salt concentration There is an advantage in that it is possible to secure a purified osmosis membrane treatment water of.

Further, since the purified osmosis membrane treated water having a low salt concentration is used as the water to be supplied in the reverse osmosis membrane mode, the present invention has an advantage that fresh water having low salt concentration can be produced with low energy and high recovery rate.

In addition, the present invention has an advantage that concentrated water separated from the reverse osmosis membrane module can be discharged to the sea without further dilution process.

In addition, the present invention is advantageous in that facilities and operation costs can be reduced because the system is simplified by integrating the forward osmosis mode and the reverse osmosis mode integrally.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of a brine desalination system of the present invention.

Hereinafter, a salt water desalination system according to the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of a brine desalination system of the present invention. As shown in FIG. 1, the saline desalination system 10 of the present invention obtains fresh water by removing salinity of a salt dissolved in water or dissolved in water but not evaporated, Mode (30).

More specifically, the normal osmosis mode 20 supplies the treated water with the salt-containing salt groundwater having a concentration of 16,500 to 21,000 mg / l, A forward osmosis membrane module (21) diluted with treated water containing 15,000 mg / l salt; A first pressurizing pump 22 for applying a pressure of 0.9 to 2 atm to the sewage treatment water to supply sewage treatment water to the osmosis membrane module 21; And a second pressurizing pump 23 for supplying a salt groundwater to the osmosis membrane module 21. The reverse osmosis membrane 30 receives the treated water diluted in the osmosis membrane module 21 A reverse osmosis membrane module 31 for separating the treated water into fresh water and concentrated water containing a salt having a concentration of 75 to 100 mg / l through a reverse osmosis membrane 31a; And a high-pressure pump 32 for applying a pressure of 19 to 39 atm to the treated water to supply the treated water diluted to the reverse osmosis membrane module 31.

The forward osmosis mode 20 uses an osmotic gradient of two solutions having different salt concentrations and is composed of a forward osmosis module 21, a first pressurizing pump 22 and a second pressurizing pump 23.

The forward osmosis module (21) receives the sewage treated water and the salt groundwater, and dilutes the salt groundwater with the treated water containing the salt having the concentration of 10,000 to 15,000 mg / l through the osmosis membrane (21a).

That is, in the forward osmosis module 21, pure water in the sewage-treated water flows into the salt groundwater through the purified osmosis membrane (membrane) between the wastewater treatment water and the salt groundwater, so that the salt groundwater is diluted.

The wastewater treatment water is used as the supply water of the forward osmosis module 21 and the salt groundwater is used as a draw solution of the normal osmosis module 21. Sewage treated water and salt ground water are stored in separate sewage treatment water storage tanks 24 and salt ground water storage tanks 25, respectively.

The salt concentration of the salt groundwater is preferably in the range of 10,000 to 15,000 mg / L in consideration of the water permeability of the osmosis membrane 21a, the operation pressure of the reverse osmosis membrane module 31 to be described later, and the salt concentration of fresh water.

As described above, according to the present invention, the osmotic pressure gradient of the forward osmosis membrane 21a is reduced compared with the conventional method using seawater as the inductive solution, but the wastewater treatment water is pressurized by the first pressurizing pump 22, The water permeability of the osmosis membrane 21a is improved due to an increase in the physical water pressure in addition to the osmotic pressure.

The first pressurizing pump 22 maintains a pressure of 0.9 to 2.0 atm, preferably 0.99 to 2 atm. When the pressure of the first pressurizing pump 22 is less than 0.9 atm, the permeation amount of the purified osmosis membrane 21a is small and the salt concentration of the purified osmosis membrane 21a is measured to be 10,000 to 15,000 mg / The operating pressure of the compressor is increased, and reverse osmosis may occur. In the case of more than 2 atm, the fouling of the osmosis membrane 21a may rapidly become frequent, resulting in membrane damage.

Further, the second pressurizing pump 23 supplies the saltwater underground water to the osmosis membrane module 21. The second pressurizing pump 23 preferably maintains a low pressure state such that a sufficient amount of salt groundwater is supplied to the osmosis membrane module 21 and is suitably changed in consideration of the amount of the treated water diluted in the osmosis membrane module 21 It is possible.

Here, the normal osmosis mode 20 may further include a pressure regulating valve 26 for regulating the pressure applied by the first pressurizing pump 22. The pressure regulating valve 26 adjusts the pressure of the first pressurizing pump 22 by controlling the opening and closing degree according to the external control.

Thus, the treated water diluted in the normal osmosis mode 20 is supplied to the reverse osmosis mode 30 to be described later, and the treated water from which the water has been removed is supplied to the wastewater treatment water storage tank 24.

The reverse osmosis mode 30 includes a reverse osmosis module 31 and a high-pressure pump 32 using a high osmotic pressure or reverse osmosis pressure.

The reverse osmosis module 31 receives the treated water diluted by the forward osmosis module 21 and separates the treated water into fresh water and concentrated water through the reverse osmosis membrane 31a.

The treated water diluted in the forward osmosis module (21) is stored in a separate water storage tank (33).

At this time, in order to supply the treated water stored in the treated water storage tank 33 to the reverse osmosis membrane module 31, a high-pressure pump 32 is required as a means for supplying treated water.

The present invention minimizes the operation pressure of the high-pressure pump 32 by using the treated water having a low salt concentration as the supply water of the reverse osmosis membrane mode 30 as compared with the conventionally diluted seawater.

Therefore, in the reverse osmosis membrane module 30 in which the power consumption is usually the highest, the present invention can efficiently perform the reverse osmosis membrane 31a process of the reverse osmosis membrane module 31 using less energy.

Specifically, the high-pressure pump 32 maintains a pressure of 19 to 39 atm, preferably 19.36 to 38.71 atm. When the pressure of the first pressurizing pump is less than 19 atm, the treated water of the reverse osmosis membrane 31a sharply decreases. When the pressure of the first pressurizing pump is more than 39 atm, clogging of the membrane is frequent and chemical cleaning and replacement may occur.

Preferably, the forward osmosis membrane of the forward osmosis membrane module and the reverse osmosis membrane of the reverse osmosis membrane module are operated at room temperature (20-25 ° C).

The fresh water separated from the reverse osmosis membrane module 31 is produced at a low salt concentration and a high recovery rate.

That is, the fresh water has a salt concentration of 75 to 100 mg / L and can be stored in the fresh water storage tank 34 and used as industrial water.

The recovery rate of fresh water may be 22-25% of the treated water. The recovery rate is a ratio of water that is converted into fresh water through the reverse osmosis membrane 31a of the treated water flowing into the reverse osmosis membrane module 31. The recovery rate can be measured through Qf = Qc + Qt and Qt / Qfx100.

Q _f = flow rate into the reverse osmosis membrane 31a

Concentrated in Q _c = reverse osmosis membrane (31a) flow rate

Q _t = treated water flow rate of the reverse osmosis membrane 31a

In addition, 2.4 to 2.8 kWh of energy is consumed in the production of 1㎥ of fresh water. Conventionally, the reverse osmosis membrane 31a using seawater as an inducing solution consumes energy of 4.5 kWh or more when 1 m 3 is produced, so that the seawater desalination system 10 according to the present invention can operate with low energy.

In addition, the concentrated water produced in addition to fresh water has a salt concentration of 14,000 to 19,000 mg / L, which is similar to that of ordinary seawater, so that it can be discharged to the sea by the discharge valve 35 without additional dilution process.

Here, all the solution flowing in the saline desalination system 10 of the present invention can be introduced and discharged through a supply line (not shown).

The present invention is a brine desalination system 10 in which a forward osmosis mode 20 and a reverse osmosis mode 30 are fused. In the normal osmosis mode (20), saltwater ground water having a salt concentration of 16,500 to 21,000 mg / l is used as an induction solution and the flow rate of the salt groundwater is increased by the first pressurizing pump (22) It is possible to produce fresh water at a low energy and a high recovery rate by diluting the salt groundwater with high water permeability and using the salt groundwater diluted in the reverse osmosis mode (30).

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit of the invention as disclosed in the accompanying drawings. And it is obvious that such variations and modifications are included in the appended claims.

< Example 1>

The saltwater desalination system fusing the forward osmosis mode and the reverse osmosis mode of FIG. 1 was used to desalinate the salt groundwater.

Specifically, the saline water and the salt ground water (concentration solution) containing the salt having the concentration of 16,500 mg / l were supplied to the osmosis membrane module to dilute the salt groundwater. At this time, the salt groundwater was supplied by the first pump at about 0.5 atm (pressure) and the sewage water was supplied by the second pressure pump at 2 atm (pressure). Then, the salt groundwater diluted in the osmosis membrane module was supplied to a reverse osmosis membrane module and separated into fresh water and concentrated water. The diluted salt groundwater was supplied by high pressure pump at 34 atm.

< Example 2>

Salt ground water (inductive solution) having a salt groundwater concentration of 17,500 mg / L was supplied to the osmosis membrane module to dilute the salt groundwater.

< Example 3>

Salt ground water (inductive solution) having a salt groundwater concentration of 18,500 mg / L was supplied to the osmosis membrane module to dilute the salt groundwater.

< Example 4>

Salt ground water (inductive solution) having a salt groundwater concentration of 19,500 mg / L was supplied to the osmosis membrane module to dilute the salt groundwater.

< Example 5>

Salt ground water (inductive solution) having a salt groundwater concentration of 21,000 mg / L was supplied to the osmosis membrane module to dilute the salt groundwater.

< Comparative Example 1>

The same procedure as in Example 1 was carried out except that seawater containing a salt having a concentration of 35,000 mg / l instead of salt ground water as an inducing solution was supplied to the osmosis membrane module without using the first pressurizing pump, Water.

< Comparative Example 2>

Salt ground water (inductive solution) having a salt groundwater concentration of 23,000 mg / L was supplied to the osmosis membrane module to dilute the salt groundwater.

< Comparative Example 3>

Salt ground water (inductive solution) having a salt groundwater concentration of 35,000 mg / L was supplied to the osmosis membrane module to dilute the salt groundwater.

< Experimental Example >

Table 1 shows the results of the desalination of salt water and seawater using the systems of the above Examples and Comparative Examples.

division Flow rate (l / hr) Salt concentration (mg / l) Amount of power used for freshwater production
(kWh / m3) sewer
Treated water salt
underground water sea water Treated water
(fresh water) fresh water Concentrated water Example 1 3420 600 65 76 14,090 2.42 Example 2 3420 600 64 82 15,011 2.50 Example 3 3420 600 64 87 15,926 2.58 Example 4 3420 600 64 91 16,835 2.66 Example 5 3420 600 63 99 18,185 2.78 Comparative Example 1 3420 600 53 181 32,829 4.73 Comparative Example 2 3420 600 63 109 19,967 2.96 Comparative Example 3 3420 600 59 166 30,179 4.28

* Influent salt concentration of sewage water: 350 ㎎ / ℓ

As shown in Table 1, it can be seen that the saline desalination systems of Examples 1 to 5 according to the present invention can produce low-salt fresh water with low energy and high recovery rate as compared with Comparative Examples 1 to 3.

In other words, saltwater groundwater having a relatively lower salt concentration than seawater is used, a high water permeability of the osmosis membrane is secured by a pressurizing pump, and a purified osmosis membrane treated water having a low salt concentration is produced. As a result, it was confirmed that the reverse osmosis membrane mode can be operated with low pressure.

10: Salt water desalination system
20: positive osmosis mode
21a: The osmosis membrane
21: The positive osmosis membrane module
22: first pressurizing pump
23: Second pressurizing pump
24: Sewage treated water storage tank
25: Salt ground water storage tank
26: Pressure regulating valve
30: Reverse osmosis mode
31a: reverse osmosis membrane
31: Reverse Osmosis Module
32: High pressure pump
33: treated water storage tank
34: fresh water storage tank
35: discharge valve

Claims

A forward osmosis (FO) mode and a reverse osmosis (RO) mode,
The normal osmosis mode is a process of supplying treated water containing a salt having a concentration of 10,000 to 15,000 mg / l through a quasi-osmotic membrane to a treated water containing a salt having a concentration of 16,500 to 21,000 mg / A dilute positive osmosis membrane module; A first pressurizing pump for applying a pressure of 0.9 to 2 atm to the sewage treatment water to supply sewage treatment water to the osmosis membrane module; And a second pressurizing pump for supplying saline groundwater to the osmosis membrane module,
Wherein the reverse osmosis mode is a reverse osmosis membrane module that receives the treated water diluted in the osmosis membrane module and separates the treated water into fresh water and concentrated water containing a salt having a concentration of 75 to 100 mg / l through a reverse osmosis membrane; And a high-pressure pump for supplying treated water diluted to the reverse osmosis membrane module by applying a pressure of 19 to 39 atm to the treated water,
Wherein the forward osmosis membrane of the forward osmosis membrane module and the reverse osmosis membrane of the reverse osmosis membrane module are operated at room temperature.

The salt water desalination system of claim 1, wherein the forward osmosis mode further comprises a pressure regulating valve for regulating the pressure exerted by the first pressurization pump.

The desalination system of claim 1, wherein the concentrated water has a salt concentration of 14,000 to 19,000 mg / l.

The desalination system of claim 1, wherein the fresh water separated from the reverse osmosis membrane module is used as industrial water.

The saline desalination system according to any one of claims 1 to 4, wherein the recovery rate of the fresh water is 22 to 25% with respect to the treated water.

The desalination system according to any one of claims 1 to 5, wherein the saline desalination system consumes 2.4 to 2.8 kWh of energy in the production of 1 m 3 of fresh water.