WO2022246823A1

WO2022246823A1 - Concentrated brine deep purification device and process

Info

Publication number: WO2022246823A1
Application number: PCT/CN2021/096897
Authority: WO
Inventors: 钱媛媛; 张行; 冯晓荟; 周海; 尹永生; 付振华
Original assignee: 麦王环境技术股份有限公司
Priority date: 2021-05-28
Filing date: 2021-05-28
Publication date: 2022-12-01
Also published as: CN115038671A

Abstract

The present invention relates to a concentrated brine deep purification device and process. The device comprises a raw water tank, an organic separation unit, a primary salt separation unit, and a secondary salt separation unit. The organic separation unit comprises an organic reaction tank and a membrane separation device; the organic reaction tank provides a mixing reaction space for concentrated brine and a combined agent; and the membrane separation device is a roll-type microfiltration membrane, which is used for removing organic components from the concentrated brine. The present invention can treat industrial wastewater having a high concentration and high organic content with TDS in a range of 50000 mg/L to 150000 mg/L and COD ≥ 500 mg/L, allowing removal of organic components by a simple and economical method before salt separation of concentrated brine, thereby allowing obtaining of a relatively pure salt product, reducing the scale and the invested operation cost of a salt separation system, and improving the economic benefits of concentrated brine wastewater treatment.

Description

A concentrated brine deep purification device and process

technical field

The invention relates to the field of purification and utilization of saline wastewater resources, in particular to a purification device and a treatment process for separating salt and organic matter in high-concentration saline wastewater.

Background technique

With the continuous development of the economy, people have put forward higher requirements for a better living environment. Due to the characteristics of "reverse distribution" of my country's energy structure and water resources, there are problems such as shortage of water resources, serious water pollution, and low water environment capacity in Northwest China, which is rich in coal and oil resources. Therefore, in areas such as coal chemical industry, medicine, It is very necessary to implement deep reuse of production wastewater in industrial fields with "high water consumption and high energy consumption" such as coal-fired power plants.

In the process of reclaimed water reuse, the high-concentration saline wastewater produced by concentration not only contains salts such as chloride salts, sulfates, and nitrates that can be recycled and reused, but also contains complex and difficult-to-treat organic pollutants. Before the salt separation treatment of such wastewater, the organic matter in the water needs to be removed as much as possible, so that pure monovalent and divalent salt products with high utilization value can be obtained in the subsequent salt separation process.

At present, the removal methods of organic matter in wastewater include mature methods such as coagulation, biological oxidation, and advanced oxidation. However, high-concentration salt can inhibit the growth of microorganisms and even cause toxicity to them, thus making it difficult to apply biological oxidation technology in the treatment of high-salt wastewater; while advanced oxidation processes such as Feton oxidation, electrocatalytic oxidation, and ozone oxidation Equipment investment costs and operation and maintenance costs are high. For industrial high-salt wastewater with low added value and huge treatment volume, it lacks cost advantages and is difficult to be widely used. Coagulation is a widely used wastewater treatment process, but up to now, the mechanism of chemical coagulation is still not completely clear. etc. will affect the coagulation effect. At present, the generally recognized coagulation mechanism includes: compression electric double layer theory, adsorption bridging theory and net trapping theory.

Therefore, there is an urgent need to provide a wastewater treatment device and process for treating high-salt wastewater in industries such as coal chemical industry to obtain pure monovalent and divalent salts with high added value, and to realize zero discharge of wastewater. .

Contents of the invention

In order to solve the above-mentioned problems in the prior art, the present invention provides a concentrated brine deep purification device and process, specifically as follows:

A concentrated brine deep purification device is provided, the purification device includes a raw water tank, an organic separation unit, a primary salt separation unit and a secondary salt separation unit, and the units are connected through pipelines and liquid pumps.

The organic separation unit includes an organic reaction tank and a membrane separation device; the raw water tank is used to receive and store the concentrated brine to be purified, which is connected with the organic reaction tank through a pipeline and an inlet pump; the organic reaction tank provides the concentrated brine and The mixing reaction space of the combined medicament; the water outlet of the organic reaction tank is connected to the membrane separation device through the pipeline and the membrane separation device inlet pump, and the membrane separation device is a roll-type microfiltration membrane, which is used to remove the organic matter in the concentrated brine. point.

The organic separation unit also includes a first intermediate water tank, a sludge dewatering device and a chemical cleaning device; the water inlet of the first intermediate water tank communicates with the water outlet of the membrane separation device for storing The concentrated brine with organic components removed; the sludge dewatering device is connected to the sludge discharge port of the membrane separation device, and is used to dewater the sludge containing organic matter and combined medicaments retained by the membrane separation device; the The chemical cleaning device is connected to the water inlet of the membrane separation device through a pipeline, and is used for supplying chemical cleaning agent to the membrane separation device during the cleaning stage.

The primary salt separation unit includes a security filter, a primary salt separation device, a second intermediate pool and a brine pool; the water outlet of the first intermediate pool is connected to the security filter through a pipeline and a lift pump of the primary salt separation device The water outlet of the security filter is connected to the water inlet of the first-stage salt-separation device through the pipeline and the high-pressure pump of the first-stage salt-separation device to supply high-pressure concentrated brine to the first-stage salt-separation device; the first-stage salt-separation device is a sodium filter membrane; the water inlet of the security filter is connected with a scale inhibitor dosing device; the water inlet and outlet of the first-stage salt separation device are connected with a membrane cleaning device; the concentrated water (referring to the intercepted The water) is connected to the water inlet of the second intermediate pool through the pipeline; the produced water (referring to the permeated water) of the first-stage salt separation device is connected to the brine pool through the pipeline.

The material of the nanofiltration membrane used in the first-stage salt separation device is selected from one or a combination of polyamides, polysulfones, and cellulose acetates.

The secondary salt separation unit includes a secondary salt separation device and a Glauber's salt pond; the outlet water of the second intermediate pool is connected to the water inlet of the secondary salt separation device through a pipeline and the lift pump of the secondary salt separation device; The salt separation device is a freezing and crystallization device, which freezes and crystallizes the concentrated water (mainly containing dibasic sodium sulfate) produced by the first-stage salt separation device, and the generated Glauber's salt (Na ₂ SO ₄ ·10H ₂ O crystal) is transported to and delivery pumps to the Glauber's salt pool, and the mother liquor produced by the secondary salt separation device is transported to the raw water tank through pipelines.

Preferably, a pretreatment unit is further included between the organic reaction tank and the raw water tank, and the pretreatment unit is used to remove total hardness and soluble silicon in the concentrated brine.

As shown in Figure 2, a method for purifying concentrated brine based on the aforementioned concentrated brine advanced purification device is provided, including the following steps:

S1. Transport the concentrated salt wastewater to be treated to the original water tank;

S2. Transport the waste water in the raw water tank to the organic separation unit; the concentrated brine containing organic components from the raw water tank is first transported to the organic reaction tank, where it is mixed with the combination agent added to the organic reaction tank , and a coagulation + adsorption combined reaction occurs, and then transported to an organic separation device composed of a roll-type microfiltration membrane; the organic component after the reaction is intercepted by the roll-type microfiltration membrane, thereby being removed from the concentrated brine;

S3. After being treated by the organic separation unit, the produced water and sludge are transported to the primary salt separation unit and sludge dehydration device respectively;

S4. After being treated by the primary salt separation unit, the product water and concentrated water are sent to the brine pool and the secondary salt separation unit respectively; the monovalent salt in the concentrated brine can pass through the nanofiltration membrane, while the divalent salt is absorbed by the nanofiltration membrane Retention, so as to separate the monovalent salt and divalent salt in the concentrated brine; the monovalent salt that passes through the nanofiltration membrane is sent to the brine pool; the divalent salt that is intercepted by the nanofiltration membrane is sent to the secondary salt separation unit;

S5. After being treated by the secondary salt separation device, the generated Glauber's salt is transported to the Glauber's salt pond, and the mother liquor is transported to the raw water tank; the secondary salt separation device freezes and crystallizes the divalent salt solution produced by the primary salt separation device to generate decahydrate Sodium sulfate crystals, i.e. Glauber's salt; the Glauber's salt is transported to the Glauber's salt tank, and the mother liquor produced during the crystallization process is transported to the raw water tank to be mixed with the concentrated brine to be treated, so as to increase the overall yield of Glauber's salt.

The crystallization temperature of the secondary salt separation unit is -15°C to 5°C.

Compared with the prior art, the present invention can at least achieve the following beneficial effects:

In the present invention, the organic components of the concentrated brine are removed before the salt separation treatment, and the organic components in the concentrated brine are effectively removed through the treatment method of microfiltration membrane + combined agent; through multiple comparisons In the experiment, it was creatively found that the combination of wood activated carbon powder and polyferric coagulant can achieve better COD removal effect, and after industrial scale-up application, no need to add additional flocculant;

The present invention finds that when the polymeric aluminum silicate coagulant is used alone, it has almost no effect on the removal of COD in the concentrated brine. Based on the combination of wood activated carbon powder and polyiron, the COD removal rate is further greatly improved;

The organic separation unit of the present invention can achieve a COD removal rate of more than 30% under a certain ratio of adsorbent and coagulant. The organic separation unit of the present invention can further cooperate with subsequent nanofiltration and crystallization treatment to achieve The total salt recovery rate in concentrated salt industrial wastewater is ≥90%, and the COD removal rate is ≥50%;

The present invention can be aimed at the treatment of high-concentration and high-organic-content industrial wastewater with a TDS of 50,000 mg/L-150,000 mg/L and a COD ≥ 500 mg/L, and the creative discovery of the combination agent can allow a simple and economical method to separate concentrated brine The former organic components are removed, thus allowing to obtain relatively pure salt products, reducing the scale of the salt separation system and investment and operation costs, and improving the economic benefits of concentrated salt wastewater treatment.

Description of drawings

Fig. 1 is the structural diagram of deep purification device of the present invention;

Fig. 2 is a flowchart illustrating the purification of concentrated brine by the purification device.

Detailed ways

As shown in Figure 1, a concentrated brine depth purification device is provided, the purification device includes a raw water tank (101), an organic separation unit, a primary salt separation unit and a secondary salt separation unit, each unit is connected through a pipeline and a liquid pump connect.

The organic separation unit includes an organic reaction tank (103) and a membrane separation device (105); the raw water tank (101) is used to receive and store the concentrated brine to be purified, which reacts with the organic through a pipeline and an inlet pump (102) The tank (103) is connected; the organic reaction tank (103) provides a mixed reaction space of concentrated brine and combined medicament; the water outlet of the organic reaction tank (103) is separated from the membrane by a pipeline and a membrane separation device inlet pump (104) The device (105) is connected, and the membrane separation device (105) is a roll-type microfiltration membrane, which is used to remove organic components in concentrated brine.

The organic separation unit also includes a first intermediate tank (106), a sludge dewatering device (107) and a chemical cleaning device (108); the water inlet of the first intermediate tank and the outlet of the membrane separation device (105) The water port is connected, and is used to store the concentrated brine that has removed organic components through the membrane separation device (105); the sludge dewatering device (107) is connected with the sludge discharge port of the membrane separation device (105), for Dewater the sludge containing organic matter and combined medicaments retained by the membrane separation device (105); the chemical cleaning device (108) is connected to the water inlet of the membrane separation device through a pipeline for It is supplied with cleaning chemicals during the cleaning phase of the

The primary salt separation unit includes a security filter (202), a primary salt separation device (204), a second intermediate pool (205) and a brine pool (206); the water outlet of the first intermediate pool (106) The lifting pump (201) of the first-stage salt separation device is connected to the security filter (202) through the pipeline, and the water outlet of the security filter (202) is connected to the first-stage salt separation device through the pipeline and the high-pressure pump (203) of the first-stage salt separation device. The water inlet of (204) is connected to supply high-pressure concentrated brine to the first-stage salt separation device (204); the first-stage salt separation device (204) is a nanofiltration membrane; the water inlet of the security filter (202) is connected with a scale inhibitor dosing device (207); the water inlet and outlet of the primary salt separation device (204) are connected to the membrane cleaning device (208); the concentrated water (referred to as the The intercepted water) is connected with the water inlet of the second intermediate pool (205) through the pipeline; the produced water (referring to permeate water) of the primary salt separation device (204) is connected with the brine pool (206) through the pipeline.

The material of the nanofiltration membrane used in the first-stage salt separation device (204) is selected from one or a combination of polyamides, polysulfones, and cellulose acetates.

The secondary salt separation unit includes a secondary salt separation device (302) and a Glauber's salt pond (304); the outlet water of the second intermediate pool (205) passes through the pipeline and the secondary salt separation device lift pump (301) and the secondary salt separation device. The water inlet of the salt separation device (302) is connected; the secondary salt separation device (302) is a freezing and crystallization device, which freezes and crystallizes the concentrated water (mainly containing dibasic sulfuric acid sodium salt) produced by the primary salt separation device, The generated Glauber's salt (Na ₂ SO ₄ ·10H ₂ O crystal) is sent to the Glauber's salt pool (304) through the conveyor belt and the pump (303), and the mother liquor produced by the secondary salt separation device (302) is sent to the raw water tank (101 ).

Preferably, a pretreatment unit is further included between the organic reaction tank (103) and the raw water tank (101), and the pretreatment unit is used to remove total hardness and soluble silicon in the concentrated brine.

S1. Transport the concentrated salt wastewater to be treated to the raw water tank (101);

S2. The waste water in the raw water tank (101) is delivered to the organic separation unit; the strong brine containing organic components from the raw water tank (101) is first delivered to the organic reaction tank (103), where it is added to the organic reaction tank (103). The combined reagents in the organic reaction tank (103) are mixed, and coagulation + adsorption combined reaction occurs, and then transported to the organic separation device (105) composed of roll-type microfiltration membrane; the reacted organic components are collected by the roll Type microfiltration membrane interception, thereby being removed from the concentrated brine;

S3. After being treated by the organic separation unit, the produced water and sludge are transported to the primary salt separation unit and the sludge dehydration device (107);

S4. After being treated by the primary salt separation unit, the product water and concentrated water are sent to the brine pool (206) and the secondary salt separation unit respectively; the monovalent salt in the concentrated brine can pass through the nanofiltration membrane, while the divalent salt is absorbed by the The nanofiltration membrane is intercepted, so that the monovalent salt and the divalent salt in the concentrated brine are separated; the monovalent salt that passes through the nanofiltration membrane is transported to the brine pool (206); the divalent salt that is intercepted by the nanofiltration membrane The salt is delivered to the secondary salt separation unit;

S5. After being treated by the secondary salt separation device (302), the generated Glauber's salt is transported to the Glauber's salt pond (304), and the mother liquor is transported to the raw water tank (101); The divalent salt solution produced in 204) is frozen and crystallized to generate sodium sulfate decahydrate crystals, i.e. Glauber's salt; the Glauber's salt is transported to the Glauber's salt pool (304), and the mother liquor produced during the crystallization process is transported to the raw water tank (101) and treated concentrated brine to increase the overall yield of Glauber's salt.

Organic separation unit process screening experiment

The organic separation unit in the aforementioned concentrated brine advanced purification device was used to treat typical coal chemical concentrated brine wastewater, and the treatment effect under different process conditions was investigated. The salt content of the concentrated salt wastewater is 5.1%, wherein the main salts are sodium sulfate and sodium chloride, sulfate radical 8250mg/L, chloride radical 23850mg/L, total hardness 10mg/L, soluble silicon 20mg/L.

The coal chemical concentrated brine is first injected into the raw water tank (101) for temporary storage, and then the total hardness and soluble silicon in the concentrated brine are removed by the pretreatment device; the pretreated concentrated brine is transported to the organic reaction tank (103) .

Example 1

Adsorbent + single-component coagulant + microfiltration membrane filtration (membrane pore size is 0.3 μm) experiment.

Polyferric (i.e. polyferric sulfate coagulant PFS) and powdered activated carbon adsorbent are added in the organic reaction tank (103); the activated carbon powder adsorbent is: TY-120 (wood charcoal for sugar, 200 mesh, Methylene blue decolorization power > 120ml/g, Shanghai Activated Carbon Factory Co., Ltd.) or MZ-800 (coal-based carbon, 200 mesh, iodine value: 800mg/g, Zhengzhou Zhulin Activated Carbon Development Co., Ltd.).

The COD removal rate before and after the reaction was investigated respectively according to the following conditions:

A. The dosage is: TY-120 powdered carbon 500mg/L, poly-iron PFS-250mg/L; the influent COD is 1061.4mg/L, the effluent COD is 813.4mg/L, and the COD removal rate is 23.4%;

B. The dosage is: MZ-800 powdered carbon 500mg/L, poly-iron PFS-250mg/L; the influent COD is 1061.4mg/L, the effluent COD is 892.8mg/L, and the COD removal rate is 15.9%;

C. The dosage is: TY-120 powdered carbon 750mg/L, poly-iron PFS-250mg/L, influent COD 952.3mg/L, effluent COD 724.2mg/L, COD removal rate 24.9%;

Example 2

Adsorbent + single-component coagulant + microfiltration membrane filtration (membrane pore size 0.1 μm) experiment.

The dosage is: TY-120 powdered charcoal 750mg/L, poly-iron PFS-250mg/L, influent COD 1126.9mg/L, effluent COD 873mg/L, COD removal rate 26.3%.

Example 3

Adsorbent + compound coagulant, microfiltration membrane filtration (membrane pore size 0.3μm) experiment.

The dosage is: TY-120 powdered carbon 500mg/L, polyferric PFS-50mg/L, polyaluminum iron silicate-50mg/L, influent COD 248mg/L, effluent COD 156mg/L, COD removal rate 37%.

Comparative example 1

Adsorbent + microfiltration membrane filtration (membrane pore size 0.3 μm) experiment.

The dosage is: TY-120 powdered carbon 750mg/L, influent COD 1539mg/L, effluent COD 1325mg/L, COD removal rate 14.0%.

Comparative example 2

Coagulant + microfiltration membrane filtration (membrane pore size 0.3 μm) experiment.

A. The dosage is: Polyferric PFS-300mg/L, the influent COD is 153mg/L, the effluent COD is 120mg/L, and the COD removal rate is 21.6%;

B. Polymerized aluminum iron silicate - 300mg/L, COD is 153mg/L, effluent COD is 151mg/L, COD removal rate is 1.3%.

Separation experiment of deep purification device

Example 4

In this example, the above-mentioned deep purification device is used to treat typical coal chemical concentrated salt wastewater, that is, after being treated by the organic separation unit, it is treated by the nanofiltration of the first-level salt separation unit and crystallization treatment by the second-level salt separation device, and the COD before and after treatment is investigated. Removal rate (referring to the COD removal rate of COD in the brine pool compared with the COD of raw water), the total recovery rate of salt.

In this embodiment, the organic separation device uses a roll-type microfiltration membrane with a membrane pore size of 0.1 μm; the first-stage salt separation device uses a nanofiltration membrane with a water inlet pressure of 6.5 MPa.

The inflow of concentrated salt wastewater from a certain coal chemical industry is 40m ³ /h, the salt content is 5.1%wt, and the main salts are sodium sulfate and sodium chloride; raw water: sulfate radical 8250mg/L, chloride radical 23850mg/L, COD 979mg /L, total hardness 10mg/L, soluble silicon 20mg/L.

The concentrated brine enters the organic separation unit after pretreatment to remove total hardness and soluble silicon. Dosage: TY-120 powdered carbon 750mg/L, polyiron PFS-250mg/L, through coagulation + adsorption + microfiltration membrane filtration After treatment, it is pressurized and enters the primary salt separation unit.

After being treated by the first-stage salt separation device, the salt-to-nitrate ratio (calculated as Cl ^- /SO ₄ ^2- mass ratio) of the produced water is 66, and the interception rate of sulfate radical is 96%; the main salt in the produced brine is sodium chloride , the salt content is 4%, the COD is 433mg/L, the COD rejection rate is about 55%, and the total salt recovery rate is about 97%.

Analysis of the organic components in the sludge produced by the roll-type microfiltration membrane and the mother liquor of the secondary salt separation device found that the organic separation unit composed of the combination agent of the present invention + roll-type microfiltration membrane has a significant adsorption and removal effect on organic matter with a molecular weight of <1000Da , while the one-stage nanofiltration salt separation unit has a significant interception effect on organic matter with a molecular weight > 1000Da; in addition, the organic separation unit has a significant removal effect on hydrophobic neutral organic matter, hydrophilic organic matter and hydrophobic basic organic matter, while the first-stage The nanofiltration salt separation unit mainly has a remarkable interception effect on hydrophobic acidic organic substances. The two just complement each other in terms of the molecular weight level of organic matter removal and the properties of organic matter. The nanofiltration device of the organic separation unit and the first-stage salt separation unit can better cooperate to remove organic matter in wastewater.

Part of the hydrophobic and acidic organic matter passes through the organic separation unit, is intercepted by the nanofiltration salt separation unit, and enters the freeze crystallization device of the secondary salt separation unit with the divalent salt liquid flow, and remains in the mother liquor after freeze crystallization , and Glauber's salt is precipitated in the form of crystals, so as to be separated from this part of organic matter, and the produced Glauber's salt can then be used to produce high-purity sodium sulfate.

The relevant parameters of the above embodiments are shown in Table 1:

Table 1

It can be seen from Table 1 that:

Based on the results of the two experiments A and B in Example 1, it can be seen that the combined agent composed of TY-120 and polyferric PFS has a higher COD removal rate than the combined agent composed of MZ-800 and polyferric PFS;

Based on the experimental results of item C in Example 1 and Comparative Example 1, it can be seen that adding TY-120 powdered carbon and polyferron combination agent has a higher COD removal rate than adding TY-120 powdered carbon alone;

Based on the experimental results of A and C items in Example 1 and A item in Comparative Example 2, it can be seen that adding TY-120 powdered carbon and polyferron combined agent has a higher COD removal rate than adding polyiron alone;

Based on the experimental results of A and B in Comparative Example 2, it can be seen that adding polyferric coagulant alone can obtain a better COD removal rate; not obvious;

Based on the experimental results of Examples 1-3 and Comparative Example 2, it can be seen that although the addition of polyaluminum iron silicate alone has no obvious effect on COD removal, it is compounded with polyiron in a certain proportion and then mixed with TY-120 powdered carbon , can greatly improve the COD removal rate;

Based on the experimental results of Example 4 and Examples 1-3, it can be seen that the removal rate of COD in the obtained brine can reach 55% after being treated by the organic separation unit and then separated by nanofiltration.

Further, the effect of the dosage of different adsorbent TY-120 powdered carbon and coagulant polyiron PFS on the COD removal effect was investigated. The influent COD was 1061.4mg/L, and the results are listed in Table 2. Iron PFS achieves a good COD removal rate within a large dosage range, especially when the weight ratio of adsorbent to coagulant is greater than 3:1, the COD removal rate can reach more than 30%.

Table 2

The above is only an example of the preferred embodiments of the present invention, and is not a limitation to all feasible embodiments of the present invention. Those skilled in the art can make simple replacements, changes, etc. without departing from the core concept taught by the present invention. The implementation mode obtained by means cannot deviate from the coverage scope of the present invention; the actual protection scope of the present invention shall be defined by the claims.

Claims

A deep purification device for concentrated brine, characterized in that: it includes an organic separation unit, the organic separation unit adopts a roll-type microfiltration membrane, and its membrane pore size is ≤0.3 μm; it is combined with a combined agent composed of an adsorbent and a coagulant; The combined medicament is added into the concentrated brine at the upstream side of the roll-type microfiltration membrane, and fully mixed and reacted with the concentrated brine.
The concentrated brine advanced purification device according to claim 1, characterized in that: the adsorbent is activated carbon and/or activated coke, and the coagulant is polyaluminum ferric silicate, polyferric chloride, polyferric sulfate, One or more of polyaluminum chloride, polyaluminum sulfate, and ferrous sulfate.
The deep purification device for concentrated brine according to claim 2, wherein the coagulant includes polyferric sulfate.
The deep purification device for concentrated brine according to claim 2, wherein the coagulant is a mixture of polyferric sulfate and polyaluminum iron silicate, and the mass ratio of the two is ≥1.
The concentrated brine advanced purification device according to any one of claims 1-4, further comprising a primary salt separation unit and a secondary salt separation unit.
The deep purification device for concentrated brine according to claim 5, characterized in that: the first-stage salt separation unit includes a nanofiltration membrane and a high-pressure pump, and the high-pressure pump can provide the inlet water of ≥4.1Mpa to the nanofiltration membrane pressure; the secondary salt separation unit includes a crystallization device.
The device for deep purification of concentrated brine according to claim 6, characterized in that: the material of the nanofiltration membrane is selected from one or a combination of polyamides, polysulfones, and cellulose acetates. Retention rate ≥ 96%.
The concentrated brine advanced purification device according to claim 5, characterized in that: the upstream of the organic separation unit further includes a pretreatment unit, and the pretreatment unit is used to remove the total hardness and soluble silicon of the concentrated brine.
A method for purifying concentrated brine using the purifying device described in any one of claims 1-8, comprising the steps of:

S1. Transport the concentrated salt wastewater to be treated to the original water tank;

S2. Transport the waste water in the raw water tank to the organic separation unit, add the combined agent composed of adsorbent and coagulant to the waste water, mix and react, and then filter through the roll-type microfiltration membrane.
The method for purifying concentrated brine as claimed in claim 9, further comprising the steps of:

S3. After being treated by the organic separation unit, the produced water and sludge are transported to the primary salt separation unit and sludge dehydration device respectively;

S4. After being treated by the primary salt separation unit, the produced water and concentrated water are sent to the brine tank and the secondary salt separation unit respectively;

S5. After being treated by the secondary salt separation device, the generated Glauber's salt is transported to the Glauber's salt pool, and the mother liquor is transported to the raw water tank.
The method according to claim 10, characterized in that: the crystallization temperature of the secondary salt separation unit is between -15°C and 5°C.