A purification system and method for fluorine-containing wastewater

Abstract

The present invention discloses a purification treatment system and method for fluorine-containing wastewater. The purification system comprises a fluorine-containing wastewater storage tank, a bipolar membrane electrodialysis device, an acid storage tank, a first mixer, a first mixing storage tank, a first adsorption column, an alkali storage tank, a second mixer, a second mixing storage tank, a second adsorption column and a pure water storage tank. During purification, power is first applied to perform bipolar membrane electrodialysis treatment to obtain an acid solution and an alkali solution. After the reaction is performed until the concentrations of the acid and alkali solutions reach a predetermined concentration, the acid solution is extracted as needed into the acid storage tank, and the acid solution is mixed with the fluorine-containing wastewater through the first mixer. A mixing reaction is carried out to obtain acidified fluorine-containing wastewater; the acidified fluorine-containing wastewater enters the first mixing liquid storage tank and undergoes deep defluorination in the first adsorption column; the alkali solution is extracted as needed into the alkali liquid storage tank, and mixed with the defluorinated wastewater through the second mixer to obtain purified water; the purified water after the reaction is extracted as needed into the second adsorption column to remove hardness, and the excess purified water is directly discharged. The pure water obtained by the second adsorption column is circulated and distributed to the acid chamber, salt chamber and alkali chamber as required to maintain the volume balance in the acid chamber, salt chamber and alkali chamber. The deep purification method of fluorine-containing wastewater of the present invention can be combined with bipolar membrane electrodialysis on the basis of purifying fluorine-containing wastewater based on nano-adsorption, which can not only realize the deep defluorination process without the addition of external acid and alkali reagents, effectively reducing the treatment cost of defluorination per ton of water, but also forming a circulating reaction system and enhancing the stability of the purification system.

Description

Technical Field

[0001] The present invention belongs to the field of fluorine-containing wastewater treatment, and in particular relates to a system and method for deep purification of fluorine-containing wastewater. Background Art

[0002] Fluoride is an essential trace element for the human body to maintain normal physiological activities. It plays a vital role in promoting growth and development, as well as bone metabolism. While moderate fluoride intake is beneficial to health, excessive intake may lead to fluorosis. Long-term, high-dose fluoride intake can lead to dental fluorosis and skeletal fluorosis; it can even affect various signaling pathways at the cellular level, disrupting the dynamic balance of bone turnover and metabolism. Excessive fluoride intake can also lead to congestive heart failure, hypertension, atherosclerosis, and tendon and ligament ossification.

[0003] Fluoride removal from drinking water is one of the feasible ways to solve the problem of excessive fluoride content in existing drinking water. Researchers have conducted extensive research on technologies for fluoride removal from drinking water, mainly including precipitation, reverse osmosis, electrodialysis, ion exchange, membrane separation, adsorption, etc. A comparative analysis of several current technologies is shown in Table 1.

[0004] Table 1

[0005]

[0006]

[0007] It can be seen from the table that traditional drinking water defluoridation technologies all have certain defects. The sedimentation method has slow sedimentation, unstable effluent water quality, the presence of sludge by-products, and the easy generation of secondary pollutants. Although the ion exchange method has a good defluoridation effect, it has potential health risks, and the resin is easily contaminated and oxidized. The regeneration process will produce a large amount of fluoride-containing waste, the regeneration capacity is poor, and the technical cost is high. Although the activated alumina adsorption method and the biomass adsorption method have good defluoridation effects, they ultimately have certain limitations due to the nature of the material itself.

[0008] The currently popular reverse osmosis method has a high desalination rate and can effectively remove dissolved salts, colloids, microorganisms, organic matter, etc. in sewage, and the fluoride concentration is also reduced to a low level. However, due to the high power consumption during the operation of the reverse osmosis device, the cost of treating a ton of water is high. Although this technology can remove fluoride from fluoride-containing wastewater, it also removes potassium, calcium, sodium, magnesium, iron, zinc and other trace elements essential to the human body. Long-term use of reverse osmosis purified water as drinking water also poses health risks to residents. In addition, the treatment of the large amount of membrane concentrate produced daily is also a difficult problem that needs to be solved.

[0009] Therefore, new water treatment technologies are urgently needed for fluoride-containing wastewater. Summary of the Invention

[0010] Purpose of the invention: The present invention aims to provide a new type of deep purification system and method for fluorine-containing wastewater. This method can realize a deep defluorination process without adding external acid and alkali reagents based on nano-composite materials, effectively reducing the treatment cost of defluorination per ton of water.

[0011] Technical solution: The deep purification treatment system for fluorine-containing wastewater of the present invention comprises:

[0012] Fluorine-containing wastewater storage tank, used to store fluorine-containing wastewater to be purified;

[0013] The bipolar membrane electrodialysis device is composed of a bipolar membrane stack, an acid chamber, an alkaline chamber, a salt chamber and an electrolyte chamber, which respectively provide acid solution and alkaline solution for the purification of fluoride-containing wastewater;

[0014] An acid storage tank, the liquid inlet of which is connected to the acid chamber through a pipeline, providing acid solution for the purification of fluorine-containing wastewater;

[0015] The first mixer is connected to the liquid outlets of the fluorine-containing wastewater storage tank and the acid storage tank through pipelines to perform mixing reaction;

[0016] a first mixing liquid storage tank, connected to the first mixer, for collecting wastewater after the mixing reaction;

[0017] A first adsorption column is filled with a nanocomposite material and is connected to a first mixed liquid storage tank via a pipeline to perform deep defluorination on the wastewater;

[0018] Alkali liquid storage tank, whose liquid inlet is connected to the alkali chamber through a pipeline, providing alkaline solution for the purification of fluorine-containing wastewater;

[0019] The second mixer is connected to the first adsorption column and the liquid outlet of the alkali liquid storage tank through pipelines to perform a mixing reaction;

[0020] A second mixing liquid storage tank is connected to the second mixer to collect the purified water after the mixing reaction, and a drain outlet is provided on the second mixing liquid storage tank;

[0021] a second adsorption column filled with aminophosphoric acid chelating resin to remove hardness from a portion of the purified water in the second mixed liquid storage tank;

[0022] The pure water storage tank has a liquid inlet connected to the liquid outlet of the second adsorption column through a pipeline, and its liquid outlet is circulated to the acid chamber, salt chamber and alkali chamber through pipelines to maintain the volume balance in the acid chamber, salt chamber and alkali chamber.

[0023] Furthermore, the acid chamber, alkali chamber and salt chamber of the system are connected to the bipolar membrane stack through the liquid inlet pipe and the liquid outlet pipe to form a circulation reaction.

[0024] The present invention provides a purification method based on the above purification system, comprising the following steps:

[0025] (1) ultrapure water, ultrapure water, salt solution and sodium sulfate solution are respectively loaded into the acid chamber, the alkali chamber, the salt chamber and the electrolyte chamber, and the nanocomposite material and aminophosphoric acid chelating resin are filled into the adsorption column;

[0026] (2) applying power to perform bipolar membrane electrodialysis to obtain an acid solution and an alkaline solution;

[0027] (3) After the acid and alkali solution concentrations reach a predetermined concentration, the acid solution is extracted into an acid storage tank as needed, and mixed with the fluorine-containing wastewater through a first mixer to obtain acidified fluorine-containing wastewater;

[0028] (4) The acidified fluorine-containing wastewater enters the first mixed liquid storage tank and undergoes deep fluorine removal in the first adsorption column;

[0029] (5) extracting the alkaline solution into the alkaline liquid storage tank as needed, mixing it with the defluorinated wastewater through a second mixer to obtain purified water;

[0030] (6) The purified water after the reaction is extracted to the second adsorption column as needed to remove the hardness, and the excess purified water is directly discharged. The pure water obtained by the second adsorption column is circulated and distributed to the acid chamber, salt chamber and alkali chamber as required to maintain the volume balance in the acid chamber, salt chamber and alkali chamber.

[0031] Furthermore, the purification method of the present invention further comprises the steps of:

[0032] (7) When the fluorine concentration of the effluent in step (5) reaches the breakthrough point, the water intake is stopped, and the nanocomposite material and the amino phosphate chelating resin are regenerated, transformed, and rinsed;

[0033] (8) After the two materials are regenerated and transformed in step (7), the regenerated liquids of the two materials are mixed and discharged, and washed with de-hardening water until the water out of the adsorption column is neutral, and then re-introduced into water and enter step (4).

[0034] Furthermore, in step (1) of the purification method of the present invention, the salt solution is a sodium chloride solution with a concentration of 1 to 3 mol / L; and the mass fraction of the sodium sulfate solution is 2 to 5%.

[0035] Furthermore, in step (3) of the purification method of the present invention, the acid solution is a hydrochloric acid solution with a concentration of 0.4 to 3.0 mol / L; the alkaline solution is a sodium hydroxide solution with a concentration of 0.4 to 3.0 mol / L.

[0036] Furthermore, in step (3) of the purification method of the present invention, the pH of the acidified fluorine-containing wastewater is 2.5 to 3.5.

[0037] Furthermore, in step (4) of the purification method of the present invention, the outlet flow rate of the first adsorption column is 8 to 20 BV / h.

[0038] Furthermore, in step (5) of the purification method of the present invention, the pH of the discharged water is 6-10.

[0039] Beneficial effects: Compared with the existing technology, the significant advantages of the present invention are: the deep purification treatment system for fluorine-containing wastewater can be combined with bipolar membrane electrodialysis on the basis of purifying fluorine-containing wastewater based on nano-adsorption, which can not only realize the deep defluorination process without the addition of external acid and alkali reagents, effectively reducing the treatment cost of defluorination per ton of water, but also form a circulating reaction system at the same time, enhancing the stability and efficiency of the purification system. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of the purification treatment system of the present invention. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0042] It should be noted that the nanocomposite material used in the present invention is an anion resin-supported nanozirconia composite material, obtained from the technical solution in the patent application entitled "Industrial Preparation Method of Anion Resin-supported Nanozirconia Composite Material" with prior art publication number CN110694584B. In the purification step (7) of the present invention, water intake is stopped when the fluorine concentration of the effluent reaches the breakthrough point, which is the mass concentration of fluorine in the effluent greater than 1 mg / L.

[0043] like Figure 1As shown, the deep purification treatment system of fluorine-containing wastewater of the present invention comprises a fluorine-containing wastewater storage tank 1 for storing fluorine-containing wastewater to be purified, and a liquid outlet is provided at the bottom end of the fluorine-containing wastewater storage tank 1; a bipolar membrane electrodialysis device 2 for providing an acid solution and an alkaline solution respectively for the purification reaction of the fluorine-containing wastewater, and the bipolar membrane electrodialysis device 2 is composed of a bipolar membrane stack, an acid chamber, an alkaline chamber, a salt chamber and an electrolyte chamber, and the acid chamber, the alkaline chamber and the salt chamber are respectively connected to the bipolar membrane stack through a liquid inlet pipe and a liquid outlet pipe to form a circulation reaction; through the pipe an acid storage tank 3 connected to the acid chamber; a first mixer 4, the first mixer 4 is connected to the liquid outlet of the acid storage tank 3 and the liquid outlet of the fluorine-containing wastewater storage tank 1 through a pipeline, so as to mix the two phases for reaction, and the flow rate of the acid solution can be limited by a flow meter according to actual needs; a first mixing storage tank 5 connected to the first mixer 4 through a pipeline, through which the wastewater after the acidification reaction in the first mixer 4 is collected and the wastewater is mixed and mixed through the first mixing storage tank 5 The first adsorption column 6 is connected to the first adsorption column 6 for deep defluorination purification, and the first adsorption column 6 is filled with nano-composite materials to adsorb and remove fluorine; the liquid outlet of the first adsorption column 6 is connected to the second mixer 8 through a pipeline, and the second mixer 8 is also connected to the alkali liquid storage tank 7, so as to carry out a mixing reaction on the defluorinated wastewater, and the liquid inlet of the alkali liquid storage tank 7 is connected to the alkali chamber to provide alkali solution for the neutralization reaction; the purified water after the neutralization reaction is collected in the second mixing liquid storage tank 9 connected to the second mixer 8, and the second mixing liquid storage tank 9 is provided with a drain port, which can directly discharge the purified water, and the purified water in the second mixer 8 is extracted into the second adsorption column 10 connected thereto according to actual needs, and the second adsorption column 10 is filled with aminophosphoric acid chelating resin to remove the hardness of the purified water; and finally, the pure water obtained by adsorption in the second adsorption column 10 is collected into the pure water liquid storage tank 11 connected thereto, and distributed and circulated to the acid chamber, salt chamber and alkali chamber according to demand to maintain the volume balance in the acid chamber, salt chamber and alkali chamber.

[0044] In addition to the necessary components mentioned above, the purification system can be equipped with corresponding pumps, such as peristaltic pumps, on the connected pipes to ensure smooth purification of the system.

[0045] The present invention is based on the purification method adopted by the above purification system and includes the following steps:

[0046] (1) ultrapure water, ultrapure water, a sodium chloride solution with a concentration of 1 to 3 mol / L, and a sodium sulfate solution with a mass fraction of 2 to 5% are respectively placed in the acid chamber, the alkali chamber, the salt chamber, and the electrolyte chamber, and the nanocomposite material and the aminophosphoric acid chelating resin are filled into the adsorption column;

[0047] (2) applying power to perform bipolar membrane electrodialysis to obtain a hydrochloric acid solution and a sodium hydroxide solution;

[0048] (3) When the concentration of hydrochloric acid is 0.4-3.0 mol / L and the concentration of sodium hydroxide is 0.4-3.0 mol / L, the acid solution is extracted into an acid storage tank as needed, and mixed with the fluorine-containing wastewater through a first mixer to obtain acidified fluorine-containing wastewater with a pH of 2.5-3.5;

[0049] (4) The acidified fluorine-containing wastewater enters the first mixed liquid storage tank and undergoes deep fluorine removal in the first adsorption column. The outlet flow rate of the first adsorption column is 8 to 20 BV / h.

[0050] (5) extracting the alkaline solution into the alkaline liquid storage tank as needed, mixing it with the defluorinated wastewater through a second mixer to obtain purified water with a pH of 6 to 10;

[0051] (6) Extracting the purified water after the reaction to the second adsorption column as needed to remove the hardness. The excess purified water can be directly discharged for use. The pure water obtained by the second adsorption column is circulated and distributed to the acid chamber, salt chamber and alkali chamber as required to maintain the volume balance in the acid chamber, salt chamber and alkali chamber;

[0052] (7) When the fluorine concentration of the purified water in step (5) reaches the breakthrough point, the water intake is stopped, and the nanocomposite material and the amino phosphate chelating resin are regenerated, transformed, and rinsed;

[0053] (8) After the two materials are regenerated and transformed in step (7), the regenerated liquids of the two materials are mixed and discharged, and washed with pure water to remove hardness until the water out of the adsorption column is neutral, and then re-introduced into water and enter step (4).

[0054] Example 1

[0055] This embodiment 1 is used to purify groundwater in a rural area of ​​Taiyuan, Shanxi Province. The water quality before purification is shown in the following table. The above method is used to treat the groundwater in this area.

[0056] Table 1 Water quality component content

[0057] index Concentration before purification (mg / L) Concentration after purification (mg / L) <![CDATA[F - ]]> 1.84 <1 Si 9.73 9.45 <![CDATA[Cl - ]]> 313 321 <![CDATA[NO3 - ]]> 22 22 <![CDATA[SO4 2- ]]> 718 725 <![CDATA[CO3 2- ]]> 106 42 B 0.84 0.81 <![CDATA[K + ]]> 32 29 <![CDATA[Ca 2+ ]]> 269 259 <![CDATA[Na + ]]> 199 213 <![CDATA[Mg 2+ ]]> 74 67 TOC 1.56 1.44

[0058] The purification method of this embodiment 1 specifically comprises the following steps:

[0059] (1) Ten pairs of bipolar membranes were loaded into a bipolar membrane stack, and 5 L of ultrapure water, ultrapure water, 2 mol / L sodium chloride solution, and 5% wt sodium sulfate solution were respectively loaded into the acid chamber, alkali chamber, salt chamber, and electrolyte chamber of the bipolar membrane electrodialysis, and 10 L of nanocomposite material and 10 L of aminophosphoric acid chelating resin were filled into the adsorption column;

[0060] (2) applying power to perform bipolar membrane electrodialysis to obtain a hydrochloric acid solution and a sodium hydroxide solution, with a constant current of 1.5 A;

[0061] (3) After a period of reaction, when the concentrations of hydrochloric acid and sodium hydroxide reach 0.6 mol / L and 0.6 mol / L respectively, the hydrochloric acid solution is pumped out from the bipolar membrane electrodialysis acid chamber, mixed with the fluorine-containing wastewater, and then discharged;

[0062] (4) The acidified fluorine-containing wastewater enters the first adsorption column filled with nanocomposite materials for deep fluoride removal;

[0063] (5) Pumping out the sodium hydroxide solution and mixing it with the effluent after deep defluoridation and then discharging it;

[0064] (6) pumping part of the discharged neutral effluent into a second adsorption column filled with amino phosphate chelating resin to remove hardness;

[0065] (7) The de-hardened effluent is pumped into a pure water storage tank and then passed into the bipolar membrane electrodialysis acid chamber, alkali chamber, and salt chamber respectively;

[0066] (8) When the fluorine concentration of the effluent in step (5) reaches 1 mg / L, the water intake is stopped, and the nanocomposite material and the amino phosphate chelating resin are regenerated and transformed; a mixed solution of NaCl and NaOH with a mass fraction of 3% and a NaCl solution are used to desorb, regenerate and transform the nanocomposite material at a flow rate of 15 BV / h, and HCl and NaOH solutions are used to regenerate and transform the amino chelating resin respectively at a flow rate of 15 BV / h.

[0067] (9) After the two materials are regenerated and transformed in step (8), the regenerated liquids of the two materials are mixed and discharged, and washed with de-hardening water until the water outlet of the adsorption column is neutral at a flow rate of 15 BV / h. Then, water is re-introduced and the process proceeds to step (4).

[0068] Example 2

[0069] This Example 2 is used to purify groundwater in a rural area of ​​Yulin, Shaanxi Province. The water quality before purification is shown in the following table. The above method is used to treat the groundwater in this area.

[0070] Table 2 Water quality component content

[0071] index Concentration before purification (mg / L) Concentration after purification (mg / L) <![CDATA[F - ]]> 3.51 <1 Si 6.53 6.32 <![CDATA[Cl - ]]> 227 239 <![CDATA[NO3 - ]]> 27 31 <![CDATA[SO4 2- ]]> 563 580 <![CDATA[CO3 2- ]]> 92 43 B 0.23 0.19 <![CDATA[K + ]]> 57 62 <![CDATA[Ca 2+ ]]> 109 77 <![CDATA[Na + ]]> 354 340 <![CDATA[Mg 2+ ]]> 23 28 TOC 1.42 1.34

[0072] The purification method of this embodiment 2 specifically includes the following steps:

[0073] (1) Ten pairs of bipolar membranes were loaded into a bipolar membrane stack, and 10 L of ultrapure water, ultrapure water, 1.8 mol / L sodium chloride solution, and 2% wt sodium sulfate solution were respectively loaded into the acid chamber, alkali chamber, salt chamber, and electrolyte chamber of the bipolar membrane electrodialysis, and 30 L of nanocomposite material and 30 L of aminophosphoric acid chelating resin were filled into the adsorption column;

[0074] (2) applying power to perform bipolar membrane electrodialysis to obtain a hydrochloric acid solution and a sodium hydroxide solution, with a constant current of 1.8 A;

[0075] (3) After a period of reaction, when the concentrations of hydrochloric acid and sodium hydroxide reach 1.1 mol / L and 1.1 mol / L, respectively, the hydrochloric acid solution is pumped out from the bipolar membrane electrodialysis acid chamber, mixed with the fluorine-containing wastewater, and then discharged;

[0076] (4) The acidified fluorine-containing wastewater enters the first adsorption column filled with nanocomposite materials for deep fluoride removal;

[0077] (5) Pumping the sodium hydroxide solution out of the alkali tank and mixing it with the effluent after deep defluoridation and then discharging it;

[0078] (6) pumping part of the discharged neutral effluent into a second adsorption column filled with amino phosphate chelating resin to remove hardness;

[0079] (7) The de-hardened effluent is pumped into a pure water storage tank and then passed into the bipolar membrane electrodialysis acid chamber, alkali chamber, and salt chamber respectively;

[0080] (8) When the fluorine concentration of the effluent in step (5) reaches 1 mg / L, the water intake is stopped, and the nanocomposite material and the amino phosphate chelating resin are regenerated and transformed; a mixed solution of NaCl and NaOH with a mass fraction of 5% and a NaCl solution are used to desorb, regenerate and transform the nanocomposite material at a flow rate of 10 BV / h, and HCl and NaOH solutions are used to regenerate and transform the amino chelating resin respectively at a flow rate of 10 BV / h.

[0081] (9) After the two materials are regenerated and transformed in step (8), the regenerated liquids of the two materials are mixed and discharged, and then washed with de-hardening water until the water outlet of the adsorption column is neutral at a flow rate of 10 BV / h. Then, water is re-introduced and the process proceeds to step (4).

[0082] Example 3

[0083] This Example 3 is used to purify groundwater in a rural area of ​​Datong, Shanxi Province. The water quality before purification is shown in the following table. The above method is used to treat the groundwater in this area.

[0084] Table 3 Water quality component content

[0085]

[0086]

[0087] The purification method of this embodiment 3 specifically includes the following steps:

[0088] (1) 20 pairs of bipolar membranes were loaded into a bipolar membrane stack, and 25 L of ultrapure water, ultrapure water, 1.5 mol / L sodium chloride solution, and 4% wt sodium sulfate solution were respectively loaded into the acid chamber, alkali chamber, salt chamber, and electrolyte chamber of the bipolar membrane electrodialysis, and 50 L of nanocomposite material and 50 L of aminophosphoric acid chelating resin were filled into the adsorption column;

[0089] (2) applying power to perform bipolar membrane electrodialysis to obtain a hydrochloric acid solution and a sodium hydroxide solution, with a constant current of 2.0 A;

[0090] (3) After a period of reaction, when the concentrations of hydrochloric acid and sodium hydroxide reach 1.3 mol / L and 1.3 mol / L respectively, the hydrochloric acid solution is pumped out from the bipolar membrane electrodialysis acid chamber, mixed with the fluorine-containing wastewater, and then discharged;

[0091] (4) The acidified fluorine-containing wastewater enters the first adsorption column filled with nanocomposite materials for deep fluoride removal;

[0092] (5) Pumping the sodium hydroxide solution out of the alkali tank and mixing it with the effluent after deep defluoridation and then discharging it;

[0093] (6) pumping part of the discharged neutral effluent into a second adsorption column filled with amino phosphate chelating resin to remove hardness;

[0094] (7) The de-hardened water is pumped into the pure water tank and then passed into the bipolar membrane electrodialysis acid chamber, alkali chamber and salt chamber respectively;

[0095] (8) When the fluorine concentration of the effluent in step (5) reaches 1 mg / L, the water intake is stopped, and the nanocomposite material and the amino phosphate chelating resin are regenerated and transformed; a mixed solution of NaCl and NaOH with a mass fraction of 8% and a NaCl solution are used to desorb, regenerate and transform the nanocomposite material at a flow rate of 5 BV / h, and HCl and NaOH solutions are used to regenerate and transform the amino chelating resin respectively at a flow rate of 5 BV / h.

[0096] (9) After the two materials are regenerated and transformed in step (8), the regenerated liquids of the two materials are mixed and discharged, and washed with de-hardening water until the water outlet of the adsorption column is neutral at a flow rate of 5 BV / h. Then, water is re-introduced and the process proceeds to step (4).

[0097] The results in Tables 1 to 3 of the above examples demonstrate that the method for deep purification of fluorine-containing wastewater of the present invention can efficiently remove fluorine from fluorine-containing wastewater without adding any external chemicals, and is green and pollution-free. The specific results of each stage are shown in Table 4.

[0098] Table 4 Process parameters at each stage

[0099] Example Acidified effluent pH Neutralize effluent pH Running volume (BV) Example 1 2.8～3.0 6.1～8.2 3800 Example 2 2.9～3.6 7.0～9.3 3400 Example 3 3.2～3.8 7.5～9.5 3200

Claims

1. A purification system for fluorine-containing wastewater, characterized in that: The purification system includes: A fluorine-containing wastewater storage tank (1) is used to store the fluorine-containing wastewater to be purified; A bipolar membrane electrodialysis device (2) is composed of a bipolar membrane stack, an acid chamber, an alkali chamber, a salt chamber and an electrolyte chamber, and is used to provide an acid solution and an alkali solution for purifying fluorine-containing wastewater; an acid storage tank (3), the liquid inlet of which is connected to the acid chamber through a pipeline, and provides acid solution for the purification of fluorine-containing wastewater; a first mixer (4) connected to the liquid outlets of the fluorine-containing wastewater storage tank (1) and the acid storage tank (2) through pipelines for performing a mixing reaction; A first mixing liquid storage tank (5) is connected to the first mixer (4) to collect wastewater after the mixing reaction; A first adsorption column (6) is filled with a nanocomposite material and is connected to a first mixed liquid storage tank (5) via a pipeline to remove fluorine from the wastewater; an alkali liquid storage tank (7), the liquid inlet of which is connected to the alkali chamber through a pipeline, and provides alkali solution for the purification of fluorine-containing wastewater; a second mixer (8) connected to the first adsorption column (6) and the liquid outlet of the alkali liquid storage tank (7) through pipelines to perform a mixing reaction; A second mixing liquid storage tank (9) is connected to the second mixer (8) to collect the purified water after the mixing reaction, and a drain outlet is provided on the second mixing liquid storage tank (9); a second adsorption column (10) filled with aminophosphoric acid chelating resin to remove hardness from a portion of the purified water in the second mixed liquid storage tank (9); The pure water storage tank (11) has a liquid inlet connected to the liquid outlet of the second adsorption column (10) through a pipeline, and its liquid outlet is circulated to the acid chamber, salt chamber and alkali chamber through pipelines to maintain the volume balance in the acid chamber, salt chamber and alkali chamber.

2. The deep purification treatment system for fluorine-containing wastewater according to claim 1, characterized in that: The acid chamber, the alkali chamber and the salt chamber are respectively connected to the bipolar membrane stack through the liquid inlet pipe and the liquid outlet pipe to form a circulation reaction.

3. A purification method using the purification system according to claim 1, characterized in that: The steps include: (1) ultrapure water, ultrapure water, salt solution and sodium sulfate solution are respectively loaded into the acid chamber, the alkali chamber, the salt chamber and the electrolyte chamber, and the nanocomposite material and aminophosphoric acid chelating resin are filled into the adsorption column; (2) applying power to perform bipolar membrane electrodialysis to obtain an acid solution and an alkaline solution; (3) After the acid and alkali solution concentrations reach a predetermined concentration, the acid solution is extracted into an acid storage tank as needed, and mixed with the fluorine-containing wastewater through a first mixer to obtain acidified fluorine-containing wastewater; (4) The acidified fluorine-containing wastewater enters the first mixed liquid storage tank and undergoes deep fluorine removal in the first adsorption column; (5) extracting the alkaline solution into the alkaline liquid storage tank as needed, mixing it with the defluorinated wastewater through a second mixer to obtain purified water; (6) The purified water after the reaction is extracted to the second adsorption column as needed to remove the hardness, and the excess purified water is directly discharged. The pure water obtained by the second adsorption column is circulated and distributed to the acid chamber, salt chamber and alkali chamber as required to maintain the volume balance in the acid chamber, salt chamber and alkali chamber.

4. The purification method according to claim 3, characterized in that: The purification method further comprises the following steps: (7) When the fluorine concentration of the effluent in step (5) reaches the breakthrough point, the water intake is stopped, and the nanocomposite material and the amino phosphate chelating resin are regenerated, transformed, and rinsed; (8) After the two materials are regenerated and transformed in step (7), the regenerated liquids of the two materials are mixed and discharged, and washed with de-hardening water until the water out of the adsorption column is neutral, and then re-introduced into water and enter step (4).

5. The purification method according to claim 3 or 4, characterized in that: In step (1), the salt solution is a sodium chloride solution with a concentration of 1 to 3 mol / L; the mass fraction of the sodium sulfate solution is 2 to 5% wt.

6. The purification method according to claim 3 or 4, characterized in that: In step (3), the acid solution is a hydrochloric acid solution with a concentration of 0.4 to 3.0 mol / L; the alkaline solution is a sodium hydroxide solution with a concentration of 0.4 to 3.0 mol / L.

7. The purification method according to claim 3 or 4, characterized in that: In step (3), the pH of the acidified fluorine-containing wastewater is 2.5 to 3.

8.

8. The purification method according to claim 3 or 4, characterized in that: In step (4), the outlet flow rate of the first adsorption column is 8 to 20 BV / h.

9. The purification method according to claim 3 or 4, characterized in that: In step (5), the pH of the purified water is 6 to 10.

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