A saturated tower sewage water recycling system

Abstract

This invention relates to the field of wastewater treatment technology, and more particularly to a saturated tower wastewater recycling and reuse system. The system includes a pretreatment unit for wastewater purification, a directional separation unit for residual methanol recovery, and a desalination and purification unit for desalinated water recovery. The pretreatment unit includes a pretreatment tank, the directional separation unit includes a permeation tank with multiple permeate membrane elements, and the desalination and purification unit includes a purification tank with multiple nanofiltration membrane elements and reverse osmosis membrane elements. This invention employs differentiated separation treatment based on the different characteristics of substances in methanol wastewater. Specifically, it involves multi-impurity pretreatment with simultaneous adsorption of organic impurities and ion exchange for inorganic impurities; directional separation relying on membrane permeation and distillation coupling to recover trace amounts of methanol; and desalination and purification of the desalinated water through gradient membrane filtration and ion exchange. Ultimately, this achieves efficient recovery of water and methanol resources and complete removal of pollutants from the saturated tower wastewater, resulting in highly efficient resource recovery and treatment.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a saturated tower discharge wastewater recovery and reuse system. Background Technology

[0002] In the methanol production process, the saturated tower wastewater is characterized by the coexistence of multiple impurities: it not only contains high concentrations of calcium and magnesium ions and inorganic salts, but also carries trace amounts of methanol with recovery value, as well as organic impurities such as formaldehyde and formic acid that can easily cause environmental pollution and subsequent membrane fouling. Directly discharging this wastewater would result in a double waste of water and methanol resources, failing to meet the requirements of resource recycling; furthermore, the organic impurities and high salinity in the wastewater would damage the aquatic and soil ecosystems, violating environmental discharge regulations.

[0003] However, in common wastewater recycling and desalination processes, the pretreatment technology used only removes suspended solids from the water through simple filtration. It fails to target the removal of organic and inorganic impurities in the wastewater according to their different characteristics. As a result, the pretreated wastewater still carries a large number of impurities into the subsequent separation unit, increasing the load and energy consumption of subsequent treatment. It also easily causes problems such as membrane module fouling and equipment scaling, which seriously affects the overall treatment efficiency and resource recovery effect, thus restricting the efficient recycling of saturated tower discharge wastewater.

[0004] To address the aforementioned technical shortcomings, a solution is proposed that employs differentiated separation and treatment methods based on the different characteristics of substances in methanol wastewater for efficient recovery. This involves multi-substance pretreatment removal, targeted methanol separation, and deep purification with desalinated water to achieve efficient resource recovery. Summary of the Invention

[0005] The purpose of this invention is to provide a saturated tower wastewater recycling and reuse system to solve the aforementioned technical defects.

[0006] The objective of this invention can be achieved through the following technical solution: a saturated tower wastewater recycling system, comprising a pretreatment unit for purifying wastewater, a directional separation unit for recovering residual methanol, and a desalination and purification unit for recovering desalinated water. The pretreatment unit includes a pretreatment tank, the upper and lower layers of which are respectively filled with modified activated carbon oxidized by nitric acid and nano-hydroxyapatite particles. The directional separation unit includes a permeation tank, the interior of which is provided with multiple permeation membrane elements. The desalination and purification unit includes a purification tank, the interior of which is provided with multiple nanofiltration membrane elements, and the interior of each nanofiltration membrane element is provided with a reverse osmosis membrane element.

[0007] Preferably, the pretreatment tank is equipped with an inlet pipe at the top and a stainless steel sieve plate is fixedly installed inside the pretreatment tank. An air flotation tank is provided on one side of the pretreatment tank, and a micro-nano bubble generator is installed on one side of the air flotation tank. A connecting pipe is fixedly connected to the bottom of the pretreatment tank, penetrating into the air outlet pipe of the micro-nano bubble generator, and the free end of the connecting pipe is an inclined tip structure.

[0008] Preferably, a second connecting pipe is fixedly connected between the permeation tank and the flotation tank, a first partition is fixedly connected inside the permeation tank, the permeation membrane is composed of a ceramic support and a polydimethylsiloxane membrane on its surface, the ceramic support is fixedly connected through the top of the first partition, a distillation column is provided on one side of the permeation tank, a three-way pipe is fixedly connected between one side of the permeation tank and the bottom of the distillation column and the purification tank, and a third connecting pipe is fixedly connected to the bottom of the permeation tank.

[0009] Preferably, rotating rollers are rotatably connected to both sides of the flotation tank, and the rotating rollers are connected to each other by a transmission mesh belt. A scraping filter screen is fixedly connected to the surface of the transmission mesh belt by an elastic strip. Multiple scraping filters are provided. A collection hopper is fixedly connected to one side of the flotation tank, and an inclined barrier filter screen is fixedly connected to one side of the flotation tank.

[0010] Preferably, the upper, middle and lower layers of the distillation column are fixedly connected to a porous sieve plate, a distributor and stainless steel corrugated packing respectively, the end of the connecting pipe three passes through the distillation column and connects to the distributor, and the top of the distillation column is fixedly connected to the discharge pipe one.

[0011] Preferably, feed pumps are installed on connecting pipe 2, connecting pipe 3, and the tee pipe, a control valve is installed on the tee pipe at the distillation column, and heaters are installed on both the flotation tank and the distillation column.

[0012] Preferably, a partition plate two is fixedly connected inside the purification tank, and both the nanofiltration membrane core and the reverse osmosis membrane core are fixedly connected between the bottom of the partition plate two and the purification tank. The inner cavity of the reverse osmosis membrane core is connected to the inside of the purification tank above the partition plate two, and a discharge pipe two is fixedly connected to the top of the purification tank.

[0013] Preferably, the upper part of the second partition is provided with a strong acid cation exchange resin layer, a strong base anion exchange resin layer and a mixed cation and anion resin layer from bottom to top.

[0014] The beneficial effects of this invention are as follows:

[0015] (1) This invention addresses the different characteristics of methanol, salt, and organic impurities in methanol wastewater by employing differentiated separation and treatment methods for efficient recovery. Through the synergistic effect of multiple steps, such as pretreatment by modified activated carbon adsorption and nano-hydroxyapatite ion exchange, directional concentration by membrane permeation and distillation column packing mass transfer, and deep desalination by dual-membrane gradient filtration and tertiary ion exchange, the invention achieves directional recovery of methanol resources and regeneration of water resources in saturated tower wastewater. Compared with the limitations of single separation technology in treating multiple impurities incompletely and having low resource recovery rate, this invention can achieve efficient resource recovery and treatment.

[0016] (2) The present invention uses the structure of micro-nano bubble generator, elastic strip, scraper filter and collection hopper in the air flotation tank to efficiently capture small colloidal particles, avoid impurities from being suspended and deposited, and link the scraper filter to make the transmission belt rotate, automatically remove scum without residue, prevent the tank blockage caused by untimely scum removal, and block the filter screen to intercept the unfloated impurities, thereby reducing the pollutants entering the subsequent system from the source, so as to achieve efficient capture, automatic continuous removal and secondary interception of impurities, and solve the problem of air flotation impurity residue causing blockage of subsequent membrane modules. Attached Figure Description

[0017] The invention will now be further described with reference to the accompanying drawings;

[0018] Figure 1 This is a schematic diagram of the structure of the present invention;

[0019] Figure 2 This is a schematic diagram of the pretreatment tank of the present invention;

[0020] Figure 3 This is a schematic diagram of the structure of the air flotation tank of the present invention;

[0021] Figure 4 This is a schematic diagram of the permeation tank of the present invention;

[0022] Figure 5 This is a schematic diagram of the distillation column of the present invention;

[0023] Figure 6 This is a schematic diagram of the purification tank of the present invention.

[0024] Legend:

[0025] 11. Pretreatment tank; 12. Flotation tank; 13. Micro-nano bubble generator; 14. Connecting pipe 1; 15. Rotating roller; 16. Transmission mesh belt; 17. Elastic strip; 18. Scraper screen; 19. Scraper hopper; 110. Barrier screen;

[0026] 21. Permeate tank; 22. Permeate membrane components; 23. Connecting pipe two; 24. Distillation column; 25. T-joint; 26. Connecting pipe three; 27. Porous sieve plate; 28. Distributor; 29. ​​Stainless steel corrugated packing;

[0027] 31. Purification tank; 32. Nanofiltration membrane core; 33. Reverse osmosis membrane core. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: Please refer to Figures 1-6 As shown, the problem that the different characteristics of organic and inorganic impurities in wastewater cannot be targeted for removal, resulting in the pretreated wastewater still carrying a large number of impurities into the subsequent separation unit, affecting the overall treatment efficiency and resource recovery effect, can be solved by the following solutions;

[0030] This embodiment of a saturated tower wastewater recycling and reuse system includes a pretreatment unit for purifying wastewater, a directional separation unit for recovering residual methanol, and a desalination and purification unit for recovering desalinated water. The pretreatment unit includes a pretreatment tank 11, and the upper and lower layers of the pretreatment tank 11 are respectively filled with modified activated carbon and nano-hydroxyapatite particles that have been oxidized by nitric acid.

[0031] The wastewater from the saturated tower used in methanol production flows from the pretreatment tank 11 and first comes into contact with nitric acid-oxidized modified granular activated carbon. The modified activated carbon is rich in polar groups such as carboxyl and hydroxyl groups on its surface. Organic pollutant molecules such as methanol and formaldehyde in the water are adsorbed into the pores of the activated carbon by forming hydrogen bonds with the polar groups on the surface of the activated carbon. The porous structure of the activated carbon provides an adsorption area to capture organic pollutants in the water and remove organic impurities in a targeted manner.

[0032] When wastewater flows through nano-hydroxyapatite particles, calcium and phosphate ions in the nano-hydroxyapatite lattice will undergo ion exchange with magnesium and calcium ions in the wastewater. The magnesium and calcium ions in the wastewater enter the hydroxyapatite lattice, while the calcium ions in the lattice are released into the water, removing hardness ions from the wastewater, thereby achieving the initial removal of suspended solids, organic and inorganic impurities and other substances.

[0033] The directional separation unit includes a permeation tank 21, which is equipped with multiple permeation membrane elements 22 to adsorb and dissolve methanol molecules in wastewater. The desalination and purification unit includes a purification tank 31, which is equipped with multiple nanofiltration membrane elements 32, and each nanofiltration membrane element 32 is equipped with a reverse osmosis membrane element 33. Salt ions are removed by gradient filtration through the nanofiltration membrane element 32 and the reverse osmosis membrane element 33, and the nanofiltration membrane element 32 protects the reverse osmosis membrane element 33 from fouling.

[0034] The pretreatment tank 11 is equipped with an inlet pipe at the top and a stainless steel sieve plate is fixedly installed inside the pretreatment tank 11 to prevent the two media, modified activated carbon and nano hydroxyapatite particles, from mixing. A flotation tank 12 is set on one side of the pretreatment tank 11, and a micro-nano bubble generator 13 is installed on one side of the flotation tank 12. The wastewater that has been initially purified is injected into the flotation tank 12 and flows through the area of ​​the micro-nano bubble generator 13. The jet pump of the micro-nano bubble generator 13 forms a negative pressure by spraying the wastewater at high speed, and draws in air from the outside. The air and wastewater are initially mixed in the jet pump to form a gas-liquid mixture, breaking the large bubbles in the air into tiny bubbles.

[0035] A quantitative amount of cationic polyacrylamide is injected into the flotation tank 12, which dissolves in the water to form positively charged polymer chains and adsorbs onto the surface of negatively charged suspended solids and colloidal particles. At the same time, microbubbles combine with pollutants through charge adsorption to form a composite floc of microbubbles, reagents and pollutants, which further adsorbs and removes impurities in the wastewater.

[0036] The bottom of the pretreatment tank 11 is fixedly connected to a connecting pipe 14 that extends into the air outlet pipe of the micro-nano bubble generator 13. The free end of the connecting pipe 14 has an inclined tip structure. The connecting pipe 14 and the air outlet pipe of the micro-nano bubble generator 13 form a Venturi structure, which is used to assist in the extraction of sewage in the pretreatment tank 11 and improve the pretreatment efficiency.

[0037] A connecting pipe 23 is fixedly connected between the permeation tank 21 and the flotation tank 12. A partition 1 is fixedly connected inside the permeation tank 21. The permeation membrane 22 is composed of a ceramic support and a polydimethylsiloxane membrane on its surface. The ceramic support is fixedly connected to the top of the partition 1 through a through-hole. A distillation column 24 is provided on one side of the permeation tank 21. A three-way pipe 25 is fixedly connected between one side of the permeation tank 21 and the bottom of the distillation column 24 and the purification tank 31. A connecting pipe 3 26 is fixedly connected to the bottom of the permeation tank 21.

[0038] The clarified liquid obtained from removing suspended solids and colloidal particles in the flotation tank 12 is injected into the permeation tank 21 through connecting pipe 23. Due to the hydrophobic properties of the polydimethylsiloxane membrane and the low polarity of methanol, methanol molecules in the wastewater are preferentially adsorbed and dissolved by the surface membrane. Subsequently, driven by the concentration difference across the membrane, they diffuse through the membrane pores into the ceramic support and are converted into a gaseous state by the temperature of the wastewater, forming methanol vapor. The methanol vapor is injected into the distillation column 24 through connecting pipe 26 for further purification.

[0039] The upper, middle and lower layers of the distillation column 24 are fixedly connected to a perforated sieve plate 27, a distributor 28 and a stainless steel corrugated packing 29, respectively. The end of the connecting pipe 26 passes through the distillation column 24 and connects to the distributor 28. Methanol vapor is evenly distributed by the distributor 28 and contacts the stainless steel corrugated packing 29. Utilizing the difference in boiling points between methanol and water, water is transferred from the vapor to the liquid through the reverse interaction of vapor rising and liquid falling. The top of the distillation column 24 is fixedly connected to the discharge pipe 1.

[0040] Feed pumps are installed on connecting pipe 23, connecting pipe 3 26 and tee pipe 25. A control valve is installed on tee pipe 25 at the distillation column 24. Wastewater in permeation tank 21 is injected into purification tank 31 through tee pipe 25 and the corresponding feed pump. By opening the control valve, excess water inside distillation column 24 is transported through tee pipe 25 for deionization treatment.

[0041] Heaters are installed on both the flotation tank 12 and the distillation column 24 for heating the wastewater in the flotation tank 12 and for secondary evaporation of the wastewater in the distillation column 24. A small amount of deionized water is pre-injected into the bottom of the distillation column 24 and heated by the heater on the distillation column 24. The secondary vapor generated by the liquid at the bottom of the distillation column 24 flows upward and forms a counter-current contact with the liquid returning from the top of the column on the packing layer and the sieve plate, providing mass transfer conditions for the deep separation of methanol and water.

[0042] The purification tank 31 is fixedly connected to a partition plate 2. The nanofiltration membrane core 32 and the reverse osmosis membrane core 33 are both fixedly connected between the bottom of the partition plate 2 and the purification tank 31. The inner cavity of the reverse osmosis membrane core 33 is connected to the interior of the purification tank 31 above the partition plate 2. The wastewater in the permeation tank 21 is injected into the purification tank 31 through the three-way pipe 25 and the corresponding feed pump. The salt ions are removed by gradient filtration through the nanofiltration membrane core 32 and the reverse osmosis membrane core 33. The nanofiltration membrane core 32 protects the reverse osmosis membrane core 33 from contamination. The top of the purification tank 31 is fixedly connected to the discharge pipe 2.

[0043] Above the second partition, from bottom to top, there are layers of strong acid cation exchange resin, strong base anion exchange resin, and a mixed cation and anion resin. The crude desalinated water after double membrane desalination passes through the layers of strong acid cation exchange resin, strong base anion exchange resin, and mixed cation and anion resin in sequence above the second partition.

[0044] The residual metal ions in the water undergo an exchange reaction with specific ions on the strong acid cation exchange resin layer. The resin adsorbs the metal ions and releases hydrogen ions, thereby removing hardness ions from the water.

[0045] After cation exchange, the water enters the strongly basic anion exchange resin layer. The residual anions in the water undergo an exchange reaction with specific ions on the strongly basic anion exchange resin layer. The resin adsorbs anions and releases hydroxide ions. Hydrogen ions combine with hydroxide ions to form water.

[0046] The trace ions remaining in the water continue to exchange with the cation and anion mixed resin layer. At the same time, the irregular arrangement of the cation and anion resin particles forms a multi-stage filtration effect, further adsorbing trace organic matter in the water to achieve efficient removal of trace ions and obtain desalinated water.

[0047] Example 2: Please refer to Figure 1 and Figure 3 As shown, the following solutions can be used to address the problem of residual impurities caused by untimely sludge removal in the flotation tank, which leads to clogging of the subsequent membrane modules.

[0048] In this embodiment, rotating rollers 15 are rotatably connected to both sides of the flotation tank 12, and the rotating rollers 15 are connected to each other by a transmission belt 16. A scraping filter 18 is fixedly connected to the surface of the transmission belt 16 by an elastic strip 17. Multiple scraping filters 18 are provided. The impact force carried by the gas-liquid mixture sprayed inside the flotation tank 12 by the micro-nano bubble generator 13 pushes the scraping filter 18 under the liquid surface to move, thereby causing the transmission belt 16 to rotate. Multiple scraping filters 18 rotate sequentially to the liquid surface, thereby continuously scraping the scum layer floating on the liquid surface to the collection hopper 19 area.

[0049] A collection hopper 19 is fixedly connected to one side of the flotation tank 12. A scraper filter 18 contacts the collection hopper 19 and rotates with the drive belt 16. The elastic strip 17 connecting the scraper filter 18 and the drive belt 16 deforms, causing the scraper filter 18 to deflect relatively and scrape the scum layer on one side into the collection hopper 19 for collection. An inclined barrier filter 110 is fixedly connected to one side of the flotation tank 12. The sewage in the flotation tank 12 passes through the barrier filter 110 to remove suspended solids and colloidal particles, and the resulting clear liquid enters the connecting pipe 23.

[0050] Example 3: Please refer to Figures 1-6 As shown, the present invention also proposes a method for using a saturated tower wastewater recycling system, comprising the following steps:

[0051] Step 1: Wastewater from the saturated tower used in methanol production is injected into pretreatment tank 11 through the inlet pipe. It first contacts the upper layer of granular activated carbon modified by nitric acid oxidation. Because the surface of the modified activated carbon is rich in polar groups such as carboxyl and hydroxyl groups, when the wastewater flows through the gaps between the modified activated carbon particles, the molecules of organic pollutants such as methanol and formaldehyde in the water are adsorbed into the pores of the activated carbon by forming hydrogen bonds with the polar groups on the surface of the activated carbon. The porous structure of the activated carbon provides an adsorption area to capture organic pollutants in the water and remove organic impurities in a targeted manner. Then, the lattice structure of nano-hydroxyapatite is utilized. The calcium ions and phosphate ions in its lattice will undergo ion exchange with the magnesium ions and calcium ions in the wastewater. The magnesium ions and calcium ions in the wastewater enter the lattice of hydroxyapatite, while the calcium ions in the lattice are released into the water, removing hardness ions in the wastewater and initially removing suspended solids, organic and inorganic impurities.

[0052] Step 2: The preliminarily purified wastewater is injected into the flotation tank 12 through connecting pipe 23 and flows through the area of ​​the micro-nano bubble generator 13. The jet pump of the micro-nano bubble generator 13 creates negative pressure by spraying the wastewater at high speed, and draws in air from the outside. The air and wastewater are initially mixed in the jet pump to form a gas-liquid mixture, breaking the large bubbles in the air into tiny bubbles. A certain amount of cationic polyacrylamide is injected into the flotation tank 12, which dissolves in the water to form positively charged polymer chains, which are adsorbed on the surface of negatively charged suspended solids and colloidal particles. At the same time, the microbubbles combine with pollutants through charge adsorption to form a composite floc of microbubbles, reagents and pollutants.

[0053] Step 3: The composite flocs float to the surface of the liquid and form a scum layer through the buoyancy of microbubbles. The impact force of the gas-liquid mixture sprayed by the micro-nano bubble generator 13 inside the flotation tank 12 pushes the scraping filter 18 under the liquid surface to move, which in turn causes the transmission belt 16 to rotate. Multiple scraping filters 18 continuously scrape the scum layer to the collection hopper 19 area. The scraping filters 18 contact the collection hopper 19 and rotate with the transmission belt 16. The elastic strip 17 connecting the two deforms, causing the scraping filters 18 to deflect relatively and scrape the scum layer on one side into the collection hopper 19 for collection.

[0054] Step 4: The clear liquid, after being intercepted and having suspended solids and colloidal particles removed by the barrier filter 110, is drawn into the permeation tank 21 through the connecting pipe 23 and the corresponding feed pump. Due to the hydrophobic properties of the polydimethylsiloxane membrane and the low polarity of methanol, methanol molecules in the wastewater are preferentially adsorbed and dissolved by the surface membrane. Subsequently, driven by the concentration difference across the membrane, they diffuse through the membrane pores into the ceramic support and are converted into gaseous state by the temperature of the wastewater, forming methanol vapor.

[0055] Methanol vapor is drawn into the distillation column 24 through connecting pipe 26 and the corresponding feed pump. Then, the methanol vapor is evenly distributed by the distributor 28 and comes into contact with the stainless steel corrugated packing 29. Taking advantage of the boiling point difference between methanol and water, water is transferred from the vapor to the liquid through the reverse interaction of vapor rising and liquid falling. A small amount of deionized water is pre-injected at the bottom of the distillation column 24 and heated by the heater on the distillation column 24. The secondary vapor generated by the liquid at the bottom of the distillation column 24 flows upward and forms a reverse contact with the liquid returning from the top of the column on the packing layer and the sieve plate, providing mass transfer conditions for the deep separation of methanol and water.

[0056] Step 5: Wastewater in permeate tank 21 is injected into purification tank 31 via three-way pipe 25 and corresponding feed pump. Salt ions are removed by gradient filtration through nanofiltration membrane core 32 and reverse osmosis membrane core 33. Nanofiltration membrane core 32 protects reverse osmosis membrane core 33 from contamination. By opening the control valve, excess water inside distillation column 24 is deionized. The crude desalinated water after double membrane desalination passes through the strong acid cation exchange resin layer, strong base anion exchange resin layer and mixed cation and anion resin layer above the second partition plate to exchange metal ions, completing the efficient removal of trace ions to obtain desalinated water.

[0057] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A saturated tower wastewater recovery and reuse system, comprising a pretreatment unit for wastewater purification, a directional separation unit for residual methanol recovery, and a desalination and purification unit for demineralized water recovery, characterized in that, The pretreatment unit includes a pretreatment tank (11), and the upper and lower layers of the pretreatment tank (11) are respectively filled with modified activated carbon and nano-hydroxyapatite particles modified by nitric acid oxidation. The directional separation unit includes a permeation tank (21), and the permeation tank (21) is provided with multiple permeation membrane elements (22). The desalination and purification unit includes a purification tank (31), and the purification tank (31) is provided with multiple nanofiltration membrane elements (32), and the nanofiltration membrane elements (32) are provided with reverse osmosis membrane elements (33).

2. The saturated tower wastewater recycling system according to claim 1, characterized in that, The pretreatment tank (11) is equipped with an inlet pipe at the top and a stainless steel sieve plate is fixedly installed inside the pretreatment tank (11). An air flotation tank (12) is provided on one side of the pretreatment tank (11) and a micro-nano bubble generator (13) is installed on one side of the air flotation tank (12). A connecting pipe (14) is fixedly connected to the bottom of the pretreatment tank (11) and extends through the air outlet pipe of the micro-nano bubble generator (13). The free end of the connecting pipe (14) is an inclined tip structure.

3. The saturated tower wastewater recycling system according to claim 2, characterized in that, A connecting pipe 23 is fixedly connected between the permeation tank (21) and the flotation tank (12). A partition 1 is fixedly connected inside the permeation tank (21). The permeation membrane (22) is composed of a ceramic support and a polydimethylsiloxane membrane on its surface. The ceramic support is fixedly connected through the top of the partition 1. A distillation column (24) is provided on one side of the permeation tank (21). A three-way pipe (25) is fixedly connected between one side of the permeation tank (21) and the bottom of the distillation column (24) and the purification tank (31). A connecting pipe 3 (26) is fixedly connected to the bottom of the permeation tank (21).

4. The saturated tower wastewater recycling system according to claim 2, characterized in that, Rotating rollers (15) are rotatably connected to both sides of the flotation tank (12), and the rotating rollers (15) are connected to each other by a transmission mesh belt (16). A scraping filter (18) is fixedly connected to the surface of the transmission mesh belt (16) by an elastic strip (17). Multiple scraping filters (18) are provided. A collection hopper (19) is fixedly connected to one side of the flotation tank (12), and an inclined barrier filter (110) is fixedly connected to one side of the flotation tank (12).

5. A saturated tower wastewater recycling system according to claim 3, characterized in that, The upper, middle and lower layers of the distillation column (24) are respectively fixedly connected to a perforated sieve plate (27), a distributor (28) and a stainless steel corrugated packing (29). The end of the connecting pipe three (26) passes through the distillation column (24) and connects to the distributor (28). The top of the distillation column (24) is fixedly connected to the discharge pipe one.

6. The saturated tower wastewater recycling system according to claim 5, characterized in that, Feed pumps are installed on the second (23), the third (26) and the three-way pipe (25). A control valve is installed on the three-way pipe (25) at the distillation column (24). Heaters are installed on the flotation tank (12) and the distillation column (24).

7. A saturated tower wastewater recycling system according to claim 4, characterized in that, The purification tank (31) is fixedly connected to a partition plate two. The nanofiltration membrane core (32) and the reverse osmosis membrane core (33) are both fixedly connected between the bottom of the partition plate two and the purification tank (31). The inner cavity of the reverse osmosis membrane core (33) is connected to the inside of the purification tank (31) above the partition plate two. The top of the purification tank (31) is fixedly connected to a discharge pipe two.

8. A saturated tower wastewater recycling system according to claim 7, characterized in that, The upper part of the partition 2 is provided with a strong acid cation exchange resin layer, a strong base anion exchange resin layer and a mixed cation and anion resin layer from bottom to top.

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