A method for wastewater treatment and water recovery

Abstract

The application relates to the technical field of sewage treatment, and discloses a water recovery treatment method for sewage treatment, which comprises a high-density clarification reaction tank, a coking water UF membrane tank, a reverse osmosis membrane device, a high-density fluorine removal tank, a chemical fluorine removal tank, a chemical hardness removal tank and a regenerated waste liquid collecting tank. Resin is added to the high-density clarification reaction tank, and calcium carbonate ions in mixed concentrated water are adsorbed by the resin, so that the hardness in the mixed concentrated water is removed, and fouling in subsequent treatment of the mixed concentrated water with high hardness is avoided; defluorination and hardness removal are carried out on the regenerated waste liquid C in the chemical fluorine removal tank, the hardness removal of the regenerated waste liquid C is facilitated, the hardness removal effect of the regenerated waste liquid C is effectively avoided due to the fact that the reverse osmosis concentrated water contains a scale inhibitor, backwash wastewater can be separately removed of impurities by being delivered to the chemical hardness removal tank, the problem that suspended matters are difficult to precipitate due to large water quantity does not exist, and even secondary precipitation can be carried out in the high-density fluorine removal tank, and the consumption of reagents is reduced.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method for treating wastewater by recycling. Background Technology

[0002] Domestic sewage and industrial wastewater contain large amounts of organic pollutants and pathogens. If discharged without treatment, they will harm the surrounding environment and water bodies, and seriously affect human health. Therefore, strict biological and disinfection treatment is essential to minimize the impact on the environment and water bodies. With increasingly stringent environmental protection requirements and growing water scarcity, reclaimed water is gradually being recycled and reused for fire fighting, landscaping, street cleaning, and vehicle washing. Simultaneously, sludge is regularly discharged for use as agricultural fertilizer, achieving a win-win situation for both social and economic benefits.

[0003] The overall process of the greywater system is PMUF submerged ultrafiltration + LERO reverse osmosis membrane treatment system + RO concentrate multi-component defluorination, hardening, silica removal and impurity removal pretreatment system + nanofiltration NF-RO salt separation system.

[0004] Regarding the above-mentioned and existing related technologies, the inventors believe that the following defects often exist: in existing greywater reuse treatment systems, the defluorination and hardness removal effects on concentrated water are not good, and there is a phenomenon of wasting reagents. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the existing technology has the disadvantages of poor defluorination and hardness removal effect on concentrated water and waste of reagents. To this end, we propose a wastewater recycling treatment method.

[0006] To achieve the above objectives, this application adopts the following technical solution: a method for treating greywater from wastewater treatment, comprising the following steps:

[0007] S1: The biochemical effluent and purified wastewater from the biochemical system are transported to the high-density clarification reaction tank and mixed to obtain mixed concentrated water;

[0008] S2: Add resin to the high-density clarification reaction tank to remove hardness from the mixed concentrate and generate regenerated waste liquid A. Regenerated waste liquid A is transported to the regenerated waste liquid collection tank, while the mixed concentrate is transported to the coking water UF membrane tank.

[0009] S3: The mixed concentrate is filtered through the coking water UF membrane tank and the reverse osmosis membrane unit to produce reverse osmosis concentrate and reclaimed water A. Reclaimed water A is sent to the reclaimed water recycling tank for reuse, while the reverse osmosis concentrate is sent to the high-density defluoridation tank.

[0010] S4: Defluoride the reverse osmosis concentrate in the high-density defluorination tank, and then send the reverse osmosis concentrate to the multi-media filter for filtration. The multi-media backwash wastewater is generated through backwashing and sent to the backwash water collection tank. Meanwhile, the reverse osmosis concentrate is sent to the cation softener for softening to produce softened concentrate. The softening process also generates regeneration waste liquid B, which is sent to the regeneration waste liquid collection tank.

[0011] S5: Regenerated waste liquid A and regenerated waste liquid B are mixed in the regenerated waste liquid collection tank to obtain regenerated waste liquid C. Regenerated waste liquid C is transported to the chemical defluorination tank for defluorination and hardening. After hardening treatment, regenerated waste liquid C is transported to the chemical hardening tank.

[0012] S6: Backwash wastewater is output to the chemical hardening tank, where it undergoes hardening removal and sedimentation with regeneration waste liquid C. The reverse osmosis concentrate precipitated on the upper layer of the backwash wastewater and regeneration waste liquid C is then transported to the high-density defluorination tank.

[0013] S7: The reverse osmosis concentrate is transported to the high-density defluorination tank for defluorination. The steps in S4 above are repeated to generate backwash wastewater and regeneration waste liquid B. The steps in S5 and S6 above are repeated to remove hardness and defluorination from the backwash wastewater and regeneration waste liquid C.

[0014] S8: The softened concentrate continues to flow, and after being filtered through the concentrate UF membrane tank, it is sent to the NF-RO desalination system, ultimately yielding reclaimed water B that meets the recycling standards.

[0015] Preferably, sodium carbonate needs to be added to the biological effluent in S1 in the biological system, and liquid alkali is added in the high-density clarification reaction tank to adjust the pH value of the biological effluent to be within the range of 8.0-9.0.

[0016] Preferably, the coking water UF membrane tank, reverse osmosis membrane device, high-density defluoridation tank, cation softener, and concentrate UF membrane tank conveying end are all equipped with a corresponding product water tank.

[0017] Preferably, hollow fiber membranes, flat sheet membranes, and UF membrane elements are installed in the coking water UF membrane tank and the concentrate UF membrane tank in S3 and S8, and aerators and drain outlets are installed inside. The reverse osmosis membrane device is equipped with ultrafiltration membranes and security filters.

[0018] Preferably, in the S4 high-density defluoridation tank, calcium salts and aluminum agents are added to react with fluoride ions to produce fluoride precipitates or complexes. The high-density defluoridation tank is equipped with a clarification tank, in which the reverse osmosis concentrate stays for 2-4 hours.

[0019] Preferably, in the chemical defluorination tank of S5, calcium chloride is added to defluorinate the regenerated waste liquid C, and sodium hydroxide and sodium carbonate are added.

[0020] Preferably, the chemical hardening tank in S6 is equipped with a screen and activated carbon, and calcium hydroxide and sodium carbonate are added. The backwash wastewater and regeneration waste liquid C stay in the chemical hardening tank for 30-60 minutes.

[0021] Preferably, the multi-media filter and the cation softener in S4 are backwashed every 8-24 hours, depending on the concentrate quality and filtration pressure difference, with each backwash lasting 5-10 minutes.

[0022] Preferably, the coking water UF membrane tank in S3 is connected to a scale inhibitor tank and a reducing agent tank, and the dosage of scale inhibitor and reducing agent is set to 5 ppm.

[0023] Preferably, the regenerated waste liquid A in S2 is 150m³ over 3 days. 3 The total hardness concentration is 1500 mg / L, and the total hardness concentration of the reverse osmosis concentrate after treatment by the reverse osmosis membrane device in S3 is 100 mg / L.

[0024] The technical effects and advantages of this invention are as follows:

[0025] In this invention, resin is added to a high-density clarification reaction tank. The resin adsorbs calcium carbonate ions in the mixed concentrate, thereby removing hardness from the mixed concentrate and preventing scaling in subsequent treatment due to high hardness. The regenerated wastewater C undergoes defluorination and hardness removal in a chemical defluorination tank, facilitating separate hardness removal of the regenerated wastewater C. This effectively avoids the impact of scale inhibitors in the reverse osmosis concentrate on the hardness removal effect of the regenerated wastewater C. By transporting backwash wastewater to a chemical hardness removal tank, impurities in the backwash wastewater can be removed separately, avoiding the problem of suspended solids being difficult to settle due to large water volume. Secondary sedimentation can even occur in the high-density defluorination tank, reducing reagent consumption. Attached Figure Description

[0026] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts:

[0027] Figure 1 This is a schematic flowchart of a wastewater treatment method for recycling and treating wastewater according to the present invention. Detailed Implementation

[0028] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0029] Reference Figure 1 As shown, the present invention provides a technical solution: a method for treating and recycling greywater from wastewater treatment, comprising the following steps:

[0030] S1: The biochemical effluent and purified wastewater from the biochemical system are transported to the high-density clarification reaction tank and mixed to obtain mixed concentrated water;

[0031] By mixing the biochemical effluent and the purified wastewater in a high-density clarification reaction tank, the bicarbonate ions in the biochemical effluent react with the liquid alkali to convert into carbonate ions when the pH value is adjusted by adding liquid alkali. The carbonate ions then react with the calcium ions in the mixed concentrate to form calcium carbonate, thereby reducing the calcium hardness of the mixed concentrate.

[0032] S2: Add resin to the high-density clarification reaction tank to remove hardness from the mixed concentrate and generate regenerated waste liquid A. Regenerated waste liquid A is transported to the regenerated waste liquid collection tank, while the mixed concentrate is transported to the coking water UF membrane tank.

[0033] By adding resin to the high-density clarification reaction tank, the resin adsorbs calcium carbonate and other ions in the mixed concentrate, thereby removing the hardness of the mixed concentrate and preventing scaling from forming in subsequent treatments due to high hardness.

[0034] S3: The mixed concentrate is filtered through the coking water UF membrane tank and the reverse osmosis membrane unit to produce reverse osmosis concentrate and reclaimed water A. Reclaimed water A is sent to the reclaimed water recycling tank for reuse, while the reverse osmosis concentrate is sent to the high-density defluoridation tank.

[0035] By filtering the mixed concentrate through a coking water UF membrane tank and a reverse osmosis membrane unit, water molecules and small molecules can pass through the membrane pores to form greywater under gravity or pump pressure, while pollutants are retained by the membrane to form reverse osmosis concentrate, which facilitates the improvement of the recovery and utilization rate of greywater A.

[0036] S4: Defluoride the reverse osmosis concentrate in the high-density defluorination tank, and then send the reverse osmosis concentrate to the multi-media filter for filtration. The multi-media backwash wastewater is generated through backwashing and sent to the backwash water collection tank. Meanwhile, the reverse osmosis concentrate is sent to the cation softener for softening to produce softened concentrate. The softening process also generates regeneration waste liquid B, which is sent to the regeneration waste liquid collection tank.

[0037] By adding calcium salts and aluminum agents to the reverse osmosis concentrate in a high-density defluorination tank, chemical precipitation and coagulation sedimentation are carried out, which removes fluoride ions and other suspended particles from the reverse osmosis concentrate through flocculation and facilitates sedimentation and separation. Then, the reverse osmosis concentrate is filtered again through a multi-media filter to remove particulate impurities. The cation softener exchanges calcium and magnesium ions in the reverse osmosis concentrate with the resin particles inside, so that the calcium and magnesium ions in the reverse osmosis concentrate are adsorbed and retained in the cation softener, which facilitates the softening of the concentrate.

[0038] S5: Regenerated waste liquid A and regenerated waste liquid B are mixed in the regenerated waste liquid collection tank to obtain regenerated waste liquid C. Regenerated waste liquid C is transported to the chemical defluorination tank for defluorination and hardening. After hardening treatment, regenerated waste liquid C is transported to the chemical hardening tank.

[0039] S6: Backwash wastewater is output to the chemical hardening tank, where it undergoes hardening removal and sedimentation with regeneration waste liquid C. The reverse osmosis concentrate precipitated on the upper layer of the backwash wastewater and regeneration waste liquid C is then transported to the high-density defluorination tank.

[0040] S7: The reverse osmosis concentrate is transported to the high-density defluorination tank for defluorination. The steps in S4 above are repeated to generate backwash wastewater and regeneration waste liquid B. The steps in S5 and S6 above are repeated to remove hardness and defluorination from the backwash wastewater and regeneration waste liquid C.

[0041] By using the regenerated waste liquid C in a chemical defluorination tank for defluorination and hardening, it is convenient to perform hardening removal on the regenerated waste liquid C separately. This can effectively avoid the hardening removal effect of the regenerated waste liquid C being affected by the scale inhibitor contained in the reverse osmosis concentrate.

[0042] By transporting backwash wastewater to a chemical desulfurization tank, impurities in the backwash wastewater can be removed separately, avoiding the problem of suspended solids being difficult to settle due to large water volume. Secondary sedimentation can even occur in the high-density defluoridation tank. This avoids the problem of backwash wastewater and reverse osmosis concentrate entering the high-density defluoridation tank, which would cause the upward flow velocity in the high-density defluoridation tank to increase and the flow rate to be too large. Changes in water flow velocity make it difficult for flocculent impurities in the backwash wastewater to settle stably and increases the consumption of reagents. This allows the flocculent impurities in the backwash wastewater to first flocculate and settle in the chemical desulfurization tank.

[0043] S8: The softened concentrate continues to flow, and after being filtered through the concentrate UF membrane tank, it is sent to the NF-RO desalination system, ultimately yielding reclaimed water B that meets the recycling standards.

[0044] After being filtered through a concentrated water UF membrane tank, the softened concentrate is sent to the NF-RO desalination system to obtain reclaimed water B that meets the recycling standards. This improves the treatment efficiency of reclaimed water recycling and reduces the amount of chemicals consumed during the treatment process.

[0045] Reference Figure 1As shown in this implementation plan: Sodium carbonate needs to be added to the biochemical effluent in S1 in the biochemical system, and liquid alkali is added in the high-density clarification reaction tank to adjust the pH value of the biochemical effluent to be within the range of 8.0-9.0.

[0046] Adding sodium carbonate to the biochemical effluent in the biochemical system can buffer the pH of the water, keeping the pH of the effluent within the range of 7.5-8.5 and preventing a rapid drop in pH. Adding liquid alkali to the high-density clarification tank to adjust the pH to the range of 8.0-9.0 facilitates the conversion of bicarbonate ions in the concentrated mixed water into carbonate ions, thereby reducing the consumption of sodium carbonate and other reagents.

[0047] Reference Figure 1 As shown in this implementation scheme: the coking water UF membrane tank, the reverse osmosis membrane device, the high-density defluorination tank, the cation softener, and the concentrate UF membrane tank delivery end are all equipped with matching product water tanks.

[0048] The coking water UF membrane tank, reverse osmosis membrane unit, high-density defluoridation tank, cation softener, and concentrate UF membrane tank are all equipped with matching product water tanks at their respective delivery ends. This allows for the collection and sedimentation of the concentrate after treatment by these systems, improving the cleanliness of the concentrate before it is transported to the next process.

[0049] Reference Figure 1 As shown in this implementation scheme: hollow fiber membranes, flat sheet membranes and UF membrane elements are installed in the coking water UF membrane tank and the concentrate UF membrane tank in S3 and S8. Aerators and drain outlets are installed inside. Ultrafiltration membranes and security filters are installed inside the reverse osmosis membrane device.

[0050] The coking water UF membrane tank is equipped with hollow fiber, flat sheet membrane and UF membrane elements, which facilitates the removal of suspended solids, colloids and large molecular organic matter in the mixed concentrate, and avoids clogging of the ultrafiltration membrane in the reverse osmosis membrane device. The reverse osmosis membrane device allows water molecules to pass through the membrane pores to form greywater, while calcium and magnesium ions and organic matter are retained by the membrane to form reverse osmosis concentrate.

[0051] Reference Figure 1 As shown in this implementation scheme: calcium salt and aluminum agent are added to the high-density defluoridation tank in S4 to react with fluoride ions to produce fluoride precipitates or complexes. The high-density defluoridation tank is equipped with a clarification tank, and the reverse osmosis concentrate stays in the clarification tank for 2-4 hours.

[0052] The high-density defluoridation tank is equipped with a clarification tank. The reverse osmosis concentrate stays in the clarification tank for 2-4 hours, which facilitates the reaction between calcium salts and aluminum agents and fluoride ions in the reverse osmosis concentrate. It also facilitates the precipitation and separation of fluorides or complexes in the reverse osmosis concentrate in the clarification tank. The top water separated from the reverse osmosis concentrate is then transported to a multi-media filter for filtration.

[0053] Reference Figure 1 As shown in this implementation scheme: In the chemical defluorination tank in S5, calcium chloride is added to defluorinate the regenerated waste liquid C, and sodium hydroxide and sodium carbonate are added.

[0054] By removing hardness and fluoride from the regenerated wastewater C separately, it is easier to avoid the scale inhibitor in the mixed concentrate affecting the hardness removal effect of the regenerated wastewater C, thereby reducing the consumption of reagents.

[0055] Reference Figure 1 As shown in this implementation scheme: the chemical hardening tank in S6 is equipped with a grid and activated carbon, and calcium hydroxide and sodium carbonate are added. The backwash wastewater and regeneration waste liquid C stay in the chemical hardening tank for 30-60 minutes.

[0056] The chemical hardening tank is equipped with a screen and activated carbon to facilitate the removal of large particulate impurities from backwash wastewater and regeneration wastewater C. At the same time, the addition of calcium hydroxide and sodium carbonate can form large flocs, which encapsulate the precipitated particles and accelerate sedimentation. After settling in the chemical hardening tank for 30-60 minutes, the supernatant of the backwash wastewater and regeneration wastewater C is transported to the high-density defluoridation tank for secondary sedimentation and defluorination with the reverse osmosis concentrate, thus avoiding the presence of a large amount of suspended solids in the high-density defluoridation tank.

[0057] Reference Figure 1 As shown in this implementation scheme: the multi-media filter and the cation softener in S4 are backwashed every 8-24 hours according to the concentrate water quality and filtration pressure difference, and each backwash lasts for 5-10 minutes.

[0058] The multi-media filter and the cation softener are backwashed every 8-24 hours, with each backwash lasting 5-10 minutes. This helps to prevent suspended solids and scale impurities in the reverse osmosis concentrate from adhering to the filter media surface and affecting the filtration efficiency of the multi-media filter and the cation softener.

[0059] Reference Figure 1 As shown, the coking water UF membrane tank in S3 is connected to a scale inhibitor tank and a reducing agent tank, and the dosage of scale inhibitor and reducing agent is set to 5 ppm.

[0060] The coking water UF membrane tank is connected to scale inhibitor tanks and reducing agent tanks, which helps prevent scale formation on the ultrafiltration membranes inside the coking water UF membrane tank and reverse osmosis unit by mixed concentrated water, thus avoiding affecting the filtration effect of the coking water UF membrane tank and reverse osmosis unit.

[0061] Reference Figure 1 As shown in this implementation plan: In S2, the regenerated waste liquid A is 150m³ after 3 days. 3 The total hardness concentration is 1500 mg / L, and the total hardness concentration of the reverse osmosis concentrate after treatment by the reverse osmosis membrane device in S3 is 100 mg / L.

[0062] By treating the regenerated waste liquid A separately from the reverse osmosis concentrate, the scale inhibitor used in the reverse osmosis concentrate treatment will not flow into the regenerated waste liquid A, thus affecting the hardness removal effect of the mixed regenerated waste liquid C. At the same time, it can effectively prevent the high hardness of the regenerated waste liquid A from affecting the hardness treatment effect of the reverse osmosis concentrate.

[0063] Working principle: Users transport the biochemical effluent and purified wastewater from the biochemical system to the high-density clarification reaction tank, where they are mixed to obtain a mixed concentrate. When liquid alkali is added to adjust the pH value, the bicarbonate ions in the biochemical effluent react with the liquid alkali to convert into carbonate ions. The carbonate ions then react with the calcium ions in the mixed concentrate to form calcium carbonate, thereby reducing the calcium hardness of the mixed concentrate. Resin is added to the high-density clarification reaction tank, which adsorbs calcium carbonate and other ions in the mixed concentrate, thereby removing the hardness of the mixed concentrate and preventing scaling in subsequent treatments due to high hardness. The regeneration wastewater A generated by the resin adsorption is transported to the regeneration wastewater collection tank.

[0064] After the mixed concentrate undergoes filtration treatment in the coking water UF membrane tank and reverse osmosis membrane unit, and with the addition of scale inhibitors and reducing agents, it is easier for water molecules and small molecules to permeate through the membrane pores under gravity or pump pressure to form greywater, while pollutants are retained by the membrane to form reverse osmosis concentrate. This facilitates the improvement of greywater A recovery and reuse rate. The reverse osmosis concentrate is then transported to the high-density defluoridation tank, where calcium salts and aluminum agents are added for chemical precipitation and coagulation sedimentation, allowing fluoride ions and other suspended particles in the reverse osmosis concentrate to pass through the defluoridation tank. Flocculation is used to remove impurities, which facilitates sedimentation and separation. Then, the reverse osmosis concentrate is filtered again through a multi-media filter to remove particulate impurities. The cation softener exchanges calcium and magnesium ions in the reverse osmosis concentrate with the resin particles inside, so that the calcium and magnesium ions in the reverse osmosis concentrate are adsorbed and retained in the cation softener, which facilitates the softening of the concentrate. The softened concentrate is filtered through the concentrate UF membrane tank and then sent to the NF-RO desalination system to finally obtain reclaimed water B that meets the recycling standards, thus improving the treatment efficiency of reclaimed water recycling.

[0065] The multi-media filter generates multi-media backwash wastewater through backwashing, which is then transported to a backwash water collection tank. Meanwhile, the cation softener generates regeneration waste liquid B through ion exchange and retention, which is also transported to a regeneration waste liquid collection tank. Regeneration waste liquid A and regeneration waste liquid B are mixed in the collection tank to obtain regeneration waste liquid C. Regeneration waste liquid C is then transported to a chemical defluorination tank for defluorination and hardening removal. This allows for separate hardening removal of regeneration waste liquid C, effectively avoiding the impact of scale inhibitors in the reverse osmosis concentrate on its hardening removal effect. Furthermore, the backwash wastewater is transported to the chemical hardening tank for separate impurity removal, avoiding the problem of suspended solids being difficult to settle due to large water volume. Secondary sedimentation can even be performed in the high-density defluorination tank, thereby reducing the consumption of chemicals.

[0066] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A method for treating and recycling greywater from wastewater, characterized in that, Includes the following steps: S1: The biochemical effluent and purified wastewater from the biochemical system are transported to the high-density clarification reaction tank and mixed to obtain mixed concentrated water; S2: Add resin to the high-density clarification reaction tank to remove hardness from the mixed concentrate and generate regenerated waste liquid A. Regenerated waste liquid A is transported to the regenerated waste liquid collection tank, while the mixed concentrate is transported to the coking water UF membrane tank. S3: The mixed concentrate is filtered through the coking water UF membrane tank and the reverse osmosis membrane unit to produce reverse osmosis concentrate and reclaimed water A. Reclaimed water A is sent to the reclaimed water recycling tank for reuse, while the reverse osmosis concentrate is sent to the high-density defluoridation tank. S4: Defluoride the reverse osmosis concentrate in the high-density defluorination tank, and then send the reverse osmosis concentrate to the multi-media filter for filtration. The multi-media backwash wastewater is generated through backwashing and sent to the backwash water collection tank. Meanwhile, the reverse osmosis concentrate is sent to the cation softener for softening to produce softened concentrate. The softening process also generates regeneration waste liquid B, which is sent to the regeneration waste liquid collection tank. S5: Regenerated waste liquid A and regenerated waste liquid B are mixed in the regenerated waste liquid collection tank to obtain regenerated waste liquid C. Regenerated waste liquid C is transported to the chemical defluorination tank for defluorination and hardening. After hardening treatment, regenerated waste liquid C is transported to the chemical hardening tank. S6: Backwash wastewater is output to the chemical hardening tank, where it undergoes hardening removal and sedimentation with regeneration waste liquid C. The reverse osmosis concentrate precipitated on the upper layer of the backwash wastewater and regeneration waste liquid C is then transported to the high-density defluorination tank. S7: The reverse osmosis concentrate is transported to the high-density defluorination tank for defluorination. The steps in S4 above are repeated to generate backwash wastewater and regeneration waste liquid B. The steps in S5 and S6 above are repeated to remove hardness and defluorination from the backwash wastewater and regeneration waste liquid C. S8: The softened concentrate continues to flow, and after being filtered through the concentrate UF membrane tank, it is sent to the NF-RO desalination system, ultimately yielding reclaimed water B that meets the recycling standards.

2. The wastewater recycling method according to claim 1, characterized in that: In S1, sodium carbonate needs to be added to the biological effluent in the biological system. Liquid alkali is added in the high-density clarification reaction tank to adjust the pH value of the biological effluent to be within the range of 8.0-9.

0.

3. The wastewater recycling method according to claim 1, characterized in that: The coking water UF membrane tank, reverse osmosis membrane device, high-density defluoridation tank, cation softener, and concentrate UF membrane tank delivery end are all equipped with a corresponding product water tank.

4. The wastewater recycling method according to claim 1, characterized in that: Hollow fiber membranes, flat sheet membranes, and UF membrane elements are installed in the coking water UF membrane tanks and concentrate UF membrane tanks in S3 and S8. Aerators and drain outlets are installed inside. Ultrafiltration membranes and security filters are installed inside the reverse osmosis membrane units.

5. The wastewater recycling method according to claim 1, characterized in that: In the S4 high-density defluoridation tank, calcium salts and aluminum agents are added to react with fluoride ions to produce fluoride precipitates or complexes. The high-density defluoridation tank is equipped with a clarification tank, in which the reverse osmosis concentrate stays for 2-4 hours.

6. The wastewater recycling method according to claim 1, characterized in that: In the S5 chemical defluorination tank, calcium chloride is added to defluorinate the regenerated waste liquid C, along with sodium hydroxide and sodium carbonate.

7. The wastewater recycling method according to claim 1, characterized in that: The chemical hardening tank in S6 is equipped with a screen and activated carbon, and calcium hydroxide and sodium carbonate are added. The backwash wastewater and regeneration waste liquid C stay in the chemical hardening tank for 30-60 minutes.

8. The wastewater recycling method according to claim 1, characterized in that: The multi-media filter and cation softener in S4 are backwashed every 8-24 hours, depending on the concentrate quality and filtration pressure difference, with each backwash lasting 5-10 minutes.

9. The wastewater recycling method according to claim 1, characterized in that: The S3 coking water UF membrane tank is connected to a scale inhibitor tank and a reducing agent tank, and the dosage of scale inhibitor and reducing agent is set to 5 ppm.

10. The wastewater recycling method according to claim 1, characterized in that: S2 waste liquid A waste liquid 3 days 150m 3 The total hardness concentration is 1500 mg / L, and the total hardness concentration of the reverse osmosis concentrate after treatment by the reverse osmosis membrane device in S3 is 100 mg / L.

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