Method for treating and recycling high-organic-matter high-salt wastewater

Abstract

The invention relates to a method for treating and recycling high-organic-matter and high-salt wastewater, and discloses a method for treating and recycling high-organic-matter and high-salt wastewater, which comprises the following steps of: performing primary concentration on the wastewater through an electrodialysis technology, removing COD (Chemical Oxygen Demand) in a primary concentrated solution through electrochemical reaction, and performing secondary concentration on the concentrated solution through a disc tube type reverse osmosis membrane; according to the wastewater treatment and resource utilization process, high-concentration salt concentrated liquid with low COD residues and pure fresh water are obtained, after the pure fresh water generated through secondary concentration is used for diluting the high-COD fresh water obtained through primary concentration, mixed fresh water is subjected to A / O biochemical treatment, and the pure fresh water with low COD residues is obtained. And the residual high-concentration salt concentrated solution with low COD (Chemical Oxygen Demand) is recycled as a magnetic ion exchange resin regenerant, so that the resource recycling of the byproduct salt is realized, and pure fresh water is used as production reuse water, thereby achieving zero discharge of wastewater. The method is characterized in that an electrodialysis technology and an electrochemical reaction are combined with a disc tube type reverse osmosis membrane to carry out secondary concentration on a concentrated solution, so that a high-concentration salt concentrated solution with low COD (Chemical Oxygen Demand) residue is obtained.

Description

Technical Field

[0001] The present invention relates to a method for treating and resource-utilizing high-organic-matter, high-salt wastewater, involving the treatment of high-salt, high-organic-matter magnetic ion exchange resin regeneration wastewater and the recycling of sodium chloride and freshwater. The method belongs to the field of water treatment technology and particularly relates to a method for treating and resource-utilizing wastewater by using electrodialysis technology to concentrate the wastewater, remove COD from the primary concentrate by electrochemical reaction, and then secondary concentrate the concentrate through a disc-tube reverse osmosis membrane to obtain a high-concentration salt concentrate free of COD residue and pure freshwater. The pure freshwater produced by the secondary concentration is used to dilute the primary concentrated high-COD freshwater, and the mixed freshwater is subjected to A / O biochemical treatment to obtain pure freshwater free of COD residue. The high-concentration salt concentrate free of COD residue is reused as a magnetic ion exchange resin regeneration agent, achieving resource recycling of by-product salts, and the pure freshwater is used as production reuse water, achieving zero wastewater discharge. Background Art

[0002] Surface water contains high concentrations of organic matter. After using magnetic ion exchange resin to remove organic matter from the water, the saturated resin is regenerated with sodium chloride (edible salt) solution. The wastewater (raw water) produced by regeneration contains high concentrations of humic acid and sodium chloride. If it is discharged directly, it will cause serious pollution of surface water, groundwater and soil. The traditional method for treating such wastewater is to build a centralized temporary storage for treatment. However, it faces high storage and management costs, which are difficult for enterprises to afford and have become a problem that restricts the development of enterprises. Therefore, this type of wastewater is treated to reduce the chemical oxygen demand (COD) and content of the wastewater. Salt content, in order to reduce the pollution to the environment becomes particularly important. At present, the treatment processes for high-salt and high-organic wastewater mainly include physical and chemical methods and biological methods. Due to the high inorganic salt content in the wastewater, it has a strong inhibitory and toxic effect on microorganisms. The industry cannot use biological methods to directly treat wastewater in batches. Physical and chemical methods mainly include incineration, electrolysis, high-efficiency evaporation technology and membrane treatment technology. Among them, the incineration method is generally suitable for wastewater with a COD value greater than 100g / L, and has high energy consumption. The high-efficiency evaporation technology is for high-salt wastewater with a salt content of more than 40,000 mg / L and is not suitable for treating resins. For the wastewater generated by regeneration, the electrolysis method uses the high conductivity of high-salt wastewater to make the organic electrolyte solution undergo a series of redox reactions to generate water-insoluble substances, which are removed by precipitation or generation of harmless gases to reduce COD. The effect of electrolysis on wastewater treatment is strongly correlated with salt concentration. Wastewater with higher salt concentration has higher conductivity, which can improve the transmission effect of current and make the electrolysis reaction more complete and rapid. However, too high salt concentration will lead to an increase in the osmotic pressure of the wastewater, thereby affecting the reaction rate and stability of the electrolysis. After repeated experiments, it was found that the electrolysis method is effective for resin regeneration. The high-salt and high-organic wastewater generated is directly treated, and the removal effect of organic matter is poor. There are still many organic residues in the treated wastewater. Membrane treatment technologies include membrane distillation, reverse osmosis and electrodialysis. The high-salt and high-organic wastewater generated by resin regeneration is treated by membrane treatment technology. The products are low-salt fresh water and high-salt concentrate. The concentrate and fresh water contain high concentrations of organic matter. The fresh water cannot be directly used as production reuse water, and direct discharge will cause pollution to the environment. In addition, the sodium chloride concentration in the concentrate is low, and it cannot be directly recovered for resin regeneration, and the resource recycling of by-product salt cannot be achieved.

[0003] Publication No. CN118184039A discloses a method for treating resin adsorption regeneration liquid, comprising the following steps: S1, discharging the resin regeneration waste liquid into a raw water tank, and then passing it through a lift pump into a pretreatment filtration system to remove a small amount of particulate matter in the desorption liquid to reduce the impact on subsequent processes; S2, the pretreated water enters an electrodialysis system, injecting an electrolyte into the anode chamber and the cathode chamber respectively, using sodium hydroxide as the electrolyte, injecting the resin desorption liquid into the desalination chamber, and injecting pure water into the concentration chamber, with the volume ratio of the desalination chamber to the concentration chamber being 1.2:1~2:1, electrodialysis treatment is carried out; Publication No. CN118270956A discloses a bipolar membrane electrodialysis treatment system and a wastewater treatment method, which pre-precipitates the raw water of mine wastewater to remove solid suspended particles with higher density, then adds alkali and barium salt chemicals for mixed precipitation to remove heavy metals and sulfates, and the effluent is filtered and enters the bipolar membrane electrodialysis unit, thereby achieving the treatment of heavy metals and sulfates in the mine wastewater and the resource recovery and utilization of acid; Publication No. CN107224999A discloses a resin desorption liquid disposal method based on electrodialysis technology, which includes: using an electrodialysis device to separate organic components and salts in the resin desorption liquid; concentrating The salinity of the desalinated liquid can reach about 15%, and the CODMn is lower than 100 mg / L, which can be used directly as a regeneration agent. The salinity of the desalinated liquid is lower than 1%. Coagulation, sedimentation and ozone oxidation can effectively reduce its organic matter content, and can be biochemically treated. Publication No. CN117964161A discloses a high-salt wastewater treatment method and a high-salt wastewater treatment device, which separates and recovers high-salt ions in the wastewater by subjecting the wastewater to bipolar membrane electrodialysis-electroadsorption treatment, and reduces the concentration of Cl-, SO42-, H2PO4- and other ions. By mixing the first mixed liquid with a magnetic iron-based heterogeneous catalyst, the metal ions in the wastewater are reduced and toxic pollutants are degraded through the Fenton reaction. Publication No. CN11 7446914A discloses a method for resource-based treatment of organic high-salt wastewater and its application, comprising the following steps: 1) raw water is filtered through a nanofiltration membrane for multi-stage filtration to produce a retentate and a permeate; 2) the permeate produced in step 1) is filtered through a first reverse osmosis membrane to produce a retentate and a permeate; 3) the permeate produced after filtration through the first reverse osmosis membrane is added to the multi-stage filtration, and the retentate produced after filtration through the first reverse osmosis membrane is passed through an electrodialysis device to produce a light brine and a concentrated brine; 4) the retentate produced in the last stage of the multi-stage filtration is filtered through a second permeation membrane to produce fresh water and a product, through processes such as nanofiltration, reverse osmosis and electrodialysis; the above patent adopts electrodialysis or electrodialysis and reverse osmosis The high-salt, high-organic wastewater is treated using a combination of membrane treatment technologies, with the resulting concentrated water and fresh water used directly in production processes. However, when the aforementioned treatment method or equipment is used to treat wastewater from magnetic ion exchange resin regeneration, the wastewater produced contains high concentrations of sodium chloride and humic acid. The types of organic matter, salt types, and concentrations in the regenerated wastewater differ from those in the aforementioned wastewater. After the applicant uses the aforementioned method to treat the regenerated wastewater, the resulting concentrate and fresh water contain high concentrations of organic matter, making the fresh water unusable as production reuse water. Furthermore, the low sodium chloride concentration in the concentrate also prevents direct recycling for resin regeneration, preventing the recycling of by-product salts. Summary of the Invention

[0004] To improve the above situation, the present invention provides a method for treating and resource-utilizing high-organic-matter, high-salt wastewater. The method includes a method for concentrating the wastewater using electrodialysis technology, removing COD from the primary concentrate through an electrochemical reaction, and then concentrating the concentrate twice through a disc-tube reverse osmosis membrane to obtain a high-salt concentrate with low COD residue and pure fresh water. The pure fresh water produced by the secondary concentration is used to dilute the primary concentrated high-COD fresh water, and the mixed fresh water is subjected to A / O biochemical treatment to obtain pure fresh water with low COD residue. The high-salt concentrate with low COD residue is reused as a regeneration agent for magnetic ion exchange resin, realizing the resource recycling of by-product salts, and the pure fresh water is used as production reuse water, achieving zero wastewater discharge.

[0005] The method for treating and recycling high-organic and high-salt wastewater of the present invention is achieved as follows: The method for treating and recycling high-organic and high-salt wastewater of the present invention is characterized in that it specifically comprises the following steps: (1) The high-salt and high-organic wastewater (raw water) generated by the regeneration of the magnetic ion exchange resin is subjected to coagulation and sedimentation treatment by adding drugs, and the sediment is filtered to remove the suspended matter in the raw water. The raw water after the suspended matter is removed is then passed into the electrodialysis equipment; Preferably, the turbidity of the raw water after the suspended matter is removed is reduced, which can increase the life and flux of the subsequent electrodialysis equipment; (2) Electrodialysis treatment of raw water to obtain primary concentrated water with high COD and primary fresh water; The primary concentrated water after electrodialysis treatment is subjected to electrochemical reaction to remove COD, and ozone is introduced during the reaction process to obtain primary concentrated water with low COD residual; (4) The primary concentrated water with low COD residue is further concentrated through a disc-tube reverse osmosis membrane (DTRO) to obtain secondary concentrated water with low COD residue and secondary fresh water with low COD residue; Preferably, the sodium chloride concentration of the secondary concentrated water is greater than the sodium chloride concentration of the primary concentrated water; Preferably, the secondary concentrated water with low COD residue is reused as a regeneration agent for magnetic ion exchange resin; (5) Mixing the secondary fresh water with low COD residue with the primary fresh water, diluting the primary fresh water, and then subjecting it to A / O biochemical treatment to remove COD from the mixed fresh water; Preferably, the mixed fresh water after COD removal is used as production return water to achieve zero wastewater discharge. Beneficial effects

[0006] 1. Electrodialysis technology, electrochemical reaction combined with disc-tube reverse osmosis membrane is used to conduct secondary concentration of the concentrate to obtain a high-concentration salt concentrate with low COD residue, which is reused as a regeneration agent for magnetic ion exchange resin to achieve resource recycling of by-product salt.

[0007] Second, the purified fresh water produced by secondary concentration is used to dilute the high-COD fresh water concentrated in the first concentration. The mixed fresh water is then treated with A / O biochemical treatment to obtain purified fresh water with low COD residue for use as production reuse water, achieving zero wastewater discharge.

[0008] 3. The secondary fresh water with low COD residue is mixed with the primary fresh water. The sodium chloride content in the mixed water is low, which can meet the biochemical water inlet requirements. At the same time, the COD content of the mixed fresh water is low, which can ensure the biochemical treatment effect and make the effluent water quality meet the requirements of production reuse water. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a process flow chart of a method for treating and recycling high-organic-matter-high-salt wastewater according to the present invention; DETAILED DESCRIPTION Example 1

[0010] The present invention provides a method for treating and recycling high-organic-matter-high-salt wastewater, which is characterized by comprising the following steps: (1) The high-salt and high-organic wastewater (raw water) generated by the regeneration of the magnetic ion exchange resin is subjected to coagulation and sedimentation treatment by adding drugs, and the sediment is filtered to remove the suspended matter in the raw water. The raw water after the suspended matter is removed is then passed into the electrodialysis equipment; Preferably, the turbidity of the raw water after the suspended matter is removed is reduced, which can increase the life and flux of the subsequent electrodialysis equipment; Preferably, the high-salt and high-organic wastewater (raw water) produced by the regeneration of the magnetic ion exchange resin has a COD content of 5674 mg / L and a sodium chloride concentration of 2.73%; (2) Electrodialysis treatment of raw water to obtain primary concentrated water with high COD and primary fresh water; Preferably, the COD content of the primary concentrated water is 1522 mg / L, and the sodium chloride concentration is 4.70%; the COD content of the primary fresh water is 4786 mg / L, and the sodium chloride concentration is 0.61%; (3) The primary concentrated water after electrodialysis treatment is subjected to electrochemical reaction to remove COD, and ozone is introduced during the reaction process to obtain primary concentrated water with low COD residue; Preferably, the dosage of ozone is 40 mg / L; Preferably, the COD content of the low COD residual primary concentrated water is 200 mg / L, and the sodium chloride concentration is 4.65%; When ozone is introduced into the electrochemical reaction process, high COD primary concentrated water undergoes COD degradation treatment through electrochemical reaction. H+ in the water is reduced on the cathode to release hydrogen. The mixture of hydrogen and air has the risk of explosion. Introducing ozone into the electrochemical reaction process can effectively suppress the production of hydrogen and reduce the risk of explosion. The design of first subjecting the raw water to electrodialysis treatment and then removing COD from the concentrated water through electrochemical reaction can effectively reduce the COD concentration after the electrodialysis reaction because the organic matter in the magnetic ion exchange resin regeneration wastewater is humic acid, which has a negative charge. The total amount of hydrogen in the electrochemical reaction is reduced, thereby reducing the risk of explosion. (4) The primary concentrated water with low COD residue is further concentrated through a disc-tube reverse osmosis membrane (DTRO) to obtain secondary concentrated water with low COD residue and secondary fresh water with low COD residue; Preferably, the sodium chloride concentration of the secondary concentrated water is greater than the sodium chloride concentration of the primary concentrated water; Preferably, the sodium chloride concentration of the secondary concentrated water reaches 7.50%, Preferably, the secondary concentrated water with low COD residue is reused as a regeneration agent for magnetic ion exchange resin; (5) Mixing the secondary fresh water with low COD residue with the primary fresh water, diluting the primary fresh water, and then subjecting it to A / O biochemical treatment to remove COD from the mixed fresh water; Preferably, the mixed fresh water after COD removal is used as production return water to achieve zero wastewater discharge; Preferably, the COD of the mixed fresh water after COD removal is reduced to 80 mg / L; In the design of introducing ozone during the electrochemical reaction, when high-COD primary concentrated water undergoes COD degradation treatment through the electrochemical reaction, H+ in the water is reduced at the cathode to release hydrogen. The mixture of hydrogen and air has the risk of explosion. The introduction of ozone during the electrochemical reaction can effectively suppress the production of hydrogen and reduce the risk of explosion. The design of first subjecting the raw water to electrodialysis treatment and then removing COD from the concentrated water through electrochemical reaction can effectively reduce the COD concentration after the electrodialysis reaction because the organic matter in the magnetic ion exchange resin regeneration wastewater is humic acid, which has a negative charge. The total amount of hydrogen in the electrochemical reaction is reduced, thereby reducing the risk of explosion. The design of removing COD from the primary concentrated water through an electrochemical reaction to obtain primary concentrated water with low COD residue, and then passing the primary concentrated water through a disc-tube reverse osmosis membrane (DTRO) for further concentration treatment can effectively reduce the organic matter load, reduce pollution and clogging of the reverse osmosis membrane, extend the service life of the membrane, and reduce the maintenance and replacement frequency of the reverse osmosis membrane. At the same time, during the continuous water treatment process, it can prevent the accumulation of COD pollutants on the reverse osmosis membrane from causing secondary pollution to the effluent, thereby improving the water treatment effect; The design of mixing the secondary fresh water with low COD residue with the primary fresh water and diluting the primary fresh water before performing the A / O biochemical treatment, wherein the low-salt fresh water meets the biochemical water inlet requirements, does not strongly inhibit or toxic the microorganisms in the biochemical system, and can effectively reduce the organic load of the A / O treatment system by diluting the COD concentration in the primary fresh water, alleviating the treatment pressure of the A / O treatment system. At the same time, the dilution can effectively stabilize the influent water quality, help reduce the operational fluctuations of the A / O treatment system, prevent the impact of large COD concentration fluctuations on microorganisms, and improve the stability of the A / O treatment system. The raw water can be subjected to secondary concentration and COD removal treatment to obtain high-concentration salt concentrate without COD residue and pure fresh water. The pure fresh water produced by the secondary concentration is used to dilute the high-COD fresh water concentrated once. The mixed fresh water is then subjected to A / O biochemical treatment. The high-concentration salt concentrate without COD residue is reused as a regeneration agent for the magnetic ion exchange resin, realizing the resource recycling of by-product salt. The pure fresh water is used as production reuse water, achieving the goal of zero wastewater discharge.

[0011] It should be noted that, unless otherwise expressly specified or limited, the terms "placed in," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections such as hemming, rivet connection, pin connection, adhesive connection, and welding connection; detachable connections such as threaded connection, snap connection, and hinge connection; or integral connection; electrical connection; direct connection; indirect connection through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

Claims

1. A method for treating and recycling high-organic-matter-high-salt wastewater, characterized by: Specifically, the process includes the following steps: (1) treating the high-salt and high-organic wastewater (raw water) generated by the regeneration of the magnetic ion exchange resin with coagulation and sedimentation, filtering the sediment to remove suspended solids in the raw water, and passing the raw water after the suspended solids are removed into the electrodialysis equipment; (2) treating the raw water with electrodialysis to obtain primary concentrated water with high COD and primary fresh water; (3) removing COD from the primary concentrated water after the electrodialysis treatment by electrochemical reaction, and introducing ozone during the reaction to obtain primary concentrated water with low COD residue; (4) further concentrating the primary concentrated water with low COD residue through a disc-tube reverse osmosis membrane (DTRO) to obtain secondary concentrated water with low COD residue and secondary fresh water with low COD residue; (5) mixing the secondary fresh water with low COD residue with the primary fresh water, diluting the primary fresh water, and then subjecting it to A / O biochemical treatment to remove COD from the mixed fresh water.

2. The method for treating and recycling high-organic-matter-high-salt wastewater according to claim 1, characterized in that The high-salt and high-organic matter wastewater (raw water) generated by the regeneration of the magnetic ion exchange resin has a COD content of 5674 mg / L and a sodium chloride concentration of 2.73%.

3. The method for treating and recycling high-organic-matter-high-salt wastewater according to claim 1, characterized in that The COD content of the primary concentrated water is 1522 mg / L, and the sodium chloride concentration is 4.70%.

4. The method for treating and recycling high-organic-matter-high-salt wastewater according to claim 1, characterized in that The dosage of ozone is 40 mg / L.

5. The method for treating and recycling high-organic-matter-high-salt wastewater according to claim 1, characterized in that The COD content of the low-COD residual primary concentrated water is 200 mg / L, and the sodium chloride concentration is 4.65%.

6. The method for treating and recycling high-organic-matter-high-salt wastewater according to claim 1, characterized in that The sodium chloride concentration of the secondary concentrated water is greater than the sodium chloride concentration of the primary concentrated water.

7. The method for treating and recycling high-organic-matter-high-salt wastewater according to claim 1, characterized in that The mixed fresh water after COD removal is used as production return water, achieving zero wastewater discharge.

8. The method for treating and recycling high-organic-matter-high-salt wastewater according to claim 7, characterized in that The COD of the mixed fresh water after the COD removal is reduced to 80 mg / L.

9. The method for treating and recycling high-organic-matter-high-salt wastewater according to claim 1, characterized in that The primary fresh water has a COD content of 4786 mg / L and a sodium chloride concentration of 0.61%.

10. The method for treating and recycling high-organic-matter-high-salt wastewater according to claim 1, characterized in that The sodium chloride concentration of the secondary concentrated water reaches 7.50%, and the secondary concentrated water with low COD residue is reused as a regeneration agent for magnetic ion exchange resin.

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