Deep denitrification system and method for high-efficiency cyclic utilization of high-nitrogen desorption liquid

Abstract

The invention discloses a deep denitrification system and method for high-efficiency cyclic utilization of a high-nitrogen desorption solution, and belongs to the technical field of water treatment. The deep denitrification system comprises a filtering system, a resin system, a desorption liquid tank, a cleaning water tank, an efficient precipitation system and a high-salt denitrification system. The deep denitrification method comprises the following steps: adsorbing nitrate nitrogen in denitrification inlet water by using anion exchange resin, then desorbing by using a high-salt regeneration solution, removing sulfate radicals from the obtained high-nitrogen desorption solution through a high-efficiency precipitation system, removing nitrate nitrogen and carbonate / bicarbonate through a high-salt denitrification system in sequence, and discharging the obtained high-nitrogen desorption solution. And high-salt regenerated liquid with high sodium chloride purity is formed and recycled. The deep denitrification system and method can greatly reduce the consumption of sodium chloride salt and the discharge amount of waste brine, remarkably save the operation cost, eliminate the adverse effect of salt impact on a biochemical system and a water ecological environment of a sewage plant, and are suitable for the fields of upgrading and emergency reconstruction of the sewage plant, groundwater remediation of rivers and lakes, mine water purification and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and in particular relates to a deep denitrification system and method for efficient recycling of high-nitrogen desorption liquid. Background Art

[0002] Nitrogen, specifically including ammonia nitrogen and nitrate nitrogen, is a core pollution indicator monitored for water environmental protection. Exceeding the standard range can easily trigger eutrophication, leading to serious ecological disasters. In recent years, with the continuous upgrading and strengthening of my country's environmental protection goals, the demand for deep denitrification technology has become increasingly prominent. For example, due to rapid urbanization and stricter pollutant control standards, many older urban sewage treatment plants are in need of upgrading, most importantly increasing denitrification rates. Urban sewage treatment plants in northern China are prone to excessive nitrogen levels in their effluent due to low winter temperatures, which reduces microbial activity. Lax management of rural domestic and aquaculture wastewater can easily lead to excessive nitrogen levels in rivers, which can, in severe cases, result in black and odorous water bodies. The reuse of coal mine water for landscaping irrigation and dust control is also often limited by nitrogen control standards. A common feature of these practical cases is the need for deep denitrification in water bodies with low nitrogen concentrations. For the two most common types of inorganic nitrogen, ammonia nitrogen and nitrate nitrogen, in emergency situations, ammonia nitrogen can be converted into nitrogen gas through a simple sodium hypochlorite oxidation method to achieve complete mineralization. However, there is currently no popular and efficient and economical physicochemical mineralization technology for nitrate nitrogen, and it can only rely on denitrifying microorganisms for biochemical treatment. Therefore, it is necessary to develop deep removal technology and emergency processes for nitrate nitrogen.

[0003] Ion exchange resins are a mature engineering method for deep removal of nitrate nitrogen. This process transfers nitrate nitrogen from the target water body to a high-nitrogen desorption solution and rinse water. High-nitrogen desorption solutions often have sodium chloride concentrations of tens of thousands to hundreds of thousands of ppm and nitrate nitrogen of hundreds to thousands of ppm, while rinse water often has sodium chloride concentrations of thousands and nitrate nitrogen of tens of ppm. In existing related patents, such as CN 117088538A, CN 116022885A, CN 211078800U, and CN110066076A, high-nitrogen desorption solutions and rinse water are often mixed and discharged into a denitrification system for treatment, and ultimately discharged directly into the aquatic ecosystem. The disadvantage of this approach is that the regeneration solution containing highly concentrated sodium chloride is used once, which is not only costly and cumbersome to dissolve salt, but also releases a large amount of salt into the ecological environment, which can easily cause local salinization. Improved solutions such as CN 115286175 A, CN 108314269 A, CN 108585344A, etc., propose to use nanofiltration-reverse osmosis, electrolysis and other methods to recover sodium chloride salts, but the investment and operating costs are relatively high, and the actual operability is low. A major reason why many scholars did not consider returning the high-nitrogen desorption liquid to resin desorption after denitrification treatment in the denitrification system is that it is often enriched with high concentrations (hundreds to thousands of ppm) of sulfate ions. Since denitrification resins are often strong base chloride-type anion exchange resins, the exchange order of anions is as follows: If the desorption liquid containing sulfate is directly recycled, the groups on the resin will be more combined with sulfate, and eventually the ability to exchange nitrate nitrogen will be lost. On the other hand, in the existing ion exchange resin denitrification projects, resin regeneration mostly adopts high sodium chloride concentration (>6%) to ensure regeneration efficiency, but it is limited by the difficulty in quickly screening and cultivating microbial flora suitable for direct and efficient denitrification under such salinity conditions, resulting in the high-nitrogen desorption liquid having to be mixed with cleaning water or other wastewater to dilute the salt before treatment. The purpose of the present invention is to provide an effective treatment process to remove nitrate nitrogen, sulfate and carbonate / bicarbonate in the high-nitrogen desorption liquid, realize their efficient recycling, and thus construct an economical and efficient deep denitrification system and method on this basis. Summary of the Invention

[0004] The Summary of the Invention introduces a series of simplified concepts that will be further described in the Detailed Description of the Invention. The Summary of the Invention is not intended to limit the key features and essential features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0005] In response to the problem that the high-nitrogen desorption liquid in the existing ion exchange resin deep denitrification technology cannot be recycled, the present invention provides a deep denitrification system and method for the efficient recycling of high-nitrogen desorption liquid. The high-nitrogen desorption liquid and the washing water are treated separately, and the sulfate, nitrate nitrogen and carbonate / bicarbonate in the high-nitrogen desorption liquid are removed by an efficient precipitation system and a high-salt denitrification system, respectively, to obtain a high-salt regeneration liquid with a high sodium chloride purity, which can be recycled for desorption and regeneration of the resin system. In addition, unlike the previous denitrification resin desorption and regeneration mode, which mostly adopts a high sodium chloride concentration (>6%) and a small desorption volume (<5BV), the present invention adopts a low sodium chloride concentration (2% to 6%) and a large desorption volume (5 to 15BV) mode. By increasing the desorption volume, the resin regeneration efficiency is ensured, and at the same time, the salt conditions of the high-nitrogen desorption liquid can be adapted to the conventional high-salt denitrification system, and high-salt denitrification can be directly carried out without dilution.

[0006] To achieve the above objectives, the present invention proposes a deep denitrification system for efficient recycling of high-nitrogen desorption liquid, comprising:

[0007] Filtration system, used to remove particulate matter and suspended solids from denitrification influent, cleaning influent and high-salt regeneration liquid from high-salt denitrification system effluent to avoid resin clogging;

[0008] The resin system is connected to the filtration system and is equipped with a denitrification resin for adsorbing and denitrifying the denitrified influent to achieve the total nitrogen standard in the effluent;

[0009] a desorption liquid tank connected to the resin system and used to contain the high nitrogen desorption liquid discharged during the desorption process of the resin system;

[0010] A cleaning water tank connected to the resin system and used to contain cleaning water discharged during the cleaning process of the resin system;

[0011] An efficient precipitation system, connected to the desorption liquid tank, is used for primary treatment of the high-nitrogen desorption liquid by adding barium material to remove sulfate ions therein;

[0012] A high-salt denitrification system is connected to the high-efficiency precipitation system and is used for secondary treatment of the high-nitrogen desorption liquid. The nitrate nitrogen therein is removed through a high-salt denitrification process, and then the carbonate and / or bicarbonate ions are removed by adding hydrochloric acid to adjust the pH, thereby obtaining a high-salt regeneration liquid with a high sodium chloride purity.

[0013] The high-salt regeneration liquid effluent from the high-salt denitrification system is treated by a filtration system and then recycled for desorption in the resin system.

[0014] Preferably, the denitrification resin is a strong base chloride type anion exchange resin.

[0015] The present invention also proposes a deep denitrification method for achieving efficient recycling of high-nitrogen desorption liquid based on the above-mentioned deep denitrification system, comprising the following steps:

[0016] S1. Resin system adsorption: The denitrification influent is filtered through a filtration system to remove particulate matter and suspended solids. It then passes through fresh or regenerated denitrification resin at a constant flow rate within the resin system to remove nitrate nitrogen, and the denitrification effluent meets the standards.

[0017] S2. Resin system desorption: After the denitrification resin adsorption is complete, the water in the resin column is drained. The high-salt regeneration liquid passes through the filtration system to remove particulate matter and suspended solids. It then passes through the resin at a constant flow rate within the resin system to desorb the nitrate nitrogen on the resin, forming a high-nitrogen desorption liquid that is discharged into the desorption liquid tank.

[0018] S3. Resin system cleaning: After denitrification resin desorption is complete, the high-nitrogen desorption liquid in the resin column is drained. The wash water passes through a filtration system to remove particulate matter and suspended solids. The water then flows through the resin system at a constant flow rate to clean the resin. The resulting wash water is then discharged into a wash water tank and subsequently into the sewage treatment system. The cleaned resin can be reused for adsorption and denitrification, completing an adsorption-desorption-cleaning cycle.

[0019] S4. High-efficiency precipitation treatment: The high-nitrogen desorption liquid in the desorption liquid tank is discharged into a high-efficiency precipitation system, where barium and polyacrylamide (PAM) are added to remove sulfate ions in the form of barium sulfate precipitation.

[0020] S5. High-salt denitrification treatment: The effluent from the efficient sedimentation treatment is discharged into the high-salt denitrification system. By adding carbon source and hydrochloric acid, the cultured salt-tolerant denitrifying microorganisms convert nitrate nitrogen into nitrogen gas or nitrous oxide, thus achieving complete mineralization of nitrate nitrogen. Hydrochloric acid is then added to the denitrification effluent to adjust the pH and remove carbonate / bicarbonate ions, forming a high-salt regeneration liquid with a higher sodium chloride purity, which can be recycled for desorption in the resin system.

[0021] Preferably, in the resin system adsorption in step S1, the denitrification resin is a strong base chloride type anion exchange resin, and the adsorption flow rate is controlled to be 1 to 20 BV / h (BV refers to double bed volume).

[0022] Preferably, in the resin system desorption in step S2, the sodium chloride concentration in the high-salt regeneration liquid is 2% to 6%, the desorption flow rate is controlled to be 0.5 to 5 BV / h, and the desorption liquid volume is controlled to be 5 to 15 BV.

[0023] Preferably, in the resin system cleaning step S3, the cleaning flow rate is controlled to be 0.5-5BV / h, and the cleaning water volume is controlled to be 2-10BV; the cleaning water is discharged into the sewage treatment system in the form of directly discharging into the biochemical regulating tank of the sewage treatment plant or into the urban sewer.

[0024] Preferably, in the efficient precipitation treatment in step S4, the barium material includes one or a mixture of barium chloride, barium hydroxide, barium nitrate, barium carbonate, and barium acetate.

[0025] Preferably, in the high-salt denitrification treatment in step S5, the form of the high-salt denitrification system includes but is not limited to a membrane bioreactor (MBR), a sequencing batch sludge tank (SBR), an activated sludge tank + a secondary sedimentation tank, or a biofilm tank + a secondary sedimentation tank; the carbon source is one or a combination of alcohols, carboxylates, carboxylic acids, sugars, sludge hydrolysis supernatant, landfill leachate, and domestic sewage; and hydrochloric acid is added to the denitrification effluent to adjust the pH to 3.0-5.0.

[0026] The beneficial effects achieved by the present invention are as follows:

[0027] (1) The deep denitrification system and method constructed by the present invention can purify the high-nitrogen desorption liquid generated in the desorption process of the ion exchange denitrification resin into a high-salt regeneration liquid with a higher sodium chloride purity through an efficient precipitation system and a high-salt denitrification system. The high-nitrogen desorption liquid can be recycled for the desorption and regeneration of the denitrification resin, greatly reducing the sodium chloride salt consumption and saving operating costs, and eliminating the heavy labor burden brought by the salt dissolution process.

[0028] (2) The deep denitrification system and method constructed by the present invention greatly reduces the discharge of waste brine through the efficient recycling of high-nitrogen desorption liquid, eliminating the adverse effects of salt shock on the biochemical system and water ecological environment of the sewage treatment plant.

[0029] (3) The deep denitrification system and method constructed by the present invention places the high-efficiency precipitation system for removing sulfate at the front end of high-salt denitrification, ensuring that there is no sulfate in the high-salt denitrification influent, avoiding the cultivation of sulfate-reducing bacteria to compete with denitrifying bacteria for carbon sources, and improving the effective utilization rate of carbon sources.

[0030] (4) The deep denitrification system and method constructed by the present invention can support the denitrification resin regeneration process using a low sodium chloride concentration (2% to 6%) and a large desorption volume (5 to 15BV) mode due to the efficient recycling of high-nitrogen desorption liquid. While ensuring the resin regeneration efficiency, it is adapted to the conventional high-salt denitrification system, avoiding the phenomenon of nitrate nitrogen being easily reduced to ammonia nitrogen in the denitrification process under excessively high sodium chloride concentrations (>6%), thereby ensuring a higher nitrate mineralization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are used to further explain the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0032] Figure 1 This is a roadmap for a deep denitrification system and method for efficient recycling of high-nitrogen desorption liquid in the present invention.

[0033] Figure 2 The deep denitrification system provided by the present invention is used as a roadmap for sewage treatment plant upgrading and emergency transformation.

[0034] Figure 3 A roadmap for the deep denitrification system provided by the present invention for the restoration of polluted rivers.

[0035] Figure 4 A roadmap for the deep denitrification system provided by the present invention for mine water purification. DETAILED DESCRIPTION

[0036] The present invention will be described and explained in detail below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0037] Example 1:

[0038] Figure 1 A deep denitrification system with efficient recycling of high-nitrogen desorption liquid was demonstrated, including a filtration system, a resin system, a desorption liquid tank, a cleaning water tank, an efficient precipitation system, and a high-salt denitrification system.

[0039] The filtration system is used to remove particulate matter and suspended matter in the denitrification influent, cleaning influent and high-salt regeneration liquid of the high-salt denitrification system effluent to avoid resin clogging; the resin system is connected to the filtration system and is equipped with a denitrification resin for adsorption and denitrification treatment of the denitrification influent to achieve the total nitrogen standard of the effluent; the desorption liquid tank is connected to the resin system and is used to hold the high-nitrogen desorption liquid discharged during the desorption process of the resin system; the cleaning water tank is connected to the resin system and is used to hold the cleaning water discharged during the cleaning process of the resin system; the high An efficient precipitation system is connected to the desorption liquid tank and is used for primary treatment of the high-nitrogen desorption liquid, removing sulfate therein by adding barium material; a high-salt denitrification system is connected to the efficient precipitation system and is used for secondary treatment of the high-nitrogen desorption liquid, removing nitrate nitrogen therein by a high-salt denitrification process, and then removing carbonate and / or bicarbonate by adding hydrochloric acid to adjust the pH, thereby obtaining a high-salt regeneration liquid with a higher sodium chloride purity; wherein the high-salt regeneration liquid effluent from the high-salt denitrification system is treated by the filtration system and then recycled for desorption in the resin system.

[0040] Example 2:

[0041] Figure 2 The display is based on Figure 1The deep denitrification system is used as a roadmap for sewage treatment plant upgrading and emergency renovation. Taking a certain urban sewage treatment plant in Yancheng City, Jiangsu Province as an example, the effluent from this urban sewage treatment plant currently complies with Standard A in Table 1 of the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants" (DB32 / 4440-2022), which requires total nitrogen to be less than 10 mg / L. The current average total nitrogen concentration is 7-8 mg / L. The urban sewage treatment plant plans to upgrade its effluent to less than 2 mg / L after the renovation, meeting the Class V water requirements in the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0042] The processing steps are as follows:

[0043] S1. Resin system adsorption: Denitrification influent (effluent from the high-density sedimentation tank of a municipal sewage treatment plant) is filtered to remove particulate matter and suspended solids. It then passes through fresh or regenerated denitrification resin at a flow rate of 5 BV / h to remove nitrate nitrogen. The denitrified effluent, which meets the standards, is then discharged to the discharge pond.

[0044] S2. Resin System Desorption: After the denitrification resin adsorption is complete, the water in the resin column is drained. 8 BV of high-salt regeneration solution (4% sodium chloride concentration) is filtered to remove particulate matter and suspended solids. The solution is then passed through the resin at a rate of 1 BV / h to desorb nitrate nitrogen from the resin, forming a high-nitrogen desorption solution that is discharged to the desorption tank.

[0045] S3. Resin System Cleaning: After denitrification resin desorption is complete, the high-nitrogen desorption liquid in the resin column is drained. 4 BV of wash influent (effluent from the high-density sedimentation tank of a municipal sewage treatment plant) is filtered to remove particulate matter and suspended solids. The water then flows through the resin system at a flow rate of 1 BV / h for cleaning. The resulting wash effluent is discharged to the wash water tank and then to the sewage treatment plant's biochemical conditioning tank. The cleaned resin can be reused for adsorption and denitrification, completing an adsorption-desorption-cleaning cycle.

[0046] S4. High-efficiency precipitation treatment: The high-nitrogen desorption liquid in the desorption tank is discharged into a high-efficiency precipitation system, where barium chloride and polyacrylamide (PAM) are added to remove sulfate ions in the form of barium sulfate precipitation.

[0047] S5. High-salt denitrification treatment: The effluent from the efficient sedimentation treatment is discharged into the high-salt denitrification system. By adding carbon source and hydrochloric acid, the cultured salt-tolerant denitrifying microorganisms convert nitrate nitrogen into nitrogen gas or nitrous oxide, thus achieving complete mineralization of nitrate nitrogen. Hydrochloric acid is then added to the denitrification effluent to adjust the pH to 4.0, remove carbonate / bicarbonate ions, and form a high-salt regeneration liquid with higher sodium chloride purity, which can be recycled for desorption in the resin system.

[0048] The above experimental operation was repeated eight times using a pilot plant, and the treatment effect was verified as shown in Table 1. The experimental results show that the high-salt regeneration liquid after the high-nitrogen desorption liquid was treated sequentially by the high-efficiency precipitation system and the high-salt denitrification system can be recycled for desorption by the denitrification resin, and the effect is basically stable after the fifth desorption.

[0049] Table 1 Treatment effect of deep denitrification system used for sewage treatment plant upgrading and emergency transformation verification

[0050]

[0051]

[0052] Example 3:

[0053] Figure 3 The display is based on Figure 1 The deep denitrification system is used as a roadmap for remediating polluted rivers. For example, a polluted river in Nantong City, Jiangsu Province, has a total nitrogen concentration of 4-5 mg / L, of which over 90% is nitrate nitrogen. The requirement is that after treatment, the total nitrogen concentration be less than 1.5 mg / L, meeting the Class IV water requirements of the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0054] The processing steps are as follows:

[0055] S1. Resin system adsorption: Denitrification influent (polluted river water) is filtered to remove particulate matter and suspended solids. It then passes through fresh or regenerated denitrification resin at a flow rate of 10 BV / h to remove nitrate nitrogen. The denitrified effluent, which meets the standards, is then discharged to the downstream river.

[0056] S2. Resin System Desorption: After the denitrification resin adsorption is complete, the water in the resin column is drained. 6 BV of high-salt regeneration solution (5% sodium chloride concentration) is filtered to remove particulate matter and suspended solids. The solution is then passed through the resin system at a rate of 1 BV / h to desorb nitrate nitrogen from the resin, forming a high-nitrogen desorption solution that is discharged to the desorption liquid tank.

[0057] S3. Resin System Cleaning: After denitrification resin desorption is complete, the high-nitrogen desorption liquid in the resin column is drained. 3 BV of wash water (tap water) is filtered through a filtration system to remove particulate matter and suspended solids. The water then flows through the resin system at a flow rate of 1 BV / h for cleaning. The resulting wash water is discharged into a wash water tank and subsequently into the town sewer. The cleaned resin can be reused for adsorption and denitrification, completing an adsorption-desorption-cleaning cycle.

[0058] S4. High-efficiency precipitation treatment: The high-nitrogen desorption liquid in the desorption tank is discharged into a high-efficiency precipitation system, where barium chloride and polyacrylamide (PAM) are added to remove sulfate ions in the form of barium sulfate precipitation.

[0059] S5. High-salt denitrification treatment: The effluent from the efficient sedimentation treatment is discharged into the high-salt denitrification system. By adding carbon source and hydrochloric acid, the cultured salt-tolerant denitrifying microorganisms convert nitrate nitrogen into nitrogen gas or nitrous oxide, thus achieving complete mineralization of nitrate nitrogen. Hydrochloric acid is then added to the denitrification effluent to adjust the pH to 4.0, remove carbonate / bicarbonate ions, and form a high-salt regeneration liquid with higher sodium chloride purity, which can be recycled for desorption in the resin system.

[0060] The above experimental operation was repeated six times using a pilot plant, and the treatment effect was verified as shown in Table 2. The experimental results show that the high-salt regeneration liquid after the high-nitrogen desorption liquid was treated sequentially by the high-efficiency precipitation system and the high-salt denitrification system can be recycled for desorption by the denitrification resin, and the effect is basically stable after the fourth desorption.

[0061] Table 2 Verification of treatment effect of deep denitrification system for remediation of polluted rivers

[0062]

[0063] Example 4:

[0064] Figure 4 The display is based on Figure 1 The roadmap for using the deep denitrification system for mine water purification is presented. Taking the mine water from a coal mine in Ordos City, Inner Mongolia, as an example, the total nitrogen concentration in this mine water is approximately 3 mg / L, of which more than 80% is nitrate nitrogen. The requirement for the treated water is to be below 1.0 mg / L, meeting the Class III water requirements of the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0065] The processing steps are as follows:

[0066] S1. Resin system adsorption: Denitrification influent (mine water) is filtered to remove particulate matter and suspended solids. It then passes through fresh or regenerated denitrification resin at a flow rate of 15 BV / h to remove nitrate nitrogen. The denitrification effluent that meets the standards is then discharged to the purification pool.

[0067] S2. Resin system desorption: After the denitrification resin adsorption is complete, the water in the resin column is drained; 9 BV of high-salt regeneration liquid (4% sodium chloride concentration) is filtered to remove particulate matter and suspended solids. The liquid is then passed through the resin system at a rate of 1.5 BV / h to desorb nitrate nitrogen from the resin, forming a high-nitrogen desorption liquid that is discharged to the desorption liquid tank;

[0068] S3. Resin System Cleaning: After denitrification resin desorption is complete, the high-nitrogen desorption liquid in the resin column is drained. 4 BV of wash water (mine water) is filtered through a filtration system to remove particulate matter and suspended solids. It then passes through the resin system at a flow rate of 1 BV / h for cleaning. The resulting wash water is discharged into a wash water tank and subsequently into the town sewer. The cleaned resin can be reused for adsorption and denitrification, completing an adsorption-desorption-cleaning cycle.

[0069] S4. High-efficiency precipitation treatment: The high-nitrogen desorption liquid in the desorption liquid tank is discharged into a high-efficiency precipitation system, where barium hydroxide and polyacrylamide (PAM) are added to remove sulfate ions in the form of barium sulfate precipitation.

[0070] S5. High-salt denitrification treatment: The effluent from the efficient sedimentation treatment is discharged into the high-salt denitrification system. By adding carbon source and hydrochloric acid, the cultured salt-tolerant denitrifying microorganisms convert nitrate nitrogen into nitrogen gas or nitrous oxide, thus achieving complete mineralization of nitrate nitrogen. Hydrochloric acid is then added to the denitrification effluent to adjust the pH to 4.0, remove carbonate / bicarbonate ions, and form a high-salt regeneration liquid with higher sodium chloride purity, which can be recycled for desorption in the resin system.

[0071] The above experimental operation was repeated six times using a pilot plant, and the treatment effect was verified as shown in Table 3. The experimental results show that the high-salt regeneration liquid after the high-nitrogen desorption liquid was treated sequentially by the high-efficiency precipitation system and the high-salt denitrification system can be recycled for desorption by the denitrification resin, and the effect is basically stable after the fourth desorption.

[0072] Table 3 Verification of treatment effect of deep denitrification system for mine water purification

[0073]

[0074] Finally, it should be noted that the above-described embodiments merely represent several implementation methods of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made by a person skilled in the art without departing from the spirit of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention should be based on the appended claims.

Claims

1. A deep denitrification system with efficient recycling of high-nitrogen desorption liquid, characterized in that: include: Filtration system, used to remove particulate matter and suspended solids from denitrification influent, cleaning influent and high-salt regeneration liquid from high-salt denitrification system effluent; A resin system connected to the filtration system, equipped with a denitrification resin for performing adsorption denitrification treatment on the denitrification influent; a desorption liquid tank connected to the resin system and used to contain the high nitrogen desorption liquid discharged during the desorption process of the resin system; A cleaning water tank connected to the resin system and used to contain cleaning water discharged during the cleaning process of the resin system; An efficient precipitation system, connected to the desorption liquid tank, is used for primary treatment of the high-nitrogen desorption liquid by adding barium material to remove sulfate ions therein; A high-salt denitrification system is connected to the high-efficiency precipitation system and is used for secondary treatment of the high-nitrogen desorption liquid. The nitrate nitrogen therein is removed through a high-salt denitrification process, and then the carbonate and / or bicarbonate are removed by adding hydrochloric acid to adjust the pH to obtain a high-salt regeneration liquid. The high-salt regeneration liquid effluent from the high-salt denitrification system is treated by a filtration system and then recycled for desorption in the resin system.

2. The deep denitrification system according to claim 1, characterized in that: The denitrification resin is a strong base chloride type anion exchange resin.

3. A deep denitrification method for realizing efficient recycling of high-nitrogen desorption liquid based on the deep denitrification system according to claim 1, characterized in that: The following steps are involved: S1. Resin system adsorption: The denitrification influent is filtered to remove particulate matter and suspended solids, and then the resin system adsorbs nitrate nitrogen, and discharges denitrification effluent that meets the standards. S2. Resin system desorption: The high-salt regeneration liquid is filtered to remove particulate matter and suspended solids, and the nitrate nitrogen on the resin in the resin system is desorbed to form a high-nitrogen desorption liquid and discharged to the desorption liquid tank; S3. Resin system cleaning: The cleaning water is filtered through a filtration system to remove particulate matter and suspended solids, cleans the resin in the resin system, and forms cleaning water that is discharged into a cleaning water tank and then into a sewage treatment system. S4. High-efficiency precipitation treatment: The high-nitrogen desorption liquid in the desorption liquid tank is discharged into a high-efficiency precipitation system, where barium and polyacrylamide are added to remove sulfate ions in the form of barium sulfate precipitation. S5. High-salt denitrification treatment: The effluent from the efficient sedimentation treatment is discharged into the high-salt denitrification system, where denitrification and denitrification are carried out by adding a carbon source. Hydrochloric acid is then added to the denitrification effluent to adjust the pH, forming a high-salt regeneration liquid which is recycled for desorption in the resin system.

4. The deep denitrification method according to claim 3, characterized in that In the resin system adsorption in step S1, the adsorption flow rate is 1 to 20 BV / h.

5. The deep denitrification method according to claim 3, characterized in that In the resin system desorption in step S2, the sodium chloride concentration in the high-salt regeneration liquid is 2% to 6%, the desorption flow rate is 0.5 to 5 BV / h, and the desorption liquid volume is controlled to be 5 to 15 BV.

6. The deep denitrification method according to claim 3, characterized in that: In the resin system cleaning in step S3, the cleaning flow rate is controlled to 0.5-5 BV / h, and the cleaning water volume is controlled to 2-10 BV; the cleaned resin can be reused for adsorption and denitrification to achieve an adsorption-desorption-cleaning cycle; the cleaning water is discharged into the sewage treatment system in the form of direct discharge into the sewage treatment plant biochemical regulating tank or into the urban sewer.

7. The deep denitrification method according to claim 3, characterized in that: In the efficient precipitation treatment in step S4, the barium material is one or a mixture of barium chloride, barium hydroxide, barium nitrate, barium carbonate, and barium acetate.

8. The deep denitrification method according to claim 3, characterized in that: In the high-salt denitrification treatment in step S5, the high-salt denitrification system includes a membrane bioreactor, a sequencing batch sludge tank, an activated sludge tank + a secondary sedimentation tank, or a biofilm tank + a secondary sedimentation tank.

9. The deep denitrification method according to claim 3, characterized in that: In the high-salt denitrification treatment of step S5, the carbon source is one or a combination of alcohols, carboxylates, carboxylic acids, sugars, sludge hydrolysis supernatant, landfill leachate, and domestic sewage.

10. The deep denitrification method according to claim 3, characterized in that: In the high-salt denitrification treatment of step S5, hydrochloric acid is added to the denitrification effluent to adjust the pH to 3.0-5.0.

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