Method for denitrification of high-salt and high-nitrate nitrogen wastewater

Abstract

The application provides a high-salt and high-nitrate nitrogen wastewater denitrification method, which comprises the following steps: S1, adjusting the pH of the high-salt and high-nitrate nitrogen wastewater to the range of 5.5-7.5, and adopting a primary full-mixed denitrification tank for denitrification, wherein a composite microbial inoculum is put into the primary full-mixed denitrification tank at one time, and the composite microbial inoculum comprises Marinobacter, Azoarcus, Paracoccus, Bacillus and Pseudomonas; S2, adopting a secondary full-mixed denitrification tank for denitrification of the effluent of step S1; during the operation of the secondary full-mixed denitrification tank, a mud-water mixture is backflowed to the primary full-mixed denitrification tank; S3, the effluent of step S2 is introduced into a degassing tank for degassing; S4, the effluent of step S3 is precipitated in a precipitation tank, and then the effluent is discharged. The composite microbial inoculum is used for treating the high-salt and high-nitrate nitrogen wastewater, and the problems of large treatment facility area and high cost caused by concentrated evaporation or dilution of wastewater and then biochemical treatment in traditional treatment are avoided.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of sewage treatment, in particular to a high-salt high-nitrate-nitrogen wastewater denitrification method. BACKGROUND

[0002] High-salt wastewater refers to wastewater with a total salt content of at least 1%, including high-salt industrial wastewater and high-salt domestic wastewater. High-salt wastewater has a wide source and an increasing water volume year by year. It mainly comes from industrial production, domestic water, and production processes of pharmaceuticals, chemicals, food processing, fuels, and oil and natural gas collection and processing. With the problem of eutrophication caused by excessive nitrogen and phosphorus in wastewater, wastewater denitrification has attracted more and more attention. Nitrogen pollutants in wastewater have gradually replaced traditional organic pollutants to become the primary goal of water pollution prevention and control. Ion exchange is a classic and efficient ion removal technology, which is widely used in industrial applications. The ion exchange resin denitrification process applied to wastewater advanced treatment not only has low total nitrogen (TN) content in the effluent, but also can remove part of total phosphorus, COD, suspended solids (SS), and can realize the recycling of the resin through resin regeneration. The regenerated waste liquid contains high-concentration sodium chloride and nitrate and cannot be directly discharged. It must be denitrified and discharged after reaching the standard. A large amount of inorganic salt ions such as Na + , Ca 2+ , Cl - , SO4 2- in high-salt wastewater seriously affect the biological purification effect of the wastewater treatment system, and are one of the most difficult wastewater to treat. The treatment process of high-salt wastewater mainly includes physical, chemical and biological methods. The treatment by the physicochemical method is high in cost and difficult to achieve the expected purification effect. At present, the treatment of high-salt high-nitrogen wastewater mostly adopts the method of concentration and evaporation, but due to the problems of high investment and operation cost, complex management and the like, it is difficult to be applied on a large scale.

[0003] The biological denitrification process is the most economical and effective denitrification technology. In this process, nitrate is used as the only nitrogen source and electron acceptor, and the final product is gaseous nitrogen under the metabolic activity of denitrifying bacteria. However, under normal circumstances, the salt tolerance of the biological denitrification process is generally below 1%, and high salt concentration will cause problems such as separation of bacteria from the cell wall, inactivation and even death of the cells, which greatly limits the application of the technology in the field of high-salt wastewater. Moreover, nitrite produced in the denitrification process competes with nitrate for electron donors, and the promotion of salt-tolerant bacteria to the denitrification process mainly lies in promoting the activity of nitrate reductase, thereby accelerating the conversion of nitrate to nitrite and improving the total nitrogen removal rate. Adding microbial agents to the activated sludge system can improve the degradation efficiency of pollutants by affecting the microbial community structure. SUMMARY

[0004] 1. Problems to be solved

[0005] In view of the problem that the existing high-salt and high-nitrate nitrogen wastewater cannot be treated by a biochemical method, the application provides a high-salt and high-nitrate nitrogen wastewater denitrification method.

[0006] 2. Technical solution

[0007] In order to solve the above problems, the technical scheme adopted by the application is as follows:

[0008] The application provides a high-salt and high-nitrate nitrogen wastewater denitrification method, the salt concentration of the high-salt and high-nitrate nitrogen wastewater is between 6000 and 40000 mg / L, and the nitrate nitrogen concentration is between 300 and 1000 mg / L; the method comprises the following steps:

[0009] S1 adjusts the pH of the high-salt and high-nitrate nitrogen wastewater to be within the range of 5.5 to 7.5, and denitrification is performed by using a primary full-mix denitrification tank, the primary full-mix denitrification tank is provided with a composite microbial inoculant, the composite microbial inoculant comprises Marinobacter, and further comprises Azoarcus, Paracoccus, Bacillus and Pseudomonas; the functional bacteria used in the application are denitrifying functional bacteria existing in a marine environment; the composite inoculant is resistant to high salt and has good denitrification performance; the start is rapid and convenient, and the effect is rapidly generated after addition; the temperature adaptability is strong, and the effect is good at 2 to 45 DEG C;

[0010] S2 performs denitrification on the effluent of step S1 by using a secondary full-mix denitrification tank; the secondary full-mix denitrification tank is provided with a mud-water mixture backflow to the primary full-mix denitrification tank during operation;

[0011] S3 the effluent of step S2 enters a degassing tank for degassing; for example, the degassing is performed in a way of air blowing and stirring; in the application, the degassing tank is added after the denitrification tank, because under the high-salt condition, the flocculation effect of the microorganism is poor, and due to the increase of the specific gravity of the water, the active sludge is lost due to the nitrogen gas generated by the system denitrification, which affects the mud-water separation effect of the subsequent sedimentation tank, and the addition of the degassing tank can solve this problem;

[0012] S4 the effluent of step S3 is precipitated by a sedimentation tank, or a deep treatment is supplemented, when the water load changes too much or the water concentration exceeds the design standard, the effluent will be out of standard, and the effluent is treated by nanofiltration after precipitation in the sedimentation tank.

[0013] As the preferred embodiment of any of the technical solutions of the first aspect of the present application, the percentage of Marinobacter in the compound microbial inoculant in step S1 is 30% to 40%. If the percentage of Marinobacter is too high, it will easily cause the accumulation of nitrite nitrogen, and if it is too low, it will affect the nitrogen degradation efficiency; the Marinobacter cooperates with other complete denitrification bacteria to play a synergistic role, and more preferably, the mass percentage of Marinobacter in the compound microbial inoculant in step S1 is 30% to 40%, the mass percentage of Azotobacter is 20% to 30%, the mass percentage of Paracoccus is 20% to 30%, the mass percentage of Bacillus is 5% to 10%, and the mass percentage of Pseudomonas is 10% to 20%.

[0014] As the preferred embodiment of any of the technical solutions of the first aspect of the present application, the Marinobacter in step S1 includes one or both of Marinobacter hydrocarbonoclasticus or Marinobacterium Nitratireducens;

[0015] The Azoarcus in step S1 includes Azoarcus Indigens;

[0016] The Paracoccus in step S1 includes Paracoccus Denitrificans;

[0017] The Bacillus in step S1 includes Bacillus Azotoformans;

[0018] The Pseudomonas in step S1 includes Pseudomonas Stutzeri.

[0019] As the preferred embodiment of any of the technical solutions of the first aspect of the present application, the dosage ratio of the mass of the compound inoculant to the total volume of the reactor in step S1 is 0.1 ‰ to 0.5 ‰, and the mass of the compound inoculant is the dry weight of the compound inoculant. The compound microbial inoculant of the present application can promote the growth of dominant bacteria under the condition of high salt and high nitrite nitrogen, increase the abundance of the bacteria, and become a dominant species, thereby improving the denitrification capacity of the overall biochemical system. The above-mentioned salt-tolerant denitrifying bacteria are compounded to improve the salt tolerance of the system and rapidly and efficiently remove nitrogen.

[0020] As the preferred embodiment of any of the technical solutions of the first aspect of the present application, in step S1, the pH of the high-salt high-nitrite nitrogen wastewater is adjusted to a range of 6.0 to 7.0.

[0021] As a preferred embodiment of any of the technical solutions of the first aspect of the present application, in step S2, the reflux ratio of the sludge-water mixture from the secondary full-mix denitrification tank to the primary full-mix denitrification tank is 25% to 50%. In the present application, the secondary full-mix denitrification tank is refluxed to the primary full-mix denitrification tank, which aims to prolong the residence time, strengthen the treatment, and at the same time, make efficient use of the carbon source, improve the treatment effect, and have strong resistance to impact load.

[0022] As a preferred embodiment of any of the technical solutions of the first aspect of the present application, the carbon source added in the primary full-mix denitrification tank contains acetic acid and glucose. The acetic acid can accelerate the denitrification rate, and the glucose is a conventional nutrient. The configuration purpose is to first accelerate the activation of microbial inoculum and promote the rapid reproduction of denitrifying heterotrophic bacteria, thereby improving the utilization rate of microorganisms; and secondly, the denitrification consumes hydrogen ions, and the addition of acetic acid can appropriately adjust the reaction pH.

[0023] As a preferred embodiment of any of the technical solutions of the first aspect of the present application, the C:N in the primary full-mix denitrification tank is controlled to be between 2 to 4:1. The carbon-nitrogen ratio is lower than that of the conventional method, and will not cause the COD breakthrough problem.

[0024] As a preferred embodiment of any of the technical solutions of the first aspect of the present application, the sludge in the sedimentation tank is refluxed to the primary full-mix denitrification tank, and the sludge concentration in the primary full-mix denitrification tank is controlled to be 4 to 6 g / L. The purpose of refluxing the sludge is that the microorganisms in the sludge proliferate rapidly under the stimulation of the salt content and concentration of the influent water, and the mixed bacteria are gradually eliminated; the amount of refluxed sludge, i.e., the amount of microorganisms, is controlled, and a certain amount of microorganisms (especially dominant bacteria) are enriched to better treat nitrate nitrogen.

[0025] As a preferred embodiment of any of the technical solutions of the first aspect of the present application, the residual sludge in the sedimentation tank is discharged to a sludge thickening tank.

[0026] As a preferred embodiment of any of the technical solutions of the first aspect of the present application, the residence time of the high-salt high-nitrate nitrogen wastewater in the primary full-mix denitrification tank and the secondary full-mix denitrification tank is greater than 6 h.

[0027] As a preferred embodiment of any of the technical solutions of the first aspect of the present application, the nanofiltration membrane in step S4 includes a roll-type nanofiltration membrane assembly, which is an integrated device. The membrane material is polyamide material, which is used for the advanced treatment of nitrate nitrogen.

[0028] Further, the concentrated water generated by the roll-type nanofiltration membrane assembly is discharged into the influent conditioning tank to adjust the pH in step S1, and the fresh water is discharged into the discharge tank.

[0029] The second aspect of the present application provides a high-salt high-nitrate nitrogen wastewater denitrification system, which comprises, in sequence, an influent conditioning tank, a primary full-mix denitrification tank, a secondary full-mix denitrification tank, a degassing tank, a sedimentation tank, a roll-type nanofiltration membrane assembly, and a discharge tank.

[0030] The preparation tank is used for adjusting the pH of high-salt and high-nitrate nitrogen wastewater;

[0031] The first full-mixing denitrification tank is used for realizing denitrification under high-salt condition by using a composite microbial agent, and the first full-mixing denitrification tank further comprises a carbon source preparation and adding device; preferably, a reflux pipe is arranged between the second full-mixing denitrification tank and the first full-mixing denitrification tank, and the mud-water mixture is refluxed to the first full-mixing denitrification tank during operation of the second full-mixing denitrification tank;

[0032] The degassing tank is provided with an air inlet pipeline for introducing air;

[0033] The sedimentation tank is provided with a sludge discharge pipe for discharging sludge into the first full-mixing denitrification tank and a sludge discharge pipe for discharging sludge into the sludge thickening tank, and the sedimentation tank is further connected to the sludge thickening tank;

[0034] The roll-type nanofiltration membrane assembly is provided with a concentrated water pipe for discharging concentrated water into the water inlet preparation tank.

[0035] As a preferred embodiment of any of the technical solutions of the second aspect of the present application, the roll-type nanofiltration membrane assembly is an integrated device, the membrane material is polyamide material, and the device is used for deep treatment of nitrate nitrogen.

[0036] As a preferred embodiment of any of the technical solutions of the second aspect of the present application, the concentrated water generated by the roll-type nanofiltration membrane assembly is discharged into the water inlet preparation tank, and the fresh water generated is discharged into the discharge tank.

[0037] Compared with the prior art, the present application has the following beneficial effects: the high-salt and high-nitrate nitrogen wastewater denitrification method and system provided by the present application is used for treating high-salt and high-nitrate nitrogen wastewater with a salt concentration of 6000-40000 mg / L and a nitrate nitrogen concentration of 300-1000 mg / L by using a composite microbial agent, the mud-water mixture is refluxed to the first full-mixing denitrification tank during operation of the second full-mixing denitrification tank, thereby overcoming the problem of low treatment efficiency under fluctuating water inflow, a degassing tank is arranged after the second full-mixing denitrification tank, thereby overcoming the problems of sludge floating and sludge loss in the sedimentation tank, and the biochemical method is successfully used for treating high-salt and high-nitrate nitrogen wastewater, thereby avoiding the problems of large treatment facilities, large land occupation, high investment cost, high operation cost, etc. caused by using concentration evaporation or dilution of wastewater for biochemical treatment in traditional high-salt and high-nitrate nitrogen wastewater treatment, and the method of the present application is more economical and efficient. After the high-salt and high-nitrate nitrogen wastewater is treated by the method of the present application, it can be discharged normally, and in the case of large water inflow, the water in the sedimentation tank can be discharged into the roll-type nanofiltration membrane assembly for deep denitrification to ensure the system water quality. By adding the microbial agent and operating parameters of the present application, the existing microbial community structure is improved and strengthened, so that the high-salt and high-nitrate nitrogen wastewater can be directly treated by the biochemical method, compared with the traditional method, the salt tolerance is higher, the nitrate nitrogen concentration is higher, the treatment cost is lower, the effect is faster, and no additional equipment investment is required. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the denitrification system for high-salt, high-nitrate nitrogen wastewater according to Embodiment 1 of the present invention.

[0039] The labels in the diagram represent: 1. Influent mixing tank; 2. Primary mixed-state denitrification tank; 3. Secondary mixed-state denitrification tank; 4. Degassing tank; 5. Sedimentation tank; 6. Spiral wound nanofiltration membrane module; 7. Drainage tank; 8. Sludge thickening tank; 9. Carbon source preparation and dosing device.

[0040] Figure 2 The curves show the total salt concentration, influent nitrate nitrogen concentration, and effluent nitrate nitrogen concentration during the commissioning of Example 5.

[0041] Figure 3 The curves show the total salt concentration, influent total nitrogen concentration, and effluent total nitrogen concentration during the commissioning of Example 5. Detailed Implementation

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0043] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0044] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as “less than about 4.5,” which should be interpreted to include all the aforementioned values ​​and ranges. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0045] The technical solutions of the present application will be described clearly and completely below in connection with specific embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0046] Marinobacter, Azoarcus, Paracoccus, Bacillus and Pseudomonas in the composite microbial agent can be purchased from the market. In the embodiments of the present application, Marinobacter hydrocarbonoclasticus (item number B69399, preservation number ATCC: 49840) is purchased from Ningbo Mingzhou Biotechnology Co., Ltd.; Marinobacterium Nitratireducens (item number bio-03321, preservation number JCM: 15523), Azoarcus Indigens (item number bio-091253, preservation number ATCC: 51398), Paracoccus Denitrificans (item number bio-02824), Bacillus Azotoformans (item number bio-110716, preservation number ATCC 29788) and Pseudomonas Stutzeri (item number bio-83626, preservation number ATCC: 14405) are purchased from the China Microbial Strain Query Network. After being cultured separately, they are mixed and cultured according to the proportion, and then inoculated into the reactor.

[0047] Embodiment 1

[0048] As shown in Figure 1 A denitrification system for high-salt high-nitrate nitrogen wastewater includes, in sequence, a water inlet adjusting pool (1), a first full-mix denitrification pool (2), a second full-mix denitrification pool (3), a degassing pool (4), a sedimentation pool (5), a roll-type nanofiltration membrane assembly (6) and a discharge pool (7). In the wastewater treatment in this embodiment, the roll-type nanofiltration membrane assembly is not used for treatment. When the water inlet load changes too much or the water inlet concentration exceeds the design standard in actual working conditions, the water outlet will exceed the standard, and then the nanofiltration membrane is used for nanofiltration treatment.

[0049] The adjusting pool is used for adjusting the water quality and pH of the high-salt high-nitrate nitrogen wastewater.

[0050] The first-stage full-mixing denitrification tank is used for realizing denitrification under high-salt conditions by using a composite microbial agent, and further comprises a carbon source configuration and adding device; a reflux pipe is arranged between the first-stage full-mixing denitrification tank and the second-stage full-mixing denitrification tank, and the reflux sludge mixture is refluxed into the first-stage full-mixing denitrification tank during operation of the second-stage full-mixing denitrification tank;

[0051] The sedimentation tank is provided with a sludge discharge pipe discharging sludge into the first-stage full-mixing denitrification tank and a sludge discharge pipe of the sludge thickening tank; and the sedimentation tank is further connected to the sludge thickening tank;

[0052] The deaeration tank is provided with an air inlet pipe for introducing air;

[0053] The roll-type nanofiltration membrane assembly is provided with a concentrated water pipe discharging concentrated water into the water inlet adjusting tank, and is an integrated device, the membrane material is polyamide material, and is used for deep treatment of nitrate nitrogen. The concentrated water generated by the roll-type nanofiltration membrane assembly is discharged into the water inlet adjusting tank, and the fresh water generated is discharged into the discharge tank.

[0054] The denitrification method for treating high-salt high-nitrate nitrogen wastewater by using the above system, the treatment tail water denitrification resin desorption liquid, the treatment water volume is 10 tons / day, the salt concentration in the wastewater is about 40000 mg / L, and the nitrate nitrogen concentration is 300 mg / L; the method comprises the following steps:

[0055] S1 adjusts the pH of the high-salt high-nitrate nitrogen wastewater to 6.5-7, and denitrification is performed by using the first-stage full-mixing denitrification tank; the composite microbial agent is added into the first-stage full-mixing denitrification tank at one time, the composition of the composite microbial agent is Marinobacter hydrocarbonoclasticus (product number B69399, preservation number ATCC: 49840), Azoarcus Indigens (product number bio-091253, preservation number ATCC: 51398), Paracoccus Denitrificans (product number bio-02824), Bacillus Azotoformans (product number bio-110716, preservation number ATCC 29788), and Pseudomonas Stutzeri (product number bio-83626, preservation number: ATCC: 14405), and the mixing ratio is 30%:30%:10%:10%:20%; the mass of the composite microbial agent is 0.1‰ of the total volume of the reactor, and the mass of the composite microbial agent is the dry weight of the composite microbial agent; during the treatment, the carbon source, acetic acid and glucose, are added into the first-stage full-mixing denitrification tank, and the C:N in the first-stage full-mixing denitrification tank is kept between 2 and 4:1;

[0056] S2 The effluent from step S1 is subjected to denitrification in a secondary full-mix denitrification tank; during operation of the secondary full-mix denitrification tank, a backflow of mud and water mixture is introduced into the primary full-mix denitrification tank, and the backflow ratio is 30%;

[0057] The total residence time of the primary full-mix denitrification tank and the secondary full-mix denitrification tank is 8 h;

[0058] S3 The effluent from step S2 is introduced into a degassing tank for degassing, and air is blown into the degassing tank for stirring;

[0059] S4 After the effluent from step S3 is precipitated in a sedimentation tank, the sludge in the sedimentation tank is backflowed to the primary full-mix denitrification tank, and the sludge concentration in the primary full-mix denitrification tank is controlled at 4 g / L; the effluent is discharged into a discharge tank; and the remaining sludge in the sedimentation tank is discharged to a sludge thickening tank.

[0060] Under the above treatment steps, first, a 2-month debugging is performed; during the debugging, the total salt concentration is gradually increased from about 800 mg / L to about 40,000 mg / L, the nitrate nitrogen concentration of the influent is gradually increased from 40 mg / L to about 300 mg / L, and the total nitrogen of the influent is gradually increased from 60 mg / L to 350 mg / L; after the debugging is completed and passed the acceptance, the average concentration of nitrate nitrogen of the effluent of the discharge tank is 5.6 mg / L, and the average concentration of total nitrogen is 11.4 mg / L, and the effluent reaches the first level A standard (TN≤15 mg / L) of the “Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant” GB 18918-2002.

[0061] The equipment list and operation cost accounting of the biological denitrification treatment in this embodiment and the traditional concentration and evaporation treatment are shown in Table 1 and Table 2.

[0062] Table 1 Equipment list

[0063]

[0064] Table 2 Operation cost accounting

[0065]

[0066] The biochemical treatment investment cost includes the purchase of a set of carbon source adding device, 4 sludge backflow pumps, 1 air blower, 1 batch of composite bacterial agent, and part of the biochemical tank body and pipeline reconstruction cost, which is much lower than the MVR evaporator required for evaporation and concentration.

[0067] The biochemical treatment operation cost includes the cost of reagents and electricity, which is much lower than the operation electricity cost of the MVR evaporator and the cost of outsourcing treatment of solid (hazardous) waste generated by using the evaporation and concentration technology.

[0068] Example 2

[0069] The denitrification method for treating high-salt and high-nitrate nitrogen wastewater in the system in Example 1 is used to treat the desorption liquid of the denitrification resin, the treatment water volume is 70 tons / day, the salt concentration in the wastewater is about 35000 mg / L, and the nitrate nitrogen concentration is 800 mg / L; the method comprises the following steps:

[0070] S1 adjusts the pH of the high-salt and high-nitrate nitrogen wastewater to 6-6.5, and denitrification is performed in a first full-mixing denitrification tank; the composite microbial inoculant is added to the first full-mixing denitrification tank at one time, the composition of the composite microbial inoculant is Marinobacter hydrocarbonoclasticus (item number B69399, preservation number ATCC: 49840), Azoarcus Indigens (item number bio-091253, preservation number ATCC: 51398), Paracoccus Denitrificans (item number bio-02824), Bacillus Azotoformans (item number bio-110716, preservation number ATCC 29788), and Pseudomonas Stutzeri (item number bio-83626, preservation number: ATCC: 14405), the mixing ratio is 30%:30%:10%:10%:20%, the mass of the composite microbial inoculant is 0.5‰ of the total volume of the reactor, and the mass of the composite microbial inoculant is the dry weight of the composite microbial inoculant; during the treatment, carbon sources, acetic acid and glucose, are added to the first full-mixing denitrification tank to maintain the C:N ratio in the first full-mixing denitrification tank at 2-4:1;

[0071] S2 denitrification is performed on the effluent of step S1 using a second full-mixing denitrification tank; during the operation of the second full-mixing denitrification tank, a mud-water mixture is backflowed to the first full-mixing denitrification tank, and the backflow ratio is 30%;

[0072] The total residence time of the first full-mixing denitrification tank and the second full-mixing denitrification tank in step S1 is 8h;

[0073] S3 the effluent of step S2 enters a degassing tank for degassing, and air is blown into the degassing tank for stirring;

[0074] S4 after the effluent of step S3 is precipitated in a sedimentation tank, the sludge in the sedimentation tank is backflowed to the first full-mixing denitrification tank in step S1, the sludge concentration in the first full-mixing denitrification tank is controlled at 5 g / L; the effluent is discharged into a discharge tank; and the remaining sludge in the sedimentation tank is discharged to a sludge thickening tank.

[0075] Under the above treatment steps, first, 2 months of debugging are carried out, during the debugging, the total salt concentration is gradually increased from about 300 mg / L to about 35000 mg / L, the nitrate nitrogen concentration of the influent is gradually increased from 90 mg / L to about 800 mg / L, and the total nitrogen of the influent is gradually increased from 110 mg / L to 820 mg / L; after the debugging is completed and is accepted, the average concentration of nitrate nitrogen of the effluent of the pool to be discharged for 3 months is 9.6 mg / L, the average concentration of total nitrogen is 15.8 mg / L, and the effluent reaches the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant

[0076] GB18918-2002 Level B standard (TN≤20 mg / L).

[0077] Example 3

[0078] The denitrification method for treating high-salt and high-nitrate wastewater by using the above system, treating high-salt and high-nitrate wastewater in the electroplating park, the treatment water volume is 50 tons / day, the salt concentration in the wastewater is about 30000 mg / L, and the nitrate nitrogen concentration is 1000 mg / L; the method comprises the following steps:

[0079] S1 adjusts the pH of the high-salt and high-nitrate wastewater to 6-6.5, and uses a primary full-mix denitrification tank for denitrification; the composite microbial agent is added into the primary full-mix denitrification tank at one time, and the composition of the composite microbial agent is: 2:1 mixed Marinobacterium Nitratireducens (Bio-03321) of Marinobacter hydrocarbonoclasticus (B69399), Azoarcus Indigens (Bio-091253, preservation number ATCC: 51398), Paracoccus Denitrificans (Bio-02824), Bacillus Azotoformans (Bio-110716, preservation number ATCC 29788), and Pseudomonas Stutzeri (Bio-83626, preservation number: ATCC: 14405), and the mixing ratio is 30%:30%:10%:10%:20%, and the composite microbial agent is added in an amount of 0.5‰ of the total volume of the reactor; during the treatment, carbon sources, acetic acid and glucose, are added into the primary full-mix denitrification tank, so that the C:N in the primary full-mix denitrification tank is kept between 2-4:1;

[0080] S2 uses a secondary full-mix denitrification tank for denitrification for the effluent of step S1; during the operation of the secondary full-mix denitrification tank, the mud-water mixture is backflowed into the primary full-mix denitrification tank, and the backflow ratio is 50%;

[0081] The total residence time of the primary and secondary full-mix denitrification tanks is 10 h;

[0082] In step S3, the effluent from step S2 is subjected to degassing in a degassing tank, and air is blown into the degassing tank for agitation;

[0083] In step S4, the effluent from step S3 is subjected to sedimentation in a sedimentation tank, and the sludge in the sedimentation tank is returned to the primary full-mix denitrification tank to control the sludge concentration in the primary full-mix denitrification tank at 5 g / L; the effluent is discharged into a discharge tank; and the remaining sludge in the sedimentation tank is discharged into a sludge thickening tank.

[0084] Under the above treatment steps, first, a 2-month commissioning is performed, during which the total salt concentration is gradually increased from about 2000 mg / L to about 30000 mg / L, the nitrate nitrogen concentration in the influent is gradually increased from 50 mg / L to about 1000 mg / L, and the total nitrogen in the influent is gradually increased from 55 mg / L to 1030 mg / L; after the commissioning is completed and acceptance is passed, the average concentration of nitrate nitrogen in the effluent of the discharge tank is 10.6 mg / L, and the average concentration of total nitrogen is 15.4 mg / L, and the effluent meets the first B standard (TN≤20 mg / L) of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002).

[0085] Example 4

[0086] This example is directed to high-salt and high-nitrate wastewater, and the system and treatment steps used are basically the same as those in Example 1, except that:

[0087] The desorption liquid of the denitrification resin pilot plant is treated, the water quantity is 10 tons / day, the salt concentration in the wastewater is about 23000 mg / L, and the nitrate nitrogen concentration is 600 mg / L;

[0088] In step S1, the complex microbial inoculant contains 40% Marinobacter hydrocarbonoclasticus (item number B69399, accession number ATCC: 49840), 20% Azoarcus Indigens (item number bio-091253, accession number ATCC: 51398), 20% Paracoccus Denitrificans (item number bio-02824), 10% Bacillus Azotoformans (item number bio-110716, accession number ATCC 29788), and 10% Pseudomonas Stutzeri (item number bio-83626, accession number ATCC: 14405), and the dosage is 0.2 ‰;

[0089] The sludge-water mixture is returned to the first full-mix denitrification tank in step S2, and the return ratio is 25%;

[0090] The sludge in the sedimentation tank is returned to the first full-mix denitrification tank in step S4, and the sludge concentration in the first full-mix denitrification tank is controlled at 4 g / L;

[0091] Under the above treatment steps, first, a debugging is performed for 1 month. During the debugging, the total salt concentration is gradually increased from about 400 mg / L to about 23,000 mg / L, the nitrate nitrogen concentration in the influent is gradually increased from 50 mg / L to about 600 mg / L, and the total nitrogen in the influent is gradually increased from 60 mg / L to 630 mg / L. After the debugging is completed and passed, the average concentration of nitrate nitrogen in the effluent of the discharge tank is 4.5 mg / L, and the average concentration of total nitrogen is 10.6 mg / L. The effluent meets the first A standard (TN≤15 mg / L) of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002).

[0092] Example 5

[0093] This example is directed to high-salt and high-nitrate wastewater. The system and treatment steps used are basically the same as those in Example 1, except that:

[0094] The desorption liquid of the denitrification resin device is treated on site for pilot treatment of tail water. The water treatment capacity is 1 ton / day. The salt concentration in the wastewater is about 40,000 mg / L, and the nitrate nitrogen concentration is 300 mg / L.

[0095] In step S1, the composite microbial inoculant contains 40% Marinobacter hydrocarbonoclasticus (item number B69399, preservation number ATCC: 49840), 20% Azoarcus Indigens (item number bio-091253, preservation number ATCC: 51398), 20% Paracoccus Denitrificans (item number bio-02824), 10% Bacillus Azotoformans (item number bio-110716, preservation number ATCC 29788), and 10% Pseudomonas Stutzeri (item number bio-83626, preservation number: ATCC: 14405). The dosage is 0.2 ‰.

[0096] The sludge-water mixture is returned to the first full-mix denitrification tank in step S2, and the return ratio is 25%;

[0097] The sludge in the sedimentation tank is returned to the first full-mix denitrification tank in step S4, and the sludge concentration in the first full-mix denitrification tank is controlled at 4 g / L;

[0098] First, as Figure 2 (nitrate nitrogen) and Figure 3 (total nitrogen), during commissioning, within 14 days, the total salt concentration gradually increased from 3000 mg / L to about 42000 mg / L, the influent nitrate nitrogen concentration gradually increased from 80 mg / L to about 340 mg / L, and the influent total nitrogen gradually increased from 110 mg / L to 430 mg / L. Through 18 days of commissioning, after passing the acceptance, the average concentration of effluent nitrate nitrogen was 2.1 mg / L, and the average concentration of total nitrogen was 12.3 mg / L. The effluent reached the first level A standard (TN≤15 mg / L) of "Urban Sewage Treatment Plant Pollutant Discharge Standard" GB18918-2002.

[0099] Comparative Example 1

[0100] This comparative example is aimed at high-salt and high-nitrate wastewater. The system and treatment steps used are basically the same as in Example 1, except that:

[0101] The laboratory pilot test treated the desorption liquid of the tail water denitrification resin device. The water treatment capacity was 30 L / d, the salt concentration in the wastewater was about 40000 mg / L, and the nitrate nitrogen concentration was 300 mg / L.

[0102] The step S1 composite microbial inoculant was single Marinobacter hydrocarbonoclasticus (Marinobacter hydrocarbonoclasticus, item number B69399, accession number ATCC: 49840) 100%, and the dosage was 0.2 ‰.

[0103] After the above treatment, the average concentration of effluent nitrate nitrogen was 19.6 mg / L, the average concentration of effluent nitrite nitrogen was 48.3 mg / L, and the average concentration of effluent total nitrogen was 87.3 mg / L. The experiment found that there was a problem of nitrite accumulation in the system, which caused the total nitrogen in the effluent to exceed the standard. This is because nitrate reductase is widely distributed in Marinobacter, and nitrite reductase and nitrous oxide reductase are narrowly distributed, so the ability to reduce nitrite is weak, causing accumulation.

[0104] Comparative Example 2

[0105] This comparative example is aimed at high-salt and high-nitrate wastewater. The system and treatment steps used are basically the same as in Example 1, except that:

[0106] The laboratory pilot test treated the desorption liquid of the tail water denitrification resin device. The water treatment capacity was 30 L / d, the salt concentration in the wastewater was about 40000 mg / L, and the nitrate nitrogen concentration was 300 mg / L.

[0107] Step S1 Marinobacter hydrocarbonoclasticus (B69399, ATCC: 49840) 55%, Azoarcus Indigens (bio-091253, ATCC: 51398) 15%, Paracoccus Denitrificans (bio-02824) 10%, Bacillus Azotoformans (bio-110716, ATCC 29788) 10%, Pseudomonas Stutzeri (bio-83626, ATCC: 14405) 10% in the composite microbial inoculant, and the dosage is 0.2 ‰.

[0108] After the above treatment, the average concentration of nitrate nitrogen in the effluent is 8.1 mg / L, the average concentration of nitrite nitrogen is 28.6 mg / L, and the average concentration of total nitrogen is 38.3 mg / L.

[0109] The results and experiments of Comparative Example 1 and Comparative Example 2 show that Marinobacter hydrocarbonoclasticus and Azoarcus Indigens, Paracoccus Denitrificans can remove nitrate nitrogen, but when all are Marinobacter hydrocarbonoclasticus or the proportion of Marinobacter hydrocarbonoclasticus is significantly higher than that of Azoarcus Indigens and Paracoccus Denitrificans, the problem of nitrite nitrogen accumulation may occur in the system, causing the total nitrogen in the effluent to exceed the standard. This is because nitrate reductase is widely distributed in Marinobacter hydrocarbonoclasticus, and nitrite reductase and nitrous oxide reductase are less distributed, so the ability to reduce nitrite is weak, causing nitrite accumulation and difficulty in reducing the total nitrogen concentration to the required concentration.

[0110] The above content is a schematic description of the present application and its embodiments, which is not restrictive. The embodiments shown in the examples are only one of the embodiments of the present application, and the actual embodiments are not limited thereto. Therefore, if a person skilled in the art is inspired by it, without departing from the spirit of the present application, similar embodiments and examples can be designed without creative design, which should belong to the protection scope of the present application.

Claims

1. A method for denitrifying high-salt, high-nitrate nitrogen wastewater, characterized in that, The high-salt, high-nitrate-nitrogen wastewater has a salt concentration between 6000 and 40000 mg / L and a nitrate-nitrogen concentration between 300 and 1000 mg / L; the method includes the following steps: S1 adjusts the pH of the high-salt, high-nitrate nitrogen wastewater to the range of 5.5-7.5, and then performs denitrification using a primary mixed-state denitrification tank. A compound microbial agent containing *Gynostemma pentaphyllum* is added to the primary mixed-state denitrification tank in a single step. Marinobacter genus *Vibrio zonesia* Azoarcus Paracoccus Paracoccus Bacillus Bacillus Pseudomonas spp. Pseudomonas The compound microbial agent contains 30%–40% *Leptobacter*, 20%–30% *Vibrio azotobacter*, 20%–30% *Paracococcus*, 5%–10% *Bacillus*, and 10%–20% *Pseudomonas*, wherein the *Leptobacter* genus includes *Leptobacter* excluding *Hydrocotyle*. Marinobacter hydrocarbonoclasticus or nitrate-reduced sea bacteria Marinobacterium Nitratireducens One or two of the species, wherein the *Leptobacter* genus excluding *Leptobacter cyclohexane*. Marinobacter hydrocarbonoclasticus The accession number is ATCC:49840, and the nitrate-reducing marine bacillus is described. Marinobacterium Nitratireducens The accession number is JCM:15523; S2 Denitrification is performed on the effluent from step S1 using a two-stage fully mixed state denitrification tank; during the operation of the two-stage fully mixed state denitrification tank, the sludge-water mixture is returned to the first-stage fully mixed state denitrification tank; S3 The effluent from S2 enters the degassing tank for degassing; S4 The effluent from step S3 is discharged after sedimentation in the sedimentation tank.

2. The method for denitrifying high-salt, high-nitrate nitrogen wastewater according to claim 1, characterized in that, In step S1, the genus *Vibrio zones* includes *Vibrio zones*. Azoarcus Indigens ; In step S1, *Paracococcus denitrificans* includes *Paracococcus denitrificans*. Paracoccus denitrificans ; In step S1, the genus Bacillus includes Bacillus. Bacillus Azotoformans ; In step S1, the genus *Pseudomonas* includes *Pseudomonas stearothermiae*. Pseudomonas Stutzeri .

3. The method for denitrifying high-salt, high-nitrate nitrogen wastewater according to claim 1, characterized in that, In step S1, the mass ratio of the compound microbial agent to the total volume of the reactor is 0.1‰-0.5‰, and the mass of the compound microbial agent is the dry weight of the compound microbial agent.

4. The method for denitrifying high-salt, high-nitrate nitrogen wastewater according to claim 1, characterized in that, In step S1, the pH of the high-salt, high-nitrate nitrogen wastewater is adjusted to the range of 6.0 to 7.

0.

5. The method for denitrifying high-salt, high-nitrate nitrogen wastewater according to claim 1, characterized in that, In step S2, the recirculation ratio of the mud-water mixture from the secondary fully mixed state denitrification tank to the primary fully mixed state denitrification tank is 25%~50%.

6. The method for denitrifying high-salt, high-nitrate nitrogen wastewater according to claim 1, characterized in that, In step S4, the sludge from the sedimentation tank is returned to the primary mixed-state denitrification tank, and the sludge concentration in the primary mixed-state denitrification tank is controlled at 4~6 g / L.

7. The method for denitrifying high-salinity, high-nitrate nitrogen wastewater according to any one of claims 1 to 6, characterized in that, The retention time of high-salt, high-nitrate nitrogen wastewater in the primary and secondary mixed-state denitrification tanks is greater than 6 hours.

8. The method for denitrifying high-salt, high-nitrate nitrogen wastewater according to claim 7, characterized in that, In step S4, the effluent after sedimentation is then treated by nanofiltration membrane.

Images