Denitrification treatment device and method for high-ammonia-nitrogen low-COD (Chemical Oxygen Demand) wastewater

Abstract

The invention discloses a high-ammonia-nitrogen low-COD (Chemical Oxygen Demand) wastewater denitrification treatment device and method. The wastewater denitrification treatment device comprises a water inlet system, a biological denitrification system, an aeration system, a dosing system, a mixed liquid solid-liquid separation system, a precipitation concentration and reflux system and a control system, the water inlet system is connected with the biological denitrification system; the mixed liquid solid-liquid separation system is arranged in the biological denitrification system; the aeration system is connected with the biological denitrification system; the dosing system is connected with the biological denitrification system; the water inlet end of the precipitation concentration and reflux system is connected with the water outlet end of the biological denitrification system; the control system is respectively connected with the precipitation concentration and reflux system, the water inlet system, the biological denitrification system, the aeration system and the dosing system. The method keeps the advantage that nitration reaction and anaerobic ammonia oxidation reaction can be carried out at the same time, is flexible to control and easy to adjust, and is suitable for removing ammonia nitrogen and total nitrogen in high-ammonia-nitrogen low-COD wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of biological denitrification of wastewater, and in particular relates to a denitrification treatment device and method for wastewater with high ammonia nitrogen and low COD. Background Art

[0002] In recent years, with the advancement of technology and in-depth research, new biological denitrification technology has made breakthrough progress, among which anaerobic ammonium oxidation (Anammox) new denitrification technology has entered the stage of industrial promotion and application. Compared with traditional nitrification and denitrification, anaerobic ammonium oxidation denitrification technology has the characteristics of low energy consumption, low cost, low pollution and high efficiency. The common process forms based on the principle of anaerobic ammonium oxidation denitrification are one-stage (such as complete autotrophic denitrification process (CANON)) and two-stage (such as short-term nitrification and denitrification-anaerobic ammonium oxidation process (sharon-anammox)). The difference between the two is whether the short-term nitrification and anaerobic ammonium oxidation reactions occur in the same reactor. The CANON process achieves partial nitrification and anaerobic ammonium oxidation reactions in the same reactor under the conditions of limiting dissolved oxygen DO and adjusting pH, but due to the low DO level, the ammonia nitrogen conversion rate is low, resulting in low efficiency of anaerobic ammonium oxidation reaction. Although partial nitrification and anaerobic ammonium oxidation reactions are carried out efficiently in their respective reactors in the SHARON process, the nitrification stage is prone to large-scale reproduction of nitrate bacteria (NOB), resulting in partial nitrification turning into complete nitrification, thus failing to meet the Anammox process's requirements for the influent substrate. Summary of the invention

[0003] In view of the above problems, the present invention discloses a high-ammonia-nitrogen and low-COD wastewater denitrification treatment device, comprising: a water inlet system, a biological denitrification system, an aeration system, a dosing system, a mixed liquid solid-liquid separation system, a precipitation concentration and reflux system and a control system;

[0004] The water inlet system is connected to the biological denitrification system;

[0005] The mixed liquid solid-liquid separation system is arranged in the biological denitrification system;

[0006] The aeration system is connected to the biological denitrification system;

[0007] The dosing system is connected to the biological denitrification system;

[0008] The water inlet of the precipitation concentration and reflux system is connected to the water outlet of the biological denitrification system;

[0009] The control system is respectively connected with the sedimentation concentration and reflux system, the water inlet system, the biological denitrification system, the aeration system and the dosing system.

[0010] Furthermore, the water inlet system comprises: a water tank, a water inlet pump and a first liquid level meter;

[0011] A first liquid level gauge is arranged in the water tank;

[0012] The water inlet end of the water inlet pump is connected to the water tank, and the water outlet end is connected to the biological denitrification system;

[0013] The water inlet pump and the first liquid level meter are respectively connected to the control system.

[0014] Furthermore, the biological denitrification system includes an anaerobic ammonium oxidation reaction zone, a nitrification reaction zone and a terminal anaerobic ammonium oxidation reaction zone;

[0015] The anaerobic ammonium oxidation reaction zone is arranged on both sides of the nitrification reaction zone, and the two are connected;

[0016] The anaerobic ammonium oxidation reaction zone is divided into a plurality of independent anaerobic ammonium oxidation reaction sections connected in parallel by a partition, and the anaerobic ammonium oxidation reaction sections are all connected to the nitrification reaction zone;

[0017] The water outlet of the nitrification reaction zone is connected to the terminal anaerobic ammonia oxidation reaction zone, and the water inlet is connected to the water outlet of the water inlet pump;

[0018] A third liquid level gauge is provided in the terminal anaerobic ammonium oxidation reaction zone;

[0019] The third liquid level meter is connected to the control system.

[0020] Furthermore, it also includes: a submerged plug flow pump;

[0021] A bottom communicating orifice is provided between each of the anaerobic ammonium oxidation reaction sections and the nitrification reaction zone;

[0022] A submersible plug flow pump is provided in the bottom communicating hole;

[0023] The water flow angle θ between the outlet direction of the submerged plug flow pump and the flow direction of the nitrification mixed liquid in the nitrification reaction zone is between 0° and 180°;

[0024] The submerged plug flow pump is connected to a control system.

[0025] Furthermore, the mixed liquid solid-liquid separation system includes a diversion area, a mud bucket, a sedimentation area and a clear water area;

[0026] A plurality of the mixed liquid solid-liquid separation systems are arranged in the nitrification reaction zone of the biological denitrification system, and each of the mixed liquid solid-liquid separation systems corresponds to an anaerobic ammonium oxidation reaction section;

[0027] The upper end of the diversion zone is the water inlet end, connected to the nitrification reaction zone, and the lower end is connected to the precipitation zone;

[0028] The sedimentation area is located above the mud bucket and below the clean water area;

[0029] The upper end of the clean water zone is the water outlet, which is connected to the anaerobic ammonium oxidation reaction section;

[0030] The mud outlet at the bottom of the mud hopper is connected to the nitrification reaction zone.

[0031] Furthermore, the aeration system includes a fan, a solenoid valve and an aeration device;

[0032] The fan and the solenoid valve are respectively connected to the control system;

[0033] The fans are respectively connected to a plurality of solenoid valves;

[0034] The solenoid valve is connected to the aeration equipment;

[0035] The plurality of aeration devices are arranged at intervals in the nitrification reaction zone.

[0036] Furthermore, the dosing system includes a drug liquid tank, a dosing pump, a second liquid level meter and a stirrer;

[0037] A second liquid level gauge and a stirrer are provided in the liquid medicine tank;

[0038] One end of the dosing pump is connected to the drug liquid tank, and the other end is connected to the biological denitrification system;

[0039] The dosing pump and the second liquid level meter are respectively connected to the control system.

[0040] Furthermore, the sedimentation concentration and reflux system comprises a sedimentation concentration tank, a sludge reflux pump, a water outlet and a sludge discharge pipe;

[0041] The water inlet of the sedimentation and concentration tank is connected to the water outlet of the terminal anaerobic ammonia oxidation reaction zone;

[0042] The sedimentation and concentration tank is provided with a water outlet and a sludge outlet;

[0043] The sludge outlet is connected to the feed end of the sludge reflux pump and the sludge discharge pipe respectively;

[0044] The discharge end of the sludge reflux pump is connected to the nitrification reaction zone;

[0045] The sludge return pump is connected to a control system.

[0046] Furthermore, the control system includes online monitoring instruments and a PLC control cabinet;

[0047] The online monitoring instrumentation includes a plurality of online multi-parameter monitoring probes;

[0048] The plurality of online multi-parameter monitoring probes are respectively arranged in the plurality of anaerobic ammonium oxidation reaction sections and nitrification reaction zones, and are respectively connected to online monitoring instruments;

[0049] The online monitoring instrument is connected to the PLC control cabinet.

[0050] The present invention also discloses a wastewater denitrification treatment method based on the above-mentioned high-ammonia-nitrogen and low-COD wastewater denitrification treatment device, comprising the following steps:

[0051] The high-ammonia-nitrogen and low-COD wastewater first enters the nitrification reaction zone for partial nitrification reaction, oxidizing part of the ammonia nitrogen in the high-ammonia-nitrogen and low-COD wastewater into nitrite nitrogen, and forming a nitrification mixed liquid containing residual ammonia nitrogen and newly generated nitrite nitrogen;

[0052] The nitrification mixed liquid simultaneously / separately enters the mixed liquid solid-liquid separation system for solid-liquid separation, and the nitrification mixed liquid is separated into supernatant and nitrification sludge;

[0053] The nitrified sludge settles freely and falls back to the nitrification reaction zone. The supernatant enters the anaerobic ammonium oxidation reaction section for anaerobic ammonium oxidation denitrification reaction, removing all nitrite nitrogen and part of ammonia nitrogen in the supernatant. The denitrified supernatant is returned to the nitrification reaction zone through a submerged plug flow pump, and the remaining ammonia nitrogen continues to undergo nitrification reaction.

[0054] The nitrification mixed liquid undergoes multiple anaerobic ammonium oxidation denitrification reactions in multiple parallel anaerobic ammonium oxidation reaction sections;

[0055] When the high-ammonia-nitrogen and low-COD wastewater reaches the end of the nitrification reaction zone after multiple denitrification treatments, the ammonia-nitrogen concentration of the nitrification mixed liquid is ≤20mg / L. The nitrification mixed liquid enters the terminal anaerobic ammonia oxidation reaction zone for anaerobic ammonia oxidation denitrification treatment to complete further deep denitrification.

[0056] The nitrification mixed liquor after deep denitrification treatment enters the sedimentation, concentration and reflux system. The sludge separated by sedimentation is returned to the nitrification reaction zone by the sludge reflux pump or discharged from the sludge discharge pipe, and the separated clean water is discharged from the outlet. The terminal control parameters of the nitrification reaction zone are: DO = 0 ~ 0.5 mg / L, pH = 7.5 ~ 8.2.

[0057] Furthermore, the control system of the nitrification reaction zone adjusts the oxygen supply and dosage of the aeration system according to the monitoring data of the dissolved oxygen DO and pH value in the nitrification reaction zone;

[0058] Control parameters: DO = 0 ~ 3.5 mg / L, pH = 7.2 ~ 9.5, mixed liquor suspended solids concentration MLSS = 2000 ~ 6000 mg / L, hydraulic retention time HRT = 4 ~ 8h.

[0059] Furthermore, the reflux ratio R of the nitration mixture is 0-300%.

[0060] Furthermore, the control parameters of each anaerobic ammonium oxidation reaction section are: DO≤0.5mg / L, pH=7.0-8.5, HRT=1.0-3.0h.

[0061] Furthermore, the flow state of the nitration mixed liquid in the nitration reaction zone is a plug flow mode or a circulation mode.

[0062] Compared with the prior art, the embodiments of the present invention have at least the following advantages:

[0063] 1. The present invention not only maintains the advantage that the nitrification reaction and the anaerobic ammonium oxidation reaction can be carried out almost simultaneously in the one-stage partial nitrification-anaerobic ammonium oxidation device, but also solves the mutual influence between the aerobic partial nitrification reaction and the anaerobic anaerobic ammonium oxidation reaction in the one-stage device, and at the same time avoids the problems of difficult control of the nitrification reaction process and strict requirements on the ratio of ammonia nitrogen to nitrite nitrogen in the two-stage device. The device is flexible in control and easy to adjust, and is suitable for the removal of ammonia nitrogen and total nitrogen in high-ammonia nitrogen and low-COD wastewater;

[0064] 2. First, the nitrification reaction zone is used to complete a partial nitrification reaction to form a wastewater nitrification mixed solution containing ammonia nitrogen and nitrite nitrogen, and the wastewater nitrification mixed solution is simultaneously subjected to multiple cycles of sequential denitrification treatment in the anaerobic ammonium oxidation reaction section connected in parallel to the anaerobic ammonium oxidation reaction zone;

[0065] 3. During the denitrification treatment process, under low dissolved oxygen conditions, a small amount of ammonia nitrogen is converted into nitrite nitrogen through nitrification reaction to continuously form a wastewater nitrification mixed solution containing nitrite nitrogen and ammonia nitrogen. At the same time, the anaerobic ammonia oxidation reaction zone is used to remove nitrite nitrogen and part of ammonia nitrogen in the wastewater nitrification mixed solution. The remaining ammonia nitrogen is returned to the nitrification reaction zone with the wastewater nitrification mixed solution to continue the nitrification reaction. The alkali generated during the anaerobic ammonia oxidation reaction is returned to the nitrification reaction zone with the wastewater nitrification mixed solution, which means that the amount of alkali added in the nitrification reaction section is correspondingly reduced; at the same time, the inhibitory effect of free ammonia (FA) at the head end of the nitrification reaction zone and free nitrite (FNA) in the circulating mixed solution on nitrate bacteria (NOB) is fully utilized, which is conducive to the device to stably maintain the nitrification reaction zone in the nitrification stage.

[0066] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, taking the three-stage anaerobic ammonia oxidation reaction partition as an example, the following is a brief introduction to the drawings required for use in the embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0068] Figure 1 It shows a schematic diagram of the plan layout and control of a high-ammonia-nitrogen and low-COD wastewater denitrification treatment device according to an embodiment of the present invention;

[0069] Figure 2 A cross-sectional view of a mixed liquid solid-liquid separation system according to an embodiment of the present invention is shown.

[0070] Reference numerals: 1. water inlet pump;

[0071] 2-1, first liquid level gauge; 2-2, second liquid level gauge; 2-3, third liquid level gauge;

[0072] 3. Anaerobic ammonium oxidation reaction zone; 3-1. First anaerobic ammonium oxidation reaction section; 3-2. Second anaerobic ammonium oxidation reaction section; 3-3. Third anaerobic ammonium oxidation reaction section; 3-4. Fourth anaerobic ammonium oxidation reaction section; 3-5. Fifth anaerobic ammonium oxidation reaction section; 3-6. Sixth anaerobic ammonium oxidation reaction section;

[0073] 4. Nitrification reaction zone;

[0074] 5. Mixed liquid solid-liquid separation system; 5-1. First mixed liquid solid-liquid separation system; 5-2. Second mixed liquid solid-liquid separation system; 5-3. Third mixed liquid solid-liquid separation system; 5-4. Fourth mixed liquid solid-liquid separation system; 5-5. Fifth mixed liquid solid-liquid separation system; 5-6. Sixth mixed liquid solid-liquid separation system; 5-7. Diversion area; 5-8. Mud bucket; 5-9. Sedimentation area; 5-10. Clean water area;

[0075] 6. Submerged plug flow pump; 6-1. First submerged plug flow pump; 6-2. Second submerged plug flow pump; 6-3. Third submerged plug flow pump; 6-4. Fourth submerged plug flow pump; 6-5. Fifth submerged plug flow pump; 6-6. Sixth submerged plug flow pump;

[0076] 7. Terminal anaerobic ammonium oxidation reaction zone;

[0077] 8. Fan;

[0078] 9-1, first solenoid valve; 9-2, second solenoid valve; 9-3, third solenoid valve;

[0079] 10-1, first aeration equipment; 10-2, second aeration equipment; 10-3, third aeration equipment;

[0080] 11. Dosing pump;

[0081] 12. Online monitoring instruments; 12-1. First online multi-parameter monitoring probe; 12-2. Second online multi-parameter monitoring probe; 12-3. Third online multi-parameter monitoring probe; 12-4. Fourth online multi-parameter monitoring probe; 12-5. Fifth online multi-parameter monitoring probe; 12-6. Sixth online multi-parameter monitoring probe; 12-7. Seventh online multi-parameter monitoring probe; 12-8. Eighth online multi-parameter monitoring probe; 12-9. Ninth online multi-parameter monitoring probe;

[0082] 13. PLC control cabinet;

[0083] 14. Sludge return pump;

[0084] 15. Water outlet;

[0085] 16. Mud discharge pipe;

[0086] 17. Water tank;

[0087] 18. Liquid medicine tank;

[0088] 19. Sedimentation and concentration tank. DETAILED DESCRIPTION

[0089] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0090] like Figure 1 As shown, a high-ammonia-nitrogen and low-COD wastewater denitrification treatment device proposed by the present invention includes: a water inlet system, a biological denitrification system, an aeration system, a dosing system, a mixed liquid solid-liquid separation system 5, a precipitation concentration and reflux system and a control system;

[0091] The water inlet system is connected to the biological denitrification system;

[0092] The mixed liquid solid-liquid separation system 5 is arranged in the biological denitrification system;

[0093] The aeration system is connected to the biological denitrification system;

[0094] The dosing system is connected to the biological denitrification system;

[0095] The water inlet of the precipitation concentration and reflux system is connected to the water outlet of the biological denitrification system;

[0096] The control system is respectively connected with the sedimentation concentration and reflux system, the water inlet system, the biological denitrification system, the aeration system and the dosing system.

[0097] The present invention not only maintains the advantage that the nitrification reaction and the anaerobic ammonium oxidation reaction in the one-stage partial nitrification-anaerobic ammonium oxidation device can be carried out almost simultaneously, but also solves the mutual influence between the aerobic nitrification reaction and the anaerobic anaerobic ammonium oxidation reaction in the one-stage device, and at the same time avoids the problems of difficult control of the nitrification reaction process and strict requirements on the ratio of ammonia nitrogen to nitrite nitrogen in the two-stage device. The device is flexible in control and easy to adjust, and is suitable for the removal of ammonia nitrogen and total nitrogen in wastewater with high ammonia nitrogen and low COD (chemical oxygen demand).

[0098] In some embodiments, the water inlet system includes: a water tank 17, a water inlet pump 1 and a first liquid level meter 2-1;

[0099] A first liquid level gauge 2-1 is provided in the water tank 17;

[0100] The water inlet end of the water inlet pump 1 is connected to the water tank 17, and the water outlet end is connected to the nitrification reaction zone 4 of the biological denitrification system;

[0101] The water inlet pump 1 and the first liquid level meter 2-1 are respectively connected to the control system.

[0102] The water tank 17 stores high-ammonia-nitrogen and low-COD wastewater, and supplies the high-ammonia-nitrogen and low-COD wastewater to the biological denitrification system through the water inlet pump 1.

[0103] In some embodiments, the biological denitrification system includes a nitrification reaction zone 4, an anaerobic ammonium oxidation reaction zone 3, and a terminal anaerobic ammonium oxidation reaction zone 7;

[0104] The anaerobic ammonium oxidation reaction zone 3 is arranged on both sides of the nitrification reaction zone 4, and the two are connected;

[0105] In the embodiments of the present invention, three-stage anaerobic ammonium oxidation reaction zones are taken as an example, that is, the anaerobic ammonium oxidation reaction zone 3 is divided into a first-stage anaerobic ammonium oxidation reaction zone, a second-stage anaerobic ammonium oxidation reaction zone, and a third-stage anaerobic ammonium oxidation reaction zone;

[0106] The anaerobic ammonium oxidation reaction zone 3 arranged on both sides of the nitrification reaction zone 4 is divided into parallel independent anaerobic ammonium oxidation reaction sections by partitions according to the classification, and the first-stage anaerobic ammonium oxidation reaction zone includes: a first anaerobic ammonium oxidation reaction section 3-1 and a second anaerobic ammonium oxidation reaction section 3-2; the second-stage anaerobic ammonium oxidation reaction section includes: a third anaerobic ammonium oxidation reaction section 3-3 and a fourth anaerobic ammonium oxidation reaction section 3-4; the third-stage anaerobic ammonium oxidation reaction section includes: a fifth anaerobic ammonium oxidation reaction section 3-5 and a sixth anaerobic ammonium oxidation reaction section 3-6, and the anaerobic ammonium oxidation reaction sections are connected to the nitrification reaction zone 4 through the mixed liquid solid-liquid separation system 5 and the submerged plug flow pump 6; wherein the first anaerobic ammonium oxidation reaction section 3-1, the third anaerobic ammonium oxidation reaction section 3-3 and the fifth anaerobic ammonium oxidation reaction section 3-5 are arranged on one side of the nitrification reaction zone 4 in sequence; the second anaerobic ammonium oxidation reaction section 3-2, the fourth anaerobic ammonium oxidation reaction section 3-4, and the sixth anaerobic ammonium oxidation reaction section 3-6 are arranged on the other side of the nitrification reaction zone 4.

[0107] The water outlet of the nitrification reaction zone 4 is connected to the terminal anaerobic ammonia oxidation reaction zone 7, and the water inlet is connected to the water outlet of the water inlet pump 1;

[0108] A third liquid level gauge 2-3 is provided in the terminal anaerobic ammonium oxidation reaction zone 7;

[0109] The third liquid level meter 2-3 is connected to the control system.

[0110] In some embodiments, the water outlet of the water inlet pump 1 is connected to the water inlet at the head end of the nitrification reaction zone 4 and / or multiple water inlets arranged along the way.

[0111] The nitrification reaction zone 4 is used for partial nitrification reaction. It is not necessary to strictly control the progress of the nitrification reaction. It is only necessary to maintain the necessary nitrification reaction conditions to convert a small amount of ammonia nitrogen into nitrite nitrogen, and provide a mixed solution containing nitrite nitrogen and ammonia nitrogen for the anaerobic ammonia oxidation reaction zone 3. The control system of the nitrification reaction zone 4 adjusts the oxygen supply of the aeration system and the dosage of the dosing system according to the monitoring data such as the dissolved oxygen DO and pH value of the nitrification reaction zone 4. Control parameters: DO = 0 ~ 3.5 mg / L, pH = 7.2 ~ 9.5, mixed solution suspended solids concentration MLSS = 2000 ~ 6000 mg / L, hydraulic retention time HRT = 4 ~ 8h.

[0112] Partial nitrification reaction is carried out in the nitrification reaction zone 4, and the ammonia nitrogen (smaller part) in the high ammonia nitrogen and low COD wastewater is gradually converted into nitrite nitrogen, thereby forming a nitrification mixed liquid containing residual ammonia nitrogen and newly generated nitrite nitrogen, and ammonia nitrogen is always kept relatively in excess in the nitrification reaction zone 4. The nitrification mixed liquid enters the solid-liquid separation zone along the water flow direction for mud and water separation, and the nitrified sludge freely settles back to the nitrification reaction zone 4, and the supernatant enters the anaerobic ammonia oxidation reaction zone 3 for anaerobic ammonia oxidation denitrification reaction. The remaining part of the nitrification mixed liquid continues to undergo nitrification reaction in the nitrification reaction zone 4.

[0113] The anaerobic ammonium oxidation reaction zone 3 is equipped with hanging or / and suspended biological fillers and an inlet weir plate. The supernatant of the mixed liquid solid-liquid separation system 5 is uniformly introduced into the anaerobic ammonium oxidation reaction zone 3 through the inlet weir plate, and a submerged plug flow pump 6 is arranged in the bottom communicating hole. The anaerobic ammonium oxidizing bacteria in the biological fillers of the anaerobic ammonium oxidation reaction zone 3 perform anaerobic ammonium oxidation denitrification reaction, remove nitrite nitrogen and part of ammonia nitrogen in the supernatant, and form a denitrified supernatant. The remaining ammonia nitrogen is refluxed to the nitrification reaction zone 4 by the submerged plug flow pump 6 with the denitrified supernatant to continue the nitrification reaction. The submerged plug flow pump 6 can not only adjust the treated water volume of the anaerobic ammonium oxidation reaction zone 3, but also provide power for the mixing and flow of the mixed liquid in the nitrification reaction zone 4. The submerged plug flow pump 6 is respectively arranged at the upstream position of the anaerobic ammonium oxidation reaction section. The control parameters of the anaerobic ammonium oxidation reaction section are: DO≤0.5mg / L, pH=7.0~8.5, HRT=1.0~3.0h.

[0114] The terminal anaerobic ammonium oxidation reaction zone 7 mainly carries out anaerobic ammonium oxidation denitrification reaction and short-range denitrification reaction to remove the remaining nitrite nitrogen, ammonia nitrogen and nitrate nitrogen in the nitrification mixed solution, complete the deep denitrification treatment, and ensure that the effluent of the device meets the standards.

[0115] The terminal anaerobic ammonium oxidation reaction zone 7 is provided with a hanging or suspended filler that simultaneously embeds anaerobic ammonium oxidizing bacteria and denitrifying bacteria. The nitrified mixed liquor entering the terminal anaerobic ammonium oxidation reaction zone 7 is further deeply denitrified by the anaerobic ammonium oxidizing bacteria and denitrifying bacteria in the hanging filler, and the remaining nitrite nitrogen, ammonia nitrogen and nitrate nitrogen in the mixed liquor are removed to ensure that the effluent of the device meets the standards. The nitrified mixed liquor after denitrification treatment finally enters the precipitation concentration and reflux system to complete solid-liquid separation, and discharges the wastewater, reflux or external sludge that has completed the denitrification treatment. The control parameters of the terminal anaerobic ammonium oxidation reaction zone 7 are: DO≤0.5mg / L, pH=7.0~8.5, hydraulic retention time HRT=1.0~2.0h.

[0116] The device of the present invention performs a nitrification reaction under aerobic conditions in the nitrification reaction zone 4 and performs an anaerobic ammonium oxidation reaction under anoxic / anaerobic conditions in the anaerobic ammonium oxidation reaction zone 3 to complete the denitrification function.

[0117] During the denitrification treatment process, under relatively low dissolved oxygen conditions, a small amount of ammonia nitrogen is converted into nitrite nitrogen through nitrification reaction to continuously form a wastewater nitrification mixed solution containing nitrite nitrogen and ammonia nitrogen. At the same time, the anaerobic ammonia oxidation reaction zone 3 is used to remove the nitrite nitrogen and part of the ammonia nitrogen in the wastewater nitrification mixed solution, and the remaining ammonia nitrogen is returned to the nitrification reaction zone 4 with the wastewater nitrification mixed solution to continue the nitrification reaction. The alkali generated during the anaerobic ammonia oxidation reaction is returned to the nitrification reaction zone 4 with the wastewater nitrification mixed solution, that is, the amount of alkali added in the nitrification reaction section is correspondingly reduced; at the same time, the inhibitory effect of free ammonia (FA) at the head end of the nitrification reaction zone 4 and free nitrite (FNA) in the circulating mixed solution on nitrate bacteria (NOB) is fully utilized, which is conducive to the device to stably maintain the nitrification reaction zone 4 in the nitrification stage.

[0118] Although the above text takes the three-stage anaerobic ammonium oxidation reaction partition (divided into 6 anaerobic ammonium oxidation reaction sections) as an example for exemplary introduction, the present invention is not limited to this, and it can have multiple-stage anaerobic ammonium oxidation reaction partitions, such as two-stage anaerobic ammonium oxidation reaction partitions (divided into 4 anaerobic ammonium oxidation reaction sections), four-stage anaerobic ammonium oxidation reaction partitions (divided into 8 anaerobic ammonium oxidation reaction sections), five-stage anaerobic ammonium oxidation reaction partitions (divided into 10 anaerobic ammonium oxidation reaction sections), etc., as long as the nitrification mixed liquor can be treated to meet the preset indicators.

[0119] In some embodiments, the high-ammonia-nitrogen and low-COD wastewater denitrification treatment device further includes: a submerged plug flow pump 6;

[0120] A bottom communicating hole is provided between each of the anaerobic ammonium oxidation reaction sections and the nitrification reaction zone 4;

[0121] A submerged plug flow pump 6 is provided in the bottom communicating hole;

[0122] The water flow angle θ between the water outlet direction of the submerged plug flow pump 6 and the flow direction of the nitrification mixed liquid in the nitrification reaction zone 4 is between 0° and 180°; wherein, when the water outlet direction of the submerged plug flow pump 6 is the same as the flow direction of the nitrification mixed liquid in the nitrification reaction zone 4, the water flow angle θ is 0°; when the water outlet direction of the submerged plug flow pump 6 is opposite to the flow direction of the nitrification mixed liquid in the nitrification reaction zone 4, the water flow angle θ is 180°;

[0123] Specifically, a first submerged plug flow pump 6-1 is provided in the bottom communicating hole between the first anaerobic ammonium oxidation reaction section 3-1 and the nitrification reaction zone 4; a second submerged plug flow pump 6-2 is provided in the bottom communicating hole between the second anaerobic ammonium oxidation reaction section 3-2 and the nitrification reaction zone 4; a third submerged plug flow pump 6-3 is provided in the bottom communicating hole between the third anaerobic ammonium oxidation reaction section 3-3 and the nitrification reaction zone 4; a fourth submerged plug flow pump 6-4 is provided in the bottom communicating hole between the fourth anaerobic ammonium oxidation reaction section 3-4 and the nitrification reaction zone 4; a fifth submerged plug flow pump 6-5 is provided in the bottom communicating hole between the fifth anaerobic ammonium oxidation reaction section 3-5 and the nitrification reaction zone 4; a sixth submerged plug flow pump 6-6 is provided in the bottom communicating hole between the sixth anaerobic ammonium oxidation reaction section 3-6 and the nitrification reaction zone 4;

[0124] Each of the submersible plug flow pumps 6 is connected to a control system.

[0125] Preferably, the submersible plug flow pump 6 is arranged at an upstream position of the anaerobic ammonium oxidation reaction section, that is, close to the water inlet end of the nitrification reaction zone 4 .

[0126] Preferably, the water flow angle θ is between 20° and 80° or between 100° and 170°.

[0127] The submerged plug flow pump 6 can not only adjust the amount of treated water in the anaerobic ammonium oxidation reaction zone 3, but also provide power for the flow and mixing of the mixed liquid in the nitrification reaction zone 4. According to the online monitoring data, the flow rate of the submerged plug flow pump 6 is increased or decreased to ensure that the nitrite nitrogen is completely removed when the supernatant passes through the anaerobic ammonium oxidation reaction zone 3. The flow pattern of the mixed liquid in the nitrification reaction zone 4 is changed by adjusting the water flow angle θ of the submerged plug flow pump 6 on the same side, such as adjusting the water flow angle θ of the first submerged plug flow pump 6-1, the third submerged plug flow pump 6-3, and the fifth submerged plug flow pump 6-5 to 20° to 80°, and the water flow angle θ of the second submerged plug flow pump 6-2, the fourth submerged plug flow pump 6-4, and the sixth submerged plug flow pump 6-6 to 100° to 170°, the mixed liquid in the nitrification reaction zone 4 can form a circulating flow pattern.

[0128] like Figure 2 As shown, in some embodiments, the mixed liquid solid-liquid separation system 5 includes a diversion area 5-7, a mud bucket 5-8, a sedimentation area 5-9 and a clear water area 5-10;

[0129] The multiple mixed liquid solid-liquid separation systems 5 are arranged in the nitrification reaction zone 4 of the biological denitrification system, and are adjacent to the downstream of the anaerobic ammonium oxidation reaction section, and the nitrified sludge of the mixed liquid solid-liquid separation system 5 corresponding to the anaerobic ammonium oxidation reaction section freely settles back into the nitrification reaction zone 4, and the supernatant enters the anaerobic ammonium oxidation reaction section; specifically, the first mixed liquid solid-liquid separation system 5-1, the second mixed liquid solid-liquid separation system 5-2, the third mixed liquid solid-liquid separation system 5-3, the fourth mixed liquid solid-liquid separation system 5-4, the fifth mixed liquid solid-liquid separation system 5-5, and the sixth mixed liquid solid-liquid separation system 5-6 are respectively arranged at the downstream position (i.e., close to one end of the terminal anaerobic ammonium oxidation reaction zone 7) of the corresponding first anaerobic ammonium oxidation reaction section 3-1, the second anaerobic ammonium oxidation reaction section 3-2, the third anaerobic ammonium oxidation reaction section 3-3, the fourth anaerobic ammonium oxidation reaction section 3-4, the fifth anaerobic ammonium oxidation reaction section 3-5, and the sixth anaerobic ammonium oxidation reaction section 3-6.

[0130] The upper end of the diversion zone 5-7 is the water inlet end, connected to the nitrification reaction zone 4, and the lower end is connected to the precipitation zone 5-9; the diversion zone 5-7 and the clear water zone 5-10 are separated by a partition;

[0131] The sedimentation area 5-9 is located above the mud bucket 5-8 and below the clear water area 5-10;

[0132] The upper end of the clean water zone 5-10 is the water outlet, which is connected to the anaerobic ammonium oxidation reaction section;

[0133] The mud outlet at the bottom of the mud hopper 5-8 is connected to the nitrification reaction zone 4.

[0134] like Figure 2 As shown, the mixed liquid solid-liquid separation system 5: the nitrified mixed liquid in the nitrification reaction zone 4 enters the diversion zone 5-7 from the upper end of the mixed liquid solid-liquid separation system 5, and then enters the sedimentation zone 5-9 to separate the nitrified mixed liquid into a supernatant and nitrified sludge. The supernatant enters the clear water zone 5-10, and then enters the anaerobic ammonium oxidation reaction zone 3 from the upper end of the clear water zone 5-10, and the nitrified sludge enters the mud hopper 5-8, and then freely falls back to the nitrification reaction zone 4 through the reflux seam.

[0135] The diversion area 5-7 is used to stabilize the flow state of the mixed liquid and reduce the impact on the clear water area 5-10 and the sedimentation area 5-9;

[0136] Mud hoppers 5-8 are used to store concentrated and separated nitrified sludge;

[0137] Sedimentation zones 5-9 are used to clarify the nitrification mixed liquor to form supernatant and nitrification sludge;

[0138] The clear water areas 5-10 are used to store the supernatant.

[0139] In some embodiments, the aeration system includes a fan 8, a first solenoid valve 9-1, a second solenoid valve 9-2, a third solenoid valve 9-3, a first aeration device 10-1, a second aeration device 10-2, and a third aeration device 10-3;

[0140] The fan 8, the first solenoid valve 9-1, the second solenoid valve 9-2, and the third solenoid valve 9-3 are respectively connected to the control system;

[0141] The fan 8 is connected to the first solenoid valve 9-1, the second solenoid valve 9-2 and the third solenoid valve 9-3 respectively;

[0142] The first solenoid valve 9-1 is connected to the first aeration device 10-1;

[0143] The second solenoid valve 9-2 is connected to the second aeration device 10-2;

[0144] The third solenoid valve 9-3 is connected to the third aeration device 10-3;

[0145] The first aeration device 10 - 1 , the second aeration device 10 - 2 and the third aeration device 10 - 3 are respectively arranged in the nitrification reaction zone 4 at intervals.

[0146] A fan 8 is used to provide the air volume required for aeration;

[0147] Solenoid valve, used to adjust the gas supply;

[0148] Aeration equipment used to disperse air into the mixed liquid in the form of fine bubbles.

[0149] Among them, the aeration equipment adopts a universal aeration head or a perforated tube or a micro-nano bubble aerator.

[0150] There are two aeration modes for the nitrification reaction zone 4: gradual aeration and intermittent aeration. The dissolved oxygen in the nitrification reaction zone 4 is gradually reduced from 3.5 mg / L to about 0 mg / L. There are three water inlet modes: continuous inlet at the head end, intermittent inlet, and / or multi-point inlet along the way.

[0151] The aeration system provides air or oxygen to the nitrification reaction zone 4, provides DO to the nitrification reaction zone 4, and adopts a decreasing aeration or intermittent aeration mode.

[0152] In some embodiments, the dosing system includes a liquid medicine tank 18, a dosing pump 11, a second liquid level meter 2-2 and an agitator;

[0153] The liquid medicine tank 18 is provided with a second liquid level gauge 2-2 and a stirrer;

[0154] One end of the dosing pump 11 is connected to the liquid medicine tank 18, and the other end is connected to the nitrification reaction zone 4 of the biological denitrification system;

[0155] The dosing pump 11 and the second liquid level meter 2 - 2 are respectively connected to the control system.

[0156] The dosing system provides liquid medicine to adjust the pH value of the nitrification reaction zone 4 to be within an appropriate range.

[0157] In some embodiments, the sedimentation concentration and return system includes a sedimentation concentration tank 19, a sludge return pump 14, a water outlet 15 and a sludge discharge pipe 16;

[0158] The water inlet of the sedimentation and concentration tank 19 is connected to the water outlet of the terminal anaerobic ammonia oxidation reaction zone 7;

[0159] The sedimentation and concentration tank 19 is provided with a water outlet 15 and a sludge outlet;

[0160] The sludge outlet is connected to the feed end of the sludge return pump 14 and the sludge discharge pipe 16 respectively;

[0161] The discharge end of the sludge reflux pump 14 is connected to the nitrification reaction zone 4;

[0162] The sludge return pump 14 is connected to a control system.

[0163] In the sedimentation, concentration and reflux system, solid-liquid separation, tail water discharge, sludge reflux and discharge are completed.

[0164] In some embodiments, the control system includes online monitoring instruments 12 and a PLC control cabinet 13;

[0165] The online monitoring instrument 12 includes a plurality of online multi-parameter monitoring probes;

[0166] A plurality of online multi-parameter monitoring probes are respectively arranged at a plurality of monitoring points in the anaerobic ammonium oxidation reaction section and the nitrification reaction zone 4, and are respectively connected to the online monitoring instrument 12. Specifically, the first online multi-parameter monitoring probe 12-1 is arranged in the first anaerobic ammonium oxidation reaction section 3-1, the second online multi-parameter monitoring probe 12-2 is arranged in the second anaerobic ammonium oxidation reaction section 3-2, the third online multi-parameter monitoring probe 12-3 is arranged in the third anaerobic ammonium oxidation reaction section 3-3, the fourth online multi-parameter monitoring probe 12-4 is arranged in the fourth anaerobic ammonium oxidation reaction section 3-4, the fifth online multi-parameter monitoring probe 12-5 is arranged in the fifth anaerobic ammonium oxidation reaction section 3-5, the sixth online multi-parameter monitoring probe 12-6 is arranged in the sixth anaerobic ammonium oxidation reaction section 3-6, the seventh online multi-parameter monitoring probe 12-7, the eighth online multi-parameter monitoring probe 12-8, and the ninth online multi-parameter monitoring probe 12-9 are arranged at intervals at the monitoring points in the nitrification reaction zone 4.

[0167] The PLC control cabinet 13 is respectively connected to the water inlet pump 1, the first liquid level gauge 2-1, the second liquid level gauge 2-2, the third liquid level gauge 2-3, the first submerged plug flow pump 6-1, the second submerged plug flow pump 6-2, the third submerged plug flow pump 6-3, the fourth submerged plug flow pump 6-4, the fifth submerged plug flow pump 6-5, the sixth submerged plug flow pump 6-6, the fan 8, the first solenoid valve 9-1, the second solenoid valve 9-2, the third solenoid valve 9-3, the dosing pump 11, the online monitoring instrument 12 and the sludge return pump 14.

[0168] The online monitoring instrument 12 is used to monitor parameters such as dissolved oxygen DO, pH, redox potential ORP, temperature, conductivity, ammonia nitrogen concentration, flow rate, liquid level, etc., and upload the monitoring data to the control system; among them, DO, pH, redox potential ORP, temperature, and conductivity can be monitored by online multi-parameter monitoring probes, ammonia nitrogen concentration is monitored by an ammonia nitrogen online automatic monitoring instrument, flow rate is monitored by a flow meter, and liquid level is monitored by a liquid level meter, and the above monitoring data are all uploaded to the control system.

[0169] The PLC control cabinet 13 is used to adjust and control the operating conditions of the aeration system, the dosing system, the submersible flow pump 6, and the sludge return pump 14 according to preset (and / or editable) parameters to ensure stable operation of the device.

[0170] According to the reaction conditions in the anaerobic ammonium oxidation reaction zone 3, the control system controls the flow of the submerged plug flow pump 6 to adjust the reflux flow between nitrification and anaerobic ammonium oxidation to achieve efficient performance of the above two reactions, with a reflux ratio of R = 0 to 300%.

[0171] The control system can adjust the aeration system to change the dissolved oxygen concentration, adjust the submerged flow pump 6 to change the reflux ratio of the nitrification mixture, and adjust the dosing system to maintain an appropriate pH value based on online monitoring data such as DO, pH, redox potential ORP, temperature, conductivity, ammonia nitrogen concentration, flow, and liquid level.

[0172] Based on the above-mentioned high-ammonia-nitrogen and low-COD wastewater denitrification treatment device, the present invention also discloses a high-ammonia-nitrogen and low-COD wastewater denitrification treatment method, comprising the following steps:

[0173] The high-ammonia-nitrogen and low-COD wastewater that has been pretreated by turbidity removal and pH adjustment first enters the nitrification reaction zone 4 for partial nitrification reaction. Under aerobic conditions, part of the ammonia nitrogen in the high-ammonia-nitrogen and low-COD wastewater is oxidized into nitrite nitrogen, and a nitrification mixed liquid containing residual ammonia nitrogen and newly generated nitrite nitrogen is formed; the operating parameters DO, pH and temperature of the nitrification reaction section are controlled within the set range through the control system;

[0174] The nitrification mixed liquid simultaneously / separately enters the mixed liquid solid-liquid separation system 5 for solid-liquid separation, and the nitrification mixed liquid is separated into supernatant and nitrification sludge;

[0175] The nitrified sludge settles freely and falls back to the nitrification reaction zone 4, and the supernatant enters the anaerobic ammonium oxidation reaction section for anaerobic ammonium oxidation denitrification reaction. The nitrite nitrogen and part of the ammonia nitrogen in the supernatant are removed by the anaerobic ammonium oxidation reaction. The denitrified supernatant is refluxed to the nitrification reaction zone 4 through the submerged plug flow pump 6, and the remaining ammonia nitrogen continues to undergo nitrification reaction. The speed of the submerged plug flow pump 6 in the anaerobic ammonium oxidation reaction section is controlled within a set range by the control system to ensure a suitable reflux ratio;

[0176] The nitrification mixed liquid undergoes multiple anaerobic ammonium oxidation denitrification reactions in multiple parallel anaerobic ammonium oxidation reaction sections;

[0177] When the high-ammonia-nitrogen and low-COD wastewater reaches the end of the nitrification reaction zone 4 after multiple denitrification treatments, the ammonia-nitrogen concentration of the nitrification mixed liquid is ≤20 mg / L. The nitrification mixed liquid enters the terminal anaerobic ammonia oxidation reaction zone 7 for anaerobic ammonia oxidation denitrification treatment to complete further deep denitrification.

[0178] The nitrification mixed liquid after deep denitrification treatment enters the sedimentation concentration and reflux system, the sludge separated by sedimentation is returned to the nitrification reaction zone 4 by the sludge reflux pump 14 or discharged by the sludge discharge pipe 16, and the separated clean water is discharged by the outlet 15; the terminal control parameters of the nitrification reaction zone 4 are: DO = 0 ~ 0.5 mg / L, pH = 7.5 ~ 8.2.

[0179] The flow pattern of the nitrification mixed liquid in the nitrification reaction zone 4 is a plug flow mode, a circulation mode or other different flow patterns.

[0180] Example 1

[0181] This embodiment takes the rare earth tail water three-stage circulation denitrification device as an example, and uses high ammonia nitrogen and low COD wastewater that has been pretreated by turbidity removal and pH adjustment as raw water, with an ammonia nitrogen concentration of 150-230 mg / L, pH=7.6-8.5, suspended solids SS≤20 mg / L, and COD=10-50 mg / L.

[0182] Control conditions of the wastewater denitrification treatment device: Nitrification reaction zone 4: DO = 0 ~ 3.5 mg / L (and gradually decreases from 3.5 mg / L to 0 along the way), total hydraulic retention time HRT = 4.0 ~ 6.0h, mixed liquid suspended solids concentration MLSS = 2000 ~ 4200mg / L, nitrification mixed liquid flow mode. Anaerobic ammonia oxidation reaction zone 3: DO ≤ 0.5mg / L, total hydraulic retention time HRT = 4.0 ~ 6.0h, the water flow angle θ of the submerged plug flow pump 6 on both sides is 20 ° ~ 60 °. Terminal anaerobic ammonia oxidation reaction zone 7: DO ≤ 0.5mg / L, HRT = 1.0 ~ 2.0h, sludge sedimentation time 2.0h.

[0183] The pretreated rare earth tail water is sent to the nitrification reaction zone 4 by the water inlet system for limited nitrification reaction, and part of the ammonia nitrogen in the tail water is converted into nitrite nitrogen to form a tail water mixture containing nitrite nitrogen and ammonia nitrogen. The control conditions are: DO = 1.5 ~ 3.5 mg / L, HRT = 4.0 ~ 6.0h, MLSS = 2600 ~ 4200 mg / L. A part of the tailwater nitrification mixed liquid enters the middle section of the nitrification reaction zone 4 to continue the nitrification reaction, and the other part of the tailwater nitrification mixed liquid is separated by the first mixed liquid solid-liquid separation system 5-1 and the second mixed liquid solid-liquid separation system 5-2. The sludge falls directly back to the nitrification reaction zone 4, and the supernatant enters the first anaerobic ammonia oxidation reaction section 3-1 and the second anaerobic ammonia oxidation reaction section 3-2 for anaerobic ammonia oxidation denitrification reaction, mainly removing most of the nitrite nitrogen and part of the ammonia nitrogen. The control conditions of the anaerobic ammonia oxidation reaction section are: DO = 0.2 ~ 0.5mg / L, HRT = 1.5 ~ 2.0h. The treated nitrification mixed liquid is refluxed to the nitrification reaction zone 4 by the first submerged plug flow pump 6-1 and the second submerged plug flow pump 6-2 to continue the nitrification reaction, and the denitrification treatment is circulated in this way, and the reflux ratio R = 0 ~ 150%.

[0184] The tailwater nitrification mixed liquid entering the middle section of the nitrification reaction zone 4 continues to undergo nitrification reaction, and the control conditions are: DO = 0.8 ~ 1.8 mg / L, HRT = 1.5 ~ 2.0 h, MLSS = 3100 ~ 4000 mg / L. A part of the tailwater nitrification mixed liquid enters the end of the nitrification reaction zone 4, and the other part of the tailwater nitrification mixed liquid is separated from the mud and water by the third mixed liquid solid-liquid separation system 5-3 and the fourth mixed liquid solid-liquid separation system 5-4, and the sludge falls directly back to the middle section of the nitrification reaction zone 4, and the supernatant enters the third anaerobic ammonium oxidation reaction section 3-3 and the fourth anaerobic ammonium oxidation reaction section 3-4 for anaerobic ammonium oxidation denitrification reaction, and the control conditions are: DO = 0.4 ~ 0.6 mg / L, HRT = 1.5 ~ 2.0 h. The treated nitrification mixed liquid is refluxed to the nitrification reaction zone 4 by the third submerged plug flow pump 6-3 and the fourth submerged plug flow pump 6-4 for nitrification reaction, and the cyclic denitrification treatment is carried out in this way, with the reflux ratio R=100-300%.

[0185] The tailwater nitrification mixed liquid entering the end of the nitrification reaction zone 4 continues to undergo nitrification reaction, and the control conditions are: DO = 0.2 ~ 0.8 mg / L, HRT = 1.5 ~ 2.0h, MLSS = 2600 ~ 3000 mg / L. A part of the nitrification liquid enters the terminal anaerobic ammonium oxidation reaction zone 7 for further deep denitrification and then enters the precipitation concentration and reflux system, and a part of the nitrification liquid is separated from the mud by the fifth mixed liquid solid-liquid separation system 5-5 and the sixth mixed liquid solid-liquid separation system 5-6, and the sludge falls directly back to the end of the nitrification reaction zone 4, and the supernatant enters the fifth anaerobic ammonium oxidation reaction section 3-5 and the sixth anaerobic ammonium oxidation reaction section 3-6 for anaerobic ammonium oxidation denitrification reaction, and the control conditions are: DO = 0 ~ 0.5 mg / L, HRT = 1.5 ~ 2.0h. The treated nitrification mixed liquid is refluxed to the end of the nitrification reaction zone 4 by the fifth submerged plug flow pump 6-5 and the sixth submerged plug flow pump 6-6 for cyclic denitrification treatment, with a reflux ratio of R=50-150%.

[0186] The tail water nitrification mixed liquid entering the precipitation concentration and reflux system is separated into solid and liquid, and the supernatant after denitrification treatment is discharged, completing the rare earth tail water denitrification treatment and solid-liquid separation process, and the precipitation time is 2.0h. The effluent ammonia nitrogen ≤12.4mg / L, total nitrogen ≤28.7mg / L, SS ≤30mg / L, meeting the requirements of the "Rare Earth Industry Pollutant Emission Standard" (GB26451-2011).

[0187] Example 2

[0188] This embodiment still takes the rare earth tail water three-stage cycle denitrification device as an example, and uses artificial simulated rare earth tail water as raw water, with ammonia nitrogen concentration of 75-120 mg / L, pH=8.3-8.5, turbidity ≤5NTU, COD≤20 mg / L. Control conditions of the wastewater denitrification treatment device: nitrification reaction zone 4: DO=0.2-1.5 mg / L, total hydraulic retention time HRT=6.0h, mixed liquid suspended solids concentration MLSS=2000-3600 mg / L, nitrification mixed liquid flow state is a circulation mode. Anaerobic ammonia oxidation reaction zone 3: DO≤0.5 mg / L, total hydraulic retention time HRT=6.0h, the water flow angle θ of the submerged plug flow pump 6 on one side is 20°~60°, and the water flow angle θ on the other side is 120°~170°. Terminal anaerobic ammonia oxidation reaction zone 7: DO≤0.5 mg / L, HRT=2.0h, precipitation concentration time 2.0h.

[0189] The simulated rare earth tail water is sent from the water inlet system to the front section of the nitrification reaction zone 4 for partial nitrification reaction to form a tail water nitrification mixed liquid containing nitrite nitrogen and ammonia nitrogen, and the control conditions are: DO = 1.5 ~ 2.5 mg / L, HRT = 2.0h, MLSS = 3300 ~ 4200 mg / L. A part of the tail water nitrification mixed liquid enters the middle section of the nitrification reaction zone 4 to continue the nitrification reaction, and the other part of the tail water nitrification mixed liquid is separated by mud and water through the first mixed liquid solid-liquid separation system 5-1 and the second mixed liquid solid-liquid separation system 5-2, and the sludge falls directly back to the nitrification reaction zone 4, and the supernatant enters the first anaerobic ammonia oxidation reaction section 3-1 and the second anaerobic ammonia oxidation reaction section 3-2 for anaerobic ammonia oxidation denitrification reaction, mainly removing most of the nitrite nitrogen and part of the ammonia nitrogen, and the control conditions are: DO = 0.3 ~ 0.5 mg / L, HRT = 2.0h. The treated nitrification mixed liquid is refluxed to the nitrification reaction zone 4 by the first submerged plug flow pump 6-1 and the second submerged plug flow pump 6-2 to continue the nitrification reaction, and the denitrification treatment is carried out in this way, with the reflux ratio R=0-100%.

[0190] The tailwater nitrification mixed liquid entering the middle section of the nitrification reaction zone 4 continues to undergo nitrification reaction, and the control conditions are: DO = 0.6 ~ 1.2 mg / L, HRT = 2.0h, MLSS = 2000 ~ 4000 mg / L. A part of the tailwater nitrification mixed liquid enters the end of the nitrification reaction zone 4, and the other part of the tailwater nitrification mixed liquid is separated by the third mixed liquid solid-liquid separation system 5-3 and the fourth mixed liquid solid-liquid separation system 5-4. The sludge falls directly back to the middle section of the nitrification reaction zone 4, and the supernatant enters the third anaerobic ammonium oxidation reaction section 3-3 and the fourth anaerobic ammonium oxidation reaction section 3-4 for anaerobic ammonium oxidation denitrification reaction, and the control conditions are: DO = 0.4 ~ 0.6 mg / L, HRT = 2.0h. The treated nitrification mixed liquid is refluxed to the nitrification reaction zone 4 by the third submerged plug flow pump 6-3 and the fourth submerged plug flow pump 6-4 for nitrification reaction, and the cyclic denitrification treatment is carried out, and the reflux ratio R = 100 ~ 180%.

[0191] The tailwater nitrification mixed liquid entering the end of the nitrification reaction zone 4 continues to undergo nitrification reaction, and the control conditions are: DO = 0.2 ~ 0.8 mg / L, HRT = 2.0h, MLSS = 2000 ~ 4000 mg / L. A part of the nitrification liquid enters the terminal anaerobic ammonium oxidation reaction zone 7 for further deep denitrification and then enters the precipitation concentration and reflux system. A part of the nitrification liquid is separated from the mud by the fifth mixed liquid solid-liquid separation system 5-5 and the sixth mixed liquid solid-liquid separation system 5-6, and the sludge falls directly back to the end of the nitrification reaction zone 4. The supernatant enters the fifth anaerobic ammonium oxidation reaction section 3-5 and the sixth anaerobic ammonium oxidation reaction section 3-6 for anaerobic ammonium oxidation denitrification reaction, and the control conditions are: DO = 0.2 ~ 0.5 mg / L, HRT = 2.0h. The treated nitrification mixed liquid is refluxed to the end of the nitrification reaction zone 4 by the fifth submerged plug flow pump 6-5 and the sixth submerged plug flow pump 6-6 for cyclic denitrification treatment, with a reflux ratio of R=50-150%.

[0192] The tail water nitrification mixed liquid entering the precipitation concentration and reflux system is separated into solid and liquid, and the supernatant after denitrification treatment is discharged, completing the rare earth tail water denitrification treatment and solid-liquid separation process, and the precipitation concentration time is 2.0h. The effluent ammonia nitrogen ≤7.2mg / L, total nitrogen ≤26.8mg / L, SS ≤20mg / L, meeting the requirements of the "Rare Earth Industry Pollutant Emission Standard" (GB26451-2011).

[0193] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-ammonia-nitrogen and low-COD wastewater denitrification treatment device, characterized in that: include: Water inlet system, biological denitrification system, aeration system, dosing system, mixed liquid solid-liquid separation system (5), sedimentation concentration and reflux system and control system; The water inlet system is connected to the biological denitrification system; The mixed liquid solid-liquid separation system (5) is arranged in the biological denitrification system; The aeration system is connected to the biological denitrification system; The dosing system is connected to the biological denitrification system; The water inlet of the precipitation concentration and reflux system is connected to the water outlet of the biological denitrification system; The control system is respectively connected with the sedimentation concentration and reflux system, the water inlet system, the biological denitrification system, the aeration system and the dosing system.

2. The high-ammonia-nitrogen and low-COD wastewater denitrification treatment device according to claim 1 is characterized in that: The water inlet system comprises: a water tank (17), a water inlet pump (1) and a first liquid level meter (2-1); A first liquid level meter (2-1) is arranged in the water tank (17); The water inlet end of the water inlet pump (1) is connected to the water tank (17), and the water outlet end is connected to the biological denitrification system; The water inlet pump (1) and the first liquid level meter (2-1) are respectively connected to a control system.

3. The high ammonia nitrogen and low COD wastewater denitrification treatment device according to claim 2 is characterized in that: The biological denitrification system comprises an anaerobic ammonium oxidation reaction zone (3), a nitrification reaction zone (4) and a terminal anaerobic ammonium oxidation reaction zone (7); The anaerobic ammonium oxidation reaction zone (3) is arranged on both sides of the nitrification reaction zone (4), and the two are connected; The anaerobic ammonium oxidation reaction zone (3) is divided into a plurality of independent anaerobic ammonium oxidation reaction sections connected in parallel by a partition, and the anaerobic ammonium oxidation reaction sections are all connected to the nitrification reaction zone (4); The water outlet of the nitrification reaction zone (4) is connected to the terminal anaerobic ammonia oxidation reaction zone (7), and the water inlet is connected to the water outlet of the water inlet pump (1); A third liquid level meter (2-3) is provided in the terminal anaerobic ammonium oxidation reaction zone (7); The third liquid level meter (2-3) is connected to the control system.

4. The high-ammonia-nitrogen and low-COD wastewater denitrification treatment device according to claim 3 is characterized in that: Also includes: Submersible plug flow pump (6); A bottom communication hole is provided between each of the anaerobic ammonium oxidation reaction sections and the nitrification reaction zone (4); A submersible plug flow pump (6) is provided in the bottom communicating hole; The water flow angle θ between the water outlet direction of the submerged plug flow pump (6) and the flow direction of the nitrification mixed liquid in the nitrification reaction zone (4) is between 0° and 180°; The submerged plug flow pump (6) is connected to a control system.

5. The high ammonia nitrogen and low COD wastewater denitrification treatment device according to claim 3 is characterized in that: The mixed liquid solid-liquid separation system (5) comprises a diversion area (5-7), a mud bucket (5-8), a sedimentation area (5-9) and a clear water area (5-10); A plurality of the mixed liquid solid-liquid separation systems (5) are arranged in the nitrification reaction zone (4) of the biological denitrification system, and each of the mixed liquid solid-liquid separation systems (5) corresponds to an anaerobic ammonium oxidation reaction section; The upper end of the diversion zone (5-7) is a water inlet end connected to the nitrification reaction zone (4), and the lower end is connected to the precipitation zone (5-9); The sedimentation area (5-9) is located above the mud bucket (5-8) and below the clear water area (5-10); The upper end of the clean water zone (5-10) is a water outlet, which is connected to the anaerobic ammonium oxidation reaction section; The mud outlet at the bottom of the mud hopper (5-8) is connected to the nitrification reaction zone (4).

6. The high-ammonia-nitrogen and low-COD wastewater denitrification treatment device according to claim 3 is characterized in that: The aeration system comprises a fan (8), a solenoid valve and an aeration device; The fan (8) and the solenoid valve are respectively connected to a control system; The fan (8) is respectively connected to a plurality of solenoid valves; The solenoid valve is connected to the aeration equipment; The plurality of aeration devices are arranged at intervals in the nitrification reaction zone (4).

7. The high-ammonia-nitrogen and low-COD wastewater denitrification treatment device according to claim 1 is characterized in that: The dosing system comprises a drug liquid tank (18), a drug dosing pump (11), a second liquid level meter (2-2) and a stirrer; The liquid medicine tank (18) is provided with a second liquid level meter (2-2) and a stirrer; One end of the dosing pump (11) is connected to the drug liquid tank (18), and the other end is connected to the biological denitrification system; The dosing pump (11) and the second liquid level meter (2-2) are respectively connected to a control system.

8. The high-ammonia-nitrogen and low-COD wastewater denitrification treatment device according to claim 3 is characterized in that: The sedimentation, concentration and reflux system comprises a sedimentation and concentration tank (19), a sludge reflux pump (14), a water outlet (15) and a sludge discharge pipe (16); The water inlet of the sedimentation and concentration tank (19) is connected to the water outlet of the terminal anaerobic ammonium oxidation reaction zone (7); The sedimentation and concentration tank (19) is provided with a water outlet (15) and a sludge outlet; The sludge outlet is connected to the feed end of the sludge return pump (14) and the sludge discharge pipe (16) respectively; The discharge end of the sludge reflux pump (14) is connected to the nitrification reaction zone (4); The sludge return pump (14) is connected to a control system.

9. The high-ammonia-nitrogen and low-COD wastewater denitrification treatment device according to claim 3 is characterized in that: The control system comprises an online monitoring instrument (12) and a PLC control cabinet (13); The online monitoring instrument (12) comprises a plurality of online multi-parameter monitoring probes; A plurality of the online multi-parameter monitoring probes are respectively arranged in a plurality of anaerobic ammonium oxidation reaction sections and nitrification reaction zones (4), and are respectively connected to online monitoring instruments (12); The online monitoring instrument (12) is connected to a PLC control cabinet (13).

10. A method for treating wastewater denitrification based on the high-ammonia-nitrogen and low-COD wastewater denitrification treatment device according to any one of claims 1 to 9, characterized in that: The following steps are involved: The high-ammonia-nitrogen and low-COD wastewater first enters the nitrification reaction zone (4) for partial nitrification reaction, oxidizing part of the ammonia nitrogen in the high-ammonia-nitrogen and low-COD wastewater into nitrite nitrogen, and forming a nitrification mixed liquid containing residual ammonia nitrogen and newly generated nitrite nitrogen; The nitrification mixed liquid simultaneously / separately enters the mixed liquid solid-liquid separation system (5) for solid-liquid separation, and the nitrification mixed liquid is separated into a supernatant and nitrification sludge; The nitrified sludge is freely settled back to the nitrification reaction zone (4), and the supernatant enters the anaerobic ammonium oxidation reaction section for anaerobic ammonium oxidation denitrification reaction, removing all nitrite nitrogen and part of ammonia nitrogen in the supernatant. The denitrified supernatant is returned to the nitrification reaction zone (4) through a submerged plug flow pump (6), and the remaining ammonia nitrogen continues to undergo nitrification reaction; The nitrification mixed liquid undergoes multiple anaerobic ammonium oxidation denitrification reactions in multiple parallel anaerobic ammonium oxidation reaction sections; When the high-ammonia-nitrogen and low-COD wastewater reaches the end of the nitrification reaction zone (4) after multiple denitrification treatments, the ammonia-nitrogen concentration of the nitrification mixed liquid is ≤20 mg / L. The nitrification mixed liquid enters the terminal anaerobic ammonium oxidation reaction zone (7) for anaerobic ammonium oxidation denitrification treatment to complete further deep denitrification. The nitrification mixed liquid after deep denitrification treatment enters the sedimentation concentration and reflux system, the sludge separated by sedimentation is refluxed to the nitrification reaction zone (4) by the sludge reflux pump (14) or discharged from the sludge discharge pipe (16), and the separated clean water is discharged from the water outlet (15); the terminal control parameters of the nitrification reaction zone (4) are: DO = 0 ~ 0.5 mg / L, pH = 7.5 ~ 8.

2.

11. The method for treating wastewater by denitrification according to claim 10, characterized in that: The control system of the nitrification reaction zone (4) adjusts the oxygen supply and dosage of the aeration system according to the monitoring data of the dissolved oxygen DO and pH value of the nitrification reaction zone (4); Control parameters: DO = 0 ~ 3.5 mg / L, pH = 7.2 ~ 9.5, mixed liquor suspended solids concentration MLSS = 2000 ~ 6000 mg / L, hydraulic retention time HRT = 4 ~ 8h.

12. The method for treating wastewater by denitrification according to claim 10, characterized in that: The reflux ratio R of the nitration mixed solution is 0-300%.

13. The method for treating wastewater by denitrification according to claim 10, characterized in that: The control parameters of each anaerobic ammonium oxidation reaction section are: DO≤0.5mg / L, pH=7.0-8.5, HRT=1.0-3.0h.

14. The method for treating wastewater by denitrification according to claim 10, characterized in that: The flow state of the nitration mixed liquid in the nitration reaction zone (4) is a plug flow mode or a circulation mode.

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