Device for advanced denitrification treatment of refractory wastewater coupled with ozonation

Abstract

The application discloses a device for deep denitrification treatment of refractory sewage coupled with ozone oxidation, which comprises a primary denitrification tank, a secondary denitrification tank, a primary ozone oxidation tank, an intermediate water tank, a secondary ozone oxidation tank, a degassing tank, a primary nitrification tank, a secondary nitrification tank and a water outlet supervision tank which are sequentially connected, wherein a water inlet is arranged on the primary denitrification tank; an intermediate water tank backflow port is arranged at the bottom of the intermediate water tank and is communicated with the primary denitrification tank through a pump and a pipeline; a primary nitrification tank backflow port is arranged at the bottom of the primary nitrification tank and is communicated with the secondary ozone oxidation tank through a pump and a pipeline; and a secondary nitrification tank backflow port is arranged at the bottom of the secondary nitrification tank and is communicated with the primary denitrification tank through a pump and a pipeline. The device can guarantee the ammonia nitrogen removal effect of the effluent, reduce the ozone dosage and the system operation cost, and reduce the investment cost and the land occupation.

Description

Technical Field

[0001] This utility model relates to the field of deep treatment technology for industrial wastewater, and in particular to a deep denitrification treatment device for recalcitrant wastewater using an integrated baffle structure coupled with ozone oxidation. Through the synergistic effect of multi-stage A / O and gradient ozone oxidation, both ozone consumption and carbon source consumption are reduced. Background Technology

[0002] Nitrogenous pollutants in industrial wastewater, such as ammonia nitrogen, nitrate nitrogen, and organic nitrogen, as well as recalcitrant organic compounds, such as polycyclic aromatic hydrocarbons, phenols, and dye intermediates, pose a significant challenge to the field of environmental protection. With increasingly stringent emission standards (such as the Class A standard of GB 18918-2002 "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants"), traditional biological denitrification processes (such as AO, A...) are becoming increasingly difficult to implement. 2 Ozone oxidation (OO) has several limitations in treating high-nitrogen, recalcitrant wastewater: insufficient carbon sources lead to low denitrification efficiency, large sludge production, and high energy consumption. Furthermore, recalcitrant organic matter is structurally stable and has poor biodegradability, making it difficult for conventional biological methods to effectively degrade it. While advanced oxidation technologies (such as ozone oxidation and the Fenton process) can partially break down large organic molecules, they suffer from low ozone utilization and high operating costs.

[0003] Currently, ozone oxidation technology is widely used in the treatment of recalcitrant wastewater due to its advantages such as high efficiency and no secondary pollution. However, traditional ozone oxidation and biological denitrification processes often operate independently, lacking synergistic optimization. Ozone oxidation intermediates (such as small-molecule carboxylic acids) are not fully utilized as carbon sources for denitrification, resulting in limited improvement in denitrification efficiency. The separation of ozone oxidation and biological denitrification: In traditional processes, the ozone oxidation unit operates independently, and the oxidation products are not effectively utilized by denitrifying bacteria, leading to a waste of carbon sources. For example, in a coking wastewater treatment project, the BOD5 / COD ratio increased from 0.2 to 0.5 after ozone oxidation, but the denitrification tank still required additional methanol (200-300 mg / L), resulting in high operating costs.

[0004] To improve ozone utilization efficiency, improved technologies such as micro-nano bubble ozone oxidation and catalytic ozone oxidation (e.g., O3 / H2O2) have emerged in recent years. For example, labyrinthine hydraulic cutting micro-nano bubble generation technology can reduce ozone bubble particle size to below 20 μm and increase mass transfer efficiency to 98%; while online feedback control technology based on ORP (oxidation-reduction potential) can adjust the dosage of ozone and catalyst in real time according to water quality changes, reducing operating costs. However, these technologies mostly focus on the single ozone oxidation stage and have not systematically addressed the synergistic problem of ozone oxidation and biological denitrification.

[0005] Therefore, there is an urgent need to develop an integrated device that efficiently couples ozone oxidation and biological denitrification. Utility Model Content

[0006] This invention addresses the technical problems in existing industrial wastewater treatment technologies, such as poor synergy between ozone oxidation and biological denitrification processes, unstable denitrification effects, high costs of denitrification carbon sources, and large footprint. It proposes a deep denitrification treatment device for recalcitrant wastewater coupled with ozone oxidation. Its main objectives include: improving the synergy between ozone oxidation and biological denitrification, reducing energy consumption per ton of water treated; optimizing the biological denitrification pathway, reducing the cost of adding denitrification carbon sources; and achieving a compact design to reduce the device's footprint.

[0007] The technical problem to be solved by this utility model is achieved through the following technical solution:

[0008] This utility model is a deep denitrification treatment device for recalcitrant wastewater coupled with ozone oxidation. Specific technical features include: an integrated tank body formed by partitions, which, in the direction of water flow, sequentially comprises a primary denitrification tank (1), a secondary denitrification tank (2), a primary ozone oxidation tank (3), an intermediate water tank (4), a secondary ozone oxidation tank (5), a degassing tank (6), a primary nitrification tank (7), a secondary nitrification tank (8), and a monitoring tank (9).

[0009] The primary denitrification tank (1) is equipped with an inlet (10), and the monitoring tank (9) is equipped with an outlet (91);

[0010] The bottom of the intermediate water tank (4) is connected to the first-stage denitrification tank (1) via the first return pump (44), the bottom of the first-stage nitrification tank (7) is connected to the inlet of the second-stage ozone oxidation tank (5) via the second return pump (74), and the bottom of the second-stage nitrification tank (8) is connected to the first-stage denitrification tank (1) via the third return pump (84).

[0011] The ozone dosage of the primary ozone oxidation tank (3) and the secondary ozone oxidation tank (5) is 30-50 mg / L and 15-30 mg / L, respectively, and the hydraulic retention time ratio is 2:1.

[0012] Preferably, the primary denitrification tank (1) is filled with MBBR packing material (12) with a filling rate of 40%-50%; the secondary denitrification tank (2) is provided with a ceramic filter layer (12) with a thickness of 1.2-1.5m, and a backwashing system (17) is provided below the filter layer.

[0013] Preferably, ozone is added to the primary ozone oxidation tank (3) through a titanium plate diffuser (31) at the bottom of the tank; ozone is added to the secondary ozone oxidation tank (5) through a jet injector (51).

[0014] Preferably, the degassing tank (6) is equipped with a perforated aeration pipe (61) with an air-to-water ratio of 3:1-5:1.

[0015] Preferably, the primary nitrification tank (7) is filled with MBBR packing material (72) and equipped with disc aerators (71), with a filling rate of 45%-55%; the secondary nitrification tank (8) is equipped with a volcanic rock filter layer (82) with a thickness of 1.0-1.3m.

[0016] Preferably, a dissolved gas tank (44) is installed on the connecting pipe between the intermediate water tank (4) and the secondary ozone oxidation tank (5).

[0017] Compared with the prior art, the innovative points of this utility model include:

[0018] 1. Innovative layout of process equipment: The primary denitrification tank, secondary denitrification tank, primary ozone oxidation tank, intermediate water tank, secondary ozone oxidation tank, degassing tank, primary nitrification tank, secondary nitrification tank and monitoring tank are set up in sequence according to the water flow direction, forming a closed loop system of "denitrification → ozone oxidation → nitrification".

[0019] 2. The three-stage reflux system within the process unit promotes synergistic effects of ozone oxidation and biological denitrification: Reflux from the intermediate tank to the primary denitrification tank (reflux ratio 200%) reintroduces incompletely oxidized intermediate products (such as aldehydes) into the denitrification tank to replenish the carbon source; Reflux from the primary nitrification tank to the secondary ozone oxidation tank (reflux ratio 100%) utilizes the nitrite in the nitrification liquid to promote ozone catalytic oxidation (O3 / NO2). - (Path); Secondary nitrification tank → Primary denitrification tank recirculation (recirculation ratio 300%), ensuring deep nitrogen removal.

[0020] 3. Optimized ozone dosing to improve ozone utilization efficiency: The primary ozone oxidation tank uses a titanium plate microporous diffuser (bubble diameter <100μm) with an ozone dosage of 30-50mg / L, mainly degrading large molecular organic compounds (such as benzene series compounds); the secondary ozone oxidation tank uses a jet dissolved air device (dissolved air efficiency >90%) and adds H2O2 (5-10mg / L) to form an O3 / H2O2 advanced oxidation system, which targets and decomposes small molecular organic compounds (such as carboxylic acids).

[0021] 4. Combination of biological packing and filter media for dual denitrification to improve denitrification efficiency: The primary denitrification tank is filled with MBBR packing (45% filling rate), and the secondary denitrification tank uses a ceramic granule filter media layer (1.2m thick) to form a "biofilm-filtration" dual denitrification process; the primary nitrification tank is equipped with MBBR packing + disc aerator (DO = 2-4mg / L), and the secondary nitrification tank uses volcanic rock filter media (1.0m thick) to enhance ammonia nitrogen conversion and SS retention.

[0022] 5. Integrated structural design: Each functional unit is separated by vertical partitions, and water flows through the bottom through-holes to avoid external pipelines; Intelligent control system: Based on online monitoring of ORP and DO, the ozone dosage and reflux ratio are dynamically adjusted (e.g., when ORP>300mV, the ozone dosage is reduced by one level).

[0023] This invention has the following significant advantages over the prior art:

[0024] 1. Improved nitrogen removal efficiency: By using ozone oxidation products (small molecule organic matter) as a carbon source for denitrification, the total nitrogen removal rate is increased from 60-70% in traditional processes to over 80%.

[0025] 2. Reduced ozone consumption: Staged dosing and jet dissolved air technology enable ozone utilization rate to reach over 85%, reducing ozone consumption per ton of water from 2.6 kg / kg COD to 1.8 kg / kg COD;

[0026] 3. Strong resistance to load shocks: The MBBR combined with filter media process can operate stably within the COD / NH3-N ratio range of 2-10 (effluent TN<15mg / L);

[0027] 4. Significant economic benefits: The integrated structure saves 40% of the floor space, and combined with intelligent control, it reduces carbon source input by more than 30%, resulting in a 25-30% reduction in overall operating costs. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of an integrated coupled ozone oxidation denitrification device;

[0029] Figure 2 This is a schematic diagram of the second structure of this utility model;

[0030] The reference numerals in the accompanying drawings are as follows:

[0031] 1. Primary denitrification tank; 10. Inlet; 11. Mechanical agitator for primary denitrification tank; 12. Biological packing material for primary denitrification tank; 13. Return inlet for primary ozone oxidation tank; 14. Return inlet for secondary nitrification tank;

[0032] 2. Secondary denitrification tank; 21. Mechanical agitation in the secondary denitrification tank; 22. Biological packing material in the secondary denitrification tank;

[0033] 3. Primary ozone oxidation tank; 31. Titanium plate diffuser;

[0034] 4. Intermediate water tank; 41. Ozone dosing outlet; 41. Intermediate water tank return outlet; 43. Ozone dosing pump; 44. Intermediate water tank return pump; 45. Dissolved gas tank;

[0035] 5. Secondary ozone oxidation tank; 51. Ozone dosing equipment for the secondary ozone oxidation tank; 52. Ozone dosing port; 53. Return inlet of the primary nitrification tank;

[0036] 6. Deaeration tank; 61. Deaeration tank aeration equipment;

[0037] 7. Primary nitrification tank; 71. Aeration equipment for primary nitrification tank; 72. Biological packing material for primary nitrification tank; 73. Return effluent outlet for primary nitrification tank; 74. Return pump for primary nitrification tank.

[0038] 8. Secondary nitrification tank; 81. Aeration equipment for secondary nitrification tank; 82. Biological packing material for secondary nitrification tank; 83. Return effluent outlet for secondary nitrification tank; 84. Return pump for secondary nitrification tank;

[0039] 9. Outlet monitoring tank; 91. Inlet; Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0041] Reference Figure 1 A deep denitrification treatment device for recalcitrant wastewater coupled with ozone oxidation places the ozone oxidation tank between the denitrification tank and the nitrification tank. This allows for segmented influent, segmented oxidation, segmented nitrification, and segmented denitrification of recalcitrant wastewater, which helps ensure stable compliance of effluent COD, NH3-N, and TN levels. It also saves on ozone and carbon source dosages while reducing engineering investment and land occupation.

[0042] Example 1: A deep denitrification treatment device for recalcitrant wastewater coupled with ozone oxidation. Wastewater enters the primary denitrification tank 1 from the primary denitrification inlet 10. The primary denitrification tank is equipped with a mechanical stirring device 113 and filled with MBBR packing material with a filling rate of 40-50% and a retention time of 1-3 hours.

[0043] The primary denitrification tank 1 is connected to the secondary denitrification tank 2. The secondary denitrification tank 2 is equipped with a ceramic granule filter layer 22 with a thickness of 1.2-1.5m. A backwashing system 25 is installed below the filter layer with a retention time of 0.5-1h.

[0044] The secondary denitrification effluent enters the primary ozone oxidation tank 3. Ozone is added through the titanium plate diffuser 31 at the bottom of the primary ozone tank. The ozone contact oxidation method is adopted, and the residence time is 0.5 to 1 hour.

[0045] The primary ozone oxidation tank 3 is connected to the intermediate water tank 4. The intermediate water tank mixes wastewater with ozone and hydrogen peroxide through the outlet 41, the dosing pump 43 and the dissolved air tank 45, and then enters the secondary ozone oxidation tank 5 through the pressurized nozzle 51. The residence time is 0.2 to 0.5 hours.

[0046] The secondary ozone oxidation tank 5 is connected to the degassing tank 6. The degassing tank is equipped with aeration equipment 61 to remove residual ozone from the wastewater, with an air-to-water ratio of 3:1-5:1.

[0047] Wastewater enters the primary nitrification tank 7 after passing through the deaeration tank. The primary nitrification tank is filled with MBBR packing material 72 and equipped with disc aerators 71, with a filling rate of 45%-55% and a retention time of 0.5-1h.

[0048] The primary nitrification tank 7 is connected to the secondary nitrification tank 8. The secondary nitrification tank is equipped with a volcanic rock filter layer 82 with a thickness of 1.0-1.3m and a retention time of 1-3h.

[0049] The wastewater is finally treated in the effluent monitoring tank 9 and discharged after meeting the standards.

[0050] The intermediate water tank 23 is equipped with a return port 42, which is connected to the return port 13 of the first-stage denitrification tank through a pump and pipeline;

[0051] The primary nitrification tank 7 is equipped with a return port 73, which is connected to the return port 53 of the secondary ozone oxidation tank via a pump and pipeline;

[0052] The secondary nitrification tank 8 is equipped with a return port 83, which is connected to the return port 14 of the primary denitrification tank via a pump and pipeline.

[0053] Example 2

[0054] A type of coking wastewater with COD 300-500 mg / L, B / C 0.2, TN 80-100 mg / L, and ammonia nitrogen 50-80 mg / L.

[0055] The device using this invention comprises, in sequence, a primary denitrification tank, a secondary denitrification tank, a primary ozone oxidation tank, an intermediate water tank, a secondary ozone oxidation tank, a degassing tank, a primary nitrification tank, a secondary nitrification tank, and a monitoring tank. Specific parameters are as follows:

[0056] The ozone dosage in the primary and secondary ozone oxidation tanks is 50 mg / L and 30 mg / L, respectively, while the H2O2 dosage in the secondary ozone oxidation tank is 10 mg / L.

[0057] Intermediate water tank → Primary denitrification tank recirculation (recirculation ratio 200%)

[0058] Primary nitrification tank → Secondary ozone oxidation tank recirculation (recirculation ratio 100%)

[0059] Secondary nitrification tank → Primary denitrification tank recirculation (recirculation ratio 300%)

[0060] Denitrification supplement carbon source 200mg / L

[0061] Water ingress 485 0.2 84 56 Out of water 48 0.5 12 5

[0062] The process unit employs a three-stage reflux system to promote synergistic effects between ozone oxidation and biological denitrification: Reflux from the intermediate tank to the primary denitrification tank (reflux ratio 200%) reintroduces incompletely oxidized intermediate products (such as aldehydes) into the denitrification tank to replenish the carbon source; reflux from the primary nitrification tank to the secondary ozone oxidation tank (reflux ratio 100%) utilizes nitrite in the nitrification liquid to promote ozone catalytic oxidation (O3 / NO2). - (Path); Secondary nitrification tank → Primary denitrification tank recirculation (recirculation ratio 300%), ensuring deep nitrogen removal.

[0063] The primary ozone oxidation tank uses a titanium plate microporous diffuser (bubble diameter <100μm) to mainly degrade large molecular organic compounds (such as benzene compounds); the secondary ozone oxidation tank uses a jet dissolved air device (dissolved air efficiency >90%), and adds H2O2 to form O2. 3 / The H2O2 advanced oxidation system targets and decomposes small molecule organic compounds (such as carboxylic acids).

[0064] The primary denitrification tank is filled with MBBR packing (45% filling rate), and the secondary denitrification tank uses a ceramic granule filter layer (1.2m thick) to form a dual denitrification process of "biofilm-filtration". The primary nitrification tank is equipped with MBBR packing and disc aerators, and the secondary nitrification tank uses volcanic rock filter media (1.0m thick) to enhance ammonia nitrogen conversion and SS retention.

[0065] Each functional unit is separated by a vertical partition, and water flows through the bottom through-hole to avoid external pipes; Intelligent control system: Based on online monitoring of ORP and DO, the ozone dosage and reflux ratio are dynamically adjusted (e.g., when ORP>300mV, the ozone dosage is reduced by one level).

[0066] Comparative Example 1

[0067] Using the traditional ozone oxidation-AO combined process:

[0068] Ozone dosage 120 mg / L, traditional microporous aeration dosage;

[0069] Denitrification carbon source dosage: 260 mg / L

[0070]

[0071]

[0072] Based on the results of the comparative examples, the device of this invention uses ozone oxidation products (small molecule organic matter) as the carbon source for denitrification, increasing the total nitrogen removal rate from 60-70% in the traditional process to over 80%. The staged dosing and jet dissolved air technology enable ozone utilization to reach over 85%, reducing ozone consumption per ton of water from 2.6 kg / kg COD to 1.8 kg / kg COD, reducing carbon source dosage by over 30%, and lowering overall operating costs by 25-30%.

[0073] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A deep denitrification treatment device for recalcitrant wastewater coupled with ozone oxidation, characterized in that: The integrated pool structure is divided by partitions and includes, in order of water flow direction, a primary denitrification pool (1), a secondary denitrification pool (2), a primary ozone oxidation pool (3), an intermediate pool (4), a secondary ozone oxidation pool (5), a degassing pool (6), a primary nitrification pool (7), a secondary nitrification pool (8), and a monitoring pool (9). The primary denitrification tank (1) is equipped with an inlet (10), and the monitoring tank (9) is equipped with an outlet (91). The bottom of the intermediate water tank (4) is connected to the first-stage denitrification tank (1) via the first return pump (44), the bottom of the first-stage nitrification tank (7) is connected to the inlet of the second-stage ozone oxidation tank (5) via the second return pump (74), and the bottom of the second-stage nitrification tank (8) is connected to the first-stage denitrification tank (1) via the third return pump (84). The ozone dosage of the primary ozone oxidation tank (3) and the secondary ozone oxidation tank (5) is 30-50 mg / L and 15-30 mg / L, respectively, and the hydraulic retention time ratio is 2:

1.

2. The apparatus according to claim 1, characterized in that: The primary denitrification tank (1) is filled with MBBR packing material (12) with a filling rate of 40%-50%; the secondary denitrification tank (2) is equipped with a ceramic filter layer (22) with a thickness of 1.2-1.5m, and a backwashing system (25) is installed below the filter layer.

3. The apparatus according to claim 1, characterized in that: The primary ozone oxidation tank (3) adds ozone through a titanium plate diffuser (31) at the bottom of the tank; the secondary ozone oxidation tank (5) adds ozone through a jet injector (51).

4. The apparatus according to claim 1, characterized in that: The degassing tank (6) is equipped with perforated aeration pipes (61) with an air-to-water ratio of 3:1 to 5:

1.

5. The apparatus according to claim 1, characterized in that: The primary nitrification tank (7) is filled with MBBR packing material (12) and equipped with disc aerators (71), with a filling rate of 45%-55%; the secondary nitrification tank (8) is equipped with a volcanic rock filter layer (82) with a thickness of 1.0-1.3m.

6. The apparatus according to claim 1, characterized in that: A dissolved gas tank (45) is installed on the connecting pipe between the intermediate water tank (4) and the secondary ozone oxidation tank (5).

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