Device and process for strengthening denitrification effect of AO (anoxic-oxic) process

Abstract

The invention relates to the technical field of coking wastewater treatment, in particular to a device and process for strengthening the denitrification effect of AO (anaerobic-anoxic) processes, the device is arranged above an anaerobic tank or an anoxic tank and comprises a culture device, the culture device is of a box structure, the ratio of the bottom edge length to the bottom edge height is 1: 4-1: 6, an activated sludge inlet is formed in the upper portion of the culture device, and a sludge outlet is formed in the lower portion of the culture device. An activated sludge outlet is formed in the lower part of the box body, a nutrient solution monitoring port is formed in the middle of the box body, a plurality of aeration heads are arranged at the bottom in the culture device and are connected with an air pump through aeration pipelines, a pH value monitoring port is formed in the culture device, an overflow weir is arranged at the top of the culture device, and a grid is arranged on the overflow weir at a water outlet in the box body. The device has the beneficial effects of simple preparation process, simplicity and convenience in operation, lower cost and easiness in industrial application.

Description

Technical Field

[0001] This invention relates to the field of coking wastewater treatment technology, and in particular to an apparatus and process for enhancing the denitrification effect of AO process. Background Technology

[0002] Coking wastewater contains large amounts of organic matter and pollutants, and is recognized as difficult to treat. Biological methods are the most economical technical route for total nitrogen removal. The AO (anaerobic digestion) process is currently the mainstream biological wastewater treatment process, and many other processes are developed from AO treatment. Currently, the A / O, A / A / O, O / A / O, and A / O / A / O processes commonly used in the coking industry are based on the traditional "nitrification-denitrification" nitrogen removal theory. The binding requirement of a total nitrogen emission of less than 20 mg / L, particularly the nitrogen content in the wastewater from the A / O process, severely restricts the normal production and operation of the coking industry chain.

[0003] The AO process itself has a certain capacity to treat coking wastewater and its operating costs are relatively low. However, with increasingly stringent environmental protection requirements, the AO treatment process can no longer meet stricter emission standards, and the economic burden of demolition and reconstruction is difficult for many enterprises to bear. There is an urgent need for a process that can improve the treatment capacity of AO without demolition and reconstruction, thereby saving construction costs and meeting environmental protection requirements.

[0004] Chinese invention patent CN117342678A, entitled "Accumulation Method of High-Efficiency Denitrification Sludge System," discloses a method for obtaining a high-efficiency denitrification sludge system by accumulating and enriching ordinary activated sludge with nitrifying bacteria in an aerobic tank. Under continuous and stable aeration conditions, this system simultaneously undergoes short-cut nitrification and denitrification reactions. This patented high-efficiency denitrification sludge system can convert thiocyanate in coking wastewater into ammonia nitrogen, utilizing the ammonia nitrogen for simultaneous short-cut nitrification and denitrification, achieving a COD removal rate of over 85%. Compared to the traditional AO process, it offers more efficient and rapid denitrification, and is simpler to operate, significantly reducing operating costs. However, this patent requires the dismantling of the existing AO facilities and the construction of new ones for its application; therefore, it cannot be directly applied to the AO process.

[0005] Patent publication number CN118929910B, "A Method for Cultivating Activated Sludge for Treating Coking Wastewater," discloses a method for preparing a microbial immobilization carrier using bio-enhanced strains and rice husk biochar. This carrier is then added to a simulated coking wastewater activated sludge treatment system to form bio-enhanced activated sludge. This activated sludge is subsequently added to simulated coking wastewater with gradually increasing concentrations of phenol, nitrogen-containing heterocyclic compounds, and polycyclic aromatic hydrocarbons for three stages of acclimation, resulting in activated sludge after the third acclimation. This acclimated activated sludge is then applied to treat simulated coking wastewater. The activated sludge of this invention, after the third acclimation, can simultaneously and efficiently degrade multiple target pollutants in simulated coking wastewater. However, this patent requires three acclimation stages, making the process complex and costly, and it is not applicable to AO (Active Acid) processes. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention provides a device and process for enhancing the denitrification effect of AO processes. A cultivation device is set above an anaerobic or anoxic tank. Activated sludge is placed in the cultivation device for enhanced cultivation and then introduced into the anaerobic or anoxic tank to enhance denitrification. The device has a simple preparation process, is easy to operate, has low cost, and is easy to apply industrially. It does not require the dismantling of the AO process and can be modified on the AO process, greatly saving costs.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A device for enhancing the denitrification effect of AO process is provided. The device is placed above an anaerobic or anoxic tank and includes a cultivation device. The cultivation device is a box structure with a bottom side length to height ratio of 1:4 to 1:6. An activated sludge inlet is provided at the top of the cultivation device, an activated sludge outlet is provided at the bottom, and a nutrient solution monitoring port is provided in the middle. Several aeration heads are provided at the bottom of the cultivation device and are connected to an air pump through aeration pipes. A pH monitoring port is provided on the cultivation device, and an overflow weir is provided at the top of the cultivation device. A grid is provided at the outlet of the overflow weir inside the box.

[0008] Furthermore, the overflow weir discharges excess liquid from the culture device into an anaerobic or anoxic tank.

[0009] An enhanced denitrification process for an apparatus to improve the denitrification effect of AO-type processes includes the following steps: S1. Activated sludge and coking wastewater from the aerobic tank are pumped into the culture device through the activated sludge inlet. The amount of activated sludge added is controlled at 6000-12000 mg / L. S2. The pH monitoring port is equipped with a pH monitoring device and a conduit to introduce the mixed solution to control the pH value in the culture device, maintaining the pH value between 6.5 and 7.5. Every 3 to 15 hours, nutrient solution is pumped in through the nutrient solution monitoring port, with the volume of the pumped nutrient solution being 0.02% to 0.05% of the volume of the culture device. S3. First, nitrogen gas is introduced into the aeration pipeline to make the DO of the liquid in the culture device < 0.2 mg / L, and this is maintained for 12 to 24 hours, while controlling the pH value at 7 to 7.5. Then, oxygen gas is introduced into the aeration pipeline to make the DO of the liquid in the culture device 2 to 4 mg / L, and this is maintained for 12 to 24 hours, while controlling the pH value at 7.5 to 8. Nitrogen gas is then introduced into the aeration pipeline again to make the DO of the liquid in the culture device < 0.2 mg / L, and this is maintained for 24 to 48 hours, while controlling the pH value at 7 to 7.5. S4. Every 2 to 4 days, the enhanced activated sludge in the cultivation device is pumped into the anaerobic or anoxic tank through the activated sludge outlet to enhance denitrification.

[0010] Furthermore, the mixed solution comprises sodium carbonate, sodium acetate, sodium hydrogen phosphate, and sodium dihydrogen phosphate, mixed in a mass ratio of 1–2:1.5–3.5:1–3:1–3.

[0011] Furthermore, the nutrient solution composition is as follows: glucose: 0.5-2 g / L, FeSO4: 0.2-0.6 g / L, sodium citrate: 0.2-0.8 g / L.

[0012] Furthermore, the nitrogen content in the anoxic or anaerobic tank after enhanced denitrification is less than 10 mg / L; the denitrification rate is above 85%.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1) The device has a simple preparation process, is easy to operate, and has a low cost, making it easy to apply industrially; it does not require dismantling the AO process and can be modified on the AO process, which greatly saves costs.

[0014] 2) The nitrogen content in the anoxic or anaerobic tank after enhanced denitrification is less than 10 mg / L; the denitrification rate is above 85%. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the device structure for enhancing the denitrification effect of AO-type processes according to the present invention.

[0016] In the diagram: 1. Activated sludge inlet; 2. pH monitoring port; 3. Aeration pipeline; 4. Activated sludge outlet; 5. Nutrient solution monitoring port; 6. Cultivation device; 7. Overflow weir; 8. Grid. Detailed Implementation

[0017] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings: like Figure 1 As shown, a device for enhancing the denitrification effect of AO process is placed above an anaerobic or anoxic tank. The device includes a cultivation unit 6, which is a rectangular box structure with a bottom side length to height ratio of 1:4 to 1:6. The upper part of the cultivation unit 6 has an activated sludge inlet 1, the lower part has an activated sludge outlet 4, and a nutrient solution monitoring port 2 is located in the middle. Several aeration heads are installed at the bottom of the cultivation unit 6, connected to an aeration pipe 3. A pH monitoring port 2 is installed on the cultivation unit 6, and an overflow weir 7 is installed at the top of the cultivation unit 6. The overflow weir 7 discharges excess liquid from the cultivation unit 6 into the anaerobic or anoxic tank. A grid 8 is installed at the outlet of the overflow weir 7 inside the box. The grid 8 prevents unenhanced activated sludge from entering the anaerobic or anoxic tank during the discharge of excess liquid from the box.

[0018] An enhancement process for an apparatus to improve the denitrification effect of AO-type processes includes the following steps: S1. Activated sludge and coking wastewater from the aerobic tank are pumped into the culture device 6 through the activated sludge inlet 1. The amount of activated sludge added is controlled at 6000-12000 mg / L. S2, pH monitoring port 2 is equipped with a pH monitoring device and conduit. A mixed solution is prepared by mixing sodium carbonate, sodium acetate, sodium hydrogen phosphate, and sodium dihydrogen phosphate in a mass ratio of 1-2:1.5-3.5:1-3:1-3 to control the pH value in the culture device 6, maintaining the pH value between 6.5 and 7.5. Nutrient solution is pumped in through nutrient solution monitoring port 5 every 3-15 hours. The volume of nutrient solution pumped in is 0.02-0.05% of the volume of culture device 6. The nutrient solution composition is: glucose: 0.5-2 g / L, FeSO4: 0.2-0.6 g / L, sodium citrate: 0.2-0.8 g / L.

[0019] S3. Nitrogen gas is first introduced into aeration pipe 3 to make the DO of the liquid in culture device 6 < 0.2 mg / L, and this is maintained for 12 to 24 hours, while controlling the pH value at 7 to 7.5. Then, oxygen gas is introduced into aeration pipe 3 to make the DO of the liquid in culture device 6 2 to 4 mg / L, and this is maintained for 12 to 24 hours, while controlling the pH value at 7.5 to 8. Nitrogen gas is then introduced into aeration pipe 3 again to make the DO of the liquid in culture device 6 < 0.2 mg / L, and this is maintained for 24 to 48 hours, while controlling the pH value at 7 to 7.5. S4. Every 2 to 4 days, the enhanced activated sludge in the cultivation device 6 is pumped into the anaerobic or anoxic tank through the activated sludge outlet 4 to enhance denitrification.

[0020] like Figure 1As shown in Table 1, the enhanced process parameters and effect parameters of the embodiments of the present invention are shown in Table 1; the comparative example uses the traditional AO treatment process to treat coking wastewater.

[0021] Table 1 - Enhanced process parameters and effect parameters of the present invention in the embodiments: As can be seen from the above embodiments, the activated sludge cultured in the device of the present invention achieves a nitrogen removal rate of over 85% in wastewater treatment.

[0022] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A device for enhancing the denitrification effect of AO-type processes, characterized in that, The device is placed above an anaerobic or anoxic tank and includes a cultivation device. The cultivation device is a box structure with a bottom side length to height ratio of 1:4 to 1:

6. The upper part of the cultivation device is equipped with an activated sludge inlet, the lower part with an activated sludge outlet, and the middle with a nutrient solution monitoring port. Several aeration heads are installed at the bottom of the cultivation device, and these aeration heads are connected to an air pump through aeration pipes. A pH monitoring port is installed on the cultivation device, and an overflow weir is installed at the top of the cultivation device. A grid is installed inside the box at the outlet of the overflow weir.

2. The device for enhancing the denitrification effect of AO-type processes according to claim 1, characterized in that, The overflow weir discharges excess liquid from the culture device into the anaerobic or anoxic tank.

3. An enhanced denitrification process based on the apparatus for enhancing the denitrification effect of AO-type processes as described in claim 1, characterized in that, The specific method includes the following steps: S1. Activated sludge and coking wastewater from the aerobic tank are pumped into the culture device through the activated sludge inlet. The amount of activated sludge added is controlled at 6000-12000 mg / L. S2. The pH monitoring port is equipped with a pH monitoring device and a conduit to introduce the mixed solution to control the pH value in the culture device, maintaining the pH value between 6.5 and 7.

5. Every 3 to 15 hours, nutrient solution is pumped in through the nutrient solution monitoring port, with the volume of the pumped nutrient solution being 0.02% to 0.05% of the volume of the culture device. S3. First, nitrogen gas is introduced into the aeration pipeline to make the DO of the liquid in the culture device < 0.2 mg / L, and this is maintained for 12 to 24 hours, while controlling the pH value at 7 to 7.

5. Then, oxygen gas is introduced into the aeration pipeline to make the DO of the liquid in the culture device 2 to 4 mg / L, and this is maintained for 12 to 24 hours, while controlling the pH value at 7.5 to 8. Nitrogen gas is then introduced into the aeration pipeline again to make the DO of the liquid in the culture device < 0.2 mg / L, and this is maintained for 24 to 48 hours, while controlling the pH value at 7 to 7.

5. S4. Every 2 to 4 days, the enhanced activated sludge in the cultivation device is pumped into the anaerobic or anoxic tank through the activated sludge outlet to enhance denitrification.

4. The enhanced denitrification process of the device for enhancing the denitrification effect of AO-type processes according to claim 3, characterized in that, The mixed solution comprises sodium carbonate, sodium acetate, sodium hydrogen phosphate, and sodium dihydrogen phosphate, mixed in a mass ratio of 1-2:1.5-3.5:1-3:1-3.

5. The enhanced denitrification process of the device for enhancing the denitrification effect of AO-type processes according to claim 3, characterized in that, The nutrient solution consists of: glucose: 0.5-2 g / L, FeSO4: 0.2-0.6 g / L, and sodium citrate: 0.2-0.8 g / L.

6. The enhanced denitrification process of the device for enhancing the denitrification effect of AO-type processes according to claim 3, characterized in that, The nitrogen content in the anoxic or anaerobic tank after enhanced denitrification is less than 10 mg / L; the denitrification rate is above 85%.

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