A low-carbon-source sewage advanced denitrification treatment system device and system method

Abstract

This invention provides a system and method for deep denitrification treatment of low-carbon-source wastewater. The system includes a main stream denitrification unit and a side stream hydrolysis unit. The main stream denitrification unit includes an anoxic reaction device, an aerobic reaction device, a membrane bioreactor, and a reflux device connected in sequence. The side stream hydrolysis unit includes a first cyclone device, a second cyclone device, and a hydrolysis device. The system reduces the dissolved oxygen carried by the reflux mixed liquor, reduces the competition of dissolved oxygen for denitrification carbon sources, and increases the total nitrogen removal rate.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment and relates to a wastewater denitrification system and method, particularly a deep denitrification system and method for low-carbon source wastewater. Background Technology

[0002] With the continuous improvement of urban living standards, the concentration of organic matter in urban domestic sewage is decreasing while the concentration of ammonia nitrogen is increasing, resulting in a continuous decline in the C / N ratio. To achieve TN (total nitrogen) compliance for low C / N sewage discharge, current engineering practices often employ the addition of commercial carbon sources. However, the addition of commercial carbon sources undoubtedly increases sewage treatment operating costs.

[0003] In fact, the sludge produced daily from wastewater treatment is itself a relatively stable and reliable usable carbon source. Sludge hydrolysis technology based on utilizing the "internal carbon source" of wastewater treatment has been gradually researched and applied in engineering abroad. CN102241462A proposes a bypass sludge reduction, sediment separation, and nitrogen and phosphorus removal wastewater treatment system and method to address common problems encountered in current nitrogen and phosphorus removal processes, such as high influent sand content, low VSS / MLSS, and insufficient carbon source. However, it lacks necessary pretreatment of the influent to the sludge reduction tank, and the dissolved oxygen content and effective component content of the activated sludge are not effectively controlled, resulting in low hydrolysis efficiency and low internal carbon source yield in the sludge reduction tank. CN113461284A discloses a municipal sludge treatment method using nitrate-enhanced hot hydrolysis, which improves the decomposition efficiency of sludge flocs and other recalcitrant organic matter by adding nitrate agents to the sludge for hot hydrolysis. However, it suffers from drawbacks such as high energy and chemical consumption, high equipment requirements, and poor applicability in practical engineering. Summary of the Invention

[0004] To address the technical problems existing in the prior art, the present invention provides a low-carbon-source wastewater deep denitrification system device and method, wherein the system device enhances the utilization of the mainstream internal carbon source and the release of the side stream internal carbon source.

[0005] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0006] One objective of this invention is to provide a deep denitrification system for low-carbon wastewater, the system comprising a main stream denitrification unit and a side stream hydrolysis unit;

[0007] The main denitrification unit includes an anoxic reaction device, an aerobic reaction device, a membrane bioreactor, and a reflux device connected in sequence.

[0008] The side-flow hydrolysis unit includes a first cyclone device, a second cyclone device, and a hydrolysis device;

[0009] The first vortex device includes an inlet, an overflow outlet, and a bottom liquid outlet;

[0010] The second vortex device includes an inlet, an overflow outlet, and a bottom liquid outlet;

[0011] The inlet of the first cyclone device is connected to the outlet of the reflux device;

[0012] The overflow outlet of the first cyclone device is connected to the inlet of the second cyclone device;

[0013] The overflow outlet of the second vortex device is connected to the outlet of the reflux device;

[0014] The bottom liquid outlet of the second cyclone device is connected to the liquid inlet of the hydrolysis device;

[0015] The outlet of the hydrolysis device is connected to the anoxic reaction device.

[0016] The outlet of the reflux device is independently connected to the anoxic reaction device and the first vortex device.

[0017] As a preferred embodiment of the present invention, the anoxic reaction device includes an anoxic pool.

[0018] In this invention, the bottom liquid outlet of the first cyclone device is connected to the sludge dewatering system for further processing of the sludge separated by the first cyclone device.

[0019] Preferably, the anoxic reaction device is equipped with a packing assembly, a stirring assembly, and a dissolved oxygen monitoring assembly.

[0020] Preferably, the packing assembly includes suspended packing.

[0021] In this invention, the suspended packing material creates an anaerobic / anoxic microenvironment, which facilitates the attachment and growth of denitrifying bacteria, promotes their enrichment, and also promotes the attachment and growth of hydrolytic and fermentative bacteria, enhancing the utilization of the main internal carbon source and improving the denitrification effect. Preferably, the filling rate of the suspended packing material in the anoxic tank is 60%–80%.

[0022] Preferably, the mixing assembly includes a submersible mixer.

[0023] In this invention, the mixing power of the submersible mixer is 1W / m³. 3 ~3W / m 3 This ensures uniform mixing in the main space of the anoxic tank while creating a partial "anaerobic dead zone" space to promote the release of internal carbon sources and enhance the denitrification effect.

[0024] Preferably, the dissolved oxygen monitoring component is located at the outlet of the hypoxia reaction device.

[0025] As a preferred embodiment of the present invention, the aerobic reaction device includes an aerobic tank.

[0026] Preferably, the aerobic reaction device is equipped with a packing assembly, an aeration assembly, and a dissolved oxygen monitoring assembly.

[0027] Preferably, the packing assembly includes suspended packing.

[0028] In this invention, an "anaerobic / aerobic" microenvironment is formed on the suspended packing material, which facilitates simultaneous nitrification and denitrification, reducing energy consumption and the demand for nitrogen removal carbon sources. Preferably, the suspended packing material is a bio-rope packing material composed of a central rope and bio-attached fiber rings to enhance the packing material's ability to cut air bubbles and transfer oxygen. Preferably, the filling rate of the suspended packing material in the aerobic tank is 60%–80%.

[0029] Preferably, the dissolved oxygen monitoring component is located at the liquid outlet of the aerobic reaction device.

[0030] As a preferred embodiment of the present invention, the membrane bioreactor includes an MBR membrane tank.

[0031] Preferably, the MBR membrane tank is equipped with an MBR module and a sludge concentration monitoring module.

[0032] Preferably, the sludge concentration monitoring component is located at the outlet of the membrane bioreactor.

[0033] As a preferred embodiment of the present invention, an oxygen removal component is provided at the inlet of the reflux device.

[0034] Preferably, the oxygen desiccation component includes an oxygen desiccation baffle.

[0035] As a preferred embodiment of the present invention, the reflux device includes a reflux pool.

[0036] Preferably, the reflux device includes a reflux pump and a dissolved oxygen monitoring component.

[0037] Preferably, the reflux pump is located at the outlet of the reflux device.

[0038] Preferably, the dissolved oxygen monitoring component is located at the outlet of the reflux device.

[0039] As a preferred embodiment of the present invention, the first swirling device includes a first swirler.

[0040] Preferably, the device diameter D of the first hydrocyclone is ≤150mm, and the cone angle α of the first hydrocyclone is 10°≤α≤20°.

[0041] In this invention, the main functions of the first cyclone device include: (1) ash separation, which enhances the separation of activated sludge and inorganic inert components in the reflux mixture, thereby improving the hydrolysis efficiency of the subsequent hydrolysis tank and reducing the difficulty of sludge dewatering and separation; (2) cyclone carbon release, which generates shearing, squeezing, centrifugal and collision forces to increase the concentration of available internal carbon sources.

[0042] In this invention, the first vortex device further includes the following structural parameters: inlet diameter D1, 0.15D≤D1≤0.3D; overflow diameter D2, 0.2D≤D2≤0.4D; underflow diameter D3, 0.1D≤D3≤0.2D; underflow diameter to overflow diameter ratio D3 / D2, 0.4≤D3 / D2≤0.6; cylindrical section length L, D≤L≤2D.

[0043] In this invention, the specific operating parameters of the first hydrocyclone device are as follows: inlet pressure P1, 0.2MPa≤P1≤0.4MPa; inlet sludge concentration M1, 6000mg / L≤M1≤15000mg / L.

[0044] As a preferred embodiment of the present invention, the second swirling device includes a second swirler.

[0045] Preferably, the device diameter d of the second hydrocyclone is ≤200mm, and the cone angle β of the second hydrocyclone is 20°≤β≤30°.

[0046] In this invention, the main functions of the second cyclone device include: (1) further cyclone carbon release, generating shearing, squeezing, centrifugal and collision forces to increase the concentration of available internal carbon sources; (2) sludge thickening, increasing the concentration of activated sludge, improving the hydrolysis efficiency of the subsequent hydrolysis tank, and reducing the hydraulic residence time of the hydrolysis tank; (3) cyclone degassing, with the pressure distribution inside the cyclone device being large at the sidewalls and decreasing radially until it drops to a negative pressure, which is conducive to removing dissolved oxygen and creating a favorable environment for hydrolysis in the hydrolysis tank.

[0047] In this invention, the second vortex device further includes the following structural parameters: inlet diameter d1, 0.12d≤d1≤0.25d; overflow diameter d2, 0.1d≤d2≤0.2d; underflow diameter d3, 0.15d≤d2≤0.3d; underflow diameter to overflow diameter ratio d3 / d2, 1.5≤d3 / d2≤2; cylindrical section length l, d≤l≤2d.

[0048] Preferably, the specific operating parameters of the second hydrocyclone device are as follows: inlet pressure P2, 0.2MPa≤P2≤0.4MPa; inlet sludge concentration M2, 10000mg / L≤M2≤50000mg / L.

[0049] In this invention, the flow rate ratio of the bottom liquid outlet to the overflow liquid outlet in the second cyclone device is 10:1 to 20:1.

[0050] The core function of the first hydrocyclone is ash separation, where the density and particle size differences between activated sludge and inorganic inert components in the mixed liquor are relatively small. Hydrocyclones with relatively small device diameters, a ratio of underflow to overflow diameters, and cone angles are selected to facilitate the enrichment of activated sludge at the overflow port and inorganic inert components at the underflow port.

[0051] The core function of the second hydrocyclone is sludge thickening. Hydrocyclones with relatively large device diameters, ratios of underflow diameter to overflow diameter, and cone angles are selected to facilitate the enrichment of activated sludge at the underflow port of the second hydrocyclone.

[0052] In this invention, the hydrolysis device includes a hydrolysis tank. The main function of the hydrolysis device is to break down the sludge at the underflow outlet of the second hydrocyclone in the hydrolysis tank, providing an internal carbon source for the system.

[0053] The second objective of this invention is to provide a method for deep denitrification treatment of low-carbon source wastewater, wherein the method uses the aforementioned system apparatus and includes the following steps:

[0054] (1) Wastewater enters the anoxic reactor to undergo denitrification to obtain the first treated wastewater;

[0055] (2) The first treated wastewater enters the aerobic reaction device to carry out organic matter degradation reaction and nitrification reaction to obtain the second treated wastewater. The dissolved oxygen monitoring component monitors the dissolved oxygen concentration of the second treated wastewater.

[0056] (3) The second treated wastewater enters the membrane bioreactor for solid-liquid separation, and the permeate passes through the deoxygenation component and enters the reflux device;

[0057] (4) Part of the reflux liquid generated by the reflux device is directly returned to the anoxic reaction device, and the remaining part of the reflux liquid is processed by the first cyclone device, the second cyclone device and the hydrolysis device in sequence before being returned to the anoxic reaction device.

[0058] As a preferred technical solution of the present invention, the dissolved oxygen concentration of the anoxic reaction device in step (1) is 0.2 mg / L to 0.4 mg / L.

[0059] Preferably, the dissolved oxygen concentration of the aerobic reaction device in step (2) is 0.7 mg / L to 1.2 mg / L.

[0060] Preferably, the sludge concentration of the membrane bioreactor in step (3) is 6000 mg / L to 15000 mg / L.

[0061] Preferably, the dissolved oxygen concentration of the reflux liquid in step (4) is 0.2 mg / L to 0.4 mg / L.

[0062] Preferably, in step (4), the flow rate of the reflux liquid sent from the outlet of the reflux device to the anoxic reaction device is 200%Q to 400%Q, where Q is the inlet water flow rate; and the flow rate of the reflux liquid sent from the outlet of the reflux device to the first vortex device is 1%Q to 20%Q.

[0063] Compared with the prior art, the present invention has at least the following beneficial effects:

[0064] (1) The present invention provides a deep denitrification treatment system for low carbon source wastewater. The main denitrification unit of the system constructs an anaerobic / anoxic reaction device and an aerobic / aerobic reaction device microenvironment by adding suspended packing and controlling dissolved oxygen, thereby enhancing the utilization of carbon source in the main body and saving the amount of external carbon source added.

[0065] (2) The present invention provides a low-carbon source wastewater deep denitrification treatment system. The side-flow hydrolysis unit of the system uses two-stage cyclone degassing and sludge thickening to reduce the dissolved oxygen concentration in the hydrolysis tank to 0.1 mg / L and increase the sludge concentration in the hydrolysis tank to a maximum of 50,000 mg / L, thereby promoting sludge hydrolysis and shortening the hydraulic retention time in the hydrolysis tank to 24 h to 72 h, which is 50% lower than the traditional anaerobic hydrolysis process.

[0066] (3) The present invention provides a low carbon source wastewater deep denitrification treatment system device. The COD of the supernatant of the mixed liquor returned from the side flow hydrolysis unit of the system device to the anoxic reaction device can be as high as 200 mg / L, which supplements the carbon source for the denitrification reaction and saves the amount of external carbon source added. Attached Figure Description

[0067] Figure 1 A schematic diagram of the structure of a low-carbon source wastewater deep denitrification treatment system device provided for a specific embodiment of the present invention.

[0068] Figure 2 A schematic diagram of the structure of the first swirl device provided for a specific embodiment of the present invention.

[0069] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0070] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0071] Example 1

[0072] This embodiment provides a deep denitrification system for low-carbon source wastewater, the system comprising a main stream denitrification unit and a side stream hydrolysis unit;

[0073] The main denitrification unit includes an anoxic reaction device, an aerobic reaction device, a membrane bioreactor, and a reflux device connected in sequence.

[0074] The side-flow hydrolysis unit includes a first cyclone device, a second cyclone device, and a hydrolysis device;

[0075] The first vortex device includes an inlet, an overflow outlet, and a bottom liquid outlet;

[0076] The second vortex device includes an inlet, an overflow outlet, and a bottom liquid outlet;

[0077] The inlet of the first cyclone device is connected to the outlet of the reflux device;

[0078] The overflow outlet of the first cyclone device is connected to the inlet of the second cyclone device;

[0079] The overflow outlet of the second vortex device is connected to the outlet of the reflux device;

[0080] The bottom liquid outlet of the second cyclone device is connected to the liquid inlet of the hydrolysis device;

[0081] The outlet of the hydrolysis device is connected to the anoxic reaction device.

[0082] The outlet of the reflux device is independently connected to the anoxic reaction device and the first vortex device.

[0083] Example 2

[0084] This embodiment provides a low-carbon-source wastewater deep denitrification treatment system device, the structure of which is as follows: Figure 1 As shown, the system includes a main stream denitrification unit and a side stream hydrolysis unit;

[0085] The main denitrification unit includes an anoxic reaction device, an aerobic reaction device, a membrane bioreactor, and a reflux device connected in sequence.

[0086] The anoxic reaction device includes an anoxic tank and is equipped with a suspended packing material and a submersible agitator.

[0087] The aerobic reaction device includes an aerobic tank, a dissolved oxygen monitoring component is installed at the outlet of the aerobic reaction device, and a suspended packing material is installed in the aerobic reaction device;

[0088] The membrane bioreactor includes an MBR membrane tank, which is equipped with an MBR module and a sludge concentration monitoring module. The sludge concentration monitoring module is located at the outlet of the membrane bioreactor.

[0089] An oxygen-removing baffle is provided at the inlet of the reflux device. The reflux device includes a reflux tank, and is also equipped with a reflux pump and a dissolved oxygen monitoring component. The reflux pump and the dissolved oxygen monitoring component are located at the outlet of the reflux device.

[0090] The side-flow hydrolysis unit includes a first cyclone device, a second cyclone device, and a hydrolysis device;

[0091] The first vortex device includes an inlet, an overflow outlet, and a bottom liquid outlet;

[0092] The second vortex device includes an inlet, an overflow outlet, and a bottom liquid outlet;

[0093] The inlet of the first cyclone device is connected to the outlet of the reflux device;

[0094] The overflow outlet of the first cyclone device is connected to the inlet of the second cyclone device;

[0095] The overflow outlet of the second vortex device is connected to the outlet of the reflux device;

[0096] The bottom liquid outlet of the second cyclone device is connected to the liquid inlet of the hydrolysis device;

[0097] The first swirling device is a first swirler, and its structure is as follows: Figure 2 As shown, the device diameter D of the first hydrocyclone is 100 mm, the inlet diameter D1 is 25 mm, the overflow diameter D2 is 25 mm, the underflow diameter D3 is 15 mm, and the cone angle α of the first hydrocyclone is 10°≤α≤20°.

[0098] The second swirling device is a second hydrocyclone. The device diameter d of the second hydrocyclone is 150 mm, the inlet diameter d1 is 30 mm, the overflow diameter d2 is 22.5 mm, the underflow diameter d3 is 37.5 mm, and the cone angle β of the second hydrocyclone is 20°≤β≤30°.

[0099] The outlet of the hydrolysis device is connected to the anoxic reaction device, and the hydrolysis device is a hydrolysis tank;

[0100] The outlet of the reflux device is independently connected to the anoxic reaction device and the first vortex device.

[0101] The first vortex device also includes the following structural parameters: inlet diameter D1, 0.15D≤D1≤0.3D; overflow diameter D2, 0.2D≤D2≤0.4D; underflow diameter D3, 0.1D≤D3≤0.2D; underflow diameter to overflow diameter ratio D3 / D2, 0.4≤D3 / D2≤0.6; cylindrical section length L, D≤L≤2D.

[0102] The second vortex device also includes the following structural parameters: inlet diameter d1, 0.12d≤d1≤0.25d; overflow diameter d2, 0.1d≤d3≤0.2d; underflow diameter d3, 0.15d≤d2≤0.3d; underflow diameter to overflow diameter ratio d3 / d2, 1.5≤d3 / d2≤2; cylindrical section length l, d≤l≤2d.

[0103] Application Example 1

[0104] This application example provides a method for deep denitrification treatment of low-carbon source wastewater. The method uses the system apparatus provided in Example 2 and includes the following steps:

[0105] (1) Wastewater enters the anoxic tank for denitrification. The submersible mixer in the anoxic tank has a mixing power of 1W / m³. 3 The wastewater was treated to obtain the first stage of treatment.

[0106] (2) The first treated wastewater enters the aerobic tank for degradation and nitrification to obtain the second treated wastewater. The dissolved oxygen monitoring component monitors the dissolved oxygen concentration of the second treated wastewater, and the dissolved oxygen concentration is controlled to be 0.7 mg / L to 1.2 mg / L.

[0107] (3) The second treated wastewater enters the membrane bioreactor and undergoes solid-liquid separation through the MBR module. The liquid enters the return tank through the deoxygenation baffle. The dissolved oxygen concentration at the end of the return tank is controlled to be 0.2 mg / L to 0.4 mg / L.

[0108] (4) The reflux liquid generated by the reflux device is processed sequentially by the first cyclone device, the second cyclone device and the hydrolysis device and then returned to the anoxic reaction device.

[0109] In step (4), the reflux ratio of the reflux device is 200%, and the reflux liquid flow rate from the outlet of the reflux pump to the first cyclone device is 10%Q. The ratio of the bottom liquid outlet to the overflow liquid flow rate in the first cyclone device is 1:20, the ratio of the bottom liquid outlet to the overflow liquid flow rate in the second cyclone device is 10:1, the hydraulic residence time of the hydrolysis device is 24h, and the oxidation-reduction potential of the hydrolysis device is controlled at -300 to -200mV.

[0110] Application Example 2

[0111] This application example provides a method for deep denitrification treatment of low-carbon source wastewater. The method uses the system apparatus provided in Example 2 and includes the following steps:

[0112] (1) Wastewater enters the anoxic tank for denitrification. The submersible mixer in the anoxic tank has a mixing power of 3W / m³. 3 The wastewater was treated to obtain the first stage of treatment.

[0113] (2) The first treated wastewater enters the aerobic tank for degradation and nitrification to obtain the second treated wastewater. The dissolved oxygen monitoring component monitors the dissolved oxygen concentration of the second treated wastewater, and the dissolved oxygen concentration is controlled to be 0.7 mg / L to 1.2 mg / L.

[0114] (3) The second treated wastewater enters the membrane bioreactor and undergoes solid-liquid separation through the MBR module. The liquid enters the return tank through the deoxygenation baffle. The dissolved oxygen concentration at the end of the return tank is controlled to be 0.2 mg / L to 0.4 mg / L.

[0115] (4) The reflux liquid generated by the reflux device is processed sequentially by the first cyclone device, the second cyclone device and the hydrolysis device and then returned to the anoxic reaction device.

[0116] In step (4), the reflux ratio of the reflux device is 400%, and the reflux liquid flow rate from the outlet of the reflux pump to the first cyclone device is 10%Q. The ratio of the bottom liquid outlet to the overflow liquid flow rate in the first cyclone device is 1:10, the ratio of the bottom liquid outlet to the overflow liquid flow rate in the second cyclone device is 20:1, the hydraulic residence time of the hydrolysis device is 72h, and the oxidation-reduction potential of the hydrolysis device is controlled to be -300 to -200mV.

[0117] Application Example 3

[0118] This application example provides a method for deep denitrification treatment of low-carbon source wastewater. The method uses the system apparatus provided in Example 2 and includes the following steps:

[0119] (1) Wastewater enters the anoxic tank for denitrification. The submersible mixer in the anoxic tank has a mixing power of 2W / m³. 3 The wastewater was treated to obtain the first stage of treatment.

[0120] (2) The first treated wastewater enters the aerobic tank for degradation and nitrification to obtain the second treated wastewater. The dissolved oxygen monitoring component monitors the dissolved oxygen concentration of the second treated wastewater, and the dissolved oxygen concentration is controlled to be 0.7 mg / L to 1.2 mg / L.

[0121] (3) The second treated wastewater enters the membrane bioreactor and undergoes solid-liquid separation through the MBR module. The liquid enters the return tank through the deoxygenation baffle. The dissolved oxygen concentration at the end of the return tank is controlled to be 0.2 mg / L to 0.4 mg / L.

[0122] (4) The reflux liquid generated by the reflux device is processed sequentially by the first cyclone device, the second cyclone device and the hydrolysis device and then returned to the anoxic reaction device.

[0123] In step (4), the reflux ratio of the reflux device is 300%, and the reflux liquid flow rate from the outlet of the reflux pump to the first cyclone device is 15%Q. The ratio of the bottom liquid outlet to the overflow liquid flow rate in the first cyclone device is 1:15, and the ratio of the bottom liquid outlet to the overflow liquid flow rate in the second cyclone device is 15:1. The hydraulic residence time of the hydrolysis device is 48h, and the oxidation-reduction potential of the hydrolysis device is controlled to be -300 to -200mV.

[0124] Comparative Application Example 1

[0125] In this comparative application example, the dissolved oxygen concentration of the second treated wastewater is not monitored or controlled, and all other conditions are the same as in application example 3.

[0126] Comparative Application Example 2

[0127] In this comparative application example, except for the absence of an oxygen desiccation baffle, all other conditions are the same as in application example 3.

[0128] Comparative Application Example 3

[0129] In this comparative application example, the overflow liquid in the second cyclone device does not flow back, but all other conditions are the same as in application example 3.

[0130] Comparative Application Example 4

[0131] In this comparative application example, the low-carbon source wastewater deep denitrification treatment system used does not have a second hydrocyclone installed, and all other conditions are the same as in application example 3.

[0132] Comparative Application Example 5

[0133] In this comparative application example, the device structure dimensions of the second hydrocyclone are the same as those of the first hydrocyclone, and all other conditions are the same as in application example 3.

[0134] The suspended packing in Examples 1-3 uses a bio-rope packing consisting of a central rope and bio-attached fiber rings, with a filling rate of 70%.

[0135] Application Examples 1-3 and Comparative Application Examples 1-5 treated low C / N domestic sewage with a flow rate of 1000 m³. 3 / d, the influent CODcr concentration is 100mg / L, NH3-N concentration is 30mg / L, TN concentration is 35mg / L, and the added carbon source is sodium acetate.

[0136] The total nitrogen removal and carbon source consumption were tested for corresponding use cases 1-3 and comparative application examples 1-5, and the results are shown in Table 1.

[0137] Table 1

[0138] Total nitrogen removal / mg / L Additional carbon source consumption / kg / d Application Example 1 25.1 300 Application Example 2 28.3 300 Application Example 3 24.7 300 Comparative Application Example 1 24.3 500 Comparative Application Example 2 24.7 525 Comparative Application Example 3 23.1 400 Comparative Application Example 4 23.3 700 Comparative Application Example 5 22.4 800

[0139] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0140] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0141] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0142] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A deep denitrification system for low-carbon source wastewater, characterized in that, The system includes a main stream denitrification unit and a side stream hydrolysis unit; The main denitrification unit includes an anoxic reaction device, an aerobic reaction device, a membrane bioreactor, and a reflux device connected in sequence. The side-flow hydrolysis unit includes a first cyclone device, a second cyclone device, and a hydrolysis device; The first vortex device includes an inlet, an overflow outlet, and a bottom liquid outlet; The second vortex device includes an inlet, an overflow outlet, and a bottom liquid outlet; The inlet of the first cyclone device is connected to the outlet of the reflux device; The overflow outlet of the first cyclone device is connected to the inlet of the second cyclone device; The overflow outlet of the second vortex device is connected to the outlet of the reflux device; The bottom liquid outlet of the second cyclone device is connected to the liquid inlet of the hydrolysis device; The outlet of the hydrolysis device is connected to the anoxic reaction device. The outlet of the reflux device is independently connected to the anoxic reaction device and the first vortex device, respectively; An oxygen elimination component is provided at the liquid inlet of the reflux device, and the oxygen elimination component includes an oxygen elimination baffle.

2. The system apparatus according to claim 1, characterized in that, The anoxic reaction device includes an anoxic pool.

3. The system apparatus according to claim 1, characterized in that, The oxygen-deficient reaction device is equipped with a packing assembly and a stirring assembly.

4. The system apparatus according to claim 3, characterized in that, The packing assembly includes suspended packing.

5. The system apparatus according to claim 3, characterized in that, The mixing assembly includes a submersible mixer.

6. The system apparatus according to claim 1, characterized in that, The aerobic reaction device includes an aerobic tank.

7. The system apparatus according to claim 1, characterized in that, The aerobic reaction device is equipped with a dissolved oxygen monitoring component.

8. The system apparatus according to claim 1, characterized in that, The aerobic reaction device is equipped with a packing assembly.

9. The system apparatus according to claim 8, characterized in that, The packing assembly includes suspended packing.

10. The system apparatus according to claim 7, characterized in that, The dissolved oxygen monitoring component is located at the outlet of the aerobic reaction device.

11. The system apparatus according to claim 1, characterized in that, The membrane bioreactor includes an MBR membrane tank.

12. The system apparatus according to claim 11, characterized in that, The MBR membrane tank is equipped with MBR components and sludge concentration monitoring components.

13. The system apparatus according to claim 12, characterized in that, The sludge concentration monitoring component is installed at the outlet of the membrane bioreactor.

14. The system apparatus according to claim 1, characterized in that, The reflux device includes a reflux pool.

15. The system apparatus according to claim 1, characterized in that, The reflux device is equipped with a reflux pump and a dissolved oxygen monitoring component.

16. The system apparatus according to claim 15, characterized in that, The reflux pump is located at the outlet of the reflux device.

17. The system apparatus according to claim 15, characterized in that, The dissolved oxygen monitoring component is located at the outlet of the reflux device.

18. The system apparatus according to claim 1, characterized in that, The first swirling device includes a first swirler.

19. The system apparatus according to claim 18, characterized in that, The device diameter D of the first hydrocyclone is ≤150mm, and the cone angle α of the first hydrocyclone is 10°≤α≤20°.

20. The system apparatus according to claim 1, characterized in that, The second swirling device includes a second swirler.

21. The system apparatus according to claim 20, characterized in that, The device diameter d of the second hydrocyclone is ≤200mm, and the cone angle β of the second hydrocyclone is 20°≤β≤30°.

22. A method for deep denitrification treatment system of low-carbon source wastewater, characterized in that, The system method uses the system apparatus according to any one of claims 1-21, and the system method includes the following steps: (1) Wastewater enters the anoxic reactor to undergo denitrification, resulting in the first treated wastewater; (2) The first treated wastewater enters the aerobic reaction device to carry out organic matter degradation reaction and nitrification reaction to obtain the second treated wastewater. The dissolved oxygen monitoring component monitors the dissolved oxygen concentration of the second treated wastewater. (3) The second treated wastewater enters the membrane bioreactor for solid-liquid separation, and the permeate passes through the deoxygenation component and enters the reflux device; (4) Part of the reflux liquid generated by the reflux device is directly returned to the anoxic reaction device, and the remaining part of the reflux liquid is processed by the first cyclone device, the second cyclone device and the hydrolysis device in sequence before being returned to the anoxic reaction device.

23. The system method according to claim 22, characterized in that, The dissolved oxygen concentration in the oxygen-deficient reaction device in step (1) is 0.2 mg / L to 0.4 mg / L.

24. The system method according to claim 22, characterized in that, The dissolved oxygen concentration in the aerobic reaction device in step (2) is 0.7 mg / L to 1.2 mg / L.

25. The system method according to claim 22, characterized in that, The sludge concentration of the membrane bioreactor in step (3) is 6000 mg / L to 15000 mg / L.

26. The system method according to claim 22, characterized in that, The dissolved oxygen concentration of the reflux liquid in step (4) is 0.2 mg / L to 0.4 mg / L.

27. The system method according to claim 22, characterized in that, In step (4), the flow rate of the reflux liquid sent from the outlet of the reflux device to the anoxic reaction device is 200%Q~400%Q, where Q is the inlet water flow rate; the flow rate of the reflux liquid sent from the outlet of the reflux pump to the first vortex device is 1%Q~20%Q.

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