Low-energy-consumption sewage treatment process and treatment system

Abstract

The invention provides a low-energy-consumption sewage treatment process, and relates to the technical field of sewage treatment. The treatment process comprises the following steps: adjusting the content of dissolved oxygen (DO) in an aeration tank according to the TN / BOD data of inlet water, discharging the aerated sewage into a sedimentation tank for sedimentation, and refluxing the settled sludge into the first aeration tank to supplement the sludge concentration of the system; the nitrification liquid in the last aeration tank flows back to the first aeration tank for nitrogen removal by denitrification; the settled sewage overflows into a deep treatment tank for further treatment, and is discharged after reaching the standard after being treated. The proportion of the anoxic tank to the aerobic tank is flexibly adjusted according to the concentration proportion of total nitrogen of inlet water, so that matching of standard equipment and projects is realized. The invention also discloses a system for realizing the low-energy-consumption sewage treatment method.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a low-energy consumption sewage treatment process and a treatment system. Background Art

[0002] Sewage treatment equipment is generally designed with standardized equipment and fixed process parameters. However, when dealing with environmental conditions such as water quality concentration, influent C / N and temperature at different sites or when the operating water quality fluctuates greatly, it will be difficult for the effluent quality to meet the standards, especially COD, ammonia nitrogen and TN. When the water volume and low-concentration influent are low, excessive aeration or chemical addition will lead to high operating costs and reduced sludge performance, resulting in a series of system operation problems. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a low-energy sewage treatment process, which flexibly adjusts the ratio of anoxic tanks and aerobic tanks according to the concentration ratio of total nitrogen in the influent, thereby achieving matching of standard equipment and projects. The present invention also provides a system for implementing the above low-energy sewage treatment method.

[0004] The technical solution adopted by the present invention is:

[0005] A low-energy wastewater treatment process that adjusts the dissolved oxygen content in the aeration tank according to the influent ∆TN / ∆BOD data, and returns the nitrified liquid in the last aeration tank to the first aeration tank for denitrification; the wastewater after aeration is discharged into the sedimentation tank for sedimentation, and the precipitated sludge is returned to the first aeration tank to replenish the system sludge concentration; the precipitated wastewater overflows into the deep treatment tank for further treatment, and is discharged after the treatment meets the standards.

[0006] Optionally, when ∆TN / ∆BOD is in the range of 0.23-0.3 or 45mg / L≤TN≤60mg / L, the first aeration tank and the second aeration tank are set as anoxic tanks, and the aeration devices in the tanks are started and stopped intermittently; the third aeration tank and the fourth aeration tank are aerobic tanks, and the aeration devices in the tanks are always on;

[0007] When ∆TN / ∆BOD is ≤0.2 or TN ≤30mg / L, the first aeration tank is set as an anoxic tank, and the aeration device in the tank is started and stopped intermittently; the second, third and fourth aeration tanks are aerobic tanks, and the aeration devices in the tanks are always on;

[0008] When ∆TN / ∆BOD is between 0.2-0.23, the first aeration tank is an aerobic tank, the second aeration tank is adjusted to a micro-aerobic state, and the aeration device in the tank is started and stopped intermittently; the third and fourth aeration tanks are aerobic tanks, and the aeration devices in the tanks are always open;

[0009] When ∆TN / ∆BOD is higher than 0.3mg / L, first add the carbon source to reduce the ∆TN / ∆BOD in the water to below 0.3mg / L, then set the first aeration tank and the second aeration tank as anoxic tanks, and the aeration devices in the tanks are started and stopped intermittently; the third aeration tank and the fourth aeration tank are aerobic tanks, and the aeration devices in the tanks are always on;

[0010] When there is no need to remove total nitrogen from the site, the first aeration tank, the second aeration tank, the third aeration tank and the fourth aeration tank are all set as aerobic tanks, and the aeration devices in the tanks are always open.

[0011] Optionally, when ∆TN / ∆BOD is in the range of 0.23-0.3 or 45mg / L≤TN≤60mg / L, the aeration devices in the first aeration tank and the second aeration tank control the dissolved oxygen DO in the tanks at 0-0.5mg / L; the aeration devices in the third aeration tank and the fourth aeration tank control the dissolved oxygen DO in the tanks at 2-5mg / L.

[0012] Optionally, when ∆TN / ∆BOD is ≤0.2 or TN ≤30 mg / L, the aeration device in the first aeration tank controls the dissolved oxygen DO in the tank to be 0-0.5 mg / L; the aeration devices in the second aeration tank, the third aeration tank and the fourth aeration tank control the dissolved oxygen DO in the tank to be 2-5 mg / L.

[0013] Optionally, when ∆TN / ∆BOD is between 0.2-0.23, the aeration device in the first aeration tank controls the dissolved oxygen DO in the tank to be 0-0.5 mg / L, the aeration device in the second aeration tank controls the dissolved oxygen in the tank to be 0.5-1.0 mg / L, and the aeration device in the third aeration tank and the fourth aeration tank controls the dissolved oxygen DO in the tank to be 2-5 mg / L.

[0014] The above treatment process can flexibly adjust the ratio of the anoxic tank and the aerobic tank according to the concentration ratio of the total nitrogen during the treatment process, thereby achieving the matching of the standard equipment and the project. In order to better implement the above process, the present invention also provides a system for implementing the above low-energy consumption sewage treatment method, including:

[0015] Multiple aeration tanks, multiple aeration tanks are connected in sequence;

[0016] a sedimentation tank connected to the last aeration tank;

[0017] A deep treatment tank connected to the sedimentation tank;

[0018] an aeration device installed in each of the aeration tanks;

[0019] Two reflux devices, one of which is arranged in the last aeration tank, and the other is arranged in the sedimentation tank;

[0020] A dissolved oxygen meter, which is provided in the first two aeration tanks;

[0021] A controller is electrically connected to the aeration device, the reflux device and the dissolved oxygen meter.

[0022] Optionally, the aeration tanks include four, namely, a first aeration tank, a second aeration tank, a third aeration tank and a fourth aeration tank.

[0023] Optionally, the range of dissolved oxygen in the first aeration tank and the second aeration tank is adjusted according to ∆TN / ∆BOD of the influent.

[0024] Optionally, when the inlet TN exceeds 60 mg / L or the effluent requirement is below 15 mg / L, increase the number of aeration tanks.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. According to the concentration ratio of total nitrogen in the influent, the ratio of anoxic tank and aerobic tank can be flexibly adjusted to achieve the matching of standard equipment and projects.

[0027] 2. The same set of standard equipment can meet the different requirements of effluent water quality in different projects, so as to unify the design of the size and structure of each pool and realize the standardization and modular design and production of integrated equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of the overall plan structure of the low-energy sewage treatment system.

[0030] Figure 2 It is a schematic diagram of the plan view of the low-energy sewage treatment system.

[0031] Figure 3 This is a schematic diagram of the effluent quality of an agricultural pollution project in East China.

[0032] Reference numerals:

[0033] 1. Aeration tank;

[0034] 2. Sedimentation tank;

[0035] 3. Deep treatment pool;

[0036] 4. Aeration device;

[0037] 5. Reflux device;

[0038] 6. Dissolved oxygen meter;

[0039] 7. Controller. DETAILED DESCRIPTION

[0040] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0041] In the description of the present invention, it should be understood that the terms "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the products of the present invention are usually placed when in use, or are the orientations or positional relationships commonly understood by those skilled in the art. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0042] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0043] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0044] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0045] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0046] The embodiment of the present invention provides a low-energy consumption sewage treatment process, including: adjusting the dissolved oxygen DO content in the aeration tank according to the data of the influent ∆TN / ∆BOD (total nitrogen content / biochemical oxygen demand), and returning the nitrification liquid in the last aeration tank to the first aeration tank for denitrification treatment; the sewage after aeration is discharged into the sedimentation tank for sedimentation, and the precipitated sludge is returned to the first aeration tank to supplement the system sludge concentration (quantitatively returned according to the amount of sludge required in the first aeration tank); the precipitated sewage overflows into the deep treatment tank for further treatment, and is discharged after the treatment meets the standards.

[0047] like Figure 1 and Figure 2 As shown, the present invention also provides a system for realizing the above-mentioned low-energy sewage treatment method, including: four aeration tanks, a sedimentation tank, a deep treatment tank, an aeration device, two reflux devices, a dissolved oxygen meter and a controller. Multiple aeration tanks are connected in sequence. The sedimentation tank is connected to the last aeration tank. The deep treatment tank is connected to the sedimentation tank. An aeration device is installed in each aeration tank. One of the reflux devices is installed in the last aeration tank, and the other reflux device is installed in the sedimentation tank. The dissolved oxygen meter is installed in the first two aeration tanks. The controller is electrically connected to the aeration device, the reflux device and the dissolved oxygen meter.

[0048] The four aeration tanks are named the first aeration tank, the second aeration tank, the third aeration tank and the fourth aeration tank respectively.

[0049] During sewage treatment, when the influent ∆TN / ∆BOD is in the range of 0.23-0.3 or 45mg / L≤TN≤60mg / L, the first aeration tank and the second aeration tank are set as anoxic tanks, and the aeration device in the tank is started and stopped intermittently, and the dissolved oxygen DO is controlled between 0-0.5mg / L under the premise of ensuring that the sewage in the first aeration tank and the second aeration tank is stirred evenly. The third aeration tank and the fourth aeration tank are aerobic tanks to achieve aerobic function, so the aeration device in the tank is always open, so that the dissolved oxygen DO in the third aeration tank and the fourth aeration tank is between 2-5mg / L.

[0050] When ∆TN / ∆BOD is ≤0.2 or TN≤30mg / L, the first aeration tank is set as an anoxic tank, and the aeration device in the tank is started and stopped intermittently, so that the dissolved oxygen DO in the first aeration tank is between 0-0.5mg / L. The second, third and fourth aeration tanks are aerobic tanks, and the aeration devices in the tanks are always open, so that the dissolved oxygen DO in the second, third and fourth aeration tanks is between 2-5mg / L.

[0051] When ∆TN / ∆BOD is between 0.2-0.23, the first aeration tank is set as an anoxic tank, the aeration device in the tank is started and stopped intermittently, and the first aeration tank controls the dissolved oxygen DO between 0-0.5 mg / L. The second aeration tank is adjusted to a micro-aerobic state, the aeration device in the tank is started and stopped intermittently, and the aeration device in the second aeration tank controls the dissolved oxygen in the tank between 0.5-1.0 mg / L. The third and fourth aeration tanks are aerobic tanks, the aeration devices in the tanks are always open, and the aeration devices in the third and fourth aeration tanks control the dissolved oxygen DO in the tanks at 2-5 mg / L.

[0052] When ∆TN / ∆BOD is higher than 0.3mg / L, first add the carbon source to the water to reduce ∆TN / ∆BOD in the water to 0.23-0.3mg / L. Set the first aeration tank and the second aeration tank as anoxic tanks, and the aeration device in the tank is started and stopped intermittently to control the dissolved oxygen DO in the tank between 0-0.5mg / L. The third and fourth aeration tanks are aerobic tanks to achieve aerobic function, so the aeration device in the tank is always open, so that the dissolved oxygen DO in the third and fourth aeration tanks is between 2-5mg / L.

[0053] When the site has no need to remove total nitrogen, the first aeration tank, the second aeration tank, the third aeration tank and the fourth aeration tank are all set as aerobic tanks, the aeration devices in the tanks are always open, and the dissolved oxygen DO in the tanks is between 2-5 mg / L.

[0054] In one embodiment, when the inlet TN exceeds 60 mg / L or the outlet TN is required to be below 15 mg / L, the number of aeration tanks is increased.

[0055] During the treatment process, the above treatment process can flexibly adjust the ratio of anoxic tanks and aerobic tanks according to the concentration ratio of total nitrogen, thereby achieving matching of standard equipment and projects.

[0056] The specific system control process includes:

[0057] A detector for detecting the ∆TN / ∆BOD content in the sewage is provided at the sewage inlet at the front end of the first aeration tank, and the detected data is fed back to the controller. The controller controls the aeration device to adjust the aeration frequency so that the dissolved oxygen DO content in the first aeration tank and the second aeration tank is within the preset range (in order to avoid the dissolved oxygen DO content in the first aeration tank and the second aeration tank not being within the preset range, a dissolved oxygen meter is provided in the first aeration tank and the second aeration tank to detect the oxygen content of the sewage during the treatment process, and to feed back the information to the controller, so as to facilitate the controller to adjust the working frequency of the aeration device.). The controller controls the aeration device in the third aeration tank and the fourth aeration tank to be always open, and aeration treatment is performed on the sewage in the third aeration tank and the fourth aeration tank. The sewage treated by aeration enters the sedimentation tank by overflow for sedimentation, and the sewage after sedimentation enters the deep treatment tank for deep treatment, and the sewage that meets the treatment standard is discharged. The nitrified liquid in the fourth aeration tank flows back to the first aeration tank through the reflux device for denitrification and denitrification treatment. The sludge in the sedimentation tank is quantitatively returned to the first aeration tank through the return device to replenish the sludge content in the first aeration tank.

[0058] In a 2000 cubic meters / day pump station overflow sewage treatment project, the influent ∆TN / ∆BOD was maintained between 0.05-0.35, the system switched to Vo / Va=3:1 or 1:1, and the effluent quality reached the national standard Grade A for a long time. During the rainy season, the influent TN was less than 10mg / L, and the TN met the direct discharge requirements. The system was adjusted to full aerobic mode, the nitrification liquid reflux was stopped, and all indicators met the discharge requirements, and the operating energy consumption was reduced by about 10%.

[0059] In a decentralized agricultural sewage project in East China, a low-energy sewage treatment system was designed for 200 sites. When the ∆TN / ∆BOD change was less than 0.2, it was switched to Vo / Va=3:1, and when it was higher than 0.23, it was switched back to Vo / Va=1:1. During the entire operation process, when the inlet water quality fluctuation was ≤30%, the effluent TN compliance rate reached more than 88%. The operating energy consumption was reduced by more than 20% compared with the traditional process (such as Figure 3 as shown).

[0060] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low-energy sewage treatment process, characterized in that: The dissolved oxygen content in the aeration tank is adjusted according to the influent ∆TN / ∆BOD data, and the nitrified liquid in the last aeration tank is returned to the first aeration tank for denitrification and denitrification; the sewage after aeration is discharged into the sedimentation tank for sedimentation, and the precipitated sludge is returned to the first aeration tank to replenish the system sludge concentration; the precipitated sewage overflows into the deep treatment tank for further treatment and is discharged after the treatment meets the standards.

2. The low-energy wastewater treatment process according to claim 1, characterized in that: When ∆TN / ∆BOD is in the range of 0.23-0.3 or 45mg / L≤TN≤60mg / L, the first and second aeration tanks are set as anoxic tanks, and the aeration devices in the tanks are started and stopped intermittently; the third and fourth aeration tanks are aerobic tanks, and the aeration devices in the tanks are always on; When ∆TN / ∆BOD is ≤0.2 or TN ≤30mg / L, the first aeration tank is set as an anoxic tank, and the aeration device in the tank is started and stopped intermittently; the second, third and fourth aeration tanks are aerobic tanks, and the aeration devices in the tanks are always on; When ∆TN / ∆BOD is between 0.2-0.23, the first aeration tank is an aerobic tank, the second aeration tank is adjusted to a micro-aerobic state, and the aeration device in the tank is started and stopped intermittently; the third and fourth aeration tanks are aerobic tanks, and the aeration devices in the tanks are always open; When ∆TN / ∆BOD is higher than 0.3mg / L, first add the carbon source to reduce the ∆TN / ∆BOD in the water to below 0.3mg / L, then set the first aeration tank and the second aeration tank as anoxic tanks, and the aeration devices in the tanks are started and stopped intermittently; the third aeration tank and the fourth aeration tank are aerobic tanks, and the aeration devices in the tanks are always on; When there is no need to remove total nitrogen from the site, the first aeration tank, the second aeration tank, the third aeration tank and the fourth aeration tank are all set as aerobic tanks, and the aeration devices in the tanks are always open.

3. The low-energy wastewater treatment process according to claim 2, characterized in that: When ∆TN / ∆BOD is in the range of 0.23-0.3 or 45mg / L≤TN≤60mg / L, the aeration devices in the first aeration tank and the second aeration tank control the dissolved oxygen DO in the tank at 0-0.5mg / L; the aeration devices in the third aeration tank and the fourth aeration tank control the dissolved oxygen DO in the tank at 2-5mg / L.

4. The low-energy wastewater treatment process according to claim 2, characterized in that: When ∆TN / ∆BOD is ≤0.2 or TN ≤30mg / L, the aeration device in the first aeration tank controls the dissolved oxygen DO in the tank to be 0-0.5mg / L; the aeration devices in the second aeration tank, the third aeration tank and the fourth aeration tank control the dissolved oxygen DO in the tank to be 2-5mg / L.

5. The low-energy wastewater treatment process according to claim 2, characterized in that: When ∆TN / ∆BOD is between 0.2-0.23, the aeration device in the first aeration tank controls the dissolved oxygen DO in the tank at 0-0.5 mg / L, the aeration device in the second aeration tank controls the dissolved oxygen in the tank at 0.5-1.0 mg / L, and the aeration devices in the third and fourth aeration tanks control the dissolved oxygen DO in the tank at 2-5 mg / L.

6. A system for implementing the low-energy wastewater treatment method according to any one of claims 1 to 5, characterized in that: include: Multiple aeration tanks, multiple aeration tanks are connected in sequence; a sedimentation tank connected to the last aeration tank; A deep treatment tank connected to the sedimentation tank; an aeration device installed in each of the aeration tanks; Two reflux devices, one of which is arranged in the last aeration tank, and the other is arranged in the sedimentation tank; A dissolved oxygen meter, which is provided in the first two aeration tanks; A controller is electrically connected to the aeration device, the reflux device and the dissolved oxygen meter.

7. The low-energy sewage treatment system according to claim 6, characterized in that: The aeration tanks include four, namely the first aeration tank, the second aeration tank, the third aeration tank and the fourth aeration tank.

8. The low-energy sewage treatment system according to claim 7, characterized in that: Adjust the range of dissolved oxygen in the first aeration tank and the second aeration tank according to the ∆TN / ∆BOD of the influent.

9. The low-energy sewage treatment system according to claim 7, characterized in that: When the inlet TN exceeds 60 mg / L or the effluent requirement is below 15 mg / L, increase the number of aeration tanks.

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