Device and method for treating urban low-carbon-nitrogen-ratio sewage through SLOAO process

Abstract

The invention belongs to the technical field of biological sewage treatment, and discloses a device and method for treating urban low-carbon-nitrogen-ratio sewage through an SLOAO process, a sewage inlet is formed in the bottom of the water inlet side of a first low-oxygen aerobic tank and connected with a water inlet pipe through a pipeline, and a first water outlet is formed in the water outlet side of the first low-oxygen aerobic tank and connected with a water outlet pipe through a pipeline; the first water outlet is communicated with the anoxic tank, the water outlet side of the anoxic tank is also provided with a second water outlet, the second water outlet is communicated with the second aerobic tank, the water outlet side of the second aerobic tank is connected with the sedimentation tank, the bottom of the anoxic tank is also provided with an anoxic tank sewage inlet, and the anoxic tank sewage inlet is also connected with the water inlet pipe through a pipeline; stirring devices are arranged in the first low-oxygen aerobic tank and the anoxic tank, aeration pipes are arranged at the bottoms of the first low-oxygen aerobic tank and the second aerobic tank, the aeration pipes are externally connected with an air blower, and the stirring devices and the air blower are electrically connected with the control assembly.

Description

Technical Field

[0001] The present application belongs to the technical field of biological treatment of sewage, and specifically relates to a device and method for treating urban low carbon-nitrogen ratio sewage by SLOAO process. Background Art

[0002] With the rapid development of my country's economy and the acceleration of urbanization, the discharge of domestic and industrial sewage has increased year by year, and the problems of water shortage and pollution have become increasingly serious. my country has also had more stringent requirements for the control of pollutants such as nitrogen and phosphorus. Therefore, efficient treatment of sewage has become an environmental problem that the industry needs to overcome urgently. Due to urban development and changes in residents' domestic water habits and problems with municipal pipe networks, the influent of sewage treatment plants generally presents the characteristics of low C / N. Theoretical studies have shown that in practical applications, a C / N value of more than 4.00 is generally required to meet the requirements of microbial denitrification and denitrification. When sewage treatment plants treat low C / N sewage, it is difficult to ensure the efficient removal of total nitrogen, but the removal of TP (total phosphorus) can be completed by deep treatment and dosing.

[0003] At present, sewage treatment plants widely use activated sludge method to treat sewage, relying on microorganisms to remove pollutants such as organic matter, nitrogen and phosphorus. However, when treating low C / N sewage, the traditional nitrification / denitrification process, such as AAO process (a commonly used secondary sewage treatment process), has problems such as high aeration energy consumption, low carbon source utilization rate of raw sewage, large amount of external carbon source, high energy consumption of reflux pump, etc., resulting in high sewage treatment costs. On the premise of ensuring efficient denitrification, how to reduce energy consumption and drug consumption in the sewage treatment process and achieve carbon reduction and efficiency improvement in sewage treatment is a research hotspot in the sewage treatment industry.

[0004] In summary, the existing technologies have the following problems: (1) Traditional biological treatment processes do not fully utilize the carbon source in the raw sewage and cannot meet the carbon source requirements of different bacterial communities; (2) Sewage treatment plants need to add additional carbon sources when treating low C / N sewage, which increases reagent consumption; (3) The pre-denitrification setting makes the denitrification efficiency dependent on the size of the internal recirculation ratio, which increases the energy consumption of the recirculation pump and increases the cost of sewage treatment.

[0005] Based on this, developing a new wastewater treatment process with high efficiency in nitrogen removal is an important aspect of the current research on low C / N wastewater treatment technology. Summary of the invention

[0006] The purpose of this application is to solve the problems of the prior art and to provide a device and method for treating urban low carbon-nitrogen ratio sewage using a SLOAO process.

[0007] In order to solve the technical problem, the technical solution of the present application is: a device for treating urban low carbon nitrogen ratio sewage by SLOAO process, comprising a first low oxygen aerobic tank, an anoxic tank, a second aerobic tank and a sedimentation tank connected in sequence, and a control component, wherein a sewage inlet is arranged at the bottom of the water inlet side of the first low oxygen aerobic tank, and the sewage inlet is connected to the water inlet pipe through a pipeline, a first water outlet is arranged on the water outlet side of the first low oxygen aerobic tank, and the first water outlet is connected to the anoxic tank, and a second water outlet is also arranged on the water outlet side of the anoxic tank, and the second water outlet The first aerobic tank is connected to the second aerobic tank, the outlet side of the second aerobic tank is connected to the sedimentation tank, the planes where the first outlet and the second outlet are located are higher than the plane where the sewage inlet is located, the bottom of the anoxic tank is also provided with an anoxic tank sewage inlet, the anoxic tank sewage inlet is also connected to the water inlet pipe through a pipeline, the first low oxygen aerobic tank and the anoxic tank are both provided with a stirring device, the bottoms of the first low oxygen aerobic tank and the second aerobic tank are both provided with an aeration pipe, the aeration pipe is externally connected to a blower, and the stirring device and the blower are respectively electrically connected to the control component; The dissolved oxygen concentration of the first hypoxic aerobic tank is 0.5-0.9 mg / L, and the dissolved oxygen concentration of the second aerobic tank is 1.5-2 mg / L. The first hypoxic aerobic tank is inoculated with activated sludge. The activated sludge makes the cumulative rate of nitrite nitrogen in part of the sewage entering from the sewage inlet reach 50% or more, realizing short-term nitrification and acclimation. The sewage after the short-term nitrification reaction is mixed with another part of the sewage entering the anoxic tank from the sewage inlet of the anoxic tank to undergo a short-term denitrification reaction and a phosphorus release process by polyphosphate bacteria. The sewage after the reaction is transported to the second aerobic tank for phosphorus absorption and removal of organic matter, and then transported to the sedimentation tank to obtain the treated water body.

[0008] Preferably, the sewage inlet and the anoxic tank sewage inlet are both connected to the water inlet pipe via an inlet pump, and the inlet pump is electrically connected to the control component.

[0009] Preferably, the bottom of the sedimentation tank is connected to the sludge return port at the bottom of the first low oxygen aerobic tank through a pipeline, and a sludge return pump is provided on the pipeline, and the sludge return pump is electrically connected to the control component.

[0010] Preferably, a method for treating urban low carbon nitrogen ratio sewage by SLOAO process, using a device for treating urban low carbon nitrogen ratio sewage by SLOAO process as described in any of the above items to treat sewage, specifically comprises the following steps: Step 1: Sludge inoculation and acclimatization: Inoculate the activated sludge into the first hypoxic aerobic tank, acclimate the activated sludge, control the dissolved oxygen concentration of the first hypoxic aerobic tank to 0.5-0.9 mg / L, and make the cumulative rate of nitrite nitrogen reach 50% or more, so as to achieve short-range nitrification acclimatization; Step 2: Calculate the water inlet split ratio r according to the water inlet parameters of the water inlet pipe, and transport the sewage to the first low oxygen aerobic pool and the anoxic pool through the water inlet pipe according to the water inlet split ratio r; Step 3: A portion of the sewage passes through the first hypoxic aerobic tank for short-range nitrification reaction and then enters the anoxic tank; Step 4: The sewage after the short-cut nitrification reaction is mixed with another part of the sewage transported to the anoxic tank through the water inlet pipe to carry out the short-cut denitrification reaction and the phosphorus release process of polyphosphate bacteria; Step 5: The wastewater after the reaction in step 4 is transported to the second aerobic tank, and the dissolved oxygen concentration in the second aerobic tank is controlled to be 1.5-2 mg / L to carry out the phosphorus absorption process and organic matter removal, and then transported to the sedimentation tank to obtain the treated water.

[0011] Preferably, step 1 is specifically as follows: taking activated sludge from a conventional process and inoculating it into a first hypoxic aerobic tank, ventilating the activated sludge for 1 day to activate the activity of the activated sludge, controlling the dissolved oxygen concentration of the first hypoxic aerobic tank to be 0.5-0.9 mg / L, and the hydraulic retention time to be 2-4 h, and continuously monitoring the nitrite nitrogen concentration in the effluent of the first hypoxic aerobic tank. When the cumulative rate of nitrite nitrogen reaches 50% or more, it is considered that the short-term nitrification acclimation is completed.

[0012] Preferably, the calculation method of the water inlet split ratio r in step 2 is: the water inlet split ratio r refers to the proportion of sewage entering the first hypoxic aerobic tank to the total water inlet of the water inlet pipe, and the calculation formula of the water inlet split ratio r is:

[0013] Where: —— ;

[0014] ——NH3-N concentration in influent, mg / L; —— ; ——

[0015] ——Removal rate of organic matter in the first hypoxic aerobic pool; The calculation formula for the organic matter removal rate of the first hypoxic aerobic pool is:

[0016] Where: —— ,℃; —— ; —— ; ——

[0017] —— ; —— , d -1 ; ——Hydraulic retention time of the first hypoxic aerobic tank, h; ——sludge concentration, mg / L; ——MLVSS / MLSS; ——Influent COD concentration, mg / L.

[0018] Preferably, step 3 is specifically as follows: after the inlet water split ratio r is calculated, the sewage is transported to the first hypoxic aerobic tank through the water inlet pipe to undergo a short-range nitrification reaction to generate nitrite nitrogen. The first hypoxic aerobic tank is provided with a stirring device. The dissolved oxygen concentration in the sewage is controlled at 0.5-0.9 mg / L by a rotor flowmeter, the hydraulic retention time is controlled at 2-4 h, the sludge concentration is maintained at 3000-5000 mg / L, some organic matter is removed, and the sewage after the reaction enters the anoxic tank.

[0019] Preferably, step 4 is specifically as follows: the effluent from the first hypoxic aerobic tank is transported to the bottom of the anoxic tank, and an anoxic tank sewage inlet is provided at the bottom of the anoxic tank. According to the calculation of the inlet diversion ratio r, another part of the sewage is directly transported to the anoxic tank through the inlet pipe. A stirring device is provided in the anoxic tank, and the hydraulic retention time is controlled at 3 to 5 hours. The sludge concentration is maintained at 3000 to 5000 mg / L. The microorganisms in the anoxic tank use the residual organic matter from the reaction of the first hypoxic aerobic tank and the organic matter entering the sewage from the sewage inlet of the anoxic tank as electron donors. The nitrite nitrogen generated by the reaction in the first hypoxic aerobic tank is used as an electron acceptor for a short-range denitrification reaction, and the phosphorus release process of polyphosphate bacteria is carried out at the same time. The sewage after the reaction in the anoxic tank enters the second aerobic tank.

[0020] Preferably, step 5 is specifically as follows: the effluent from the anoxic tank is transported to the bottom of the second aerobic tank, an aeration pipe is provided at the bottom of the second aerobic tank, the dissolved oxygen concentration in the water is controlled at 1.5-2 mg / L by a rotor flowmeter, the hydraulic retention time is controlled at 2-4 h, the sludge concentration is maintained at 3000-5000 mg / L, the microorganisms in the second aerobic tank deeply remove organic matter and nitrogen and complete the phosphorus absorption process of polyphosphate bacteria, and the sewage after the reaction enters the sedimentation tank.

[0021] Preferably, the sedimentation tank is provided with a sludge return system, the sludge return ratio is controlled at 70% to 100%, and the sludge is returned to the bottom of the first hypoxic aerobic tank through the sludge return port.

[0022] Compared with the prior art, the advantages of this application are: (1) The present application provides a device and method for treating urban low carbon nitrogen ratio sewage by SLOAO process, which has high denitrification efficiency, low aeration energy consumption, no internal reflow and zero / low addition of carbon source, significantly improving the denitrification efficiency of low carbon nitrogen wastewater, reducing energy consumption in sewage treatment process, reducing overall sewage treatment cost, and improving treatment efficiency and economic benefits; (2) The method of the present application allows a portion of the sewage to undergo a short-cut nitrification reaction in the first low-oxygen aerobic tank, and the nitrite nitrogen generated by the reaction directly enters the anoxic tank to undergo a short-cut denitrification reaction with another portion of the sewage, thereby eliminating the step of reflux of the nitrification liquid in the traditional process, abandoning the setting of the traditional denitrification pre-denitrification, and reducing the energy consumption of the internal reflux pump; (3) This application proposes to divert the sewage inflow, and determines the calculation method of the inflow diversion ratio based on the inflow water quality, so as to make full use of the carbon source in the raw sewage, meet the carbon source requirements of different spatial bacterial communities, and achieve low / zero carbon source addition; (4) The first hypoxic aerobic pool of the present application realizes short-range nitrification under low dissolved oxygen conditions, reduces the aeration volume and the carbon source demand in the denitrification process, and realizes efficient nitrogen removal; (5) In the present application, the sludge is returned to the first low-oxygen aerobic tank, which activates the sludge activity and enhances the reproduction of the dominant bacteria of short-range nitrification and denitrification. The application of short-range nitrification and denitrification in the SLOAO process of the present application reduces the reaction time of the sewage in the biological pool, that is, reduces its hydraulic retention time, and reduces the size of the structure and the floor space compared to the conventional AAO process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of a device for treating urban low carbon-nitrogen ratio sewage using a SLOAO process according to the present application; Figure 2 The effluent NO of the first hypoxic aerobic pool of Example 1 of the present application is x - -N change graph; Figure 3 This is a comparative change diagram of the concentration of each pollutant in the effluent of Example 1 of the present application; Figure 4 The effluent NO of the first hypoxic aerobic pool of Example 2 of the present application is x - -N change graph; Figure 5 This is a comparative change diagram of the concentrations of various pollutants in the effluent of Example 2 of the present application.

[0024] Description of reference numerals: 1. The first low oxygen aerobic tank, 2. The anoxic tank, 3. The second aerobic tank, 4. The stirring device, 5. The first water outlet, 6. The water inlet pump, 7. The sewage inlet, 8. The aeration pipe, 9. The blower, 10. The sludge return port, 11. The anoxic tank sewage inlet, 12. The sludge return pump, 13. The sedimentation tank, 14. The second water outlet, 15. The water inlet pipe. DETAILED DESCRIPTION

[0025] The present application is described in detail below in conjunction with the accompanying drawings and specific embodiments, but the present application is not limited to these embodiments. The present application covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present application. In order to make the public have a thorough understanding of the present application, specific details are described in detail in the following embodiments of the present application, and those skilled in the art can fully understand the present application without the description of these details.

[0026] like Figure 1 As shown, the present application discloses a device for treating urban low carbon nitrogen ratio sewage by SLOAO process, SplitLow-oxygen Oxic-Anoxia-Oxic: Split low oxygen aerobic-anoxic-aerobic process is referred to as SLOAO process, comprising a first low oxygen aerobic pool 1, an anoxic pool 2, a second aerobic pool 3 and a sedimentation pool 13 connected in sequence, and a control component, wherein a sewage inlet 7 is provided at the bottom of the water inlet side of the first low oxygen aerobic pool 1, and the sewage inlet 7 is connected to the water inlet pipe 15 through a pipeline, a first water outlet 5 is provided at the water outlet side of the first low oxygen aerobic pool 1, and the first water outlet 5 is connected to the anoxic pool 2, and a second water outlet 14 is also provided at the water outlet side of the anoxic pool 2, and the second water outlet 14 is connected to the second The aerobic pool 3 is connected, the outlet side of the second aerobic pool 3 is connected to the sedimentation tank 13, the plane where the first water outlet 5 and the second water outlet 14 are located is higher than the plane where the sewage inlet 7 is located, and the bottom of the anoxic pool 2 is also provided with an anoxic pool sewage inlet 11, and the anoxic pool sewage inlet 11 is also connected to the water inlet pipe 15 through a pipeline, and the first low oxygen aerobic pool 1 and the anoxic pool 2 are both provided with a stirring device 4, and the bottom of the first low oxygen aerobic pool 1 and the second aerobic pool 3 are both provided with an aeration pipe 8, and the aeration pipe 8 is externally connected to a blower 9, and the stirring device 4 and the blower 9 are respectively electrically connected to the control component; The dissolved oxygen concentration of the first hypoxic aerobic tank 1 is 0.5-0.9 mg / L, and the dissolved oxygen concentration of the second aerobic tank 3 is 1.5-2 mg / L. The first hypoxic aerobic tank 1 is inoculated with activated sludge. The activated sludge makes the cumulative rate of nitrite nitrogen in part of the sewage entering from the sewage inlet 7 reach 50% or more, realizing short-term nitrification and acclimation. The sewage after the short-term nitrification reaction is mixed with another part of the sewage entering the anoxic tank 2 from the anoxic tank sewage inlet 11 to undergo a short-term denitrification reaction and a phosphorus release process by polyphosphate bacteria. The sewage after the reaction is transported to the second aerobic tank 3 to undergo a phosphorus absorption process and organic matter removal, and then transported to the sedimentation tank 13 to obtain the treated water body.

[0027] Preferably, the sewage inlet 7 and the anoxic tank sewage inlet 11 are both connected to the water inlet pipe 15 via the water inlet pump 6, and the water inlet pump 6 is electrically connected to the control component.

[0028] Preferably, the bottom of the sedimentation tank 13 is connected to the sludge return port 10 at the bottom of the first hypoxic aerobic tank 1 through a pipeline, and a sludge return pump 12 is provided on the pipeline, and the sludge return pump 12 is electrically connected to the control component.

[0029] Preferably, a method for treating urban low carbon nitrogen ratio sewage by SLOAO process, using a device for treating urban low carbon nitrogen ratio sewage by SLOAO process described in any one of the above items to treat sewage, specifically comprises the following steps: Step 1: sludge inoculation and acclimation; inoculate the activated sludge into the first hypoxic aerobic tank 1, acclimate the activated sludge, control the dissolved oxygen concentration of the first hypoxic aerobic tank 1 to be 0.5-0.9 mg / L, and make the cumulative rate of nitrite nitrogen reach 50% or more, so as to realize short-range nitrification acclimation; Step 2: Calculate the water inlet split ratio r according to the water inlet parameters of the water inlet pipe 15, and transport the sewage to the first hypoxic aerobic pool 1 and the anoxic pool 2 through the water inlet pipe 15 according to the water inlet split ratio r; Step 3: A portion of the sewage passes through the first hypoxic aerobic tank 1 for a short-range nitrification reaction, and then enters the anoxic tank 2; Step 4: The sewage after the short-cut nitrification reaction is mixed with another part of the sewage transported to the anoxic tank 2 by the water inlet pipe 15 to carry out a short-cut denitrification reaction and a phosphorus release process of polyphosphate bacteria; Step 5: The wastewater after the reaction in step 4 is transported to the second aerobic tank 3, and the dissolved oxygen concentration in the second aerobic tank 3 is controlled to be 1.5-2 mg / L to carry out the phosphorus absorption process and organic matter removal, and then transported to the sedimentation tank 13 to obtain the treated water.

[0030] Preferably, the step 1 is specifically as follows: taking activated sludge from a conventional process and inoculating it into a first hypoxic aerobic tank 1, ventilating the activated sludge for 1 day to activate the activity of the activated sludge, controlling the dissolved oxygen concentration of the first hypoxic aerobic tank 1 to be 0.5-0.9 mg / L, and the hydraulic retention time to be 2-4 h, and continuously monitoring the nitrite nitrogen concentration in the effluent of the first hypoxic aerobic tank 1. When the cumulative rate of nitrite nitrogen reaches 50% or more, it is considered that the short-range nitrification acclimation is completed.

[0031] Preferably, the calculation method of the water inlet split ratio r in step 2 is: the water inlet split ratio r refers to the proportion of sewage entering the first hypoxic aerobic pool 1 to the total water inlet of the water inlet pipe 15, and the calculation formula of the water inlet split ratio r is:

[0032] Where: —— ;

[0033] ——NH3-N concentration in influent, mg / L; —— ; ——

[0034] ——Removal rate of organic matter in the first hypoxic aerobic pool; The calculation formula for the organic matter removal rate of the first hypoxic aerobic pool is:

[0035] Where: —— ,℃; —— ; —— ; ——

[0036] —— ; —— , d -1 ; ——Hydraulic retention time of the first hypoxic aerobic tank, h; ——sludge concentration, mg / L; ——MLVSS / MLSS; ——Influent COD concentration, mg / L.

[0037] Preferably, the step 3 is specifically as follows: after the inlet water split ratio r is calculated, the sewage is transported to the first hypoxic aerobic tank 1 through the water inlet pipe 15, and a short-range nitrification reaction is carried out to generate nitrite nitrogen. The first hypoxic aerobic tank 1 is provided with a stirring device 4, and the dissolved oxygen concentration in the sewage is controlled at 0.5-0.9 mg / L by a rotor flowmeter, the hydraulic retention time is controlled at 2-4 h, the sludge concentration is maintained at 3000-5000 mg / L, and some organic matter is removed. The sewage after the reaction enters the anoxic tank 2.

[0038] Preferably, step 4 is specifically as follows: the effluent from the first hypoxic aerobic tank 1 is transported to the bottom of the anoxic tank 2, and an anoxic tank sewage inlet 11 is provided at the bottom of the anoxic tank 2. According to the calculation of the inlet diversion ratio r, another part of the sewage is directly transported to the anoxic tank 2 through the inlet pipe 15. The anoxic tank 2 is provided with a stirring device 4, the hydraulic retention time is controlled at 3 to 5 hours, and the sludge concentration is maintained at 3000 to 5000 mg / L. The microorganisms in the anoxic tank 2 use the residual organic matter in the reaction of the first hypoxic aerobic tank 1 and the organic matter entering the sewage through the anoxic tank sewage inlet 11 as an electron donor, and the first hypoxic aerobic tank 1 reacts to generate nitrite nitrogen as an electron acceptor to carry out a short-range denitrification reaction, and the polyphosphate bacteria release phosphorus process is carried out at the same time. The sewage after the reaction of the anoxic tank 2 enters the second aerobic tank 3.

[0039] Preferably, the step 5 is specifically as follows: the effluent from the anoxic tank 2 is transported to the bottom of the second aerobic tank 3, an aeration pipe 8 is provided at the bottom of the second aerobic tank 3, the dissolved oxygen concentration in the water is controlled at 1.5-2 mg / L by a rotor flowmeter, the hydraulic retention time is controlled at 2-4 h, the sludge concentration is maintained at 3000-5000 mg / L, the microorganisms in the second aerobic tank 3 deeply remove organic matter and nitrogen and complete the phosphorus absorption process of polyphosphate bacteria, and the sewage after the reaction enters the sedimentation tank 13.

[0040] Preferably, the sedimentation tank 13 is provided with a sludge return system, the sludge return ratio is controlled at 70% to 100%, and the sludge is returned to the bottom of the first hypoxic aerobic tank 1 through the sludge return port 10 .

[0041] Example 1 This embodiment includes the following steps: Step 1, inoculation sludge: The sludge inoculated in the short-term nitrification acclimation stage is the activated sludge of the traditional water treatment process, which is taken from the return sludge of a sewage treatment plant, and is put into the SLOAO reactor after the impurities are sieved out by a 2mm sieve. The sludge concentration of the reactor after inoculation is 4000mg / L. In the acclimation stage, the reactor inlet water adopts artificial water distribution, in which COD, NH3-N, TN, TP are 400mg / L, 45mg / L, 50mg / L and 7mg / L respectively. The dissolved oxygen concentration of the first hypoxic aerobic pool 1 is controlled at 0.7mg / L, and the hydraulic retention time is 3h. After continuous monitoring on the 28th day, short-term nitrification acclimation is achieved, and the cumulative rate of nitrite nitrogen in the effluent of the first hypoxic aerobic pool 1 is 61%.

[0042] Step 2, take the sewage after the grit tank of the actual sewage treatment plant, the BOD5 / COD of the sewage is 0.56, the BOD5 / TN is 2.95~3.82, COD, NH3-N, TN, TP are 220~280mg / L, 37.9~48.1mg / L, 41.3~52.9mg / L and 4.8~7mg / L respectively, by calculation, the organic matter removal rate of the first hypoxic aerobic tank 1 is 51%, the inlet water split ratio r is 0.69~0.81, the inlet water split ratio is 0.75, and the sludge return ratio is 80%.

[0043] Step 3, according to the water split ratio r, the sewage is passed into the first hypoxic aerobic tank 1 for short-range nitrification reaction, and then enters the anoxic tank 2; Step 4, the anoxic pool 2 is mixed with another part of the sewage transported to the anoxic pool 2 by the water inlet pipe 15, and a short-range denitrification reaction and a phosphorus release process of polyphosphate bacteria are carried out; The wastewater after the reaction in step 5 and step 4 is transported to the second aerobic tank 3, and the dissolved oxygen concentration in the second aerobic tank 3 is controlled to be 1.5-2 mg / L to carry out the phosphorus absorption process and organic matter removal, and then transported to the sedimentation tank 13 to obtain the treated water.

[0044] like Figure 2 As shown, NAR is NO2 - -N accumulation rate, NO2 in the effluent of the first hypoxic aerobic pool 1 - The average accumulation rate of -N was 50.6%, indicating that some short-range nitrification reactions were successfully achieved in the first hypoxic aerobic pool 1; Figure 3 As shown, after the actual sewage has been continuously reacted for 20 days after the SLOAO process has stabilized, the average COD concentration of the effluent from the sedimentation tank without the addition of an external carbon source is 23.96 mg / L, the average NH3-N concentration is 0.183 mg / L, and the average TN concentration is 8.29 mg / L, which meets the quasi-Class IV emission standards of the sewage treatment plant, and the average TP concentration is 0.82 mg / L.

[0045] Example 2 Taking actual campus domestic sewage, after pretreatment, the sewage BOD5 / COD is 0.47, BOD5 / TN is 2.42~3.19, COD, NH3-N, TN, TP are 276.80~403.37mg / L, 41.05~52.14mg / L, 49.51~59.81mg / L and 4.97~6.14mg / L respectively, and the inlet water diversion ratio r is 0.80.

[0046] like Figure 4 As shown, the effluent NO2 of the first hypoxic aerobic pool 1 - The average accumulation rate of -N was 56%, indicating that some short-range nitrification reactions were successfully achieved in the first hypoxic aerobic pool 1; Figure 5 As shown, after the actual sewage was subjected to continuous reaction for 36 days in the SLOAO process with stable operation of sludge acclimation in step 1, the average COD concentration of the effluent from the sedimentation tank without the addition of external carbon source was 24.68 mg / L, the average NH3-N concentration was 0.247 mg / L, and the average TN concentration was 10.82 mg / L, which met the Level A standard of the pollutant emission standard for urban sewage treatment plants (GB189182002), and the average TP concentration was 0.95 mg / L.

[0047] The present application provides a device for treating urban low carbon nitrogen ratio sewage by SLOAO process, referred to as SLOAO process, which is mainly a process with short-range nitrification and denitrification and sewage water diversion as the core. The SLOAO process includes a first low oxygen aerobic tank 1, an anoxic tank 2, and a second aerobic tank 3 in the direction of water flow, and a sedimentation tank 13 and a sludge return system are provided in the device.

[0048] The present application provides a device and method for treating urban low carbon-nitrogen ratio sewage using the SLOAO process, which has high denitrification efficiency, low aeration energy consumption, no internal reflow and no need for additional carbon source addition, significantly reducing energy consumption during sewage treatment, reducing overall sewage treatment costs, and improving treatment efficiency and economic benefits.

[0049] The method of the application allows a portion of the sewage to undergo a short-range nitrification reaction in the first low-oxygen aerobic tank, and the nitrite nitrogen generated by the reaction directly enters the anoxic tank to undergo a short-range denitrification reaction with another portion of the sewage, eliminating the step of reflux of the nitrification liquid in the traditional process, abandoning the traditional denitrification pre-denitrification setting, and reducing the energy consumption of the reflux pump.

[0050] This application proposes to divert sewage inflow, clearly calculates the inflow diversion ratio, fully utilizes the carbon source in the raw sewage, meets the carbon source needs of different spatial bacterial communities, and achieves low / zero carbon source addition.

[0051] The first low oxygen aerobic pool of the present application realizes short-range nitrification under low dissolved oxygen conditions, reduces the aeration volume and the carbon source demand in the denitrification process, and realizes efficient nitrogen removal.

[0052] The sludge of the present application is returned to the first low oxygen aerobic tank to quickly activate the sludge activity and enhance the removal effect of pollutants.

[0053] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present application.

[0054] Many other changes and modifications can be made without departing from the concept and scope of the present application.It should be understood that the present application is not limited to specific embodiments, and the scope of the present application is defined by the appended claims.

Claims

1. A device for treating urban low carbon nitrogen ratio sewage by SLOAO process, characterized in that: The invention comprises a first hypoxic aerobic pool (1), an anoxic pool (2), a second aerobic pool (3) and a sedimentation pool (13) which are connected in sequence, and a control component. The first hypoxic aerobic pool (1) is provided with a sewage inlet (7) at the bottom of the water inlet side, and the sewage inlet (7) is connected to a water inlet pipe (15) through a pipeline. The first hypoxic aerobic pool (1) is provided with a first outlet (5) at the water outlet side, and the first outlet (5) is connected to the anoxic pool (2). The anoxic pool (2) is also provided with a second outlet (14) at the water outlet side, and the second outlet (14) is connected to the second aerobic pool (3). The water outlet side of the second aerobic pool (3) is connected to the sedimentation pool. (13), the planes where the first water outlet (5) and the second water outlet (14) are located are higher than the plane where the sewage inlet (7) is located, the bottom of the anoxic tank (2) is also provided with an anoxic tank sewage inlet (11), and the anoxic tank sewage inlet (11) is also connected to the water inlet pipe (15) through a pipeline, the first hypoxic aerobic tank (1) and the anoxic tank (2) are both provided with a stirring device (4), the bottoms of the first hypoxic aerobic tank (1) and the second aerobic tank (3) are both provided with an aeration pipe (8), the aeration pipe (8) is externally connected to a blower (9), and the stirring device (4) and the blower (9) are respectively electrically connected to the control component; The dissolved oxygen concentration of the first hypoxic aerobic tank (1) is 0.5-0.9 mg / L, and the dissolved oxygen concentration of the second aerobic tank (3) is 1.5-2 mg / L. The first hypoxic aerobic tank (1) is inoculated with activated sludge. The activated sludge makes the cumulative rate of nitrite nitrogen in the part of sewage entering from the sewage inlet (7) reach 50% or more, so as to achieve short-term nitrification and domestication. The sewage after the short-term nitrification reaction is mixed with another part of sewage entering the anoxic tank (2) from the sewage inlet (11) of the anoxic tank to undergo a short-term denitrification reaction and a phosphorus release process by polyphosphate bacteria. The sewage after the reaction is transported to the second aerobic tank (3) to undergo a phosphorus absorption process and organic matter removal, and then transported to the sedimentation tank (13) to obtain a treated water body.

2. The device for treating urban low carbon-nitrogen ratio sewage by SLOAO process according to claim 1, characterized in that: The sewage inlet (7) and the anoxic tank sewage inlet (11) are both connected to the water inlet pipe (15) via the water inlet pump (6), and the water inlet pump (6) is electrically connected to the control component.

3. The device for treating urban low carbon-nitrogen ratio sewage by SLOAO process according to claim 1, characterized in that: The bottom of the sedimentation tank (13) is connected to the sludge return port (10) at the bottom of the first hypoxic aerobic tank (1) via a pipeline, and a sludge return pump (12) is provided on the pipeline. The sludge return pump (12) is electrically connected to the control component.

4. A method for treating urban low carbon nitrogen ratio sewage by SLOAO process, characterized in that: The device for treating urban low carbon-nitrogen ratio sewage by using a SLOAO process as described in any one of claims 1 to 3 is used for sewage treatment, specifically comprising the following steps: Step 1: sludge inoculation and acclimatization; inoculating the activated sludge into the first hypoxic aerobic tank (1), acclimatizing the activated sludge, controlling the dissolved oxygen concentration of the first hypoxic aerobic tank (1) to be 0.5-0.9 mg / L, and making the cumulative rate of nitrite nitrogen reach 50% or more, so as to achieve short-range nitrification acclimatization; Step 2: Calculate the water inlet split ratio r according to the water inlet parameters of the water inlet pipe (15), and transport the sewage to the first low oxygen aerobic pool (1) and the anoxic pool (2) through the water inlet pipe (15) according to the water inlet split ratio r; Step 3: A portion of the sewage passes through the first hypoxic aerobic tank (1) for a short-range nitrification reaction and then enters the anoxic tank (2); Step 4: The sewage after the short-cut nitrification reaction is mixed with another part of the sewage transported to the anoxic tank (2) through the water inlet pipe (15) to carry out a short-cut denitrification reaction and a phosphorus release process by polyphosphate bacteria; Step 5: The wastewater after the reaction in step 4 is transported to the second aerobic tank (3), and the dissolved oxygen concentration in the second aerobic tank (3) is controlled to be 1.5-2 mg / L to carry out the phosphorus absorption process and organic matter removal, and then transported to the sedimentation tank (13) to obtain the treated water.

5. The method for treating urban low carbon-nitrogen ratio sewage by SLOAO process according to claim 4, characterized in that: The step 1 specifically comprises: taking activated sludge from a conventional process and inoculating it into a first hypoxic aerobic tank (1), exposing the activated sludge for one day to activate the activity of the activated sludge, controlling the dissolved oxygen concentration of the first hypoxic aerobic tank (1) to be 0.5-0.9 mg / L, and the hydraulic retention time to be 2-4 hours, and continuously monitoring the nitrite nitrogen concentration in the effluent of the first hypoxic aerobic tank (1). When the nitrite nitrogen accumulation rate reaches 50% or more, it is considered that the short-range nitrification acclimation is completed.

6. The method for treating urban low carbon-nitrogen ratio sewage by SLOAO process according to claim 4, characterized in that: The calculation method of the water inlet split ratio r in step 2 is as follows: the water inlet split ratio r refers to the ratio of the sewage entering the first hypoxic aerobic pool (1) to the total water inlet volume of the water inlet pipe (15). The calculation formula of the water inlet split ratio r is: ； Where: —— ； ——NH3-N concentration in influent, mg / L; —— ； —— ； ——Removal rate of organic matter in the first hypoxic aerobic pool; The calculation formula for the organic matter removal rate of the first hypoxic aerobic pool is: ； Where: —— ，℃； —— ； —— ； —— ； —— ； —— ，d -1 ； ——Hydraulic retention time of the first hypoxic aerobic tank, h; ——Sludge concentration, mg / L; ——MLVSS / MLSS; ——Influent COD concentration, mg / L.

7. The method for treating urban low carbon-nitrogen ratio sewage by SLOAO process according to claim 6, characterized in that: The step 3 specifically comprises: after the inlet water split ratio r is calculated, the sewage is transported to the first hypoxic aerobic tank (1) through the inlet pipe (15) to undergo a short-range nitrification reaction to generate nitrite nitrogen; the first hypoxic aerobic tank (1) is provided with a stirring device (4); the dissolved oxygen concentration in the sewage is controlled at 0.5 to 0.9 mg / L by a rotor flow meter; the hydraulic retention time is controlled at 2 to 4 h; the sludge concentration is maintained at 3000 to 5000 mg / L; part of the organic matter is removed; and the sewage after the reaction enters the anoxic tank (2).

8. The method for treating urban low carbon-nitrogen ratio sewage by SLOAO process according to claim 6, characterized in that: The step 4 specifically comprises: the effluent of the first hypoxic aerobic tank (1) is transported to the bottom of the anoxic tank (2); at the same time, an anoxic tank sewage inlet (11) is provided at the bottom of the anoxic tank (2); according to the calculation of the inlet water split ratio r, another part of the sewage is directly transported to the anoxic tank (2) through the inlet pipe (15); a stirring device (4) is provided in the anoxic tank (2); the hydraulic retention time is controlled at 3 to 5 hours; the sludge concentration is maintained at 3000 to 5000 mg / L; the microorganisms in the anoxic tank (2) use the residual organic matter in the reaction of the first hypoxic aerobic tank (1) and the organic matter in the sewage entering the anoxic tank sewage inlet (11) as electron donors; the nitrite nitrogen generated by the reaction in the first hypoxic aerobic tank (1) is used as an electron acceptor to carry out a short-range denitrification reaction; at the same time, the phosphorus release process of polyphosphate bacteria is carried out; the sewage after the reaction in the anoxic tank (2) enters the second aerobic tank (3).

9. The method for treating urban low carbon-nitrogen ratio sewage by SLOAO process according to claim 4, characterized in that: The step 5 specifically comprises: the effluent from the anoxic tank (2) is transported to the bottom of the second aerobic tank (3); an aeration pipe (8) is provided at the bottom of the second aerobic tank (3); the dissolved oxygen concentration in the water is controlled at 1.5 to 2 mg / L by a rotor flow meter; the hydraulic retention time is controlled at 2 to 4 hours; the sludge concentration is maintained at 3000 to 5000 mg / L; the microorganisms in the second aerobic tank (3) deeply remove organic matter and nitrogen and complete the phosphorus absorption process of polyphosphate bacteria; and the wastewater after the reaction enters the sedimentation tank (13).

10. The method for treating urban low carbon-nitrogen ratio sewage by SLOAO process according to claim 9, characterized in that: The sedimentation tank (13) is provided with a sludge return system, and the sludge return ratio is controlled at 70% to 100%. The sludge is returned to the bottom of the first hypoxic aerobic tank (1) through the sludge return port (10).

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