Improved continuous flow AO device with sequencing batch regulation mechanism

Abstract

The invention relates to the technical field of sewage treatment, and particularly discloses an improved continuous flow AO device with a sequencing batch regulation mechanism, and a flow regulation unit is configured between a raw water inlet bucket and an anoxic reaction tank; an adjusting device is arranged between the anoxic reaction tank and the aerobic reaction tank; a filler is arranged in the anoxic reaction tank; the aerobic reaction tank is provided with an aeration device; a sludge return loop is arranged between the secondary sedimentation tank and the anoxic reaction tank; a nitrification liquid backflow loop is arranged between the aerobic reaction tank and the anoxic reaction tank; according to the device, sequencing batch operation is utilized, and a large number of anoxic zones are formed in the aerobic reaction tank to create conditions for synchronous nitrification and denitrification; meanwhile, in a nitrate nitrogen and ammonia nitrogen coexistence environment in the anoxic reaction tank, sequencing batch operation strengthens the operation efficiency of the system, and shorter anoxic reaction time promotes nitrate nitrogen to be reduced into nitrite nitrogen; the filler is combined to provide a carrier for the growth of anaerobic ammonium oxidation bacteria, so that the enrichment of the anaerobic ammonium oxidation bacteria is realized, and the denitrification contribution of short-cut denitrification coupled anaerobic ammonium oxidation is promoted.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to an improved continuous flow AO device with a sequencing batch control mechanism. Background Technology

[0002] In mainstream wastewater treatment processes, there are still many technical challenges in achieving efficient coupling of short-cut denitrification and anaerobic ammonia oxidation in anoxic reactors, while simultaneously enhancing simultaneous nitrification and denitrification in aerobic reactors to improve nitrogen removal efficiency. Summary of the Invention

[0003] Addressing the challenges of starting up short-cut denitrification coupled with anaerobic ammonium oxidation (AO) and low carbon source utilization in current deep denitrification of urban domestic wastewater with low carbon-to-nitrogen ratios, this invention proposes an improved continuous-flow AO device with a sequencing batch reactor (SBR) control mechanism. The SBR operation creates numerous anoxic zones in the aerobic reaction tank, providing conditions for simultaneous nitrification and denitrification, and fully utilizing the organic matter in the wastewater. Simultaneously, the coexistence of nitrate and ammonia nitrogen in the anoxic reaction zone, coupled with the SBR operation, enhances system efficiency. The shorter anoxic reaction time promotes the reduction of nitrate nitrogen to nitrite nitrogen. Combined with the packing material, it provides a carrier for the growth of anaerobic ammonium oxidizing bacteria, thereby enriching these bacteria and promoting the denitrification contribution of short-cut denitrification coupled with anaerobic ammonium oxidation.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] An improved continuous flow AO device with a sequential batch control mechanism includes a raw water inlet tank, an anoxic reaction tank, an aerobic reaction tank, a secondary sedimentation tank, and a control device.

[0006] The raw water inlet tank, anoxic reaction tank, aerobic reaction tank, and secondary sedimentation tank are connected in sequence.

[0007] A flow regulation unit is configured between the raw water inlet tank and the anoxic reaction tank to regulate the fluctuation of the inlet flow rate of the anoxic reaction tank.

[0008] An adjustment device is provided between the anoxic reaction tank and the aerobic reaction tank to regulate the drainage flow of the anoxic tank and control the flow of the mixed liquid from the anoxic reaction tank to the aerobic reaction tank.

[0009] The anoxic reaction tank is equipped with polyethylene suspended ball packing material.

[0010] The aerobic reaction tank has a matrix-type multi-point aeration device.

[0011] A sludge return loop is provided between the secondary sedimentation tank and the anoxic reaction tank.

[0012] A nitrification liquid reflux circuit is provided between the aerobic reaction tank and the anoxic reaction tank.

[0013] The regulating device is electrically connected to the control device, and the control device is used at least to control the opening and closing of the regulating device.

[0014] When the regulating device is in the off state, an environment in which ammonia nitrogen and nitrate nitrogen coexist is formed in the anoxic reaction tank.

[0015] When the regulating device is in the open state, the sewage in the anoxic reaction tank flows to the aerobic reaction tank, and a pulse disturbance is formed in the aerobic reaction tank, causing the dissolved oxygen in the aerobic tank to drop sharply and turbulence to be generated simultaneously, cutting the large flocs of sludge into micro flocs.

[0016] In at least one embodiment of the improved continuous flow AO device with a sequential batch control mechanism provided in this disclosure, the control device is a pneumatic control valve.

[0017] In at least one embodiment of the improved continuous flow AO device with a sequencing batch control mechanism provided in this disclosure, the aerobic reaction tank has a monitoring component for monitoring one or more of dissolved oxygen data, pH data, and temperature data of the wastewater in the aerobic reaction tank.

[0018] The monitoring component and the matrix multi-point aeration device are both electrically connected to the control device. The control device is also used to control the matrix multi-point aeration device and the adjustment device based on the monitoring data of the monitoring component.

[0019] In at least one embodiment of the improved continuous flow AO device with a sequential batch control mechanism provided in this disclosure, the opening cycle of the control device is 9 minutes, or the closing cycle of the control device is 18 minutes.

[0020] The improved continuous flow AO device with a sequential batch control mechanism provided in at least one embodiment of this disclosure further includes a stirrer for stirring the wastewater in the anoxic reaction tank.

[0021] In the improved continuous flow AO device with a sequential batch control mechanism provided in at least one embodiment of this disclosure, the secondary settling tank is an elliptical inclined tube settling structure.

[0022] In at least one embodiment of the improved continuous flow AO device with a sequential batch control mechanism provided in this disclosure, the flow regulation unit includes an electromagnetic flow meter and a variable frequency inlet pump.

[0023] The electromagnetic flowmeter and the variable frequency water pump are both electrically connected to the control device.

[0024] In at least one embodiment of the present disclosure, an improved continuous flow AO apparatus with a sequential batch control mechanism is provided, wherein the nitration reflux loop includes a first pipe and a nitration reflux pump.

[0025] The sludge return circuit includes a second pipe and a sludge return pump.

[0026] Both the nitrification liquid return pump and the sludge return pump are electrically connected to the control device.

[0027] The beneficial effects of this invention are as follows:

[0028] 1) Organic matter in urban sewage is stored as an internal carbon source by denitrifying polysaccharide bacteria in the pre-anaerobic reactor and used for simultaneous nitrification and denitrification in the aerobic reactor, so that the organic carbon source in the raw water can be fully utilized and energy can be saved.

[0029] 2) Sequencing batch reactor (SBR) operation combined with the addition of packing biofilm enhances NO3 reduction in the anoxic zone. - Reduced to NO2 - , created an NH4 + NO2 - and NO3 - The long-term coexistence environment, coupled with the biofilm in the packing material providing a growth carrier for the enrichment of anaerobic ammonia-oxidizing bacteria, successfully achieved the self-enrichment of anaerobic ammonia oxidation. This increased the proportion of autotrophic denitrification in the system and saved energy.

[0030] 3) The sequential batch operation mode allows the sludge mixture to settle sufficiently in the secondary sedimentation tank, promoting the separation of sludge and water in the secondary sedimentation tank and making the process effluent clearer. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the overall structure of an improved continuous flow AO device with a sequential batch control mechanism according to the present invention.

[0033] Figure 2 This is a schematic diagram of the overall structure of an improved continuous flow AO device with a sequential batch control mechanism according to the present invention.

[0034] In the picture:

[0035] 10. Raw water inlet tank; 11. Flow regulation unit;

[0036] 20. Anoxic reaction tank; 21. Regulating device;

[0037] 30. Aerobic reaction tank; 31. Monitoring components; 32. Matrix multi-point aeration device;

[0038] 40. Secondary sedimentation tank;

[0039] 50. Control device;

[0040] 60. Mixer;

[0041] 70. Nitrification liquid reflux pump;

[0042] 80. Sludge return pump. Detailed Implementation

[0043] The technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments, not all embodiments.

[0044] Example

[0045] like Figure 1 and 2 As shown, this embodiment provides an improved continuous flow AO device with a sequential batch control mechanism, including a raw water inlet tank 10, an anoxic reaction tank 20, an aerobic reaction tank 30, a secondary sedimentation tank 40, a control device 50, and a stirrer 60.

[0046] Specifically, the raw water inlet tank 10, the anoxic reaction tank 20, the aerobic reaction tank 30, and the secondary sedimentation tank 40 are connected in sequence via pipelines. The volume ratio of the anoxic reaction tank to the aerobic reaction tank is 1:2.

[0047] In this embodiment, a flow regulating unit 11 is provided between the raw water inlet tank 10 and the anoxic reaction tank 20. The flow regulating unit 11 is used to regulate the fluctuation of the inlet flow of the anoxic reaction tank 20.

[0048] Specifically, the control device 50 controls the influent flow rate of the anoxic reaction tank 20 through a PID algorithm, so that the influent flow rate fluctuation is ≤±5%.

[0049] Specifically, the flow regulating unit 11 includes a first electromagnetic flow meter and a variable frequency water pump, both of which are electrically connected to the control device 50.

[0050] In this embodiment, an adjustment device 21 is provided between the anoxic reaction tank 20 and the aerobic reaction tank 30. The adjustment device 21 is used to regulate the drainage flow of the anoxic tank and control the flow of the mixed liquid from the anoxic reaction tank 20 to the aerobic reaction tank 30.

[0051] Specifically, the regulating device 21 adopts a pneumatic regulating valve.

[0052] For example, the pneumatic regulating valve uses a 316L stainless steel valve body and an EPDM rubber diaphragm, with a response time of 2.5s, and is controlled by the control device 50 to operate in a 9min opening / 18min closing cycle.

[0053] For example, the drainage flow rate is 0.8m. 3 / h, after storing water for 18 minutes during the valve closure period, 1 / 3 of the 20L volume of the anoxic tank is emptied within 9 minutes during the valve opening period, i.e., the pulse flow rate is approximately 0.0011m³ / h. 3 / s).

[0054] In this embodiment, a polyethylene suspended ball packing material (not shown) is installed in the anoxic reaction tank 20.

[0055] Specifically, the polyethylene suspended ball packing has a diameter of 25 mm, a porosity of ≥90%, and a filling rate of 20%-30%.

[0056] In this embodiment, the stirrer 60 is used to stir the wastewater in the anoxic reaction tank 20.

[0057] For example, the agitator 60 uses a three-bladed swept impeller with a constant rotation speed of 80 rpm and a mixture flow rate of 0.18 m / s.

[0058] In this embodiment, the aerobic reaction tank 30 has a matrix-type multi-point aeration device 32.

[0059] For example, the aeration discs of the matrix-type multi-point aeration device are spaced 350mm apart, arranged in 4 rows × 3 columns, totaling 12 discs. Each aeration disc is connected to a gas flow meter, and the aeration rate is adjusted in real time by the control device 50 to maintain dissolved oxygen at 1.4-1.6 mg / L, decreasing to 0.8-1.0 mg / L after a pulse. The air pump of the matrix-type multi-point aeration device is located outside the aerobic reaction tank 30, and the air pump is connected to the aeration discs through a pipeline.

[0060] In this embodiment, the aerobic reaction tank 30 has a monitoring component 31, which is used to monitor the dissolved oxygen data, pH data and temperature data of the wastewater in the aerobic reaction tank 30.

[0061] For example, the monitoring component 31 uses a WTW monitor with a monitoring frequency of 1 time / min, a dissolved oxygen detection accuracy of ±0.1 mg / L, and a pH detection accuracy of ±0.05.

[0062] In this embodiment, the secondary sedimentation tank 40 adopts an elliptical inclined tube structure, wherein the major axis of the secondary sedimentation tank 40 is 1.2m, the minor axis of the secondary sedimentation tank 40 is 0.8m, the inclination angle of the inclined tube of the secondary sedimentation tank 40 is 63°, and the diameter of the tube of the secondary sedimentation tank 40 is 60mm.

[0063] In this embodiment, a sludge return loop is provided between the secondary sedimentation tank 40 and the anoxic reaction tank 20; a nitrification liquid return loop is provided between the aerobic reaction tank 30 and the anoxic reaction tank 20.

[0064] Specifically, the nitrification liquor return circuit includes a first pipe and a nitrification liquor return pump 70, and a Venturi flow meter (not shown) is installed on the first pipe; the sludge return circuit includes a second pipe and a sludge return pump 80, and a second electromagnetic flow meter (not shown) is installed on the second pipe; the nitrification liquor return pump 70, the sludge return pump 80, the Venturi flow meter and the second electromagnetic flow meter are all electrically connected to the control device 50.

[0065] Specifically, the control device 50 uses a PLC.

[0066] During the nitrification liquid reflux, the reflux ratio is controlled at 200% by the Venturi flow meter and the nitrification liquid reflux pump 70, and the actual reflux flow rate is twice the inlet flow rate.

[0067] During sludge recirculation, the second electromagnetic flowmeter is used for real-time monitoring to maintain a recirculation ratio of 100% and a recirculated sludge concentration of 3200 mg / L.

[0068] The operation flow of the improved continuous flow AO device with a sequential batch control mechanism in the embodiments will be disclosed below.

[0069] With a COD concentration of 220 mg / L and NH4 + Taking septic tank wastewater with a -N concentration of 60 mg / L as an example, the operation stages are as follows:

[0070] 1. Simultaneous nitrification-denitrification and anaerobic ammonia oxidizing bacteria enrichment stage (days 1-20)

[0071] Vaccination and Initiation: Vaccination A 2 / O process waste sludge (MLSS = 3000 mg / L), control sludge age for 28 days, maintain sludge concentration at 2800 mg / L.

[0072] Pneumatic regulating valve control:

[0073] Valve closure period (18 min): NH4 forms in the anoxic tank. + -N (12 mg / L) and NO3 - In an environment where -N (8 mg / L) coexisted, the combined packing material promoted the attachment of anaerobic ammonia-oxidizing bacteria, and their abundance increased from an initial 0.5% to 8.2% on day 20.

[0074] Valve opening period (9 min): Pulsed water flow at 0.8 m 3 As the flow rate of oxygen increases by 1.5 mg / L to 0.9 mg / L in the aerobic tank, the dissolved oxygen level drops sharply from 1.5 mg / L to 0.9 mg / L, creating an anoxic microzone that accounts for 35% of the total. This increases the efficiency of simultaneous nitrification and denitrification to 48%.

[0075] Results data:

[0076] The nitrogen removal contribution rate in the anoxic tank was 30.51±2.87%, and in the aerobic tank it was 51.09±3.26%, with a total nitrogen removal rate of 72% and a carbon source utilization rate of 78%.

[0077] 2. Short-cut denitrification coupled with anaerobic ammonium oxidation for efficient nitrogen removal (days 21-40)

[0078] Biological community evolution: The abundance of anaerobic ammonia oxidizing bacteria increased to 16.5% (dominated by Candidatus Brocadia), and short-range denitrification produced NO2. - -N accounted for 68%.

[0079] Optimization of regulatory strategies:

[0080] The valve closing period was shortened to 15 minutes, the valve opening period was extended to 12 minutes, the pulse disturbance was strengthened, and the proportion of anoxic micro-zones in the aerobic tank was increased to 42%.

[0081] Dissolved oxygen in the aerobic tank was maintained at 1.2 mg / L, which promoted the accumulation of nitrite (NO2). - -N / NO3 - -N≥0.6).

[0082] Results data:

[0083] The nitrogen removal contribution rate in the anoxic tank was 58.09±3.26%, and in the aerobic tank it was 27.51±2.87%, with the total nitrogen removal rate exceeding 85% and the anaerobic ammonia oxidation pathway contributing 38%.

[0084] 3. Stable operation phase (starting from day 41)

[0085] Process parameters:

[0086] The hydraulic retention time was 10 hours, with 3.3 hours in the anoxic tank and 6.7 hours in the aerobic tank. The sludge age was 42 days, and the sludge concentration was 3100 mg / L.

[0087] The pneumatic regulating valve operates stably in a 9min / 18min cycle, and the PLC automatically adjusts the aeration volume (adjustment range ±15%) based on the WTW data.

[0088] Outflow water quality:

[0089] COD concentration was 25±5 mg / L, NH4+ + -N concentration was 1.2±0.3 mg / L, and TN concentration was 4.8±0.6 mg / L.

[0090] Economic indicators:

[0091] The sludge yield is 0.18 kg VSS / kg COD, which is 44% lower than that of the traditional AO process;

[0092] The aeration rate is 1.2m³. 3 / h, energy consumption is 0.35kW·h / m 3 This saves 23%.

[0093] Key technology verification

[0094] Pulse effect of pneumatic control valve:

[0095] The internal carbon source (PHA content of 120 mg / L) stored during the valve closure period is utilized by denitrifying bacteria in the aerobic tank during the valve opening period, and the carbon source utilization rate is 22% higher than that of the continuous flow process.

[0096] Pulse perturbation reduced the average particle size of sludge flocs from 280 μm to 140 μm, increased the specific surface area by 53%, and significantly improved the mass transfer efficiency.

[0097] The reinforcing effect of combined packing materials:

[0098] The anaerobic ammonia-oxidizing bacteria activity in the inner layer (thickness > 2 mm) of the packing biofilm reached 0.05 kgN / (m³). 3 ·d), is 3 times that of suspended sludge.

[0099] Secondary sedimentation tank performance:

[0100] The sequential batch influent / effluent strategy extends sludge settling time to 1.8 times that of traditional processes, improves the clarity of the sludge-water interface, and increases the solids content of the returned sludge by 12%.

[0101] Although embodiments of this application have been shown and described above, the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be conceived without inventive effort should be covered within the scope of protection of this invention. Unless expressly stated otherwise, no element, action or instruction used herein should be construed as critical or necessary.

Claims

1. An improved continuous flow AO device with a sequential batch control mechanism, characterized in that, include: Raw water inlet tank, anoxic reaction tank, aerobic reaction tank, secondary sedimentation tank and control device; The raw water inlet tank, the anoxic reaction tank, the aerobic reaction tank, and the secondary sedimentation tank are connected in sequence. A flow regulation unit is configured between the raw water inlet tank and the anoxic reaction tank to regulate the fluctuation of the inlet flow rate of the anoxic reaction tank. An adjustment device is provided between the anoxic reaction tank and the aerobic reaction tank to regulate the drainage flow of the anoxic tank. The anoxic reaction tank is equipped with polyethylene suspended ball packing material. The aerobic reaction tank has a matrix-type multi-point aeration device; A sludge return loop is provided between the secondary sedimentation tank and the anoxic reaction tank. A nitrification liquid reflux circuit is provided between the aerobic reaction tank and the anoxic reaction tank; The regulating device is electrically connected to the control device, and the control device is used at least to control the opening and closing of the regulating device; When the regulating device is in the off state, an environment in which ammonia nitrogen and nitrate nitrogen coexist is formed in the anoxic reaction tank; When the regulating device is in the open state, the sewage in the anoxic reaction tank flows to the aerobic reaction tank, and a pulse disturbance is formed in the aerobic reaction tank, causing the dissolved oxygen in the aerobic tank to drop sharply and turbulence to be generated simultaneously, cutting the large flocs of sludge into micro flocs.

2. The improved continuous flow AO device with a sequential batch control mechanism according to claim 1, characterized in that, The regulating device is a pneumatic regulating valve.

3. An improved continuous flow AO device with a sequential batch control mechanism according to claim 1, characterized in that, The aerobic reaction tank has a monitoring component, which is used to monitor one or more of the dissolved oxygen data, pH data, and temperature data of the wastewater in the aerobic reaction tank; The monitoring component and the matrix multi-point aeration device are both electrically connected to the control device. The control device is also used to control the matrix multi-point aeration device and the adjustment device based on the monitoring data of the monitoring component.

4. An improved continuous flow AO device with a sequential batch control mechanism according to claim 1, characterized in that, The opening cycle of the regulating device is 9 minutes, or the closing cycle of the regulating device is 18 minutes.

5. An improved continuous flow AO device with a sequential batch control mechanism according to claim 1, characterized in that, It also includes a stirrer for stirring the wastewater in the anoxic reaction tank.

6. An improved continuous flow AO device with a sequential batch control mechanism according to claim 1, characterized in that, The secondary sedimentation tank is an elliptical inclined tube sedimentation structure.

7. An improved continuous flow AO device with a sequential batch control mechanism according to claim 6, characterized in that, The flow regulation unit includes an electromagnetic flow meter and a variable frequency inlet pump; The electromagnetic flowmeter and the variable frequency water pump are both electrically connected to the control device.

8. An improved continuous flow AO device with a sequential batch control mechanism according to claim 1, characterized in that, The nitration reflux circuit includes a first pipe and a nitration reflux pump; The sludge return loop includes a second pipe and a sludge return pump; Both the nitrification liquid return pump and the sludge return pump are electrically connected to the control device.

Images