A combined denitrification process method and apparatus

Abstract

The application provides a combined denitrification process method and device, relates to the field of sewage biological treatment technology, and the method comprises the following steps: connecting flocculent sludge of a sewage plant into a one-step PN / A reactor, forming PN / A granular sludge under condition constraints, carrying out short-cut nitrification reaction by using the one-step PN / A reactor with the sludge state being granular sludge, and obtaining effluent of the PN / A reactor; introducing the effluent of the PN / A reactor into a PD reactor, adding an organic carbon source into the PD reactor for short-cut denitrification, obtaining effluent of the PD reactor and introducing the effluent into an Anammox reactor for deep denitrification, obtaining effluent of the Anammox reactor, and discharging the effluent by a effluent storage tank. The application solves the technical problems that a large amount of carbon source needs to be added in the nitrification and denitrification processes in the prior art, the treatment process has high energy consumption, and the amount of residual sludge is large, and the technical effects of reducing the amount of added organic carbon source, reducing the energy consumption of sewage denitrification and the amount of residual sludge are achieved.

Description

Technical Field

[0001] This application relates to the field of wastewater biological treatment technology, specifically to a combined denitrification process method and apparatus. Background Technology

[0002] In urban sewage and industrial wastewater treatment, nitrogen removal is a crucial step in ensuring the ecological safety of water bodies and preventing eutrophication. Conventional nitrogen removal processes typically employ a "nitrification-denitrification" pathway. First, under aerobic conditions, ammonia nitrogen is oxidized to nitrate or nitrite through nitrification. Then, in an anoxic environment, organic carbon sources act as electron donors to reduce nitrates back to nitrogen gas, achieving nitrogen removal. However, to maintain reaction efficiency and ensure total nitrogen removal, traditional nitrification / denitrification processes require large amounts of external organic carbon sources (such as sodium acetate and glucose), resulting in high reagent consumption. Furthermore, the nitrification process necessitates continuous aeration to maintain an aerobic environment, leading to high energy consumption and the generation of substantial amounts of excess sludge, further exacerbating the sludge treatment burden. Summary of the Invention

[0003] This application provides a combined denitrification process and apparatus, which solves the technical problems of existing technologies that require a large amount of external carbon source support for nitrification and denitrification processes, resulting in high energy consumption and large output of residual sludge. It achieves the technical effect of reducing the amount of organic carbon source added, reducing the energy consumption of wastewater denitrification and the amount of residual sludge.

[0004] In view of the above problems, this application provides a combined denitrification process, the method comprising: feeding flocculent sludge from a wastewater treatment plant into a one-step PN / A reactor according to a wastewater storage tank; acclimating the flocculent sludge in the one-step PN / A reactor into PN / A granular sludge under certain conditions; performing short-cut nitrification in the one-step PN / A reactor with granular sludge to obtain PN / A reactor effluent; introducing the PN / A reactor effluent into a PD reactor, adding an organic carbon source from a carbon source tank to the PD reactor for short-cut denitrification to obtain PD reactor effluent; introducing the PD reactor effluent into an Anammox reactor, performing deep denitrification on the PD reactor effluent according to the Anammox reactor to obtain Anammox reactor effluent; and discharging the Anammox reactor effluent from an effluent storage tank.

[0005] Preferably, the flocculent sludge in the one-step PN / A reactor is acclimated into PN / A granular sludge through condition constraints, including: setting a mixed liquor sludge concentration constraint of 2 to 4 g / L; setting a dissolved oxygen concentration constraint in the PN / A reactor of 0.2 to 0.5 mg / L; and using the mixed liquor sludge concentration constraint and the dissolved oxygen concentration constraint as the condition constraints to control the conversion of the flocculent sludge in the one-step PN / A reactor into granular sludge.

[0006] Preferably, the sludge volume index of the PN / A granular sludge is less than 50 mL / g.

[0007] Preferably, the effluent from the PN / A reactor is introduced into the PD reactor, and an organic carbon source is added from the carbon source tank to the PD reactor for short-cut denitrification to obtain the effluent from the PD reactor. This includes: obtaining the characteristic concentration of the effluent from the PN / A reactor, wherein the characteristic concentration is NO. 3- -N concentration; setting influent constraints for the PD reactor, wherein the influent constraints for the PD reactor are COD / NO. 3- -N value satisfies 2.5 to 3.0; with the influent constraint of the PD reactor as the control target, the organic carbon source concentration of the organic carbon source box is adjusted according to the characteristic concentration.

[0008] Preferably, the feed water to the Anammox reactor meets a predetermined mass concentration ratio constraint.

[0009] Preferably, the Anammox reactor includes an Anammox biofilm module, which is a nonwoven fabric filler with a length of 80 mm and a height of 150 mm.

[0010] Preferably, the one-step PN / A reactor is provided with a PN / A reaction zone and a PN / A precipitation zone.

[0011] Preferably, the PD reactor is provided with a PD reaction zone and a PD precipitation zone.

[0012] On the other hand, this application also provides a combined denitrification process device, the device comprising: a sludge inlet module for inleting flocculent sludge from a wastewater treatment plant into a one-step PN / A reactor according to a wastewater storage tank; a sludge acclimation module for acclimating the flocculent sludge in the one-step PN / A reactor into PN / A granular sludge under certain conditions; a first reaction module for performing short-cut nitrification in the one-step PN / A reactor with granular sludge and obtaining PN / A reactor effluent; a second reaction module for introducing the PN / A reactor effluent into a PD reactor and adding an organic carbon source from a carbon source tank to the PD reactor for short-cut denitrification to obtain PD reactor effluent; a deep denitrification module for introducing the PD reactor effluent into an Anammox reactor and performing deep denitrification on the PD reactor effluent according to the Anammox reactor to obtain Anammox reactor effluent; and a drainage module for discharging the Anammox reactor effluent according to an effluent storage tank.

[0013] One or more technical solutions provided in this application have at least the following beneficial effects:

[0014] This application treats wastewater treatment plant flocculent sludge sequentially by introducing it into a one-step PN / A reactor, a PD reactor, and an Anammox reactor. Through the synergistic effect of short-cut nitrification, short-cut denitrification, and anaerobic ammonium oxidation, a combined denitrification pathway with low carbon source demand, low energy consumption, and low sludge production is constructed. By setting mixed liquor sludge concentration and dissolved oxygen concentration constraints in the PN / A reactor, the formation of PN / A granular sludge is effectively promoted, improving the stability of the reaction system and denitrification efficiency. Furthermore, characteristic concentration detection and COD / NO... 3- The -N ratio adjustment enables precise control of carbon source addition in the PD reactor, significantly reducing the amount of external carbon source used. Simultaneously, the Anammox reactor incorporates a predetermined concentration ratio control and a non-woven fabric biofilm module, enhancing Anammox microbial community enrichment and reaction sustainability, ensuring effluent nitrogen concentration meets standards. Furthermore, the overall solution optimizes sludge separation and recirculation through zoned sedimentation zones, ultimately achieving the technical effects of reducing organic carbon source addition, decreasing energy consumption and excess sludge volume, and improving denitrification efficiency and process system operational stability during wastewater denitrification.

[0015] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0016] Figure 1 This is a schematic flow diagram of a combined denitrification process provided in an embodiment of this application.

[0017] Figure 2 This is a schematic diagram of the component connections of a combined denitrification process method provided in an embodiment of this application.

[0018] Figure 3 This is a morphology diagram of PN / A granular sludge in a combined denitrification process provided in an embodiment of this application.

[0019] Figure 4 This is a diagram illustrating the denitrification efficiency of a combined denitrification process method provided in this application for treating wastewater of different concentrations.

[0020] Figure 5 This is a schematic diagram of a combined denitrification process device provided in an embodiment of this application.

[0021] Explanation of reference numerals in the attached diagram: sludge inlet module 10, sludge acclimatization module 20, first reaction module 30, second reaction module 40, deep denitrification module 50, and drainage module 60. Detailed Implementation

[0022] This application addresses the technical problem that existing nitrification and denitrification processes require a large amount of external carbon source support, resulting in high energy consumption and a large amount of residual sludge. It achieves the technical effect of reducing the amount of organic carbon source added, reducing the energy consumption for wastewater denitrification, and reducing the amount of residual sludge.

[0023] Example 1, as Figure 1 As shown in the figure, this application provides a combined denitrification process method, the method comprising:

[0024] Step S1: Based on the wastewater storage tank, feed the flocculent sludge from the wastewater treatment plant into the one-step PN / A reactor.

[0025] Specifically, flocculent sludge is a flocculent substance composed of bacteria and organic particles, serving as the main microbial carrier in the biological treatment of wastewater. PN / A (Partial Nitrification-Anammox) in a one-step PN / A reactor refers to short-cut nitrification-anammox, integrating partial nitrification and Anammox processes simultaneously.

[0026] Flocculent sludge from the pretreated effluent of the wastewater treatment plant is introduced into a one-step PN / A reactor via a wastewater storage tank. The reactor can employ an SBR (Sequencing Batch Reactor) or CSTR (Completely Mixed Reactor) structure. In practice, sludge transport can be achieved using an online level control system for the wastewater storage tank and an automatic transfer pump. For example, a PLC control system can be used to link the sludge pump, precisely controlling the hourly sludge volume injected from the storage tank to ensure a stable microbial load in the reactor.

[0027] Step S1 effectively introduces microbial flocs from the activated sludge system into the PN / A system, providing a source of bacteria and organic matter for subsequent granular sludge formation and reaction initiation. At the same time, the influent volume is adjusted through the storage tank to ensure stable system operation.

[0028] Step S2: By applying conditions, the flocculent sludge in the one-step PN / A reactor is acclimated into PN / A granular sludge.

[0029] Specifically, the constraints include mixed liquor sludge concentration constraints and dissolved oxygen concentration constraints. In a one-step PN / A reactor, the reaction conditions such as mixed liquor sludge concentration and dissolved oxygen concentration are controlled to allow the sludge to circulate continuously in the reaction zone of the PN / A reactor, promoting the growth of microbial aggregation and gradually transforming the flocculent sludge into integrated PN / A granular sludge.

[0030] Furthermore, step S2 includes:

[0031] Step S21: Set the mixed liquor sludge concentration constraint, wherein the mixed liquor sludge concentration constraint is 2 to 4 g / L.

[0032] Step S22: Set the dissolved oxygen concentration constraint for the PN / A reactor, wherein the dissolved oxygen concentration constraint is 0.2 to 0.5 mg / L.

[0033] Step S23: Using the mixed liquor sludge concentration constraint and the dissolved oxygen concentration constraint as the condition constraints, control the conversion of the flocculent sludge to granular sludge in the one-step PN / A reactor.

[0034] Specifically, in a one-step PN / A reactor, an online MLSS monitor is used in conjunction with a sludge return control system to automatically adjust the sludge concentration in the reactor, controlling the mixed liquor sludge concentration during the reaction process to be 2 to 4 g / L. Excessively high sludge concentration can lead to limited oxygen transfer, while insufficient concentration can result in an inadequate reaction rate. Furthermore, the concentration can also be controlled by periodically removing sludge and adjusting the sludge retention time (SRT).

[0035] By controlling the dissolved oxygen concentration at 0.2 to 0.5 mg / L through the aeration system, the activity of ammonia nitrogen-oxidizing bacteria is effectively inhibited, promoting short-cut nitrification. The aeration system uses an online dissolved oxygen sensor to monitor the dissolved oxygen concentration in real time and adjusts the oxygen supply rate in conjunction with a variable frequency blower aerator unit or a microporous aerator system.

[0036] Combining the aforementioned sludge concentration and dissolved oxygen control mechanisms, a systematic control logic is formed. When the mixed liquor sludge concentration deviates from the target value, adjustment is made by automatic sludge discharge or reducing the sludge return ratio; when the dissolved oxygen concentration deviates from the target value, oxygen supply is regulated by reducing the air volume or switching to a low-intensity aeration zone. The entire control logic can be automated through a PLC system and a SCADA system. By comprehensively controlling sludge concentration and dissolved oxygen concentration, the conversion of flocculent sludge to granular sludge is promoted, gradually forming integrated PN / A granular sludge.

[0037] Furthermore, the sludge volume index of the PN / A granular sludge is less than 50 mL / g.

[0038] Specifically, in the actual operation of the PN / A process, to obtain an efficient and stable denitrification system, it is necessary to select PN / A granular sludge with good settling performance. Therefore, PN / A granular sludge with a sludge volume index (SVI) of less than 50 mL / g needs to be screened. In the implementation process, selective settling separators (such as sedimentators or hydraulic classification columns) can be used to retain particles with faster settling velocity in the reactor, while discharging flocculent sludge with poor flocculation. Extending the sludge settling time (SRT) and controlling the shear strength can also promote sludge granulation. Finally, the SVI measurement tool is used to determine whether the granular sludge meets the standards.

[0039] Step S2 enables the rapid enrichment of PN / A granular sludge, providing an ideal reaction substrate and microbial basis for subsequent PD and Anammox reactions.

[0040] Step S3: Short-cut nitrification is carried out using a one-step PN / A reactor with granular sludge, and effluent from the PN / A reactor is obtained.

[0041] Specifically, under the constraints of step S2, the sludge state in the one-step PN / A reactor has changed from flocculent sludge to granular sludge. At this point, the microorganisms in the sludge carry out short-cut nitrification of the wastewater, removing NH4+ from the wastewater. 4+ -N (ammonium nitrogen) is converted to NO 2- -N (nitrite nitrogen), the mixture after the reaction is the effluent from the PN / A reactor.

[0042] Step S4: Introduce the effluent from the PN / A reactor into the PD reactor, and add the organic carbon source from the carbon source box into the PD reactor for short-cut denitrification to obtain the effluent from the PD reactor.

[0043] Specifically, the effluent from the PN / A reactor is transported to the PD reactor via pipeline, while organic carbon source is added from the organic carbon source tank in a specific ratio. In the PD reactor, microorganisms utilize the organic carbon source to remove NO from the PN / A reactor effluent. 2--N (nitrite nitrogen) undergoes a short-range denitrification reaction to produce nitrogen gas and other products. The resulting mixture is the effluent from the PD reactor.

[0044] Furthermore, step S4 includes:

[0045] Step S41: Obtain the characteristic concentration of the effluent from the PN / A reactor, wherein the characteristic concentration is NO. 3- -N concentration.

[0046] Step S42: Set the influent constraint for the PD reactor, wherein the influent constraint for the PD reactor is COD / NO. 3- The -N value must be between 2.5 and 3.0.

[0047] Step S43: Using the influent constraint of the PD reactor as the control target, adjust the organic carbon source concentration of the organic carbon source box according to the characteristic concentration.

[0048] Specifically, although the PN / A reactor produces NO 2- -N is predominant, but there may still be some NH. 4+ -N is directly oxidized to NO. 3- -N, therefore, it is necessary to monitor the NO in the PN / A effluent in real time before it enters the PD reactor. 3- -N concentration. Online ion-selective electrode sensors and UV spectroscopy for NO can be used. 3- -N analyzers, etc., to achieve NO 3- -N concentration continuous monitoring and feedback.

[0049] Setting influent constraints, i.e., dynamically controlling the addition of carbon source, to control the COD / NO content of the mixed liquor entering the PD reactor. 3- The -N value should be between 2.5 and 3.0 to ensure that the short-cut denitrification reaction in the PD reactor has sufficient organic carbon source, while avoiding waste and secondary pollution caused by excessive addition of organic carbon source, thereby improving the efficiency and economy of denitrification reaction.

[0050] The detected NO 3- -N concentration is input into the carbon source control module of the carbon source storage tank and carbon source inlet pump, combined with the set COD / NO... 3- -N target ratio, automatically adjusts carbon source concentration or flow rate. For example: using sodium acetate as the carbon source, equipped with a peristaltic pump, the PLC controller adjusts the NO content based on the target ratio. 3- The -N concentration feedback signal is used to calculate and adjust the pump flow rate in real time, thereby stabilizing the effluent quality of the PD reactor.

[0051] Step S4 achieves efficient removal of nitrite and optimized utilization of carbon sources in the denitrification process while maintaining a low carbon source input, thereby reducing the consumption of organic carbon sources and reducing potential greenhouse gas emissions.

[0052] Step S5: The effluent from the PD reactor is introduced into the Anammox reactor, and the effluent from the PD reactor is subjected to deep denitrification according to the Anammox reactor to obtain Anammox reactor effluent.

[0053] Specifically, the Anammox reactor is used to achieve anaerobic ammonia oxidation, and its core microorganism is Anammox bacteria, which can convert NH4+ into nitrogen oxides. 4+ -N (ammonium nitrogen) and NO 2- -N (nitrite nitrogen) is directly converted into nitrogen gas.

[0054] The effluent from the PD reactor is piped into the Anammox reactor. In the Anammox reactor, anaerobic ammonia-oxidizing bacteria utilize the ammonia nitrogen and nitrite in the PD reactor effluent to carry out an anaerobic ammonia oxidation reaction under anaerobic conditions, converting NH3 into nitrogen. 4+ -N (ammonium nitrogen) and NO 2- -N (nitrite nitrogen) is converted into nitrogen gas, and the resulting mixture is the effluent from the Anammox reactor.

[0055] Furthermore, the feed water to the Anammox reactor meets the predetermined mass concentration ratio constraint.

[0056] Specifically, after conditioning the PD reactor, the remaining NH4+ in the influent... 4+ -N and NO 2- -N must satisfy the requirements of the Anammox reaction, NO 2- -N and NH 4+ The mass concentration ratio of NO to nitrogen (N) should be between 1 and 1.3; otherwise, incomplete reaction or bacterial inhibition may occur. The degree of denitrification in the PD reactor can be adjusted using an online ammonia / nitrite detector, a proportional flow control system, and feedback regulation from the upstream reactor to prevent NO from entering the reactor. 2- -N is excessively reduced by the carbon source. For example: if the actual NO 2- If the NO concentration is too high, the carbon source will be reduced through the control modules of the carbon source storage tank and the carbon source inlet pump to reduce NO. 3- -N to NO 2- The -N conversion restores balance.

[0057] Step S5 achieves further efficient removal of ammonia nitrogen and nitrite under anaerobic conditions, significantly reducing the total nitrogen concentration, without the need for additional carbon sources and aeration, resulting in significant overall energy saving and consumption reduction.

[0058] Step S6: Discharge the Anammox reactor effluent from the effluent storage tank.

[0059] Specifically, the effluent from the Anammox reactor is piped to an effluent storage tank, and then discharged from the storage tank according to actual needs (such as discharge standards, reuse requirements, etc.). The effluent storage tank can be equipped with a level control valve and a flow meter to control the effluent flow.

[0060] Step S6 achieves buffering and stable discharge of treated water that meets standards, improving the overall operational flexibility of the process system and the safety of the effluent quality.

[0061] Furthermore, the Anammox reactor includes an Anammox biofilm module, which is a nonwoven fabric filler with a length of 80 mm and a height of 150 mm.

[0062] Specifically, the Anammox biofilm module is used for the attachment, proliferation, and long-term stable survival of Anammox bacteria, preventing bacterial loss and increasing treatment load and reaction rate. Its dimensions of 80mm in length and 150mm in height provide ample surface area to accommodate more anaerobic ammonia-oxidizing microorganisms, thereby improving the reaction rate.

[0063] Furthermore, the one-step PN / A reactor is provided with a PN / A reaction zone and a PN / A precipitation zone.

[0064] Specifically, the PN / A reaction zone is the area within the one-step PN / A reactor where short-cut nitrification and anaerobic ammonium oxidation reactions take place. In this zone, microorganisms utilize substances such as ammonia nitrogen in wastewater to carry out short-cut nitrification under specific environmental conditions, converting NH3 into nitrogen. 4+ -N is partially oxidized to NO. 2- -N, while simultaneously undergoing anaerobic ammonium oxidation, achieves nitrogen removal.

[0065] The PN / A sedimentation zone is the sedimentation area in a one-step PN / A reactor. Its main function is to allow the sludge in the mixed liquor after the reaction to settle. Because the PN / A granular sludge formed after the microbial reaction in the PN / A reaction zone has good settling properties, the sludge can effectively settle to the bottom of the reactor in the PN / A sedimentation zone, achieving sludge-water separation, so that the supernatant (PN / A reactor effluent) can enter the next treatment stage.

[0066] Furthermore, the PD reactor is provided with a PD reaction zone and a PD precipitation zone.

[0067] Specifically, the PD reaction zone is the area within the PD reactor where short-cut denitrification occurs. In this zone, microorganisms utilize organic carbon sources to denitrify NO from the effluent of the PN / A reactor. 2- -N undergoes short-cut denitrification, reducing it to nitrogen gas, thus achieving further nitrogen removal.

[0068] The PD sedimentation zone is the sedimentation area in the PD reactor. The mixed liquid after the reaction in the PD reaction zone enters the PD sedimentation zone, where the sludge settles to the bottom of the reactor, and the supernatant (PD reactor effluent) is discharged to the next treatment stage, namely the Anammox reactor.

[0069] Figure 2 This is a schematic diagram of the component connections for a combined denitrification process provided in an embodiment of this application. The components used in this combined denitrification process include a wastewater storage tank, three influent pumps (influent pump 2, influent pump 10, and influent pump 14), an aeration pump 3, an aeration disc 4, two agitators (agitator 5 and agitator 11), a one-step PN / A reactor 6, three effluent storage tanks (effluent storage tank 7, effluent storage tank 13, and effluent storage tank 17), a carbon source storage tank 8, a carbon source inlet pump 9, a PD reactor 12, an Anammox reactor 15, and a return pump 16. The one-step PN / A reactor 6 has a PN / A reaction zone 6.1 and a PN / A sedimentation zone 6.2; the PD reactor 12 has a PD reaction zone 12.1 and a PD sedimentation zone 12.2; and the Anammox reactor 15 has an Anammox biofilm module 15.1.

[0070] The one-step PN / A reactor 6 is connected to the wastewater storage tank 1 via the inlet pump 2, and its outlet is connected to the effluent storage tank 7, and then connected to the PD reactor 12 via the inlet pump 10. The carbon source storage tank 8 is connected to the PD reactor 12 via the carbon source inlet pump 9. The outlet of the PD reactor 12 is connected to the effluent storage tank 13, and then connected to the Anammox reactor 15 via the inlet pump 14. The outlet of the Anammox reactor 16 is connected to the effluent storage tank 17.

[0071] In summary, the combined denitrification process method provided in this application has the following beneficial effects:

[0072] This application embodiment treats wastewater treatment plant flocculent sludge sequentially by introducing it into a one-step PN / A reactor, a PD reactor, and an Anammox reactor. Through the synergistic effect of short-cut nitrification, short-cut denitrification, and anaerobic ammonium oxidation, a combined denitrification pathway with low carbon source demand, low energy consumption, and low sludge production is constructed. By setting mixed liquor sludge concentration and dissolved oxygen concentration constraints in the PN / A reactor, the formation of PN / A granular sludge is effectively promoted, improving the stability of the reaction system and denitrification efficiency. Furthermore, characteristic concentration detection and COD / NO... 3-The -N ratio adjustment enables precise control of carbon source addition in the PD reactor, significantly reducing the amount of external carbon source used. Simultaneously, the Anammox reactor incorporates a predetermined concentration ratio control and a non-woven fabric biofilm module, enhancing Anammox microbial community enrichment and reaction sustainability, ensuring effluent nitrogen concentration meets standards. Furthermore, the overall solution optimizes sludge separation and recirculation through zoned sedimentation zones, ultimately achieving the technical effects of reducing organic carbon source addition, decreasing energy consumption and excess sludge volume, and improving denitrification efficiency and process system operational stability during wastewater denitrification.

[0073] Example 2: The combined denitrification process provided in this application can be used for landfill leachate. Specifically, the total nitrogen concentration of the landfill leachate is 450 mg / L to 1280 mg / L, the organic carbon source in the carbon source storage tank is sodium acetate, and the effective volumes of the one-step PN / A reactor, PD reactor, and Anammox reactor are 7.5 L, 0.9 L, and 12.6 L, respectively. The execution process is as follows:

[0074] A one-step PN / A reactor was inoculated with activated sludge from the aerobic tank of a wastewater treatment plant. The mixed liquor sludge concentration was 3.8 g / L. The dissolved oxygen concentration in the reactor was controlled below 0.5 mg / L before short-cut nitrification was started. The NO in the reactor... 2- -N accumulation rate is maintained above 95%, and NO in the effluent is reduced. 2- -N / NH 4+ After controlling the -N value to between 1.31 and 1.38, flocculent Anammox sludge was inoculated, and integrated PN / A granular sludge was cultivated. After 39 days of operation, PN / A granular sludge gradually formed (e.g., ...). Figure 3 As shown), a one-step PN / A reactor, a PD reactor, and an Anammox reactor were operated in series. The dissolved oxygen concentration in the one-step PN / A reactor was controlled at 0.2 mg / L to 0.3 mg / L, and the NH4+ concentration was... 4+ -N removal rate controlled at 93% to 95%, COD / NO in PD reactor influent 3- -N is controlled at around 2.50, NO in the PD reactor 2- -N accumulation rate remains above 80%. The effluent from the PD reactor enters the Anammox reactor for deep denitrification, and the effluent from the Anammox reactor is discharged directly.

[0075] like Figure 4 As shown, during the 211 days of operation of the combined process, the total nitrogen concentrations in the influent of the combined processes in stages II, III, and IV were 450 mg / L, 770 mg / L, and 1280 mg / L, respectively. The one-step PN / A reactor of the combined process maintained high denitrification activity, removing approximately 83% of the total nitrogen from the influent. The PD reactor only required the addition of a small amount of organic carbon source to remove NO. 3--N is converted to NO 2- -N, and NH4+ retained in the PN / A reactor 4+ -N enters the Anammox reactor for deep denitrification, NH... 4+ The removal rates of NH4+-N and total nitrogen are greater than 99% and 98%, respectively, and the concentrations of NH4+-N and TN in the effluent are less than 0.6 mg / L and 22 mg / L, respectively. Compared with traditional nitrification-denitrification processes, it saves approximately 60% of aeration energy consumption and 93% of organic carbon source.

[0076] Example 3, as Figure 5 As shown, based on the same inventive concept as in Embodiment 1 above, this application provides a combined denitrification process apparatus, the apparatus comprising:

[0077] The sludge inlet module 10 is used to inlet the flocculent sludge from the wastewater treatment plant into the one-step PN / A reactor according to the wastewater storage tank.

[0078] The sludge acclimation module 20 is used to acclimate the flocculent sludge in the one-step PN / A reactor into PN / A granular sludge by means of conditional constraints.

[0079] The first reaction module 30 is used to carry out short-cut nitrification reaction in a one-step PN / A reactor with sludge in granular sludge state, and to obtain PN / A reactor effluent.

[0080] The second reaction module 40 is used to introduce the effluent from the PN / A reactor into the PD reactor, and to add an organic carbon source from the carbon source box into the PD reactor for short-cut denitrification to obtain the effluent from the PD reactor.

[0081] The deep denitrification module 50 is used to introduce the effluent from the PD reactor into the Anammox reactor, and to perform deep denitrification on the effluent from the PD reactor according to the Anammox reactor to obtain the effluent from the Anammox reactor.

[0082] The drainage module 60 is used to discharge the effluent from the Anammox reactor according to the effluent storage tank.

[0083] Furthermore, in this embodiment of the application, the first reaction module 30 is also used to perform the following steps:

[0084] A mixed liquor sludge concentration constraint is set, which is 2 to 4 g / L; a dissolved oxygen concentration constraint is set for the PN / A reactor, which is 0.2 to 0.5 mg / L; the mixed liquor sludge concentration constraint and the dissolved oxygen concentration constraint are used as the condition constraints to control the conversion of flocculent sludge to granular sludge in the one-step PN / A reactor.

[0085] Furthermore, the sludge volume index of the PN / A granular sludge is less than 50 mL / g.

[0086] Furthermore, in this embodiment of the application, the second reaction module 40 is also used to perform the following steps:

[0087] The characteristic concentration of the effluent from the PN / A reactor is obtained, wherein the characteristic concentration is NO. 3- -N concentration; setting influent constraints for the PD reactor, wherein the influent constraints for the PD reactor are COD / NO. 3- -N value satisfies 2.5 to 3.0; with the influent constraint of the PD reactor as the control target, the organic carbon source concentration of the organic carbon source box is adjusted according to the characteristic concentration.

[0088] Furthermore, the feed water to the Anammox reactor meets the predetermined mass concentration ratio constraint.

[0089] Furthermore, the Anammox reactor includes an Anammox biofilm module, which is a nonwoven fabric filler with a length of 80 mm and a height of 150 mm.

[0090] Furthermore, the one-step PN / A reactor is provided with a PN / A reaction zone and a PN / A precipitation zone.

[0091] Furthermore, the PD reactor is provided with a PD reaction zone and a PD precipitation zone.

[0092] Through the detailed description of a combined denitrification process method in the foregoing Embodiment 1, those skilled in the art can clearly understand that the combined denitrification process device in this embodiment corresponds to the device disclosed in Embodiment 3. Since it is in line with the method disclosed in Embodiment 1, it has corresponding functional modules and beneficial effects. For relevant details, please refer to the method section.

[0093] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A combined denitrification process method, characterized in that, The method includes: Based on the wastewater storage tank, the flocculent sludge from the wastewater treatment plant is fed into a one-step PN / A reactor; By applying certain conditions, the flocculent sludge in the one-step PN / A reactor is acclimated into PN / A granular sludge. A one-step PN / A reactor with granular sludge was used to carry out short-cut nitrification and obtain PN / A reactor effluent. The effluent from the PN / A reactor is introduced into the PD reactor, and an organic carbon source is added from the carbon source box to the PD reactor for short-cut denitrification to obtain the effluent from the PD reactor. The effluent from the PD reactor is introduced into the Anammox reactor, and the Anammox reactor is used to perform deep denitrification on the effluent from the PD reactor to obtain Anammox reactor effluent. The Anammox reactor effluent is discharged from the effluent storage tank; The effluent from the PN / A reactor is introduced into the PD reactor, and an organic carbon source is added from the carbon source tank to the PD reactor for short-cut denitrification to obtain the PD reactor effluent, including: The characteristic concentration of the effluent from the PN / A reactor is obtained, wherein the characteristic concentration is NO. 3- -N concentration; A PD reactor influent constraint is set, wherein the PD reactor influent constraint is COD / NO. 3- -N values ​​must be between 2.5 and 3.0; Using the influent constraint of the PD reactor as the control target, the concentration of organic carbon source in the carbon source tank is adjusted according to the characteristic concentration; The Anammox reactor influent meets a predetermined mass concentration ratio constraint, with the influent constraint being NO. 2- -N and NH 4+ The mass concentration ratio of -N is 1 to 1.

3. The concentration of organic carbon source in the carbon source box is adjusted with the influent constraint of the Anammox reactor as the control target.

2. The combined denitrification process method as described in claim 1, characterized in that, By applying certain conditions, the flocculent sludge in the one-step PN / A reactor is acclimated into PN / A granular sludge, including: A mixed liquor sludge concentration constraint is set, wherein the mixed liquor sludge concentration constraint is 2 to 4 g / L; The dissolved oxygen concentration is constrained for the PN / A reactor, which is 0.2 to 0.5 mg / L. The conversion of flocculent sludge to granular sludge in the one-step PN / A reactor is controlled by the constraints of the mixed liquor sludge concentration and the dissolved oxygen concentration.

3. The combined denitrification process method as described in claim 1, characterized in that, The sludge volume index of the PN / A granular sludge is less than 50 mL / g.

4. The combined denitrification process method as described in claim 1, characterized in that, The Anammox reactor includes an Anammox biofilm module, which is a non-woven fabric filler with a length of 80 mm and a height of 150 mm.

5. The combined denitrification process method as described in claim 1, characterized in that, The one-step PN / A reactor is provided with a PN / A reaction zone and a PN / A precipitation zone.

6. The combined denitrification process method as described in claim 1, characterized in that, The PD reactor is equipped with a PD reaction zone and a PD precipitation zone.

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