A rapid detection method for performance evaluation of denitrification and phosphorus removal biological system

Abstract

The present application belongs to the technical field of sewage treatment, and relates to a rapid detection method for performance evaluation of a denitrification and phosphorus removal biological system, which comprises the following steps: sludge biological denitrification and phosphorus removal rate test, biological system whole-process test and test data analysis; the denitrification and phosphorus removal test method can master the optimal potential of microbial denitrification and phosphorus removal in a short time; the biological system whole-process test is refined to each functional unit, core control indexes of each functional unit are proposed, and sampling points are optimized, which not only reduces the number of samples for sampling and testing and shortens the overall test time, but also solves the actual problem of missing functional unit data; test data are combined with process operation parameter analysis to calculate the theoretical conversion amount and actual removal amount of pollutants in the functional unit, and the potential for improving denitrification and phosphorus removal is compared and judged; the test method constructed by the present application is step-by-step, short in test time, and provides support for obtaining basic data for performance evaluation of the denitrification and phosphorus removal biological system.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a rapid detection method for performance evaluation of biological systems for nitrogen and phosphorus removal. Background Technology

[0002] The focus of urban wastewater treatment in my country has shifted from pollutant reduction to water reuse and the replenishment of aquatic ecosystems. With the successive implementation of high discharge standards in Beijing, Tianjin, Taihu Lake, Dianchi Lake, and other regions, using wastewater from treatment plants as reclaimed water to supplement water bodies has become a crucial way to conserve water resources, placing more stringent demands on the enhanced removal of nitrogen and phosphorus nutrients from wastewater. Currently, designers commonly employ process methods such as adjusting the size, arrangement, and number of anaerobic, anoxic, and aerobic functional zones, as well as changing the mixed liquor circulation and recirculation methods, to ensure that effluent consistently meets high discharge standards.

[0003] High emission standards and the simultaneous operation of multiple functional units place increasingly higher demands on the operational technology of wastewater treatment plants. However, many wastewater treatment plants still rely on the addition of large amounts of chemical reagents to ensure stable effluent compliance. Achieving pollutant reduction and emission control at the expense of high energy and chemical consumption fails to fully realize the operational potential of each process unit in the biological system, hindering the realization of green, low-carbon, and intensive operation of wastewater treatment plants. Under the new circumstances of low-carbon development, it is necessary to further reduce energy and material consumption while ensuring the stable operation of all treatment systems in wastewater treatment plants, thereby achieving sustainable development.

[0004] A comprehensive and accurate understanding of the operational status of each process unit is fundamental and crucial for quickly resolving the aforementioned issues. However, most wastewater treatment plants currently only provide routine influent and effluent water quality indicators and daily inspection records. Testing the operational status of biological system process units is not within the scope of routine operation management, failing to effectively accumulate relevant data for performance evaluation of nitrogen and phosphorus removal biological systems, thus hindering the development of refined operation management plans. Therefore, it is necessary to establish a standardized rapid testing method for performance evaluation of nitrogen and phosphorus removal biological systems to complete the testing of core control parameters required for evaluation, providing data support for operational efficiency diagnosis and energy conservation and consumption reduction. Summary of the Invention

[0005] The purpose of this invention is to provide a rapid detection method for evaluating the performance of biological nitrogen and phosphorus removal systems, which can solve the problems of difficulty in evaluating the nitrogen and phosphorus removal performance of biological systems and difficulty in determining operational optimization due to insufficient knowledge of core control parameters during the operation of wastewater treatment plants.

[0006] To achieve the above technical objectives, the technical solution adopted by this invention is: a rapid detection method for performance evaluation of a nitrogen and phosphorus removal biological system, comprising the following steps:

[0007] Step S1. Sludge microbial denitrification and phosphorus removal rate test: Add a fast carbon source to the pretreated return sludge to simulate anaerobic, anoxic and aerobic environments, and calculate the denitrification and phosphorus removal rate of different functional sections.

[0008] Step S2. Full-process testing of biological systems: Determine the test process units and sampling points based on the process design, determine the core test indicators based on the function of the process units, and sample and test throughout the entire process;

[0009] Step S3. Test Data Analysis: Based on steps S1 and S2, and combined with the actual influent water quality, water quantity, and process operating parameters, calculate the theoretical conversion and actual removal of pollutants in the functional units. Through data comparison, evaluate whether the biological system has fully realized its phosphorus and nitrogen removal potential. If there is potential for improvement, formulate a process optimization plan for the phosphorus and nitrogen removal biological system based on the measured actual environmental parameters and sludge performance parameters.

[0010] Furthermore, the sludge microbial denitrification and phosphorus removal rate test in step S1 includes the following steps:

[0011] (1) Pretreatment of return sludge: Take 3-5L of return sludge and deoxygenate it to DO<0.2mg / L. As P, add 10-15mg of potassium dihydrogen phosphate (KH2PO4) to the sludge. After sludge-water separation, test the phosphate (PO4) content of the supernatant. 3－ -P concentration, stir for 5-10 minutes, and test again to determine PO4 concentration. 3－ -P concentration remains constant to eliminate interference from residual phosphorus removal agents;

[0012] (2) Add sufficient rapid carbon source to the pretreated return sludge and stir. Take the mixture at different time points, separate the sludge and water, and test the PO4 in the supernatant. 3－ -P concentration, after a duration of not less than 30 minutes, calculate the nitrate NO3-N concentration standard in the supernatant, and add 5-10 mg / L potassium nitrate (KNO3) as N; take the mixture at different time points, separate the mud and water, and test the NO3-N concentration in the supernatant. After a reaction time of not less than 1 hour, combine with the remaining PO4. 3- To adjust the concentrations of -P and NO3-N, add appropriate amounts of KH2PO4 and ammonium chloride (NH4Cl) to ensure the concentration of PO4 in the supernatant. 3- -P concentration not less than 5 mg / L, NH4 + Aeration is initiated when the NH4+ concentration is not less than 10 mg / L. When the DO concentration exceeds 2 mg / L, samples of the mixed liquor are taken at different time points. After sludge-water separation, the NH4+ concentration in the supernatant is tested. + -N, the experiment ended after the duration was greater than 1 hour, and the concentration of volatile matter in the mixed liquor (MLVSS) was measured.

[0013] (3) Draw PO4 respectively 3－-P~t, NO3-N~t, NH4 + -N~t linear relationship diagram, and combined with MLVSS to calculate the phosphorus release rate of activated sludge in the anaerobic section, the denitrification and phosphorus removal rate in the anoxic section, and the nitrification and phosphorus uptake rate in the aerobic section.

[0014] Furthermore, the amount of rapid carbon source added in step (2) ensures that the initial COD in the mixture is not less than 60 mg / L, and the mixture is stirred at a low speed of 50-100 rpm.

[0015] Furthermore, the test process units for the full-process biological system test described in step S2 include a pre-anoxic section, an anaerobic section, a denitrification and phosphorus removal section, a first anoxic section, a first aerobic section, an oxygen-removing section, a second anoxic section, a second aerobic section, and a secondary sedimentation tank. The mixed liquor is recirculated from the outlet of the first aerobic section to the inlet of the first anoxic section and from the outlet of the second aerobic section to the inlet of the second anoxic section. The sludge is recirculated from the outlet of the secondary sedimentation tank into the inlet of the pre-anoxic section. The above functional units can be flexibly adjusted according to the actual process. The specific process units and the mixed liquor and sludge recirculation modes should be clearly defined before the test.

[0016] Furthermore, the test sampling points determined in step S2 based on the functional unit settings and operating modes include: the front and end of the pre-anoxic section; the end of the anaerobic section; the end of the denitrification and phosphorus removal section; the end of the first anoxic section; the front, middle, and end of the first aerobic section; the end of the deoxygenation section; the end of the second anoxic section; the front, middle, and end of the second aerobic section; the effluent weir of the secondary sedimentation tank; the front of the mixed liquor entering the anoxic section; and the front of the sludge return flow into and out of the anaerobic section.

[0017] Furthermore, the core test indicators mentioned in step S2 include environmental parameters, water quality parameters, and sludge performance parameters.

[0018] Furthermore, the environmental parameters include DO and ORP at the front end of the pre-anoxic zone; ORP in the anaerobic zone; ORP in the denitrification and phosphorus removal zone; ORP and pH in the first anoxic zone; DO, ORP, and pH at the front, middle, and end of the first aerobic zone; DO and ORP at the end of the deoxygenation zone; DO and ORP at the end of the second anoxic zone; DO, ORP, and pH at the front, middle, and end of the second aerobic zone; DO and ORP in the secondary sedimentation tank; DO at the inlet of the mixed liquor recirculation into the anoxic tank; and DO at the inlet of the sludge recirculation zone into the anaerobic tank. All of the above environmental parameters need to be tested on-site at the functional unit.

[0019] Furthermore, the water quality parameters include NO3-N and PO4 in the supernatant of activated sludge at the end of the pre-anoxic stage. 3- -P; Ammonia nitrogen (NO3-N), PO4- in the supernatant of activated sludge at the end of the anaerobic stage 3- -P; PO4 in the supernatant of activated sludge at the end of the denitrification and phosphorus removal stage.3- -P and NO3-N; dissolved organic matter (SCOD), NO3-N, and PO4 in the supernatant of activated sludge at the end of the first anoxic stage. 3- -P; NH4+ in the supernatant of activated sludge at the beginning, middle, and end of the first aerobic stage. + -N, NO3-N, PO4 3- -P; SCOD and PO4 in the supernatant of activated sludge at the end of the second anoxic stage 3- -P and NO3-N; NH4+ in the supernatant of activated sludge from the front, middle, and rear sections of the second aerobic stage. + -N, NO3-N, PO4 3- -P; NO3-N and PO4- in the effluent from the secondary sedimentation tank weir 3- -P; NO3-N and PO4- in the supernatant of activated sludge at the inlet of the mixed liquor return zone into the anoxic tank. 3- -P; The sludge return zone enters the anaerobic tank through the inlet of activated sludge containing NO3-N and PO4-. 3- -P, the supernatant of activated sludge from each functional unit needs to be sampled on-site and then quickly separated into sludge and water to prevent the microorganisms in the sludge from continuing to react and causing deviations in the results.

[0020] Furthermore, the sludge performance parameters include the color, water temperature, and sludge settling ratio (SV) of the activated sludge at the end of the first and second aerobic stages. 30 MLSS concentration of sludge, MLVSS concentration of sludge volatile matter, and phosphorus content of sludge.

[0021] Furthermore, the test data analysis described in step S3 specifically includes the following steps:

[0022] By testing the potential of biological nitrogen and phosphorus removal in sludge, the pollutant conversion rate corresponding to the functional unit of the biological system was obtained. Combined with the parameters of the unit, including influent water quality and quantity, sludge concentration, and hydraulic retention time, the theoretical conversion amount of pollutants by the functional unit was calculated.

[0023] By testing the current status of the biological system and combining it with material balance, the actual amount of pollutants removed by this functional unit was calculated.

[0024] When the theoretical conversion amount of pollutants minus the actual removal amount is ≥3 mg / L, a process optimization plan is formulated for the nitrogen and phosphorus removal biological system by referring to the measured actual environmental parameters and sludge performance parameters.

[0025] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows:

[0026] 1. This invention adds a rapid carbon source during sludge biological rate testing, which can accelerate the reaction rate of microbial nitrogen and phosphorus removal and allow for the determination of the optimal potential of microbial nitrogen and phosphorus removal in a short time. It simulates different operating environments in the same reactor and clarifies the range of sampling, dosage, and testing time. The procedure is standardized, and the test materials and added agents are readily available. It is applicable to most wastewater treatment plants and can be promoted and replicated.

[0027] 2. The biological system full-process testing and detection method provided by this invention refines the testing steps to each functional unit and proposes the core control indicators for each functional unit, which can solve the technical problem of scientifically selecting monitoring indicators for wastewater treatment functional areas under the interaction of process units.

[0028] 3. During the testing process, sampling is combined with the sequential characteristics of functional units. The exit of a certain functional unit is the entry of the next functional unit, and the stop time of a certain function is the start time of the next function. By making full use of the temporal or spatial continuity of functional units, the number of samples for testing is reduced, and the operational status can be grasped in a short time, making up for the actual problem of missing data of functional units.

[0029] 4. By combining test data with process operation parameters, the theoretical conversion and actual removal of pollutants in functional units are calculated, and the potential for improvement in phosphorus and nitrogen removal is compared and judged, providing support for obtaining basic data for the performance evaluation of the nitrogen and phosphorus removal biological system.

[0030] 5. The nitrogen and phosphorus removal testing method of this invention can quickly determine the optimal potential of microbial nitrogen and phosphorus removal; the whole-process testing of the biological system is refined to each functional unit, proposing the core control indicators of each functional unit and optimizing the sampling points, which not only reduces the number of samples for testing and shortens the overall testing time, but also makes up for the actual problem of missing data for functional units; the test data is combined with the analysis of process operation parameters to calculate the theoretical conversion amount and actual removal amount of pollutants in the functional units, and compare and judge the potential for improvement in phosphorus and nitrogen removal; the testing method constructed by this invention has standardized steps and short testing time, providing support for obtaining basic data for the performance evaluation of nitrogen and phosphorus removal biological systems. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the functional unit partitioning of the wastewater treatment plant operation efficiency evaluation system of the present invention.

[0032] Figure 2 This is a flowchart illustrating the functional zoning and water circulation method of the biological system in an embodiment of the present invention.

[0033] Figure 3 This is a graph showing the test results of the nitrogen and phosphorus removal rate of sludge in an embodiment of the present invention. Detailed Implementation

[0034] A rapid detection method for performance evaluation of a nitrogen and phosphorus removal biological system includes the following steps:

[0035] Step S1. Sludge microbial denitrification and phosphorus removal rate test: Add a fast carbon source to the pretreated return sludge to simulate anaerobic, anoxic, and aerobic environments, and calculate the denitrification and phosphorus removal rates of different functional sections.

[0036] Specifically, the sludge microbial denitrification and phosphorus removal rate test in step S1 includes the following steps:

[0037] (1) Pretreatment of returned sludge: Take 3-5L of returned sludge and deoxygenate it to DO < 0.2mg / L. Add 10-15mg (as P) of potassium dihydrogen phosphate (KH2PO4). After sludge-water separation, test the phosphate (PO4) content of the supernatant. 3－ -P) concentration, stir for 5-10 minutes, and test again to determine PO4 concentration. 3－ -P concentration remains constant to eliminate interference from residual phosphorus removal agents;

[0038] (2) Add sufficient rapid carbon source to the pretreated return sludge to ensure that the initial COD in the mixed liquor is not less than 60 mg / L, and stir at a low speed of 50-100 rpm. Take the mixed liquor at different time points, and test the PO4 in the supernatant after sludge-water separation. 3－ After maintaining the -P concentration for at least 30 minutes, add 5-10 mg / L (as N) of potassium nitrate (KNO3) to the supernatant based on the standard nitrate (NO3-N) concentration. Take samples of the mixture at different time points, separate the mud and water, and test the NO3 concentration in the supernatant. － -N concentration, reaction time not less than 1 hour, combined with remaining PO4 3- To adjust the concentrations of -P and NO3-N, add appropriate amounts of KH2PO4 and ammonium chloride (NH4Cl) to ensure the supernatant contains PO4. 3- -P not less than 5 mg / L, NH4 + Aeration is initiated when NH4+ concentration is not less than 10 mg / L. When DO concentration exceeds 2 mg / L, samples of the mixed liquor are taken at different time points. After sludge-water separation, the NH4+ concentration in the supernatant is tested. + -N, the experiment ended after the duration was greater than 1 hour, and the concentration of volatile sludge in the mixed liquor (MLVSS) was measured;

[0039] (3) Draw PO4 respectively 3－ -P~t, NO3-N~t, NH4 + -N~t linear relationship diagram, and combined with MLVSS to calculate the phosphorus release rate in the anaerobic zone, the denitrification and phosphorus removal rate in the anoxic zone, and the nitrification and phosphorus uptake rate in the aerobic zone of activated sludge.

[0040] Step S2. Full-process testing of biological systems: Determine the test process units and sampling points based on the process design, determine the core test indicators based on the function of the process units, and sample and test throughout the entire process.

[0041] like Figure 1 As shown, the test process units for the full-process biological system test include, in sequence, a pre-anoxic section, an anaerobic section, a denitrification and phosphorus removal section, a first anoxic section, a first aerobic section, an oxygen-depleting section, a second anoxic section, a second aerobic section, and a secondary sedimentation tank. The mixed liquor flows back from the outlet of the first aerobic section to the inlet of the first anoxic section, and from the outlet of the second aerobic section to the inlet of the second anoxic section. The sludge flows back from the outlet of the secondary sedimentation tank to the inlet of the pre-anoxic section. The above functional units can be flexibly adjusted according to the actual process. Before the test, the specific process units and the mixed liquor and sludge return modes need to be clearly defined.

[0042] The test sampling points determined based on the functional unit settings and operating modes include: the front and rear ends of the pre-anoxic section; the end of the anaerobic section; the end of the denitrification and phosphorus removal section; the end of the first anoxic section; the front, middle, and rear ends of the first aerobic section; the end of the deoxygenation section; the end of the second anoxic section; the front, middle, and rear ends of the second aerobic section; the effluent weir of the secondary sedimentation tank; and the front ends of the mixed liquor entering the first and second anoxic sections.

[0043] The core testing indicators include environmental parameters, water quality parameters, and sludge performance parameters.

[0044] The environmental parameters include DO and ORP at the front end of the pre-anoxic zone; ORP in the anaerobic zone; ORP in the denitrification and phosphorus removal zone; ORP and pH in the first anoxic zone; DO, ORP, and pH at the front, middle, and end of the first aerobic zone; DO and ORP at the end of the deoxygenation zone; DO and ORP at the end of the second anoxic zone; DO, ORP, and pH at the front, middle, and end of the second aerobic zone; DO and ORP in the secondary sedimentation tank; DO at the inlet of the mixed liquor return to the anoxic tank; and DO at the inlet of the sludge return zone to the anaerobic tank. All of the above environmental parameters need to be tested on-site at the functional unit.

[0045] Water quality parameters include NO3-N and PO4 in the supernatant of activated sludge at the end of the pre-anoxic stage. 3- -P; Ammonia nitrogen (NO3-N), PO4- in the supernatant of activated sludge at the end of the anaerobic stage 3- -P; PO4 in the supernatant of activated sludge at the end of the denitrification and phosphorus removal stage. 3- -P and NO3-N; dissolved organic matter (SCOD), NO3-N, and PO4 in the supernatant of activated sludge at the end of the first anoxic stage. 3- -P; NH4+ in the supernatant of activated sludge at the beginning, middle, and end of the first aerobic stage. + -N, NO3-N, PO43- -P; SCOD and PO4 in the supernatant of activated sludge at the end of the second anoxic stage 3- -P and NO3-N; NH4+ in the supernatant of activated sludge from the front, middle, and rear of the second aerobic stage. + -N, NO3-N, PO4 3- -P; NO3-N and PO4- in the effluent from the secondary sedimentation tank weir 3- -P; NO3-N and PO4- in the supernatant of activated sludge at the inlet of the mixed liquor return zone into the anoxic tank. 3- -P; The sludge return zone enters the anaerobic tank through the inlet of activated sludge containing NO3-N and PO4-. 3- -P, the supernatant of activated sludge from each functional unit needs to be sampled on-site and then quickly separated into sludge and water to prevent the microorganisms in the sludge from continuing to react and causing deviations in the results.

[0046] Sludge performance parameters include the color, water temperature, and sludge settling ratio (SV) of the activated sludge at the end of the first and second aerobic stages. 30 MLSS concentration of sludge, MLVSS concentration of sludge volatile matter, and phosphorus content of sludge.

[0047] Step S3. Test Data Analysis: Based on steps S1 and S2, and combined with process operating parameters, calculate the theoretical conversion and actual removal of pollutants in the functional units. Through data comparison, evaluate whether the biological system has fully realized its phosphorus and nitrogen removal potential. If there is potential for improvement, a process optimization plan should be formulated for the phosphorus and nitrogen removal biological system, taking into account the measured actual environmental parameters and sludge performance parameters.

[0048] Specifically, test data analysis includes the following steps:

[0049] By testing the potential of biological nitrogen and phosphorus removal in sludge, the theoretical conversion rate of pollutants corresponding to the functional unit of the biological system was obtained. Combined with the parameters of the unit, including influent water quality and quantity, sludge concentration, and hydraulic retention time, the theoretical conversion amount of pollutants by the functional unit was calculated.

[0050] By testing the current status of the biological system and combining it with material balance, the actual amount of pollutants removed by this functional unit was calculated.

[0051] By comparing the theoretical conversion amount with the actual removal amount, when the theoretical conversion amount minus the actual removal amount of pollutants is ≥3mg / L, a process optimization plan is formulated for the nitrogen and phosphorus removal biological system with reference to the measured actual environmental parameters and sludge performance parameters.

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0053] Example 1

[0054] The biological treatment process used in the wastewater treatment plant is an aerated grit chamber + A+A process. 2 / O+High-efficiency sedimentation tank + deep bed filter, designed treatment capacity of 5×10 4 m 3 The designed effluent quality complies with the Class A standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002) and the requirements of the "Environmental Quality Standard for Surface Water" (Class IV). The total hydraulic retention time (HRT) of the biological treatment area is designed to be 20.5 h, including a pre-anoxic zone of 0.5 h, an anaerobic zone of 1.2 h, anoxic zone of 8.3 h, and aerobic zone of 10.5 h. The sludge retention time (SRT) is 16 days.

[0055] The sludge is returned from the secondary sedimentation tank to the pre-anoxic zone with a return ratio of 100%. The mixed liquor is returned from the aerobic zone to the anoxic zone with a return ratio of 100%. The designed average sludge concentration (MLSS) of the mixed liquor is 4500 mg / L.

[0056] A rapid testing method for evaluating the nitrogen and phosphorus removal performance of the biological system in the aforementioned wastewater treatment plant includes the following steps:

[0057] Step S1. Sludge microbial denitrification and phosphorus removal rate test: Add a fast carbon source to the pretreated return sludge to simulate anaerobic, anoxic and aerobic environments, and calculate the denitrification and phosphorus removal rate of different functional sections.

[0058] Specifically, 5L of return sludge was deoxygenated to DO < 0.2mg / L, 10mg of KH2PO4 was added, and the PO4 content of the supernatant was tested. 3- -P was 2.3 mg / L. After stirring for 5 minutes, PO4 was tested. 3- -P was 1.0 mg / L. After stirring for another 5 minutes, PO4 was tested again. 3- -P was 0.98 mg / L, and PO4 was measured twice. 3－ -P concentration remained almost unchanged, indicating that interference from remaining phosphorus removal agents had been eliminated;

[0059] Add sufficient rapid carbon source to the pretreated return sludge to ensure that the initial COD in the mixed liquor is not less than 60 mg / L, and stir at a low speed of 50-100 rpm. Take the mixed liquor at different time points, and after sludge-water separation, test the PO4 in the supernatant. 3- -P concentration, after 30 min, nitrate (NO) in the supernatant 3- NO3-N concentration standard calculation: 10 mg / L (as N) KNO3 was added, and the mixture was taken at different time points. After mud-water separation, the NO3-N concentration in the supernatant was tested. After 1 hour of reaction, the remaining PO4- was combined.3- -P and NO3-N concentrations were determined by adding appropriate amounts of KH2PO4 and NH4Cl, and the PO4 content of the supernatant was tested. 3- -P is 5.3 mg / L, NH4 + Aeration was initiated with N at 12.5 mg / L. When DO > 2 mg / L, samples were taken from the mixed liquor at different time points. After sludge-water separation, the NH4+ in the supernatant was tested. + -N, the experiment ended after 1.5 hours, and the MLVSS in the mixture was tested;

[0060] Draw PO4 separately 3- -P and t, NO 3- -N and t, NH4 + The linear relationship between -N and t was plotted, and the phosphorus release rate in the anaerobic stage, the denitrification rate in the anoxic stage, and the nitrification rate in the aerobic stage of the activated sludge were calculated using MLVSS. The test data for each stage are shown in Table 1 below:

[0061] Table 1 Test data at different stages

[0062]

[0063] Based on the data in the table, plot the graphs in stages, see... Figure 3 As shown, the concentration exhibits a linear relationship with time. Based on this linear relationship, the slope was calculated. Combined with the MLVSS concentration of the returned sludge (4100 mg / L), the phosphorus release rate in the anaerobic zone per unit time can be calculated to be 4.2 mg PO4. 3- The denitrification rate was -P / (gVSS·h), and the nitrogen removal rate was 1.01 mg NO3-N / (gVSS·h). The nitrification rate in the aerobic stage was 2.01 mg NH4. + -N / (gVSS·h);

[0064] Step S2. Full-process testing of biological systems: Determine the test process units and sampling points based on the process design, determine the core test indicators based on the function of the process units, and sample and test throughout the entire process;

[0065] The test process units for the full-process biological system test include a pre-anoxic section, an anaerobic section, anoxic section, aerobic section, secondary sedimentation tank, and advanced treatment unit arranged in sequence. The mixed liquor is returned from the outlet of the secondary sedimentation tank to the inlet of the pre-anoxic tank with a sludge return ratio of 100%. The mixed liquor is returned from the outlet of the aerobic section to the inlet of the anoxic section with a return ratio of 100%.

[0066] The test sampling points include: the front and end of the pre-anoxic section; the end of the anaerobic section, the end of the anoxic section, the front, middle and end of the aerobic section, the mixed liquor return inlet, the sludge return inlet and the secondary sedimentation tank effluent weir.

[0067] Based on the water circulation mode of the biological system in the wastewater treatment plant, the environmental parameters and water quality parameters tested at the functional unit sampling points are shown in Table 2.

[0068]

[0069] Step S3. Test Data Analysis: Based on the sludge denitrification and phosphorus removal rate test results in Step S1 and the full-process biological system detection results in Step S2, combined with the influent water quality and quantity and process operating parameters, the theoretical conversion and actual removal amounts of pollutants in the functional units are calculated, as shown in Table 3.

[0070] Table 3. Calculation of Theoretical Conversion Amount and Actual Removal Amount

[0071]

[0072] As can be seen from the table, the actual pollutant removal amount of each functional unit of the biological system (the full-process detection results of the biological system in step S2, see Table 2) and the theoretical conversion amount (the sludge denitrification and phosphorus removal rate test results in step S1, see Table 1 and Table 2) are significantly different. Figure 3 The difference is large. Except for the pre-anoxic state, the theoretical conversion amount of pollutants in the other functional units is higher than 3 mg / L compared with the actual removal amount. This indicates that the nitrogen and phosphorus removal performance of the biological system has not been fully utilized. It is necessary to formulate a process optimization plan based on the measured environmental parameters and sludge performance parameters.

[0073] The present invention provides a rapid testing method for evaluating the performance of biological nitrogen and phosphorus removal systems. The sludge biological rate testing method involves adding a rapid carbon source to accelerate the reaction rate of microbial nitrogen and phosphorus removal, allowing for the determination of the optimal potential of microbial nitrogen and phosphorus removal in a short time. The method simulates different operating environments in the same reactor, while clearly defining the range of sampling, dosage, and testing time. The steps are standardized, and the test materials and added agents are readily available. It is applicable to most wastewater treatment plants and can be promoted and replicated.

[0074] Current technologies select conservative nitrogen and phosphorus removal reaction rates based on actual operational measurements at wastewater treatment plants. However, in actual operation of biological system functional units, the actual residence times vary between anoxic, anaerobic, and aerobic units, sometimes exceeding 10 hours. When measuring rates, the influent and effluent sampling time intervals must match the actual residence times, and the MLVSS concentration in the sludge of each functional unit must be measured individually to obtain the reaction rate for that unit. Furthermore, actual influent contains both fast and slow carbon sources, making it difficult to accurately determine the optimal performance of microbial nitrogen and phosphorus removal, thus complicating the evaluation of biological nitrogen and phosphorus removal performance.

[0075] Comparative Example 1

[0076] Taking the determination of nitrification rate in an aerobic tank as an example, the "Outdoor Drainage Design Standard" (GB50014-2021) proposes that among the main design parameters for biological nitrogen and phosphorus removal using anaerobic / anoxic / aerobic methods, the HRT of the aerobic section is 7-11 hours. The test method for the nitrification rate of the aerobic tank is as follows: take the influent from the front end of the aerobic tank and measure the NH4+ in the supernatant. + -N, after 7-11 hours, take the NH4+ from the effluent at the end of the aerobic tank and measure the NH4+ in the supernatant. + -N, and test the MLVSS of activated sludge in the tank, and calculate the nitrification rate in combination with HRT.

[0077] Currently, most wastewater treatment plants only provide influent flow rate, routine testing records for influent and effluent quality indicators such as COD, TN, and TP, and daily inspection records. Testing the operational status of biological system process units is not included in routine operation and management. To maintain stable effluent compliance, wastewater treatment plants typically add chemical agents to the biological system and install additional operating equipment to achieve nitrogen and phosphorus removal. However, the actual functions of the microorganisms in the existing process units are not fully utilized, hindering the realization of green and low-carbon operation of wastewater treatment plants. Existing performance testing methods for nitrogen and phosphorus removal biological systems suffer from a lack of data for each functional unit. They can only combine the actual hydraulic retention time and MLVSS of each functional unit to measure the reaction rate, resulting in lengthy testing processes and large sample sizes.

[0078] The rapid detection method provided by this invention can simulate different operating environments in the same reactor without changing the MLVSS concentration. It also clarifies the range of sampling, dosage, and testing time, with standardized procedures. The test materials and added reagents are readily available and applicable to most wastewater treatment plants. It can quickly determine the potential of microorganisms for nitrogen and phosphorus removal, and complete the testing of core control parameters of each functional unit of the biological system in a short time. This provides support for the acquisition of basic data required for the performance evaluation of nitrogen and phosphorus removal biological systems and the formulation of energy-saving and consumption-reducing process optimization schemes.

[0079] The sludge biorate testing method provided in this embodiment of the invention adds a rapid carbon source to accelerate the microbial nitrogen and phosphorus removal reaction rate, allowing for the rapid determination of the optimal potential for microbial nitrogen and phosphorus removal. The method simulates different operating environments in the same reactor, clearly defining the ranges for sampling, dosage, and testing time. The steps are standardized, and the experimental materials and added reagents are readily available, making it applicable to most wastewater treatment plants and easily replicable. In contrast, the method in the comparative example requires a much longer time.

[0080] The specific embodiments described above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements or substitutions without departing from the principle of the present invention, and these improvements or substitutions should be considered within the scope of protection of the present invention.

Claims

1. A rapid detection method for performance evaluation of a nitrogen and phosphorus removal biological system, characterized in that, Includes the following steps: Step S1. Sludge microbial denitrification and phosphorus removal rate test: Add a fast carbon source to the pretreated return sludge to simulate anaerobic, anoxic and aerobic environments, and calculate the denitrification and phosphorus removal rate of different functional sections. Step S2. Full-process testing of biological systems: Determine the test functional units and sampling points based on the process design, determine the core test indicators based on the functions of the functional units, and sample and test throughout the entire process; Step S3. Test Data Analysis: Based on steps S1 and S2, and combined with the actual influent water quality, water quantity and process operating parameters, calculate the theoretical conversion and actual removal of pollutants in the functional units. Through data comparison, evaluate whether the biological system has fully realized its phosphorus and nitrogen removal potential. If there is potential for improvement, formulate a process optimization plan for the nitrogen and phosphorus removal biological system in combination with the measured actual environmental parameters and sludge performance parameters. In step S1, the pretreatment of the returned sludge includes the following steps: Take 3-5 L of returned sludge and deoxygenate it until DO < 0.2 mg / L. Add 10-15 mg of potassium dihydrogen phosphate (KH2PO4) to the sludge (calculated as P). After sludge-water separation, test the phosphate (PO4) content of the supernatant. 3－ -P concentration, stir for 5-10 minutes, and test again to ensure PO4 concentration. 3－ -P concentration remains unchanged; The amount of the rapid carbon source added ensures that the initial COD in the mixture is not less than 60 mg / L, and the mixture is stirred at a low speed of 50-100 rpm. In step S2, the core test indicators include environmental parameters and water quality parameters; The water quality parameters include NO3-N and PO4 in the supernatant of activated sludge at the end of the pre-anoxic section. 3- -P; NO3-N and PO4- in the supernatant of activated sludge at the end of the anaerobic stage 3- -P; PO4 in the supernatant of activated sludge at the end of the denitrification and phosphorus removal stage. 3- -P and NO3-N; SCOD, NO3-N, PO4- in the supernatant of activated sludge at the end of the first anoxic stage 3- -P; NH4+ in the supernatant of activated sludge at the beginning, middle, and end of the first aerobic stage. + -N, NO3-N, PO4 3- -P; SCOD and PO4 in the supernatant of activated sludge at the end of the second anoxic stage 3- -P and NO3-N; NH4+ in the supernatant of activated sludge from the front, middle, and rear sections of the second aerobic stage. + -N, NO3-N, PO4 3- -P; NO3-N and PO4- in the effluent from the secondary sedimentation tank weir 3- -P; NO3-N and PO4- in the supernatant of activated sludge at the inlet of the mixed liquor return zone into the anoxic tank. 3- -P; NO3-N and PO4 in the activated sludge at the inlet of the pre-anoxic zone in the sludge return zone 3- -P, the supernatant of activated sludge from each functional unit needs to be sampled on-site and then quickly separated into sludge and water. The environmental parameters include DO and ORP at the front end of the pre-anoxic zone; ORP in the anaerobic zone; ORP in the denitrification and phosphorus removal zone; ORP and pH in the first anoxic zone; DO, ORP, and pH at the front, middle, and end of the first aerobic zone; DO and ORP at the end of the deoxygenation zone; DO and ORP at the end of the second anoxic zone; DO, ORP, and pH at the front, middle, and end of the second aerobic zone; DO and ORP in the secondary sedimentation tank; DO at the inlet of the mixed liquor return to the anoxic tank; and DO at the inlet of the sludge return zone to the pre-anoxic zone. All of the above environmental parameters need to be tested on-site at the functional unit. In step S3, when the theoretical conversion amount of pollutants minus the actual removal amount is ≥3 mg / L, a process optimization plan is formulated for the nitrogen and phosphorus removal biological system based on the measured actual environmental parameters and sludge performance parameters.

2. The rapid detection method for performance evaluation of a nitrogen and phosphorus removal biological system according to claim 1, characterized in that, The sludge microbial denitrification and phosphorus removal rate test in step S1 includes the following steps: (1) Add sufficient rapid carbon source to the pretreated return sludge and stir. Take the mixture at different time points, separate the sludge and water, and test the PO4 in the supernatant. 3－ -P concentration, after a duration of not less than 30 min, calculate the nitrate NO3-N concentration standard in the supernatant, and add 5~10 mg / L potassium nitrate KNO3 as N; take the mixture at different time points, separate the mud and water, and test the NO3-N concentration in the supernatant. After a reaction time of not less than 1 h, combine with the remaining PO4. 3- To adjust the concentrations of -P and NO3-N, add appropriate amounts of KH2PO4 and ammonium chloride (NH4Cl) to ensure the concentration of PO4 in the supernatant. 3- -P concentration not less than 5 mg / L, NH4 + Aeration was initiated when the NH4+ concentration was not less than 10 mg / L. When the DO concentration was >2 mg / L, samples of the mixed liquor were taken at different time points. After sludge-water separation, the NH4+ concentration in the supernatant was tested. ＋ -N, the experiment ended after the duration was greater than 1 hour, and the concentration of volatile matter in the mixed liquor (MLVSS) was measured. (2) Draw PO4 separately 3－ -P ~ t、NO3-N ~ t、NH4 ＋ -N ~ t linear relationship diagram, and combined with MLVSS to calculate the phosphorus release rate of activated sludge in the anaerobic section, the denitrification and phosphorus removal rate in the anoxic section, and the nitrification and phosphorus uptake rate in the aerobic section.

3. The rapid detection method for performance evaluation of a nitrogen and phosphorus removal biological system according to claim 1, characterized in that, The test functional units for the full-process biological system test described in step S2 include a pre-anoxic section, an anaerobic section, a denitrification and phosphorus removal section, a first anoxic section, a first aerobic section, an oxygen depletion section, a second anoxic section, a second aerobic section, and a secondary sedimentation tank. The mixed liquor flows back from the outlet of the first aerobic section to the inlet of the first anoxic section and from the outlet of the second aerobic section to the inlet of the second anoxic section. The sludge flows back from the outlet of the secondary sedimentation tank to the inlet of the pre-anoxic section.

4. The rapid detection method for performance evaluation of a nitrogen and phosphorus removal biological system according to claim 3, characterized in that, The sampling points in step S2 include: the front and end of the pre-anoxic section; the end of the anaerobic section; the end of the denitrification and phosphorus removal section; the end of the first anoxic section; the front, middle, and end of the first aerobic section; the end of the deoxygenation section; the end of the second anoxic section; the front, middle, and end of the second aerobic section; the effluent weir of the secondary sedimentation tank; the front of the mixed liquor entering the anoxic section; and the front of the sludge return entering the pre-anoxic section.

5. The rapid detection method for performance evaluation of a nitrogen and phosphorus removal biological system according to claim 1, characterized in that, In step S2, the core test indicators also include sludge performance parameters, which include the color, water temperature, and sludge settling ratio (SV) of the activated sludge at the end of the first and second aerobic stages. 30 MLSS concentration of sludge, MLVSS concentration of sludge volatile matter, and phosphorus content of sludge.

6. The rapid detection method for performance evaluation of a nitrogen and phosphorus removal biological system according to claim 1, characterized in that, The test data analysis described in step S3 specifically includes the following steps: By testing the nitrogen and phosphorus removal rate of sludge microorganisms, the pollutant conversion rate corresponding to the functional unit of the biological system was obtained. Combined with the parameters of the unit, including influent water quality, water quantity, sludge concentration, and hydraulic retention time, the theoretical conversion amount of pollutants by the functional unit was calculated. By conducting full-process testing of the biological system and combining it with material balance, the actual amount of pollutants removed by this functional unit was calculated.

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