Transformation method for coupling partial denitrification and anaerobic ammonia oxidation in urban sewage treatment

Abstract

The invention belongs to the technical field of town sewage treatment, and discloses a partial denitrification coupled anaerobic ammonia oxidation transformation method for town sewage treatment, which is characterized in that a partial denitrification coupled anaerobic ammonia oxidation system is arranged at the downstream of an original treatment system of a town sewage treatment plant; and the inflow water flow entering the original treatment system and the partial denitrification coupling anaerobic ammonia oxidation system is adjusted according to the ratio of NO3 <-> / NH4 < + >, so that the ratio of NO3 <-> / NH4 < + > is within the optimal ratio range of 1.2-1.4, and anaerobic ammonia oxidation is carried out, so that the upgrading and reconstruction of the existing municipal sewage treatment plant are minimally modified, the upgrading and reconstruction period is shortened, and the engineering cost is saved.

Description

Technical Field

[0001] This application belongs to the technical field of urban sewage treatment, and particularly relates to a method for transforming partial denitrification coupled with anaerobic ammonium oxidation in urban sewage treatment. Background Technique

[0002] Nitrogen is one of the basic pollutant removal targets in urban sewage treatment plants. Most existing urban sewage treatment plants adopt the traditional complete nitrification and denitrification biological nitrogen removal process. The conversion of nitrogen includes assimilation, ammonification, nitrification, and denitrification. However, the conversion process from combined nitrogen to gaseous nitrogen and thus fundamentally removing nitrogen pollutants mainly occurs through nitrification and denitrification reactions. The nitrification reaction is a biochemical reaction that oxidizes ammonia nitrogen to nitrite nitrogen and nitrate nitrogen under aerobic conditions; the denitrification reaction refers to the reaction that reduces nitrite nitrogen and nitrate nitrogen to gaseous nitrogen (N 2 ), or N 2 O, NO, which can be basically expressed as: Nitrification reaction: NH 4 + →NO 2 - →NO 3 - ; Denitrification reaction: NO 3 - →NO 2 - →NO→N 2 O→N 2 ; However, in the nitrification reaction, aeration will consume a large amount of energy. Oxidizing 1 mol of NH 4 + to NO 2 - requires 1.5 mol of O 2 , and oxidizing to get NO 3 - requires 2.0 mol of O 2 . In the denitrification reaction, denitrifying 1 g of NO 3 - requires 2.86 g of organic matter, denitrifying 1 g of NO 2 - requires 1.72 g of organic matter, and N 2 O is a greenhouse gas. Like other greenhouse gases such as carbon dioxide and methane, it has an impact on the earth's climate system, which has become the main problem faced by current sewage treatment plants in nitrogen removal.

[0003] In recent years, the anaerobic ammonium oxidation process has been considered a solution with great application prospects. It can be carried out through a completely autotrophic bacterial mechanism. Anaerobic ammonium oxidizing bacteria use NO2 - -N serves as an electron acceptor to directly oxidize NH 4 + -N, and simultaneously converts both into nitrogen gas (N 2 ), which has the advantages of reducing carbon consumption, decreasing sludge production, and reducing N 2 O emissions, etc. In the biological treatment system, nitrification reaction (NH 4 + →NO 2 - →NO 3 - ) occurs in the aerobic zone, and denitrification reaction (NO 3 - →NO 2 - →NO→N 2 O→N 2 ) occurs in the anoxic zone. However, under steady state, there will be no accumulation of NO 2 - -N in the biological treatment system, and it will not coexist with NH 4 + -N at the same time and in the same space. Therefore, the research on the application of the anaerobic ammonium oxidation process in treating actual sewage is still limited.

[0004] Currently, due to the increasing domestic sewage and industrial wastewater, the discharge standards are constantly improving, and nitrogen removal is the key and difficult point in the design or upgrading of urban sewage treatment processes. Under the background of the "dual-carbon" era, it has become the main problem faced by current sewage treatment plants. Existing urban sewage treatment plants need to be renovated, but currently, the renovation involves large changes, long construction periods, and high project costs. Therefore, how to achieve the minimum changes while meeting the treatment requirements and applying the anaerobic ammonium oxidation process is an important research direction. Summary of the Invention

[0005] The purpose of this application is to solve the problems of the existing technology and provide a renovation method for partial denitrification coupled with anaerobic ammonium oxidation in urban sewage treatment.

[0006] To solve the technical problems, the technical solution of this application is: a renovation method for partial denitrification coupled with anaerobic ammonium oxidation in urban sewage treatment, including the following steps: Step 1: Set up a partial denitrification coupled with anaerobic ammonium oxidation system downstream of the original treatment system in the urban sewage treatment plant; Step 2: Divide the total influent flow rate Q of the urban sewage treatment plant into two parts, with a part of the influent flow rate q1 entering the original treatment system and the other part of the influent flow rate q2 entering the partial denitrification coupled with anaerobic ammonium oxidation system; Step 3: According to the NO in the effluent of the original treatment system 3- -N concentration and the NH in the influent of the municipal wastewater treatment plant 4 + -N concentration to calculate the influent flow rate q1 entering the original treatment system and the influent flow rate q2 entering the partial denitrification coupled anaerobic ammonium oxidation system, so that the ratio of NO 3 - / NH 4 + is within the optimal ratio range R; Step 4: Mix the effluent of the original treatment system and the influent of the partial denitrification coupled anaerobic ammonium oxidation system for anaerobic ammonium oxidation reaction to realize the transformation of the municipal wastewater treatment plant.

[0007] Preferably, in the step 1, the partial denitrification coupled anaerobic ammonium oxidation system includes a partial denitrification coupled anaerobic ammonium oxidation reactor. The control temperature of the partial denitrification coupled anaerobic ammonium oxidation reactor is 25 °C, the control rotation speed is 70 revolutions per minute, and each operation cycle of the partial denitrification coupled anaerobic ammonium oxidation reactor is 4 hours: including 5 minutes of influent, 190 minutes of stirring, 30 minutes of sedimentation, 10 minutes of effluent, and 5 minutes of idle. The volume exchange ratio of the partial denitrification coupled anaerobic ammonium oxidation reactor is 50%, and the filling rate of the anaerobic ammonium oxidation bacteria packing in the partial denitrification coupled anaerobic ammonium oxidation reactor is 15%.

[0008] Preferably, when constructing the partial denitrification coupled anaerobic ammonium oxidation reactor, the activated sludge is taken from the anoxic zone of the municipal wastewater treatment plant, and the MLSS is 2323 ± 62 mg·L -1 , the MLVSS is 1713 ± 34 mg·L -1 , the anaerobic ammonium oxidation bacteria packing is taken from a fixed-bed biofilm reactor, and the specific surface area of the anaerobic ammonium oxidation bacteria packing is 500 m 2 ·m -3 , the nitrogen load is 0.39 mgNH 4 + -N·(m 3 ·d) -1 , and the maximum activity is 122.25 mgN·(L·d) -1 .

[0009] Preferably, the step 3 is specifically as follows: Step 3-1: Set the optimal ratio range of NO 3 - / NH 4 + as the parameter R, the NO 3 - -N concentration in the effluent of the original treatment system of the municipal wastewater treatment plant is a, and the NH in the influent of the municipal wastewater treatment plant 4 +If the -N concentration is b, then the NO 3 - -N and NH 4 + -N concentrations satisfy the following formula: a = Rb; Step 3-2: Assume that all the effluent from the original treatment system of the municipal wastewater treatment plant enters the partial denitrification coupled with anaerobic ammonium oxidation system, then the total NO 3 - -N concentration is fa, where f is the ratio of the influent flow rate q1 entering the original treatment system to the total influent flow rate Q; and the total NH 4 + -N concentration entering the partial denitrification coupled with anaerobic ammonium oxidation system is (1 - f)b, then the following formula can be obtained: fa = R(1 - f)b; The following formula can be calculated: ; Step 3-3: When the total daily influent flow rate of the municipal wastewater treatment plant is Q, the formula for calculating the influent flow rate q1 entering the original treatment system is: q1 = fQ; The following formula can be calculated: ; Then the formula for calculating the influent flow rate q2 entering the partial denitrification coupled with anaerobic ammonium oxidation system is: q2 = Q - q1; The influent flow rate q1 entering the original treatment system and the influent flow rate q2 entering the partial denitrification coupled with anaerobic ammonium oxidation system are obtained, and the ratio of NO 3 - / NH 4 + is within the optimal ratio range R.

[0010] Preferably, the parameter R = 1.2 - 1.4.

[0011] Preferably, after obtaining the influent flow rate q2 entering the partial denitrification coupled with anaerobic ammonium oxidation system, calculate the carbon source dosage W, and the specific calculation is as follows: Let the COD total / TN inf ratio be the parameter k, then the daily required COD total amount of the partial denitrification coupled with anaerobic ammonium oxidation system is W 需 , then the following formula can be obtained: W 需 = kTN inf Among them, the nitrogen source TN entering the partial denitrification coupled with anaerobic ammonium oxidation system daily inf The calculation formula is as follows: TN inf =(fa+(1 - f)b)Q; The calculation formula for the carbon source dosage W is as follows: W 实 =BOD(1 - f)Q; W = W 需 -W 实 ; Among them, BOD is the measured biochemical oxygen demand, mg·L -1 .

[0012] Preferably, the parameter k = 2.6~3.0.

[0013] Compared with the prior art, the advantages of this application are as follows: (1) This application discloses a method for transforming partial denitrification coupled with anaerobic ammonium oxidation in urban sewage treatment. A partial denitrification coupled with anaerobic ammonium oxidation system is set downstream of the original treatment system in the urban sewage treatment plant, and the influent flow rates into the original treatment system and the partial denitrification coupled with anaerobic ammonium oxidation system are adjusted by the ratio of NO 3 - / NH 4 + so that the ratio of NO 3 - / NH 4 + is within the optimal ratio range of 1.2~1.4 for anaerobic ammonium oxidation, enabling the minimum modification for the upgrading transformation of existing urban sewage treatment plants, shortening the upgrading transformation period, and saving project costs; (2) Without changing the original treatment system, this application directly mixes the effluent of the original treatment system and the influent of the partial denitrification coupled with anaerobic ammonium oxidation system for anaerobic ammonium oxidation reaction. Among them, the influent of the partial denitrification coupled with anaerobic ammonium oxidation system does not pass through the original biochemical system and does not participate in complete nitrification and denitrification, so it saves power consumption and carbon source and greatly reduces the transformation cost; (3) According to the optimal ratio of NO 3 - / NH 4 + and the ratio of COD total / TN inf , through the anaerobic ammonium oxidation reaction in the partial denitrification coupled with anaerobic ammonium oxidation system, good nitrogen removal performance is achieved, no external carbon source is required, and cost reduction and efficiency improvement are realized; (4) The anaerobic ammonium oxidation reaction is carried out in this application through a partial denitrification coupled with anaerobic ammonium oxidation system, which does not require aeration, achieving good nitrogen removal performance, greatly saving power consumption, and contributing to carbon neutrality. Description of the Drawings

[0014] Figure 1 It is a schematic diagram of the transformation of a method for partial denitrification coupled with anaerobic ammonium oxidation in urban sewage treatment in this application; Figure 2 It is a graph of the changes in nitrogen concentration, COD, and pH values during a typical cycle; Figure 3 It is a verification graph of the nitrogen removal performance of a method for partial denitrification coupled with anaerobic ammonium oxidation in urban sewage treatment in this application; Figure 4 For COD total / TN inf and TN eff Corresponding change graph.

[0015] Description of the reference numerals: 1. Original treatment system, 2. Partial denitrification coupled with anaerobic ammonium oxidation system. Specific Embodiments

[0016] The following describes this application in detail with reference to the drawings and specific embodiments, but this application is not limited to these embodiments. This application covers any substitutions, modifications, equivalent methods, and solutions made within the essence and scope of this application. In order to enable the public to have a thorough understanding of this application, specific details are described in detail in the following embodiments of this application, and those skilled in the art can fully understand this application without the description of these details.

[0017] This application provides a method for transforming partial denitrification coupled with anaerobic ammonium oxidation in urban sewage treatment. In this method, TN ≤ 5 mg / L, which can meet the TN emission requirements of TN ≤ 15 mg / L in the "Integrated Sewage Discharge Standard for the Yellow River Basin in Shaanxi Province" (DB61 / 224 - 2018) and TN ≤ 12 mg / L in the surface water quality standard of Class IV. It provides technical support and operable design parameters for the design of urban sewage treatment processes, upgrading and transformation, or more stringent total nitrogen emission requirements in the future, achieving the purpose of low-carbon, green, environmental protection, and sustainable development.

[0018] As Figure 1 shown, this application discloses a method for transforming partial denitrification coupled with anaerobic ammonium oxidation in urban sewage treatment, including the following steps: Step 1: Set up a partial denitrification coupled with anaerobic ammonium oxidation system 2 downstream of the original treatment system 1 in the urban sewage treatment plant; Step 2: Divide the total influent flow rate Q of the municipal wastewater treatment plant into two parts. One part of the influent flow rate q1 enters the original treatment system 1, and the other part of the influent flow rate q2 enters the partial denitrification coupled with anaerobic ammonium oxidation system 2; Step 3: According to the NO 3 - -N concentration in the effluent of the original treatment system 1 and the NH 4 + -N concentration in the influent of the municipal wastewater treatment plant, calculate the influent flow rate q1 entering the original treatment system 1 and the influent flow rate q2 entering the partial denitrification coupled with anaerobic ammonium oxidation system 2, so that the ratio of NO 3 - / NH 4 + is within the optimal ratio range R; Step 4: Mix the effluent of the original treatment system 1 and the influent of the partial denitrification coupled with anaerobic ammonium oxidation system 2 for anaerobic ammonium oxidation reaction to realize the transformation of the municipal wastewater treatment plant.

[0019] Preferably, in step 1, the partial denitrification coupled with anaerobic ammonium oxidation system 2 includes a partial denitrification coupled with anaerobic ammonium oxidation reactor. The control temperature of the partial denitrification coupled with anaerobic ammonium oxidation reactor is 25°C, the control rotation speed is 70 revolutions per minute, and each operation cycle of the partial denitrification coupled with anaerobic ammonium oxidation reactor is 4 hours: including 5 minutes of influent, 190 minutes of stirring, 30 minutes of sedimentation, 10 minutes of effluent, and 5 minutes of idle. The volume exchange ratio of the partial denitrification coupled with anaerobic ammonium oxidation reactor is 50%, and the filling rate of the anaerobic ammonium oxidation bacteria packing in the partial denitrification coupled with anaerobic ammonium oxidation reactor is 15%.

[0020] Preferably, when constructing the partial denitrification coupled with anaerobic ammonium oxidation reactor, the activated sludge is taken from the anoxic zone of the municipal wastewater treatment plant, with an MLSS of 2323 ± 62 mg·L -1 , an MLVSS of 1713 ± 34 mg·L -1 , the anaerobic ammonium oxidation bacteria packing is taken from a fixed-bed biofilm reactor, the specific surface area of the anaerobic ammonium oxidation bacteria packing is 500 m 2 ·m -3 , the nitrogen load is 0.39 mgNH 4 + -N·(m 3 ·d) -1 , and the maximum activity is 122.25 mgN·(L·d) -1 .

[0021] Preferably, step 3 is specifically as follows: Step 3-1: Let NO 3 - / NH4 + The optimal ratio range is parameter R. The concentration of NO 3 - -N in the effluent of the original treatment system 1 of the urban sewage treatment plant is a, and the concentration of NH 4 + -N in the influent of the urban sewage treatment plant is b. Then, the concentrations of NO 3 - -N and NH 4 + -N entering the partial denitrification coupled with anaerobic ammonium oxidation system 2 satisfy the following formula: a = Rb; Step 3-2: Assume that all the effluent of the original treatment system 1 of the urban sewage treatment plant enters the partial denitrification coupled with anaerobic ammonium oxidation system 2. Then, the total concentration of NO 3 - -N is fa, where f is the ratio of the influent flow rate q1 of the original treatment system 1 to the total influent flow rate Q; and the total concentration of NH 4 + -N entering the partial denitrification coupled with anaerobic ammonium oxidation system 2 is (1 - f)b. Then, the following formula can be obtained: fa = R(1 - f)b; The following formula can be calculated: ; Step 3-3: When the total daily influent flow rate of the urban sewage treatment plant is Q, the calculation formula for the influent flow rate q1 of the original treatment system 1 is: q1 = fQ; The following formula can be calculated: ; Then, the calculation formula for the influent flow rate q2 of the partial denitrification coupled with anaerobic ammonium oxidation system 2 is: q2 = (1 - f)Q; q2 = Q - q1; The influent flow rate q1 of the original treatment system 1 and the influent flow rate q2 of the partial denitrification coupled with anaerobic ammonium oxidation system 2 are obtained, and the ratio of NO 3 - / NH 4 + is within the optimal ratio range R.

[0022] Preferably, the parameter R = 1.2 - 1.4.

[0023] Preferably, after obtaining the influent flow rate q2 of the partial denitrification coupled with anaerobic ammonium oxidation system 2, calculate the carbon source dosage W. The specific calculation is as follows: Let COD total / TN inf If the ratio is the parameter k, then the daily required COD of the partial denitrification coupled with anammox system 2 total is W 需 , then the following formula can be obtained: W 需 = kTN inf Among them, the nitrogen source TN entering the partial denitrification coupled with anammox system 2 daily inf The calculation formula is: TN inf = (fa + (1 - f)b)Q; The calculation formula for the carbon source dosage W is: W 实 = BOD(1 - f)Q; W = W 需 - W 实 ; Among them, BOD is the measured biochemical oxygen demand, mg·L -1 .

[0024] Preferably, the parameter k = 2.6 - 3.0.

[0025] A method for transforming a partial denitrification coupled with anammox in urban sewage treatment in this application includes three parts: The first part is the determination of the optimal NO 3 - / NH 4 + ratio; The second part is the construction of a transformation model for partial denitrification coupled with anammox in urban sewage treatment; The third part is the model experiment verification.

[0026] (1) Optimal NO 3 - / NH 4 + ratio: Set up the partial denitrification coupled with anammox reactor used in the laboratory. This reactor has been operating stably in the laboratory for two years, and its effective volume is 5L. The experimental control temperature is 25°C, and the constant-speed stirring system controls the rotation speed at 70 revolutions per minute. Each operation cycle of the reactor is 4 hours: including 5 minutes of water inlet, 190 minutes of stirring, 30 minutes of sedimentation, 10 minutes of water outlet, and 5 minutes of idle time; The volume exchange ratio of the reactor is 50%, and the filling rate of anammox bacteria packing in the reactor is 15%. When constructing the reactor, the activated sludge is taken from the anoxic zone of the ninth sewage treatment plant, and the MLSS is 2323 ± 62 mg·L -1 , and the MLVSS is 1713 ± 34 mg·L -1 , and the anammox bacteria packing is taken from the fixed-bed biofilm reactor that has been operating stably in the laboratory for 2 years. The specific surface area of the packing is 500m2 ·m -3 , the nitrogen load is 0.39 mgNH 4 + -N·(m 3 ·d) -1 , and the maximum activity is 122.25 mgN·(L·d) -1 .

[0027] As Figure 2 shown, it is a typical diagram of the changes in nitrogen concentration, COD, and pH value during a cycle. The primary effluent of the municipal wastewater treatment plant (mainly containing NH 4 + -N and organic matter) and the secondary effluent (the original treatment system, mainly containing NO 3 - -N) are mixed in different proportions and enter the reactor. After operating for 90 days, the results show that in the range where the NO 3 - / NH 4 + ratio is 1.2 - 1.4 and the COD total / TN inf ratio is 2.6 - 3.0, the partial denitrification coupled with anaerobic ammonium oxidation retrofit method can have good nitrogen removal effect on municipal wastewater.

[0028] (2) Construction of a retrofit model for partial denitrification coupled with anaerobic ammonium oxidation in municipal wastewater treatment: As Figure 1 shown, the total influent flow rate Q (m 3 ·d -1 ) of the municipal wastewater treatment plant is divided into two parts. One part still uses the original treatment system 1 (mostly traditional A / O or A 2 / O process), and the other part enters the partial denitrification coupled with anaerobic ammonium oxidation system 2.

[0029] Assume that the ratio of the influent flow rate q1 entering the original treatment system 1 to the total influent flow rate Q is f , then the flow rate entering the partial denitrification coupled with anaerobic ammonium oxidation system 2 is (1 - f ); Assume that the influent of the municipal wastewater treatment plant only contains NH 4 + -N and organic matter, and the effluent of the original treatment system 1 only contains NO 3 - -N (the secondary effluent COD is considered an undegradable COD and can be ignored). Design the mixing of the effluent of the original treatment system 1 and the wastewater of the partial denitrification coupled with anaerobic ammonium oxidation system 2 to provide NO 3 - -N for the partial denitrification process 1) Let the optimal ratio range of NO 3 - / NH 4 + be the parameter R (R = 1.2 - 1.4); the NO 3 - -N concentration in the effluent of the original treatment system 1 is a , and the NH 4 + -N concentration in the influent of the urban sewage treatment plant is b. Then, the NO 3 - -N and NH 4 + -N concentrations satisfy the following formula (1): a = Rb (1); Assume that all the effluent of the original treatment system 1 enters the partial denitrification coupled anaerobic ammonium oxidation system 2. Then, the NO 3 - -N concentration is fa; and the NH 4 + -N concentration entering the partial denitrification coupled anaerobic ammonium oxidation system 2 is (1 - f)b. Then, the formula (2) can be obtained: fa = R(1 - f)b (2); Calculating gives formula (3): (3); When the total daily influent flow of the urban sewage treatment plant is Q (m 3 ·d -1 ), then the calculation formula for the influent flow q1 entering the original treatment system 1 is formula (4): q1 = fQ; (4); Then, the calculation formula for the influent flow q2 entering the partial denitrification coupled anaerobic ammonium oxidation system 2 is formula (5): q2 = Q - q1 (5); 2) Let the COD total / TN inf ratio be the parameter k (k = 2.6 - 3.0). Then, the daily required COD total quantity for the partial denitrification coupled anaerobic ammonium oxidation system 2 is W 需 . The formula (6) can be obtained: W 需 = kTN inf (6); Among them, for a general urban sewage treatment plant, the nitrogen source TN infThe calculation formula is (7): TN inf =(fa+(1 - f)b)Q (7); The calculation formula for the carbon source dosage W is (8): W 实 =BOD(1 - f)Q; W = W 需 -W 实 (8); Wherein, BOD is the measured biochemical oxygen demand, mg·L -1 .

[0030] (3) Model experiment verification: To verify the obtained optimal ratio range (NO 3 - / NH 4 + The ratio is 1.2 - 1.4, and the COD total / TN inf The ratio is 2.6 - 3.0), the experiment is designed within this ratio range, and the verification water sample is taken from the Second Sewage Treatment Plant in Gaoxin.

[0031] During the period from 2018 to 2019, the maximum value of the influent TN in the Second Sewage Treatment Plant in Gaoxin District was 41mg·L -1 , and the average value was 24.64mg·L -1 , NH 4 + -N maximum value was 24.9mg·L -1 , and the average value was 9.29mg·L -1 . 3 - / NH 4 + was approximately 1.58 - 1.80, and the actual NO 3 - / NH 4 + ratio was lower than this range. The total nitrogen in the influent of the Second Sewage Treatment Plant in Gaoxin District does not mainly exist in the form of NH 4 + -N, because its influent is composed of the sewage from the Samsung Electronics Industrial Park (containing a high NO 3 - -N) and a small amount of domestic sewage (containing a small amount of NH 4 + -N and organic matter), so the influent of the water plant contains some reaction substrates required for the partial denitrification coupled with anaerobic ammonium oxidation process. Therefore, all the influent of this water plant can enter the reactor of the partial denitrification coupled with anaerobic ammonium oxidation system 2, and f = 0. And the domestic sewage in the influent of this water plant is less, and the COD5 The TN / COD is about 1.14 - 1.42, and the biodegradable organic matter is seriously insufficient to meet the requirements of denitrification. Therefore, the water treatment plant selects sodium acetate as the external carbon source, and the daily C / N is as high as over 5.

[0032] During the verification period, the average influent NO 3 - -N and NH 4 + -N concentrations of the second sewage treatment plant in the high-tech zone are 16.67 ± 0.51 mg·L -1 and 12.14 ± 0.48 mg·L -1 , and NO 3 - / NH 4 + is in the range of 1.3 - 1.4, which is included in the optimal ratio range (NO 3 - / NH 4 + is 1.2 - 1.4).

[0033] Figure 3 This is the denitrification performance verification diagram of the partial denitrification coupled with anaerobic ammonium oxidation transformation method for urban sewage treatment in this application, verifying the influent denitrification performance of the second sewage treatment plant in the high-tech zone; the average effluent NO 3 - -N, NH 4 + -N, and TN concentrations are 3.76 ± 0.53 mg·L -1 , 0.34 ± 0.21 mg·L -1 , and 4.39 ± 0.95 mg·L -1 respectively. The average effluent NRR, ARR, and TNRR are 77.09 ± 1.03%, 97.34 ± 1.64%, and 84.73 ± 1.77% respectively, showing good denitrification performance.

[0034] Figure 4 This is the corresponding change diagram of COD total / TN inf and TN eff Since the proportion of domestic sewage in the influent of the second sewage treatment plant in the high-tech zone is small, the required amount of external carbon source is high. It is verified that when COD total / TN inf is 2.8 - 3.0, which is included in the optimal ratio range (COD total / TN inf is 2.6 - 3.0), the effluent NO 3 - -N concentration can be lower than 5 mg·L -1As calculated by constructing the model formula (8) below, the sewage treatment plant can save at least 40% - 44% of the carbon source dosage per day.

[0035] In addition, through the actual sewage verification of the Ninth Sewage Treatment Plant in Xi'an, it is found that when the flow ratio of q1:q2 is 5:1, that is, in the range where the NO 3 - / NH 4 + ratio is 1.2 - 1.4 and the C / T ratio is 2.6 - 3.0; the hydraulic retention time is 8 h and TN ≤ 3 mg / L; the hydraulic retention time is 4 h and TN ≤ 5 mg / L; the hydraulic retention time is 2 h and TN ≤ 8 mg / L. The effluent TN standard is far higher than the water quality standard with a maximum TN of 12 mg / L in Class IV, and it can be applied to more stringent TN upgrading, as well as sewage treatment with TN removal requirements in aspects such as the upgrading and transformation of township enterprises, small sewage treatment plants, and river regulation.

[0036] The present application discloses a method for retrofitting partial denitrification coupled with anaerobic ammonium oxidation in urban sewage treatment. A partial denitrification coupled with anaerobic ammonium oxidation system is set downstream of the original treatment system in the urban sewage treatment plant, and the influent flow rates into the original treatment system and the partial denitrification coupled with anaerobic ammonium oxidation system are adjusted by the ratio of NO 3 - / NH 4 + so that the ratio of NO 3 - / NH 4 + is within the optimal ratio range of 1.2 - 1.4 for anaerobic ammonium oxidation, enabling the minimum modification for the upgrading and transformation of existing urban sewage treatment plants, shortening the upgrading and transformation period, and saving project costs.

[0037] Without changing the original treatment system, the present application directly mixes the effluent of the original treatment system with the influent of the partial denitrification coupled with anaerobic ammonium oxidation system for anaerobic ammonium oxidation reaction. The influent of the partial denitrification coupled with anaerobic ammonium oxidation system does not pass through the original biochemical system and does not participate in complete nitrification and denitrification, thus saving power consumption and carbon source and greatly reducing the transformation cost.

[0038] Based on the optimal NO 3 - / NH 4 + ratio and COD total / TN inf ratio, anaerobic ammonium oxidation reaction is carried out through the partial denitrification coupled with anaerobic ammonium oxidation system, achieving good nitrogen removal performance without the need for external carbon source, and realizing cost reduction and efficiency improvement.

[0039] This application conducts anaerobic ammonium oxidation reactions through a partial denitrification-coupled anaerobic ammonium oxidation system, eliminating the need for aeration, achieving excellent nitrogen removal performance, significantly saving power consumption, and contributing to carbon neutrality.

[0040] The above has detailed the preferred embodiments of this application. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the purpose of this application.

[0041] Many other changes and modifications can be made without departing from the concept and scope of this application. It should be understood that this application is not limited to specific embodiments, and the scope of this application is defined by the appended claims.

Claims

1. A method for partial denitrification coupled anaerobic ammonium oxidation transformation of urban sewage treatment, characterized in that: The following steps are involved: Step 1: Install a partial denitrification coupled anaerobic ammonium oxidation system (2) downstream of the existing treatment system (1) of the municipal sewage treatment plant; Step 2: The total influent flow Q of the municipal sewage treatment plant is divided into two parts, one part of the influent flow q1 enters the original treatment system (1), and the other part of the influent flow q2 enters the partial denitrification coupled anaerobic ammonium oxidation system (2); Step 3: According to the original treatment system (1) NO3 in the effluent - -N concentration and NH4 in the influent of municipal sewage treatment plants + -N concentration is calculated by the influent flow rate q1 entering the original treatment system (1) and the influent flow rate q2 entering the partial denitrification coupled anaerobic ammonium oxidation system (2), so that NO3 - / NH4 + The ratio is within the optimal ratio range R; Step 4: The effluent of the original treatment system (1) and the influent of part of the denitrification coupled anaerobic ammonium oxidation system (2) are mixed to carry out anaerobic ammonium oxidation reaction, thereby realizing the transformation of the urban sewage treatment plant.

2. A method for partial denitrification coupled anaerobic ammonium oxidation transformation of urban sewage treatment according to claim 1, characterized in that: The partial denitrification coupled anaerobic ammonium oxidation system (2) in step 1 comprises a partial denitrification coupled anaerobic ammonium oxidation reactor, the control temperature of the partial denitrification coupled anaerobic ammonium oxidation reactor is 25° C., the control speed is 70 rpm, each operation cycle of the partial denitrification coupled anaerobic ammonium oxidation reactor is 4 hours, including 5 minutes of water inlet, 190 minutes of stirring, 30 minutes of sedimentation, 10 minutes of water outlet, and 5 minutes of idle time, the volume exchange ratio of the partial denitrification coupled anaerobic ammonium oxidation reactor is 50%, and the filling rate of the anaerobic ammonium oxidizing bacteria filler in the partial denitrification coupled anaerobic ammonium oxidation reactor is 15%.

3. A method for partial denitrification coupled anaerobic ammonium oxidation transformation of urban sewage treatment according to claim 2, characterized in that: When the partial denitrification coupled anaerobic ammonium oxidation reactor was constructed, the activated sludge was taken from the anoxic zone of the urban sewage treatment plant, and the MLSS was 2323±62 mg·L -1 , MLVSS is 1713±34mg·L -1 The anaerobic ammonium oxidizing bacteria filler was taken from the fixed-bed biofilm reactor. The specific surface area of ​​the anaerobic ammonium oxidizing bacteria filler was 500m 2 ·m -3 , nitrogen load is 0.39mgNH4 + -N·(m 3 d) -1 , the maximum activity is 122.25mgN·(L·d) -1 .

4. A method for partial denitrification coupled anaerobic ammonium oxidation transformation of urban sewage treatment according to claim 1, characterized in that: The step 3 is specifically as follows: Step 3-1: Set NO3 - / NH4 + The optimal ratio range is parameter R, the original treatment system of the urban sewage treatment plant (1) NO3 - -N concentration is a, NH4 in the influent of urban sewage treatment plant + -N concentration is b, then NO3 enters the partial denitrification coupled anaerobic ammonium oxidation system (2) - -N and NH4 + The concentration of -N satisfies the following formula: a=Rb; Step 3-2: Assuming that the effluent from the original treatment system (1) of the municipal sewage treatment plant enters the partial denitrification coupled anaerobic ammonium oxidation system (2), then NO3 - The total concentration of -N is fa, f is the ratio of the influent flow q1 entering the original treatment system (1) to the total influent flow Q; and the NH4 + -N total concentration is (1-f)b, then the following formula is obtained: fa = R(1-f)b; The following formula is calculated: ； Step 3-3: When the total daily inflow of the urban sewage treatment plant is Q, the calculation formula for the inflow flow q1 entering the original treatment system (1) is: q1=fQ; The following formula is calculated: ； The calculation formula for the influent flow rate q2 entering the partial denitrification coupled anaerobic ammonium oxidation system (2) is: q2=Q-q1; The influent flow rate q1 entering the original treatment system (1) and the influent flow rate q2 entering the partial denitrification coupled anaerobic ammonium oxidation system (2) are obtained, and NO3 - / NH4 + The ratio is within the optimal ratio range R.

5. A method for partial denitrification coupled anaerobic ammonium oxidation transformation of urban sewage treatment according to claim 4, characterized in that: The parameter R=1.2~1.

4.

6. A method for partial denitrification coupled anaerobic ammonium oxidation transformation of urban sewage treatment according to claim 4, characterized in that: After obtaining the influent flow rate q2 entering the partial denitrification coupled anaerobic ammonium oxidation system (2), the carbon source dosage W is calculated. The specific calculation is as follows: Set COD total / TN inf The ratio is parameter k, then the daily COD required for partial denitrification coupled anaerobic ammonium oxidation system (2) total The quantity is W 需 , then we get the following formula: W 需 =kTN inf ; Among them, the nitrogen source TN entering the partial denitrification coupled anaerobic ammonium oxidation system (2) every day inf The calculation formula is: TN inf =(fa+(1-f)b)Q; The calculation formula of carbon source dosage W is: W 实 =BOD(1-f)Q; W=W 需 -IN 实 ; Wherein, BOD is the measured biochemical oxygen demand, mg·L -1 .

7. A method for partial denitrification coupled anaerobic ammonium oxidation transformation of urban sewage treatment according to claim 6, characterized in that: The parameter k=2.6~3.0.

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