Device and method for co-treatment of acrylic fiber wastewater and domestic sewage by nitrification-short-cut denitrification coupled with anaerobic ammonia oxidation

Abstract

The device and method for treating acrylic fiber wastewater and domestic sewage by nitrification-short-cut denitrification coupled with anaerobic ammonia oxidation belong to the technical field of biological treatment of industrial wastewater. The acrylic fiber wastewater is first introduced into a full nitrification reactor for nitrification, and the nitrified effluent is introduced into an intermediate water tank. The domestic sewage and the nitrified acrylic fiber wastewater are respectively introduced into a short-cut denitrification upflow reactor by two water pumps in a certain proportion. The short-cut denitrification bacteria utilize the carbon source in the domestic sewage to reduce the nitrate nitrogen to nitrite nitrogen, and the anaerobic ammonia oxidation bacteria utilize the ammonia nitrogen in the domestic sewage and the nitrite nitrogen produced by the short-cut denitrification to perform anaerobic ammonia oxidation, and the byproduct nitrate nitrogen is used as a substrate by the short-cut denitrification bacteria, so that the nitrogen is deeply removed. The carbon source in the domestic sewage is used for reducing the nitrate nitrogen produced by the nitrification of the acrylic fiber wastewater, and the short-cut denitrification / anaerobic ammonia oxidation realizes the deep denitrification of the acrylic fiber wastewater and the domestic sewage under the condition of no additional carbon source.

Description

TECHNICAL FIELD

[0001] The application relates to a device and a method for cooperatively treating acrylic fiber wastewater and domestic sewage through nitration-short-range denitrification coupled anaerobic ammonia oxidation, and belongs to the technical field of biological treatment of industrial wastewater. BACKGROUND

[0002] Acrylic fiber, also known as artificial wool, is a kind of artificial fiber formed by a high-molecular long-chain synthetic polymer and is widely applied to fields such as garment processing, ornament production and preparation of new materials. In the production process of acrylic fiber, acrylic fiber wastewater with the characteristics of high toxicity, high content of refractory organic matter, high N / C and low C / N is generated.

[0003] The separate treatment of acrylic fiber wastewater faces difficulties such as imbalance of nutrient elements, need for a large amount of additional carbon source and low treatment efficiency, while a large amount of biodegradable carbon source exists in domestic sewage, and the cooperative treatment of acrylic fiber wastewater and domestic sewage can reduce the treatment difficulty of acrylic fiber wastewater; the nutrient salts in domestic sewage and acrylic fiber wastewater are complementary to each other, harmful substances are diluted with each other, and the acid-base degree is adjusted, thereby reducing the treatment difficulty of acrylic fiber wastewater, and the soluble organic matter in domestic sewage is used to realize the cooperative denitrification of domestic sewage and acrylic fiber wastewater under the condition of no additional carbon source.

[0004] Anaerobic ammonia oxidation is the most economical and efficient wastewater denitrification technology so far, has the characteristics of no need for additional carbon source, saving aeration, low sludge yield and high denitrification efficiency, and with the deepening of research, the anaerobic ammonia oxidation technology has been applied to the treatment of domestic sewage, landfill leachate, sludge digestion liquid and other wastewaters. Autotrophic denitrification through anaerobic ammonia oxidation needs substrates of ammonia nitrogen and nitrite, and ammonia nitrogen widely exists in domestic sewage and various wastewaters, so how to provide a stable nitrite source for anaerobic ammonia oxidation has become one of the bottlenecks in the development of anaerobic ammonia oxidation technology. As a new nitrite supply method, short-range denitrification can provide sufficient substrate for the anaerobic ammonia oxidation process, and the process can maintain stable and efficient NO2 - generation efficiency, fast reaction rate, simple control and no need for complex control means. Compared with the traditional denitrification denitrification process, the process of coupling short-range denitrification and anaerobic ammonia oxidation not only can save about 80% of the organic carbon source, 50% of the aeration energy consumption, but also can reduce the discharge of excess sludge and greenhouse gases, and is a new type of wastewater denitrification technology with important research value and practical application value.

[0005] However, the growth rate of ANAMMOX bacteria is slow (the highest growth rate is 0.0027h-1h), the generation cycle is long (10-14d), and the activity is easily affected by environmental changes. Generally, biofilm or granulation technology is used in the reactor to separate sludge retention time and hydraulic retention time, so as to achieve the effect of retaining ANAMMOX bacteria. Inoculating granular sludge in the UASB can prolong the sludge retention time of ANAMMOX bacteria, provide a good ecological niche for ANAMMOX bacteria, reduce the influence of external adverse factors, and thus improve the nitrogen removal load of the system and the ability of stable operation. SUMMARY

[0006] The application discloses a device and a method for cooperatively treating acrylic fiber wastewater and domestic sewage by nitrification-short-cut denitrification coupled with ANAMMOX, and particularly relates to the following steps: acrylic fiber wastewater is introduced into an O-SBR for full nitrification, and meanwhile, part of substances toxic and harmful to microorganisms in the acrylic fiber wastewater is removed to a certain extent, for example, SCN- is decomposed into sulfate, carbon dioxide and ammonia nitrogen under aerobic conditions, and phenol is decomposed by microorganisms under aerobic conditions, so that the inhibition on the latter reaction is reduced; the acrylic fiber wastewater and the domestic sewage after full nitrification are mixed at a certain ratio and introduced into a PDA-UASB, short-cut denitrification bacteria utilize carbon sources in the domestic sewage to reduce nitrate nitrogen provided by the acrylic fiber wastewater into nitrite nitrogen, ANAMMOX bacteria utilize the nitrite nitrogen and ammonia nitrogen in the domestic sewage as substrates to perform denitrification, and generate by-product nitrate nitrogen, the nitrate nitrogen is used as the substrate of the short-cut denitrification bacteria again, and is further removed. The granular sludge in the UASB is beneficial to maintaining good ANAMMOX activity, so that the total nitrogen removal rate and removal load of the system are improved.

[0007] The device and method for treating acrylic fiber wastewater and domestic sewage by nitrification-short-cut denitrification coupled with anaerobic ammonia oxidation are characterized by comprising a first water inlet tank (1), a full nitrification sequencing batch reactor (O-SBR) (2), an acrylic fiber wastewater intermediate water tank (3), a second water inlet tank (4), a short-cut denitrification coupled with anaerobic ammonia oxidation upflow anaerobic sludge bed reactor (PDA-UASB) (5), and a water outlet tank (6); the acrylic fiber wastewater enters the O-SBR from the first water inlet tank through a first peristaltic pump (2.1), the O-SBR is provided with a stirrer (2.2), a first dissolved oxygen controller (2.3), a first pH controller (2.4), an aeration device (2.5), and a gas flow meter (2.6), the completely nitrified acrylic fiber wastewater is discharged into the acrylic fiber wastewater intermediate water tank through a first drain valve (2.7); the domestic sewage is stored in the second water inlet tank, the completely nitrified acrylic fiber wastewater and the domestic sewage are pumped into the PDA-UASB by a second peristaltic pump (5.1) and a third peristaltic pump (5.2) respectively, the PDA-UASB is provided with a second dissolved oxygen controller (5.4), a second pH controller (5.5), and a temperature control device (5.6), part of the effluent is returned to the bottom of the PDA-UASB through a sixth peristaltic pump (5.3) at a reflux ratio of 300%-500%, and the remaining effluent is discharged into the water outlet tank.

[0008] The treatment process of the acrylic fiber wastewater and the municipal sewage in the device is as follows: the acrylic fiber wastewater is subjected to full nitrification in the O-SBR, the ammonia nitrogen in the acrylic fiber wastewater is converted into nitrate nitrogen by nitrifying bacteria, the effluent enters the intermediate water tank, is mixed with the domestic sewage at a proper ratio, and enters the PDA-UASB, the organic matter in the domestic sewage provides an electron donor, the nitrate nitrogen is provided by the acrylic fiber wastewater, the nitrate nitrogen is reduced to nitrite nitrogen by denitrifying bacteria, then, the ammonia nitrogen acts as an electron donor, the nitrite nitrogen generated by the denitrifying bacteria acts as an electron acceptor, the nitrogen in the water is converted into nitrogen gas by anaerobic ammonia oxidation bacteria and is diffused into the air to achieve denitrification, and the above process realizes the purpose of denitrification without additional carbon source.

[0009] The device and method for treating acrylic fiber wastewater and domestic sewage by nitrification-short-cut denitrification coupled with anaerobic ammonia oxidation are characterized by comprising the following contents:

[0010] (1) Start-up of O-SBR: The inoculated sludge was the excess sludge from the secondary sedimentation tank of a municipal wastewater treatment plant. The gradient dilution of acrylic fiber wastewater was used as the influent strategy. The gradient dilution of acrylic fiber wastewater was divided into four stages according to the dilution ratio (75%, 50%, 25%, 0). In the first stage, the dilution ratio of acrylic fiber wastewater was 75%. The diluted acrylic fiber wastewater was pumped into the O-SBR by the third peristaltic pump. The O-SBR was operated for four cycles per day. The effluent ratio was maintained at 40%, and the hydraulic retention time was 7.5 h. Each cycle included 10 min of influent, 180 min of aerobic stirring, 30 min of sedimentation, 10 min of effluent, and 130 min of idling. The sludge concentration was maintained at 2500-3500 mg / L. The aeration rate was controlled at 1.0-1.2 L / min during aerobic stirring. When the ammonia nitrogen removal rate of the O-SBR was greater than 95%, it entered the second stage. Except for the dilution ratio of acrylic fiber wastewater, the operating parameters of the second stage, the third stage, and the fourth stage were the same as those of the first stage. When the ammonia nitrogen removal rate of the O-SBR was greater than 95% in the fourth stage, it entered the next stage. When the ammonia nitrogen in the effluent of the O-SBR was less than 5 mg / L and was stably maintained for more than 15 days, it was considered that the start-up of the full-scale nitrification reactor was successful.

[0011] Dilution ratio = (volume of dilution domestic sewage) / (volume of acrylic fiber wastewater + volume of domestic sewage) * 100%

[0012] Ammonia nitrogen removal rate = (influent ammonia nitrogen concentration - effluent ammonia nitrogen concentration) / (influent ammonia nitrogen concentration) * 100%

[0013] (2) Start-up of PDA-UASB: The granular sludge of short-cut denitrification ANAMMOX was used as the inoculated sludge and was added to the PDA-UASB. The sludge concentration in the reactor was maintained at 15000-20000 mg / L. The temperature in the reactor was controlled by a temperature control device to be 25℃. The hydraulic retention time was 10 h. The fully nitrified acrylic fiber wastewater and domestic sewage were pumped into the PDA-UASB by the second peristaltic pump and the third peristaltic pump, respectively. The c(NO3 - -N) / c(NH4 + -N) = 1.1-1.3, COD / c(NO3 - -N) = 2.5-3.5, and the reflux ratio was 300%-500%. When the total nitrogen in the effluent was less than 15 mg / L, and the ammonia nitrogen was less than 5 mg / L, and was stably maintained for more than 15 days, it was considered that the start-up of the short-cut denitrification coupled ANAMMOX system was successful.

[0014] (3) Late running stage: the acrylic fiber wastewater enters O-SBR, and is operated for 6 cycles per day, the drainage ratio is 40%, the hydraulic retention time is 6.25h, each cycle includes 10min of water inlet, 150min of aerobic stirring, 30min of sedimentation, 5min of water drainage, 45min of idling, the sludge concentration is maintained at 2500-3500mg / L, the aeration amount is controlled at 1.0-1.2L / min during aerobic stirring; the water inlet of PDA-UASB is the mixed wastewater of domestic sewage and completely nitrified acrylic fiber wastewater, c(NO3 - -N) / c(NH4 + -N) = 1.1-1.3, COD / c(NO3 - -N) = 2.5-3.5, the hydraulic retention time is 8h, the sludge retention time is 30d, and the reflux ratio is 300%-500%;

[0015] In order to ensure good running effect and optimize running efficiency, the two reactors are monitored respectively in the late running: if the ammonia nitrogen in the O-SBR effluent is ≥5mg / L, the aeration time is extended by 0.5h every 15 days until the ammonia nitrogen in the effluent is <5mg / L; if the ammonia nitrogen in the O-SBR effluent is <5mg / L for 15 consecutive days, the aeration time is reduced by 0.25h, and the ammonia nitrogen in the effluent is continuously monitored; if the ammonia nitrogen in the PDA-UASB effluent is ≥5mg / L, and the total nitrogen in the effluent is ≥15mg / L, the hydraulic retention time is extended by 1h every 15 days; if the ammonia nitrogen in the PDA-UASB effluent is ≥5mg / L, the hydraulic retention time is extended by 1h every 15 days, and the domestic sewage inlet amount is appropriately reduced until the ammonia nitrogen in the effluent is <5mg / L; if the ammonia nitrogen in the PDA-UASB effluent is <5mg / L, and the total nitrogen in the effluent is ≥15mg / L, the hydraulic retention time is kept unchanged, the domestic sewage inlet amount is increased every 15 days, and under the condition that the ammonia nitrogen in the effluent is <5mg / L, the nitrate nitrogen in the effluent is <10mg / L until the nitrate nitrogen in the effluent is <10mg / L; if the ammonia nitrogen in the PDA-UASB effluent is <5mg / L, and the nitrate nitrogen is <10mg / L for more than 15 days, the hydraulic retention time is shortened by 0.5h.

[0016] The device and method for cooperatively treating acrylic fiber wastewater and domestic sewage by nitrification-short-cut denitrification coupled with anaerobic ammonia oxidation have the following advantages compared with the existing process:

[0017] (1) The organic matter in the domestic sewage is reduced by the short-cut denitrification bacteria as the electron donor to reduce the nitrate nitrogen, the organic matter in the domestic sewage is recycled, the energy consumption caused by carbon removal of the organic matter in the domestic sewage is reduced, the organic matter in the domestic sewage is resourceized, and waste is treated by waste.

[0018] (2) The nutrients of the domestic sewage and the acrylic fiber wastewater are mutually supplemented, and the toxic and harmful substances are mutually diluted, so that a better treatment effect can be achieved.

[0019] (3) While completing the entire nitrification process, the O-SBR also removes toxic and harmful substances in the acrylonitrile wastewater to a certain extent under the action of microorganisms.

[0020] (4) Nitrification-short-cut denitrification coupled with anaerobic ammonium oxidation does not require the addition of external carbon sources, saves aeration energy consumption, and reduces sludge discharge. Attached Figure Description

[0021] Figure 1 A schematic diagram of a device for the synergistic treatment of acrylonitrile wastewater and domestic sewage by nitrification-short-cut denitrification coupled with anaerobic ammonium oxidation.

[0022] Figure 1 In the middle: 1—Acrylic fiber wastewater raw water tank, 2—O-SBR, 3—Acrylic fiber wastewater intermediate water tank, 4—Domestic sewage raw water tank, 5—PDA-UASB, 6—Outlet tank; 2.1—First peristaltic pump, 2.2—First agitator, 2.3—First dissolved oxygen controller, 2.4—Second pH controller, 2.5—Aeration device, 2.6—Gas flow meter, 2.7—First drain valve, 5.1—Second peristaltic pump, 5.2—Third peristaltic pump, 5.3—Fourth peristaltic pump, 5.4—Second dissolved oxygen controller, 5.5—Second pH controller, 5.6—Temperature control device. Detailed Implementation

[0023] The invention will be further described below with reference to the accompanying drawings and embodiments: An apparatus and method for the synergistic treatment of acrylonitrile wastewater and domestic sewage by nitrification-short-cut denitrification coupled with anaerobic ammonium oxidation, characterized in that: it includes a first inlet tank (1), an O-SBR (2), an intermediate tank for acrylonitrile wastewater (3), a second inlet tank (4), a PDA-UASB (5), and an outlet tank (6); the acrylonitrile wastewater enters the O-SBR from the first inlet tank through a first peristaltic pump (2.1), and the O-SBR is equipped with a stirrer (2.2), a first dissolved oxygen controller (2.3), and a first pH controller. The device (2.4), aeration device (2.5) and gas flow meter (2.6) are installed. The fully nitrated acrylonitrile wastewater is discharged into the intermediate tank of acrylonitrile wastewater through the first drain valve (2.7). Domestic sewage is stored in the second inlet tank. The fully nitrated acrylonitrile wastewater and domestic sewage are pumped into the PDA-UASB by the second peristaltic pump (5.1) and the third peristaltic pump (5.2) respectively. The PDA-UASB is equipped with a second dissolved oxygen controller (5.4), a second pH controller (5.5) and a temperature control device (5.6). Part of its effluent is returned to the bottom of the PDA-UASB by the sixth peristaltic pump (5.3) with a return ratio of 300%-500%. The remaining effluent is discharged into the outlet tank.

[0024] The septic tank wastewater and the acrylic fiber production wastewater of a certain factory in Beijing were used as the treatment objects. The specific water quality during the operation was as follows: the COD of the domestic sewage was 180-300 mg / L, the NH4 + -N was 50-80 mg / L, the NO3 - -N was less than or equal to 2 mg / L, the NO2 - -N was less than or equal to 0.5 mg / L; the NH4 + -N of the acrylic fiber wastewater was 80-100 mg / L, the NO3 - -N was less than or equal to 2 mg / L, the NO2 - -N was less than or equal to 0.5 mg / L. The test system was as shown in the figure, the effective volume of the O-SBR was 10 L, the effective volume of the PDA-UASB was 20 L, and both were made of organic glass. Figure 1

[0025] The specific operation was as follows

[0026] The O-SBR was started by inoculating the sludge from the secondary sedimentation tank of a municipal wastewater treatment plant, and the strategy of using the gradient dilution of the acrylic fiber wastewater with the domestic sewage was adopted. The gradient dilution of the acrylic fiber wastewater was divided into four stages according to the dilution ratio (75%, 50%, 25%, 0). In the first stage, the dilution ratio of the acrylic fiber wastewater was 75%, the diluted acrylic fiber wastewater was introduced into the O-SBR through the third peristaltic pump, the drainage ratio was maintained at 40%, the hydraulic retention time was 7.5 h, each cycle included water inlet for 10 min, aerobic stirring for 180 min, sedimentation for 30 min, water outlet for 10 min, and idle for 130 min, the sludge concentration was maintained at 2500-3500 mg / L, the aeration amount was controlled at 1.0-1.2 L / min during the aerobic stirring, and when the ammonia nitrogen removal rate of the O-SBR was greater than 95%, the second stage was entered. Except for the different dilution ratio of the acrylic fiber wastewater, the operation parameters of the second stage, the third stage and the fourth stage were the same as those of the first stage. When the ammonia nitrogen removal rate of the O-SBR was greater than 95% in the fourth stage, the next stage was entered. When the ammonia nitrogen of the O-SBR in the fourth stage was less than 5 mg / L and was stably maintained for more than 15 days, it was considered that the full-scale nitrification reactor was successfully started;

[0027] Dilution ratio = (volume of domestic sewage used for dilution) / (volume of acrylic fiber wastewater + volume of domestic sewage) * 100%

[0028] Ammonia nitrogen removal rate = (influent ammonia nitrogen concentration - effluent ammonia nitrogen concentration) / (influent ammonia nitrogen concentration) * 100%

[0029] ​(2) Start-up of PDA-UASB: The granular sludge with short-cut denitrification and ANAMMOX activity was used as the inoculation sludge to be added into the PDA-UASB, and the sludge concentration in the reactor was maintained at 15000-20000 mg / L, the temperature in the reactor was controlled by the temperature control device to be 25℃, the hydraulic retention time was 10 h, and the acrylic fiber wastewater and domestic wastewater after complete nitrification were respectively pumped into the PDA-UASB by the second peristaltic pump and the third peristaltic pump, so that the mixed water was discharged from the c(NO3 — -N) / c(NH4 + -N) = 1.1-1.3, COD / NO3 - -N = 2.5-3.5, and the reflux ratio was 300%-500%, when the total nitrogen in the effluent was less than 15 mg / L and the ammonia nitrogen was less than 5 mg / L and was stably maintained for more than 15 days, it was considered that the start-up of the short-cut denitrification coupled with ANAMMOX system was successful;

[0030] (3) Late running stage: the acrylic fiber wastewater was introduced into the O-SBR, which was operated for 6 cycles per day, the drainage ratio was 40%, the hydraulic retention time was 6.25 h, each cycle included water inlet for 10 min, aerobic stirring for 150 min, sedimentation for 30 min, water discharge for 5 min, and idle for 45 min, the sludge concentration was maintained at 2500-3500 mg / L, and the aeration amount was controlled at 1.0-1.2 L / min during the aerobic stirring; the water inlet of the PDA-UASB was the mixed wastewater of domestic wastewater and completely nitrified acrylic fiber wastewater c(NO3 - -N) / c(NH4 + -N) = 1.1-1.3, COD / c(NO3 - -N) = 2.5-3.5, the hydraulic retention time was 8 h, the sludge retention time was 30 d, and the reflux ratio was 300%-500%;

[0031] In order to ensure good operation effect and optimize operation efficiency, the two reactors are monitored respectively in the later operation: if the effluent ammonia nitrogen of O-SBR is equal to or greater than 5 mg / L, the aeration time is prolonged by 0.5 h every 15 days until the effluent ammonia nitrogen is less than 5 mg / L; if the effluent ammonia nitrogen of O-SBR is less than 5 mg / L for 15 days, the aeration time is reduced by 0.25 h, and the effluent ammonia nitrogen is continuously monitored; if the effluent ammonia nitrogen of PDA-UASB is equal to or greater than 5 mg / L, and the effluent total nitrogen is equal to or greater than 15 mg / L, the hydraulic retention time is prolonged by 1 h every 15 days; if the effluent ammonia nitrogen of PDA-UASB is equal to or greater than 5 mg / L, the hydraulic retention time is prolonged by 1 h every 15 days, and the influent amount of domestic sewage is appropriately reduced until the effluent ammonia nitrogen is less than 5 mg / L; if the effluent ammonia nitrogen of PDA-UASB is less than 5 mg / L, and the effluent total nitrogen is equal to or greater than 15 mg / L, the hydraulic retention time is kept unchanged, the influent amount of domestic sewage is increased every 15 days, and the effluent ammonia nitrogen is kept less than 5 mg / L until the effluent nitrate nitrogen is less than 10 mg / L; if the effluent ammonia nitrogen of PDA-UASB is less than 5 mg / L, and the effluent nitrate nitrogen is less than 10 mg / L for more than 15 days, the hydraulic retention time is shortened by 0.5 h.

[0032] The test results show that after stable operation, the effluent NH4 + -N is less than 5 mg / L, and the total nitrogen is less than 10 mg / L, the effluent ammonia nitrogen, nitrite, nitrate nitrogen, total nitrogen, SCN - and other technical indexes are all stably reached the wastewater comprehensive discharge standard.

[0033] The above is the specific embodiment of the present application, which is convenient for the technical personnel in the technical field to better understand and apply the present application, and the implementation of the present application is not limited thereto, so that the simple improvement of the present application made by the technical personnel in the technical field is within the scope of the present application.

Claims

1. A method for synergistic treatment of acrylonitrile wastewater and domestic sewage by nitrification-short-cut denitrification coupled with anaerobic ammonium oxidation, the apparatus of which includes a first inlet tank (1), a full-process nitrification sequencing batch reactor (O-SBR) (2), an intermediate tank for acrylonitrile wastewater (3), a second inlet tank (4), a short-cut denitrification coupled with anaerobic ammonium oxidation upflow anaerobic sludge blanket reactor (PDA-UASB) (5), and an outlet tank (6); the acrylonitrile wastewater enters the O-SBR from the first inlet tank through a first peristaltic pump (2.1), the O-SBR is equipped with a stirrer (2.2), a first dissolved oxygen controller (2.3), a first pH controller (2.4), and an aeration device. (2.5) and gas flow meter (2.6), the fully nitrated acrylonitrile wastewater is discharged into the intermediate tank of acrylonitrile wastewater through the first drain valve (2.7); domestic sewage is stored in the second inlet tank. The fully nitrated acrylonitrile wastewater and domestic sewage are pumped into the PDA-UASB by the second peristaltic pump (5.1) and the third peristaltic pump (5.2) respectively. The PDA-UASB is equipped with a second dissolved oxygen controller (5.4), a second pH controller (5.5) and a temperature control device (5.6). Part of its effluent is returned to the bottom of the PDA-UASB through the sixth peristaltic pump (5.3), with a return ratio of 300%-500%. The remaining effluent is discharged into the outlet tank. Its features are, Includes the following steps: (1) Start-up of O-SBR: The inoculated sludge was residual sludge from the secondary sedimentation tank of the municipal wastewater treatment plant. A strategy of gradient dilution of acrylonitrile wastewater with domestic sewage was adopted as the influent. The acrylonitrile wastewater was gradient diluted in four stages according to the dilution ratios of 75%, 50%, 25%, and 0. In the first stage, the acrylonitrile wastewater dilution ratio was 75%. The diluted acrylonitrile wastewater was introduced into the O-SBR through a third peristaltic pump. The O-SBR was run for four cycles per day, with the discharge ratio maintained at 40% and the hydraulic retention time at 7.5 hours. Each cycle included 10 minutes of influent, 180 minutes of aerobic stirring, 30 minutes of sedimentation, and discharge. Water is introduced for 10 minutes, then left idle for 130 minutes. The sludge concentration is maintained at 2500-3500 mg / L. During aerobic stirring, the aeration rate is controlled at 1.0-1.2 L / min. Once the O-SBR ammonia nitrogen removal rate is greater than 95%, the second stage begins. Except for the different dilution ratio of acrylonitrile wastewater, the operating parameters for the second, third, and fourth stages are the same as those for the first stage. When the O-SBR ammonia nitrogen removal rate is greater than 95% in a particular stage, the next stage begins. When the ammonia nitrogen in the O-SBR effluent of the fourth stage is less than 5 mg / L and remains stable for more than 15 days, the entire nitrification reactor can be considered to have started up successfully. Dilution ratio = (Volume of domestic sewage used for dilution) / (Volume of acrylic fiber wastewater + Volume of domestic sewage) * 100% Ammonia nitrogen removal rate = (Influent ammonia nitrogen concentration - Effluent ammonia nitrogen concentration) / (Influent ammonia nitrogen concentration) * 100% (2) Start-up of PDA-UASB: Short-cut denitrification anaerobic ammonium oxidation granular sludge was added to the PDA-UASB as inoculum sludge, maintaining the sludge concentration in the reactor at 15000-20000 mg / L. The reactor temperature was controlled at 25℃ by a temperature control device, and the hydraulic retention time was 10 h. The fully nitrified acrylonitrile wastewater and domestic sewage were pumped into the PDA-UASB by the second and third peristaltic pumps, respectively, to mix the influent and increase the concentration of NO3-. - -N) / c(NH4 + -N)=1.1-1.3, COD / c(NO3) - -N)=2.5-3.5, reflux ratio is 300%-500%, and when the total nitrogen in the effluent is less than 15mg / L and the ammonia nitrogen is less than 5mg / L, and is maintained stably for more than 15 days, the short-cut denitrification coupled anaerobic ammonia oxidation system can be considered to have been successfully started. (3) Later operation stage: Acrylic fiber wastewater enters the O-SBR, which operates for 6 cycles per day, with a discharge ratio of 40% and a hydraulic retention time of 6.25h. Each cycle includes 10min of influent, 150min of aerobic stirring, 30min of sedimentation, 5min of discharge, and 45min of idle time. The sludge concentration is maintained at 2500-3500mg / L, and the aeration rate during aerobic stirring is controlled at 1.0-1.2L / min. The influent of the PDA-UASB is a mixture of domestic sewage and fully nitrated acrylic fiber wastewater, with c(NO3) - -N) / c(NH4 + -N)=1.1-1.3, COD / c(NO3) - -N)=2.5-3.5, hydraulic retention time 8h, sludge retention time 30d, reflux ratio 300%-500%; The two reactors were monitored separately: If the ammonia nitrogen in the O-SBR effluent was ≥5 mg / L, the aeration time was extended by 0.5 h every 15 days until the ammonia nitrogen in the effluent was <5 mg / L; if the ammonia nitrogen in the O-SBR effluent remained <5 mg / L for 15 consecutive days, the aeration time was reduced by 0.25 h, and the ammonia nitrogen in the effluent was monitored again; if the ammonia nitrogen in the PDA-UASB effluent was ≥5 mg / L and the total nitrogen in the effluent was ≥15 mg / L, the hydraulic retention time was extended by 1 h every 15 days; if the ammonia nitrogen in the PDA-UASB effluent was ≥5 mg / L, the aeration time was extended by 1 h every 15 days. Extend the hydraulic retention time by 1 hour and simultaneously reduce the influent flow rate of domestic sewage until the effluent ammonia nitrogen is <5 mg / L; if the effluent ammonia nitrogen of PDA-UASB is <5 mg / L and the effluent total nitrogen is ≥15 mg / L, then keep the hydraulic retention time unchanged and increase the influent flow rate of domestic sewage every 15 days until the effluent nitrate nitrogen is <10 mg / L, while maintaining the effluent ammonia nitrogen <5 mg / L; if the effluent ammonia nitrogen of PDA-UASB is <5 mg / L and the effluent nitrate nitrogen is <10 mg / L for more than 15 days, then shorten the hydraulic retention time by 0.5 hours.

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