CN111422983A - A short-path nitrification-anammox two-stage sewage treatment device and process - Google Patents

Abstract

The invention discloses a short-path nitrification-anammox two-stage sewage treatment device, comprising three parts: a chemically intensified primary treatment reaction device, a short-path nitrification MBBR reactor and an anammox UASB reactor; The urban domestic sewage is treated in a chemically intensified primary treatment system to remove most of the organic matter and total phosphorus, and then stable short-range nitrification is carried out through the MBBR reactor controlled by the automatic control system to convert about 50% of NH ₄ ⁺ ‑N into NO. ₂ ^-- N, remove most of the organic matter in the sewage at the same time, and then go through the anammox UASB reactor for anammox reaction, and use NO ₂ ^-- N as an electron acceptor to convert NH under the action of anammox bacteria. ₄ ⁺ ‑N is converted into nitrogen to achieve the purpose of deep denitrification. The two-stage sewage treatment device and process provided by the invention can save a lot of energy in the whole process flow, realize efficient denitrification of urban domestic sewage, and provide a low-consumption and effective process mode for urban domestic sewage treatment.

Description

A short-path nitrification-anammox two-stage sewage treatment device and process

technical field

The invention relates to a short-range nitrification-anaerobic ammonia oxidation two-stage sewage treatment device and process, belongs to the technical field of sewage treatment, and is suitable for the mainstream treatment system of urban domestic sewage.

Background technique

With the continuous improvement of the speed of urban development in my country, the problem of water pollution caused by the substandard discharge of urban domestic sewage continues to intensify. The nitrification-denitrification biological denitrification process used in the traditional urban domestic sewage treatment process needs to add a large amount of carbon sources, which has disadvantages such as high energy consumption and inconvenient operation, and it is difficult to fully meet the development needs of a resource-saving society. The new biological denitrification technology represented by oxyammonium oxidation has become a research hotspot in the field of international water treatment. Anammox is the use of anammox bacteria to convert ammonia nitrogen (NH ₄ ⁺ -N) into nitrogen gas using CO ₂ as a carbon source and nitrite (NO ₂ ^- -N) as an electron acceptor under anoxic conditions. (N ₂ ). There is almost no NO ₂ ^- -N in urban domestic sewage, so the application of anammox to urban domestic sewage treatment must find a way to obtain NO ₂ ^- -N stably. The commonly used method to obtain stable NO ₂ ^- -N is to use short-range nitrification, that is, using the difference in the physiological characteristics of ammonia-oxidizing bacteria (Ammonia-oxidizing Bacteria, AOB) and nitrite-oxidizing bacteria (Nitrite-oxidizing Bacteria, NOB), combined with The reaction conditions are controlled to promote the growth of AOB and inhibit the growth of NOB, oxidize about 50%~60% of NH ₄ ⁺ -N in wastewater to NO ₂ ^- -N, and prevent further oxidation of NO ₂ ^- -N. However, due to the characteristics of low water temperature, large water volume, strong water quality fluctuation, and low ammonia nitrogen concentration in urban domestic sewage, it is difficult to provide free ammonia concentration that can effectively inhibit the activity of NOB, which often makes NOB in the competition with AOB. Short-range nitrification. Therefore, the stable control of short-range nitrification has become the main bottleneck for incorporating the anammox process into the mainstream treatment system of urban domestic sewage. In addition, a certain amount of organic matter in urban domestic sewage will inhibit anammox bacteria, and this factor also limits the application of anammox process in urban domestic sewage treatment.

In the study of the control strategies of AOB and NOB nitrifying bacteria in the short-range nitrification process, the researchers found that compared with NOB, AOB has more affinity for O ₂ , which can reduce the use of O ₂ by NOB by limiting DO. , thereby inhibiting its further oxidation of NO ₂ ^- -N, where the degree of DO limitation is often assessed according to the value of DO/NH ₄ ⁺ -N. Studies have shown that this control method can achieve good results when the DO/NH ₄ ⁺ -N is lower than 0.1 in the short-range nitrification of synthetic ammonia nitrogen wastewater without organic carbon, but we will use the same control conditions for urban domestic sewage. , although nitrification of nearly 60% of ammonia nitrogen was observed, but no accumulation of NO ₂ ^- -N was observed.

SUMMARY OF THE INVENTION

Objective: In order to overcome the problems that short-range nitrification is difficult to stably control in the process of incorporating anammox technology into the mainstream treatment process of urban domestic sewage and the excessive organic content of urban domestic sewage inhibits anammox reaction, the present invention provides a short-range nitrification method. -Anaerobic ammonia oxidation two-stage sewage treatment device and process, the entire process can save a lot of energy, realize efficient denitrification of urban domestic sewage, and provide a low-consumption and effective process mode for urban domestic sewage treatment.

Some studies have shown that controlling the concentration of free ammonia (FA) can obtain a certain NOB inhibitory effect. According to the effect of pH on free ammonia, when the pH increases, ammonia nitrogen in water will be converted into free ammonia, and the short-range nitrification of urban biological sewage will not be effective. During the process, the pH will continue to drop, so we can obtain an appropriate amount of free ammonia concentration through pH control to inhibit the activity of NOB.

Moving Bed Biofilm Reactor (MBBR) combines the advantages of activated sludge method and biofilm method, in which the added suspended carrier can form the conditions of internal growth of anaerobic bacteria and external attachment of aerobic bacteria. Under the action of aeration and water flow, the oxygen utilization efficiency is greatly improved, the removal effect of organic matter is improved, and conditions are also provided for the realization of stable short-range nitrification. The three-phase separator in the Up-flow Anaerobic SludgeBlanket Reactor (UASB) has an efficient interception effect on anammox bacteria, which can greatly improve the conversion rate of anammox reaction .

Based on this, the present invention adopts the series combination of short-path nitrification MBBR reactor and anammox UASB reactor, wherein a chemically enhanced primary treatment reaction device is set before the short-path nitrification MBBR reactor to reduce the burden of subsequent biological treatment; The ₄ ⁺ -N automatic control system and the pH automatic control system control the reaction conditions required for short-range nitrification to achieve stable short-range nitrification. The optimal range of control parameters is determined through parameter debugging experiments; finally, the anaerobic ammonia oxidation UASB reactor is used to achieve deep dehydration. nitrogen.

Technical scheme: in order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

A short-path nitrification-anammox two-stage sewage treatment device, comprising a chemically enhanced primary treatment reaction tank, a sedimentation tank, a short-path nitrification MBBR reactor, a sedimentation device, an intermediate water tank and an anammox UASB reactor;

The chemically enhanced primary treatment reaction tank is connected with a sedimentation tank, a coagulant dosing device is arranged above the chemically enhanced primary treatment reaction tank, and a sludge discharge port is arranged below the sedimentation tank;

The sedimentation tank is connected with the short-path nitrification MBBR reactor through the first inlet pump, and the outlet pipe of the short-path nitrification MBBR reactor is connected with the sedimentation device; the short-path nitrification MBBR reactor is provided with a microporous aeration device at the bottom, and the short-path nitrification MBBR reactor is The MBBR reactor is also provided with a short-range nitrification automatic control system; a sludge discharge pump is provided below the sedimentation device;

The water outlet pipe of the sedimentation device is connected with the intermediate water tank; the intermediate water tank is connected with the anammox UASB reactor through the second inlet pump, and a reflux pump is arranged on one side of the anammox UASB reactor for internal circulation of sludge.

Further, the inside of the microporous aeration device is filled with a cylindrical HDPE filler carrier, and the filling rate is 40%.

Further, the short-range nitrification automatic control system includes a DO/NH ₄ ⁺ -N automatic control system and a pH automatic control system.

Further, the DO/NH ₄ ⁺ -N automatic control system is composed of a programmable logic controller, an ammonia nitrogen sensor, a dissolved oxygen sensor, and an air pump, and the air pump is connected with a microporous aeration device; the ammonia nitrogen sensor, The dissolved oxygen sensor is connected to the input end of the programmable logic controller, and the output end of the programmable logic controller is connected to the air pump; the pH automatic control system includes a programmable logic controller, a pH sensor, and an alkali adding device, and the pH The sensor is connected with the input end of the programmable logic controller, the alkali adding device is connected with the output end of the programmable logic controller; the programmable logic control of the DO/NH ₄ ⁺ -N automatic control system and the pH automatic control system device is the same.

Further, a three-phase separator and a water outlet are provided above the anammox UASB reactor, and a sampling port is provided on the side.

A short-range nitrification-anammox two-stage sewage treatment process is carried out by utilizing the aforementioned device, and specifically includes the following processes:

1) The urban domestic sewage is treated by chemically intensified primary treatment reaction tank and sedimentation tank to remove most of the suspended solids, total phosphorus and organic matter, and then enters the short-range nitrification MBBR reactor. By adjusting the first inlet pump, the reaction time is controlled 8- For 10h, adopt the control conditions of DO/NH ₄ ⁺ -N automatic control and pH automatic control, real-time online monitoring through dissolved oxygen sensor and ammonia nitrogen sensor, and control the microporous aeration device. DO/NH ₄ ⁺ -N was controlled in the range of 0.08 + 0.02, and real-time online monitoring was performed by pH sensor. The pH in the short-path nitrification MBBR reactor was controlled within the range of 8.5-8.9 by the alkali addition device to achieve stable short-path nitrification. About 50% of the NH ₄ ⁺ -N in the influent is converted into NO ₂ ^- -N, and the NH ₄ ⁺ -N/NO ₂ ^- -N in the effluent is close to 1:1 during stable operation;

2) The sewage treated by the short-range nitrification MBBR reactor is separated from the sludge by the sedimentation device, and the excess sludge is discharged through the sludge discharge pump. The upper effluent of the sedimentation device enters the intermediate water tank, and is pumped into the anaerobic ammonia oxidation UASB reactor through the second inlet pump. , under anoxic conditions, the anaerobic ammonia oxidation bacteria use NO ₂ ^- -N as the electron acceptor to convert NH ₄ ⁺ -N into nitrogen, further reducing the total nitrogen, and the internal circulation of the sludge through the internal return pump, the reaction time By adjusting the pump speed of the second inlet pump, the pump speed is controlled to be about 8h, and the effluent is discharged through the water outlet.

Beneficial effects: The short-range nitrification-anammox two-stage sewage treatment device and process provided by the present invention have the following advantages compared with the prior art:

1) The short-range nitrification MBBR reactor is controlled by DO/NH ₄ ⁺ -N and pH with real-time online detection and automatic control system, the aeration rate is adjusted according to the ammonia nitrogen concentration in the influent, the pH is controlled to increase the free ammonia concentration, and NOB is well inhibited The activity of nitrification can achieve stable short-range nitrification and provide a stable substrate for subsequent anammox;

2) The anammox UASB reactor has a three-phase separator and an internal return device, which can achieve efficient retention of anammox bacteria, maintain the concentration of anammox bacteria in the reactor at a high level, and effectively improve anammox. Conversion rate;

3) The short-path nitrification-anammox two-stage process is used to separate the two reaction processes of short-path nitrification and anammox, which avoids the bad competition between the dominant bacteria in the two reaction processes, and is removed by the short-path nitrification MBBR reactor. Most of the organic matter in the sewage also provides a good living environment for anammox bacteria, which greatly improves the efficiency of anammox.

Description of drawings

FIG. 1 is a schematic structural diagram of a short-path nitrification-anammox two-stage sewage treatment device provided by the present invention.

Reference numerals: 1. Chemically enhanced primary treatment reaction tank, 11. Water inlet, 12. Coagulant dosing device, 2. Sedimentation tank, 21. First inlet pump, 22. Sludge outlet, 3. Short-path nitrification MBBR reactor, 31. Microporous aeration device, 32. Programmable logic controller, 33. Ammonia nitrogen sensor, 34. pH sensor, 35. Dissolved oxygen sensor, 36. Alkali addition device, 37. Air pump, 4. Precipitation device, 41. Sludge pump, 5. Intermediate water tank, 51. Second inlet pump, 6. Anammox UASB reactor, 61. Three-phase separator, 62. Reflux pump, 63. Sampling port, 64. Outlet water outlet.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

A short-path nitrification-anammox two-stage sewage treatment device, comprising a chemically enhanced primary treatment reaction tank 1, a sedimentation tank 2, a short-path nitrification MBBR reactor 3, a sedimentation device 4, an intermediate water tank 5 and an anammox UASB reaction device 6. The chemically enhanced primary treatment reaction tank 1 is connected to the sedimentation tank 2, a water inlet 11 is arranged on one side of the chemically enhanced primary treatment reaction tank 1, and a coagulant doser 12 is arranged above the chemically enhanced primary treatment reaction tank 1 , the coagulant is added into the chemically strengthened primary treatment reaction tank 1 through the coagulant dosing device 12, and the sludge discharge port 22 is arranged under the sedimentation tank 2, and the sludge in the sedimentation tank 2 is discharged through the sludge discharge port 22. .

The sedimentation tank 2 is connected with the short-path nitrification MBBR reactor 3 through the first inlet water pump 21. The short-path nitrification MBBR reactor 3 is provided with a microporous aeration device 31 at the bottom, and the microporous aeration device 31 is filled with cylindrical HDPE. The filler carrier has a specific surface area of 400 m ² /m ³ and a filling rate of 40%. The short-path nitrification MBBR reactor 3 is also provided with a short-path nitrification automatic control system, and the short-path nitrification automatic control system includes a DO/NH ₄ ⁺ -N automatic control system and a pH automatic control system. The DO/NH ₄ ⁺ -N automatic control system is composed of a programmable logic controller (PLC) 32 , an ammonia nitrogen sensor 33 , a dissolved oxygen sensor 35 , and an air pump 37 , and the air pump 37 is connected to the microporous aeration device 31 The ammonia nitrogen sensor 33 and the dissolved oxygen sensor 35 are connected to the input end of the programmable logic controller (PLC) 32, and the ammonia nitrogen concentration and dissolved oxygen value monitored in real time are transmitted to the PLC. The programmable logic controller (PLC) 32 The output end is connected with the air pump 37, so as to control the microporous aeration device 31 to ensure that the value of DO/NH ₄ ⁺ -N in the short-path nitrification MBBR reactor is in the optimal range; the pH automatic control system includes programmable logic A controller (PLC) 32, a pH sensor 34, and an alkali adding device 36, the pH sensor 34 is connected to the input end of the programmable logic controller (PLC) 32, and transmits the pH value monitored in real time to the PLC, and the The alkali adding device 36 is connected with the output end of the programmable logic controller (PLC) 32, and the PLC controls the alkali adding device to control the pH value in the short-range nitrification MBBR reactor 3 to be in the optimal range; the DO/NH ₄ ⁺ -N automatically The programmable logic controller 32 of the control system and the pH automatic control system is the same.

The outlet pipe of the short-range nitrification MBBR reactor 3 is connected with the sedimentation device 4 , and a sludge discharge pump 41 is arranged below the sedimentation device 4 ; the outlet pipe of the sedimentation device 4 is connected with the intermediate water tank 5 . The intermediate water tank 5 is connected with the anammox UASB reactor 6 through the second inlet water pump 51, and one side of the anammox UASB reactor 6 is provided with a return pump for internal circulation of sludge; A three-phase separator 61 and a water outlet 64 are provided above the UASB reactor 6, and a sampling port 63 is provided on the side.

Example of sewage treatment:

The test water was taken from an urban domestic sewage treatment plant after primary treatment, and its water quality is as follows: COD concentration is 100 mg/L ~ 150 mg/L, TN concentration is 40 mg/L ~ 50 mg/L, TP concentration is 4 ~6 mg/L. The experiment adopts the reaction device shown in Figure 1. The effective volume of the short-path nitrification MBBR reactor is 50L, and the effective volume of the anammox UASB reactor is 20L. The materials used in both are plexiglass.

The specific operation process is as follows:

Start-up stage: The short-range nitrification MBBR reactor 3 is started with the membrane backflow sludge from the nitrification reactor of the sewage treatment plant, so that the sludge concentration in the reactor is 3000~4000mg/L, the dissolved oxygen is controlled to 3~5mg/L, and the hydraulic pressure The residence time is about 12h, and the detection rate of ammonia nitrogen removal in water reaches more than 60%, indicating that the short-path nitrification MBBR reactor is successfully started. Anammox UASB reactor 6 was inoculated with anammox granular sludge, and the DO concentration was controlled to be close to 0 mg/L. The anammox granular sludge was cultured and domesticated by using the NH ₄ ⁺ -N/NO ₂ ^- -N matrix solution prepared in the laboratory, and the TN removal rate in the effluent reached about 70%, indicating the UASB reaction of anammox. The debugging of the device was successful.

Parameter debugging: Determine the control parameters of the short-path nitrification MBBR reactor 3 that has been successfully started with the film. When DO/NH ₄ ⁺ -N is set to about 0.08, the ammonia nitrogen removal rate in the effluent of the short-path nitrification MBBR reactor will reach 0.08 after running for a period of time. 50%~60%, but the NO ₂ ^- -N content in the effluent is very low, so we controlled other parameters to remain unchanged and increased the pH value in the reactor. The NO ₂ ^- -N in the effluent increased significantly, and when the pH value increased to 8.5 At ~8.9, the NH ₄ ⁺ -N/NO ₂ ^- -N in the effluent was close to 1:1, achieving stable short-range nitrification.

Operation stage: After the system is debugged and operated stably, the urban domestic sewage is first treated by chemically enhanced primary treatment reaction tank 1, and an appropriate amount of coagulant is added through the coagulant dosing device 12, and then a large amount of suspended solids are coagulated and precipitated through the sedimentation tank 2. , total phosphorus and organic matter, the effluent enters the short-range nitrification MBBR reactor 3, by monitoring the ammonia nitrogen and dissolved oxygen concentration in the reactor in real time and transmitting the values to the PLC, the PLC controls the air pump to control the aeration volume of the microporous aeration device. The DO/NH ₄ ⁺ -N ratio was kept within the optimal range of 0.08 + 0.02 for short-path nitrification. By monitoring the pH value in the reactor in real time and transmitting the value to the PLC, the PLC controlled the alkali adding device to maintain the pH value within the optimal range of short-path nitrification. Within the range of 8.5~8.9, the short _- range nitrification automatic control system controls the reaction conditions to the conditions required for short ^- range nitrification, and the reaction time is ₈ ^~ 10h. The effluent enters the sedimentation device 4 , and the excess sludge is discharged through the sludge discharge pump 41 below the sedimentation device 4 , and the effluent from the upper layer enters the intermediate water tank 5 . The water in the intermediate water tank is pumped into the anaerobic ammonia oxidation UASB reactor 6 through the second outlet pump 51, and the reactor is under anoxic conditions, and the anammox bacteria use NO ₂ ⁻ -N in the wastewater as an electron acceptor to convert NH ₄ ⁺ -N is converted into N ₂ , and the total nitrogen is further reduced. The reaction time is 8h. After the reaction, it passes through the three-phase separator 61 at the upper end of the anammox UASB reactor. The sludge is circulated inside, and the effluent is discharged through the water outlet 64 .

The test results show that the system operates stably, the effluent COD is 30-40 mg/L, the NH ₄ ⁺ -N concentration is 2.5-3.5 mg/L, the NO ₃ ^- -N concentration is 2-4 mg/L, and the TN is less than 12 mg/L. L and TP are lower than 0.5mg/L, the denitrification effect is stable, and the water quality after treatment reaches the Class A standard of "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB 18918-2002).

The device and method for stable short-range nitrification-anammox two-stage treatment of urban domestic sewage provided by the invention can effectively overcome the problem of applying anammox to the mainstream treatment system of urban domestic sewage. The field of nitrogen has good development and application prospects.

The above is only the preferred embodiment of the present invention, it should be pointed out: for those skilled in the art, under the premise of not departing from the principle of the present invention, several improvements and modifications can also be made, and these improvements and modifications are also It should be regarded as the protection scope of the present invention.

Claims (6)

1. A short-path nitrification-anammox two-stage sewage treatment device, characterized in that: it comprises a chemically strengthened primary treatment reaction tank (1), a sedimentation tank (2), a short-path nitrification MBBR reactor (3), a sedimentation device (4), the intermediate water tank (5) and the anammox UASB reactor (6); The chemically enhanced primary treatment reaction tank (1) is connected to a sedimentation tank (2), a coagulant dosing device (12) is arranged above the chemically enhanced primary treatment reaction tank (1), and the sedimentation tank (2) ) below the mud discharge port (22); The sedimentation tank (2) is connected with the short-path nitrification MBBR reactor (3) through the first inlet water pump (21), and the outlet pipe of the short-path nitrification MBBR reactor (3) is connected with the sedimentation device (4); the short-path nitrification MBBR A microporous aeration device (31) is provided at the bottom of the reactor (3), and the short-path nitrification MBBR reactor (3) is also provided with a short-path nitrification automatic control system; a sludge discharge pump (41) is arranged below the sedimentation device (4). ); The water outlet pipe of the sedimentation device (4) is connected with the intermediate water tank (5); the intermediate water tank (5) is connected with the anaerobic ammonium oxidation UASB reactor (6) through the second inlet water pump (51), and the anaerobic ammonium oxidation UASB reactor (6) A reflux pump (62) is provided on one side of the UASB reactor (6) for internal circulation of the sludge. 2. The short-path nitrification-anammox two-stage sewage treatment device according to claim 1, wherein the microporous aeration device (31) is filled with a cylindrical HDPE filler carrier, and the filling rate is 40 %. 3. The short-range nitrification-anammox two-stage sewage treatment device according to claim 1, wherein the short-range nitrification automatic control system comprises a DO/NH ₄ ⁺ -N automatic control system and an automatic pH control system system. 4. A short-range nitrification-anammox two-stage sewage treatment device according to claim 3, characterized in that: the DO/NH ₄ ⁺ -N automatic control system is composed of a programmable logic controller (32), An ammonia nitrogen sensor (33), a dissolved oxygen sensor (35), and an air pump (37), the air pump (37) is connected to the microporous aeration device (31); the ammonia nitrogen sensor (33), the dissolved oxygen sensor (37) 35) is connected to the input end of the programmable logic controller (32), and the output end of the programmable logic controller (32) is connected to the air pump (37); the pH automatic control system includes the programmable logic controller (32) , a pH sensor (34), an alkali adding device (36), the pH sensor (34) is connected to the input end of the programmable logic controller (32), and the alkali adding device (36) is connected to the programmable logic controller ( 32) is connected to the output end; the programmable logic controller (32) of the DO/NH ₄ ⁺ -N automatic control system and the pH automatic control system are the same. 5. A short-path nitrification-anammox two-stage sewage treatment device according to claim 1, characterized in that: a three-phase separator (61) and a three-phase separator (61) and a three-phase separator (61) and The water outlet (64) is provided with a sampling port (63) on the side. 6. A short-range nitrification-anammox two-stage sewage treatment process, characterized in that: utilizing the device described in any one of claims 1-5 to carry out, specifically comprising the following process: 1) The urban domestic sewage is treated by chemically intensified primary treatment reaction tank (1) and sedimentation tank (2) to remove most of the suspended solids, total phosphorus and organic matter, and then enters the short-path nitrification MBBR reactor (3). An inlet water pump (21), the control reaction time is 8-10h, the control conditions combining DO/NH ₄ ⁺ -N automatic control and pH automatic control are adopted, and real-time online monitoring is performed by the dissolved oxygen sensor (35) and the ammonia nitrogen sensor (33). , through the control of the microporous aeration device (31), the DO/NH ₄ ⁺ -N in the short-path nitrification MBBR reactor (3) is controlled within the range of 0.08 + 0.02, and the pH sensor (34) is used for real-time on-line monitoring, through The alkali adding device (36) controls the pH in the short-path nitrification MBBR reactor (3) within the range of 8.5-8.9, realizes stable short-path nitrification, and converts about 50% of the influent NH ₄ ⁺ -N into NO ₂ ^- - N, in the process of stable operation, NH ₄ ⁺ -N/NO ₂ ^- -N in the effluent is close to 1:1; 2) The sewage treated by the short-range nitrification MBBR reactor is separated from the sludge by the sedimentation device (4), the excess sludge is discharged through the sludge discharge pump (41), and the upper effluent of the sedimentation device (4) enters the intermediate water tank (5), and passes through the The second inlet water pump (51) is pumped into the anammox UASB reactor (6), and under anoxic conditions, the anammox bacteria use NO ₂ ^- -N as the electron acceptor to convert NH ₄ ⁺ -N into nitrogen gas , to further reduce the total nitrogen, through the internal return pump (63) to carry out the internal circulation of the sludge, the reaction time is controlled to about 8h by adjusting the pump speed of the second inlet pump (51), and the effluent is discharged through the water outlet (64).

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