JP4556532B2 - Method and apparatus for treating nitric acid waste liquid - Google Patents

Description

  The present invention relates to a method and apparatus for decomposing nitric acid waste liquid discharged from a semiconductor manufacturing factory or the like.

  As a biodegradation method by microbial treatment, in order to carry out denitrogenation reaction by conventional wastewater treatment, a tank in which an anaerobic and aerobic environment is formed is provided separately, and the anaerobic tank is represented by methanol, which is a nutrient salt. A method of continuously adding a hydrogen donor of a denitrifying bacterium for performing a denitrification reaction has been widely used.

  In this method, since an anaerobic and aerobic environment tank is separately provided, an aerobic environment is created to prevent an increase in biochemical oxygen demand (hereinafter referred to as BOD) due to residual methanol. Aeration equipment is required, resulting in an increase in size and complexity of the apparatus and high operating costs. Further, there is a problem that processing efficiency is low and maintenance is very difficult.

  As a means for solving this problem, there is one disclosed in Japanese Patent No. 3298562.

That is, a carrier mainly composed of cellulose, polyvinyl alcohol, or polyethylene glycol is supported on a denitrification accelerator mainly composed of a linear saturated monocarboxylic acid having 6 or more carbon atoms. Is formed into particles, plates, or rods and mounted in an anaerobic tank in an anaerobic environment. (For example, see Patent Document 1)
Japanese Patent No. 3298562

  However, in the method using the denitrification accelerator mainly composed of a linear saturated monocarboxylic acid having 6 or more carbon atoms, the linear saturated monocarboxylic acid is supported on a carrier, It is formed into a particle shape, a plate shape or a rod shape, but as a matter of fact, an organic component such as stearic acid, phosphorus or hydrogen is contained in the carrier.

  As a result, the organic component is dissolved in the nitric acid waste liquid that is the waste liquid to be treated in the anaerobic tank, which leads to an increase in BOD and cannot be discharged as treated water as it is.

  In addition, aeration equipment that creates an aerobic environment is required to prevent an increase in BOD, resulting in increased size and complexity of the apparatus, high operating costs, and difficult maintenance.

  The present invention solves the above-mentioned conventional problems, and does not require an aerobic tank equipped with aeration equipment for creating an aerobic environment, and the denitrification reaction of nitric acid waste liquid and anaerobic reaction in a single anaerobic tank. An object of the present invention is to provide a nitric acid waste liquid treatment method and treatment apparatus that simultaneously prevent the increase in BOD due to the activation of sex microorganisms, reduce the size of the apparatus, and suppress the operation cost.

  In order to solve the above-described conventional problems, the present invention supplies a certain amount of nitric acid waste liquid from the flow rate adjustment tank to the anaerobic tank, forms a circulation flow in the nitric acid waste liquid stored in the anaerobic tank, and circulates the nitric acid waste liquid. A solid nutrient salt mainly composed of a carboxylic acid having 6 or more carbon atoms is supplied to promote the denitrification reaction, and a filtration member carrying anaerobic microorganisms is positioned in the circulating flow of the nitric acid waste liquid. Thus, a nitric acid waste liquid treatment method and treatment apparatus for decomposing an organic component contained in the solid nutrient salt and sucking treated water from the filter member are provided.

  As described above, according to the nitric acid waste liquid treatment method and treatment apparatus of the present invention, the nitric acid waste liquid can be removed in a single anaerobic tank without the need for an aerobic tank equipped with an aeration facility that creates an aerobic environment. The nitrogen reaction and the prevention of BOD increase due to the activation of anaerobic microorganisms can be simultaneously performed, and the apparatus can be downsized and the operating cost can be suppressed.

  In the first invention, a certain amount of nitric acid waste liquid is supplied from the flow rate adjustment tank to the anaerobic tank, a circulation flow is formed in the nitric acid waste liquid stored in the anaerobic tank, and the number of carbon atoms in the circulation flow of the nitric acid waste liquid is 6 or more. A solid nutrient salt mainly composed of carboxylic acid is promoted to promote a denitrification reaction, and a filtration member carrying anaerobic microorganisms is positioned in the circulation flow of the nitric acid waste liquid, This is a method for treating a nitric acid waste liquid by decomposing an organic component contained therein and sucking treated water from the filter member.

  This eliminates the need for an aerobic tank equipped with an aerobic environment that creates an aerobic environment, and prevents a rise in BOD due to denitrification of nitric acid waste liquid and activation of anaerobic microorganisms in a single anaerobic tank. At the same time, it is possible to reduce the size and operating cost of the apparatus.

  According to a second invention, in the method for treating nitric acid waste liquid of the first invention, a downward flow area portion of the nitric acid waste liquid is formed in a central portion in the anaerobic tank, and an upward flow area portion is formed outside the downward flow area portion. A method for treating a nitric acid waste liquid is characterized in that a filtration member is positioned in an upstream region of the nitric acid waste liquid.

  Accordingly, the nitric acid waste liquid flowing along the surface of the filter member hardly deposits a solid component or the like on the surface of the filter member, and a cake layer or the like is not easily formed.

  Further, even if a cake layer or the like is formed, the cake layer or the like is not easily compressed, and the flow rate of treated water to the upstream portion is high, so that a path for water to flow is formed. For this reason, clogging hardly occurs, and a decrease in filtration performance can be suppressed.

  The third invention is a nitric acid waste liquid treatment method according to the second invention, characterized in that the nitric acid waste liquid in the flow rate adjusting tank is supplied to the downward flow area in the anaerobic tank. is there.

  As a result, the newly supplied nitric acid waste liquid is uniformly mixed with the already circulating nitric acid waste liquid in the downflow area and flows into the upflow area, so that it is possible to eliminate the presence of nitric acid waste liquids having different treatment conditions.

  According to a fourth aspect of the present invention, there is provided a method for treating nitric acid waste liquid according to the method for treating nitric acid waste liquid of the second or third aspect of the invention, characterized in that solid nutrient salts are supplied to a downward flow area in an anaerobic tank.

  As a result, the added solid nutrient salts are uniformly diffused by the circulation flow of the nitric acid waste liquid without being partly retained in the nitric acid waste liquid, so that the carboxylic acid can be uniformly dissolved in the nitric acid waste liquid.

  According to a fifth invention, in the method for treating nitric acid waste liquid according to any one of the first to fourth inventions, the nitric acid waste liquid from the flow rate adjusting tank to the anaerobic tank is detected based on the detected value of the oxidation-reduction potential of the nitric acid waste liquid in the anaerobic tank. The nitric acid waste liquid treatment method is characterized in that the supply amount of water or the suction amount of treated water that has passed through the filter member is adjusted.

  As a result, it is possible to discharge the treated water while maintaining the pH value to be neutral, and to activate the anaerobic microorganisms supported on the filter member and promote the decomposition of the organic component (organic matter). .

  According to a sixth invention, in the method for treating nitric acid waste liquid according to any one of the first to fourth inventions, supply of the nitric acid waste liquid from the flow rate adjusting tank to the anaerobic tank based on a detected value of dissolved oxygen concentration in the nitric acid waste liquid in the anaerobic tank This is a method for treating nitric acid waste liquid, characterized in that the amount is adjusted.

  As a result, the nitric acid waste liquid in the anaerobic tank is maintained under anaerobic conditions, the denitrification reaction of the nitric acid waste liquid and the anaerobic microorganisms supported on the filter member are activated, and the decomposition of the organic component (organic matter) is promoted. it can.

  The seventh invention is a flow rate adjusting tank for storing nitric acid waste liquid, a supply means for supplying the nitric acid waste liquid in the flow rate adjusting tank to the anaerobic tank, and stirring for forming a circulation flow in the nitric acid waste liquid stored in the anaerobic tank. Means, a solid nutrient mainly composed of a carboxylic acid having 6 or more carbon atoms, which is fed into the circulating stream of the nitric acid waste liquid and promotes the denitrification reaction, and is located in the circulating stream of the nitric acid waste liquid, An apparatus for treating nitric acid waste liquid, comprising: a filtration member carrying anaerobic microorganisms that decompose an organic component contained in a salt; and suction means for sucking treated water that has passed through the filtration member.

  This eliminates the need for an aerobic tank equipped with an aerobic environment that creates an aerobic environment, and prevents a rise in BOD due to denitrification of nitric acid waste liquid and activation of anaerobic microorganisms in a single anaerobic tank. At the same time, it is possible to reduce the size and operating cost of the apparatus.

  8th invention is the processing apparatus of the nitric acid waste liquid of 7th invention, The stirring means which forms the downflow area part of nitric acid waste liquid in the center part in an anaerobic tank, and forms an upflow area part outside the said downflow area part The nitric acid waste liquid treatment apparatus is characterized in that a filtration member is positioned in the upward flow area of the nitric acid waste liquid.

  Accordingly, the nitric acid waste liquid flowing along the surface of the filter member hardly deposits a solid component or the like on the surface of the filter member, and a cake layer or the like is not easily formed. Further, even if a cake layer or the like is formed, the cake layer or the like is not easily compressed, and the flow rate of treated water to the upstream portion is high, so that a path for water to flow is formed. For this reason, clogging hardly occurs, and a decrease in filtration performance can be suppressed.

  According to a ninth aspect of the invention, there is provided a nitric acid waste liquid treatment apparatus according to the eighth aspect, wherein a supply pipe for supplying the nitric acid waste liquid in the flow rate adjusting tank to the downflow region in the anaerobic tank is positioned. This is a processing device.

  As a result, the newly supplied nitric acid waste liquid is uniformly mixed with the already circulating nitric acid waste liquid in the downflow area and flows into the upflow area, so that it is possible to eliminate the presence of nitric acid waste liquids having different treatment conditions.

  According to a tenth aspect of the invention, there is provided a nitric acid waste liquid treatment apparatus according to the seventh to ninth aspects of the invention, which is provided with a vibrating means for vibrating the filter member.

  As a result, the formation of a cake layer in which solid components and the like are deposited on the surface of the filtration member is further suppressed, clogging is hardly generated, and a decrease in filtration performance can be suppressed.

  An eleventh aspect of the invention is a nitric acid waste liquid treatment apparatus according to the seventh to tenth aspects of the invention, comprising a means for detecting the oxidation-reduction potential of a nitric acid waste liquid in an anaerobic tank or a means for detecting dissolved oxygen concentration. This is a processing apparatus.

  Thereby, the anaerobic microorganisms carried on the filter member can be activated, and the decomposition of the organic component (organic matter) can be promoted.

  An apparatus for treating nitric acid waste liquid according to an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram of a nitric acid waste liquid treatment apparatus, and FIG. 2 is a cross-sectional view of an anaerobic tank taken along line AA in FIG.

  1 and 2, a fixed amount of nitric acid waste liquid 4 is stored in a flow rate adjusting tank 1 through a supply pipe 2 and a valve 3. In order to fluidize the nitric acid waste liquid 4 stored in the flow rate adjusting tank 1 and prevent decay, an aeration pipe 5 is positioned at the lower part of the flow rate adjusting tank 1, and air is supplied to the aeration pipe 5 via an air pump 6 and a supply pipe 7. Supply. Further, a discharge pipe 8 and a valve 9 are provided in communication with the bottom of the flow rate adjusting tank 1 to discharge the nitric acid waste liquid stored in the flow rate adjusting tank 1 during maintenance or the like.

  The nitric acid waste liquid 4 stored in the flow rate adjusting tank 1 is sucked by a pump 10 (supply means) and supplied to the anaerobic tank 12 through the introduction pipe 11. A certain amount of nitric acid waste liquid 13 is stored in the anaerobic tank 12. A partition tube 14 is positioned substantially at the center of the anaerobic tank 12, and stirring means 16 is provided inside the partition tube 14 to form a downward flow region 15 of the nitric acid waste liquid 13.

  The stirring means 16 is constituted by a rotary blade 18 driven by a motor 17, but a pump may be used and is not limited to the configuration shown in the figure.

  The nitric acid waste liquid 4 from the flow rate adjusting tank 1 is sucked by a pump 10 and supplied to the descending flow area 15 through an introduction pipe 11. In addition, the solid nutrient salt 19 to be added to the nitric acid waste liquid 13 is supplied from the nutrient salt supply unit 20 to the downflow region 15.

  Further, the nitric acid waste liquid 13 in the partition tube 14 flows from the downflow region 15 to the outside of the partition tube 14 from the lower end portion of the partition tube 14 and the bottom portion of the anaerobic tank 12, and outside the partition tube 14. An upward flow area 21 of the nitric acid waste liquid 13 is formed.

  Furthermore, a circulating flow is formed in which the nitric acid waste liquid 13 flows from the upflow region 18 to the downflow region 15 again through the upper end of the partition tube 14.

  In addition, since a plurality of filtration members 22 having anaerobic microorganisms are positioned in the upward flow area 21 of the nitric acid waste liquid 13, the filtration member 22 includes a lower member 23 and an upper member 24 to constitute a filtration module 25. ing.

  The treated water that has passed through the filtration member 22 from the upper ends of the plurality of filtration modules 25 is sucked and discharged through the suction pipe 26 and the pump 27 (suction means). A vibration means 28 is provided at the lower end of the filtration module 25 to slightly vibrate the filtration module 25 itself.

  Further, an oxidation-reduction potential detecting means 29 and a dissolved oxygen amount detecting means 30 for the nitric acid waste liquid 13 are provided in the rising flow area 21 of the nitric acid waste liquid 13.

  A discharge pipe 31 and a valve 32 are provided in communication with the bottom of the anaerobic tank 12 to discharge the nitric acid waste liquid stored in the anaerobic tank 12 during maintenance.

  As the filtration member 22, a hollow fiber membrane, a microfiltration membrane (MF membrane), a dynamic membrane using an ultra fine mesh (net), a string-like fiber aggregate, or the like can be used.

  Next, the basic operation and action of the embodiment of the present invention will be described.

  The arrows in the figure indicate the flow of the nitric acid waste liquid 13.

  The nitric acid waste liquid 4 stored in the flow rate adjusting tank 1 is sucked by the pump 10 and stored in a certain amount in the anaerobic tank 12 through the introduction pipe 11, and the stirring means 16 is driven to lower the nitric acid waste liquid 13 in the partition cylinder 14. A basin 15 is formed.

  Further, the nitric acid waste liquid 13 in the partition tube 14 flows from the downflow region 15 to the outside of the partition tube 14 from the lower end portion of the partition tube 14 and the bottom portion of the anaerobic tank 12, and outside the partition tube 14. An upward flow area 21 of the nitric acid waste liquid 13 is formed. Furthermore, a circulating flow is formed in which the nitric acid waste liquid 13 flows from the upflow region 21 to the downflow region 15 again through the upper end of the partition tube 14.

  Next, the solid nutrient salt 19 to be applied to the nitric acid waste liquid 13 is supplied from the nutrient salt supply unit 20 to the descending basin unit 15. The plurality of solid nutrient salts 19 added at this time can be uniformly diffused in the nitric acid waste liquid 13 over the downflow area 15 and the upflow area 21 by the circulation flow of the nitric acid waste liquid 13.

  Next, the material composition and configuration example of the solid nutrient salt 19 in the embodiment of the present invention will be described.

First, the solid nutrient salt 19 is mainly composed of a carboxylic acid having 6 or more carbon atoms.
As the carboxylic acid, it is essential that the carbon number is 6 or more. If the carbon number is less than 6, the solubility in water is too high and the shape cannot be retained in a short period of time. In addition, it is not preferable because a long-term, stable nutrition cannot be applied.

  Moreover, although it is not necessary to provide the upper limit of carbon number in particular, it is considered that the material that can be obtained industrially in large quantities is about 18 carbon atoms, but it is not limited to those having 18 or less carbon atoms. Nor. In addition, the carboxylic acid used in this embodiment has a linear structure, and is preferably a saturated monocarboxylic acid. The reason is that the saturated monocarboxylic acid has a high melting point and is stable as compared with the unsaturated monocarboxylic acid, so that the dissolution in water is stable.

  Examples of the carboxylic acid satisfying the above requirements include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, and stearic acid. Furthermore, salts of these carboxylic acids, oxyacids, esters, and these Mixtures are also included.

  The carboxylic acid described above is formed into a granular body, or the carboxylic acid as the main component is supported on a carrier using a material having high biocompatibility such as cellulose, polyvinyl alcohol, polyethylene glycol, and the like. Can be used as In order to mold the carboxylic acid, it can be easily performed by a usual method such as a method in which the carboxylic acid is cooled to solidify after being inserted into a mold or the like while being heated above the melting point of the substance.

  For example, these are fixed on a granular material having a particle size of 1 to 3 mm, a molded product such as a plate or rod, or a carboxylic acid on a breathable urethane, continuous foam, string or woven fabric, or non-woven fabric (coating ) And the like can be used as a molded article for practical use.

  Furthermore, you may insert molded articles, such as an above described granular material and a support body, into the bag which water can approach inside. These supply the solid nutrient salt 19 having an arbitrarily selected required size from the nutrient salt supply unit 20 to the nitric acid waste liquid 13 to the downflow region 15.

  Since the plurality of solid nutrient salts 19 added as described above are uniformly diffused by the circulation flow of the nitric acid waste liquid 13 without staying in a part of the nitric acid waste liquid 13, the carboxylic acid is uniformly dissolved in the nitric acid waste liquid 13. Can be made.

  Furthermore, since these carboxylic acids have a low solubility in water and are saturated monocarboxylic acids having a linear structure, denitrifying bacteria can be sufficiently used as hydrogen donors. Moreover, denitrification reaction proceeds rapidly by forming these carboxylic acids into an appropriate shape, or carrying them in an appropriate carrier and adding and supplying them inside the anaerobic tank 12, and the solubility in water is small. Therefore, it is not necessary to continuously add a hydrogen donor such as methanol as in the prior art, and the denitrification reaction can be maintained for a long time with respect to the nitric acid waste liquid 13.

  As described above, the carboxylic acid can maintain the denitrification reaction for a long time with respect to the nitric acid waste liquid 13, but promotes denitrification mainly composed of the above-mentioned linear saturated monocarboxylic acid having 6 or more carbon atoms. In the method using the solid nutrient salt 19 as an agent, when the linear saturated monocarboxylic acid is supported on a carrier and formed into a particle, plate or rod, the actual carrier The body contains organic components (organic matter) such as stearic acid and phosphorus.

  For this reason, the said organic component dissolves in the nitric acid waste liquid which is the waste liquid to be treated in the anaerobic tank 12, which leads to an increase in BOD (biochemical oxygen demand), and can be discharged as treated water as it is. Can not.

  Furthermore, there is a need for aeration equipment that creates an aerobic environment in order to prevent an increase in BOD, which leads to an increase in size and complexity of the apparatus, high operating costs, and difficulty in maintenance.

  In order to solve the above-described problem, in the embodiment of the present invention, a plurality of filtration members 22 supporting anaerobic microorganisms are positioned in the upward flow area 21 of the nitric acid waste liquid 13, and the hollow filtration member 22 is disposed. A filtration module 25 is configured by providing a lower member 23 and an upper member 24.

  The treated water that has passed through the filtration member 22 from the upper ends of the plurality of filtration modules 25 is sucked and discharged through the suction pipe 26 and the pump 27.

  As a result, the organic components (organic matter) such as stearic acid and phosphorus contained in the carrier can be decomposed when contacting and passing through the plurality of filtration members 22 carrying anaerobic microorganisms. .

  As a result, aeration equipment that creates an aerobic environment for preventing the increase in BOD is not required, and the entire apparatus can be reduced in size, simplified, operation cost can be suppressed, and maintenance can be simplified. .

  Further, in the embodiment of the present invention, a plurality of filtration members 22 carrying anaerobic microorganisms are positioned in the upward flow area 21 of the nitric acid waste liquid 13.

  With this arrangement, a cross flow configuration is adopted in which the nitric acid waste liquid 13 as the liquid to be filtered flows on the surface side of the filtration member 22 in a direction along the surface of the filtration member 22, that is, in a direction intersecting with the flow that passes through the filtration member 22. Therefore, the nitric acid waste liquid 13 flowing along the surface of the filter member 22 makes it difficult for solid components or the like to be deposited on the surface of the filter member 22, and it becomes difficult to form a cake layer or the like.

  Further, even if a cake layer or the like is formed, the cake layer or the like is not easily compressed, and the flow rate of treated water to the upstream portion is high, so that a path for water to flow is formed. For this reason, clogging hardly occurs, and a decrease in filtration performance can be suppressed.

  A vibration means 28 is provided at the lower end of the filtration module 25 to slightly vibrate the filtration module 25 itself. As a result, the formation of a cake layer or the like due to the deposition of solid components or the like on the surface of the filter member 22 is further suppressed, clogging is unlikely to occur, and a decrease in filtration performance can be suppressed.

  In addition, depending on the denitrification reaction of the nitric acid waste liquid 13 in the anaerobic tank 12 and the decomposition state of the organic component (organic matter) by anaerobic microorganisms, the treated water is sucked through the suction pipe 26 and the pump 27. The nitric acid waste liquid in the flow rate adjustment tank 1 is newly supplied from the introduction pipe 11 located in the downflow area 15 in the anaerobic tank 12.

  As a result, the newly supplied nitric acid waste liquid is uniformly mixed with the already circulating nitric acid waste liquid in the downflow area 15 and flows to the upflow area 21, thereby eliminating the presence of nitric acid waste liquids having different processing conditions. it can.

  The nitric acid waste liquid oxidation-reduction potential detecting means 29 is provided in the anaerobic tank 12, and the supply amount of nitric acid waste liquid from the flow rate adjusting tank 1 to the anaerobic tank 12 by the pump 10 or the pump 27 is determined by the obtained detection value. The amount of treated water that has passed through the filtration member 22 is adjusted.

  As a result, the treated water can be discharged while maintaining the pH value neutral, and the anaerobic microorganisms carried on the filter member 22 are activated, and the decomposition of the organic component (organic matter) is promoted. it can. When the detected value of the oxidation-reduction potential detecting means 29 is higher than the specified value, the supply amount of nitric acid waste liquid from the flow rate adjusting tank 1 to the anaerobic tank 12 by the pump 10 is reduced and stopped.

  Alternatively, the suction amount of the treated water that has passed through the filtering member 22 by the pump 27 is adjusted to be reduced and stopped.

  Furthermore, a dissolved oxygen concentration detection means 30 for detecting the dissolved oxygen concentration of the nitric acid waste liquid in the anaerobic tank 12 is provided. If the dissolved oxygen concentration becomes higher than a specified value by the obtained detection value, anaerobic is generated from the flow rate adjusting tank 1. The supply amount of nitric acid waste liquid into the tank 12 is adjusted to be reduced or stopped. As a result, the nitric acid waste liquid in the anaerobic tank 12 is maintained under anaerobic conditions, the denitrification reaction of the nitric acid waste liquid 13 and the anaerobic microorganisms supported on the filter member 22 are activated, and the decomposition of the organic component (organic matter) is promoted. can do.

  As described above, according to the present invention, the denitrification reaction of nitric acid waste liquid and anaerobic microorganisms can be performed in a single anaerobic tank without the need for an aerobic tank equipped with aeration equipment for creating an aerobic environment. It is possible to provide a nitric acid waste liquid treatment method and a treatment apparatus capable of simultaneously preventing the increase in BOD by activating the catalyst and reducing the size and operating cost of the apparatus.

  It can be applied to waste liquid treatment that requires denitrification and BOD suppression.

1 is an overall configuration diagram of a nitric acid waste liquid treatment apparatus according to an embodiment of the present invention. Sectional drawing of the anaerobic tank in the AA line in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flow control tank 2 Supply pipe 3 Valve 4 Nitric acid waste liquid 5 Aeration pipe 6 Air pump 7 Supply pipe 8 Discharge pipe 9 Valve 10 Pump (supply means)
DESCRIPTION OF SYMBOLS 11 Introduction pipe 12 Anaerobic tank 13 Nitric acid waste liquid 14 Partition cylinder 15 Downflow area part 16 Agitation means 17 Motor 18 Rotary blade 19 Solid nutrient salt 20 Nutrition salt supply part 21 Upflow area part 22 Filter member 23 Lower member 24 Upper member 25 Filtration module 26 Suction tube 27 Pump (suction means)
28 Exciting means 29 Redox potential detecting means 30 Dissolved oxygen concentration detecting means 31 Exhaust pipe 32 Valve

Claims (11)

The nitric acid waste liquid is supplied from the flow rate adjustment tank to the anaerobic tank, and a circulation flow of the nitric acid waste liquid is formed in the anaerobic tank, and the carboxylic acid having 6 or more carbon atoms is the main component in the circulation flow of the nitric acid waste liquid. Supplying solid nutrient salt to promote the denitrification reaction, disposing the filter component carrying anaerobic microorganisms in the circulating flow of the nitric acid waste liquid and decomposing the constituents contained in the solid nutrient salt A method for treating a nitric acid waste liquid by sucking treated water from the filter member. A nitric acid waste liquid flows from the upstream to the downstream at a substantially central portion of the anaerobic tank, and a nitric acid waste liquid flows from the downstream to the upstream outside the downward flow area. The method for treating a nitric acid waste liquid according to claim 1, wherein a filtration member is disposed in the upflow region. The method for treating a nitric acid waste liquid according to claim 2, wherein the nitric acid waste liquid in the flow rate adjusting tank is supplied to a downward flow area provided in the anaerobic tank. The method for treating a nitric acid waste liquid according to claim 2 or 3, wherein the solid nutrient salt is supplied to a downward flow region provided in the anaerobic tank. According to the detected value of the oxidation-reduction potential of the nitric acid waste liquid in the anaerobic tank, the supply amount of the nitric acid waste liquid from the flow rate adjustment tank to the anaerobic tank or the suction amount of the treated water that has passed through the filtering member is adjusted. The method for treating a nitric acid waste liquid according to any one of claims 1 to 4. 5. The supply amount of the nitric acid waste liquid from the flow rate adjustment tank to the anaerobic tank is adjusted according to the detected value of the dissolved oxygen concentration of the nitric acid waste liquid in the anaerobic tank. 6. The nitric acid waste liquid treatment method described. Supply means for supplying the nitric acid waste liquid stored in the flow rate adjustment tank to the anaerobic tank, stirring means for forming a circulation flow in the nitric acid waste liquid stored in the anaerobic tank, and supply into the circulation flow of the nitric acid waste liquid Anaerobic substance that decomposes the organic nutrients contained in the solid nutrient salt and the solid nutrient salt mainly composed of carboxylic acid having 6 or more carbon atoms that promotes the denitrification reaction, and the nitric acid waste liquid. An apparatus for treating nitric acid waste liquid, comprising: a filtration member carrying microorganisms; and a suction means for sucking treated water that has passed through the filtration member. A stirring means for forming a descending flow region portion where the nitric acid waste liquid flows from the upstream to the downstream in the substantially central portion of the anaerobic tank, and forming an upward flow region portion where the nitric acid waste solution flows from the downstream to the upstream outside the descending flow region portion, The apparatus for treating nitric acid waste liquid according to claim 7, wherein a filtration member is disposed in the upward flow area of the nitric acid waste liquid. 9. The apparatus for treating nitric acid waste liquid according to claim 8, further comprising a supply pipe for supplying the nitric acid waste liquid in the flow rate adjusting tank to a downflow region formed in the anaerobic tank. The treatment apparatus for nitric acid waste liquid according to any one of claims 7 to 9, further comprising an oscillating means for vibrating the filter member. The redox potential detecting means for detecting the redox potential of the nitric acid waste liquid in the anaerobic tank or the dissolved oxygen concentration detecting means for detecting the dissolved oxygen concentration of the nitric acid waste liquid is provided. An apparatus for treating nitric acid waste liquid according to claim 1.

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