WO2019198388A1 - Nitrogen treatment method - Google Patents

Nitrogen treatment method Download PDF

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Publication number
WO2019198388A1
WO2019198388A1 PCT/JP2019/008702 JP2019008702W WO2019198388A1 WO 2019198388 A1 WO2019198388 A1 WO 2019198388A1 JP 2019008702 W JP2019008702 W JP 2019008702W WO 2019198388 A1 WO2019198388 A1 WO 2019198388A1
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Prior art keywords
nitrogen
treated
water
anaerobic ammonia
ammonia oxidation
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PCT/JP2019/008702
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French (fr)
Japanese (ja)
Inventor
宇田川　万規子
祥子 宮前
裕哉 木村
吉川　慎一
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株式会社日立製作所
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Publication of WO2019198388A1 publication Critical patent/WO2019198388A1/en

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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/02—Aerobic processes
    • C02F3/10—Packings; Fillings; Grids
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/34—Biological treatment of water, waste water, or sewage characterised by the microorganisms used
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

Definitions

  • the present invention relates to a nitrogen treatment method for wastewater, and more particularly to a nitrogen treatment method for biologically denitrifying nitrogen components contained in wastewater.
  • Wastewater containing nitrogen components causes eutrophication of closed waters and contributes to water pollution. Therefore, in some sewage treatment facilities and wastewater treatment facilities, nitrogen treatment is performed to decompose and remove nitrogen components contained in the wastewater using microorganisms.
  • nitrification / denitrification treatment that combines nitrification treatment and denitrification treatment has been widely used.
  • nitrification denitrification treatment ammonia nitrogen contained in the water to be treated is oxidized to nitrate nitrogen by nitrifying bacteria, and then nitrate nitrogen is converted to molecular nitrogen by denitrifying bacteria.
  • anaerobic ammonia oxidation (ANAMOX: Anaerobic Ammonium Oxidation) method has been put into practical use.
  • the anaerobic ammonia oxidation method is a method in which ammonia and nitrous acid are co-denitrified by anaerobic ammonia oxidizing bacteria.
  • ammonia nitrogen and nitrite nitrogen in the water to be treated are converted into molecular nitrogen and some nitrate nitrogen by an anaerobic ammonia oxidation reaction.
  • Anaerobic ammonia oxidation reaction is an autotrophic anaerobic ammonia-oxidizing bacterium that uses ammonia as a hydrogen donor, so there is no need to supply organic substances such as methanol, which has the advantage of reducing operating costs. . Moreover, since it is not necessary to oxidize nitrite nitrogen to nitrate nitrogen, the cost associated with aeration is also reduced. In addition, anaerobic ammonia-oxidizing bacteria show a high denitrification rate, but have a small growth amount, so that the equipment scale can be reduced without impairing the processing efficiency, and the amount of excess sludge is reduced.
  • Wastewater containing nitrogen components often contains ammoniacal nitrogen.
  • ammonium ions and nitrite ions react at a ratio of about 1: 1.3. Therefore, in the anaerobic ammonia oxidation method, nitrite nitrification in which a part of ammonia nitrogen is oxidized to nitrite nitrogen is performed in advance before the anaerobic ammonia oxidation reaction.
  • Nitrogen treatment by the anaerobic ammonia oxidation method consists of a single tank type that performs nitrite-type nitrification and anaerobic ammonia oxidation in one tank, an ammonia oxidation tank that performs nitrite-type nitrification, and an anammox reaction that performs anaerobic ammonia oxidation. It is roughly divided into two tank type using a tank.
  • Single tank type includes CANON method under aeration restricted to low oxygen concentration, OLAND method restricted under low oxygen concentration conditions, anaerobic ammonia oxidizing bacteria inside carrier with nitrifying bacteria attached and immobilized There are a SNAP method that is performed by proliferating and SBR method that is performed by a semi-batch method.
  • the two-tank type is a one-pass type in which the entire amount of water to be treated is introduced into the ammonia oxidation tank and a part of the ammonia nitrogen is partially nitrified, or a part of the water to be treated is introduced into the ammonia oxidation tank.
  • a bypass type that nitrites all of the ammoniacal nitrogen and diverts the remainder before joining.
  • Patent Document 1 discloses a process for reducing the concentration of organic substances contained in wastewater by methane fermentation, a process for converting ammonia nitrogen into nitrogen gas by anammox bacteria, and nitrification of ammonia nitrogen and nitrate nitrogen / suboxide.
  • a wastewater treatment method is described in which any activated sludge treatment for denitrifying nitrate nitrogen is performed based on the organic matter concentration of the wastewater.
  • Patent Document 2 discloses that organic substances are removed aerobically by non-aggregating bacteria, solid-liquid separation is performed using a pressure flotation separation process, and then a part of ammonia nitrogen is converted to nitrite nitrogen.
  • a waste water treatment method is described in which non-treated water containing oxidized nitrogen and nitrite nitrogen is denitrified by autotrophic denitrifying bacteria.
  • Patent Document 3 after removing organic substances in wastewater in an oxygen-free tank and generating nitrous acid, treated water that is anaerobically denitrified from nitrous acid and ammonia is produced, and this treated water is A wastewater treatment method is described in which the remaining ammonia is oxidized and then returned to the anoxic tank for circulation. In the anoxic tank, organic substances in the wastewater are removed by nitrite respiration or nitrate respiration.
  • Patent Document 1 since it is necessary to analyze the Kjeldahl nitrogen concentration and COD / N ratio of wastewater in advance, the operation of the processing apparatus becomes complicated, and a processing tank such as a methane fermentation processing tank is also provided. In such a case, the equipment becomes larger or the equipment cost increases. Further, in the method of Patent Document 2, since it is necessary to perform a solid-liquid separation process after decomposing an organic substance, the equipment cost and operation cost of the processing apparatus are increased, and downsizing of the equipment may be hindered.
  • an object of the present invention is to provide a nitrogen treatment method for efficiently treating wastewater containing nitrogen components and organic substances at low cost.
  • a nitrogen treatment method is a nitrogen treatment method for denitrifying nitrogen components contained in waste water, and is a microorganism that converts ammonia nitrogen and nitrite nitrogen contained in treated water into microorganisms.
  • Treat the treated water is a nitrogen treatment method for denitrifying nitrogen components contained in waste water, and is a microorganism that converts ammonia nitrogen and nitrite nitrogen contained in treated water into microorganisms.
  • waste water containing nitrogen components and organic substances can be efficiently treated at low cost.
  • the nitrogen treatment method relates to a method of denitrifying nitrogen components contained in waste water (treated water) by biological treatment.
  • This nitrogen treatment method includes at least an anaerobic ammonia oxidation treatment step of converting ammonia nitrogen and nitrite nitrogen contained in the water to be treated into molecular nitrogen by microbial sludge.
  • the water to be treated in the anaerobic ammonia oxidation treatment step, is treated using a fixed bed reactor in which a filler to which microbial sludge is immobilized is held.
  • a fixed bed reactor According to the fixed bed reactor, anaerobic ammonia oxidizing bacteria and heterotrophic microorganisms can be propagated in different regions in the treatment tank. Therefore, even if the water to be treated contains an organic substance in addition to the nitrogen component, it can be treated efficiently in a single tank.
  • FIG. 1 is a schematic diagram illustrating an example of a wastewater treatment apparatus used for nitrogen treatment.
  • the nitrogen treatment method according to this embodiment can be carried out using a wastewater treatment apparatus 100 as shown in FIG.
  • a wastewater treatment apparatus 100 shown in FIG. 1 includes an anaerobic ammonia oxidation tank 1 that is a fixed bed reactor, a filler 2 on which microbial sludge is immobilized, a supply pump 3, a pH adjuster 4, and ammonia oxidation.
  • a tank 5, a microorganism sludge 6, an air diffuser 7, a treated water tank 8, and a cleaning pump 9 are provided.
  • the wastewater treatment apparatus 100 is an apparatus for treating nitrogen-containing wastewater (treated water) with an anaerobic ammonia oxidation method, and is a two-tank type that performs nitrite-type nitrification and anaerobic ammonia oxidation in separate reaction tanks. It is said that. Since the anaerobic ammonia oxidation tank 1 that performs anaerobic ammonia oxidation treatment is a fixed bed reactor, the wastewater treatment apparatus 100 treats anaerobic anaerobic ammonia oxidizing bacteria and aerobic heterotrophic microorganisms. It can be propagated in different areas in the tank to decompose organic matter and anaerobic ammonia oxidation in a single tank.
  • the anaerobic ammonia oxidizing activity does not decrease because heterotrophic microorganisms with a fast growth rate predominately grow and anaerobic ammonia oxidizing bacteria with a slow growth rate are difficult to propagate. There is a tendency to destabilize.
  • heterotrophic microorganisms propagate on the upstream side in the treatment tank, and anaerobic ammonia-oxidizing bacteria propagate on the downstream side where the organic matter concentration is low, due to the organic matter contained in the water to be treated. Therefore, even if the water to be treated contains an organic substance, highly active and stable anaerobic ammonia oxidation activity can be obtained on the downstream side in the treatment tank.
  • treated water examples include wastewater discharged from business sites such as sewage treatment facilities, semiconductor factories, metal smelters, and chemical manufacturing facilities.
  • the waste water may contain nutrient salts such as phosphorus, carbon, and heavy metals in addition to ammonia nitrogen and organic matter.
  • the wastewater may be subjected to activated sludge treatment, denitrification treatment with heterotrophic denitrification bacteria, dephosphorization treatment, and the like before the nitrification treatment performed in the ammonia oxidation tank 1.
  • the anaerobic ammonia oxidation tank 1 is a fixed bed reactor in which a filler 2 on which microbial sludge is immobilized is held.
  • the filler 2 forming the fixed bed is held in a cylindrical treatment tank, and the water to be treated flows through the gap between the fillers 2.
  • a microbial sludge containing anaerobic ammonia-oxidizing bacteria and a microbial sludge containing heterotrophic microorganisms are immobilized on the filler 2.
  • the anaerobic ammonia oxidation tank 1 has an inlet at the upper part of the treatment tank and an outlet at the lower part of the treatment tank, and has a cylindrical fixed bed reactor for flowing the treated water as a downward flow.
  • An ammonia oxidation tank 5 is connected to the inlet through a pipe provided with a supply pump 3 and a pH adjusting device 4.
  • the treated water treated in the ammonia oxidation tank 5 is adjusted in pH as necessary, and is introduced into the anaerobic ammonia oxidation tank 1 by the supply pump 3.
  • the ammonia oxidation tank 5 is a treatment tank that performs a nitrite type nitrification treatment that oxidizes ammonia nitrogen contained in water to be treated into nitrite nitrogen.
  • the ammonia oxidation tank 5 holds microbial sludge 6 for biologically treating the water to be treated. Further, the ammonia oxidation tank 5 is provided with an air diffuser 7 for aeration of the water to be treated.
  • the microbial sludge 6 is a sludge containing bacteria, protists, etc., and contains a group of nitrifying bacteria.
  • the nitrifying bacteria group includes ammonia-oxidizing bacteria (AOB) classified into genus Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosolobus, etc., and Nitrobactor. ), Nitrospina, Nitrococcus, Nitrospira and the like, and nitrous oxide bacteria (NOB).
  • AOB ammonia-oxidizing bacteria
  • the microbial sludge 6 is fixed to the fluidized bed carrier in FIG.
  • the microbial sludge used in the ammonia oxidation tank 5 is in a state of being entrapped and immobilized inside the carrier, in a state of being entrapped and immobilized on the surface of the carrier, in a state of being adhered and immobilized on the carrier, by self-granulation Any of a state in which granules are formed and a state of floating sludge suspended in water may be used.
  • the immobilized microbial sludge may be used in any form of a fixed bed, a fluidized bed, and a moving bed.
  • Carrier materials include mono (meth) acrylates, di (meth) acrylates, tri (meth) acrylates, tetra (meth) acrylates, urethane (meth) acrylates, epoxy (meth) acrylates, polyvinyl alcohol , Vinylon, polyethylene glycol, polypropylene glycol, acrylamide, polyethylene, polypropylene, ethylene vinyl acetate copolymer, polyvinyl chloride, polyamides such as aramid and nylon, polyester, rayon, glass, activated carbon, etc. it can.
  • the shape of the carrier is an appropriate shape such as a cubic shape, a rectangular parallelepiped shape, a plate shape, a spherical shape, a disc shape, a cylindrical shape, a porous shape, a sponge shape, a fiber shape, a cloth shape, a coin shape, a lotus shape, or a chrysanthemum shape. be able to.
  • the size of the carrier is not particularly limited, and can be, for example, 3 mm square.
  • the air diffuser 7 includes, for example, a diffuser that generates bubbles and a diffuser pipe, a blower that supplies air, a compressor that compresses air, an air supply pipe that sends air from the blower to the diffuser and the diffuser pipe, and the like.
  • the aeration amount of the water to be treated may be controlled to be constant, or may be variably controlled so as to achieve a target nitrification rate according to the concentration of ammonia nitrogen, the concentration of nitrite nitrogen, or the like.
  • the pH adjusting device 4 is provided for adjusting the pH of the water to be treated that is subjected to the anaerobic ammonia oxidation treatment.
  • the pH adjusting device 4 includes, for example, a pH adjusting agent tank that stores the pH adjusting agent, a chemical injection pump that supplies the pH adjusting agent to the water to be treated, and the like.
  • a pH adjuster alkaline pH adjusters, such as sodium hydrogencarbonate and sodium hydroxide, can be used, for example.
  • the treated water treated in the ammonia oxidation tank 5 has an acidified pH adjusted to be near neutral.
  • the anaerobic ammonia oxidation tank 1 is an anaerobic ammonia that decomposes organic substances contained in the water to be treated and co-denitrifies ammonia nitrogen and nitrite nitrogen contained in the water to be treated by an anaerobic ammonia oxidation reaction. And oxidation treatment.
  • the organic matter treatment is performed by heterotrophic microorganisms held in the filler 2 on the upstream side (inlet side) in the treatment tank.
  • the anaerobic ammonia oxidation treatment is performed by anaerobic ammonia oxidizing bacteria held in the downstream side (outflow side) filler 2 in the treatment tank.
  • the anaerobic ammonia oxidation tank 1 is a fixed bed reactor, when treated water containing organic substances flows in, the organic substance concentration increases on the upstream side in the treatment tank, and on the filler 2 located on the upstream side, Heterotrophic microorganisms breed. And the organic matter and dissolved oxygen which are contained in to-be-processed water are consumed by the heterotrophic microorganism, and the to-be-processed water which the organic matter density
  • Microbial sludge used in a fixed bed reactor is in a state of being entrapped and immobilized inside the carrier, in a state of being entrapped and immobilized on the surface of the carrier, in a state of being adhered and immobilized on the carrier, or by self-granulation It is preferable that the granules are formed. That is, a carrier or granule can be used as the filler 2 for the fixed bed. When such a filler 2 is filled in the treatment tank, the water to be treated becomes difficult to mix and diffuse by the filling layer formed by the filler 2 itself. Therefore, concentration polarization of organic matter and dissolved oxygen can be easily generated without partitioning the fixed bed reactor.
  • the carrier filler 2 has an appropriate shape such as a cubic shape, a rectangular parallelepiped shape, a plate shape, a spherical shape, a disc shape, a cylindrical shape, a porous shape, a sponge shape, a fiber shape, a cloth shape, a coin shape, a lotus shape, and a chrysanthemum shape. It can be.
  • a resin pellet support such as a cubic shape or a rectangular parallelepiped shape is particularly preferably used from the viewpoint that the retained amount of microbial sludge and the specific surface area are large and the fixed bed reactor can be easily filled.
  • the size of the carrier is not particularly limited, and can be, for example, 3 mm square.
  • the material of the carrier can be the same as that of the ammonia oxidation tank 1.
  • the carrier filler 2 preferably has a specific gravity of at least 1 g / cm 3 and is sedimentable.
  • the filler 2 is a sedimentary carrier, when the fixed bed reactor is directly filled, it becomes difficult to flow even if the water to be treated is passed. Therefore, it is possible to clearly separate the habitats of anaerobic ammonia oxidizing bacteria and heterotrophic microorganisms into upstream and downstream sides in the treatment tank to obtain highly active and stable anaerobic ammonia oxidizing activity. it can.
  • the filling rate of the filler 2 is preferably 60% or more, more preferably 70% or more, and further preferably 80% or more per packed bed.
  • the filling rate is preferably 90% or less.
  • the apparent volume calculated by the effective height in the direction of water flow of the water to be treated is used. With such a high filling rate, it becomes difficult for the water to be treated to be stirred by the carrier or granule filled as the filler 2. Therefore, it is possible to obtain a highly active and stable anaerobic ammonia oxidizing activity by separating the habitats of the anaerobic ammonia oxidizing bacteria and the heterotrophic microorganisms in the direction of water flow. Moreover, since the total surface area of the filler 2 becomes large, a high denitrification rate can be obtained.
  • one kind of immobilized anaerobic ammonia oxidizing bacteria and heterotrophic microorganisms may be held in a fixed bed reactor, or the filler 2 immobilized with anaerobic ammonia oxidizing bacteria,
  • the filler 2 on which the nutritional microorganisms are immobilized may be held in a fixed bed type reactor in the direction of water flow of the water to be treated.
  • the habitat can be separated in a short acclimatization time. it can.
  • the carrier or granule as the filler 2 may be directly stored, or may be stored in a container having an opening, and the container may be charged into the fixed bed type reactor.
  • a strainer type, a colander type or the like can be used as the container.
  • the filler 2 When the filler 2 is accommodated in the container, it may be packed so densely that the fillers 2 are in contact with each other, or may be accommodated in a sparse state where the fillers 2 are not easily in contact with each other. If the filling rate per container is low, the filler 2 can flow in the container, so that it is difficult to separate the habitat of anaerobic ammonia oxidizing bacteria and heterotrophic microorganisms, but blockage in the treatment tank is prevented.
  • the fixed bed reactor is preferably a piston flow type treatment tank. If it is a piston flow type, compared with the case of a complete mixing type, to-be-processed water becomes difficult to carry out a diffusive mixing. Because the treated water flows at a highly uniform linear velocity and concentration polarization of organic matter and dissolved oxygen is likely to occur, each habitat of anaerobic ammonia-oxidizing bacteria and heterotrophic microorganisms can be separated from the upstream side of the treatment tank. It is possible to obtain a highly active and stable anaerobic ammonia oxidation activity by clearly separating into the downstream side.
  • the inside of the processing tank may be partitioned into a plurality of compartments by an eye plate, a partition plate, a gabion or the like. If the inside of the treatment tank is partitioned in the direction of water to be treated, the position of the filler 2 does not change greatly even if the water to be treated is passed, so that each of anaerobic ammonia oxidizing bacteria and heterotrophic microorganisms It is possible to obtain a highly active and stable anaerobic ammonia oxidation activity by clearly separating the habitat. In addition, since the filler 2 in the upstream compartment and the filler 2 in the downstream compartment are not mixed, high-speed agitation with a stirrer is possible, and a high denitrification rate can be obtained.
  • the treated water tank 8 is provided for receiving treated water treated in the anaerobic ammonia oxidation tank 1. A part of the treated water treated in the anaerobic ammonia oxidation tank 6 is transferred to the treated water tank 8 and temporarily stored. Then, the treated water in the treated water tank 8 is returned to the anaerobic ammonia oxidation tank 6 by the cleaning pump 9 at an arbitrary time.
  • the cleaning pump 9 can physically clean the filler 2 by flowing treated water whose pressure is higher than that of the supply pump 3 into the fixed bed reactor from the inlet opening below the filler 2. .
  • Nitrogen treatment by the anaerobic ammonia oxidation method is included in the nitrification process that generates ammonia and nitrite nitrogen by oxidizing ammonia nitrogen contained in the treated water with microbial sludge, and is included in the treated water treated in the nitrification process.
  • anaerobic ammonia oxidation treatment is often performed in a completely mixed flow field using a fluidized bed type treatment tank. Since the growth rate of heterotrophic microorganisms is faster than that of anaerobic ammonia oxidizing bacteria, if the treated water contains organic matter, the heterotrophic microorganisms predominately grow in the treatment tank and anaerobic ammonia oxidizing activity May not be sufficiently obtained, or may become unstable during anaerobic ammonia oxidation treatment, and the nitrogen removal rate may not be stable.
  • activated sludge treatment or the like has been performed in advance for the purpose of treating organic substances contained in raw water.
  • the activated sludge treatment or the like is performed as an essential pretreatment, the equipment becomes larger and the equipment cost increases, so that the advantages of the anaerobic ammonia oxidation method may be impaired.
  • anaerobic ammonia oxidizing bacteria is inhibited by dissolved oxygen. Since aeration is performed in the activated sludge treatment, it is necessary to deaerate the dissolved oxygen before the anaerobic ammonia oxidation treatment.
  • the deaeration treatment can be performed by aeration such as nitrogen gas, forced deaeration by stirring water to be treated, and natural deaeration, but in the method of performing the deaeration treatment using an individual adjustment tank, Equipment becomes complicated and pretreatment takes a long time.
  • the nitrogen treatment method in the anaerobic ammonia oxidation treatment process, water to be treated is treated using a fixed bed reactor filled with a filler in which microbial sludge is immobilized.
  • the efficiency of the anaerobic ammonia oxidation treatment can be made less susceptible to the organic matter concentration and dissolved oxygen concentration of the raw water.
  • the total nitrogen concentration of the water to be treated and the ammonia nitrogen concentration are preferably 1 mg / L or more and 1000 mg / L or less from the viewpoint of avoiding the inhibition of anaerobic ammonia oxidation activity. Further, from the viewpoint of maximizing the effectiveness of the fixed bed reactor, a low concentration range in which it is inherently difficult to achieve a high nitrogen removal rate is more preferable. Specifically, the concentration of total nitrogen and the concentration of ammoniacal nitrogen in the water to be treated are more preferably 10 mg / L or more and 150 mg / L or less.
  • the water to be treated can be diluted in advance with anaerobic ammonia oxidation treated water or the like before the anaerobic ammonia oxidation treatment step. Moreover, when it is necessary to acclimate the microbial sludge, first, after the diluted water to be treated is introduced, the water can be passed with gradually increasing the concentration of total nitrogen and ammonia nitrogen.
  • the nitrification treatment step is performed in the ammonia oxidation tank 5 holding the nitrifying bacteria group while performing alkali addition and pH adjustment as necessary under aerobic conditions.
  • the water temperature of the water to be treated is preferably 10 ° C. or higher and 40 ° C. or lower.
  • pH of to-be-processed water is pH6 or more and pH10 or less. The pH of the water to be treated decreases to the acidic side as the nitritation of ammoniacal nitrogen proceeds.
  • the water to be treated for nitrification is preferably adjusted to a dissolved oxygen concentration such that the ratio of the ammonia nitrogen concentration to the nitrite nitrogen concentration is 1: 1 to 1: 1.5.
  • the dissolved oxygen concentration is adjusted within a range of 0.5 mg / L or more and 4.0 mg / L or less, the nitrification rate of the nitrite type nitrification becomes an appropriate range.
  • an anaerobic ammonia oxidation reaction proceeds efficiently in the case of a one-pass process, so that a high nitrogen removal rate can be obtained.
  • the anaerobic ammonia oxidation treatment step is performed by adjusting the pH as necessary under anoxic conditions in the anaerobic ammonia oxidation tank 1 holding anaerobic ammonia oxidizing bacteria and heterotrophic microorganisms.
  • the pH of the water to be treated is preferably pH 6.5 or more and pH 9 or less, more preferably pH 7 or more and pH 8.2 or less.
  • the water temperature of to-be-processed water becomes like this.
  • it is 10 to 40 degreeC, More preferably, it is 15 to 37 degreeC.
  • the biochemical oxygen demand (BOD) of the water to be treated is preferably 300 mg / L or less, preferably 150 mg / L or less at the inlet of the anaerobic ammonia oxidation tank 1 which is a fixed bed reactor. More preferably. With such a BOD, the organic matter can be sufficiently decomposed in a fixed bed reactor that allows water to flow at a normal flow rate. Even if the residence time is not greatly extended, the organic substance concentration on the downstream side in the treatment tank is sufficiently lowered, so that highly active and stable anaerobic ammonia oxidation activity can be obtained.
  • the anaerobic ammonia oxidation tank 1 which is a fixed bed reactor treats the water to be treated under anaerobic conditions in which aeration is not performed and the dissolved oxygen concentration is not increased. If sufficient dissolved oxygen remains in the water to be treated, heterotrophic microorganisms can easily grow on the upstream side in the treatment tank without aeration. If the dissolved oxygen concentration does not increase, the organic matter concentration of the water to be treated flowing downstream tends to decrease, and the anaerobic ammonia-oxidizing bacteria easily grow on the downstream side in the treatment tank. Therefore, according to such an operation, treated water after nitrification treatment containing organic matter and dissolved oxygen can be efficiently denitrified at low cost without being degassed in advance.
  • the treated water treated in the anaerobic ammonia oxidation tank 1 which is a fixed bed type reactor is caused to flow into the fixed bed type reactor from the inlet opening below the filler 2, and the microorganisms Can be physically washed.
  • the washing pump 9 By pressing the treated water into the fixed bed reactor with the washing pump 9, it is possible to prevent the packed bed formed by the filler 2 from being clogged with a microbial membrane or the like.
  • the physical cleaning of the filler 2 may be performed regularly at predetermined time intervals or irregularly during the anaerobic ammonia oxidation treatment of the water to be treated.
  • the development rate of backwashing necessary for physical washing depends on the linear velocity of treated water (Linear Velocity: LV) at the same water temperature and varies depending on the size and specific gravity of the carrier or granule. Therefore, it is preferable to obtain in advance the relationship between the expansion rate and the linear velocity for each carrier or granule to be used.
  • the fixed bed reactor since the fixed bed reactor is used in the anaerobic ammonia oxidation treatment step, organic substances can be decomposed on the upstream side of the treatment tank and anaerobic ammonia oxidation can be performed on the downstream side of the treatment tank.
  • the anaerobic ammonia-oxidizing bacteria and heterotrophic microorganisms have separate habitats, so even if the treated water contains organic matter or dissolved oxygen, it is highly active. And stable anaerobic ammonia oxidation activity can be obtained.
  • the fixed bed reactor can increase the amount of microbial sludge retained as compared with the fluidized bed processing tank, the denitrification rate per volume of the processing tank can be easily improved. Therefore, waste water containing nitrogen components and organic substances can be treated efficiently.
  • the decomposition activity of organic substances by heterotrophic microorganisms and the highly active and stable anaerobic ammonia oxidation activity by anaerobic ammonia oxidizing bacteria should be used in a single tank type treatment tank. Can do. Even if the pretreatment such as activated sludge treatment and deaeration treatment is omitted or the pretreatment time is shortened, the decomposition of organic substances and the anaerobic ammonia oxidation reaction should be performed only with the fixed bed reactor. Can do. Therefore, waste water containing nitrogen components and organic substances can be efficiently treated at low cost.
  • FIG. 2 is a schematic diagram illustrating another example of a wastewater treatment apparatus used for nitrogen treatment.
  • the nitrogen treatment method according to the present embodiment can also be carried out using a wastewater treatment apparatus 200 as shown in FIG.
  • a wastewater treatment apparatus 200 shown in FIG. 2 includes an anaerobic ammonia oxidation tank 1 that is a fixed bed reactor, a filler 2 on which microorganisms are immobilized, a supply pump 3, a pH adjuster 4, and a solution storage tank 10. And a solution supply pump 11.
  • the configuration of the supply pump 3, the pH adjustment device 4, the anaerobic ammonia oxidation tank 1, and the filler 2 is substantially the same as that of the wastewater treatment device 100.
  • the wastewater treatment apparatus 200 is an apparatus that treats wastewater containing nitrogen components (treated water) by anaerobic ammonia oxidation, and mixes a solution containing nitrite nitrogen with the treated water containing ammoniacal nitrogen.
  • An anaerobic ammonia oxidation treatment is employed.
  • the anaerobic ammonia oxidation tank 1 is a fixed-bed reactor, anaerobic ammonia oxidation bacteria and heterotrophic microorganisms are propagated in different areas in the treatment tank to decompose organic matter. Anaerobic ammonia oxidation can be performed.
  • the anaerobic ammonia oxidation tank 1 is a fixed bed reactor filled with a filler 2 on which microbial sludge is immobilized.
  • a microbial sludge containing anaerobic ammonia-oxidizing bacteria and a microbial sludge containing heterotrophic microorganisms are immobilized on the filler 2.
  • the filler 2 forming the fixed bed is held in a cylindrical processing tank so that the water to be treated can be passed through the gap of the filler 2.
  • the anaerobic ammonia oxidation tank 1 has an inlet at the lower part of the treatment tank and an outlet at the upper part of the treatment tank, and has a cylindrical fixed bed reactor for flowing the water to be treated as an upward flow. Has been. According to the form of flowing upward flow, microbial sludge is prevented from accumulating at the bottom, and accumulation of nitrogen gas or carbon dioxide produced by microbial sludge in the packed bed is suppressed.
  • the water to be treated is supplied to the inflow port via a pipe provided with the supply pump 3.
  • the solution storage tank 10 is connected via a pipe provided with a solution supply pump 11.
  • a solution containing nitrite nitrogen such as a sodium nitrite solution and a potassium nitrite solution is prepared.
  • the water to be treated containing ammoniacal nitrogen and organic substances is supplied to the anaerobic ammonia oxidation tank 1 by a supply pump 3.
  • a solution containing nitrite nitrogen can be supplied from the solution storage tank 10 by the solution supply pump 11.
  • the to-be-treated water containing ammonia nitrogen and the solution containing nitrite nitrogen are mixed and introduced into the anaerobic ammonia oxidation tank 1 to decompose organic matter and anaerobic ammonia oxidation.
  • the treated water supplied to the anaerobic ammonia oxidation tank 1 contains nitrite nitrogen so that the ratio of the ammonia nitrogen concentration to the nitrite nitrogen concentration is 1: 1 to 1: 1.5. It is preferable to mix with the solution containing. When adjusted to such a concentration ratio, the anaerobic ammonia oxidation reaction proceeds efficiently, so that a high nitrogen removal rate can be obtained.
  • the supply amount of the solution containing nitrite nitrogen is preferably controlled by measuring in advance the concentration of ammonia nitrogen in the treated water to be supplied.
  • the anaerobic ammonia oxidation tank 1 is provided with a circulation line for returning the treated water treated in the anaerobic ammonia oxidation tank 1 to the treatment tank.
  • a circulation line for returning the treated water treated in the anaerobic ammonia oxidation tank 1 to the treatment tank.
  • the ammonia nitrogen concentration and the organic matter concentration in the anaerobic ammonia oxidation tank 1 can be diluted.
  • heterotrophic denitrifying bacteria that use organic matter can reduce nitrate nitrogen remaining in the treated water to molecular nitrogen, thus increasing the nitrogen removal rate. it can.
  • the return of the treated water through the circulation line is preferably performed when the BOD of the treated water exceeds 300 mg / L at the inlet of the anaerobic ammonia oxidation tank 1.
  • the circulation line is preferably connected to the inlet of the water to be treated as shown in FIG.
  • the circulation line may be connected to the inlet of the water to be treated as shown in FIG. 2, or may be connected to the intermediate part where the habitat is separated. It is preferable to connect to.
  • the linear velocity of the water to be treated that flows as an upward flow is preferably 20 m / h or less when the filler 2 is a carrier.
  • the filler 2 is granule, 2 m / h or less is preferable.
  • the upstream filler 2 and the downstream filler 2 are difficult to mix, so that the habitats of anaerobic ammonia-oxidizing bacteria and heterotrophic microorganisms are clearly separated. be able to.
  • the fixed bed reactor since the fixed bed reactor is used in the anaerobic ammonia oxidation treatment step, organic substances can be decomposed upstream of the treatment tank and anaerobic ammonia oxidation can be performed downstream of the treatment tank. . Since the solution containing nitrite nitrogen is mixed with the water to be treated containing ammonia nitrogen, when the water to be treated does not contain nitrite nitrogen or the concentration of nitrite nitrogen is not appropriate Even an anaerobic ammonia oxidation treatment can be efficiently performed. For example, even if the nitrite type nitrification treatment is omitted or the nitrification rate in the nitrification treatment is arbitrarily changed, a high nitrogen removal rate can be obtained.
  • the ammonia oxidation tank 5 is a one-pass type that nitrifies the entire amount of water to be treated, but may be a bypass type. That is, a part of the water to be treated is introduced into the ammonia oxidation tank 5 to oxidize the entire amount of ammonia nitrogen to nitrite nitrogen, and the remainder is bypassed to the anaerobic ammonia oxidation tank 1 without nitrite type nitrification. You may join.
  • the wastewater treatment apparatus 100 may be operated in an upward flow, and the wastewater treatment apparatus 200 may be operated in a downward flow.
  • the wastewater treatment apparatus 100 may be provided with a circulation line for returning the treated water treated in the anaerobic ammonia oxidation tank 1 to the anaerobic ammonia oxidation tank 1, or the wastewater treatment apparatus 200 is not provided with a circulation line. May be.
  • the pH adjusting device 4 may be provided on either the supply side of the anaerobic ammonia oxidation tank 1 or the circulation line.
  • the waste water treatment apparatus 100, 200 may be provided with a circulation line for returning the treated water treated in the anaerobic ammonia oxidation tank 1 to the ammonia oxidation tank 5.
  • a circulation line for returning the treated water treated in the anaerobic ammonia oxidation tank 1 to the ammonia oxidation tank 5.
  • the nitrite nitrogen concentration in the ammonia oxidation tank 1 can be diluted.
  • the fixed bed reactor can be equipped with a stirring device that stirs the water to be treated as long as concentration polarization of organic matter or dissolved oxygen occurs.
  • the blade shape of the stirrer can be, for example, a paddle wing type, an anchor wing type, a ribbon wing type, a gate wing type, a propeller wing type, a pincushion wing type, or the like.
  • Rotation speed (rpm) of the stirrer is preferably 200 min -1 or less, 100 min -1 or less is more preferable. With such a slow speed, the habitat can be separated while maintaining the concentration polarization.
  • the shape of the fixed bed reactor is not particularly limited.
  • an appropriate shape such as a cylindrical shape, a rectangular tube shape, a polygonal tube shape, or a multiple tube shape can be used.
  • the effective width (length or diameter of the short side in the treatment tank) of the fixed bed reactor is 30 times or more the size of the carrier or granule (length or length of the long side). It is preferable that the length is 50 times or more. With such dimensions, the support or granule is less likely to be biased in the fixed bed reactor, so that the packed bed can be prevented from being blocked or the depleted unfilled portion from penetrating the packed bed. .
  • the gap between the fillers 2 filled in the fixed bed reactor is preferably 0.7 mm or more and preferably 3 mm or more when the non-pellet-like filler 2 is fixed to the fixed bed reactor. More preferred. Since it becomes difficult for the fillers 2 to contact each other with such dimensions, microbial sludge peeling, carrier cracking, tearing, and the like can be suppressed. As a result of the filler 2 becoming difficult to be damaged, blockage of the filler layer due to debris is also suppressed.
  • the anterior stage of the anaerobic ammonia oxidation tank 1 and the ammonia oxidation tank 5 is an adjustment tank that adjusts the quality and amount of waste water, and organic substances contained in the waste water.
  • a biological reaction tank that decomposes chemically, a pre-denitrification tank that denitrifies nitrate nitrogen contained in wastewater in advance, and the like may be provided.
  • a post-denitrification tank or the like for denitrifying nitrate nitrogen generated by the anaerobic ammonia oxidation reaction may be provided on the rear side.
  • a mixing tank for mixing a solution containing nitrate nitrogen may be provided on the front side of the wastewater treatment apparatus 200.
  • Example 1 A entrapping immobilization support was prepared in which microbial sludge, which is a hybrid of anaerobic ammonia oxidizing bacteria and activated sludge containing heterotrophic microorganisms, was immobilized.
  • the entrapping immobilization support was filled in a reactor having a volume of 0.5 L so as to have a volume of 0.3 L, and the fixed bed reactor was placed in a constant temperature bath at 20 ° C. Then, the raw water having an ammonia nitrogen concentration of 40 mg-N / L and a BOD of 50 mg / L is used.
  • the ratio of the ammonia nitrogen concentration to the nitrite nitrogen concentration is 1: 1 to 1: 1.5.
  • the concentration of ammonia nitrogen was 0.2 mg / L
  • the concentration of nitrite nitrogen was 0.9 mg / L
  • the concentration of nitrate nitrogen was 6 mg / L.
  • the carrier filled in the reactor has a brown color on the lower side where the water to be treated that has undergone nitrification flows, and it was confirmed that heterotrophic microorganisms had propagated.
  • the red color of the upper part of the reactor became stronger and the growth of anaerobic ammonia oxidizing bacteria was confirmed.
  • a entrapping immobilization support was prepared in which microbial sludge, which is a hybrid of anaerobic ammonia oxidizing bacteria and activated sludge containing heterotrophic microorganisms, was immobilized.
  • This entrapping immobilization support was put into a reactor having a volume of 0.5 L so as to have a volume of 0.1 L, and this fluidized bed reactor was placed in a constant temperature bath at 20 ° C. Then, the raw water having an ammonia nitrogen concentration of 40 mg-N / L and a BOD of 50 mg / L is used.
  • the ratio of the ammonia nitrogen concentration to the nitrite nitrogen concentration is 1: 1 to 1: 1.5.
  • the concentration of ammonia nitrogen was 15 mg / L
  • the concentration of nitrite nitrogen was 15 mg / L
  • the concentration of nitrate nitrogen was 0.6 mg / L.
  • the carrier introduced into the reactor is generally brown, and there is a possibility that heterotrophic microorganisms have propagated. However, the red carrier indicating the growth of anaerobic ammonia-oxidizing bacteria is almost confirmed. Was not.
  • Example 1 As shown in the results of Example 1 and Comparative Example 1, the efficiency of nitrogen treatment is different between a fixed bed reactor that causes concentration polarization and a fluidized bed reactor that is completely mixed.
  • the anaerobic ammonia oxidizing bacteria did not propagate sufficiently, and almost no anaerobic ammonia oxidizing activity was observed, whereas in the fixed bed reactor of Example 1, anaerobic ammonia was used. Oxidizing bacteria grew and a high nitrogen removal rate was obtained.

Abstract

The present invention provides a nitrogen treatment method which efficiently treats wastewater that contains a nitrogen component and an organic matter at low cost. A nitrogen treatment method which denitrifies a nitrogen component that is contained in wastewater, and which comprises an anaerobic ammonia oxidation treatment step for converting ammoniacal nitrogen and nitrite nitrogen contained in water to be treated into molecular nitrogen by means of microorganism sludge. In the anaerobic ammonia oxidation treatment step, water to be treated is treated with use of a fixed-bed reactor wherein a filler (such as a carrier and granules), on which microorganism sludge is immobilized, is held.

Description

窒素処理方法Nitrogen treatment method
　本発明は、廃水の窒素処理方法に係り、特に、廃水に含まれる窒素成分を生物学的に脱窒する窒素処理方法に関する。 The present invention relates to a nitrogen treatment method for wastewater, and more particularly to a nitrogen treatment method for biologically denitrifying nitrogen components contained in wastewater.
　窒素成分を含む廃水は、閉鎖性水域の富栄養化を招き、水質汚染を引き起こす一因となっている。そのため、一部の下水処理施設や廃水処理施設では、廃水に含まれている窒素成分を微生物を利用して分解除去する窒素処理が行われている。 廃 Wastewater containing nitrogen components causes eutrophication of closed waters and contributes to water pollution. Therefore, in some sewage treatment facilities and wastewater treatment facilities, nitrogen treatment is performed to decompose and remove nitrogen components contained in the wastewater using microorganisms.
　従来、窒素成分を含む廃水を生物学的に窒素処理する方法としては、硝化処理と脱窒処理とを組み合わせて行う硝化脱窒処理が広く用いられてきた。硝化脱窒処理では、被処理水中に含まれているアンモニア性窒素が硝化細菌によって硝酸性窒素にまで酸化された後、硝酸性窒素が脱窒細菌によって分子状窒素に変換されている。 Conventionally, as a method of biologically nitrogen-treating wastewater containing nitrogen components, nitrification / denitrification treatment that combines nitrification treatment and denitrification treatment has been widely used. In nitrification denitrification treatment, ammonia nitrogen contained in the water to be treated is oxidized to nitrate nitrogen by nitrifying bacteria, and then nitrate nitrogen is converted to molecular nitrogen by denitrifying bacteria.
　一方、近年では、嫌気性アンモニア酸化（アナモックス（ＡＮＡＭＭＯＸ：Anaerobic Ammonium Oxidation））法の実用化も進められている。嫌気性アンモニア酸化法は、アンモニアと亜硝酸とを嫌気性アンモニア酸化細菌によって共脱窒する方法である。嫌気性アンモニア酸化法によると、被処理水中のアンモニア性窒素と亜硝酸性窒素とが、嫌気性アンモニア酸化反応によって、分子状窒素と若干の硝酸性窒素とに変換される。 On the other hand, in recent years, anaerobic ammonia oxidation (ANAMOX: Anaerobic Ammonium Oxidation) method has been put into practical use. The anaerobic ammonia oxidation method is a method in which ammonia and nitrous acid are co-denitrified by anaerobic ammonia oxidizing bacteria. According to the anaerobic ammonia oxidation method, ammonia nitrogen and nitrite nitrogen in the water to be treated are converted into molecular nitrogen and some nitrate nitrogen by an anaerobic ammonia oxidation reaction.
　嫌気性アンモニア酸化反応は、独立栄養性である嫌気性アンモニア酸化細菌がアンモニアを水素供与体として行う反応であるため、メタノール等の有機物を供給する必要が無く、運転コストが抑制される利点がある。また、亜硝酸性窒素を硝酸性窒素にまで酸化する必要が無いため、曝気に関わるコストも削減される。また、嫌気性アンモニア酸化細菌は高い脱窒速度を示す一方で増殖量が少ないため、処理効率を損なわず設備規模を縮小することが可能であり、余剰汚泥の量が少なくなるという利点もある。 Anaerobic ammonia oxidation reaction is an autotrophic anaerobic ammonia-oxidizing bacterium that uses ammonia as a hydrogen donor, so there is no need to supply organic substances such as methanol, which has the advantage of reducing operating costs. . Moreover, since it is not necessary to oxidize nitrite nitrogen to nitrate nitrogen, the cost associated with aeration is also reduced. In addition, anaerobic ammonia-oxidizing bacteria show a high denitrification rate, but have a small growth amount, so that the equipment scale can be reduced without impairing the processing efficiency, and the amount of excess sludge is reduced.
　窒素成分を含む廃水は、多くの場合、アンモニア性窒素を含有している。一方、嫌気性アンモニア酸化反応では、アンモニウムイオンと亜硝酸イオンとが約１：１．３の比率で反応する。そのため、嫌気性アンモニア酸化法では、アンモニア性窒素の一部を亜硝酸性窒素にまで酸化させておく亜硝酸型硝化が、嫌気性アンモニア酸化反応の前に予め行われている。 廃 Wastewater containing nitrogen components often contains ammoniacal nitrogen. On the other hand, in the anaerobic ammonia oxidation reaction, ammonium ions and nitrite ions react at a ratio of about 1: 1.3. Therefore, in the anaerobic ammonia oxidation method, nitrite nitrification in which a part of ammonia nitrogen is oxidized to nitrite nitrogen is performed in advance before the anaerobic ammonia oxidation reaction.
　嫌気性アンモニア酸化法による窒素処理の方式は、亜硝酸型硝化と嫌気性アンモニア酸化とを一槽で行う単槽式と、亜硝酸型硝化を行うアンモニア酸化槽と嫌気性アンモニア酸化を行うアナモックス反応槽を用いる二槽式とに大別される。 Nitrogen treatment by the anaerobic ammonia oxidation method consists of a single tank type that performs nitrite-type nitrification and anaerobic ammonia oxidation in one tank, an ammonia oxidation tank that performs nitrite-type nitrification, and an anammox reaction that performs anaerobic ammonia oxidation. It is roughly divided into two tank type using a tank.
　単槽式としては、低酸素濃度に制限した曝気の下で行うＣＡＮＯＮ法、低酸素濃度の条件に制限して行うＯＬＡＮＤ法、硝化細菌群を付着固定化した担体の内部に嫌気性アンモニア酸化細菌を増殖させて行うＳＮＡＰ法、半回分方式で行うＳＢＲ法等がある。 Single tank type includes CANON method under aeration restricted to low oxygen concentration, OLAND method restricted under low oxygen concentration conditions, anaerobic ammonia oxidizing bacteria inside carrier with nitrifying bacteria attached and immobilized There are a SNAP method that is performed by proliferating and SBR method that is performed by a semi-batch method.
　また、二槽式としては、被処理水の全量をアンモニア酸化槽に導入してアンモニア性窒素の一部を部分亜硝酸化するワンパス式や、被処理水の一部をアンモニア酸化槽に導入してアンモニア性窒素の全部を亜硝酸化し、残部を迂回させてから合流させるバイパス式がある。 In addition, the two-tank type is a one-pass type in which the entire amount of water to be treated is introduced into the ammonia oxidation tank and a part of the ammonia nitrogen is partially nitrified, or a part of the water to be treated is introduced into the ammonia oxidation tank. There is a bypass type that nitrites all of the ammoniacal nitrogen and diverts the remainder before joining.
　従来、嫌気性アンモニア酸化細菌の純粋培養系が確立された例はなく、嫌気性アンモニア酸化法には、主として、馴化をさせた汚泥や、種汚泥を集積培養した汚泥が用いられている。嫌気性アンモニア酸化細菌は、増殖速度が極めて遅いため、被処理水の有機物濃度が高いと、増殖速度が速い従属栄養性微生物が優占増殖し、嫌気性アンモニア酸化細菌が繁殖し難くなる。そこで、嫌気性アンモニア酸化法による窒素処理について、被処理水に含まれている有機物を予め除去ないし希釈する対策が検討されている。 Conventionally, there has been no established pure culture system for anaerobic ammonia oxidizing bacteria, and acclimatized sludge and sludge accumulating and cultivating seed sludge are mainly used in the anaerobic ammonia oxidizing method. Anaerobic ammonia-oxidizing bacteria have a very slow growth rate. Therefore, if the organic matter concentration in the water to be treated is high, heterotrophic microorganisms with a fast growth rate predominately grow and it becomes difficult for anaerobic ammonia-oxidizing bacteria to propagate. In view of this, measures for removing or diluting organic substances contained in water to be treated have been studied for nitrogen treatment by an anaerobic ammonia oxidation method.
　例えば、特許文献１には、廃水に含まれる有機物の濃度をメタン発酵によって減少させる処理、アンモニア態窒素をアナモックス細菌によって窒素ガスに変換する処理、及び、アンモニア態窒素の硝化及び硝酸態窒素・亜硝酸態窒素の脱窒を行う活性汚泥処理のいずれかを、廃水の有機物濃度に基づいて施す廃水処理方法が記載されている。 For example, Patent Document 1 discloses a process for reducing the concentration of organic substances contained in wastewater by methane fermentation, a process for converting ammonia nitrogen into nitrogen gas by anammox bacteria, and nitrification of ammonia nitrogen and nitrate nitrogen / suboxide. A wastewater treatment method is described in which any activated sludge treatment for denitrifying nitrate nitrogen is performed based on the organic matter concentration of the wastewater.
　また、特許文献２には、非凝集性細菌によって好気的に有機物を除去し、加圧浮上分離処理を用いて固液分離を行った後、アンモニア性窒素の一部を亜硝酸性窒素に酸化し、アンモニア性窒素と亜硝酸性窒素を含む非処理水を独立栄養性脱窒細菌により脱窒処理する排水処理方法が記載されている。 Patent Document 2 discloses that organic substances are removed aerobically by non-aggregating bacteria, solid-liquid separation is performed using a pressure flotation separation process, and then a part of ammonia nitrogen is converted to nitrite nitrogen. A waste water treatment method is described in which non-treated water containing oxidized nitrogen and nitrite nitrogen is denitrified by autotrophic denitrifying bacteria.
　また、特許文献３には、無酸素槽において廃水中の有機物を除去し、亜硝酸を生成させた後、亜硝酸とアンモニアから嫌気的に脱窒させた処理水を生成し、この処理水に残存するアンモニアを酸化させてから、無酸素槽に返送して循環させる廃水処理方法が記載されている。無酸素槽では、亜硝酸呼吸又は硝酸呼吸で廃水中の有機物が除去されている。 Further, in Patent Document 3, after removing organic substances in wastewater in an oxygen-free tank and generating nitrous acid, treated water that is anaerobically denitrified from nitrous acid and ammonia is produced, and this treated water is A wastewater treatment method is described in which the remaining ammonia is oxidized and then returned to the anoxic tank for circulation. In the anoxic tank, organic substances in the wastewater are removed by nitrite respiration or nitrate respiration.
特許第５８６２０８２号公報Japanese Patent No. 58602082 特許第５１８６４２０号公報Japanese Patent No. 5186420 特許第３８５８２７１号公報Japanese Patent No. 3858271
　嫌気性アンモニア酸化反応を利用して廃水の窒素処理を行うとき、嫌気性アンモニア酸化反応の前に活性汚泥処理等を行い、被処理水の有機物濃度を低下させておくと、有機物濃度が低くなった非処理水中で嫌気性アンモニア酸化細菌が繁殖し易くなるため、嫌気性アンモニア酸化反応の活性が安定し、比較的高い窒素除去率を得ることができる。 When performing nitrogen treatment of wastewater using anaerobic ammonia oxidation reaction, if the activated sludge treatment etc. is performed before the anaerobic ammonia oxidation reaction and the organic matter concentration in the treated water is lowered, the organic matter concentration will be lowered. In addition, since anaerobic ammonia oxidizing bacteria easily propagate in non-treated water, the activity of the anaerobic ammonia oxidizing reaction is stabilized, and a relatively high nitrogen removal rate can be obtained.
　しかし、特許文献１の方法では、事前に廃水のケルダール態窒素濃度やＣＯＤ／Ｎ比を分析する必要があるため、処理装置の運転が煩雑になるし、メタン発酵処理槽等の処理槽を併設した場合に、設備が大型化したり、設備コストが増大したりする。また、特許文献２の方法では、有機物を分解した後に、固液分離処理を行う必要があるため、処理装置の設備コストや運転コストが高くなるし、設備の小型化が妨げられる場合がある。 However, in the method of Patent Document 1, since it is necessary to analyze the Kjeldahl nitrogen concentration and COD / N ratio of wastewater in advance, the operation of the processing apparatus becomes complicated, and a processing tank such as a methane fermentation processing tank is also provided. In such a case, the equipment becomes larger or the equipment cost increases. Further, in the method of Patent Document 2, since it is necessary to perform a solid-liquid separation process after decomposing an organic substance, the equipment cost and operation cost of the processing apparatus are increased, and downsizing of the equipment may be hindered.
　特許文献３の方法では、無酸素槽における亜硝酸呼吸や硝酸呼吸で有機物が除去されるが、無酸素槽に返送される処理液の亜硝酸濃度や硝酸濃度が低下した場合に、有機物の分解が不十分になる虞がある。無酸素槽に返送される処理液は、亜硝酸濃度や硝酸濃度が硝化率や窒素除去率に左右されるため、原水の有機物濃度ないしＣ／Ｎ比が高い場合等に、有機物を処理しきれない可能性がある。 In the method of Patent Document 3, organic substances are removed by nitrous acid respiration and nitric acid respiration in an anaerobic tank, but when the nitrous acid concentration and nitric acid concentration of the treatment liquid returned to the anoxic tank are reduced, the decomposition of organic substances May be insufficient. The treatment liquid returned to the oxygen-free tank can completely treat organic matter when the organic matter concentration or the C / N ratio of the raw water is high because the nitrite concentration and nitric acid concentration depend on the nitrification rate and nitrogen removal rate. There is no possibility.
　そこで、本発明は、窒素成分及び有機物を含む廃水を低コストで効率的に処理する窒素処理方法を提供することを目的とする。 Therefore, an object of the present invention is to provide a nitrogen treatment method for efficiently treating wastewater containing nitrogen components and organic substances at low cost.
　前記課題を解決するために本発明に係る窒素処理方法は、廃水に含まれる窒素成分を脱窒する窒素処理方法であって、被処理水に含まれるアンモニア性窒素と亜硝酸性窒素とを微生物汚泥によって分子状窒素に変換する嫌気性アンモニア酸化処理工程を含み、前記嫌気性アンモニア酸化処理工程において、前記微生物汚泥が固定化されている充填材が保持された固定床型リアクタを用いて前記被処理水を処理する。 In order to solve the above-mentioned problem, a nitrogen treatment method according to the present invention is a nitrogen treatment method for denitrifying nitrogen components contained in waste water, and is a microorganism that converts ammonia nitrogen and nitrite nitrogen contained in treated water into microorganisms. An anaerobic ammonia oxidation treatment step of converting to molecular nitrogen by sludge, and in the anaerobic ammonia oxidation treatment step, using the fixed bed reactor in which the filler to which the microbial sludge is immobilized is held. Treat the treated water.
　本発明によれば、窒素成分及び有機物を含む廃水を低コストで効率的に処理することができる。 According to the present invention, waste water containing nitrogen components and organic substances can be efficiently treated at low cost.
窒素処理に用いられる廃水処理装置の一例を示す模式図である。It is a schematic diagram which shows an example of the waste water treatment apparatus used for nitrogen treatment. 窒素処理に用いられる廃水処理装置の他の例を示す模式図である。It is a schematic diagram which shows the other example of the wastewater treatment apparatus used for nitrogen treatment.
　以下、本発明の一実施形態に係る窒素処理方法について、図を参照しながら説明する。なお、以下の各図において共通する構成については同一の符号を付して重複した説明を省略する。 Hereinafter, a nitrogen treatment method according to an embodiment of the present invention will be described with reference to the drawings. In addition, about the structure which is common in each following figure, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.
　本実施形態に係る窒素処理方法は、廃水（被処理水）に含まれる窒素成分を生物学的な処理により脱窒する方法に関する。この窒素処理方法は、被処理水に含まれるアンモニア性窒素と亜硝酸性窒素とを微生物汚泥によって分子状窒素に変換する嫌気性アンモニア酸化処理工程を少なくとも含んでいる。 The nitrogen treatment method according to this embodiment relates to a method of denitrifying nitrogen components contained in waste water (treated water) by biological treatment. This nitrogen treatment method includes at least an anaerobic ammonia oxidation treatment step of converting ammonia nitrogen and nitrite nitrogen contained in the water to be treated into molecular nitrogen by microbial sludge.
　本実施形態に係る窒素処理方法では、嫌気性アンモニア酸化処理工程において、微生物汚泥が固定化されている充填材が保持されている固定床型リアクタを用いて被処理水を処理する。固定床型リアクタによると、嫌気性アンモニア酸化細菌と従属栄養性微生物と、を処理槽内の異なる領域に、それぞれ繁殖させることができる。そのため、被処理水に窒素成分に加えて有機物が含まれていても、単槽で効率的に処理することができる。 In the nitrogen treatment method according to the present embodiment, in the anaerobic ammonia oxidation treatment step, the water to be treated is treated using a fixed bed reactor in which a filler to which microbial sludge is immobilized is held. According to the fixed bed reactor, anaerobic ammonia oxidizing bacteria and heterotrophic microorganisms can be propagated in different regions in the treatment tank. Therefore, even if the water to be treated contains an organic substance in addition to the nitrogen component, it can be treated efficiently in a single tank.
　図１は、窒素処理に用いられる廃水処理装置の一例を示す模式図である。
　本実施形態に係る窒素処理方法は、図１に示されるような廃水処理装置１００を使用して実施することができる。図１に示す廃水処理装置１００は、固定床型リアクタである嫌気性アンモニア酸化槽１と、微生物汚泥が固定化されている充填材２と、供給ポンプ３と、ｐＨ調整装置４と、アンモニア酸化槽５と、微生物汚泥６と、散気装置７と、処理水槽８と、洗浄用ポンプ９と、を備えている。 FIG. 1 is a schematic diagram illustrating an example of a wastewater treatment apparatus used for nitrogen treatment.
The nitrogen treatment method according to this embodiment can be carried out using a wastewater treatment apparatus 100 as shown in FIG. A wastewater treatment apparatus 100 shown in FIG. 1 includes an anaerobic ammonia oxidation tank 1 that is a fixed bed reactor, a filler 2 on which microbial sludge is immobilized, a supply pump 3, a pH adjuster 4, and ammonia oxidation. A tank 5, a microorganism sludge 6, an air diffuser 7, a treated water tank 8, and a cleaning pump 9 are provided.
　廃水処理装置１００は、窒素成分を含む廃水（被処理水）を嫌気性アンモニア酸化法によって窒素処理する装置であり、亜硝酸型硝化と嫌気性アンモニア酸化とを個別の反応槽で行う二槽式とされている。廃水処理装置１００は、嫌気性アンモニア酸化処理を行う嫌気性アンモニア酸化槽１が固定床型リアクタであるため、嫌気性である嫌気性アンモニア酸化細菌と好気性である従属栄養性微生物とを、処理槽内の異なる領域でそれぞれ繁殖させて、有機物の分解と嫌気性アンモニア酸化とを単槽で行える。 The wastewater treatment apparatus 100 is an apparatus for treating nitrogen-containing wastewater (treated water) with an anaerobic ammonia oxidation method, and is a two-tank type that performs nitrite-type nitrification and anaerobic ammonia oxidation in separate reaction tanks. It is said that. Since the anaerobic ammonia oxidation tank 1 that performs anaerobic ammonia oxidation treatment is a fixed bed reactor, the wastewater treatment apparatus 100 treats anaerobic anaerobic ammonia oxidizing bacteria and aerobic heterotrophic microorganisms. It can be propagated in different areas in the tank to decompose organic matter and anaerobic ammonia oxidation in a single tank.
　被処理水に有機物が含まれている場合、増殖速度が速い従属栄養性微生物が優占増殖し、増殖速度が遅い嫌気性アンモニア酸化細菌が繁殖し難くなるため、嫌気性アンモニア酸化活性が低下ないし不安定化する傾向がある。これに対し、固定床型リアクタによると、被処理水に含まれる有機物によって、処理槽内の上流側に従属栄養性微生物が繁殖し、有機物濃度が低くなる下流側に嫌気性アンモニア酸化細菌が繁殖するため、被処理水に有機物が含まれていても、処理槽内の下流側で、高活性で安定な嫌気性アンモニア酸化活性を得ることができる。 When organic matter is contained in the water to be treated, the anaerobic ammonia oxidizing activity does not decrease because heterotrophic microorganisms with a fast growth rate predominately grow and anaerobic ammonia oxidizing bacteria with a slow growth rate are difficult to propagate. There is a tendency to destabilize. On the other hand, according to the fixed bed reactor, heterotrophic microorganisms propagate on the upstream side in the treatment tank, and anaerobic ammonia-oxidizing bacteria propagate on the downstream side where the organic matter concentration is low, due to the organic matter contained in the water to be treated. Therefore, even if the water to be treated contains an organic substance, highly active and stable anaerobic ammonia oxidation activity can be obtained on the downstream side in the treatment tank.
　被処理水としては、例えば、下水処理施設、半導体工場、金属精錬所、薬品製造施設等の事業場から排出される廃水が挙げられる。廃水は、アンモニア性窒素や有機物の他に、リン、炭素、重金属類等の栄養塩を含んでいてもよい。また、廃水は、アンモニア酸化槽１で行う硝化処理の前に、活性汚泥処理、従属栄養性脱窒細菌による脱窒処理、脱リン処理等が行われてもよい。 Examples of treated water include wastewater discharged from business sites such as sewage treatment facilities, semiconductor factories, metal smelters, and chemical manufacturing facilities. The waste water may contain nutrient salts such as phosphorus, carbon, and heavy metals in addition to ammonia nitrogen and organic matter. In addition, the wastewater may be subjected to activated sludge treatment, denitrification treatment with heterotrophic denitrification bacteria, dephosphorization treatment, and the like before the nitrification treatment performed in the ammonia oxidation tank 1.
　嫌気性アンモニア酸化槽１は、微生物汚泥が固定化されている充填材２が保持された固定床型リアクタとされている。固定床を形成する充填材２は、筒型の処理槽内に保持され、充填材２同士の隙間に被処理水が通流する。充填材２には、嫌気性アンモニア酸化細菌を含む微生物汚泥や、従属栄養性微生物を含む微生物汚泥が固定化される。 The anaerobic ammonia oxidation tank 1 is a fixed bed reactor in which a filler 2 on which microbial sludge is immobilized is held. The filler 2 forming the fixed bed is held in a cylindrical treatment tank, and the water to be treated flows through the gap between the fillers 2. A microbial sludge containing anaerobic ammonia-oxidizing bacteria and a microbial sludge containing heterotrophic microorganisms are immobilized on the filler 2.
　嫌気性アンモニア酸化槽１は、図１において、処理槽の上部に流入口、処理槽の下部に流出口を有しており、被処理水を下向流として流す筒形の固定床型リアクタとされている。流入口には、供給ポンプ３とｐＨ調整装置４を備えた配管を介して、アンモニア酸化槽５が接続されている。アンモニア酸化槽５で処理された処理水は、必要に応じてｐＨ調整され、供給ポンプ３によって嫌気性アンモニア酸化槽１に導入される。 1, the anaerobic ammonia oxidation tank 1 has an inlet at the upper part of the treatment tank and an outlet at the lower part of the treatment tank, and has a cylindrical fixed bed reactor for flowing the treated water as a downward flow. Has been. An ammonia oxidation tank 5 is connected to the inlet through a pipe provided with a supply pump 3 and a pH adjusting device 4. The treated water treated in the ammonia oxidation tank 5 is adjusted in pH as necessary, and is introduced into the anaerobic ammonia oxidation tank 1 by the supply pump 3.
　アンモニア酸化槽５は、被処理水に含まれているアンモニア性窒素を亜硝酸性窒素に酸化する亜硝酸型の硝化処理を行う処理槽である。アンモニア酸化槽５には、被処理水を生物学的に処理するために微生物汚泥６が保持される。また、アンモニア酸化槽５には、被処理水を曝気するための散気装置７が備えられる。 The ammonia oxidation tank 5 is a treatment tank that performs a nitrite type nitrification treatment that oxidizes ammonia nitrogen contained in water to be treated into nitrite nitrogen. The ammonia oxidation tank 5 holds microbial sludge 6 for biologically treating the water to be treated. Further, the ammonia oxidation tank 5 is provided with an air diffuser 7 for aeration of the water to be treated.
　微生物汚泥６は、細菌や原生生物等を含む汚泥であり、硝化細菌群を含んでいる。通常、硝化細菌群は、ニトロソモナス（Nitrosomonas）属、ニトロソコッカス（Nitrosococcus）属、ニトロソスピラ（Nitrosospira）属、ニトロソロブス（Nitrosolobus）属等に分類されるアンモニア酸化細菌（ＡＯＢ）と、ニトロバクター（Nitrobactor）属、ニトロスピナ（Nitrospina）属、ニトロコッカス（Nitrococcus）属、ニトロスピラ（Nitrospira）属等に分類される亜硝酸酸化細菌（ＮＯＢ）との混成である。 The microbial sludge 6 is a sludge containing bacteria, protists, etc., and contains a group of nitrifying bacteria. Usually, the nitrifying bacteria group includes ammonia-oxidizing bacteria (AOB) classified into genus Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosolobus, etc., and Nitrobactor. ), Nitrospina, Nitrococcus, Nitrospira and the like, and nitrous oxide bacteria (NOB).
　微生物汚泥６は、図１において、流動床担体に固定化されている。但し、アンモニア酸化槽５で用いる微生物汚泥は、担体の内部に包括固定化されている状態、担体の表面に包括固定化されている状態、担体に付着固定化されている状態、自己造粒によるグラニュールを形成している状態、及び、水中に浮遊した浮遊汚泥の状態のうち、いずれの状態であってもよい。また、固定化された微生物汚泥は、固定床、流動床及び移動床のいずれの形態で用いられてもよい。 The microbial sludge 6 is fixed to the fluidized bed carrier in FIG. However, the microbial sludge used in the ammonia oxidation tank 5 is in a state of being entrapped and immobilized inside the carrier, in a state of being entrapped and immobilized on the surface of the carrier, in a state of being adhered and immobilized on the carrier, by self-granulation Any of a state in which granules are formed and a state of floating sludge suspended in water may be used. Moreover, the immobilized microbial sludge may be used in any form of a fixed bed, a fluidized bed, and a moving bed.
　担体の材料としては、モノ（メタ）アクリレート類、ジ（メタ）アクリレート類、トリ（メタ）アクリレート類、テトラ（メタ）アクリレート類、ウレタン（メタ）アクリレート類、エポキシ（メタ）アクリレート類、ポリビニルアルコール、ビニロン、ポリエチレングリコール、ポリプロピレングリコール、アクリルアミド、ポリエチレン、ポリプロピレン、エチレン酢酸ビニル共重合体、ポリ塩化ビニル、アラミドやナイロン等のポリアミド、ポリエステル、レーヨン、ガラス、活性炭等の適宜の材料を使用することができる。 Carrier materials include mono (meth) acrylates, di (meth) acrylates, tri (meth) acrylates, tetra (meth) acrylates, urethane (meth) acrylates, epoxy (meth) acrylates, polyvinyl alcohol , Vinylon, polyethylene glycol, polypropylene glycol, acrylamide, polyethylene, polypropylene, ethylene vinyl acetate copolymer, polyvinyl chloride, polyamides such as aramid and nylon, polyester, rayon, glass, activated carbon, etc. it can.
　担体の形状は、立方体状、直方体状、板状、球状、円盤状、円筒状、多孔質状、スポンジ状、繊維状、布状、コイン状、レンコン状、菊花状等の適宜の形状とすることができる。担体の大きさは、特に制限されるものではなく、例えば、３ｍｍ角等とすることができる。 The shape of the carrier is an appropriate shape such as a cubic shape, a rectangular parallelepiped shape, a plate shape, a spherical shape, a disc shape, a cylindrical shape, a porous shape, a sponge shape, a fiber shape, a cloth shape, a coin shape, a lotus shape, or a chrysanthemum shape. be able to. The size of the carrier is not particularly limited, and can be, for example, 3 mm square.
　散気装置７は、例えば、気泡を発生するディフューザや散気管、空気を供給する送風機、空気を圧縮するコンプレッサ、送風機からディフューザや散気管に空気を送る送気管等によって構成される。被処理水についての曝気量は、一定に制御してもよいし、アンモニア性窒素の濃度、亜硝酸性窒素の濃度等に応じて、目的の硝化率となるように可変制御してもよい。 The air diffuser 7 includes, for example, a diffuser that generates bubbles and a diffuser pipe, a blower that supplies air, a compressor that compresses air, an air supply pipe that sends air from the blower to the diffuser and the diffuser pipe, and the like. The aeration amount of the water to be treated may be controlled to be constant, or may be variably controlled so as to achieve a target nitrification rate according to the concentration of ammonia nitrogen, the concentration of nitrite nitrogen, or the like.
　ｐＨ調整装置４は、嫌気性アンモニア酸化処理される被処理水のｐＨを調整するために備えられる。ｐＨ調整装置４は、例えば、ｐＨ調整剤を貯留するｐＨ調整剤タンク、ｐＨ調整剤を被処理水に供給する薬注ポンプ等によって構成される。ｐＨ調整剤としては、例えば、炭酸水素ナトリウム、水酸化ナトリウム等のアルカリ性ｐＨ調整剤を用いることができる。アンモニア酸化槽５で処理された処理水は、酸性化しているｐＨが中性付近に調整される。 The pH adjusting device 4 is provided for adjusting the pH of the water to be treated that is subjected to the anaerobic ammonia oxidation treatment. The pH adjusting device 4 includes, for example, a pH adjusting agent tank that stores the pH adjusting agent, a chemical injection pump that supplies the pH adjusting agent to the water to be treated, and the like. As a pH adjuster, alkaline pH adjusters, such as sodium hydrogencarbonate and sodium hydroxide, can be used, for example. The treated water treated in the ammonia oxidation tank 5 has an acidified pH adjusted to be near neutral.
　嫌気性アンモニア酸化槽１は、被処理水に含まれる有機物を分解する有機物処理と、被処理水に含まれるアンモニア性窒素と亜硝酸性窒素を嫌気性アンモニア酸化反応によって共脱窒する嫌気性アンモニア酸化処理とを行う。有機物処理は、処理槽内の上流側（流入口側）の充填材２に保持される従属栄養性微生物によって行われる。また、嫌気性アンモニア酸化処理は、処理槽内の下流側（流出側）の充填材２に保持される嫌気性アンモニア酸化細菌によって行われる。 The anaerobic ammonia oxidation tank 1 is an anaerobic ammonia that decomposes organic substances contained in the water to be treated and co-denitrifies ammonia nitrogen and nitrite nitrogen contained in the water to be treated by an anaerobic ammonia oxidation reaction. And oxidation treatment. The organic matter treatment is performed by heterotrophic microorganisms held in the filler 2 on the upstream side (inlet side) in the treatment tank. In addition, the anaerobic ammonia oxidation treatment is performed by anaerobic ammonia oxidizing bacteria held in the downstream side (outflow side) filler 2 in the treatment tank.
　嫌気性アンモニア酸化槽１は、固定床型リアクタであるため、有機物を含む被処理水が流入すると、処理槽内の上流側で有機物濃度が高くなり、上流側に位置する充填材２上で、従属栄養性微生物が繁殖する。そして、被処理水に含まれる有機物や溶存酸素が従属栄養性微生物によって消費され、有機物濃度や溶存酸素濃度が低下した被処理水が下流側に流れる。そのため、被処理水に有機物や溶存酸素が含まれていたとしても、処理槽内の下流側に位置する充填材２上で、嫌気性アンモニア酸化細菌を確実に増殖させることができる。 Since the anaerobic ammonia oxidation tank 1 is a fixed bed reactor, when treated water containing organic substances flows in, the organic substance concentration increases on the upstream side in the treatment tank, and on the filler 2 located on the upstream side, Heterotrophic microorganisms breed. And the organic matter and dissolved oxygen which are contained in to-be-processed water are consumed by the heterotrophic microorganism, and the to-be-processed water which the organic matter density | concentration and dissolved oxygen concentration fell flows downstream. Therefore, even if organic matter and dissolved oxygen are contained in the water to be treated, anaerobic ammonia-oxidizing bacteria can be reliably grown on the filler 2 located on the downstream side in the treatment tank.
　固定床型リアクタで用いる微生物汚泥は、担体の内部に包括固定化されている状態、担体の表面に包括固定化されている状態、担体に付着固定化されている状態、又は、自己造粒によるグラニュールを形成している状態であることが好ましい。すなわち、固定床の充填材２として、担体ないしグラニュールを用いることができる。このような充填材２を処理槽に充填すると、充填材２自体が形成する充填層によって、被処理水が混合拡散し難くなる。そのため、固定床型リアクタ内を仕切る等しなくとも、有機物や溶存酸素の濃度分極を容易に生じさせることができる。 Microbial sludge used in a fixed bed reactor is in a state of being entrapped and immobilized inside the carrier, in a state of being entrapped and immobilized on the surface of the carrier, in a state of being adhered and immobilized on the carrier, or by self-granulation It is preferable that the granules are formed. That is, a carrier or granule can be used as the filler 2 for the fixed bed. When such a filler 2 is filled in the treatment tank, the water to be treated becomes difficult to mix and diffuse by the filling layer formed by the filler 2 itself. Therefore, concentration polarization of organic matter and dissolved oxygen can be easily generated without partitioning the fixed bed reactor.
　固定床型リアクタにおいて、被処理水の通水方向に有機物や溶存酸素の濃度分極が生じると、嫌気性アンモニア酸化細菌と従属栄養性微生物のそれぞれの生息域が、処理槽内の上流側と下流側とに分離される。被処理水に有機物や溶存酸素が含まれていたとしても、処理槽内の上流側の従属栄養性微生物が有機物や溶存酸素を消費し、処理槽内の下流側で嫌気性アンモニア酸化細菌が繁殖するため、高活性で安定な嫌気性アンモニア酸化活性を得ることができる。 In a fixed-bed reactor, when concentration polarization of organic matter and dissolved oxygen occurs in the direction of water to be treated, the habitats of anaerobic ammonia-oxidizing bacteria and heterotrophic microorganisms are located upstream and downstream in the treatment tank. Separated into side. Even if the treated water contains organic matter and dissolved oxygen, heterotrophic microorganisms upstream in the treatment tank consume organic matter and dissolved oxygen, and anaerobic ammonia-oxidizing bacteria propagate on the downstream side in the treatment tank Therefore, highly active and stable anaerobic ammonia oxidation activity can be obtained.
　担体の充填材２は、立方体状、直方体状、板状、球状、円盤状、円筒状、多孔質状、スポンジ状、繊維状、布状、コイン状、レンコン状、菊花状等の適宜の形状とすることができる。担体としては、微生物汚泥の保持量や比表面積が大きい点、固定床型リアクタへの充填が容易な点等から、立方体状、直方体状等の樹脂ペレットの担体が特に好ましく用いられる。担体の大きさは、特に制限されるものではなく、例えば、３ｍｍ角等とすることができる。担体の材料は、アンモニア酸化槽１の担体と同様にすることができる。 The carrier filler 2 has an appropriate shape such as a cubic shape, a rectangular parallelepiped shape, a plate shape, a spherical shape, a disc shape, a cylindrical shape, a porous shape, a sponge shape, a fiber shape, a cloth shape, a coin shape, a lotus shape, and a chrysanthemum shape. It can be. As the support, a resin pellet support such as a cubic shape or a rectangular parallelepiped shape is particularly preferably used from the viewpoint that the retained amount of microbial sludge and the specific surface area are large and the fixed bed reactor can be easily filled. The size of the carrier is not particularly limited, and can be, for example, 3 mm square. The material of the carrier can be the same as that of the ammonia oxidation tank 1.
　担体の充填材２は、比重が少なくとも１ｇ／ｃｍ３未満であり、沈降性であることが好ましい。充填材２が沈降性の担体であると、固定床型リアクタに直接充填したとき、被処理水が通水されても流動し難くなる。そのため、嫌気性アンモニア酸化細菌と従属栄養性微生物のそれぞれの生息域を、処理槽内の上流側と下流側とに明確に分離して、高活性で安定な嫌気性アンモニア酸化活性を得ることができる。 The carrier filler 2 preferably has a specific gravity of at least 1 g / cm 3 and is sedimentable. When the filler 2 is a sedimentary carrier, when the fixed bed reactor is directly filled, it becomes difficult to flow even if the water to be treated is passed. Therefore, it is possible to clearly separate the habitats of anaerobic ammonia oxidizing bacteria and heterotrophic microorganisms into upstream and downstream sides in the treatment tank to obtain highly active and stable anaerobic ammonia oxidizing activity. it can.
　充填材２の充填率は、充填層当たり、好ましくは６０％以上、より好ましくは７０％以上、更に好ましくは８０％以上である。また、充填率は、好ましくは９０％以下である。なお、充填層の容積としては、被処理水の通水方向の有効高さで計算した見かけ容積を用いる。このような高い充填率であると、充填材２として充填された担体ないしグラニュールで被処理水が攪拌され難くなる。そのため、嫌気性アンモニア酸化細菌と従属栄養性微生物のそれぞれの生息域を被処理水の通水方向に分離して、高活性で安定な嫌気性アンモニア酸化活性を得ることができる。また、充填材２の総表面積が大きくなるため、高い脱窒速度を得ることができる。 The filling rate of the filler 2 is preferably 60% or more, more preferably 70% or more, and further preferably 80% or more per packed bed. The filling rate is preferably 90% or less. In addition, as the volume of the packed bed, the apparent volume calculated by the effective height in the direction of water flow of the water to be treated is used. With such a high filling rate, it becomes difficult for the water to be treated to be stirred by the carrier or granule filled as the filler 2. Therefore, it is possible to obtain a highly active and stable anaerobic ammonia oxidizing activity by separating the habitats of the anaerobic ammonia oxidizing bacteria and the heterotrophic microorganisms in the direction of water flow. Moreover, since the total surface area of the filler 2 becomes large, a high denitrification rate can be obtained.
　充填材２としては、嫌気性アンモニア酸化細菌と従属栄養性微生物とを固定化した一種を固定床型リアクタに保持してもよいし、嫌気性アンモニア酸化細菌を固定化した充填材２と、従属栄養性微生物を固定化した充填材２とを、被処理水の通水方向に分けて固定床型リアクタに保持してもよい。一種の充填材２を一括して収容する場合、担体ないしグラニュールの調製は容易になるが、長時間の馴養が必要になる。これに対し、従属栄養性微生物を保持する充填材２を上流側に配置し、嫌気性アンモニア酸化細菌を保持する充填材２を下流側に配置すると、短い馴養時間で生息域を分離することができる。 As the filler 2, one kind of immobilized anaerobic ammonia oxidizing bacteria and heterotrophic microorganisms may be held in a fixed bed reactor, or the filler 2 immobilized with anaerobic ammonia oxidizing bacteria, The filler 2 on which the nutritional microorganisms are immobilized may be held in a fixed bed type reactor in the direction of water flow of the water to be treated. When a kind of filler 2 is accommodated in a lump, it is easy to prepare a carrier or granule, but it is necessary to acclimatize for a long time. On the other hand, if the filler 2 holding heterotrophic microorganisms is arranged upstream and the filler 2 holding anaerobic ammonia-oxidizing bacteria is arranged downstream, the habitat can be separated in a short acclimatization time. it can.
　固定床型リアクタには、充填材２である担体ないしグラニュールを直接収容してもよいし、開孔を有する容器に収容し、その容器を固定床型リアクタに投入してもよい。容器としては、例えば、ストレーナ型、コランダ型等のざる状容器を用いることができる。充填材２を容器に収容する場合、充填材２同士が接触する程度に密に充填してもよいし、充填材２同士が接触し難い疎な状態に収容してもよい。容器当たりの充填率が低いと、容器内で充填材２が流動できるため、嫌気性アンモニア酸化細菌と従属栄養性微生物のそれぞれの生息域が分離し難くなるが、処理槽内の閉塞が防止される。 In the fixed bed type reactor, the carrier or granule as the filler 2 may be directly stored, or may be stored in a container having an opening, and the container may be charged into the fixed bed type reactor. As the container, for example, a strainer type, a colander type or the like can be used. When the filler 2 is accommodated in the container, it may be packed so densely that the fillers 2 are in contact with each other, or may be accommodated in a sparse state where the fillers 2 are not easily in contact with each other. If the filling rate per container is low, the filler 2 can flow in the container, so that it is difficult to separate the habitat of anaerobic ammonia oxidizing bacteria and heterotrophic microorganisms, but blockage in the treatment tank is prevented. The
　固定床型リアクタは、ピストンフロー式の処理槽であることが好ましい。ピストンフロー式であると、完全混合式の場合と比較して、被処理水が拡散混合し難くなる。均一性が高い線速度で被処理水が流れ、有機物や溶存酸素の濃度分極が生じ易くなるため、嫌気性アンモニア酸化細菌と従属栄養性微生物のそれぞれの生息域を、処理槽内の上流側と下流側とに明確に分離して、高活性で安定な嫌気性アンモニア酸化活性を得ることができる。 The fixed bed reactor is preferably a piston flow type treatment tank. If it is a piston flow type, compared with the case of a complete mixing type, to-be-processed water becomes difficult to carry out a diffusive mixing. Because the treated water flows at a highly uniform linear velocity and concentration polarization of organic matter and dissolved oxygen is likely to occur, each habitat of anaerobic ammonia-oxidizing bacteria and heterotrophic microorganisms can be separated from the upstream side of the treatment tank. It is possible to obtain a highly active and stable anaerobic ammonia oxidation activity by clearly separating into the downstream side.
　固定床型リアクタは、処理槽内が、目皿、仕切板、蛇籠等によって、複数の区画に仕切られていてもよい。処理槽内が被処理水の通水方向に仕切られていると、被処理水が通水されても充填材２の位置が大きく変化しないため、嫌気性アンモニア酸化細菌と従属栄養性微生物のそれぞれの生息域を明確に分離して、高活性で安定な嫌気性アンモニア酸化活性を得ることができる。また、上流側の区画の充填材２と下流側の区画の充填材２とが混合しなくなるため、攪拌装置による高速攪拌が可能になり、高い脱窒速度を得ることができる。 In the fixed bed reactor, the inside of the processing tank may be partitioned into a plurality of compartments by an eye plate, a partition plate, a gabion or the like. If the inside of the treatment tank is partitioned in the direction of water to be treated, the position of the filler 2 does not change greatly even if the water to be treated is passed, so that each of anaerobic ammonia oxidizing bacteria and heterotrophic microorganisms It is possible to obtain a highly active and stable anaerobic ammonia oxidation activity by clearly separating the habitat. In addition, since the filler 2 in the upstream compartment and the filler 2 in the downstream compartment are not mixed, high-speed agitation with a stirrer is possible, and a high denitrification rate can be obtained.
　処理水槽８は、嫌気性アンモニア酸化槽１で処理された処理水を受けるために備えられる。嫌気性アンモニア酸化槽６で処理された処理水の一部は、処理水槽８に移送されて一時的に貯留される。そして、処理水槽８の処理水は、任意の時期に、洗浄用ポンプ９で嫌気性アンモニア酸化槽６に返送される。洗浄用ポンプ９は、供給ポンプ３よりも高圧に昇圧した処理水を、充填材２の下方に開口した流入口から固定床型リアクタ内に流入させて、充填材２を物理洗浄することができる。 The treated water tank 8 is provided for receiving treated water treated in the anaerobic ammonia oxidation tank 1. A part of the treated water treated in the anaerobic ammonia oxidation tank 6 is transferred to the treated water tank 8 and temporarily stored. Then, the treated water in the treated water tank 8 is returned to the anaerobic ammonia oxidation tank 6 by the cleaning pump 9 at an arbitrary time. The cleaning pump 9 can physically clean the filler 2 by flowing treated water whose pressure is higher than that of the supply pump 3 into the fixed bed reactor from the inlet opening below the filler 2. .
　次に、本実施形態に係る窒素処理方法の一例について、廃水処理装置１００を使用した嫌気性アンモニア酸化法による窒素処理を例として具体的に説明する。 Next, an example of the nitrogen treatment method according to the present embodiment will be specifically described by taking nitrogen treatment by an anaerobic ammonia oxidation method using the wastewater treatment apparatus 100 as an example.
　嫌気性アンモニア酸化法による窒素処理は、被処理水に含まれるアンモニア性窒素を微生物汚泥によって酸化して亜硝酸性窒素を生成する硝化処理工程と、硝化処理工程において処理された被処理水に含まれるアンモニア性窒素と亜硝酸性窒素とを嫌気性アンモニア酸化反応によって分子状窒素に変換する嫌気性アンモニア酸化処理工程と、を含む方法によって行うことができる。 Nitrogen treatment by the anaerobic ammonia oxidation method is included in the nitrification process that generates ammonia and nitrite nitrogen by oxidizing ammonia nitrogen contained in the treated water with microbial sludge, and is included in the treated water treated in the nitrification process. An anaerobic ammonia oxidation treatment step of converting ammonia nitrogen and nitrite nitrogen to molecular nitrogen by an anaerobic ammonia oxidation reaction.
　一般に、嫌気性アンモニア酸化処理は、流動床型の処理槽を使用した完全混合型の流れ場で行われることが多い。従属栄養性微生物の増殖速度は、嫌気性アンモニア酸化細菌よりも速いため、被処理水に有機物が含まれていると、処理槽内で従属栄養性微生物が優占増殖し、嫌気性アンモニア酸化活性が十分に得られなかったり、嫌気性アンモニア酸化処理中に不安定化して、窒素除去率が安定しなかったりする。 In general, anaerobic ammonia oxidation treatment is often performed in a completely mixed flow field using a fluidized bed type treatment tank. Since the growth rate of heterotrophic microorganisms is faster than that of anaerobic ammonia oxidizing bacteria, if the treated water contains organic matter, the heterotrophic microorganisms predominately grow in the treatment tank and anaerobic ammonia oxidizing activity May not be sufficiently obtained, or may become unstable during anaerobic ammonia oxidation treatment, and the nitrogen removal rate may not be stable.
　従来、嫌気性アンモニア酸化法による窒素処理に際しては、原水に含まれる有機物を処理する目的で、予め活性汚泥処理等が行われている。しかし、活性汚泥処理等を必須の前処理として行う方法では、設備が大型化したり、設備コストが増大したりするため、嫌気性アンモニア酸化法による有利性が損なわれる場合がある。 Conventionally, in nitrogen treatment by an anaerobic ammonia oxidation method, activated sludge treatment or the like has been performed in advance for the purpose of treating organic substances contained in raw water. However, in the method in which the activated sludge treatment or the like is performed as an essential pretreatment, the equipment becomes larger and the equipment cost increases, so that the advantages of the anaerobic ammonia oxidation method may be impaired.
　また、嫌気性アンモニア酸化細菌の増殖は溶存酸素によって阻害されるところ、活性汚泥処理においては曝気が行われるため、嫌気性アンモニア酸化処理の前に、溶存酸素を脱気しておく必要がある。脱気処理は、窒素ガス等の散気、被処理水の攪拌等による強制脱気や、自然脱気によって行うことができるが、個別の調整槽等を用いて脱気処理を行う方法では、設備が複雑化したり、前処理が長時間化したりする。 Also, the growth of anaerobic ammonia oxidizing bacteria is inhibited by dissolved oxygen. Since aeration is performed in the activated sludge treatment, it is necessary to deaerate the dissolved oxygen before the anaerobic ammonia oxidation treatment. The deaeration treatment can be performed by aeration such as nitrogen gas, forced deaeration by stirring water to be treated, and natural deaeration, but in the method of performing the deaeration treatment using an individual adjustment tank, Equipment becomes complicated and pretreatment takes a long time.
　これに対し、本実施形態に係る窒素処理方法では、嫌気性アンモニア酸化処理工程において、微生物汚泥が固定化されている充填材が充填された固定床型リアクタを用いて被処理水を処理するため、嫌気性アンモニア酸化処理の効率を原水の有機物濃度や溶存酸素濃度に影響され難くすることができる。 On the other hand, in the nitrogen treatment method according to the present embodiment, in the anaerobic ammonia oxidation treatment process, water to be treated is treated using a fixed bed reactor filled with a filler in which microbial sludge is immobilized. The efficiency of the anaerobic ammonia oxidation treatment can be made less susceptible to the organic matter concentration and dissolved oxygen concentration of the raw water.
　被処理水の全窒素の濃度、及び、アンモニア性窒素の濃度は、嫌気性アンモニア酸化活性の阻害を避ける観点からは、１ｍｇ／Ｌ以上１０００ｍｇ／Ｌ以下であることが好ましい。また、固定床型リアクタの有効性を極大化する観点からは、本来高い窒素除去率を達成するのが困難な低濃度の範囲がより好ましい。具体的には、被処理水の全窒素の濃度、及び、アンモニア性窒素の濃度は、１０ｍｇ／Ｌ以上１５０ｍｇ／Ｌ以下であることがより好ましい。 The total nitrogen concentration of the water to be treated and the ammonia nitrogen concentration are preferably 1 mg / L or more and 1000 mg / L or less from the viewpoint of avoiding the inhibition of anaerobic ammonia oxidation activity. Further, from the viewpoint of maximizing the effectiveness of the fixed bed reactor, a low concentration range in which it is inherently difficult to achieve a high nitrogen removal rate is more preferable. Specifically, the concentration of total nitrogen and the concentration of ammoniacal nitrogen in the water to be treated are more preferably 10 mg / L or more and 150 mg / L or less.
　被処理水は、全窒素の濃度やアンモニア性窒素の濃度が高い場合、嫌気性アンモニア酸化処理工程の前に、嫌気性アンモニア酸化処理された処理水等で、予め希釈することができる。また、微生物汚泥を馴養する必要がある立ち上げ時には、はじめに、希釈した被処理水を流入させてから、徐々に全窒素の濃度やアンモニア性窒素の濃度を高くして通水することができる。 If the concentration of total nitrogen or ammonia nitrogen is high, the water to be treated can be diluted in advance with anaerobic ammonia oxidation treated water or the like before the anaerobic ammonia oxidation treatment step. Moreover, when it is necessary to acclimate the microbial sludge, first, after the diluted water to be treated is introduced, the water can be passed with gradually increasing the concentration of total nitrogen and ammonia nitrogen.
　硝化処理工程は、硝化細菌群を保持するアンモニア酸化槽５において、好気条件下、必要に応じてアルカリの添加やｐＨの調整を実施しながら行う。被処理水の水温は、１０℃以上４０℃以下であることが好ましい。また、被処理水のｐＨは、ｐＨ６以上ｐＨ１０以下であることが好ましい。被処理水のｐＨは、アンモニア性窒素の亜硝酸化が進むほど酸性側に低下していく。 The nitrification treatment step is performed in the ammonia oxidation tank 5 holding the nitrifying bacteria group while performing alkali addition and pH adjustment as necessary under aerobic conditions. The water temperature of the water to be treated is preferably 10 ° C. or higher and 40 ° C. or lower. Moreover, it is preferable that pH of to-be-processed water is pH6 or more and pH10 or less. The pH of the water to be treated decreases to the acidic side as the nitritation of ammoniacal nitrogen proceeds.
　硝化処理される被処理水は、アンモニア性窒素の濃度と亜硝酸性窒素の濃度との比が１：１～１：１．５となる溶存酸素濃度に調整されることが好ましい。通常、溶存酸素濃度を０．５ｍｇ／Ｌ以上４．０ｍｇ／Ｌ以下の範囲で加減すると、亜硝酸型硝化の硝化率が適切な範囲になる。適切な濃度比に調整すると、ワンパス式の処理の場合に、嫌気性アンモニア酸化反応が効率的に進むため、高い窒素除去率を得ることができる。 The water to be treated for nitrification is preferably adjusted to a dissolved oxygen concentration such that the ratio of the ammonia nitrogen concentration to the nitrite nitrogen concentration is 1: 1 to 1: 1.5. Usually, when the dissolved oxygen concentration is adjusted within a range of 0.5 mg / L or more and 4.0 mg / L or less, the nitrification rate of the nitrite type nitrification becomes an appropriate range. When adjusted to an appropriate concentration ratio, an anaerobic ammonia oxidation reaction proceeds efficiently in the case of a one-pass process, so that a high nitrogen removal rate can be obtained.
　嫌気性アンモニア酸化処理工程は、嫌気性アンモニア酸化細菌と従属栄養性微生物を保持する嫌気性アンモニア酸化槽１において、無酸素条件下、必要に応じてｐＨの調整を実施して行う。被処理水のｐＨは、好ましくはｐＨ６．５以上ｐＨ９以下、より好ましくはｐＨ７以上ｐＨ８．２以下である。また、被処理水の水温は、好ましくは１０℃以上４０℃以下、より好ましくは１５℃以上３７℃以下である。 The anaerobic ammonia oxidation treatment step is performed by adjusting the pH as necessary under anoxic conditions in the anaerobic ammonia oxidation tank 1 holding anaerobic ammonia oxidizing bacteria and heterotrophic microorganisms. The pH of the water to be treated is preferably pH 6.5 or more and pH 9 or less, more preferably pH 7 or more and pH 8.2 or less. Moreover, the water temperature of to-be-processed water becomes like this. Preferably it is 10 to 40 degreeC, More preferably, it is 15 to 37 degreeC.
　被処理水の生物化学的酸素要求量（Biochemical oxygen demand：ＢＯＤ）は、固定床型リアクタである嫌気性アンモニア酸化槽１の入口において、３００ｍｇ／Ｌ以下であることが好ましく、１５０ｍｇ／Ｌ以下であることがより好ましい。このようなＢＯＤであれば、通常の流量で通水している固定床型リアクタ内で有機物を十分に分解することができる。滞留時間を大きく延長しなくとも、処理槽内の下流側の有機物濃度が十分に低下するため、高活性で安定な嫌気性アンモニア酸化活性を得ることができる。 The biochemical oxygen demand (BOD) of the water to be treated is preferably 300 mg / L or less, preferably 150 mg / L or less at the inlet of the anaerobic ammonia oxidation tank 1 which is a fixed bed reactor. More preferably. With such a BOD, the organic matter can be sufficiently decomposed in a fixed bed reactor that allows water to flow at a normal flow rate. Even if the residence time is not greatly extended, the organic substance concentration on the downstream side in the treatment tank is sufficiently lowered, so that highly active and stable anaerobic ammonia oxidation activity can be obtained.
　嫌気性アンモニア酸化処理工程では、固定床型リアクタである嫌気性アンモニア酸化槽１が、曝気を行わず溶存酸素濃度を上昇させない無酸素条件下で被処理水を処理することが好ましい。被処理水に十分な溶存酸素が残存していると、曝気を行わなくとも、処理槽内の上流側で従属栄養性微生物が増殖し易くなる。そして、溶存酸素濃度が上昇しない条件であれば、下流側に流れる被処理水の有機物濃度が低下し易くなり、処理槽内の下流側では、嫌気性アンモニア酸化細菌が増殖し易くなる。よって、このような運転によると、有機物や溶存酸素を含む硝化処理後の処理水を、予め脱気処理することなく、低コストで効率的に脱窒することができる。 In the anaerobic ammonia oxidation treatment step, it is preferable that the anaerobic ammonia oxidation tank 1 which is a fixed bed reactor treats the water to be treated under anaerobic conditions in which aeration is not performed and the dissolved oxygen concentration is not increased. If sufficient dissolved oxygen remains in the water to be treated, heterotrophic microorganisms can easily grow on the upstream side in the treatment tank without aeration. If the dissolved oxygen concentration does not increase, the organic matter concentration of the water to be treated flowing downstream tends to decrease, and the anaerobic ammonia-oxidizing bacteria easily grow on the downstream side in the treatment tank. Therefore, according to such an operation, treated water after nitrification treatment containing organic matter and dissolved oxygen can be efficiently denitrified at low cost without being degassed in advance.
　嫌気性アンモニア酸化処理工程では、固定床型リアクタである嫌気性アンモニア酸化槽１で処理された処理水を、充填材２の下方に開口した流入口から固定床型リアクタ内に流入させて、微生物が固定化されている充填材２を物理洗浄することができる。処理水を洗浄用ポンプ９で固定床型リアクタ内に圧入することにより、充填材２が形成する充填層が微生物膜等で閉塞するのを防止することができる。 In the anaerobic ammonia oxidation treatment process, the treated water treated in the anaerobic ammonia oxidation tank 1 which is a fixed bed type reactor is caused to flow into the fixed bed type reactor from the inlet opening below the filler 2, and the microorganisms Can be physically washed. By pressing the treated water into the fixed bed reactor with the washing pump 9, it is possible to prevent the packed bed formed by the filler 2 from being clogged with a microbial membrane or the like.
　充填材２の物理洗浄は、被処理水を嫌気性アンモニア酸化処理する間に、所定の時間間隔で定期的に行ってもよいし、不定期に行ってもよい。物理洗浄のために必要な逆洗の展開率は、同一水温の下で処理水の線速度（Linear Velocity：ＬＶ）に依存し、担体ないしグラニュールの大きさや比重によっても異なる。そのため、展開率と線速度との関係を、使用する担体ないしグラニュール毎に、予め求めておくことが好ましい。 The physical cleaning of the filler 2 may be performed regularly at predetermined time intervals or irregularly during the anaerobic ammonia oxidation treatment of the water to be treated. The development rate of backwashing necessary for physical washing depends on the linear velocity of treated water (Linear Velocity: LV) at the same water temperature and varies depending on the size and specific gravity of the carrier or granule. Therefore, it is preferable to obtain in advance the relationship between the expansion rate and the linear velocity for each carrier or granule to be used.
　以上の窒素処理方法によると、嫌気性アンモニア酸化処理工程において、固定床型リアクタを用いるため、処理槽の上流側で有機物を分解し、処理槽の下流側で嫌気性アンモニア酸化させることができる。充填材が充填された固定床型リアクタでは、嫌気性アンモニア酸化細菌と従属栄養性微生物のそれぞれの生息域が分離されるため、被処理水に有機物や溶存酸素が含まれていても、高活性で安定な嫌気性アンモニア酸化活性を得ることができる。また、固定床型リアクタは、流動床型の処理槽と比較して、微生物汚泥の保持量を高くすることができるため、処理槽の容積当たりの脱窒速度を容易に向上させることができる。よって、窒素成分及び有機物を含む廃水を効率的に処理することができる。 According to the above nitrogen treatment method, since the fixed bed reactor is used in the anaerobic ammonia oxidation treatment step, organic substances can be decomposed on the upstream side of the treatment tank and anaerobic ammonia oxidation can be performed on the downstream side of the treatment tank. In a fixed bed reactor filled with fillers, the anaerobic ammonia-oxidizing bacteria and heterotrophic microorganisms have separate habitats, so even if the treated water contains organic matter or dissolved oxygen, it is highly active. And stable anaerobic ammonia oxidation activity can be obtained. In addition, since the fixed bed reactor can increase the amount of microbial sludge retained as compared with the fluidized bed processing tank, the denitrification rate per volume of the processing tank can be easily improved. Therefore, waste water containing nitrogen components and organic substances can be treated efficiently.
　また、以上の窒素処理方法によると、従属栄養性微生物による有機物の分解活性と、嫌気性アンモニア酸化細菌による高活性で安定な嫌気性アンモニア酸化活性とを、単槽式の処理槽で利用することができる。活性汚泥処理、脱気処理等の前処理を省略したり、前処理の処理時間を短縮したりしても、固定床型リアクタのみで、有機物の分解と、嫌気性アンモニア酸化反応とを行うことができる。よって、窒素成分及び有機物を含む廃水を低コストで効率的に処理することができる。 In addition, according to the above nitrogen treatment method, the decomposition activity of organic substances by heterotrophic microorganisms and the highly active and stable anaerobic ammonia oxidation activity by anaerobic ammonia oxidizing bacteria should be used in a single tank type treatment tank. Can do. Even if the pretreatment such as activated sludge treatment and deaeration treatment is omitted or the pretreatment time is shortened, the decomposition of organic substances and the anaerobic ammonia oxidation reaction should be performed only with the fixed bed reactor. Can do. Therefore, waste water containing nitrogen components and organic substances can be efficiently treated at low cost.
　図２は、窒素処理に用いられる廃水処理装置の他の例を示す模式図である。
　本実施形態に係る窒素処理方法は、図２に示されるような廃水処理装置２００を使用して実施することもできる。図２に示す廃水処理装置２００は、固定床型リアクタである嫌気性アンモニア酸化槽１と、微生物が固定化されている充填材２と、供給ポンプ３と、ｐＨ調整装置４と、溶液貯槽１０と、溶液供給ポンプ１１と、を備えている。供給ポンプ３、ｐＨ調整装置４、嫌気性アンモニア酸化槽１、及び、充填材２の構成は、廃水処理装置１００と略同様である。 FIG. 2 is a schematic diagram illustrating another example of a wastewater treatment apparatus used for nitrogen treatment.
The nitrogen treatment method according to the present embodiment can also be carried out using a wastewater treatment apparatus 200 as shown in FIG. A wastewater treatment apparatus 200 shown in FIG. 2 includes an anaerobic ammonia oxidation tank 1 that is a fixed bed reactor, a filler 2 on which microorganisms are immobilized, a supply pump 3, a pH adjuster 4, and a solution storage tank 10. And a solution supply pump 11. The configuration of the supply pump 3, the pH adjustment device 4, the anaerobic ammonia oxidation tank 1, and the filler 2 is substantially the same as that of the wastewater treatment device 100.
　廃水処理装置２００は、窒素成分を含む廃水（被処理水）を嫌気性アンモニア酸化法によって窒素処理する装置であり、アンモニア性窒素を含む被処理水に亜硝酸性窒素を含む溶液を混合して嫌気性アンモニア酸化処理する構成とされている。廃水処理装置２００は、嫌気性アンモニア酸化槽１が固定床型リアクタであるため、嫌気性アンモニア酸化細菌と従属栄養性微生物とを、処理槽内の異なる領域でそれぞれ繁殖させて、有機物の分解と嫌気性アンモニア酸化とを行うことができる。 The wastewater treatment apparatus 200 is an apparatus that treats wastewater containing nitrogen components (treated water) by anaerobic ammonia oxidation, and mixes a solution containing nitrite nitrogen with the treated water containing ammoniacal nitrogen. An anaerobic ammonia oxidation treatment is employed. In the wastewater treatment apparatus 200, since the anaerobic ammonia oxidation tank 1 is a fixed-bed reactor, anaerobic ammonia oxidation bacteria and heterotrophic microorganisms are propagated in different areas in the treatment tank to decompose organic matter. Anaerobic ammonia oxidation can be performed.
　嫌気性アンモニア酸化槽１は、微生物汚泥が固定化されている充填材２が充填された固定床型リアクタとされている。充填材２には、嫌気性アンモニア酸化細菌を含む微生物汚泥や従属栄養性微生物を含む微生物汚泥が固定化される。固定床を形成する充填材２は、筒型の処理槽内に保持され、充填材２の隙間に被処理水が通水し得るようになっている。 The anaerobic ammonia oxidation tank 1 is a fixed bed reactor filled with a filler 2 on which microbial sludge is immobilized. A microbial sludge containing anaerobic ammonia-oxidizing bacteria and a microbial sludge containing heterotrophic microorganisms are immobilized on the filler 2. The filler 2 forming the fixed bed is held in a cylindrical processing tank so that the water to be treated can be passed through the gap of the filler 2.
　嫌気性アンモニア酸化槽１は、図２において、処理槽の下部に流入口、処理槽の上部に流出口を有しており、被処理水を上向流として流す筒形の固定床型リアクタとされている。上向流を流す形式によると、微生物汚泥が底部に堆積したり、微生物汚泥が生じた窒素ガスや二酸化炭素が充填層中に蓄積したりするのが抑制される。流入口には、供給ポンプ３を備えた配管を介して、被処理水が供給される。また、溶液貯槽１０が、溶液供給ポンプ１１を備えた配管を介して接続される。溶液貯槽１０には、例えば、亜硝酸ナトリウム溶液、亜硝酸カリウム溶液等、亜硝酸性窒素を含む溶液が用意される。 In FIG. 2, the anaerobic ammonia oxidation tank 1 has an inlet at the lower part of the treatment tank and an outlet at the upper part of the treatment tank, and has a cylindrical fixed bed reactor for flowing the water to be treated as an upward flow. Has been. According to the form of flowing upward flow, microbial sludge is prevented from accumulating at the bottom, and accumulation of nitrogen gas or carbon dioxide produced by microbial sludge in the packed bed is suppressed. The water to be treated is supplied to the inflow port via a pipe provided with the supply pump 3. The solution storage tank 10 is connected via a pipe provided with a solution supply pump 11. In the solution storage tank 10, for example, a solution containing nitrite nitrogen such as a sodium nitrite solution and a potassium nitrite solution is prepared.
　嫌気性アンモニア酸化槽１には、アンモニア性窒素や有機物を含む被処理水が、供給ポンプ３によって供給される。また、亜硝酸性窒素を含む溶液を、溶液供給ポンプ１１によって溶液貯槽１０から供給することができる。アンモニア性窒素を含む被処理水と、亜硝酸性窒素を含む溶液とは、混合されて嫌気性アンモニア酸化槽１に導入され、有機物の分解や嫌気性アンモニア酸化が行われる。 The water to be treated containing ammoniacal nitrogen and organic substances is supplied to the anaerobic ammonia oxidation tank 1 by a supply pump 3. A solution containing nitrite nitrogen can be supplied from the solution storage tank 10 by the solution supply pump 11. The to-be-treated water containing ammonia nitrogen and the solution containing nitrite nitrogen are mixed and introduced into the anaerobic ammonia oxidation tank 1 to decompose organic matter and anaerobic ammonia oxidation.
　嫌気性アンモニア酸化槽１に供給される被処理水は、アンモニア性窒素の濃度と亜硝酸性窒素の濃度との比が１：１～１：１．５となるように、亜硝酸性窒素を含む溶液と混合されることが好ましい。このような濃度比に調整すると、嫌気性アンモニア酸化反応が効率的に進むため、高い窒素除去率を得ることができる。亜硝酸性窒素を含む溶液の供給量は、供給される被処理水のアンモニア性窒素の濃度を予め測定して制御することが好ましい。 The treated water supplied to the anaerobic ammonia oxidation tank 1 contains nitrite nitrogen so that the ratio of the ammonia nitrogen concentration to the nitrite nitrogen concentration is 1: 1 to 1: 1.5. It is preferable to mix with the solution containing. When adjusted to such a concentration ratio, the anaerobic ammonia oxidation reaction proceeds efficiently, so that a high nitrogen removal rate can be obtained. The supply amount of the solution containing nitrite nitrogen is preferably controlled by measuring in advance the concentration of ammonia nitrogen in the treated water to be supplied.
　嫌気性アンモニア酸化槽１には、嫌気性アンモニア酸化槽１で処理された処理水を処理槽内に返送するための循環ラインが設けられている。循環ラインを通じて処理水の一部を返送すると、嫌気性アンモニア酸化槽１におけるアンモニア性窒素濃度や有機物濃度を希釈することができる。また、溶存酸素濃度が低い領域においては、有機物を利用する従属栄養性脱窒細菌が、処理水中に残存している硝酸性窒素を分子状窒素に還元し得るため、窒素除去率を高めることができる。 The anaerobic ammonia oxidation tank 1 is provided with a circulation line for returning the treated water treated in the anaerobic ammonia oxidation tank 1 to the treatment tank. When a part of the treated water is returned through the circulation line, the ammonia nitrogen concentration and the organic matter concentration in the anaerobic ammonia oxidation tank 1 can be diluted. In addition, in regions where the dissolved oxygen concentration is low, heterotrophic denitrifying bacteria that use organic matter can reduce nitrate nitrogen remaining in the treated water to molecular nitrogen, thus increasing the nitrogen removal rate. it can.
　循環ラインによる処理水の返送は、被処理水のＢＯＤが、嫌気性アンモニア酸化槽１の入口において、３００ｍｇ／Ｌを超えるときに実施することが好ましい。このような条件で返送すると、滞留時間を大きく延長しなくとも、有機物を十分に分解することができる。このような返送を行う場合、循環ラインは、図２に示すように、被処理水の流入口に接続することが好ましい。 The return of the treated water through the circulation line is preferably performed when the BOD of the treated water exceeds 300 mg / L at the inlet of the anaerobic ammonia oxidation tank 1. When returned under such conditions, the organic matter can be sufficiently decomposed without greatly extending the residence time. When such return is performed, the circulation line is preferably connected to the inlet of the water to be treated as shown in FIG.
　また、循環ラインによる処理水の返送は、被処理水のアンモニア性窒素の濃度が、１５０ｍｇ／Ｌを超えるときに実施することが好ましい。このような条件で返送すると、嫌気性アンモニア酸化活性を安定させて、高い窒素除去率を得ることができる。このような返送を行う場合、循環ラインは、図２に示すように、被処理水の流入口に接続してもよいし、生息域が分離する中間部に接続してもよいが、中間部に接続することが好ましい。 Moreover, it is preferable to perform the return of the treated water by the circulation line when the concentration of ammoniacal nitrogen in the treated water exceeds 150 mg / L. When returned under such conditions, anaerobic ammonia oxidation activity can be stabilized and a high nitrogen removal rate can be obtained. When performing such return, the circulation line may be connected to the inlet of the water to be treated as shown in FIG. 2, or may be connected to the intermediate part where the habitat is separated. It is preferable to connect to.
　固定床型リアクタである嫌気性アンモニア酸化槽１において、上向流として通水される被処理水の線速度は、充填材２が担体である場合、２０ｍ／ｈ以下が好ましい。一方、充填材２がグラニュールである場合、２ｍ／ｈ以下が好ましい。このような線速度であると、上流側の充填材２と下流側の充填材２とが混合し難いため、嫌気性アンモニア酸化細菌と従属栄養性微生物のそれぞれの生息域を、明確に分離することができる。 In the anaerobic ammonia oxidation tank 1 which is a fixed bed type reactor, the linear velocity of the water to be treated that flows as an upward flow is preferably 20 m / h or less when the filler 2 is a carrier. On the other hand, when the filler 2 is granule, 2 m / h or less is preferable. At such a linear velocity, the upstream filler 2 and the downstream filler 2 are difficult to mix, so that the habitats of anaerobic ammonia-oxidizing bacteria and heterotrophic microorganisms are clearly separated. be able to.
　以上の窒素処理方法によると、嫌気性アンモニア酸化処理工程において、固定床型リアクタを用いるため、処理槽の上流側で有機物を分解し、処理槽の下流側で嫌気性アンモニア酸化を行うことができる。アンモニア性窒素を含む被処理水に、亜硝酸性窒素を含む溶液が混合されるため、被処理水に亜硝酸性窒素が含まれていない場合や、亜硝酸性窒素の濃度が適切でない場合にも、効率的に嫌気性アンモニア酸化処理することができる。例えば、亜硝酸型の硝化処理を省略したり、硝化処理における硝化率を任意に変更したりしても、高い窒素除去率が得られる。 According to the above nitrogen treatment method, since the fixed bed reactor is used in the anaerobic ammonia oxidation treatment step, organic substances can be decomposed upstream of the treatment tank and anaerobic ammonia oxidation can be performed downstream of the treatment tank. . Since the solution containing nitrite nitrogen is mixed with the water to be treated containing ammonia nitrogen, when the water to be treated does not contain nitrite nitrogen or the concentration of nitrite nitrogen is not appropriate Even an anaerobic ammonia oxidation treatment can be efficiently performed. For example, even if the nitrite type nitrification treatment is omitted or the nitrification rate in the nitrification treatment is arbitrarily changed, a high nitrogen removal rate can be obtained.
　以上、本発明の実施形態について説明したが、本発明は、前記の実施形態に限定されるものではなく、本発明の趣旨を逸脱しない範囲において種々の変更が可能である。例えば、本発明の趣旨を逸脱しない範囲において、実施形態の構成の一部を他の構成に置き換えたり、実施形態の構成の一部を他の形態に追加したり、実施形態の構成の一部を省略したりすることも可能である。 As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, without departing from the spirit of the present invention, a part of the configuration of the embodiment is replaced with another configuration, a part of the configuration of the embodiment is added to another form, or a part of the configuration of the embodiment Can be omitted.
　例えば、前記の廃水処理装置１００において、アンモニア酸化槽５は、被処理水の全量を亜硝酸型硝化するワンパス式とされているが、バイパス式とされてもよい。すなわち、被処理水の一部をアンモニア酸化槽５に導入してアンモニア性窒素の全量を亜硝酸性窒素にまで酸化し、残部を迂回させて亜硝酸型硝化せず嫌気性アンモニア酸化槽１に合流させてもよい。 For example, in the wastewater treatment apparatus 100 described above, the ammonia oxidation tank 5 is a one-pass type that nitrifies the entire amount of water to be treated, but may be a bypass type. That is, a part of the water to be treated is introduced into the ammonia oxidation tank 5 to oxidize the entire amount of ammonia nitrogen to nitrite nitrogen, and the remainder is bypassed to the anaerobic ammonia oxidation tank 1 without nitrite type nitrification. You may join.
　また、前記の廃水処理装置１００を上向流で運転する方式とし、廃水処理装置２００を下向流で運転する方式としてもよい。廃水処理装置１００に、嫌気性アンモニア酸化槽１で処理された処理水を嫌気性アンモニア酸化槽１に返送するための循環ラインを設けてもよいし、廃水処理装置２００に、循環ラインを設けなくてもよい。ｐＨ調整装置４は、嫌気性アンモニア酸化槽１の供給側、及び、循環ラインのうち、いずれに設けてもよい。 Alternatively, the wastewater treatment apparatus 100 may be operated in an upward flow, and the wastewater treatment apparatus 200 may be operated in a downward flow. The wastewater treatment apparatus 100 may be provided with a circulation line for returning the treated water treated in the anaerobic ammonia oxidation tank 1 to the anaerobic ammonia oxidation tank 1, or the wastewater treatment apparatus 200 is not provided with a circulation line. May be. The pH adjusting device 4 may be provided on either the supply side of the anaerobic ammonia oxidation tank 1 or the circulation line.
　また、前記の廃水処理装置１００，２００には、嫌気性アンモニア酸化槽１で処理された処理水をアンモニア酸化槽５に返送するための循環ラインを設けてもよい。循環ラインを通じて処理水の一部を返送すると、アンモニア酸化槽１における亜硝酸性窒素濃度を希釈することができる。 Further, the waste water treatment apparatus 100, 200 may be provided with a circulation line for returning the treated water treated in the anaerobic ammonia oxidation tank 1 to the ammonia oxidation tank 5. When a part of the treated water is returned through the circulation line, the nitrite nitrogen concentration in the ammonia oxidation tank 1 can be diluted.
　また、前記の固定床型リアクタは、有機物や溶存酸素の濃度分極を生じる限り、被処理水を攪拌する攪拌装置を備えることができる。攪拌装置の羽根形状は、例えば、パドル翼式、アンカー翼式、リボン翼式、ゲート翼式、プロペラ翼式、糸巻形翼式等とすることができる。攪拌装置の回転速度（回転数）は、２００ｍｉｎ－１以下が好ましく、１００ｍｉｎ－１以下がより好ましい。このような緩速であると、濃度分極を維持して生息域を分離することができる。 In addition, the fixed bed reactor can be equipped with a stirring device that stirs the water to be treated as long as concentration polarization of organic matter or dissolved oxygen occurs. The blade shape of the stirrer can be, for example, a paddle wing type, an anchor wing type, a ribbon wing type, a gate wing type, a propeller wing type, a pincushion wing type, or the like. Rotation speed (rpm) of the stirrer is preferably 200 min -1 or less, 100 min -1 or less is more preferable. With such a slow speed, the habitat can be separated while maintaining the concentration polarization.
　また、前記の固定床型リアクタは、形状が特に制限されるものではない。例えば、円筒型、角筒型、多角筒型、多重筒型等の適宜の形状とすることができる。固定床型リアクタの有効幅（処理槽内の短辺の長さ、又は、直径）は、担体ないしグラニュールの大きさ（長辺の長さ、又は、直径）の３０倍以上の長さであることが好ましく、５０倍以上の長さであることがより好ましい。このような寸法であると、固定床型リアクタ内で担体ないしグラニュールが偏り難いため、充填層が閉塞したり、空乏な非充填部が充填層を貫通したりするのを抑制することができる。 Further, the shape of the fixed bed reactor is not particularly limited. For example, an appropriate shape such as a cylindrical shape, a rectangular tube shape, a polygonal tube shape, or a multiple tube shape can be used. The effective width (length or diameter of the short side in the treatment tank) of the fixed bed reactor is 30 times or more the size of the carrier or granule (length or length of the long side). It is preferable that the length is 50 times or more. With such dimensions, the support or granule is less likely to be biased in the fixed bed reactor, so that the packed bed can be prevented from being blocked or the depleted unfilled portion from penetrating the packed bed. .
　固定床型リアクタに充填する充填材２同士の隙間は、非ペレット状の充填材２を固定床型リアクタに対して固定する場合、０．７ｍｍ以上であることが好ましく、３ｍｍ以上であることがより好ましい。このような寸法であると、充填材２同士が接触し難くなるため、微生物汚泥の剥離、担体の割れ、破れ等を抑制することができる。充填材２が損傷し難くなる結果、破片による充填層の閉塞も抑制される。 The gap between the fillers 2 filled in the fixed bed reactor is preferably 0.7 mm or more and preferably 3 mm or more when the non-pellet-like filler 2 is fixed to the fixed bed reactor. More preferred. Since it becomes difficult for the fillers 2 to contact each other with such dimensions, microbial sludge peeling, carrier cracking, tearing, and the like can be suppressed. As a result of the filler 2 becoming difficult to be damaged, blockage of the filler layer due to debris is also suppressed.
　また、前記の廃水処理装置１００，２００において、嫌気性アンモニア酸化槽１やアンモニア酸化槽５の前段側には、廃水の水質や水量を調整する調整槽や、廃水に含まれている有機物を生物学的に分解する生物反応槽や、廃水に含まれている硝酸性窒素を予め脱窒する前脱窒槽等が設けられてもよい。また、後段側には、嫌気性アンモニア酸化反応で生成した硝酸性窒素を脱窒する後脱窒槽等が設けられてもよい。廃水処理装置２００の前段側には、硝酸性窒素を含む溶液を混合する混合槽が設けられてもよい。 Further, in the waste water treatment apparatuses 100 and 200, the anterior stage of the anaerobic ammonia oxidation tank 1 and the ammonia oxidation tank 5 is an adjustment tank that adjusts the quality and amount of waste water, and organic substances contained in the waste water. A biological reaction tank that decomposes chemically, a pre-denitrification tank that denitrifies nitrate nitrogen contained in wastewater in advance, and the like may be provided. Further, a post-denitrification tank or the like for denitrifying nitrate nitrogen generated by the anaerobic ammonia oxidation reaction may be provided on the rear side. A mixing tank for mixing a solution containing nitrate nitrogen may be provided on the front side of the wastewater treatment apparatus 200.
　以下、本発明の実施例を用いて本発明をより詳細に説明するが、本発明の技術的範囲はこれに限定されるものではない。 Hereinafter, the present invention will be described in more detail using examples of the present invention, but the technical scope of the present invention is not limited thereto.
［実施例１］
　嫌気性アンモニア酸化細菌と従属栄養性微生物を含む活性汚泥との混成である微生物汚泥が固定化された包括固定化担体を用意した。この包括固定化担体を、容積０．５Ｌのリアクタに容積０．３Ｌとなるように充填し、この固定床型リアクタを２０℃の恒温槽内に設置した。そして、アンモニア性窒素の濃度が４０ｍｇ－Ｎ／Ｌ、ＢＯＤが５０ｍｇ／Ｌである原水を、アンモニア性窒素の濃度と亜硝酸性窒素の濃度との比が１：１～１：１．５となるように硝化処理した後に、水理学的滞留時間が１時間となるようにリアクタの下部から通水した。被処理水の脱気処理や、処理水の返送は行わず、被処理水のｐＨは、通水前にｐＨ７．６に調整した。 [Example 1]
A entrapping immobilization support was prepared in which microbial sludge, which is a hybrid of anaerobic ammonia oxidizing bacteria and activated sludge containing heterotrophic microorganisms, was immobilized. The entrapping immobilization support was filled in a reactor having a volume of 0.5 L so as to have a volume of 0.3 L, and the fixed bed reactor was placed in a constant temperature bath at 20 ° C. Then, the raw water having an ammonia nitrogen concentration of 40 mg-N / L and a BOD of 50 mg / L is used. The ratio of the ammonia nitrogen concentration to the nitrite nitrogen concentration is 1: 1 to 1: 1.5. After the nitrification treatment, water was passed from the lower part of the reactor so that the hydraulic residence time was 1 hour. The degassing treatment of the water to be treated and the return of the treated water were not performed, and the pH of the water to be treated was adjusted to pH 7.6 before passing water.
　窒素処理が定常に達したとき、アンモニア性窒素の濃度は０．２ｍｇ／Ｌ、亜硝酸性窒素の濃度は０．９ｍｇ／Ｌ、硝酸性窒素の濃度は６ｍｇ／Ｌであった。リアクタに充填した担体は、硝化処理されている被処理水が流入する下部側では、茶色を呈しており、従属栄養性微生物が繁殖している可能性が認められた。一方、リアクタの上部側ほど、赤色が強くなり、嫌気性アンモニア酸化細菌の繁殖が確認された。 When the nitrogen treatment reached a steady state, the concentration of ammonia nitrogen was 0.2 mg / L, the concentration of nitrite nitrogen was 0.9 mg / L, and the concentration of nitrate nitrogen was 6 mg / L. The carrier filled in the reactor has a brown color on the lower side where the water to be treated that has undergone nitrification flows, and it was confirmed that heterotrophic microorganisms had propagated. On the other hand, the red color of the upper part of the reactor became stronger and the growth of anaerobic ammonia oxidizing bacteria was confirmed.
［比較例１］
　嫌気性アンモニア酸化細菌と従属栄養性微生物を含む活性汚泥との混成である微生物汚泥が固定化された包括固定化担体を用意した。この包括固定化担体を、容積０．５Ｌのリアクタに容積０．１Ｌとなるように投入し、この流動床型リアクタを２０℃の恒温槽内に設置した。そして、アンモニア性窒素の濃度が４０ｍｇ－Ｎ／Ｌ、ＢＯＤが５０ｍｇ／Ｌである原水を、アンモニア性窒素の濃度と亜硝酸性窒素の濃度との比が１：１～１：１．５となるように硝化処理した後に、水理学的滞留時間が３時間となるようにリアクタの下部から通水した。被処理水の脱気処理や、処理水の返送は行わず、リアクタ内の被処理水は、担体が浮遊する程度に攪拌し、被処理水のｐＨは、通水前にｐＨ７．６に調整した。 [Comparative Example 1]
A entrapping immobilization support was prepared in which microbial sludge, which is a hybrid of anaerobic ammonia oxidizing bacteria and activated sludge containing heterotrophic microorganisms, was immobilized. This entrapping immobilization support was put into a reactor having a volume of 0.5 L so as to have a volume of 0.1 L, and this fluidized bed reactor was placed in a constant temperature bath at 20 ° C. Then, the raw water having an ammonia nitrogen concentration of 40 mg-N / L and a BOD of 50 mg / L is used. The ratio of the ammonia nitrogen concentration to the nitrite nitrogen concentration is 1: 1 to 1: 1.5. After the nitrification treatment, water was passed from the lower part of the reactor so that the hydraulic residence time was 3 hours. The treated water in the reactor is stirred to such an extent that the carrier floats, and the pH of the treated water is adjusted to pH 7.6 before passing water. did.
　窒素処理が定常に達したとき、アンモニア性窒素の濃度は１５ｍｇ／Ｌ、亜硝酸性窒素の濃度は１５ｍｇ／Ｌ、硝酸性窒素の濃度は０．６ｍｇ／Ｌであった。リアクタ内に投入した担体は、全体的に茶色を呈しており、従属栄養性微生物が繁殖している可能性が認められたが、嫌気性アンモニア酸化細菌の繁殖を示す赤色の担体は、殆ど確認されなかった。 When the nitrogen treatment reached a steady state, the concentration of ammonia nitrogen was 15 mg / L, the concentration of nitrite nitrogen was 15 mg / L, and the concentration of nitrate nitrogen was 0.6 mg / L. The carrier introduced into the reactor is generally brown, and there is a possibility that heterotrophic microorganisms have propagated. However, the red carrier indicating the growth of anaerobic ammonia-oxidizing bacteria is almost confirmed. Was not.
　実施例１と比較例１の結果が示すように、濃度分極を生じる固定床型リアクタと、完全混合となる流動床型リアクタとでは、窒素処理の効率が異なる。比較例１の流動床型リアクタでは、嫌気性アンモニア酸化細菌が十分に繁殖せず、嫌気性アンモニア酸化活性が殆ど認められなかったのに対し、実施例１の固定床型リアクタでは、嫌気性アンモニア酸化細菌が増殖して、高い窒素除去率が得られた。したがって、固定床型リアクタで嫌気性アンモニア酸化処理を行うと、被処理水に有機物が含まれていても、有機物を活性汚泥処理等によって予め除去することなく、効率的に脱窒することができるといえる。 As shown in the results of Example 1 and Comparative Example 1, the efficiency of nitrogen treatment is different between a fixed bed reactor that causes concentration polarization and a fluidized bed reactor that is completely mixed. In the fluidized bed reactor of Comparative Example 1, the anaerobic ammonia oxidizing bacteria did not propagate sufficiently, and almost no anaerobic ammonia oxidizing activity was observed, whereas in the fixed bed reactor of Example 1, anaerobic ammonia was used. Oxidizing bacteria grew and a high nitrogen removal rate was obtained. Therefore, when anaerobic ammonia oxidation treatment is performed in a fixed bed reactor, even if organic matter is contained in the water to be treated, it can be efficiently denitrified without removing the organic matter in advance by activated sludge treatment or the like. It can be said.
１　　　嫌気性アンモニア酸化槽（固定床型リアクタ）
２　　　充填材
３　　　供給ポンプ
４　　　ｐＨ調整装置
５　　　アンモニア酸化槽
６　　　微生物汚泥
７　　　散気装置
８　　　処理水槽
９　　　洗浄用ポンプ
１０　　溶液貯槽
１１　　溶液供給ポンプ
１００　廃水処理装置
２００　廃水処理装置 1 Anaerobic ammonia oxidation tank (fixed bed reactor)
2 Filler 3 Supply pump 4 pH adjustment device 5 Ammonia oxidation tank 6 Microbial sludge 7 Aeration device 8 Treatment water tank 9 Cleaning pump 10 Solution storage tank 11 Solution supply pump 100 Waste water treatment device 200 Waste water treatment device

Claims (9)

  1. 　廃水に含まれる窒素成分を脱窒する窒素処理方法であって、
    　被処理水に含まれるアンモニア性窒素と亜硝酸性窒素とを微生物汚泥によって分子状窒素に変換する嫌気性アンモニア酸化処理工程を含み、
    　前記嫌気性アンモニア酸化処理工程において、前記微生物汚泥が固定化されている充填材が保持された固定床型リアクタを用いて前記被処理水を処理する窒素処理方法。     A nitrogen treatment method for denitrifying nitrogen components contained in waste water,
    Including anaerobic ammonia oxidation treatment step of converting ammonia nitrogen and nitrite nitrogen contained in the water to be treated into molecular nitrogen by microbial sludge,
    In the anaerobic ammonia oxidation treatment step, a nitrogen treatment method of treating the water to be treated using a fixed bed reactor in which a filler to which the microbial sludge is immobilized is held.
  2. 　前記微生物汚泥が、アンモニア性窒素を水素供与体としてアンモニア性窒素と亜硝酸性窒素とを共脱窒する嫌気性アンモニア酸化細菌と、前記被処理水に含まれる有機物を分解する従属栄養性微生物と、を含む請求項１に記載の窒素処理方法。 The microbial sludge is an anaerobic ammonia oxidizing bacterium that co-denitrifies ammoniacal nitrogen and nitrite nitrogen using ammoniacal nitrogen as a hydrogen donor, and heterotrophic microorganisms that decompose organic substances contained in the water to be treated. The nitrogen treatment method according to claim 1, comprising:
  3. 　前記微生物汚泥が、担体に包括固定化されている状態、担体に付着固定化されている状態、又は、自己造粒によるグラニュールを形成している状態である請求項１に記載の窒素処理方法。 The nitrogen treatment method according to claim 1, wherein the microbial sludge is in a state of being comprehensively immobilized on a carrier, in a state of being adhered and immobilized on a carrier, or in a state of forming granules by self-granulation. .
  4. 　前記固定床型リアクタが、無酸素条件下で前記被処理水を処理する請求項１に記載の窒素処理方法。 The nitrogen treatment method according to claim 1, wherein the fixed bed reactor treats the water to be treated under oxygen-free conditions.
  5. 　前記嫌気性アンモニア酸化処理工程の前に、被処理水に含まれるアンモニア性窒素を微生物汚泥によって酸化して亜硝酸性窒素を生成する硝化処理工程を含む請求項１に記載の窒素処理方法。 The nitrogen treatment method according to claim 1, further comprising a nitrification treatment step in which ammonia nitrogen contained in the water to be treated is oxidized by microbial sludge to generate nitrite nitrogen before the anaerobic ammonia oxidation treatment step.
  6. 　前記嫌気性アンモニア酸化処理工程の前に、アンモニア性窒素を含む被処理水と、亜硝酸性窒素を含む溶液とを混合して前記固定床型リアクタに導入し、混合された前記被処理水を処理する請求項１に記載の窒素処理方法。 Prior to the anaerobic ammonia oxidation treatment step, water to be treated containing ammonia nitrogen and a solution containing nitrite nitrogen are mixed and introduced into the fixed bed reactor, and the water to be treated is mixed. The nitrogen treatment method according to claim 1 to be treated.
  7. 　前記嫌気性アンモニア酸化処理工程において、前記固定床型リアクタで処理された処理水を、前記充填材の下方に開口した流入口から前記固定床型リアクタ内に流入させて、前記充填材を物理洗浄する請求項１に記載の窒素処理方法。 In the anaerobic ammonia oxidation treatment step, the treated water treated in the fixed bed type reactor is caused to flow into the fixed bed type reactor from an inlet opening below the filler to physically wash the filler. The nitrogen treatment method according to claim 1.
  8. 　前記被処理水の全窒素の濃度が１０ｍｇ／Ｌ以上１５０ｍｇ／Ｌ以下である請求項１に記載の窒素処理方法。 The nitrogen treatment method according to claim 1, wherein the concentration of total nitrogen of the water to be treated is 10 mg / L or more and 150 mg / L or less.
  9. 　前記被処理水の生物化学的酸素要求量が３００ｍｇ／Ｌ以下である請求項１に記載の窒素処理方法。 The nitrogen treatment method according to claim 1, wherein the biochemical oxygen demand of the water to be treated is 300 mg / L or less.
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