JP5814768B2 - Nitrogen-containing organic wastewater treatment system and treatment method - Google Patents

Description

  The present invention relates to a treatment system and treatment method for nitrogen-containing organic wastewater, and more particularly to a treatment system and treatment method suitable for nitrogen-containing organic wastewater having a relatively low ammonia concentration.

  Conventionally, biological nitrification denitrification methods using heterotrophic microorganisms such as a circulation denitrification method have been employed to treat nitrogen-containing organic wastewater. Such a nitrification denitrification method includes a nitrification step in which ammonia nitrogen in wastewater is oxidized to nitrite nitrogen by ammonia-oxidizing bacteria, and nitrite nitrogen is oxidized to nitrate nitrogen by nitrite-oxidizing bacteria; This is a method of decomposing ammonia nitrogen in waste water into nitrogen molecules through a denitrification step of decomposing nitrogen and nitrate nitrogen into nitrogen molecules by heterotrophic denitrifying bacteria.

  However, in such a conventional biological nitrification denitrification method, a large amount of oxygen is required in the nitrification process, and the power cost required for a blower fan for aeration increases, and a large amount of organic carbon source in the denitrification process. Running costs increase, such as the problem of increased chemical costs for the addition of methanol, and the problem of increased sludge generation due to the use of heterotrophic microorganisms, resulting in increased waste sludge treatment costs. There was a problem.

  Therefore, Patent Document 1 discloses an anaerobic treatment process for removing BOD by an anaerobic methane fermentation method with respect to BOD and nitrogen-containing wastewater, a nitrite-type nitrification process in which a part of ammonia nitrogen is nitrite nitrogen, A biological treatment method for BOD and nitrogen-containing wastewater that is treated in the order of a denitrification process in which ammonia nitrogen is used as an electron donor and nitrite nitrogen is used as an electron acceptor in contact with an autotrophic denitrification microorganism. A biological treatment of BOD and nitrogen-containing wastewater using a (bi) carbonate-containing alkaline solution obtained by contacting the biogas generated in the anaerobic treatment step with an alkaline solution for pH adjustment in the nitrite type nitrification step A method has been proposed.

  In the present specification, the present invention will be described using the term “waste water”, but the term “waste water” used in known literature is synonymous.

  According to this method, it is not necessary to add an organic substance because ANAMMOX bacteria, which are autotrophic denitrifying microorganisms, are used for denitrification, and sludge is also generated because ANAMMOX bacteria are autotrophic microorganisms with a low yield. The amount of generated water is remarkably reduced and the amount of excess sludge generated can be suppressed.

  The biogas generated in the anaerobic treatment step was brought into contact with an alkaline solution for pH adjustment to stably perform nitrite-type nitrification by stopping the oxidation of ammonia nitrogen in raw water to nitrite nitrogen ( The chemical cost can be reduced by using a heavy carbonate-containing alkaline solution instead of a commercially available drug.

  In addition, Patent Document 2 discloses biological nitrogen containing an anaerobic ammonia oxidation treatment that converts an ammonia nitrogen and a nitrite nitrogen into nitrogen molecules under anaerobic conditions for a target treatment liquid containing an ammonia component and a BOD component. A removal system has been proposed.

  The biological nitrogen removal system includes a BOD separation device into which a target treatment liquid containing nitrogen flows and a treatment containing mainly nitrite nitrogen into which an ammonia-containing liquid separated by the BOD separation device flows. An anaerobic ammonia oxidation tank to obtain a liquid, an anaerobic ammonia oxidation tank into which a nitrite-containing nitrogen-containing treatment liquid flows, an anaerobic denitrification tank into which a treatment liquid discharged from the anaerobic ammonia oxidation tank flows, and the anaerobic And a re-aeration tank into which the treatment liquid from the oxidative denitrification tank flows, and a line for guiding the BOD-containing liquid separated by the BOD separation device to the anaerobic denitrification tank. In addition, a pretreatment device such as a screen and a sedimentation tank for removing impurities contained in the target treatment liquid is provided on the upstream side of the BOD separation device.

Japanese Patent No. 4496735 Japanese Patent No. 4632356

  However, there has been no active research on anaerobic ammonia oxidation treatment for wastewater with low ammonia concentration, including suspended organic substances, so efficient anaerobic ammonia oxidation treatment for such wastewater. A realistic processing system and processing method capable of performing the above has not been developed yet.

  For example, when the method described in Patent Document 1 is adopted for such waste water, even if the soluble BOD is reduced by the anaerobic digestion treatment performed in the pretreatment of nitritation, the suspended BOD is sufficiently removed. Therefore, the power cost for the large amount of aeration required to simultaneously decompose the suspended BOD in the nitritation step increases.

  Moreover, when the method described in Patent Document 2 is adopted for such wastewater, suspended organic substances are removed, but nitrous acid is stably generated in an aerobic ammonia oxidation tank because the ammonia concentration is low. There was a problem that ammonia and nitric acid leaked without sufficient treatment in the anaerobic ammonia oxidation tank in the next step.

  In view of the above-mentioned problems, the object of the present invention is more efficient than the prior art and is anaerobically efficient using autotrophic microorganisms even for wastewater with a low ammonia concentration containing suspended organic substances. The object is to provide a treatment system and treatment method for nitrogen-containing organic wastewater capable of ammonia oxidation treatment.

  In order to achieve the above object, a first characteristic configuration of a treatment system for nitrogen-containing organic wastewater according to the present invention contains suspended organic matter and ammonia as described in claim 1 of the claims. Nitrite treatment to oxidize ammonia to nitrous acid by autotrophic microorganisms under aerobic conditions, and ammonia nitrogen by autotrophic microorganisms as an electron donor and nitrous acid under anaerobic conditions A nitrogen-containing organic wastewater treatment system having an autotrophic denitrification device for performing denitrification treatment by anaerobic ammonia oxidation treatment using nitrogen as an electron acceptor, which is disposed upstream of the autotrophic denitrification device. And a sludge anaerobic digester for anaerobically digesting the suspended organic matter separated by the suspended organic matter separator, and a soil anaerobic digester for separating the suspended organic matter from the water to be treated. Certain digestive juices anaerobic digester at a point which is characterized by comprising a first transfer path to be supplied to the autotrophic denitrification device.

  Until now, it has not been possible to achieve an efficient and anaerobic ammonia oxidation treatment for wastewater with a low ammonia concentration. In an atmosphere where the ammonia concentration is low, it is not possible to stabilize the regulation of the nitritation to proceed by suppressing nitrification of ammonia, and in the partial nitritation that nitrites about half of the ammonia, the remaining ammonia The reason is that the amount adjustment cannot be stabilized.

  According to the above configuration, as a result of the anaerobic digestion of the suspended organic material separated by the suspended organic matter separation device by the sludge anaerobic digester, a digested liquid enriched with ammonia nitrogen is obtained. By supplying such digestive fluid to the autotrophic denitrifier, the autotrophic denitrifier increases the free ammonia concentration (FA), reduces the activity of nitrifying bacteria, and nitrites. As a result, nitritation by bacteria preferentially proceeds, and anaerobic ammonia oxidation treatment is efficiently performed. As a result, it is not necessary to suppress nitrifying bacteria by controlling temperature and pH, and power costs and chemical costs can be saved. Anthonisen et al. Reported that nitrates were selectively inhibited when the free ammonia concentration (FA) was 0.1-10 ppm.

  In addition to the first characteristic configuration described above, the autotrophic denitrification apparatus performs the nitritation treatment on the water to be treated, as described in claim 2. A nitritation apparatus; and an anaerobic ammonia oxidation apparatus that performs the anaerobic ammonia oxidation treatment on the treated water that has been subjected to the nitritation treatment, wherein the first transfer path includes the sludge anaerobic digestion. It is a path for supplying the digestive liquid of the apparatus to the nitritation apparatus, and has a second transfer path for supplying the digested liquid of the sludge anaerobic digester to the anaerobic ammonia oxidizing apparatus. It is in.

  When the autotrophic denitrification apparatus is configured with a two-tank system of a nitrification apparatus and an anaerobic ammonia oxidation apparatus, the digestive liquid is supplied to the nitritation apparatus by the first transfer path, and is supplied by the second transfer path. Supplied to anaerobic ammonia oxidizer. With this configuration, the ammonia concentration and the nitrous acid concentration in the anaerobic ammonia oxidation apparatus can be adjusted to an appropriate ratio, and the anaerobic ammonia oxidation can be advanced efficiently.

The anaerobic ammonia oxidation reaction is performed by an autotrophic bacterium using 1 equivalent of ammonia nitrogen as an electron donor and about 1.3 equivalents of nitrite nitrogen as an electron acceptor, as represented by the following formula. Denitrification reaction.
NH ₄ ⁺ + 1.32NO ₂ ⁻ + 0.066HCO ₃ ⁻ + 0.13H ⁺ →
1.02N ₂ + 0.26NO ₃ ⁻ + 0.066CH ₂ O _0.5 N _0.15 + 2.03H ₂ O

  If the molar ratio of nitrite nitrogen and ammonia nitrogen of the nitrification solution partially nitritized in the nitritation unit is the above formula, the anaerobic ammonia oxidation treatment will proceed efficiently. If the ratio is significantly different, the anaerobic ammonia oxidation treatment is delayed. Even in such a case, the molar ratio of nitrite nitrogen to ammonia nitrogen is set to an appropriate value, for example, 1: 1.3 to 1.4 by the digestion liquid having a high ammonia concentration supplied through the second transfer path. Therefore, anaerobic ammonia oxidation can proceed efficiently.

  As described in claim 3, the third characteristic configuration includes, in addition to the first characteristic configuration described above, nitrite nitrogen and nitrate nitrogen in the first transfer path by heterotrophic denitrifying microorganisms. A heterotrophic denitrification apparatus for performing denitrification treatment for reducing nitrogen to nitrogen molecules, and a third transfer path for supplying a treatment liquid of the autotrophic denitrification apparatus to the heterotrophic denitrification apparatus This is a feature.

  According to the above-described configuration, a part of the treatment liquid of the autotrophic denitrification apparatus is returned to the heterotrophic denitrification apparatus by the third transfer path, so that the main liquid contained in the digestion liquid of the sludge anaerobic digestion apparatus. By using a denitrifying treatment with heterotrophic denitrifying microorganisms that use soluble organic matter as an electron donor and nitrate nitrogen contained in the treatment liquid of the autotrophic denitrifying device as an electron acceptor, The amount of nitric acid discharged out of the system from the denitrification device can be reduced.

  In the fourth feature configuration, as described in claim 4, in addition to the second feature configuration described above, nitrite nitrogen and nitrate nitrogen are added to the first transfer path by heterotrophic denitrifying microorganisms. A heterotrophic denitrification device for performing denitrification treatment for reducing nitrogen to molecular molecules, and a third transfer path for supplying the treatment liquid of the anaerobic ammonia oxidation device to the heterotrophic denitrification device It is in the point characterized by.

  According to the above-described configuration, a part of the treatment liquid of the anaerobic ammonia oxidation apparatus is returned to the heterotrophic denitrification apparatus by the third transfer path, so that it is mainly contained in the digestion liquid of the sludge anaerobic digestion apparatus. Anaerobic ammonia oxidizer by denitrifying treatment with heterotrophic denitrifying microorganisms using soluble organic substance as electron donor and nitrate nitrogen contained in treatment liquid of anaerobic ammonia oxidizer as electron acceptor The amount of nitric acid discharged from the system can be reduced.

In the fifth feature configuration, in addition to any of the first to fourth feature configurations described above, the water to be treated is 1) NH ₃ -N (ammonia nitrogen concentration) ) <100 ppm, 2) BOD / NH ₃ —N> 3.0, and the suspension of the suspending organic matter separation device is 3) 0.5 <BOD / NH ₃ —N <2.0 It is in the point characterized by.

In the autotrophic denitrification device, the dissolved oxygen concentration is controlled to an appropriate range by adjusting the amount of aeration. However, if the ammonia nitrogen concentration is less than 100 ppm, the dissolved oxygen concentration increases with a slight change in the amount of aeration air. It will fluctuate. Even in such a case, by adjusting BOD / NH ₃ —N to a value larger than 0.5, large fluctuations in the dissolved oxygen concentration due to consumption of oxygen by BOD can be suppressed. Incidentally, increasing the aeration amount when BOD / _NH 3 -N exceeds 2.0, undesirable from the viewpoint of energy saving.

  The first characteristic configuration of the method for treating nitrogen-containing organic wastewater according to the present invention is independent of the water to be treated containing suspended organic matter and ammonia under the aerobic condition as described in claim 6. Nitrite treatment that oxidizes ammonia to nitrous acid by nutritional microorganisms, anaerobic ammonia oxidation treatment by anaerobic microorganisms using ammonia nitrogen as an electron donor and nitrite nitrogen as an electron acceptor under anaerobic conditions A nitrogen-containing organic wastewater treatment method for performing an autotrophic denitrification treatment by a suspending organic matter separation treatment for separating suspended organic matter from the water to be treated before the autotrophic denitrification treatment. Performing the anaerobic digestion of the suspending organic matter separated by the suspending organic matter separation treatment and supplying the digested solution to the autotrophic denitrification treatment.

  As described in the claim 7, the second characteristic configuration is the above-mentioned first characteristic configuration, the nitritation treatment and the anaerobic ammonia oxidation treatment are independent processing steps, The digestive juice is distributedly supplied to the nitritation treatment and the anaerobic ammonia oxidation treatment.

  As described in claim 8, the third characteristic configuration includes nitrite nitrogen and nitrate nitrogen by the heterotrophic denitrifying microorganisms in addition to the first characteristic configuration described above. The heterotrophic denitrification treatment is performed to reduce the amount of nitrogen to the nitrogen molecules, the treatment liquid subjected to the heterotrophic denitrification treatment is supplied to the autotrophic denitrification treatment, and the treatment liquid by the autotrophic denitrification treatment is It is characterized by being supplied to heterotrophic denitrification treatment.

  In the fourth feature configuration, in addition to the second feature configuration described above, nitrite nitrogen and nitrate nitrogen are added to the digested liquid by heterotrophic denitrification microorganisms. The heterotrophic denitrification treatment is performed to reduce the oxygen to nitrogen molecules, the treatment liquid subjected to the heterotrophic denitrification treatment is supplied to the nitritation treatment, and the treatment liquid by the anaerobic ammonia oxidation treatment is supplied to the heterotrophic nutrient treatment. This is characterized in that it is supplied to the denitrification treatment.

  As described above, according to the present invention, anaerobic ammonia oxidation is efficiently performed using autotrophic microorganisms even in wastewater having a low ammonia concentration that is more efficient than the prior art and contains suspended organic substances. It has become possible to provide a treatment system and treatment method for nitrogen-containing organic wastewater that can be treated.

Explanatory drawing of the 1st aspect of the processing system by this invention Explanatory drawing of the 2nd aspect of the processing system by this invention Explanatory drawing of the 3rd aspect of the processing system by this invention. Explanatory drawing of the 4th aspect of the processing system by this invention. Explanatory drawing of the processing system by this invention

Hereinafter, embodiments of a treatment system and treatment method for nitrogen-containing organic wastewater according to the present invention will be described.
FIG. 1 shows a nitrogen-containing organic wastewater treatment system according to the first embodiment. The said processing system is a system which purifies the to-be-processed water containing a suspending organic substance and ammonia, the suspending organic substance separation apparatus 10 which isolate | separates the suspending organic substance contained in a to-be-processed water, and a suspending organic substance The sludge anaerobic digester 40 for anaerobically digesting suspended organic matter separated by the separator 10 and the denitrification treatment of the separated organic matter separator 10 by the nitritation treatment and the anaerobic ammonia oxidation treatment are performed independently. There is provided a first transfer path R <b> 1 that supplies the digestive liquid of the nutrient denitrification device 30 and the sludge anaerobic digestion device 40 to the autotrophic denitrification device 30.

  The suspension organic matter separation device 10 can be configured by any of a precipitation device, a coagulation precipitation device, a flotation separation device, a screen device, a membrane separation device, a cyclone device, a mechanical separation device such as a screw press or a decanter, A combination of these plural devices is also possible.

  Nitrite treatment is a treatment in which ammonia nitrogen is oxidized to nitrite nitrogen by autotrophic microorganisms (autotrophic nitrite bacteria) on water to be treated containing ammonia. is there.

Anaerobic ammonia oxidation treatment is an anaerobic ammonia oxidation treatment using anaerobic microorganisms (autotrophic denitrifying bacteria) under anaerobic conditions using ammonia nitrogen as an electron donor and nitrite nitrogen as an electron acceptor. As shown by the following formula, this is a process for converting 1 equivalent of ammonia nitrogen and about 1.3 equivalents of nitrite nitrogen into nitrogen molecules by denitrification reaction.
NH ₄ ⁺ + 1.32NO ₂ ⁻ + 0.066HCO ₃ ⁻ + 0.13H ⁺ →
1.02N ₂ + 0.26NO ₃ ⁻ + 0.066CH ₂ O _0.5 N _0.15 + 2.03H ₂ O

  Until now, it has not been possible to achieve an efficient and anaerobic ammonia oxidation treatment for wastewater with a low ammonia concentration. In an atmosphere where the ammonia concentration is low, it is not possible to stabilize the regulation of the nitritation to proceed by suppressing nitrification of ammonia, and in the partial nitritation that nitrites about half of the ammonia, the remaining ammonia This is because the amount adjustment could not be stabilized.

  According to the said processing system, the separation liquid from which the suspension organic substance was isolate | separated from the to-be-processed water by the suspension organic substance separation apparatus 10 provided in the front | former stage of the autotrophic denitrification apparatus 30 is the autotrophic denitrification apparatus 30. To be supplied. The suspended organic matter separated from the water to be treated by the suspended organic matter separator 10 is anaerobically digested by the sludge anaerobic digester 40 to obtain a digested liquid in which ammonia nitrogen is concentrated.

  Even if the concentration of ammonia-nitrogen in the separated liquid from which the suspended organic substance is separated by the suspended organic substance separating apparatus 10 is low, such digested liquid is transferred to the autotrophic denitrifying apparatus 30 via the first transfer path R1. By supplying the autotrophic denitrification apparatus 30 with a high free ammonia concentration (FA), the activity of nitrifying bacteria is suppressed, and nitritation by nitrifying bacteria preferentially proceeds. As a result, the anaerobic ammonia oxidation treatment is efficiently performed.

  It is preferable to adjust the free ammonia concentration (FA) to 0.1-10 ppm, and by selectively suppressing the activity of nitrifying bacteria, it can be treated well even with water to be treated having an ammonia concentration of less than 100 ppm. Further, it is not necessary to suppress nitrifying bacteria by temperature control or pH control, and power costs and chemical costs can be saved.

  The concentration of free ammonia is obtained by measuring the ammonium ion concentration of the water to be treated by a diaphragm type ion electrode method or the like, and calculating by the formula of Anthonisen et al. Can be adopted.

  As the autotrophic denitrification device 30, a tandem nitrification tank that performs nitritation and an ammonia oxidation tank that performs anaerobic ammonia oxidation are arranged in series, or one tank such as Canon or SNAP. An equational configuration can be employed. The method called Canono converts about half of the inflowing ammonia to nitrite by the action of ammonia oxidizing bacteria by supplying a small amount of oxygen to the Sequential Bach Reactor (SBR), and advances the removal of ammonia in one tank. Is the method. A method called SNAP is an ammonia-treated material in which a fungus group containing autotrophic denitrifying bacteria that anaerobically oxidize ammonia is attached and immobilized on a carrier, and a fungus group containing ammonia-oxidizing bacteria is attached and immobilized on the outer surface of the fungus group Is a method of removing ammonia by contacting the wastewater with ammonia.

  There is also a method in which ammonia is removed by allowing a carrier in which ammonia-oxidizing bacteria and autotrophic denitrifying bacteria are comprehensively immobilized to flow in a reaction tank and adjusting dissolved oxygen to a range that does not inhibit the denitrifying reaction.

  In other words, by the treatment system, water to be treated containing suspending organic matter and ammonia is subjected to nitritation treatment that oxidizes ammonia to nitrous acid by autotrophic microorganisms under aerobic conditions, and under anaerobic conditions. A treatment method for nitrogen-containing organic wastewater, which is subjected to autotrophic denitrification treatment by anaerobic ammonia oxidation treatment using ammonia nitrogen as an electron donor and nitrite nitrogen as an electron acceptor by autotrophic microorganisms, Before the autotrophic denitrification treatment, the suspension organic matter separation treatment is performed to separate the suspension organic matter from the water to be treated, and the suspension organic matter separated by the suspension organic matter separation treatment is anaerobically digested. Then, a digestion solution is supplied to the autotrophic denitrification treatment, and a method for treating nitrogen-containing organic wastewater is performed.

  FIG. 2 shows a processing system according to the second embodiment. In the treatment system, the above-described autotrophic denitrification device 30 is anaerobic to the nitritation device 30A that performs nitritation treatment on the water to be treated and the water to be treated on which nitritation treatment has been performed. It is comprised by the two tank series type of the anaerobic ammonia oxidation apparatus 30B which performs a typical ammonia oxidation process.

  In this case, the path for supplying the digested liquid of the sludge anaerobic digester 40 to the nitritation apparatus 30A is the first transfer path R1. Furthermore, the path for supplying the digested liquid of the sludge anaerobic digester 40 to the anaerobic ammonia oxidizer 30B is the second transfer path R2.

  By configuring the autotrophic denitrification device 30 as a two-tank system of a nitritation device 30A and an anaerobic ammonia oxidation device 30B, the digested liquid is supplied to the nitritation device 30A through the first transfer path R1, 2 is supplied to the anaerobic ammonia oxidation apparatus 30B by the transfer path R2.

  Even if the nitrite nitrogen and ammonia nitrogen in the nitrification solution partially nitritized in the nitritation device 30A are significantly different from the appropriate ratio, the ammonia nitrogen concentration of the sludge anaerobic digester 40 Is supplied to the anaerobic ammonia oxidizer 30B through the second transfer path R2, so that the ammonia concentration and nitrous acid concentration in the anaerobic ammonia oxidizer 30B are set to appropriate values, for example, 1: 1.3 to 1 .4, and anaerobic ammonia oxidation can be efficiently advanced.

  That is, in addition to the above-described method for treating nitrogen-containing organic wastewater, the nitritation treatment and the anaerobic ammonia oxidation treatment are independent treatment steps, and the digested liquid is treated with the nitritation treatment and the anaerobic treatment. A method for treating nitrogen-containing organic wastewater is carried out, characterized in that it is distributed and fed to an active ammonia oxidation treatment.

  FIG. 3 shows the processing system of the third aspect. The said processing system carries out the denitrification process which reduces nitrite nitrogen and nitrate nitrogen to a nitrogen molecule by heterotrophic denitrification microorganisms in 1st transfer path | route R1 of the processing system of the 1st aspect mentioned above. The denitrification device 20 is disposed, and a third transfer path R <b> 3 for supplying the treatment liquid of the autotrophic denitrification device 30 to the heterotrophic denitrification device 20 is provided.

  The treatment liquid of the sludge anaerobic digester 40 is supplied to the heterotrophic denitrification apparatus 20 by the first transfer path R1, and a part of the treatment liquid of the autotrophic denitrification apparatus 30 is heterotrophic by the third transfer path R3. By returning to the denitrification apparatus 20, mainly the soluble organic substances contained in the digestion liquid of the sludge anaerobic digestion apparatus 40 are used as electron donors, and the nitrate state contained in the treatment liquid of the autotrophic denitrification apparatus 30. By performing the denitrification treatment with the heterotrophic denitrification microorganism using nitrogen as an electron acceptor, the amount of nitric acid discharged out of the system from the autotrophic denitrification apparatus 30 can be reduced.

  If the water to be treated supplied to the autotrophic denitrification apparatus 30 contains a large amount of soluble organic matter, oxygen required for the nitritation treatment is consumed in the decomposition treatment of the soluble organic matter, and the nitritation treatment Decreases the efficiency.

  Dissolved organic matter contained in the digested liquid of the sludge anaerobic digester 40 is decomposed by the heterotrophic denitrification device 20, and the water to be treated whose dissolved organic matter concentration is lowered by the heterotrophic denitrification device 20 is independent. Since it is supplied to the nutritional denitrification apparatus 30, the treatment of autotrophic microorganisms that perform nitritation to oxidize ammonia nitrogen to nitrite nitrogen is not hindered and can be treated efficiently. It becomes like this.

  In addition to the method for treating nitrogen-containing organic wastewater according to the first aspect described above, heterotrophicity in which nitrite nitrogen and nitrate nitrogen are reduced to nitrogen molecules by heterotrophic denitrifying microorganisms with respect to the digested liquid. A denitrification process is performed, and the treatment liquid that has been subjected to the heterotrophic denitrification process is supplied to the autotrophic denitrification process, and a process liquid by the autotrophic denitrification process is supplied to the heterotrophic denitrification process The processing method of the nitrogen-containing organic wastewater characterized by this is realized.

  FIG. 4 shows a processing system according to the fourth aspect. The said processing system carries out the denitrification process which reduces nitrite nitrogen and nitrate nitrogen to a nitrogen molecule by heterotrophic denitrification microorganisms in 1st transfer path | route R1 of the processing system of the 2nd aspect mentioned above. The denitrification device 20 is disposed, and a third transfer path R3 for supplying the treatment liquid of the anaerobic ammonia oxidation device 30B to the heterotrophic denitrification device 20 is provided.

  The treatment liquid of the sludge anaerobic digester 40 is supplied to the heterotrophic denitrification apparatus 20 through the first transfer path R1, and a part of the treatment liquid of the anaerobic ammonia oxidation apparatus 30B is heterotrophic dehydrated through the third transfer path R3. By returning to the nitrogenation apparatus 20, mainly the soluble organic substances contained in the digestion liquid of the sludge anaerobic digestion apparatus 40 are used as electron donors, and nitrate nitrogen contained in the treatment liquid of the anaerobic ammonia oxidation apparatus is converted into electrons. By performing the denitrification treatment with the heterotrophic denitrifying microorganism as the acceptor, the amount of nitric acid discharged out of the system from the anaerobic ammonia oxidizing apparatus 30B can be reduced.

  If the water to be treated supplied to the nitritation apparatus 30A contains a large amount of soluble organic matter, oxygen required for nitritation is consumed for the decomposition of the soluble organic matter, and the efficiency of the nitritation treatment is improved. descend. Dissolved organic substances contained in the digested liquid of the sludge anaerobic digester 40 are decomposed by the heterotrophic denitrification apparatus 20, and the water to be treated whose concentration of soluble organic substances is lowered by the heterotrophic denitrification apparatus 20 is sublimated. Since it is supplied to the nitrification apparatus 30A, the treatment of autotrophic microorganisms that perform nitritation to oxidize ammonia nitrogen to nitrite is not hindered and can be efficiently processed. Become.

  In addition to the treatment method of the second aspect described above, the digestive juice is subjected to heterotrophic denitrification treatment for reducing nitrite nitrogen and nitrate nitrogen to nitrogen molecules by heterotrophic denitrifying microorganisms, A nitrogen-containing organic material, characterized in that a treatment liquid subjected to heterotrophic denitrification treatment is supplied to the nitritation treatment, and a treatment liquid obtained by the anaerobic ammonia oxidation treatment is supplied to the heterotrophic denitrification treatment. Waste water treatment methods are implemented.

  As shown in FIG. 5, when the ammonia nitrogen concentration of the water to be treated introduced into the wastewater treatment system is less than 100 ppm, the BOD ratio to the ammonia nitrogen concentration of the water to be treated is preferably larger than 3.0. In particular, it is more preferable that the ratio of the suspending organic substance concentration is larger. This is because the ammonia recovery efficiency in the sludge anaerobic digester 40 is improved, and the adjustment of the free ammonia concentration in the autotrophic denitrifier 30 is facilitated. The nitritation can also be stabilized by adjusting the BOD ratio with respect to the ammonia nitrogen concentration of the separation liquid of the suspending organic matter separation apparatus 10 to a range larger than 0.5 and smaller than 2.0.

In the autotrophic denitrification apparatus 30, the dissolved oxygen concentration is controlled to an appropriate range by adjusting the amount of aeration. However, when the ammonia nitrogen concentration is less than 100 ppm, the dissolved oxygen concentration is increased by a slight change in the amount of aeration air. It will fluctuate. Even in such a case, by adjusting BOD / NH ₃ —N to a value larger than 0.5, large fluctuations in the dissolved oxygen concentration due to consumption of oxygen by BOD can be suppressed. Incidentally, increasing the aeration amount when BOD / _NH 3 -N exceeds 2.0, undesirable from the viewpoint of energy saving.

  The adjustment of the aeration amount can be performed by a method based on the measured values of the ammonium ion concentration and the nitrite ion concentration, or a combination of these methods, in addition to the method based on the measured value of the dissolved oxygen concentration.

  Thus, according to the present invention, anaerobic ammonia oxidation treatment can be applied to wastewater having a low ammonia concentration such as sewage that has not been realized in the past.

  The amount of electricity used at the sewage treatment plant is about 6.3 billion kWh (FY 2004), accounting for 0.7% of the amount of electricity used in Japan, and equivalent to the amount of electricity consumed in Uruguay and Jamaica. Among them, the power consumption of the aeration blower accounts for 25-30%. By applying the anaerobic ammonia oxidation treatment, which theoretically requires only 43% of the amount of oxygen of the conventional complete nitrification treatment to the sewage treatment, the present invention can produce a great power saving effect and greatly contribute to the reduction of greenhouse gases. is there.

  Each of the above-described embodiments is an example of the present invention, and the present invention is not limited by the description. The specific configuration of each part can be appropriately designed within the range where the effects of the present invention are exhibited. Needless to say.

10: Suspended organic matter separation device 20: Dissolved organic matter decomposition device 30: Autotrophic denitrification device 30A: Nitrite device 30B: Anaerobic ammonia oxidation device 40: Sludge anaerobic digester R1: First transfer route R2 : Second transfer route R3: third transfer route R4: fourth transfer route

Claims (9)

Nitritating treatment of water to be treated containing suspended organic matter and ammonia under the aerobic condition by oxidation of ammonia to nitrous acid by an autotrophic microorganism, and the ammonia state by the autotrophic microorganism under anaerobic conditions A nitrogen-containing organic wastewater treatment system having an autotrophic denitrification device that performs denitrification treatment by anaerobic ammonia oxidation treatment using nitrogen as an electron donor and nitrite nitrogen as an electron acceptor,
A suspending organic matter separation device that separates the suspending organic matter from the water to be treated is provided upstream of the autotrophic denitrification device, and the suspending organic matter separated by the suspending organic matter separation device is anaerobically digested A treatment system for nitrogen-containing organic wastewater, comprising a sludge anaerobic digester and a first transfer path for supplying digested liquid of the sludge anaerobic digester to the autotrophic denitrifier.   The autotrophic denitrification device includes a nitritation device that performs the nitritation treatment on the water to be treated, and the anaerobic ammonia oxidation treatment on the water to be treated on which the nitritation treatment has been performed. An anaerobic ammonia oxidizer to perform, wherein the first transfer path is a path for supplying a digested liquid of the sludge anaerobic digester to the nitritation apparatus, and the digested liquid of the sludge anaerobic digester is The nitrogen-containing organic wastewater treatment system according to claim 1, further comprising a second transfer path that supplies the anaerobic ammonia oxidation apparatus.   A heterotrophic denitrification apparatus that performs denitrification treatment for reducing nitrite nitrogen and nitrate nitrogen to nitrogen molecules by a heterotrophic denitrifying microorganism is disposed in the first transfer path, and the autotrophic denitrification apparatus The nitrogen-containing organic wastewater treatment system according to claim 1, further comprising a third transfer path for supplying the treatment liquid to the heterotrophic denitrification apparatus.   A heterotrophic denitrification device that performs denitrification treatment for reducing nitrite nitrogen and nitrate nitrogen to nitrogen molecules by heterotrophic denitrifying microorganisms is disposed in the first transfer path, and the anaerobic ammonia oxidation device The nitrogen-containing organic wastewater treatment system according to claim 2, further comprising a third transfer path for supplying a treatment liquid to the heterotrophic denitrification apparatus. The treated water is
1) NH ₃ —N (ammonia nitrogen concentration) <100 ppm
_{2) BOD / NH 3 -N>} 3.0
The separation liquid of the suspending organic matter separation device is
_{3) 0.5 <BOD / NH 3} -N <2.0
The nitrogen-containing organic wastewater treatment system according to any one of claims 1 to 4, wherein: Nitritating treatment of water to be treated containing suspended organic matter and ammonia under the aerobic condition by oxidation of ammonia to nitrous acid by an autotrophic microorganism, and the ammonia state by the autotrophic microorganism under anaerobic conditions A method for treating nitrogen-containing organic wastewater, which performs autotrophic denitrification treatment by anaerobic ammonia oxidation treatment using nitrogen as an electron donor and nitrite nitrogen as an electron acceptor,
Before the autotrophic denitrification treatment, the suspension organic matter separation treatment is performed to separate the suspension organic matter from the water to be treated, and the suspension organic matter separated by the suspension organic matter separation treatment is anaerobically digested. And a digestion solution is supplied to the autotrophic denitrification treatment, wherein the nitrogen-containing organic wastewater is treated.   7. The nitritation treatment and the anaerobic ammonia oxidation treatment are independent processing steps, and the digested liquid is distributed and supplied to the nitritation treatment and the anaerobic ammonia oxidation treatment. The processing method of nitrogen-containing organic wastewater as described.   The digested liquid is subjected to heterotrophic denitrification treatment for reducing nitrite nitrogen and nitrate nitrogen to nitrogen molecules by heterotrophic denitrifying microorganisms, The method for treating nitrogen-containing organic wastewater according to claim 6, wherein the nitrogen-containing organic wastewater is supplied to the autotrophic denitrification treatment, and a treatment solution obtained by the autotrophic denitrification treatment is supplied to the heterotrophic denitrification treatment.   The digested liquid is subjected to heterotrophic denitrification treatment for reducing nitrite nitrogen and nitrate nitrogen to nitrogen molecules by heterotrophic denitrifying microorganisms, The method for treating nitrogen-containing organic wastewater according to claim 7, wherein the nitrogen-containing organic wastewater is supplied to the nitritation treatment, and a treatment solution obtained by the anaerobic ammonia oxidation treatment is supplied to the heterotrophic denitrification treatment.