JP2016107219A - Nitrogen treatment method and nitrogen treatment apparatus - Google Patents

Abstract

The present invention provides a nitrogen treatment apparatus and a nitrogen treatment method for stably removing nitrogen components contained in wastewater even when the concentration of ammoniacal nitrogen in the wastewater is increased or the water temperature is lowered. SOLUTION: A process of nitrifying high-concentration ammonia nitrogen wastewater by a nitrifying bacteria group to proliferate high-concentration ammonia-resistant bacteria (AH bacteria) contained in the nitrifying bacteria group, and utilizing the proliferated AH bacteria A nitrogen treatment method including a step of performing nitrification treatment of waste water and a step of performing denitrification treatment of waste water subjected to nitrification treatment. The nitrogen treatment apparatus 1 includes an aerobic tank 14 that performs nitrification treatment of wastewater, an anoxic tank 12 that performs denitrification treatment of wastewater that has undergone nitrification treatment, and high-concentration ammonia nitrogen wastewater by nitrifying bacteria. A nitrogen treatment apparatus comprising: a sub-aerobic tank 30 that performs nitrification and propagates AH bacteria contained in a group of nitrifying bacteria, and performs nitrification treatment of wastewater using the propagated AH bacteria. [Selection] Figure 1

Description

  The present invention relates to a nitrogen treatment method and a nitrogen treatment apparatus for biologically removing nitrogen components contained in wastewater.

  Domestic wastewater and industrial wastewater may contain inorganic nitrogen and organic nitrogen such as ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen. These nitrogen components cause eutrophication of lakes, rivers, etc. and a decrease in dissolved oxygen concentration, and cause water pollution. Done.

  As the nitrogen removal method, when the nitrogen concentration of the wastewater is low, various nitrogen removal methods such as an ion exchange method, an adsorption method, a discontinuous point chlorine addition method, and an ozone oxidation method can be used. Is possible. However, in sewage treatment facilities that treat sewage and rainwater such as domestic wastewater and industrial wastewater, biological treatment by microorganisms is generally adopted, and nitrogen removal treatment is combined with decomposition treatment of various organic substances contained in sewage. Has been made.

  As a processing format of sewage treatment, there is a method of performing aerobic treatment and anaerobic treatment in combination. In the aerobic treatment, aerobic decomposition of various organic substances by aerobic microorganisms, ammonia oxidizing bacteria (Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosolobus, etc.) and nitrite oxidizing bacteria (Nitrobactor, Nitrospina, etc.) contained in the aerobic microorganisms Nitrococcus, Nitrospira, etc.) are used to oxidize ammonia nitrogen and nitrite nitrogen. In anaerobic treatment, anaerobic microorganisms anaerobically decompose various organic substances, and heterotrophic bacteria (such as Pseudomonas denitrificans) contained in anaerobic microorganisms convert nitrate nitrogen and nitrite nitrogen to molecular nitrogen. A denitrification treatment for reduction is performed.

In a sewage treatment facility that removes nitrogen by such nitrification and denitrification, the aerobic tank in which nitrification is performed is usually within a load range of 0.2 to 0.3 kg-N / m ³ / day. The anaerobic tank that is operated and subjected to denitrification is operated in a load range of 0.2 to 0.4 kg-N / m ³ / day. In order to sufficiently perform an average sewage nitrogen removal treatment in which the total nitrogen concentration is about 30 to 40 mg / L, the residence is about 6 to 8 hours for the aerobic tank and about 5 to 8 hours for the anaerobic tank. Since it is necessary to secure time, it is a treatment format that requires a treatment tank scale, aeration power, and the like as compared with the standard activated sludge method and the like.

  In some cases, a sewage treatment facility is provided with a sludge treatment system in addition to a sewage treatment system that performs biological treatment of water to be treated. In the sludge treatment system, surplus sludge generated during biological treatment is converted into organic materials or waste through digestion treatment, dehydration treatment, and the like. The sludge dehydrated filtrate generated after the dehydration treatment contains a large amount of nitrogen components and is usually returned to the sewage treatment system and reprocessed. Since the returned sludge dehydrated filtrate increases the nitrogen load of the water to be treated and causes a reduction in the speed and stability of the nitrogen removal treatment, a technique for appropriately treating the sludge dehydrated filtrate has been studied.

  For example, in Patent Document 1, sludge containing organic substances is supplied to a reaction tank (3) composed of an anaerobic tank (1) and an aerobic tank (2) to decompose the organic substances, and an anaerobic digester (8). In the sludge treatment system that temporarily stores the dehydrated filtrate that has been subjected to solid-liquid separation in the dehydrator (9) in the adjustment tank (10), after the anaerobic digestion process in the dehydrator (9), intermittently after the adjustment tank (10) A nitrification tank (13) provided with an aeration system (11) and a stirrer (12), and an extraction pump (15) for extracting the supernatant of the nitrification tank (13) to the anoxic tank (1); A nitrogen removal system for dehydrated filtrate in which an exchange pump (14) for exchanging sewage in the nitrification tank (13) and sewage in the anoxic tank (1) is disclosed.

JP 2012-157837 A

  Ammonia-oxidizing bacteria responsible for nitrification of wastewater have a characteristic that the growth rate is extremely slow, and the ammonia oxidation reaction is the rate-limiting step in a series of nitrogen removal treatments. Once the activity of the ammonia-oxidizing bacteria is reduced, the denitrification process does not proceed until the nitrification activity is restored again, and a stable nitrogen removal process becomes difficult. Therefore, it is important to maintain the activity of ammonia oxidizing bacteria at a high level in order to improve the speed and stability of the nitrogen removal treatment and improve the equipment efficiency such as the treatment tank scale and aeration power.

  However, the activity by ammonia oxidizing bacteria has a characteristic that it is easily affected by fluctuations in the properties of wastewater. For example, it is known that the activity of ammonia-oxidizing bacteria is inhibited when the concentration of ammoniacal nitrogen in wastewater is increased by returning sludge dehydrated filtrate from the sludge treatment system. According to the technique disclosed in Patent Document 1, it is said that nitrogen contained in the sludge dehydrated filtrate can be removed by the nitrification tank disposed in the subsequent stage of the adjustment tank. It does not directly contribute to the nitrification treatment in the aerobic tank. For this reason, when applied to nitrogen removal treatment of wastewater in a sewage treatment facility or the like, it is not possible to appropriately cope with fluctuations in properties of treated water introduced into a sewage treatment system or the like.

  In addition, it is known that the activity of ammonia oxidizing bacteria is greatly reduced in a low water temperature environment. For example, when the temperature of the water to be treated becomes a low temperature of less than 20 ° C. in winter, the activity of ammonia oxidizing bacteria is remarkably reduced and sufficient nitrification treatment cannot be performed, and the subsequent denitrification treatment proceeds. Therefore, there is a problem that the nitrogen removal treatment cannot be performed. Therefore, there is a need for a technique that can stably perform nitrogen removal treatment regardless of changes in properties such as ammonia nitrogen concentration and water temperature of wastewater.

  Accordingly, an object of the present invention is to provide a nitrogen treatment apparatus and a nitrogen treatment method capable of stably removing nitrogen components contained in wastewater even when the concentration of ammoniacal nitrogen in the wastewater is increased or the water temperature is lowered. And

  In order to solve the above problems, a nitrogen treatment method according to the present invention is a nitrogen treatment method for biologically removing nitrogen components contained in wastewater, and ammonia nitrogen having a concentration higher than that of the wastewater by nitrifying bacteria. Nitrifying treatment of high-concentration ammonia nitrogen wastewater containing, and a step of growing a high-concentration ammonia-resistant bacterium (AH bacterium) contained in the nitrifying bacteria group, and using the proliferated AH bacterium, The method includes a step of performing nitrification treatment of wastewater, and a step of performing denitrification treatment of the wastewater subjected to the nitrification treatment.

  Further, the nitrogen treatment apparatus according to the present invention is a nitrogen treatment apparatus that biologically removes nitrogen components contained in wastewater, wherein an aerobic tank that performs nitrification treatment of the wastewater and the nitrification treatment are performed. Included in the nitrifying bacteria group, an anoxic tank that performs denitrification treatment of wastewater, and nitrification treatment of high-concentration ammoniacal nitrogen wastewater containing ammonia nitrogen at a higher concentration than the wastewater by the nitrifying bacteria group A secondary aerobic tank for growing high-concentration ammonia-resistant bacteria (AH bacteria), and performing nitrification treatment of the wastewater using the grown AH bacteria.

  According to the present invention, it is possible to provide a nitrogen treatment apparatus and a nitrogen treatment method capable of stably removing nitrogen components contained in wastewater even when the concentration of ammoniacal nitrogen in the wastewater is increased or the water temperature is lowered. .

It is a lineblock diagram showing an example of a nitrogen treatment device concerning a 1st embodiment of the present invention. It is a block diagram which shows an example of the nitrogen processing apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram which shows an example of the nitrogen processing apparatus which concerns on 3rd Embodiment of this invention. It is a block diagram which shows an example of the nitrogen processing apparatus which concerns on 4th Embodiment of this invention. It is a block diagram which shows an example of the nitrogen processing apparatus which concerns on 5th Embodiment of this invention. It is a figure which shows the change of the nitrogen concentration of the to-be-processed water to which the wastewater treatment method which concerns on an Example is applied. It is a figure which expands and shows the change of the nitrogen concentration of the to-be-processed water to which the waste water treatment method which concerns on an Example is applied.

[Nitrogen treatment method]
First, a nitrogen treatment method according to an embodiment of the present invention will be described.

  The nitrogen treatment method according to this embodiment is a nitrogen treatment method that biologically removes nitrogen components contained in wastewater. In this nitrogen treatment method, waste water containing at least ammonia nitrogen as a nitrogen component is treated as water to be treated, and the nitrogen component contained in the waste water is converted into molecular nitrogen by nitrification treatment and denitrification treatment to remove nitrogen. . In the nitrification treatment, in particular, a nitrogen treatment method utilizing the activity of highly concentrated ammonia-resistant bacteria (AH bacteria).

In general, the nitrifying bacteria included in activated sludge, etc. include ammonia oxidizing bacteria that oxidize ammonia nitrogen to nitrite nitrogen, and nitrite oxidizing bacteria that oxidize nitrite nitrogen to nitrate nitrogen. It is included. Furthermore, ammonia-oxidizing bacteria are resistant to high concentrations of ammonia, are highly sensitive to high concentrations of ammonia-resistant bacteria (AH bacteria) that exhibit higher activity in the presence of high concentrations of ammonia, and are sensitive to high concentrations of ammonia. It is known to be classified as a low-concentration ammonia-oxidizing bacterium (AL fungus) that exhibits higher activity in the presence of ammonia (publication: Y. Suwa, Y. Imamura, T. Suzuki, T. Tashiro, Y. Urushigawa, Ammonium-oxidizing bacteria with different sensitivities to (NH ₄ ) ₂ SO ₄ in activated sludges, Water Res. 28 (1994) 1523-1532).

  For example, in the form of microorganism immobilization, ammonia-oxidizing bacteria detected by culturing in a high-concentration ammonia sulfate solution having a concentration of 5000 mg / L for 8 weeks in AH bacteria and a low-concentration ammonia sulfate solution having a concentration of 100 mg / L Ammonia-oxidizing bacteria detected after culturing for 8 weeks can be classified as AL bacteria (see JP-A-9-47788, JP-A-9-75984, etc.).

  In general, in the nitrogen removal treatment of wastewater having a low ammonia nitrogen concentration of about 20 mg / L to 60 mg / L such as sewage, AL bacteria preferentially proliferate and show high nitrification activity, while AH bacteria Does not show good growth and has low nitrification activity. Therefore, in the conventional nitrogen removal treatment, nitrification treatment of water to be treated is mainly performed by the contribution of AL bacteria. On the other hand, when the concentration of ammonia nitrogen in the environment increases, the growth rate of AH bacteria increases and shows high nitrification activity, while the growth rate of AL bacteria decreases and does not show nitrification activity. It is known. Although AH bacteria have a low affinity for ammonia, they exhibit the property that the nitrification rate is increased by increasing the ammoniacal nitrogen concentration. Therefore, at a certain concentration or higher, AH bacteria preferentially bear the nitrification treatment.

  As described above, the AH bacterium used in the nitrogen treatment method according to the present embodiment has an advantage that the activity is hardly lowered even if there is a fluctuation in which the ammoniacal nitrogen concentration of the water to be treated increases. In addition, AH bacteria exhibit activity even when the environmental water temperature is low, for example, at a water temperature of 7 ° C., and in an environment where the water temperature is low, the ammoniacal nitrogen concentration decreases to about 20 mg / L to 60 mg / L. However, it was newly found to retain activity. Therefore, in the nitrogen treatment method according to this embodiment, the AH bacteria contained in the nitrifying bacteria group are propagated and used for the nitrification treatment of the wastewater, thereby making the ammonia of the wastewater more than the conventional nitrogen removal treatment by the AL bacteria. It was possible to realize nitrification treatment that is less susceptible to the effects of increased nitrogen concentration and decreased water temperature.

  Specifically, the nitrogen treatment method according to the present embodiment is a method including a high concentration nitrification treatment step, a low concentration nitrification treatment step, and a denitrification treatment step. Each of these steps can be repeated continuously in this order, and is usually performed in a treatment tank that performs biological treatment for removing nitrogen from the wastewater.

  The waste water (treated water) subjected to nitrogen removal treatment in this nitrogen treatment method is waste water containing at least ammonia nitrogen, and other inorganic nitrogen such as nitrite nitrogen, nitrate nitrogen, organic nitrogen, Other organic substances may be contained. For example, sewage including sewage such as domestic wastewater and industrial wastewater, rainwater, or mixed sewage obtained by combining them can be suitably applied as the water to be treated. Such sewage generally has an ammoniacal nitrogen concentration of less than 100 mg / L, often in the order of 20 mg / L to 60 mg / L. The temperature of the waste water (treated water) subjected to nitrogen removal treatment can be applied in the range of normal temperature (5 ° C. to 35 ° C.), in the temperature range of 10 ° C. to 20 ° C. In any case, it is possible to apply this nitrogen treatment method.

  In the high-concentration nitrification treatment step, nitrification treatment of high-concentration ammoniacal nitrogen wastewater containing ammoniacal nitrogen at a higher concentration than the wastewater is performed by the nitrifying bacteria group to proliferate AH bacteria contained in the nitrifying bacteria group. High-concentration ammoniacal nitrogen wastewater is a wastewater that is different from the wastewater to be nitrogen-removed (treated water). By performing nitrification treatment of high-concentration ammonia nitrogen wastewater with nitrifying bacteria, the number of AH bacteria and nitrification activity can be improved as compared with conventional nitrogen removal treatment of wastewater.

  The nitrification treatment of high-concentration ammonia nitrogen wastewater can be performed by, for example, an aerobic treatment using an aerobic microorganism group such as activated sludge containing a nitrifying bacteria group. As high-concentration ammonia nitrogen wastewater, any suitable wastewater can be used as long as it contains ammonia nitrogen at a higher concentration than the water to be treated. For example, sludge dehydrated filtrate after anaerobic digestion treatment, scrubber wastewater for ammonia, Various inorganic nitrogen wastewater such as semiconductor cleaning wastewater can be applied. Among these, a sludge dehydrated filtrate after anaerobic digestion treatment having a water temperature suitable for the growth of nitrifying bacteria and an inorganic carbon source is preferable. The temperature condition of the nitrification treatment is preferably about 30 ° C. to 37 ° C., but is not particularly limited. Further, the treatment time of the nitrification treatment can be set to an appropriate time, and it is not necessary to nitrify substantially the entire amount of ammonia nitrogen contained in the high concentration ammonia nitrogen waste water.

  The ammonia nitrogen concentration of the high-concentration ammonia nitrogen wastewater is at least 100 mg / L or more, preferably 160 mg / L or more, more preferably 200 mg / L or more, and further preferably 400 mg / L or more. The AL bacteria reach the maximum activity and the maximum number of bacteria in the region where the ammoniacal nitrogen concentration is 100 mg / L or less, and the ammonia and nitrogen counts exceeding the region tend to decrease in activity and the number of bacteria. In the form of microorganism immobilization, when the ammoniacal nitrogen concentration reaches around 400 mg / L, the number of bacteria decreases by about two orders of magnitude, and the nitrification activity is not substantially exhibited. In contrast, AH bacteria tend to grow logarithmically until the ammoniacal nitrogen concentration reaches around 400 mg / L and improve the activity to reach a steady state. Therefore, if the ammonia nitrogen concentration is 100 mg / L or more, AH bacteria continue to grow until they reach a steady state as the ammonia nitrogen concentration increases, regardless of whether the microorganism is immobilized. Can be used effectively.

  The nitrifying bacteria group used for nitrification treatment in the high concentration nitrification treatment step is preferably used after being immobilized in the form of an immobilization carrier or a contact filter medium. The nitrifying bacteria group to be immobilized may be separated from a microorganism group such as activated sludge, or may be a microorganism group in which ammonia-oxidizing bacteria are preferentially propagated. The immobilization carrier may be either an immobilization immobilization carrier in which ammonia-oxidizing bacteria are inclusively immobilized inside the carrier or an adhering immobilization carrier that is adhering and immobilized on the surface of the carrier. The inclusion immobilization carrier is advantageous in that the management of sludge can be simplified at the time of acclimatization.

  As the immobilization material, for example, a suitable carrier such as a gel carrier such as polyvinyl alcohol, alginic acid, or polyethylene glycol, or a plastic carrier such as cellulose, polyester, polypropylene, or vinyl chloride can be used. Further, as the shape of the immobilization carrier, those formed into a spherical shape, a cylindrical shape, a cubic shape, a porous shape, a honeycomb shape, a sponge shape or the like are suitable. As the contact filter medium, a vinyl chloride filter medium or a polyethylene filter medium is suitable. It is also possible to use granules utilizing self-granulation of microorganisms. The amount of the carrier for immobilization is preferably 10% or more and 40% or less, more preferably 15% or more and 25% or less per treatment tank.

  In the low concentration nitrification treatment step, waste water is nitrified using the AH bacteria grown in the high concentration nitrification treatment step. This low-concentration nitrification process uses AH bacteria to perform nitrification treatment that has been conventionally performed on wastewater (treated water), thereby removing ammonia nitrogen contained in the treated water. It converts to nitrite nitrogen or nitrate nitrogen. Even if the concentration of ammoniacal nitrogen in the water to be treated increases or the water temperature decreases by using AH bacteria in a mixture of aerobic microorganisms used in nitrification treatment Ammonia nitrogen contained in water can be stably nitrified.

  In nitrification of water to be treated, after the AH bacteria grown are directly added to or flown into an aerobic treatment tank that performs nitrification treatment, or after being added or flown into the front side of such a treatment tank You may make it flow into an aerobic processing tank indirectly. Alternatively, the treated water may be directly supplied to the grown AH bacteria and brought into contact therewith. In any case, by using a group of nitrifying bacteria containing the proliferated AH bacteria, the AH bacteria can be used preferentially in a high ammonia nitrogen concentration region, and a low concentration region. Then, AL bacteria can be used preferentially. Therefore, it is possible to more stably nitrify wastewater (treated water) whose ammonia nitrogen concentration varies over a wide range.

  In the denitrification treatment step, denitrification treatment of wastewater that has been nitrified using AH bacteria is performed. In this denitrification treatment process, nitrite nitrogen and nitrate nitrogen contained in waste water (treated water) after nitrification treatment by anaerobic microorganisms by performing denitrification treatment that has been generally performed conventionally. Is converted to molecular nitrogen. Even if the ammonia nitrogen concentration in the water to be treated increases or the water temperature decreases, AH bacteria perform nitrification at a high nitrification rate in the low concentration nitrification treatment step. The water to be treated converted to nitrite nitrogen or nitrate nitrogen is denitrified, and nitrogen components can be stably removed at a high nitrogen removal rate.

[Nitrogen Treatment Apparatus: First Embodiment]
Next, the nitrogen treatment apparatus according to the first embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the common part in each following figure, and the description about the overlapping part is abbreviate | omitted.

  FIG. 1 is a configuration diagram showing an example of a nitrogen treatment apparatus according to the first embodiment of the present invention.

  As shown in FIG. 1, the nitrogen treatment apparatus 1 according to the first embodiment includes a sewage treatment system 10, a sludge treatment system 20, and a sub-aerobic tank 30. The nitrogen treatment device 1 is a device that removes nitrogen components contained in wastewater by biological treatment, and includes inorganic nitrogen such as ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, and organic nitrogen in the waste water. It has a function of converting and removing nitrogen components such as molecular nitrogen (nitrogen gas) by nitrification reaction and denitrification reaction. In this embodiment, the nitrogen treatment apparatus 1 is applied to a sewage treatment facility and sewage is treated as waste water. The nitrogen treatment apparatus 1 is an apparatus suitable for carrying out the above-described nitrogen treatment method. In particular, a sub-aerobic tank 30 for preferentially growing AH bacteria is independent of the sewage treatment system 10. It has the feature in being provided as.

  As shown in FIG. 1, the sewage treatment system 10 includes an anoxic tank 12 and an aerobic tank 14 as treatment tanks for performing biological treatment. In the sewage treatment system 10, the anaerobic tank 12 and the aerobic tank 14 are provided in series so that the anoxic tank 12 is on the front side and the aerobic tank 14 is on the back side. The treated sewage (raw water) introduced into the tank is treated in the anaerobic tank 12 and then flows into the aerobic tank 14, and is subsequently treated in the aerobic tank 14. The anaerobic tank 12 and the aerobic tank 14 are connected by a nitrifying liquid return pipe 100 so that the nitrating liquid treated in the aerobic tank 14 is returned to the anoxic tank 12.

  The anaerobic tank 12 is a sealed tank that performs anaerobic treatment of water to be treated with anaerobic microorganisms and denitrifies nitrogen components contained in the water to be treated. In the anaerobic tank 12, the anaerobic microorganism group containing the denitrifying bacteria group is held, and the denitrifying bacteria group performs a denitrification process. Further, stirring means such as mechanical stirring for stirring the water to be treated, air flow stirring, liquid flow stirring, heating means such as a boiler for heating the water to be treated, scum removing means, and the like can be provided.

  Anaerobic treatment is performed using anaerobic microorganisms under conditions where bound oxygen such as nitrite ions and nitrate ions is present while dissolved oxygen concentration is limited and free molecular oxygen is scarce . In anaerobic treatment, organic substances contained in the water to be treated are decomposed anaerobically, and nitrite nitrogen and nitrate nitrogen are reduced to molecular nitrogen by denitrifying bacteria contained in anaerobic microorganisms. Denitrification is done. The anaerobic microorganism group may have a form in which microorganisms are immobilized, and an appropriate type of treatment such as a fixed bed or a fluidized bed can be used. As a specific form of immobilization, the same immobilization as in the above-mentioned immobilization of nitrifying bacteria can be applied.

  The aerobic tank 14 is a treatment tank that performs aerobic treatment of water to be treated by an aerobic microorganism group and nitrifies ammoniacal nitrogen contained in the water to be treated. The aerobic tank 14 holds an aerobic microorganism group containing a nitrifying bacteria group. In addition, aeration means for aeration of the water to be treated is provided. This aerobic tank 14 is transferred with AH bacteria grown in the sub-aerobic tank 30 to be described later, and is responsible for nitrification treatment.

  The aerobic treatment is performed using an aerobic microorganism group under conditions where dissolved oxygen exists. In the aerobic treatment, organic substances contained in the water to be treated are aerobically decomposed, and ammonia nitrogen is oxidized to nitrite nitrogen and nitrate nitrogen by the nitrifying bacteria group contained in the aerobic microorganism group. Then, nitrification treatment is performed. The aerobic microorganism group may have a microorganism-immobilized form, and an appropriate type of treatment such as a fixed bed or a fluidized bed can be used. As a specific form of immobilization, the same immobilization as in the above-mentioned immobilization of nitrifying bacteria can be applied.

  Thus, sewage (raw water) as treated water flows into the sewage treatment system 10, and nitrification treatment and denitrification treatment are performed in the anoxic tank 12 and the aerobic tank 14. Then, the sewage from which the nitrogen component has been removed by nitrification and denitrification is transferred to the settling tank 22. In addition, if the sewage treatment system 10 is a structure which has at least the anoxic tank 12 and the aerobic tank 14 as a treatment tank which performs biological treatment, biological treatment of a to-be-treated water, adjustment of a property, etc. You may have the other processing tank to perform. Examples of such other treatment tanks include, for example, an anaerobic tank that performs anaerobic treatment under conditions where both free molecular oxygen and binding oxygen are scarce, and a re-aeration tank that performs re-decomposition treatment of organic substances on the subsequent stage side. Alternatively, an appropriate treatment tank such as an adjustment tank that adjusts the flow rate, pH, dissolved oxygen concentration, and the like of the water to be treated can be provided. In addition, the number and arrangement of each of the anaerobic tank 12, the aerobic tank 14, and the other processing tanks are not particularly limited, and any one of the processing tanks may be arranged in series, The order in which the tanks are arranged may be arbitrarily changed, and a flow path, a pipe line, and the like that connect the processing tanks to each other may be arbitrarily provided.

  As shown in FIG. 1, the sludge treatment system 20 is provided along with the sewage treatment system 10, and includes a sedimentation tank 22, a concentration part 24, a digestion tank 26, and a solid-liquid separation part 28. In the nitrogen treatment apparatus 1, the sludge treatment system 20 plays a role of treating excess sludge and supplying high-concentration ammoniacal nitrogen wastewater (ammonia wastewater 29) for growing AH bacteria.

  The sedimentation tank 22 is a treatment tank in which the sludge contained in the water to be treated that has undergone biological treatment is precipitated. The sedimentation tank 22 is provided on the rear stage side of the sewage treatment system 10, and sludge containing aerobic microorganisms is precipitated and separated from the treated water. And the to-be-processed water from which the sludge was isolate | separated is drained out of the system of the nitrogen treatment apparatus 1 as a treated water, On the other hand, the sludge separated from the to-be-processed water is the sludge extraction pipe | tube 110 from the lower part side of the sedimentation tank 22. It is pulled out through. The extracted sludge is returned to the sewage treatment system 10 through the sludge return pipe 120 at a predetermined return ratio, and the excess sludge is transferred to the concentration unit 24.

  The concentration unit 24 is configured by a processing tank or apparatus that reduces and concentrates water contained in excess sludge, and uses, for example, a concentration tank that performs gravity concentration or pressurized flotation concentration, centrifugal separation, or filtration separation. A solid-liquid separator or the like is provided. In the concentration part 24, after adding a flocculant to excess sludge and making it coagulate | solidify, a moisture content is reduced about several percent from the state of about 98-99%.

  The digestion tank 26 is a sealed tank that performs sludge decomposition treatment under anaerobic conditions. The digester 26 is provided with stirring means such as mechanical stirring for stirring excess sludge, air flow stirring, liquid flow stirring, etc., and heating means such as a boiler for heating excess sludge. In the digestion tank 26, the organic matter contained in the excess sludge is reduced in volume by the anaerobic microorganism group to reduce the volume. Thereafter, gases such as methane and carbon dioxide generated by the digestion of the organic matter are collected and used for stirring, heating, and the like, and the digested surplus sludge is transferred to the solid-liquid separation unit 28.

  The solid-liquid separation unit 28 is configured by a solid-liquid separation device that dehydrates moisture contained in excess sludge. For example, an appropriate type of solid-liquid that performs centrifugation, vacuum decompression, screw press, belt press, filter press, and the like. A separation device is provided. In the solid-liquid separation unit 28, the excess sludge is dehydrated to reduce the water content to about 70 to 90%. After that, the dehydrated cake-like sludge 27 is discharged out of the system and turned into organic material or waste. On the other hand, the sludge dehydrated filtrate (ammonia wastewater 29) generated by the dehydration process is transferred to the subaerobic tank 30.

  The sub-aerobic tank 30 is a treatment tank that performs nitrification treatment of high-concentration ammonia nitrogen wastewater using a nitrifying bacteria group and propagates AH bacteria contained in the nitrifying bacteria group. The subaerobic tank 30 is provided with aeration means for holding nitrifying bacteria and aeration of the water to be treated. The sub-aerobic tank 30 may perform either batch processing or continuous processing.

  In the sub-aerobic tank 30, the sludge dehydrated filtrate, which is high-concentration ammoniacal nitrogen wastewater, is used as water to be treated, and nitrification is performed using aerobic microorganisms containing nitrifying bacteria. The sludge dehydrated filtrate produced by the sludge solid-liquid separation is a process in which organic substances contained in the sludge are digested, and a large amount of ammonia nitrogen derived from organic nitrogen, etc., is usually produced at a higher concentration than sewage. High ammonia waste water containing ammonia nitrogen. Specifically, the ammoniacal nitrogen concentration of the sludge dehydrated filtrate is about 500 mg / L to 1000 mg / L, which is higher than the average concentration in sewage. Therefore, the ratio of AH bacteria in the ammonia oxidizing bacteria group is increased by nitrification in the sub-aerobic tank 30. In addition, since the organic matter is digested, the concentration of carbonate ions, which is the carbon source of nitrifying bacteria, is high, so that the entire nitrifying bacteria group including AH bacteria does not have to supply a carbon source from the outside. It has come to proliferate. Therefore, a large amount of nitrifying bacteria can be obtained in the auxiliary aerobic tank 30.

  The ammoniacal nitrogen concentration of the water to be treated in the sub-aerobic tank 30 is 100 mg / L or more, preferably 160 mg / L or more, more preferably 200 mg / L or more, and further preferably 400 mg / L or more. In order to adjust the ammoniacal nitrogen concentration, the sludge dehydrated filtrate may be appropriately diluted. Further, when the ammonia concentration is measured by an ammonia ion sensor or the like and the ammonia concentration is lowered, it is effective to increase the supply amount of the sludge dehydrated filtrate or reduce the aeration amount. The temperature condition of the sub-aerobic tank 30 is preferably about 30 ° C. or more and 37 ° C. or less, but the sludge dehydrated filtrate after digestion generates heat and is advantageous for the growth of nitrifying bacteria. Further, the treatment time of the nitrification treatment can be set to an appropriate time, and it is not necessary to nitrify almost the entire amount of ammonia nitrogen contained in the high concentration ammonia nitrogen waste water (29). This is because the sludge dehydrated filtrate that has been nitrified in the sub-aerobic tank 30 is then returned to the sewage treatment system 10 for processing.

  The AH bacteria grown in the secondary aerobic tank 30 are transferred to the anaerobic tank 12 of the sewage treatment system 10 together with the treated water nitrified in the secondary aerobic tank 30, and then flow out of the anaerobic tank 12. And transferred to the aerobic tank 14. And in the aerobic tank 14, the nitrification activity of AH bacteria returns under aerobic conditions, and the nitrification treatment of ammonia nitrogen contained in the sewage is performed by the aerobic microorganism group in which the transferred AH bacteria are mixed. .

  As described above, in the nitrogen treatment apparatus 1, nitrification treatment of ammonia nitrogen contained in sewage is performed using the AH bacteria grown by performing nitrification treatment of high concentration ammonia nitrogen wastewater in the sub-aerobic tank 30. Can be done. Therefore, nitrification treatment can be preferentially performed by AH bacteria when the ammonia nitrogen concentration of sewage is high, and by AL bacteria when the concentration is low. Therefore, it is possible to stably nitrify sewage whose ammonia nitrogen concentration fluctuates over a wide range and stably realize a high nitrogen removal rate. Further, when the sewage water temperature is low, the nitrification activity is maintained by the AH bacteria, so that it is possible to stably perform nitrogen removal treatment against fluctuations in the sewage water temperature.

  In the nitrogen treatment apparatus 1, AH bacteria preferentially grown in the sub-aerobic tank 30 are transferred to the anaerobic tank 12 included in the sewage treatment system 10 together with the treated water in the sub-aerobic tank 30. As a result, nitrite nitrogen and nitrate nitrogen generated by nitrification treatment in the sub-aerobic tank 30 are first subjected to denitrification treatment in the anoxic tank 12. Therefore, in the aerobic tank 14, the risk of inhibition by nitrite nitrogen is reduced, and in each treatment tank of the sub-aerobic tank 30, the anaerobic tank 12, and the aerobic tank 14, the residence time etc. The allowable range of operating conditions can be expanded.

[Nitrogen Treatment Apparatus: Second Embodiment]
Next, a nitrogen treatment apparatus according to the second embodiment of the present invention will be described.

  FIG. 2 is a configuration diagram showing an example of a nitrogen treatment apparatus according to the second embodiment of the present invention.

  As shown in FIG. 2, the nitrogen treatment apparatus 2 according to the second embodiment includes a sewage treatment system 10, a sludge treatment system 20, and a sub-aerobic tank 30, similar to the nitrogen treatment apparatus 1 described above. Yes. The nitrogen treatment apparatus 2 is different from the nitrogen treatment apparatus 1 described above in that the sewage treatment system 10 has AH bacteria preferentially grown in the sub-aerobic tank 30 together with the treated water in the sub-aerobic tank 30. It is a point directly transferred to the aerobic tank 14.

  In this nitrogen treatment apparatus 2, the AH bacteria grown in the secondary aerobic tank 30 are directly transferred to the aerobic tank 14 without being transferred to the anaerobic tank 12 of the sewage treatment system 10. In the anaerobic tank 12, which is the condition, the number and activity of AH bacteria do not decrease. Therefore, it is possible to perform the nitrification treatment of the sewage by the grown AH bacteria with high efficiency.

[Nitrogen Treatment Apparatus: Third Embodiment]
Next, a nitrogen treatment apparatus according to a third embodiment of the present invention will be described.

  FIG. 3 is a configuration diagram showing an example of a nitrogen treatment apparatus according to the third embodiment of the present invention.

  As shown in FIG. 3, the nitrogen treatment apparatus 3 according to the third embodiment includes a sewage treatment system 10 and a sludge treatment system 20. And the sewage treatment system 10 has the anoxic tank 12, the subaerobic tank 30A, and the aerobic tank 14 as a processing tank which performs biological treatment. This nitrogen treatment device 3 is characterized in that a sub-aerobic tank 30A for growing AH bacteria is incorporated in the sewage treatment system 10.

  The sub-aerobic tank 30 </ b> A is provided on the rear side of the anaerobic tank 12 and on the front side of the aerobic tank 14. The sub-aerobic tank 30A nitrifies the sludge dehydrated filtrate to proliferate AH bacteria contained in the nitrifying bacteria group, and is introduced into the sewage treatment system 10 to the treated water flowing out of the anoxic tank 12. It is a treatment tank that performs nitrification of the ammoniacal nitrogen contained. The nitrifying bacteria group may have a microorganism-immobilized form, and an appropriate type of treatment such as a fixed bed or a fluidized bed can be used.

  In the sub-aerobic tank 30A, the ammoniacal nitrogen concentration of the water to be treated is increased by the sludge dehydrated filtrate transferred from the solid-liquid separator 28. Then, the water to be treated is transferred to the aerobic tank 14 after at least a part of ammonia nitrogen is nitrified in the sub-aerobic tank 30A, and the remaining part is nitrified in the aerobic tank 14.

  The sewage treatment system 10 of the wastewater treatment apparatus 3 is provided with a bypass pipe 140 that bypasses the sub-aerobic tank 30A and allows the treated water treated in the anoxic tank 12 to flow directly into the aerobic tank 14. Yes. Usually, the treated water having a low ammonia nitrogen concentration flows into the auxiliary aerobic tank 30A from the anaerobic tank 12, which may hinder the growth of AH bacteria in the auxiliary aerobic tank 30A. . Therefore, by transferring the treated water treated in the anaerobic tank 12 directly to the aerobic tank 14 through the bypass pipe 140, the ammonia nitrogen concentration in the auxiliary aerobic tank 30A is suitable for the growth of AH bacteria. Can be maintained at different concentrations.

  About the transfer of the sewage through the bypass pipe 140, for example, the flow rate can be set based on the measurement of the ammonia nitrogen concentration of the sewage and the ammonia nitrogen concentration of the sludge dehydrated filtrate. From the above, the inflow of non-treated water into the sub-aerobic tank 30A may be blocked. Alternatively, when the sewage ammonia nitrogen concentration is high, as long as the ammonia nitrogen concentration of the sewage mixed with the sludge dehydrated filtrate in the secondary aerobic tank 30A is a concentration suitable for the growth of AH bacteria, The treated water may flow directly from the anaerobic tank 12 into the sub-aerobic tank 30A.

  In this nitrogen treatment device 3, by incorporating the sub-aerobic tank 30A into the sewage treatment system 10, it becomes possible to cause AH bacteria to perform nitrification under conditions more suitable for growth of AH bacteria, Stable nitrification treatment can be realized against fluctuations in sewage water temperature. On the other hand, in the aerobic tank 14 in the latter stage, it is possible to form an environment suitable for the growth of AL bacteria. Therefore, even if the ammoniacal nitrogen concentration fluctuates over a wide range, nitrification treatment can be performed stably with AH bacteria and AL bacteria. In addition, since the water treatment system is simplified as compared with the case where the secondary aerobic tank is provided outside the sewage treatment system 10, there is an advantage that the burden of maintenance of piping, valves, pumps, etc. is reduced. is there.

[Nitrogen Treatment Apparatus: Fourth Embodiment]
Next, a nitrogen treatment apparatus according to a fourth embodiment of the present invention will be described.

  FIG. 4 is a configuration diagram showing an example of a nitrogen treatment apparatus according to the fourth embodiment of the present invention.

  As shown in FIG. 4, the nitrogen treatment apparatus 4 according to the fourth embodiment includes a sewage treatment system 10, a sludge treatment system 20, and a sub-aerobic tank 30. And the sewage treatment system 10 has the anoxic tank 12, the subaerobic tank 30A, and the aerobic tank 14 as a processing tank which performs biological treatment. This nitrogen treatment device 4 is characterized in that a secondary aerobic tank (30, 30A) for growing AH bacteria is provided both in the sewage treatment system 10 and outside the sewage treatment system 10. doing.

  In the nitrogen treatment device 4, the sludge dehydrated filtrate (ammonia wastewater 29) generated in the solid-liquid separation unit 28 is sub-aerobic tank 30 provided outside the sewage treatment system 10 and a sub-aeration tank provided in the sewage treatment system 10. It is transferred to the aerobic tank 30A. In each of the sub-aerobic tanks 30 and 30A, nitrification treatment is performed using the sludge dehydrated filtrate as water to be treated, and AH bacteria contained in the nitrifying bacteria group are grown. The AH bacteria grown in the sub-aerobic tank 30 are transferred to the sub-aerobic tank 30A incorporated in the sewage treatment system 10 together with the water to be treated in the sub-aerobic tank 30. Thereafter, in the sub-aerobic tank 30A, at least a part of the ammonia nitrogen contained in the sewage is nitrified and then transferred to the aerobic tank 14, and the remaining part is nitrified in the aerobic tank 14.

  The sub-aerobic tank 30 provided outside the sewage treatment system 10 does not need to be subjected to substantially the entire amount of nitrification, and therefore has a smaller capacity than the sub-aerobic tank 30A provided in the sewage treatment system 10. It can be used as a tank or the residence time can be set shorter. On the other hand, the transfer of the sludge dehydrated filtrate from the solid-liquid separator 28 can be performed at an appropriate distribution ratio with respect to the sub-aerobic tank 30 and the sub-aerobic tank 30A. Therefore, when the temperature of the sewage is low and it is difficult to maintain the nitrification activity by the nitrifying bacteria group at a high level, the distribution ratio with respect to the sub-aerobic tank 30 provided outside the sewage treatment system 10 can be increased to increase ammonia. In the secondary aerobic tank 30 in which the concentration of reactive nitrogen can be easily increased, AH bacteria can be preferentially grown.

  As described above, in the nitrogen treatment apparatus 4, the auxiliary aerobic tank 30 </ b> A is provided in the sewage treatment system 10, and the auxiliary aerobic tank 30 is provided outside the sewage treatment system 10, so Since it becomes possible to carry out rapidly, it becomes easy to ensure the stability of nitrification processing. In addition, by appropriately adjusting the distribution ratio between the sub-aerobic tank 30 and the sub-aerobic tank 30A, the sewage treatment system 10 performs the nitrification process by selecting the priority of AH bacteria and AL bacteria, In the aerobic tank 30, the nitrification treatment of the nitrogen component contained in the sludge dehydrated filtrate can be sufficiently performed. Therefore, the nitrogen removal rate for the entire sewage and sludge dehydrated filtrate can be effectively increased.

[Nitrogen treatment apparatus: fifth embodiment]
Next, a nitrogen treatment apparatus according to a fifth embodiment of the present invention will be described.

  FIG. 5 is a configuration diagram showing an example of a nitrogen treatment apparatus according to the fifth embodiment of the present invention.

  As shown in FIG. 5, the nitrogen treatment apparatus 5 according to the fifth embodiment includes a sewage treatment system 10, a sludge treatment system 20, and a sub-aerobic tank 30. The sewage treatment system 10 includes an anaerobic tank 12, a first aerobic tank 14a, and a second aerobic tank 14b as treatment tanks for biological treatment. A carrier transfer pipe 160 and a carrier return pipe 170 are provided between the one aerobic tank 14a. This nitrogen treatment device 5 circulates a fluidized bed carrier in which AH bacteria are immobilized between an auxiliary aerobic tank 30 for growing AH bacteria and an aerobic tank (14a) provided in the sewage treatment system 10. It is characterized in that it is configured as described above.

  In the auxiliary aerobic tank 30 in the nitrogen treatment apparatus 5, nitrification treatment is performed using a group of nitrifying bacteria adheringly immobilized or entrapped on a fluidized bed carrier, and the proliferated AH bacteria are adheringly immobilized or entrapped. A fluidized bed carrier is obtained. In this way, AH bacteria are immobilized on the fluidized bed carrier, so that it is possible to reliably transfer the propagated AH bacteria between treatment tanks. Further, the immobilization alleviates the influence of the ammonia nitrogen concentration on the AH bacteria and suppresses the decrease in activity in the nitrification treatment of sewage with a low ammonia nitrogen concentration. In FIG. 5, treated water nitrified in the sub-aerobic tank 30 is transferred to the front side of the anaerobic tank 12 provided in the sewage treatment system 10, but the sewage treatment system 10 has. You may make it transfer directly to an aerobic tank (14a).

  A secondary aerobic tank 30 and an aerobic tank (14a) are connected to the nitrogen treatment apparatus 5, and a fluidized bed carrier on which AH bacteria are immobilized is placed between the sub-aerobic tank 30 and the aerobic tank (14a). A carrier transfer pipe 160 and a carrier return pipe 170 are provided as carrier circulation paths to be circulated. The carrier transfer pipe 160 forms a flow path through which the fluidized bed carrier flows from the sub-aerobic tank 30 between the outlet side of the sub-aerobic tank 30 and the inlet side of the first aerobic tank 14a, and the carrier return pipe 170 forms a flow path for allowing the fluidized bed carrier to flow toward the subaerobic tank 30 between the outlet side of the first aerobic tank 14a and the inlet side of the subaerobic tank 30. The carrier is repeatedly circulated while staying for a predetermined time in both the sub-aerobic tank 30 and the aerobic tank (14a).

  The carrier transfer pipe 160 and the carrier return pipe 170 are each provided with a pump or aeration means (not shown) for transferring the fluidized bed carrier. It is possible to circulate the fluidized bed carrier between the sub-aerobic tank 30 and the aerobic tank (14a) by a water flow by a pump or a water flow by a diffuser means that enables horizontal stirring such as a Kessner brush. . That is, the fluidized bed carrier in which AH bacteria are propagated in the sub-aerobic tank 30 can be transferred to the aerobic tank (14a) and sewage can be nitrified. In addition, the fluidized bed carrier whose activity has been reduced by sewage having a low ammoniacal nitrogen concentration can be returned to the subaerobic tank 30, and the AH bacteria can be re-grown in the subaerobic tank 30 and reused.

  In the nitrogen treatment apparatus 5, in FIG. 5, the sewage treatment system 10 has an aerobic tank composed of a two-stage treatment tank of a first aerobic tank 14a and a second aerobic tank 14b arranged in series. ing. In this way, the aerobic tank is configured in a plurality of stages, and the fluidized bed carrier in which AH bacteria are propagated is transferred to the foremost processing tank (first aerobic tank 14a) among the plurality of processing tanks. Accordingly, the ammoniacal nitrogen concentration in the first aerobic tank 14 a can be maintained at a high concentration in accordance with the sub-aerobic tank 30. Therefore, the activity by AH bacteria can be effectively used for sewage.

  The configuration of the sewage treatment system 10 in the nitrogen treatment device 5 is not limited to the configuration having the two-stage aerobic tanks of the first aerobic tank 14a and the second aerobic tank 14b shown in FIG. Or three or more stages may be sufficient. In addition, the carrier return pipe 170 is not a foremost processing tank (first aerobic tank 14a) among the plurality of processing tanks, but a processing tank (second aerobic tank 14b) and a sub-aerobic tank on the rear side. You may connect between 30. Further, instead of the carrier transfer pipe 160 and the carrier return pipe 170, a carrier circulation pipe having one flow path capable of changing the transfer direction of the fluidized bed carrier is provided as a sub-aerobic tank 30 and an aerobic tank (14a, 14b). It is good also as a structure which connects between these and moves a fluidized bed support | carrier in a time division manner, and reciprocates. Alternatively, an operation method may be used in which a fluidized bed carrier used in the aerobic tank (14a) of the sewage treatment system 10 is transferred to the sub-aerobic tank 30 to proliferate AH bacteria.

  As described above, in the nitrogen treatment device 5, the fluidized bed carrier in which AH bacteria are immobilized is circulated between the sub-aerobic tank 30 and the aerobic tank provided in the sewage treatment system 10. The number of AH bacteria grown in the sub-aerobic tank 30 can be easily maintained. Moreover, since the nitrification activity of AH bacteria can be used immediately for sewage, the stability of nitrification is further improved against the increase in ammonia nitrogen concentration and the decrease in water temperature. This is advantageous.

  In addition, the structure of the nitrogen treatment apparatus according to each of the above embodiments may be combined with each other or replaced. For example, the nitrogen treatment apparatus according to the first embodiment to the fourth embodiment may be provided with a carrier circulation path, or the treatment tank configuration of the sewage treatment system of the nitrogen treatment apparatus according to the first embodiment to the fifth embodiment. You may change and apply. Further, another processing unit may be added to the sludge processing system 20, and the concentration unit 24 and the like may be omitted.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples of the present invention, but the present invention is not limited thereto.

[Example 1]
As Example 1, the nitrogen treatment method according to the above embodiment was applied, and a treatment test using low-temperature wastewater as treated water using AH bacteria grown by performing nitrification treatment of high-concentration ammoniacal nitrogen wastewater. went.

  In the treatment test, an inorganic synthetic wastewater mainly composed of ammonium sulfate and sodium carbonate was used as high concentration ammoniacal nitrogen wastewater. Further, as the water to be treated, sewage having a low ammoniacal nitrogen concentration was assumed, and the ammoniaum ion concentration of the inorganic synthetic wastewater was diluted stepwise and used in a simulated manner. The water temperature of the water to be treated was set to 7 ° C. assuming a low water temperature treatment. In addition, the tank capacity of the treatment tank used for the treatment test was 2.0 L, and the treatment tank was filled with 10% of a fluidized bed carrier in which aerobic bacteria group (activated sludge) including nitrifying bacteria group was comprehensively immobilized. .

  In the treatment test, nitrification treatment of high concentration ammonia nitrogen wastewater with ammonia nitrogen concentration set at 330 mg / L was performed for 70 days by the nitrifying bacteria group, and AH bacteria contained in the nitrifying bacteria group were grown. After that, wastewater whose ammonia nitrogen concentration was lowered to 100 mg / L, 40 mg / L, 20 mg / L in stages was introduced into the treatment tank, and continuous treatment was carried out, before and after nitrification treatment. Each nitrogen concentration (concentration of each nitrogen component) was continuously measured.

  FIG. 6 is a diagram illustrating the nitrogen concentration of the water to be treated to which the wastewater treatment method according to the example is applied. Moreover, FIG. 7 is a figure which expands partially and shows the change of the nitrogen concentration of the to-be-treated water to which the wastewater treatment method according to the embodiment is applied.

  6 and 7, the horizontal axis represents the time (days) after the start of the treatment test, and the vertical axis represents the nitrogen concentration (mg / L) contained in the water to be treated. ◯ is the ammonia nitrogen concentration in the treated water (raw water) before nitrification, ● is the ammonia nitrogen concentration in the treated water (treated water) after nitrification, and ■ is the treated water after nitrification Nitrite nitrogen concentration in water (treated water), and ▲ indicate nitrate nitrogen concentration in treated water (treated water) after nitrification. FIG. 7 shows an extracted section from 115 days to 140 days in FIG.

  As shown in FIGS. 6 and 7, in the nitrification treatment using the grown AH bacteria, the nitrification activity is maintained at a high level even though the water temperature of the treated water is as low as 7 ° C. I understand. Compared to the ammoniacal nitrogen concentration of the treated water before nitrification, the ammoniacal nitrogen concentration of the treated water after nitrification is greatly reduced, and nitrite nitrogen and nitrate nitrogen are sufficiently generated. .

  As a result of continuing the continuous treatment of Example 1, as shown in FIG. 7, at the stage where the ammoniacal nitrogen concentration was reduced to 20 mg / L (average ammonia concentration of 21 mg / L), the treatment after nitrification treatment Water has an average ammoniacal nitrogen concentration of 1.6 mg / L.

[Comparative Example 1]
As Comparative Example 1, a nitrification treatment of high-concentration ammoniacal nitrogen wastewater was not performed, and a treatment test was performed using low-temperature wastewater as treated water using a normal nitrifying bacteria group in which AH bacteria were not grown.

  The treatment test was carried out in the same manner as in Example 1 except that the water to be treated with the ammoniacal nitrogen concentration set to a constant concentration of 20 mg / L was continuously treated. As a result, the treated water after nitrification remained at an average nitrogenous nitrogen concentration of 9.8 mg / L. In addition, when sludge was collected from the vicinity of the treated water and the outlet of the treatment tank and a nitrification test of waste water with a water temperature of 7 ° C. was performed, the nitrification rate (consumption rate of ammonia nitrogen) was the same as in Example 1. In comparison with the above, only about 1/5 times the speed was observed.

[Example 2]
As Example 2, the nitrogen treatment method according to the above embodiment was applied, and a treatment test using low temperature sewage as treated water was performed using a test system simulating the nitrogen treatment apparatus according to the first embodiment.

  In the treatment test, a nitrogen treatment apparatus was used in which a precipitation tank was installed after the simulated sewage treatment system having an oxygen-free tank and an aerobic tank, and a separate aerobic tank was provided independently. The tank capacity of each treatment tank was an anaerobic tank 5.0 L, an aerobic tank 4.0 L, a precipitation tank 2.0 L, and a sub-aerobic tank 2.0 L.

  First, while using simulated sewage treatment system, simulated sewage with low water temperature and low ammonia nitrogen concentration as treated water, while returning sludge at a flow rate equal to the inflow rate of treated water from the settling tank to the oxygen-free tank, The nitrification liquid was returned from the aerobic tank to the anoxic tank at a flow rate three times the inflow rate of the water to be treated, and the system was operated under the SS concentration (floating substance concentration) of 2000 mg / L. Specifically, the water to be treated is mainly composed of ammonium sulfate and sodium acetate, the ammonia nitrogen concentration is 40 mg / L, the C / N ratio is 2.5, and the water temperature is 14 ° C. Some simulated sewage was used.

  As a result of operating the treated water by operating only the simulated sewage treatment system, the ammonia nitrogen concentration of the treated water remained at an average value of about 5 mg / L. At this time, it was recognized that the ammoniacal nitrogen concentration of the treated water fluctuated with time and the nitrification treatment could become unstable.

  Subsequently, the subaerobic tank was filled with 10% of a fluidized bed carrier in which the sludge dehydrated filtrate was used as high-concentration ammoniacal nitrogen wastewater and the aerobic bacteria group (activated sludge) including the nitrifying bacteria group was comprehensively immobilized. Drove. In addition, as high concentration ammonia nitrogen wastewater, the sludge dehydration filtrate extract | collected from the sewage treatment plant was adjusted and used for ammonia nitrogen concentration 900 mg / L. The water temperature of the high-concentration ammonia nitrogen wastewater was 30 ° C.

  As a result of operating only the subaerobic tank and nitrifying high-concentration ammoniacal nitrogen wastewater, approximately 50% of ammoniacal nitrogen was nitrified. Thereafter, sludge was periodically collected from the vicinity of the outlet of the secondary aerobic tank and from the piping, and was put into a simulated sewage treatment system for nitrification treatment of the water to be treated. As a result, the ammoniacal nitrogen concentration of the treated water reached 1 mg / L or less.

  From the above results, by growing AH bacteria contained in the nitrifying bacteria group in high concentration ammonia nitrogen wastewater and using the AH bacteria for nitrification treatment of the water to be treated, It can be seen that the nitrogen removal treatment can be performed stably even if the water temperature decreases with the increase. Moreover, even if the ammoniacal nitrogen concentration of to-be-processed water falls, the activity of the proliferated AH microbe is maintained, and it turns out that the proliferated AH microbe can be utilized continuously. .

DESCRIPTION OF SYMBOLS 1 Nitrogen treatment apparatus 10 Sewage treatment system 12 Anoxic tank 14 Aerobic tank 20 Sludge treatment system 22 Precipitation tank 24 Concentration part 26 Digestion tank 28 Solid-liquid separation part 27 Sludge 29 Ammonia waste water (high concentration ammonia nitrogen waste water)
30 Subaerobic tank 100 Nitrification liquid return pipe 110 Sludge extraction pipe 120 Sludge return pipe

Claims (9)

A nitrogen treatment method for biologically removing nitrogen components contained in waste water,
Nitrification bacteria are used to nitrify high-concentration ammonia nitrogen wastewater containing ammonia nitrogen at a higher concentration than the wastewater, and the high-concentration ammonia-resistant bacteria (AH bacteria) contained in the nitrification bacteria group are propagated. Process,
Performing the nitrification treatment of the wastewater using the proliferated AH bacteria;
And a step of denitrifying the wastewater that has been subjected to the nitrification treatment. The high-concentration ammoniacal nitrogen wastewater is a sludge dehydrated filtrate produced by dehydration after anaerobic digestion of excess sludge generated by nitrification of the wastewater,
The nitrogen treatment method according to claim 1, wherein the sludge dehydrated filtrate has an ammoniacal nitrogen concentration of 100 mg / L or more. The waste water is sewage,
The nitrogen treatment method according to claim 1 or 2, wherein the ammonia nitrogen concentration of the sewage is less than 100 mg / L.   The nitrogen treatment method according to any one of claims 1 to 3, wherein the temperature of the wastewater subjected to nitrification is 20 ° C or lower. A nitrogen treatment apparatus for biologically removing nitrogen components contained in waste water,
An aerobic tank for nitrifying the wastewater;
An oxygen-free tank for performing denitrification treatment of the wastewater subjected to the nitrification treatment,
Nitrification bacteria are used to nitrify high-concentration ammonia nitrogen wastewater containing ammonia nitrogen at a higher concentration than the wastewater, and the high-concentration ammonia-resistant bacteria (AH bacteria) contained in the nitrification bacteria group are propagated. With a secondary aerobic tank,
A nitrogen treatment apparatus that performs nitrification treatment of the wastewater using the proliferated AH bacteria. The high-concentration ammoniacal nitrogen wastewater is a sludge dehydrated filtrate produced by dehydration after anaerobic digestion of excess sludge generated by nitrification of the wastewater,
The nitrogen treatment apparatus according to claim 5, wherein the sludge dehydrated filtrate has an ammoniacal nitrogen concentration of 100 mg / L or more. The waste water is sewage,
The nitrogen treatment apparatus according to claim 5 or 6, wherein the ammonia nitrogen concentration of the sewage is less than 100 mg / L. The aerobic tank comprises a plurality of processing tanks,
The nitrogen treatment apparatus according to any one of claims 5 to 7, wherein the proliferated AH bacteria are transferred to a foremost treatment tank among the plurality of treatment tanks.   A carrier circulation path for connecting the sub-aerobic tank and the aerobic tank and circulating the fluidized bed carrier on which the AH bacteria are immobilized between the sub-aerobic tank and the aerobic tank; The nitrogen treatment apparatus according to any one of claims 5 to 8, wherein the nitrogen treatment apparatus is characterized.

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