JP6414394B2 - Method for treating ammonia nitrogen-containing water - Google Patents

Description

  The present invention relates to a method for treating ammonia nitrogen-containing water.

Groundwater, river water, lake water, etc. often contain about several mg / L of ammonia nitrogen. In particular, groundwater often contains about 0.1 to 3 mg / L of ammonia nitrogen, and sometimes the concentration of ammonia nitrogen exceeds 10 mg / L.
When drinking water containing nitrogen, it is necessary to meet water quality standards based on the Water Supply Law. Specifically, among the total nitrogen contained in water, “nitrate nitrogen and nitrite nitrogen” is 10 mg / L or less, and “nitrite nitrogen” is 0.04 mg / L or less (from April 1, 2014 Add). Water quality standards are not established for “ammonia nitrogen”. However, if ammonia nitrogen is present in water, sodium hypochlorite added for disinfection reacts with ammonia nitrogen and is consumed. In this case, an excess of sodium hypochlorite equivalent to about 10 times the amount of ammonia nitrogen is required, resulting in a significant increase in running cost. Therefore, when drinking water containing ammonia nitrogen, it is necessary to sufficiently reduce the ammonia nitrogen concentration before disinfection with sodium hypochlorite.

As a method for removing ammonia nitrogen contained in water when drinking groundwater or the like, for example, a method using an ion exchange method or a discontinuous point alkali chlorine method is known. Specifically, for example, a method using the processing apparatus 200 illustrated in FIG.
In the method using the processing apparatus 200, first, groundwater is pumped from the well by the well pump 210 and sent to the sand filtration tower 212, and filtration is performed as a pretreatment. Thereby, in the ion exchange tower 214 of the next process, it is suppressed that a malfunction arises with sand, clay, etc. Next, ground water is sent to the ion exchange tower 214 filled with the ion exchange resin, treated by an ion exchange method to remove part of the ammonia nitrogen, and the treated water is temporarily stored in the intermediate tank 216. Thereafter, the treated water is pumped out from the intermediate tank 216 by the treatment pump 218, sodium hypochlorite is added and the remaining ammonia nitrogen is removed by the discontinuous point alkali chlorine method, and then sent to the sand filtration tower 220 for filtration treatment. I do. Thereafter, the treated water is sent to the activated carbon tower 222 to remove the remaining sodium hypochlorite by bringing it into contact with the activated carbon, adding sodium hypochlorite for disinfection, and filtering by the UF membrane filtration device 224 for treatment. The liquid is stored in the water tank 226. For the treated water after filtration by the UF membrane filtration device 224, the residual chlorine concentration is monitored by measurement with the residual chlorine meter 230. The treated water stored in the treated water tank 226 is sent to a predetermined place by the treatment pump 228.

  However, the ion exchange method has disadvantages such as an expensive apparatus (ion exchange column), a large consumption of salt used as an ion exchange medium, and a high running cost. Also, the discontinuous point alkali chlorine method requires the addition of about 10 times the equivalent amount of sodium hypochlorite with respect to the ammonia nitrogen, so that the running cost becomes high. For this reason, it is expensive to use the conventional treatment method for drinking groundwater.

On the other hand, a nitrification denitrification method using nitrifying bacteria and denitrifying bacteria has been proposed as a biological treatment method for industrial wastewater containing ammonia nitrogen (Patent Documents 1 and 2).
However, in the nitrification denitrification method using nitrifying bacteria and denitrifying bacteria, it is difficult to control the reaction conditions because there are two reaction systems of nitrification under aerobic conditions and denitrification under anaerobic conditions. The removal rate of ammonia nitrogen tends to be unstable. When the removal rate of ammonia nitrogen becomes unstable, it becomes difficult to control the amount of addition when disinfecting sodium hypochlorite is added later. In order to stabilize the removal rate of ammonia nitrogen in the nitrification denitrification method, a large apparatus and a complicated control mechanism are required, and the cost increases.

Further, in the nitrification / denitrification method using nitrification bacteria and denitrification bacteria, organic substances (BOD) of about 2 to 3 times the amount of nitrogen are generally required as a hydrogen donor in the denitrification reaction. However, in groundwater and the like, the content of organic substances serving as hydrogen donors is small, and in most cases, it is less than the necessary amount for denitrification reaction.
In denitrification for industrial wastewater treatment, methanol is generally added as a hydrogen donor. However, since methanol is not suitable for drinking, when processing water is used as drinking water, advanced treatment facilities such as a re-aeration tank and an activated carbon tower are required to remove residual methanol, which increases costs. Although it is conceivable to use ethanol as a hydrogen donor, ethanol is more expensive than methanol. Also in this case, an advanced treatment facility for removing residual ethanol is required. In addition, a method using hydrogen gas as a hydrogen donor is difficult to put into practical use because of concerns such as explosion.
In addition, groundwater, river water, lake water, etc. may contain methane and hydrogen sulfide. Therefore, it is important that the ammonia nitrogen concentration can be stably reduced even if these components are contained.

Japanese Patent Laid-Open No. 9-1184 JP 2001-299137 A

  The present invention provides a method for treating ammonia nitrogen-containing water that can stably reduce the ammonia nitrogen concentration of ammonia nitrogen-containing water containing either or both of methane and hydrogen sulfide and ammonia nitrogen at low cost. For the purpose.

The method for treating ammonia-nitrogen-containing water of the present invention adheres to a microorganism carrier without using a nitrification denitrification method for ammonia-nitrogen-containing water containing one or both of methane and hydrogen sulfide and ammonia nitrogen. A nitrification treatment is carried out by a catalytic oxidation method using the nitrifying bacteria, and aeration is performed at an aeration intensity of 2 to 10 m ³ / m ³ · hr during the nitrification treatment.

In the method for treating ammonia-nitrogen-containing water according to the present invention, the microorganism carrier has a tree-like structure in which branches are branched from a trunk, and is formed of a string-like body in which the diameter of the trunk is different from the diameter of the branches. A string-like carrier is preferable.
Further, the nitrification treatment is performed so that a plurality of the string-shaped carriers are arranged so that the axial direction of the trunk portion is a vertical direction, and the tip portions of the branch portions of adjacent string-shaped carriers overlap in a plan view. It is preferable to arrange in a nitrification tank for performing the above.
In addition, it is preferable that the entire nitrification tank in which the nitrification treatment is performed is aerated.
In addition, while supplying the ammonia nitrogen-containing water to the nitrification tank for performing the nitrification treatment, a continuous nitrification treatment in which the treated water is extracted from the nitrification tank, and the residence time of the ammonia nitrogen-containing water in the nitrification tank ( HRT) is preferably 0.5 to 2 hours.
Moreover, it is preferable to perform the nitrification treatment without performing an aeration treatment as a pretreatment for the ammonia nitrogen-containing water.

  According to the method for treating ammonia nitrogen-containing water of the present invention, the ammonia nitrogen concentration of ammonia nitrogen-containing water containing either or both of methane and hydrogen sulfide and ammonia nitrogen can be stably reduced at low cost. .

It is the perspective view which showed the string-shaped carrier which is an example of a microorganisms carrier. It is sectional drawing (a) which cut | disconnected the string-shaped support body of FIG. 1 in the direction perpendicular | vertical to the axial direction of a trunk, and the side view (b) of the string-shaped support body of FIG. It is the schematic diagram which showed an example of the processing apparatus of ammonia nitrogen containing water used for the processing method of this invention. It is the schematic diagram which showed an example of the processing apparatus of the conventional ammonia nitrogen containing water. FIG. 3 is a schematic diagram showing a processing apparatus used in Example 1. 6 is a schematic diagram showing a processing apparatus used in Example 2. FIG. 5 is a graph showing the relationship of the nitrification rate with respect to the treatment period in Example 1 and Example 2. 10 is a schematic diagram showing a processing apparatus used in Example 6. FIG. It is the graph which showed the relationship between the water temperature with respect to the process period in Example 6 and Example 7, and a nitrification rate. 10 is a graph showing the relationship between ammonia nitrogen concentration and nitrification rate with respect to the treatment period in Example 8. 10 is a graph showing the relationship of ammonia nitrogen concentration to elapsed days in Example 10.

  In the method for treating ammonia nitrogen-containing water according to the present invention, the microbial carrier is used without using nitrification denitrification for ammonia nitrogen-containing water containing either or both of methane and hydrogen sulfide and ammonia nitrogen. Nitrification is performed by contact oxidation using the attached nitrifying bacteria. Nitrogen in water is nitrated to nitrate nitrogen or nitrite nitrogen by nitrification by contact oxidation, that is, treatment under aerobic conditions using nitrification by nitrifying bacteria attached to the microorganism carrier. The ammonia nitrogen concentration is reduced.

Examples of ammonia nitrogen-containing water to be treated by the present invention include ground water, river water, lake water, and the like.
For example, compared to sewage and industrial wastewater with ammonia nitrogen concentration of tens to hundreds of mg / L, groundwater has a low ammonia nitrogen concentration of 15 mg / L or less, but it is used by attaching nitrifying bacteria to the microorganism carrier. Thus, even when water having a low ammonia nitrogen concentration is treated, nitrifying bacteria are likely to grow, and the treatment efficiency (nitrification rate) is increased.

In the treatment method of the present invention, aeration is performed at an aeration intensity of 2 to 10 m ³ / m ³ · hr during the nitrification treatment. As a result of intensive studies by the present inventors, it has been found that when one or both of methane and hydrogen sulfide are contained in the ammonia nitrogen-containing water, the nitrification rate of ammonia nitrogen by nitrifying bacteria decreases. As a result of further investigation, by aeration with an aeration intensity of 2 to 10 m ³ / m ³ · hr during nitrification treatment, methane and hydrogen sulfide contained in ammonia nitrogen-containing water are diffused into the gas phase and stable. It was found that a high nitrification rate can be obtained.

Aeration intensity is 2~10m ³ / ^{m 3} · ^hr, preferably ^{3~7m 3 / m 3 · hr,} 4~5m 3 / m 3 · hr is, taking into account the power of the blower supplying air More preferable. If the aeration intensity is equal to or higher than the lower limit, the removal efficiency of methane and hydrogen sulfide in ammonia nitrogen-containing water becomes high, and a high nitrification rate can be obtained stably. If aeration intensity is below the said upper limit, it can suppress that nitrifying bacteria fall off from a microorganism support body.
Note that the aeration intensity ^{(m 3 / m 3 · hr} ), means the aeration per hour to the effective volume of the nitrification reactor.

As the aeration method during the nitrification treatment, full-surface aeration is preferable. By adopting full-surface aeration, methane and hydrogen sulfide contained in ammonia nitrogen-containing water can be easily and efficiently diffused into the gas phase, and a higher nitrification rate can be stably obtained. The entire surface aeration can be performed, for example, by disposing a diffuser tube over the entire bottom of the nitrification tank and generating an upward flow by bubbles generated from the diffuser tube.
In the treatment method of the present invention, for example, the microorganism carrier and the air diffuser are partitioned by a partition plate or the like installed in the vertical direction in the nitrification tank, and the water flow generated along with the bubbles generated from the air diffuser is separated from the partition plate. Alternatively, partial aeration may be employed that reaches the microorganism carrier from above and returns to the aeration tube side from below the partition plate to cause a swirling flow.

The water temperature of the ammonia nitrogen-containing water during nitrification is preferably 9 to 25 ° C. If the water temperature is in the above range, the same nitrification effect can be obtained, and the ammonia nitrogen concentration can be sufficiently reduced.
In addition, when groundwater, river water, lake water, etc. are nitrified using inoculum obtained by acclimating nitrifying bacteria in advance for a predetermined period of time at a water temperature of 10 to 16 ° C., the water temperature is stable and high even if the water temperature is low. Since the nitrification rate is obtained, it is not necessary to adjust the water temperature during the treatment. In this case, since the temperature control equipment is not necessary, the equipment cost is lowered.

  The nitrification treatment by the catalytic oxidation method of ammonia nitrogen-containing water may be performed batchwise or continuously. Batch-type nitrification treatment is a treatment in which ammonia nitrogen-containing water is supplied to a nitrification tank, then nitrification treatment is performed while aeration is performed, and then the treatment water is extracted from the nitrification tank. The continuous nitrification treatment is a treatment in which ammonia nitrogen-containing water is supplied to the nitrification tank and the nitrification treatment is continuously performed while extracting the treatment water from the nitrification tank.

In the treatment method of the present invention, it is preferable to employ a continuous nitrification treatment from the viewpoint of efficiently treating more ammonia nitrogen-containing water.
When the nitrification treatment is performed continuously, the residence time (HRT) of the ammonia nitrogen-containing water in the nitrification tank provided with the microorganism carrier to which nitrifying bacteria are attached is preferably 0.5 to 2 hours, 1.0 to 1.5 hours is more preferable in consideration of processing stability and economy. When the residence time (HRT) is equal to or greater than the lower limit, a high nitrification rate can be easily obtained, and the ammonia nitrogen concentration can be sufficiently reduced. If the residence time (HRT) is less than or equal to the above upper limit value, the nitrification tank can be further miniaturized, and the equipment cost can be reduced.

In the treatment method of the present invention, it is preferable to perform nitrification treatment on the ammonia nitrogen-containing water without performing aeration treatment as a pretreatment. By not performing the aeration treatment as the pretreatment, it is not necessary to provide an aeration tank in the previous stage of the nitrification tank, which is advantageous in terms of cost.
In addition, if it is a range which does not impair the effect of this invention, you may perform an aeration process as pre-processing with respect to ammonia nitrogen containing water.

(Microorganism carrier)
As a microorganism-supporting body, a string having a tree-like structure in which a branch portion branches from a trunk portion and a diameter of the trunk portion and a diameter of the branch portion are different from the point that a high nitrification rate can be stably obtained. The carrier is preferably a string carrier (hereinafter referred to as string carrier X). When the branch portion is composed of a plurality of yarns, the diameter of the branch portion means the diameter of a circumscribed circle that is in contact with the outer surface of the yarns when the plurality of yarns are bundled.
In the string-shaped carrier X, sufficiently large voids are formed between the branch portions so that the ammonia nitrogen-containing water and bubbles generated by aeration can pass smoothly. In addition, the residence time of the bubbles between the branches of the string-like carrier X can be made sufficiently long, and the bubbles can be refined (cut) to improve the oxygen dissolution efficiency and the removal rate of methane and hydrogen sulfide. Can be planned. Moreover, the string-like carrier X has a larger surface area than other microorganism carriers, and can attach more nitrifying bacteria. From these things, a higher nitrification rate can be realized by using the string-shaped carrier X.

Surface area per length 1m cord-like carrier X is preferably at least ^2m 2 / m, more preferably at least ^3m 2 / m, still more preferably at least 4.5 m ² / m. If the surface area is equal to or greater than the lower limit, more nitrifying bacteria can be attached, and a high nitrification rate is easily obtained.

Specific examples of the string-shaped carrier X include, for example, the string-shaped carrier 10 illustrated in FIGS. 1 and 2. The string-like carrier 10 is a string-like body having a tree structure having a trunk portion 12 and an annular branch portion 14 branched from the trunk portion 12.
The diameter of the annular branch portion 14 is smaller than the diameter of the trunk portion 12. Since the passage speed of the bubbles in the string-like carrier 10 is suppressed by the large-diameter trunk portion 12, the residence time of the bubbles in the string-like carrier 10 becomes longer. Further, the bubbles passing through the string-like carrier 10 are cut by the small-diameter annular branch portion 14 to be miniaturized. By the action of these large-diameter trunk 12 and small-diameter annular branch 14, the oxygen dissolution efficiency is increased, and the partial pressure of methane and hydrogen sulfide is reduced by increasing the oxygen (air) partial pressure in the liquid. Since the emission is accelerated and the removal rate of methane and hydrogen sulfide is improved, a high nitrification rate is easily obtained.

The trunk 12 in this example has a braid structure. Since the trunk portion 12 has a braided structure, an action of meandering the passage route of the bubbles in the string-like carrier 10 is obtained, and the residence time of the bubbles becomes longer.
The diameter of the trunk portion 12 is preferably 3 to 10 mm, and more preferably 5 to 7 mm. If the diameter of the trunk portion 12 is equal to or greater than the lower limit value, the bubble residence time in the string carrier 10 becomes longer. If the diameter of the trunk portion 12 is less than or equal to the above upper limit value, the trunk portion 12 is appropriately rocked, and the annular branch portion 14 is also rocked accordingly, thereby facilitating the biological reaction.

The annular branch portion 14 is formed by each of a clockwise thread and a counterclockwise thread constituting the braid structure of the trunk section 12. By forming the annular branch portion 14 by each of the clockwise thread and the counterclockwise thread constituting the braid structure of the trunk portion 12, an effect of miniaturizing the bubbles is easily obtained.
Such an annular branch portion 14 can be integrally formed in a series of steps when the braid structure of the trunk portion 12 is formed.

Further, in this example, the braid structure of the trunk portion 12 is composed of two thick yarns and four thin yarns, and the annular branch portion 14 is formed by a thick yarn of the two types of yarns. 14A and the annular branch part 14B formed with a thin thread are mixed.
When the annular branch portion 14A formed of a thick thread and the annular branch portion 14B formed of a thin thread are mixed, it is easy to suppress the bulk density per unit length of the string-like carrier 10 from becoming too large. . Further, the annular branch portion 14A formed of a thick thread has a high effect of meandering the passage path of bubbles, and the annular branch portion 14B formed of a thin thread has a high effect of miniaturizing the bubbles. Therefore, the presence of these makes it easy to obtain the effect of increasing the oxygen dissolution efficiency and the removal rate of methane and hydrogen sulfide by making the bubbles fine while extending the residence time of the bubbles.
The diameter of the thick thread forming the annular branch portion 14A is preferably 2 to 4 mm. The diameter of the thin thread forming the annular branch portion 14B is preferably 0.2 to 0.5 mm.

The yarn forming the trunk portion 12 and the annular branch portion 14 can be formed by binding a plurality of filament yarns.
Examples of the material of the filament yarn that forms a thick yarn include polypropylene, metals, polyethylene, polyurethane, polyester, polystyrene, vinyl chloride, fluororesin, polycarbonate, polyacetal, and ABS. If a filament yarn made of a material having a specific gravity lighter than water, such as propylene, is used for the thick yarn, the tip of the annular branch portion 14A is unlikely to hang down in water, and the annular branch portion 14 tends to have a sufficiently widened shape. Thereby, the effect by the annular branch part 14 becomes easier to be obtained.
Examples of the material of the filament yarn that forms the thin yarn include vinylon, polypropylene, and nylon.
The diameter of the filament yarn is preferably 10 to 50 μm.

The annular branch portion 14 preferably includes a yarn in which a plurality of filament yarns are bundled and processed to be bulky. In particular, it is preferable that the annular branch portion 14A formed of a thick yarn includes a yarn in which a plurality of filament yarns are bundled and processed to be bulky. Thereby, it becomes easy to obtain the effect of meandering the passage route of the bubbles in the string-like carrier 10 and the effect of miniaturizing the bubbles.
Specific examples of high-bulk processed yarns include yarns that are bundled by Taslan processing so that a plurality of floats are entangled with the core yarn, or a plurality of floats that do not have a core yarn are subjected to bulking (suspension processing). For example, yarns that are bound by shrinking).

The diameter of the annular branch portion 14A is preferably 1 to 5 mm, and more preferably 2 to 4 mm. If the diameter of the annular branch portion 14A is equal to or greater than the lower limit value, an effect of meandering the passage route of bubbles is easily obtained. If the diameter of the annular branch portion 14A is equal to or less than the upper limit value, it is easy to obtain the effect of miniaturizing the bubbles.
The diameter of the annular branch portion 14B is preferably 0.1 to 0.7 mm, and more preferably 0.2 to 0.4 mm. If the diameter of the annular branch portion 14B is equal to or greater than the lower limit value, the effect of meandering the passage route of bubbles is easily obtained. If the diameter of the annular branch portion 14B is equal to or less than the upper limit value, it is easy to obtain the effect of miniaturizing the bubbles.

The annular branch portions 14 </ b> A made of thick yarns and the annular branch portions 14 </ b> B made of thin yarns are alternately arranged with an interval in the axial direction of the trunk portion 12. The pitch between the annular branch portion 14A and the annular branch portion 14B is preferably constant. In addition, you may change the pitch of 14 A of annular branch parts, and the annular branch part 14B as needed.
In this example, the pitch of the annular branch portions 14A adjacent to each other in the axial direction of the trunk portion 12 is 7 to 10 mm, and the annular branch portions 14B are arranged with an appropriate interval therebetween.

As shown in FIG. 2B, the annular branch portions 14 are formed to project in pairs in a direction perpendicular to the axial direction of the trunk portion 12. Thereby, it is easy to obtain the effect of meandering the passage route of bubbles and the effect of refining the bubbles by the respective annular branches 14.
Further, in the string-like carrier 10, the trunk portion 12 is twisted, so that the plurality of annular branch portions 14 are spirally arranged in the axial direction of the trunk portion 12. Thereby, since the annular branch part 14 is arrange | positioned toward the various directions centering | focusing on the trunk | trunk part 12 by planar view, it becomes easy to catch the bubble which passes the string-shaped carrier 10 without remaining. Therefore, the effect of meandering the bubble passage path and the effect of miniaturization can be more stably exhibited.
The twist of the trunk portion 12 can be imparted when forming the braid structure.

The shape of the annular branch portion 14 is in the form of a water drop, that is, an annular shape with the width gradually increasing toward the outside in the direction perpendicular to the axial direction of the trunk portion 12 and the tip end being narrowed.
The width d (FIG. 2A) of the annular branch portion 14 at an intermediate position in the direction perpendicular to the axial direction of the trunk portion 12 is preferably about 1 to 2 mm.

The structure of the trunk part and the branch part of the string-like carrier X is not limited to the structure of the trunk part 12 and the annular branch part 14 described above. For example, the branch part does not need to be annular. Moreover, the branch part which is not cyclic | annular and the cyclic | annular branch part may be mixed. In terms of high effect of increasing the oxygen dissolution efficiency and the removal rate of methane and hydrogen sulfide by refining the bubbles, the branch part preferably includes a cyclic branch part, and more preferably is a cyclic branch part.
Moreover, the string-like carrier X in which the diameter of the trunk is thinner than the diameter of the branch may be used.

What is necessary is just to set suitably the length of the string-shaped support body 10, ie, the length of the axial direction of the trunk | drum 12, according to the apparatus to be used, for example, can be made into several dozen m-several hundred m.
What is necessary is just to set suitably the diameter of the string-shaped support body 10, ie, the diameter of the circumscribed circle in contact with the front-end | tip of the annular branch part 14 in planar view, for example, can be set to about 100 mm. The diameter of the string-like carrier 10 can be adjusted by adjusting the diameter of the trunk portion 12 and the length of the annular branch portion 14 in the direction perpendicular to the axial direction of the trunk portion 12.

  When installing a plurality of string-like carriers X in a nitrification tank for performing nitrification treatment, the branch portions of adjacent string-like carriers X so that the axial direction of the trunk portion of each string-like carrier X is a vertical direction It is preferable to install so that the front-end | tip parts may overlap in planar view. The smaller the bubble diameter of bubbles generated by aeration, the higher the efficiency of methane and hydrogen sulfide being diffused into the gas phase. By installing the adjacent string-shaped carriers X as described above, the amount of bubbles passing between the adjacent string-shaped carriers X without being miniaturized can be reduced. For this reason, bubbles supplied by aeration can be sufficiently refined by the string-shaped carrier X in the nitrification tank, and methane and hydrogen sulfide are more efficiently diffused into the gas phase, thereby stabilizing the high nitrification rate. It becomes easy to obtain.

When the adjacent string-shaped carriers X are installed so that the end portions of the branch portions overlap in plan view, the pitch of the adjacent string-shaped carriers X (the distance between the trunk and the trunk) is two string-shaped carriers in water. 0.8 to 0.9 times is preferable and 0.8 to 0.85 times is more preferable with respect to the distance between the trunks when the branch ends of the body X are in contact with each other. If the pitch is equal to or greater than the lower limit value, the amount of gas passing between adjacent string-shaped carriers X without being refined can be reduced. If the pitch is less than or equal to the upper limit value, methane and hydrogen sulfide in ammonia nitrogen-containing water are easily diffused into the gas phase, and a high nitrification rate is easily obtained.
In the present invention, the string-like carrier X may be installed in the nitrification tank so that the axial direction of the trunk portion is the horizontal direction.

  As the microorganism carrier, a carrier other than the above-described string-like carrier X may be used. For example, a string-like carrier other than the string-like carrier X, a granular carrier (ceramic, activated carbon, etc.), a net-like carrier (golf net, fishing net, etc.), etc. may be used.

(Nitrifying bacteria)
As nitrifying bacteria, known nitrifying bacteria used for nitrification treatment of ammonia nitrogen can be used. Among them, nitrifying bacteria are obtained by acclimating nitrifying bacteria at a water temperature of 10 to 16 ° C. in advance for a predetermined period from the point that a high nitrification rate can be stably obtained even if the temperature of ammonia nitrogen-containing water during treatment is low. It is preferable to use an inoculum (hereinafter also referred to as inoculum Y).
As for the water temperature at the time of acclimatization which obtains inoculum Y, 13-15 ° C is more preferred.

Nitrifying bacteria usually do not grow as the water temperature is lower, and the nitrifying activity is lower. However, as a result of intensive studies by the present inventors, when the nitrifying bacteria are acclimatized at a water temperature of 10 to 16 ° C. for a predetermined period (for example, about 40 days), the activity of the nitrifying bacteria rapidly increases, and at an appropriate temperature (for example, 25 ° C.). It was found that nitrification activity equivalent to nitrification activity was obtained. What is necessary is just to set suitably the period which acclimatizes nitrifying bacteria at the water temperature of 10-16 degreeC according to conditions other than water temperature.
Such an inoculum Y can acquire nitrification activity equivalent to nitrification activity at an appropriate temperature (for example, 25 ° C.) in a short period of time even at around 10 ° C. Therefore, by using inoculum Y, when groundwater, river water, lake water, etc. are nitrified, a stable high nitrification rate can be obtained even if the water temperature fluctuates depending on the morning and evening, so the temperature of the water temperature during treatment Preparation equipment is no longer required.

When acclimatizing the nitrifying bacteria at a water temperature of 10 to 16 ° C. for a predetermined period, it is preferable to use a microbial support, and more preferable to use a string-shaped support X, from the viewpoint that the nitrifying bacteria grow and adhere easily. In addition, when acclimatizing the nitrifying bacteria at a water temperature of 10 to 16 ° C. for a predetermined period, the nitrifying bacteria may be floated without using the microorganism carrier.
Moreover, it is preferable to use ammonia nitrogen-containing water to be treated for acclimatization of nitrifying bacteria at a water temperature of 10 to 16 ° C. performed in advance. Specifically, when groundwater is to be treated, it is preferable to acclimatize nitrifying bacteria at a water temperature of 10 to 16 ° C. in advance using the groundwater to obtain inoculum Y. This makes it easy to obtain a high nitrification rate during the nitrification treatment of ammonia nitrogen-containing water.

As a method for adhering nitrifying bacteria to the microorganism carrier, a known method can be adopted, and examples thereof include a method of attaching sludge containing nitrifying bacteria to the microorganism carrier.
In the treatment method of the present invention, from the point that a high nitrification rate is easily obtained stably, it has a tree-like structure in which branches are branched from the trunk, and from the string-like body in which the diameter of the trunk and the diameter of the branches are different. After the nitrifying bacteria are conditioned at a water temperature of 10 to 16 ° C. for a predetermined period of time using the habituating string-shaped carrier, the inoculum Y is obtained, and then the laced-shaped carrier X used for nitrification using the habituating string-shaped carrier. It is preferable to inoculate the inoculum Y and perform nitrification treatment.
It is preferable to use the same cord-like carrier as the cord-like carrier X used for nitrification treatment.

As a method of inoculating the inoculum Y on the string-like carrier X used for nitrification using the habituation-like string carrier, the habituation string-like carrier is subjected to nitrification treatment in ammonia nitrogen-containing water to be treated. A method of contacting the string carrier X used is preferable. Thereby, since the inoculum Y is efficiently seeded and propagated on the string-shaped carrier X used for the nitrification treatment, a high nitrification rate can be obtained in a shorter period of time.
In the treatment method of the present invention, both the string-like carrier X used for the nitrification treatment and the habituation string-like carrier to which the inoculated inoculum Y adheres are immersed in water containing ammonia nitrogen to be treated. They do not necessarily have to be contacted.

  Further, the length of the acclimatized string-like carrier used for seeding is preferably 5% or more, more preferably 10% or more, with respect to the total length of the string-like carrier X used for the nitrification treatment. If the length of the acclimatization support used for seeding is equal to or greater than the lower limit, the inoculum Y is efficiently seeded and proliferated on the support string X used for the nitrification treatment, so that it takes less time High nitrification rate is obtained.

  In the present invention, the ammonia nitrogen concentration of the treated water after nitrification is preferably 0.5 mg / L or less, and more preferably 0.15 mg / L or less. If the concentration of ammonia nitrogen in the treated water is not more than the above upper limit value, the amount of sodium hypochlorite for disinfection used in the latter stage when drinking the treated water can be reduced, which is advantageous in terms of cost. It is.

  In the method for treating ammonia-nitrogen-containing water of the present invention, after performing nitrification treatment by a catalytic oxidation method, disinfection treatment with sodium hypochlorite, filtration treatment, activated carbon treatment, and the like may be performed as necessary.

When the concentration of ammonia nitrogen in the ammonia nitrogen-containing water (raw water) before nitrification exceeds 10 mg / L, nitrate nitrogen is produced by nitrification, so the nitrate nitrogen and nitrite nitrogen of the treated water obtained Concentration may not meet the water quality standard (10 mg / L or less) of the Waterworks Law. In this case, for example, about 70 to 80% of the groundwater yield is nitrified, the remaining 20 to 30% of the groundwater is untreated, and after mixing the treated water after nitrification and untreated groundwater, A method of removing the remaining ammonia nitrogen by a discontinuous point alkali chlorine method may be employed. Thereby, the concentration of nitrate nitrogen and nitrite nitrogen in the treated water can satisfy the water quality standard (10 mg / L or less) of the Waterworks Law.
In this method, most of the ammonia nitrogen in the groundwater is nitrified to nitrate nitrogen by nitrification by a catalytic oxidation method, so that the remaining ammonia nitrogen is small. Therefore, it is not necessary to use a large amount of sodium hypochlorite when removing by the discontinuous point alkali chlorine method, and the cost can be reduced as compared with the conventional method.

(Example embodiment)
Hereinafter, as an example of an embodiment of the method for treating ammonia nitrogen of the present invention, a method for treating groundwater using the treatment apparatus 100 illustrated in FIG. 3 will be described.
The treatment apparatus 100 includes a well pump 110 that pumps groundwater A from a well, a nitrification tank 112 that nitrifies groundwater A pumped by the well pump 110, a sand filtration tower 114 that filters treated water B after nitrification, Activated carbon tower 116 for treating treated water C after filtration with activated carbon, UF membrane filtration device 118 for treating treated water D after activated carbon treatment, residual chlorine meter 120 for measuring residual chlorine concentration, and UF membrane filtration device 118 A treated water tank 122 for storing treated water E after filtration by the process water and a treatment pump 124 for pumping the treated water E from the treated water tank 122 are provided. The residual chlorine meter 120 sends an alarm when it detects the excess or deficiency of sodium hypochlorite in the treated water E. The treatment pump 124 automatically pumps the treated water E from the treated water tank 122 in accordance with the liquid level of the water receiving tank (not shown).

  The nitrification tank 112 is provided with a plurality of string-like carriers 10 and a plurality of air diffusers 126 so as to be positioned below the string-like carriers 10 and over the entire bottom of the nitrification tank 112. Air is supplied to each air diffuser 126 from a blower 128 through an air inlet tube 129. As described above, the processing apparatus 100 can perform aeration on the entire surface by using the plurality of aeration tubes 126 arranged in the entire bottom portion of the nitrification tank 112.

  In the processing apparatus 100 of this example, the string-like carrier 10 is installed such that the axial direction of the trunk 12 is the vertical direction. Each string-like carrier 10 is preferably arranged so that the branch portions of adjacent string-like carriers partially overlap in plan view.

In the groundwater treatment method using the treatment apparatus 100, groundwater A containing one or both of methane and hydrogen sulfide and ammonia nitrogen is pumped from the well by the well pump 110 and sent to the nitrification tank 112. The nitrification treatment is performed by the contact oxidation method using the string-like carrier 10 to which the nitrifying bacteria adhere. During the nitrification process, air is supplied from the blower 128 to the diffuser pipe 126 through the air introduction pipe 129, and the whole surface is aerated at an aeration intensity of 2 to 10 m ³ / m ³ · hr. Thereby, methane and hydrogen sulfide contained in the groundwater A are released into the gas phase while maintaining the aerobic condition. Therefore, ammonia nitrogen is efficiently nitrified into nitrate nitrogen or nitrite nitrogen by the nitrification action by nitrifying bacteria, and treated water B having a reduced ammonia nitrogen concentration is obtained.

  Next, sodium hypochlorite is added to the treated water B after nitrification treatment, and ammonia nitrogen remaining in the treated water B is removed by the discontinuous point alkali chlorine method, and then sent to the sand filtration tower 114. Perform filtration. The treated water C after the filtration treatment is sent to the activated carbon tower 116 and the sodium hypochlorite remaining in the treated water C is removed by contacting with the activated carbon. The treated water D after the activated carbon treatment is added with sodium hypochlorite for disinfection, then sent to the UF membrane filtration device 118 and filtered, and the resulting treated water E is stored in the treated water tank 122. For the treated water E after filtration by the UF membrane filtration device 118, the residual chlorine concentration is monitored by measurement with the residual chlorine meter 120. The treated water E stored in the treated water tank 122 is sent to a predetermined place by the treatment pump 124.

The method for treating ammonia-nitrogen-containing water according to the present invention described above does not require an ion exchange tower or a pretreatment sand filtration tower and has a low initial cost compared to the conventional method described with reference to FIG. Moreover, since the cost increase resulting from consumption of sodium chloride or sodium hypochlorite as an ion exchange medium can be prevented, the running cost is low.
In addition, the treatment method of the present invention is easier to control the nitrification treatment than the nitrification denitrification method in which two reaction systems, a nitrification reaction under an aerobic condition and a denitrification reaction under an anaerobic condition, exist. High nitrification rate can be realized stably. For this reason, when the treated water is used as drinking water, it is particularly advantageous in terms of cost since quantitative control is easy when sodium hypochlorite for disinfection is added later.

Further, in the treatment method of the present invention, even if either or both of methane and hydrogen sulfide are contained in the ammonia nitrogen-containing water, the component is removed by aeration with an aeration intensity of 2 to 10 m ³ / m ³ · hr. Since it can be diffused and removed in the phase, problems due to methane and hydrogen sulfide are suppressed, and the ammonia nitrogen concentration can be stably reduced.

In addition, when the string-shaped carrier X is used as the microorganism carrier, nitrifying bacteria are easily grown and bubbles are easily refined, so that methane and hydrogen sulfide can be efficiently removed. Can be reduced. Therefore, the amount of sodium hypochlorite for disinfection is further reduced, which is further advantageous in terms of cost.
Moreover, if the inoculum Y obtained by previously acclimating the nitrifying bacteria at a water temperature of 10 to 16 ° C. for a predetermined period is used as the nitrifying bacteria, a high nitrification rate can be maintained even if the temperature of the ammonia nitrogen-containing water to be treated is low. In addition, water temperature control equipment is not required and costs can be further reduced.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by the following description.
[Measurement of nitrification rate]
Measurement of the nitrification rate in this example was performed as follows. The ammonia nitrogen concentration Q _{A in} the ground water before treatment and the ammonia nitrogen concentration Q _B in the treated water after treatment were measured using HACH manufactured by Toa DKK Corporation, and the nitrification rate P was calculated by the following equation.
P = {(Q _A −Q _B ) / Q _A } × 100

[String-shaped carrier X]
As the string-shaped carrier X, the trunk portion 12 illustrated in FIGS. 1 and 2 has a braided structure composed of two thick threads and four thin threads, and the clockwise thread and the counterclockwise that constitute the braided structure. The string-like carrier 10 in which the annular branch portions 14A and 14B are formed by each of the yarns was used. Details of the string-like carrier 10 used are shown below.
Total length: 200 mm.
Surface area per meter of length: 4.5 m ² / m.
Diameter of trunk 12: 5 mm.
The diameter of the annular branch portion 14A: 2 mm.
Diameter of annular branch 14B: 0.25 mm.
Thick thread forming the trunk portion 12 and the annular branch portion 14A: made of polypropylene.
Thin thread forming the trunk 12 and the annular branch 14B: made of vinylon.

[Example 1]
The nitrification treatment by the contact oxidation method of groundwater was continuously performed using the entire aeration type treatment apparatus 100A illustrated in FIG.
The processing apparatus 100A includes a nitrification tank 130 composed of a 10 liter water tank having a size of 20 cm × 20 cm × effective water depth 25 cm, a plurality of air diffusion pipes 132 disposed in the entire bottom of the nitrification tank 130, and each air diffusion pipe 132 and air introduction pipe 134. And a blower 136 connected thereto. The water temperature in the nitrification tank 130 can be adjusted by a heater.
A plurality of string-like carriers 10 to which sludge containing nitrifying bacteria was attached were arranged in the nitrification tank 130. Each string-like carrier 10 is installed by being suspended in the vertical direction, the pitch of each string-like carrier 10 is set to 100 mm, and the tips of the annular branch portions 14 of adjacent string-like carriers 10 are slightly in contact with each other. did.
As the air diffuser 132, a 15A polyvinyl chloride tube provided with a plurality of circular holes with a diameter of 3 mm was used.

Groundwater A (ammonia nitrogen concentration: 2.5-3.0 mg / L, methane concentration: 2-3 volume ppm, hydrogen sulfide concentration: 0 volume ppm) is continuously supplied to the nitrification tank 130, and the residence time (HRT ) Was continuously extracted so that 1 hour would be 1 hour. The temperature of groundwater A in the nitrification tank 130 was maintained at 20 ° C.
In addition, aeration is performed by generating bubbles from the diffuser tube 132 positioned below the string-like carrier 10, and the aeration strength is 1.0 m ³ / m ³ · hr, 1.5 m ³ / m ³ · hr. , 3.0 m ³ / m ³ · hr, and stepwise.

[Example 2]
Groundwater A (ammonia nitrogen concentration: 2.5 to 3.0 mg / L, methane concentration: 2 to 3 volume ppm) as in Example 1 except that the partial aeration type processing apparatus 100B illustrated in FIG. 6 was used. , Hydrogen sulfide concentration: 0 volume ppm).
The processing apparatus 100B disperses the air diffuser 132 in the nitrification tank 130 near the side wall surface of the nitrification tank 130, and provides a partition plate 138 between the string-like carrier 10 and the air diffuser 132 disposed in the nitrification tank 130. Except that the water flow generated along with the bubbles generated from the air diffuser 132 reaches the string-like carrier 10 from above the partition plate 138 and circulates from below the partition plate 138 toward the air diffuser 132. This is the same as the processing apparatus 100A.
FIG. 7 shows changes in the nitrification rate of groundwater A during the treatment in Examples 1 and 2.

As shown in FIG. 7, in Example 1, the nitrification rate was about 10% or lower during the periods where the aeration intensity was 1.0 m ³ / m ³ · hr and 1.5 m ³ / m ³ · hr. However, when the aeration intensity was set to 3.0 m ³ / m ³ · hr, the nitrification rate increased rapidly and became about 95%. The same tendency was observed in Example 2, although the aeration intensity was 1.0 m ³ / m ³ · hr, 1.5 m ³ / m ³ · hr, while the nitrification rate was about 10% or lower, When the aeration intensity was set to 3.0 m ³ / m ³ · hr, the nitrification rate increased rapidly and became about 85 to 90%.
The increase in the nitrification rate in Examples 1 and 2 is because methane in the groundwater A was diffused into the gas phase by aeration with an aeration intensity of 3.0 m ³ / m ³ · hr.

[Example 3 (reference example)]
A string-like carrier 10 to which sludge containing nitrifying bacteria is attached is placed in a nitrification tank composed of a cylindrical polyvinyl chloride pipe having a diameter of 60 mm and an effective height of 300 mm, and groundwater (ammonia nitrogen concentration: 2.5 ˜3.0 mg / L, methane concentration: 0 volume ppm, hydrogen sulfide concentration: 0 volume ppm), and nitrification was performed in a batch manner for 2 hours while aerated. The temperature of groundwater during nitrification was adjusted to 25 ° C. using a constant temperature water bath. The aeration intensity was 1.5 m ³ / m ³ · hr.

[Example 4 (reference example)]
A nitrification treatment by a catalytic oxidation method was performed in the same manner as in Example 1 except that ceramic as a granular carrier was used instead of the string-like carrier 10 as the microorganism carrier.

[Example 5 (reference example)]
A nitrification treatment by a catalytic oxidation method was performed in the same manner as in Example 1 except that a fishing net, which was a net-like carrier, was used instead of the string-like carrier 10 as the microorganism-like carrier.

  Regarding Examples 3 to 5, when the nitrification rate of ammonia nitrogen 2 hours after the start of the treatment was measured, the nitrification rate was 70 to 93% in Examples 4 and 5 using a granular carrier and a net carrier. On the other hand, in Example 3 using the string carrier 10, the nitrification rate was as high as 95 to 98%.

[Example 6 (reference example)]
The nitrification treatment by the contact oxidation method of groundwater was continuously performed using the treatment apparatus 100C illustrated in FIG.
The treatment apparatus 100C includes a nitrification tank 140 formed of a cylindrical polyvinyl chloride pipe, a constant temperature water tank 142 in which the nitrification tank 140 is immersed, an aeration pipe 144 disposed at the bottom of the nitrification tank 140 and the constant temperature water tank 142, A blower 148 connected by a trachea 144 and an air introduction pipe 146, and a heater 150 and a chiller unit 152 for adjusting the water temperature in the constant temperature water tank 142 are provided. The constant temperature water is supplied from the constant temperature water tank 142 to the chiller unit 152 by the pump 154 and is returned to the constant temperature water tank 142 and circulated. The air diffuser 144 in the nitrification tank 140 was disposed at the center of the nitrification tank 140 in plan view.
The string-like carrier 10 to which sludge containing nitrifying bacteria is attached is placed in the nitrification tank 140, and ground water A (ammonia nitrogen concentration: 2.5 to 3.0 mg / L, methane concentration: 0 volume) is placed in the nitrification tank 140. ppm, hydrogen sulfide concentration: 0 volume ppm) was continuously supplied, and the treated water B was continuously extracted so that the residence time (HRT) was 1 hour. The temperature of the groundwater A in the nitrification tank 140 was lowered from 25 ° C. to 11 ° C. step by step by adjusting the water temperature in the constant temperature water tank 142 with the heater 150 and the chiller unit 152.
Aeration was performed by generating bubbles from the air diffuser 144 located below the string-like carrier 10, and the aeration intensity was 1.5 m ³ / m ³ · hr.

[Example 7 (reference example)]
The diffuser tube 144 in the nitrification tank 140 is unevenly distributed near the side wall surface of the nitrification tank 140, and a partition plate is provided between the string-like carrier 10 disposed in the nitrification tank 140 and the diffuser pipe 144, and generated from the diffuser pipe 144. The water flow generated along with the bubbles reaches the string-like carrier 10 from above the partition plate, and circulates from the lower side of the partition plate toward the air diffuser 144 to be circulated. A processing device was used. Using the treatment apparatus, nitrification treatment by a catalytic oxidation method was performed in the same manner as in Example 6 except that the temperature of the groundwater A in the nitrification tank 140 was gradually lowered from 25 ° C. to 9 ° C.
FIG. 9 shows changes in the water temperature and nitrification rate of groundwater A during treatment in Examples 6 and 7.

As shown in FIG. 9, in Example 6, the water temperature during the treatment was gradually reduced from 25 ° C., and as the water temperature decreased to 16 ° C., a decrease in the nitrification rate was confirmed as the water temperature decreased. However, when the water temperature was lowered to 14 ° C. and the water temperature was maintained for a long period of time, the nitrification rate rapidly increased from about 40 days after the water temperature was set to 14 ° C. and reached about 95%. After that, when the water temperature was lowered by 1 ° C, when the temperature was lowered, the nitrification rate once decreased, but the nitrification rate recovered in a short period of time, and the nitrification rate was maintained at about 95% even at a water temperature of 11 ° C. It was done. The same tendency was also observed in Example 7, and the nitrification rate was maintained at about 95% even at a water temperature of 9 ° C.
Thus, a new finding contrary to common sense was obtained that the activity of nitrifying bacteria was greatly changed by maintaining the water temperature at 14 ° C. for a long time, and that a high nitrification rate could be maintained even when the water temperature was low.

[Example 8 (reference example)]
A nitrification treatment by a catalytic oxidation method was performed in the same manner as in Example 6 except that the temperature of the groundwater A during the treatment was maintained at 25 ° C. and the HRT was gradually reduced from 5.1 hours to 0.5 hours stepwise.
FIG. 10 shows changes in the ammonia nitrogen concentration and nitrification rate of the groundwater A and the obtained treated water B used for the treatment.

  When HRT was operated for 5.1 hours, the nitrification rate increased to about 95%. After that, when the HRT was shortened step by step, it was confirmed that the nitrification rate increased as a result of maintaining for a certain period of time, although the nitrification rate once decreased, as shown in FIG. And even if HRT was 0.5 hour, the nitrification rate of about 95% similar to that when HRT was 5.1 hour was obtained.

[Example 9 (reference example)]
After the water temperature was lowered stepwise in the same manner as in Example 6, the HRT was shortened stepwise in the same manner as in Example 8, and the nitrification rate became about 95% under conditions of a water temperature of 9 ° C. and an HRT of 0.5 hours. At this stage, the supply of groundwater A, water temperature control and aeration were all stopped and left in an environment at room temperature of 5 to 10 ° C. for 8 days. Thereafter, when the nitrification treatment was resumed under conditions of a water temperature of 9 ° C. and an HRT of 0.5 hour, the nitrification rate increased to about 95% in about 2 days after the resume.

  From the results of Example 9, it was found that the nitrifying bacteria maintained for a predetermined period under a load by reducing the water temperature and shortening the HRT can exhibit sufficient nitrifying activity even when used in a harsh environment.

[Example 10 (reference example)]
A container having an effective capacity of 2 L was filled with a string-like carrier 10 having no nitrifying bacteria attached thereto at a filling density of 500 m / m ³ . Next, sludge containing an inoculum obtained in the same manner as in Example 4 (nitrifying bacteria whose nitrification rate has increased to about 95% under conditions of a water temperature of 14 ° C.) adheres to the length 1 m of the string-like carrier 10. The string-like carrier 10 is brought into contact with a length of 0.1 m, that is, 10%. Further, while continuously supplying groundwater, treated water was continuously extracted so that HRT was 4 hours, and nitrification was performed for 23 days.
The nitrification treatment was carried out in two ways: one in which the temperature of groundwater during treatment was adjusted to 12 ° C. and one in which the temperature was adjusted to 20 ° C. The string-like carrier 10 to which the sludge containing the inoculum adhered was removed after 14 days from the start of the treatment in the example in which the water temperature was adjusted to 12 ° C, and after 8 days from the start of the treatment in the example in which the water temperature was adjusted to 20 ° C.
Moreover, the process which adjusted the temperature of groundwater to 20 degreeC was implemented by the same method except not using the string-like carrier 10 to which the sludge containing inoculum adhered.

  FIG. 11 shows changes in the concentration of ammonia nitrogen in groundwater and treated water before treatment in Example 10. “Treatment water with inoculum” in FIG. 11 is a system in which nitrification treatment is performed by bringing the string-like carrier 10 with the seed bacteria attached into contact with the string-like carrier 10 with no nitrifying bacteria attached at the above ratio. Indicates. In addition, “treated water without inoculum” refers to a system in which the string-like carrier 10 to which the inoculum is attached is not used.

As shown in FIG. 11, when the string-like carrier 10 to which the sludge containing the inoculum is attached is used, after 8 days from the start of treatment in the system at a water temperature of 20 ° C., 14 days after the start of treatment in the system at a water temperature of 12 ° C., The ammonia nitrogen concentration in the treated water was sufficiently reduced. On the other hand, in the system that does not use the string-like carrier 10 to which the sludge containing the inoculum adheres, that is, in which the inoculum is not inoculated, the ammonia nitrogen concentration of the treated water did not decrease even 20 days after the start of the treatment.
This result suggests that by inoculating inoculated bacteria in advance on the microorganism carrier, the main operation of nitrification treatment can be started in a very short period even under severe conditions.

  In Examples 1 to 10, the decrease in ammonia nitrogen contained in the groundwater is all converted to nitrate nitrogen by nitrification, and the nitrite nitrogen concentration in the resulting treated water is all based on the Waterworks Law. It was below the reference value (0.04 mg / L).

  DESCRIPTION OF SYMBOLS 10 ... String-like support body, 12 ... Trunk part, 14, 14A, 14B ... Annular branch part.

Claims (8)

Including methane and / or hydrogen sulfide and ammonia nitrogen, ground water, to ammonium nitrogen-containing water is river water and / or lake water, without the use of nitrification denitrification, adhere to microbial support nitrification A method for treating ammonia-nitrogen-containing water, characterized by performing nitrification by a catalytic oxidation method utilizing bacteria and aeration with an aeration intensity of 2 to 10 m ³ / m ³ · hr during the nitrification treatment. Nitrifying bacteria attached to a microorganism carrier without using nitrification denitrification method for ammonia nitrogen-containing water containing methane and / or hydrogen sulfide and ammonia nitrogen and having an ammonia nitrogen concentration of 15 mg / L or less Nitrification by a catalytic oxidation method using aeration, and aeration strength of 2 to 10 m during the nitrification treatment ³ / M ³ A method for treating ammonia nitrogen-containing water, characterized by aeration with hr. The nitrification treatment is performed such that nitrate nitrogen and nitrite nitrogen are 10 mg / L or less and nitrite nitrogen is 0.04 mg / L or less in the treated water after the nitrification treatment. A method for treating ammonia nitrogen-containing water as described in 1. above. The microbial carrier is a cord-like carrier having a dendritic structure in which a branch portion is branched from a trunk portion, and comprising a string-like body having a diameter different from that of the trunk portion and a diameter of the branch portion . The method for treating ammonia-nitrogen-containing water according to any one of the above. The nitrification treatment is performed on a plurality of the string-shaped carriers so that the axial direction of the trunk portion is a vertical direction and the tip portions of the branch portions of adjacent string-shaped carriers overlap each other in a plan view. The method for treating ammonia nitrogen-containing water according to claim 4 , which is disposed in a nitrification tank. The method for treating ammonia-nitrogen-containing water according to any one of claims 1 to 5 , wherein the entire nitrification tank in which the nitrification treatment is performed is aerated. While supplying the ammonia nitrogen-containing water to the nitrification tank for performing the nitrification treatment, the nitrification tank is a continuous nitrification process in which treated water is extracted from the nitrification tank, and the residence time (HRT) of the ammonia nitrogen-containing water in the nitrification tank The treatment method of ammonia nitrogen-containing water according to any one of claims 1 to 6 , wherein the treatment time is 0.5 to 2 hours. The method for treating ammonia-nitrogen-containing water according to any one of claims 1 to 7 , wherein the nitrification treatment is performed on the ammonia-nitrogen-containing water without performing an aeration treatment as a pretreatment.

Images