JP2019037912A - Denitrification treatment method and denitrification treatment apparatus for ammonia nitrogen containing wastewater - Google Patents

Abstract

To perform stable ANAMMOX denitrification treatment by reducing pH rise when introducing raw water to maintain a pH range where activity of an ANAMMOX reaction is not decreased without using a pH adjuster or after reducing an amount of its use, when treating ammonia waste water containing high pH or high IC concentration by subjecting it to SBR single tank type ANAMMOX treatment.SOLUTION: There is provided a denitrification treatment method for ammonia nitrogen containing wastewater, which is a batch denitrification treatment using a reaction tank containing mixed sludge of ammonia oxidizing bacteria and ANAMMOX bacteria using ammonia nitrogen containing wastewater as raw water. In this method, a raw water introduction step of introducing the raw water into the reaction tank and an aeration step are performed simultaneously.SELECTED DRAWING: Figure 1

Description

The present invention is a batch-type (SBR) one-tank type ANAMOX process, which contains ammoniacal nitrogen-containing wastewater, particularly wastewater with high pH or high inorganic carbonate concentration containing ammoniacal nitrogen, such as dehydrated filtrate of methane fermentation digestive juice and chemical factory. The present invention relates to a denitrification treatment method and denitrification treatment apparatus for ammonia nitrogen-containing wastewater that reduces the amount of pH adjuster used when treating wastewater and the like.
Here, the one tank type ANAMMOX process is a waste water treatment process in which ammonia nitrogen nitritation and denitrification by the ANAMOX reaction are carried out in the same tank by using mixed sludge of ammonia oxidizing bacteria and ANAMMOX bacteria to remove nitrogen. Point to.

  As a denitrification process for ammonia nitrogen-containing wastewater, ANAMMOX bacteria, which are autotrophic microorganisms using ammonia nitrogen as an electron donor and nitrite nitrogen as an electron acceptor, are used. An ANAMOX process in which nitrogen is reacted to denitrify is known.

  The wastewater treatment process using the ANAMMOX reaction has been conventionally performed in a two-tank type in which a nitrite-type nitrification tank and an ANAMMOX denitrification tank are provided and the treatment is performed in the order of nitritation → ANAMMOX reaction. A one-tank type ANAMMOX process has been developed in which nitritation and ANAMMOX reaction are carried out in one tank using sludge in which bacteria and ANAMMOX bacteria coexist (Patent Document 1).

  The single tank type ANAMMOX process can be processed in either batch (SBR) (Patent Document 2) or continuous (Patent Document 3) reaction tanks, but a solid-liquid separation device is not required and the device structure is simple. Often, an SBR reactor is used.

The SBR type reaction tank is a reaction tank that performs the following operation.
1. Raw water is put into the reaction tank.
2. By aeration in the reaction tank, the one-tank type ANAMOX reaction is advanced to remove ammonia nitrogen from the water as nitrogen gas.
3. Stop aeration and let it stand to settle sludge containing ammonia-oxidizing bacteria and ANAMMOX bacteria.
4). The supernatant water is discharged as treated water.
5. New raw water is charged again into the reaction vessel, and operations 2 to 4 are repeated.

It is known that the activity of ANAMOX bacteria decreases in the high pH region exceeding pH 8.3 compared with the activity at pH 6.7 to 8.3 (Non-patent Document 1). It is necessary to adjust the pH to about 7-8 so that the activity of the ANAMOX bacteria does not decrease.
However, when the pH of the raw water is high, the pH of the liquid in the tank rises when the raw water is charged into the reaction tank.

Therefore, in Patent Document 2, in the SBR reactor shown in FIG. 3, the pH is adjusted by adding acid to the raw water according to the following procedure.
(1) Raw water is introduced into the reaction tank 1 from the raw water introduction path L1 by the pump P1.
(2) Air as an oxygen-containing gas is introduced into the reaction tank 1 from the air introduction path L4, and the nitritation and the ANAMOX reaction proceed simultaneously.
(3) At this time, the pump P2 is controlled by the pH measuring device pH so that the pH of the reaction solution becomes 7 to 8, and sodium carbonate is injected as a pH adjuster from the drug introduction path L2.
(4) After completion of the reaction, aeration is stopped and the mixture is allowed to stand to precipitate sludge containing ammonia-oxidizing bacteria and ANAMMOX bacteria.
(5) The supernatant water is discharged as treated water from the treated water extraction passage 3 by the pump P3.
(6) Fresh raw water is again charged into the reaction tank 1, and the above operations (2) to (5) are repeated.
In FIG. 3, 3 is a reaction liquid 3 in which biological sludge 2 containing ANAMOX bacteria and ammonia oxidizing bacteria is dispersed, 4 is an air diffuser, 5 is a take-out part, and 6 is a control device. The dissolved oxygen concentration in the reaction tank 1 is measured by the dissolved oxygen concentration measuring device DO, and the measured value of the dissolved oxygen concentration measuring device DO and the measured value of the pH measuring device pH are input to the control device 6.

Special table 2001-506535 gazette Japanese Patent No. 5347221 JP 2010-221193 A

Wastewater Engineering 5th Edition

In order to prevent the pH of the liquid in the tank from being increased by the raw water, when a pH adjuster (for example, sodium carbonate) is added to adjust the pH as in Patent Document 2, it is necessary to add the pH adjuster and the ANAMOX reaction. Further, inorganic carbon (IC) necessary for the nitrification reaction is volatilized as CO ₂ gas at dissociation equilibrium, so that the amount of IC added to the ANAMOX reaction tank increases to compensate for this.
Even if the pH of the raw water is 8.3 or less, the raw water containing a high concentration of inorganic carbon (IC) may increase in pH due to carbonic acid stripping due to aeration. To face.

  As described above, when the raw water pH is high or when the raw water contains a large amount of IC, the pH of the solution in the reaction tank may increase, but it is not possible to simply adjust the pH by adding a pH adjuster. Not desirable.

  In the present invention, when wastewater containing ammonia nitrogen containing high pH or high IC concentration is treated in the SBR single tank type ANAMMOX process, the pH of the reaction tank rises when raw water is introduced, and the activity of the ANAMOX bacteria decreases. An object of the present invention is to provide a technique for preventing a decrease in nitrogen removal rate without using a pH adjuster or after reducing the amount of use.

As a result of repeated investigations to solve the above problems, the present inventors conducted aeration at the time of introducing raw water into the ANAMMOX reaction tank, so that the nitritation and the ANAMMOX reaction proceeded even at the time of introducing raw water, thereby generating ammonia nitrogen. It was found that the pH increase due to the inflow of high pH raw water can be suppressed by removing and reducing the pH by removing ammoniacal nitrogen.
That is, the gist of the present invention is as follows.

[1] A method of batch-type denitrification using ammonia nitrogen-containing wastewater as raw water and a reaction tank containing mixed sludge of ammonia-oxidizing bacteria and ANAMMOX bacteria, in the raw water introduction step to the reaction tank A method for denitrification of wastewater containing ammoniacal nitrogen, wherein the aeration step is performed simultaneously.

[2] In [1], the ratio of the raw water introduction process time (hereinafter referred to as “raw water introduction time”) and the aeration process time (hereinafter referred to as “aeration time”) (raw water introduction time / percentage of aeration time) 40) to 100%, a denitrification method for ammonia nitrogen-containing wastewater.

[3] In [1], the pH in the reaction vessel is measured, and when the measured pH value exceeds 8.3, the introduction of the raw water is stopped. Nitrogen treatment method.

[4] The denitrification method for ammonia nitrogen-containing wastewater according to any one of [1] to [3], wherein the pH of the raw water is more than 8.3 and 10 or less.

[5] In any one of [1] to [4], the inorganic nitrogen concentration of the raw water is 150 to 3,000 mg / L.

[6] The denitrification method for ammonia nitrogen-containing wastewater according to any one of [1] to [5], wherein the raw water is a dehydrated filtrate of anaerobic digestive juice.

[7] A denitrification apparatus for carrying out the denitrification method for ammonia nitrogen-containing wastewater according to [1], [2], [5] or [6], comprising ammonia oxidizing bacteria and ANAMMOX bacteria A reaction tank containing mixed sludge, a raw water introduction means for introducing ammonia nitrogen-containing wastewater as raw water into the reaction tank, a treated water discharge means for discharging denitrified treated water from the reaction tank, A batch-type single tank type ANAMMOX reactor having aeration means for aeration of a reaction liquid, operation of the raw water introduction means, and control means for controlling the operation of the aeration means, the control means comprising the raw water introduction An apparatus for denitrifying ammonia nitrogen-containing wastewater, wherein the aeration means controls the aeration of the inside of the reaction tank when the raw water is introduced by the means.

[8] A denitrification apparatus for carrying out the denitrification method for ammonia nitrogen-containing wastewater according to [3] or [4], comprising a reaction tank containing mixed sludge of ammonia-oxidizing bacteria and ANAMOX bacteria Raw water introduction means for introducing ammonia nitrogen-containing wastewater into the reaction tank as raw water, treated water discharge means for discharging denitrification treated water from the reaction tank, and aeration means for aeration of the reaction liquid in the reaction tank; A batch-type single tank type ANAMOX reactor having pH measuring means for measuring the pH of the liquid in the reaction tank, operation of the raw water introduction means, and control means for controlling the operation of the aeration means, When the raw water is introduced by the raw water introduction means, the control means controls the aeration means to aerate the inside of the reaction tank. If the measured value of the pH measurement means exceeds 8.3, the control means uses the raw water introduction means. Stop introducing raw water That control the denitrification device ammonium nitrogen-containing waste water and performing.

  According to the present invention, when ammonia-containing nitrogen-containing wastewater having a high pH or high IC concentration is treated by the SBR type one-tank type ANAMMOX process, a pH adjuster is not used or the amount used is reduced. In addition, the pH of the solution in the reaction tank when the raw water is introduced can be maintained in a range where the activity of the ANAMOX reaction does not decrease, and the denitrification treatment by the ANAMOX reaction can be performed stably and efficiently.

It is a systematic diagram of the SBR type 1 tank type ANAMMOX reaction tank explaining an example of the raw water introduction and aeration control method by the present invention. It is a systematic diagram of the SBR type one tank type ANAMMOX reaction tank explaining the other example of the raw water introduction by this invention, and the control method of aeration. It is a systematic diagram showing a general SBR type one tank type ANAMMOX reaction tank.

  Hereinafter, embodiments of the present invention will be described in detail.

  In the present invention, aeration is carried out at the same time when raw water is introduced into the SBR type one-tank type ANAMMOX reaction tank, and nitritation of ammonia nitrogen and ANAMOX of nitrite nitrogen and ammonia nitrogen are introduced at the time of raw water introduction into the reaction tank. Progress denitrification by reaction.

The working mechanism of the present invention for performing aeration when introducing raw water into the reaction tank is as follows.
The reaction formulas of the nitritation of ammonia nitrogen and the ANAMOX reaction are as shown in the following formulas 1 and 2. The one-tank type ANMAMOX reaction that summarizes the formulas 1 and 2 is as shown in the following formula 3. In the one-tank type AAMAMOX reaction, the pH decreases with the removal of ammoniacal nitrogen. In accordance with the present invention, aeration is started at the same time as the introduction of raw water, and the raw water is gradually introduced (over time at a low flow rate), so that the pH increase due to the introduction of raw water is offset by the pH decrease due to the removal of ammonia nitrogen, As a result, it becomes possible to operate by maintaining the pH of the liquid in the tank in a pH range (pH 6.7 to 8.3) that does not inhibit the ANAMMOX bacteria.
<Nitrite of ammoniacal nitrogen>
1.0NH ₄ ⁺ + 1.5O ₂ → 1.0NO ₂ + H ₂ O + 2.0H ⁺ Formula 1
<ANAMMOX reaction>
1.0 NH ₄ ⁺ +1.32 NO ₂ ⁻ +0.066 HCO ₃ ⁻ →
1.02N ₂ + 0.26NO ₃ ⁻ + 0.066CH ₂ O _0.5 N _0.15
+ 2.03H ₂ O + 0.13OH ^- Formula 2
<Denitrification by one tank type ANAMMOX reaction>
1.0NH ₄ ⁺ + 0.65O ₂ →
0.44N ₂ + 0.11NO ₃ ⁻ + 1.14H ⁺ + 1.43H ₂ O Formula 3

  Conventionally, in the SBR type single tank type ANAMOX process, raw water is not introduced into the reaction tank at a low flow rate over time while aeration of the reaction tank is performed. That is, after the reaction is completed, aeration is stopped and left standing, and after sludge is settled and the supernatant water is discharged as treated water, the raw water is introduced into the reaction tank as quickly as possible without aeration. Normally, when the water level in the inside reaches a predetermined position, the introduction of raw water is stopped, and then aeration is started to perform the reaction. Thus, conventionally, the introduction of raw water in a short time while aeration is stopped tends to maintain a high reaction rate of ammonia oxidizing bacteria and ANAMMOX bacteria by maintaining a high ammonia nitrogen concentration in the reaction tank. This is because there is no idea that aeration is performed in parallel with the introduction of raw water in the conventional SBR single-tank type ANAMOX process.

  The present invention is suitably applied to the treatment of SBR type one-tank type ANAMMOX process using ammonia nitrogen-containing wastewater having a high pH or high IC concentration, which tends to cause an increase in the pH of the liquid in the tank due to the introduction of raw water, as raw water. The

  In the present invention, the ammonia nitrogen-containing wastewater to be treated may be any liquid containing ammonia nitrogen or organic nitrogen that can be denitrified by contacting with sludge containing ammonia oxidizing bacteria and ANAMMOX bacteria, A high effect is obtained in wastewater containing a high concentration of ammoniacal nitrogen and having a pH exceeding 8.3 or wastewater having a high IC concentration.

The pH of the ammoniacal nitrogen-containing wastewater to be treated in the present invention is preferably more than 8.3 and 10 or less. If the raw water has a pH of 8.3 or less, stable treatment is often possible without applying the present invention. In the case of raw water having a high pH exceeding 10 pH, the present invention can be applied with a sufficient pH. In some cases, the reduction effect cannot be obtained. For the same reason, the IC concentration of the ammoniacal nitrogen-containing waste water targeted in the present invention is preferably 150 to 3,000 mg / L.
Moreover, it is preferable that the ammoniacal nitrogen density | concentration of the ammoniacal nitrogen containing waste water used as a process target by this invention is 200-7000 mg / L.
Specific examples of such wastewater include dehydrated filtrate of anaerobic digestive juice (methane fermentation digestive juice) and various chemical factory wastewater. The water quality of the dehydrated filtrate of the anaerobic digestion liquid is usually an ammoniacal nitrogen concentration of 500 to 7,000 mg / L, a pH of 7.7 to 9.2, and an IC concentration of 1,000 to 3,000 mg / L. .

  The ammonia-oxidizing bacterium used for nitritation of ammonia nitrogen in the present invention is a bacterium conventionally used for nitritation of ammonia nitrogen, and oxidizes ammonia nitrogen under aerobic condition to nitrite. It is a bacterium that converts to natural nitrogen. Such nitrite bacteria can be generated by maintaining the treatment liquid containing ammoniacal nitrogen under aerobic condition, but the sludge collected from the nitritation step of organic wastewater treatment is used as it is or It can be used by attaching to a biological reaction member.

  The ANAMMOX bacterium used for denitrification in the present invention is a bacterium belonging to Plantomycins, which is a denitrification bacterium that reacts ammonia nitrogen and nitrite nitrogen in an anaerobic atmosphere to directly convert to nitrogen gas. Unlike the heterotrophic denitrification bacteria used in conventional denitrification, such ANAMOX bacteria are autotrophic bacteria, and therefore, methanol and the like that are necessary for conventional denitrification bacteria during denitrification No additional nutritional sources are required. In addition, ANAMMOX bacteria react with ammonia nitrogen and nitrite nitrogen to convert them directly into nitrogen gas, so that ammonia nitrogen and nitrite nitrogen can be removed simultaneously, and no harmful by-products are produced. Such ANAMMOX bacteria can be generated by anaerobic reaction of a liquid containing ammoniacal nitrogen and nitrite nitrogen to denitrify, but the sludge collected from the denitrification process of the nitrogen-containing liquid Can be used as is or attached to a biological reaction member.

  The mixed sludge of ammonia oxidizing bacteria and ANAMMOX bacteria used in the present invention is a mixed sludge containing such ammonia oxidizing bacteria and ANAMMOX bacteria. These bacteria may be contained in the sludge in a mixed state in the mixed sludge, but biological sludge constructed so that ammonia oxidizing bacteria cover the surface of the ANAMMOX bacteria is preferable, and is particularly supported inside the carrier. The biological sludge formed so that ammonia oxidizing bacteria may cover the surface of the anammox bacteria prepared is preferable. Such sludge is formed by continuing the treatment in the presence of the carrier in the reaction solution. When biological sludge adheres to such a carrier, the surface side becomes aerobic, so ammonia oxidizing bacteria predominate, and the inside becomes anaerobic, so ANAMMOX bacteria predominate, and biological sludge having the above-described structure is likely to be formed. Instead of the carrier, biological sludge formed so that ammonia oxidizing bacteria may cover the surface of the ANAMOX granules obtained by self-granulating ANAMOX bacteria.

  As the oxygen-containing gas used for aeration in the present invention, a gas containing oxygen can be used without limitation. Air is preferred as the oxygen-containing gas, but other gases can be used.

For example, when the present invention is carried out in the SBR reactor shown in FIG. 3, it can be carried out in the following procedure.
(1) The introduction of raw water containing ammonia nitrogen into the reaction tank 1 is started by the operation of the pump P1, and the air diffuser 4 is operated to enter the reaction tank 1 of air (oxygen-containing gas) from the air introduction path L4. The introduction of water and aeration inside the tank allows the raw water introduction and denitrification reaction to proceed simultaneously. The raw water introduction time is preferably 40 to 100% of the aeration time. Or, instead of time control, measure the pH in the tank, and if the pH in the tank falls below 8.3, introduce raw water until it reaches pH 8.3, and if the pH exceeds 8.3, introduce raw water. The aeration can be stopped and only aeration is performed, and the operation of restarting the introduction of raw water can be repeated when the pH of the solution in the tank becomes 8.3 or lower.
(2) After completion of the reaction, aeration is stopped and the mixture is allowed to stand to precipitate sludge containing ammonia-oxidizing bacteria and ANAMMOX bacteria.
(3) The supernatant water is discharged as treated water from the treated water outlet L3 by the pump P3.
(4) Aeration is performed while introducing fresh raw water into the reaction tank 1 again, and the above operations (1) to (3) are repeated.

  The raw water introduction and aeration control method according to the present invention will be described below with reference to FIGS. In FIGS. 1 and 2, members having the same functions as those in FIG. 1 and 2, the dissolved oxygen concentration measuring device DO and its control device 6 in FIG. 3 are not shown.

  FIG. 1 shows an SBR type one-tank type ANAMOX reaction tank 1 that performs a raw water introduction process and an aeration process by time control. A pump P1 is operated by a controller 10 to introduce raw water into the reaction tank 1, and a blower B is installed. By operating and performing aeration with air, the raw water introduction step and the aeration step are performed simultaneously.

  In this method, the ratio of raw water introduction process time (raw water introduction time) to aeration process time (aeration time) (raw water introduction time / percentage of aeration time) is 40 to 100%, especially 50 to 100%. It is preferable to control the raw water introduction time and the aeration time. That is, raw water introduction and aeration are started simultaneously, and when the water level in the reaction tank reaches a predetermined position, the raw water introduction and aeration may be terminated simultaneously to terminate the reaction (ratio of raw water introduction time / aeration time ratio). 100%), starting the introduction of raw water and aeration at the same time, and after introducing the raw water and aeration for a predetermined time, when the water level in the reaction tank reached a predetermined position, the introduction of the raw water was stopped, and then only aeration was further carried out The post reaction may be terminated.

  In this time control method, the introduction of raw water is stopped when the water level in the reaction tank 1 rises to a predetermined position using a water level sensor, a flow meter, a timer, etc. (not shown), and then further if necessary. After continuing the aeration, the aeration is stopped and the sludge settling process and the treated water discharging process are performed.

  In this control method as well as in the following control methods, it is preferable to ensure a sufficient aeration time (reaction time) in order to achieve a high nitrogen removal rate. Although depending on the amount, the aeration time is preferably 2 hours or longer, for example, 4 to 16 hours.

  In this case, when the pH of the liquid in the tank measured by the pH measuring device pH exceeds the preferred pH range (6.7 to 8.3), the pH is adjusted from the drug introduction path L2 by operating the pump P2. An agent (acid or alkali) may be added.

  FIG. 2 measures the pH of the liquid in the reaction tank 1 using the pH measurement device pH, and controls the raw water introduction process and the aeration process based on this pH measurement value. The introduction process and the aeration process are started at the same time, the pH of the liquid in the reaction tank 1 is measured, and the water level provided in the reaction tank 1 after the pH measurement value becomes 8.3 or less by the introduction and aeration of the raw water. When the sensor LS detects that the water level has reached a predetermined level, the introduction of raw water is stopped. At that time, when the measured pH value exceeds 8.3 by the control device 10 to which the measured pH value is input, the introduction of the raw water is temporarily stopped and only aeration is performed, and the pH is lowered to 8.3 or less by aeration. When it becomes, intermittent introduction to resume the introduction of raw water is performed until the water level reaches a predetermined level. After that, if necessary, the aeration is further continued, and then the aeration is stopped to complete the reaction, and a sludge precipitation step and a treated water discharge step are performed.

  In this way, by performing aeration concurrently with the introduction of raw water into the reaction tank, without adding chemicals for pH adjustment, or after significantly reducing the amount added compared to the conventional method In addition, it is possible to suppress the increase in pH of the liquid in the reaction tank when introducing raw water and control the pH range to be suitable for the ANAMOX reaction, thereby performing stable and efficient denitrification treatment.

  The present invention will be described more specifically with reference to the following examples.

[Example 1]
A synthetic wastewater having ammonia nitrogen: 900 mg / L, IC: 350 mg / L, pH: 9.0 was prepared. As the single tank type ANAMMOX reaction tank, a laboratory test apparatus having a reaction tank volume of 4 L was used. As the seed sludge, one-tank type AAMAMOX sludge cultured in synthetic waste water was added so that the sedimentation volume was 30% of the tank volume. The water temperature was 32 ° C. The amount of exchanged water per batch was 0.8 L, and the batch cycle was an aeration process 6 hr, a sludge precipitation process 3 min, and a treated water discharge process 10 min. The raw water introduction process was started simultaneously with the start of the aeration process, and the introduction time was 2.4 hr (40% of the aeration process). The results are shown in Table 1.

  In this example, although the pH of the liquid in the tank increased from the start of the raw water introduction, it remained at the maximum pH 8.2, and after the raw water introduction process was completed, ammonia nitrogen was removed by the one-tank type ANAMMOX reaction, The pH dropped slowly and reached pH 7.1 at the end of the reaction. The nitrogen removal rate at this time was 87%, and the treated water had an ammonia nitrogen concentration of 1 mg / L or less, a nitrite nitrogen concentration of 5.2 mg / L, and a nitrate nitrogen concentration of 113 mg / L. It was thought that ammoniacal nitrogen was removed by the type ANAMOX reaction.

[Comparative Example 1]
It implemented like Example 1 except not having aerated at the time of raw | natural water introduction. The results are shown in Table 1.

  In this comparative example, the pH of the liquid in the reaction tank rose to 9.0 in the raw water introduction process. Although the pH decreased gradually during the aeration process, the pH at the end of the aeration process was 8.4, which caused the activity of the ANAMMOX bacteria to decrease. The treated water had an ammonia nitrogen concentration of 88 mg-N / L, a nitrite nitrogen concentration of 279 mg / L, and a nitrate nitrogen concentration of 47 mg / L, and the nitrogen removal rate was 54%. In addition, nitrite nitrogen having a strong inhibitory effect on ANAMOX bacteria was accumulated in the reaction tank at a high concentration.

<Result>
When raw water pH is high, aeration at the time of raw water introduction prevents treatment failure due to inactivation or inhibition of ANAMMOX bacteria due to pH exceeding 8.3 during the aeration process, stably removing more than 80% of nitrogen Rate can be obtained.

[Examples 2-1 to 3 and Comparative Examples 2-1 to 3]
In Example 1, the conditions of the synthetic wastewater were changed to ammonia nitrogen: 1,800 mg / L, IC: 1,200 mg / L, pH: 9.0, and raw water introduction time was changed as shown in Table 2 The time / aeration time ratio was varied in the range of 10 to 100%.
The solution pH in the tank and the nitrogen removal rate during the aeration process (reaction process) at this time were as shown in Table 2.

As shown in Table 2, when the raw water introduction time / aeration time ratio was 10 to 30%, the nitrogen removal rate decreased to 34 to 67%.
When the IC in the raw water is high, the pH drop due to the reaction does not catch up with the pH increase due to the introduction of the raw water, and the pH of the liquid in the tank exceeds 8.3. It is estimated that 50 mg-N / L or more of nitrogen accumulated, and that the ANAMOX bacteria were inhibited by nitrite nitrogen.
On the other hand, when the raw water introduction time / aeration time ratio is 40% or more and raw water is introduced at a low flow rate, the pH of the liquid in the tank is stably 8.3 or less, and a high nitrogen removal rate of 80 to 89%. was gotten.

<Result>
When the raw water IC is high, the raw water is introduced at a low flow rate over time so that the raw water introduction time / aeration time ratio is 40% or more, so that the pH during the aeration process does not exceed 8.3, The inactivation and inhibition of the ANAMOX bacteria can be prevented, and a nitrogen removal rate of 80% or more can be stably obtained.

[Examples 3-1 to 3 and Comparative examples 3-1 to 3]
In Example 1, the conditions of the synthetic wastewater were changed to ammonia nitrogen: 1,800 mg / L, IC: 150 mg / L, pH: 10, and the raw water introduction time / aeration time ratio was changed as shown in Table 3 In the range of 10 to 100%.
The solution pH in the tank and the nitrogen removal rate during the aeration process (reaction process) at this time were as shown in Table 3.

As shown in Table 3, when the pH of the raw water was higher, the nitrogen removal rate was 28% or less when the raw water introduction time / aeration time ratio was 10 to 30%. In particular, when the content is 10 to 20%, the pH of the liquid in the tank during the aeration process exceeded 9, and it is estimated that the activity of nitrifying bacteria in addition to the ANAMOX bacteria was reduced. Note that ammonia stripping occurred due to the high pH, and it was difficult to measure the nitrogen removal rate by biological treatment.
On the other hand, when the raw water introduction time / aeration time ratio is 40% or more and raw water is introduced at a low flow rate, the pH of the liquid in the tank is stably 8.3 or less, and a high nitrogen removal rate of 80 to 89%. was gotten.

<Result>
When the raw water pH is higher, the raw water is introduced at a low flow rate over time so that the raw water introduction time / aeration time ratio is 40% or more, so that the pH at the initial stage of the aeration process does not exceed 8.3. Further, volatilization due to ammonia stripping and inactivation of ANAMXOX bacteria can be prevented, and a nitrogen removal rate of 80% or more can be stably obtained.

DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Mixed sludge 3 Reaction liquid 4 Air diffuser L1 Raw water introduction path L2 Chemical | medical agent introduction path L3 Treated water extraction path L4 Air introduction path 10 Control apparatus

Claims (8)

  A method of batch-type denitrification using ammonia nitrogen-containing wastewater as raw water and a reaction vessel containing mixed sludge of ammonia-oxidizing bacteria and ANAMMOX bacteria, wherein the aeration step is performed in the raw water introduction step to the reaction vessel A method for denitrifying wastewater containing ammonia nitrogen, which is performed simultaneously.   2. The ratio (raw water introduction time / percentage of aeration time) of the time of the raw water introduction process (hereinafter referred to as “raw water introduction time”) and the time of the aeration process (hereinafter referred to as “aeration time”) is 40. A denitrification method for ammonia nitrogen-containing wastewater, characterized in that the content is -100%.   The method for denitrifying ammonia nitrogen-containing wastewater according to claim 1, wherein the pH in the reaction vessel is measured, and when the measured pH value exceeds 8.3, the introduction of the raw water is stopped. .   The denitrification method for ammonia nitrogen-containing wastewater according to any one of claims 1 to 3, wherein the pH of the raw water exceeds 8.3 and is 10 or less.   5. The denitrification method for ammonia nitrogen-containing wastewater according to claim 1, wherein the raw water has an inorganic carbonic acid concentration of 150 to 3,000 mg / L.   6. The denitrification method for ammonia nitrogen-containing wastewater according to any one of claims 1 to 5, wherein the raw water is a dehydrated filtrate of anaerobic digestive juice. A denitrification apparatus for performing the denitrification method of ammonia nitrogen-containing wastewater according to claim 1, 2, 5, or 6,
A reaction vessel containing mixed sludge of ammonia-oxidizing bacteria and ANAMOX bacteria;
Raw water introduction means for introducing ammoniacal nitrogen-containing wastewater into the reaction tank as raw water;
Treated water discharge means for discharging denitrified treated water from the reaction tank;
Aeration means for aeration of the reaction solution in the reaction tank;
A batch one-tank type ANAMMOX reactor having an operation of the raw water introduction means and a control means for controlling the operation of the aeration means,
The denitrification apparatus for ammonia nitrogen-containing wastewater, wherein the control means is a means for performing control to aerate the inside of the reaction tank by the aeration means when the raw water is introduced by the raw water introduction means. A denitrification apparatus for performing the denitrification method for ammonia nitrogen-containing wastewater according to claim 3 or 4,
A reaction vessel containing mixed sludge of ammonia-oxidizing bacteria and ANAMOX bacteria;
Raw water introduction means for introducing ammoniacal nitrogen-containing wastewater into the reaction tank as raw water;
Treated water discharge means for discharging denitrified treated water from the reaction tank;
Aeration means for aeration of the reaction solution in the reaction tank;
PH measuring means for measuring the pH of the liquid in the reaction vessel;
A batch one-tank type ANAMMOX reactor having an operation of the raw water introduction means and a control means for controlling the operation of the aeration means,
When the raw water is introduced by the raw water introducing means, the control means is configured to aerate the inside of the reaction tank by the aeration means, and when the measured value of the pH measuring means exceeds 8.3, the raw water introducing means A denitrification treatment apparatus for ammonia-containing nitrogen-containing wastewater, characterized by performing control to stop the introduction of raw water.

Images