KR20160150287A - Method of partial nitrification using aerobic granular sludge - Google Patents

Abstract

Provided is a partial nitrification method using aerobic granular sludge. The partial nitrification method using aerobic granular sludge comprises the following steps: preparing the aerobic granular sludge in a reaction tank; introducing ammonia-containing treating water into the reaction tank; and aerating the treating water so as to oxidize ammonia contained in the treating water into nitrous acid using the aerobic granular sludge in the reaction tank.

Description

[0001] The present invention relates to a partial nitrification method using aerobic granular sludge,

The present invention relates to a partial nitrification method using aerobic granular sludge and more particularly to a partial nitrification method using aerobic granular sludge which comprises oxidizing ammonia contained in treated water with nitrite using aerobic granular sludge .

Recently, many technologies for removing nitrogen, which is the cause of eutrophication, have been developed. Biological nitrification and denitrification processes are currently the most widely used processes for nitrogen removal.

When nitrification and denitrification processes are performed using activated sludge, operational problems such as sludge bulking and sludge rinsing may occur. In addition, it is difficult to operate and maintain the reaction system because the bacteria are susceptible to environmental conditions and slow in growth rate.

Korean Patent Application Laid-Open No. 10-2002-0090967 (Application No. 10-2002-0065480, filed by KAIST, etc.), an anaerobic / anaerobic process is alternately repeated by intermittent operation of an internal circulation pump, Discloses a membrane separation activated sludge process which removes nitrogen and releases phosphorus in an anaerobic state to effectively treat nitrogen and phosphorus in the treated water and treated water at the same time.

Korean Unexamined Patent Application Publication No. 10-2002-0090967

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable partial nitrification method.

Another technical problem to be solved by the present invention is to provide a highly efficient partial nitrification method.

Another technical problem to be solved by the present invention is to provide a partial nitrification method with reduced oxygen demand in the nitrification process.

It is another object of the present invention to provide a partial nitrification method in which the amount of organic matter required in the nitrification process is reduced.

The technical problem to be solved by the present invention is not limited to the above.

In order to solve the above technical problems, the present invention provides a partial nitrification method using aerated granular sludge.

According to one embodiment, the partial nitrification method using the aerated granular sludge may include the steps of preparing aerated granular sludge in a reaction tank, introducing treatment water containing ammonia into the reaction tank, and aerating the treated water, , The step of oxidizing ammonia contained in the treated water with nitrite by the aerobic granular sludge may be included.

According to one embodiment, the ammonia oxidizing bacteria may comprise a dominant (dominant) component than the nitrite oxidizing bacteria.

According to an embodiment, the partial nitrification method using the aerated granular sludge may include the steps of injecting organic matter into the reaction tank, and reducing nitrite to nitrogen gas by the aerobic granular sludge and organic matter in the reaction tank .

According to one embodiment, the step of oxidizing the ammonia to nitrite is performed at the surface of the aerobic granular sludge, and the step of reducing the nitrite to nitrogen may include being performed in the aerobic granular sludge .

According to one embodiment, the surface of the aerated granular sludge may be an aerobic condition and the interior of the aerobic granular sludge may be an anaerobic condition.

According to one embodiment, the reaction vessel may comprise a continuous batch reactor.

According to one embodiment, the ammonia may be oxidized to nitrite to reduce the size of the aerated particulate sludge.

According to the embodiment of the present invention, aerobic granular sludge is generated in the reaction tank, and ammonia contained in the treated water can be oxidized to nitrite using the aerobic granular sludge in the reaction tank. Thereby, a highly efficient partial nitrification method with reduced oxygen demand and organic matter requirement can be provided.

In addition, the production of the aerobic granular sludge and the nitrite oxidation of ammonia can be performed in the same reaction tank, and a simplified process for partial nitrification of the process can be provided.

1 is a photograph of a aerated granular sludge used in a partial nitrification method using aerobic granular sludge according to an embodiment of the present invention.
FIG. 2 is a graph showing partial nitrification results by a partial nitrification method using aerobic granular sludge according to an embodiment of the present invention.
FIG. 3 is a view showing the microbial genus of the aerated granular sludge used in the partial nitrification method using the aerated granular sludge according to the embodiment of the present invention.
4 is a graph showing the nitrogen concentration of partially treated nitrified water according to an embodiment of the present invention.
5 is a graph of Alkalinity and pH of partially treated nitrified water according to an embodiment of the present invention.
6 is a graph illustrating nitrification rate and nitrification rate of partially nitrified treated water according to an embodiment of the present invention.
7 is an FE-SEM photograph of aerated granular sludge of partially nitrified treated water according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical spirit of the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Also, while the terms first, second, third, etc. in the various embodiments of the present disclosure are used to describe various components, these components should not be limited by these terms. These terms have only been used to distinguish one component from another. Thus, what is referred to as a first component in any one embodiment may be referred to as a second component in another embodiment. Each embodiment described and exemplified herein also includes its complementary embodiment. Also, in this specification, 'and / or' are used to include at least one of the front and rear components.

The singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It is also to be understood that the terms such as " comprises "or" having "are intended to specify the presence of stated features, integers, Should not be understood to exclude the presence or addition of one or more other elements, elements, or combinations thereof.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

A partial nitrification method using aerated granular sludge according to an embodiment of the present invention is described.

Aerobic granular sludge can be prepared in the reaction tank. According to one embodiment, the reaction vessel may be a continuous batch reaction vessel. According to one embodiment, the aerated granular sludge may be one that has been cultivated in the semi-ounce (e. G., A continuous batch reactor).

Treated water containing ammonia may be introduced into the reaction tank. The treated water may be a high concentration ammonia waste water of 800 mg NH ₄ -N / L or more.

Organic matter may be injected into the reaction tank before the treated water flows into the reaction tank or after the treated water has flowed into the reaction tank. For example, the organic material may be, for methanol (CH ₃ OH).

Oxygen can be supplied in the reaction tank to aerate the treated water. Therefore, in the reaction tank, ammonia (NH ₄ ⁺ ) contained in the treated water can be oxidized to nitrite (NO ₂ ^- ) by the aerobic granular sludge. Ammonia reacts with oxygen supplied to the reaction tank and is oxidized to nitrite by the aerobic granular sludge as shown in the following Formula 1 to produce water and hydrogen ions.

≪ Formula 1 >

NH ₄ ⁺ + 1.5 O ₂ -> NO ₂ ^- + H ₂ O + 2H ⁺

The surface of the aerobic granular sludge may be aerobic condition by oxygen supplied into the reaction tank. Thus, the step of oxidizing ammonia to nitrite can be carried out on the surface of the aerobic granular sludge.

Also, according to one embodiment, the ammonia may be oxidized to nitrite at the surface of the aerobic granulated sludge, so that the size of the aerobic granulated sludge may be reduced.

The nitrite oxidized with ammonia contained in the treated water can be reduced to nitrogen gas by the aerobic granular sludge and the organic matter in the reaction tank. For example, nitrous acid can be reduced to nitrogen gas by reacting with the organic substance (for example, methanol) as shown below in Formula 2 below.

(2)

6NO ₂ ^- + 3CH ₃ OH + 3CO ₂ -> 3N ₂ + 6HCO ₃ ^- + 2H ⁺

The inside of the aerobic granular sludge may be anaerobic condition because oxygen supplied into the reaction tank is not transferred. Thus, the step of reducing the nitrous acid may be performed in the aerobic granular sludge.

While ammonia contained in the treated water is oxidized to nitrite and nitrite is reduced to nitrogen gas, Nitrosomas, which is an ammonia oxidizing bacteria that oxidizes ammonia to nitrite, may be dominant than nitrite bacteria which are nitrite oxidized by nitrite have. As a result, the nitrification rate of the ammonia contained in the treated water is higher than the nitrification rate, so that the ammonia contained in the treated water can be efficiently oxidized to nitrite. Accordingly, the oxygen demand amount and the organic matter demand amount necessary for removing the nitrogen contained in the treated water can be reduced.

If the ammonia contained in the treated water is oxidized to nitric acid as shown in the following chemical formula 3 and nitric acid is reduced to nitrogen gas as shown in the following chemical formula 4, Can be increased.

(3)

NH ₄ ⁺ + 2O ₂ -> NO ₃ ^- + H ₂ O + 2H ⁺

≪ Formula 4 >

6NO ₂ ^- + 5CH ₃ OH + CO ₂ -> 3N ₂ + 6HCO ₃ ^- + 2H ⁺

However, as described above, according to the embodiment of the present invention, when ammonia contained in the treated water is oxidized to nitrite using the aerobic granular sludge and nitrite is reduced to nitrogen gas, ammonia contained in the treated water is reduced Compared to oxidizing with nitric acid and reducing nitric acid to nitrogen gas, the oxygen demand can be reduced by 25% and the organic matter requirement can be reduced by 40%. Thereby, a method of removing nitrogen from treated water with reduced oxygen demand and organic matter demand can be provided.

Further, in the reaction tank in which the aerated granular sludge is cultivated, a partial nitrification process is performed in which the ammonia contained in the treated water is oxidized with nitrite, so that the process can be simplified.

Hereinafter, a specific experimental example of the partial nitrification method using the aerated granular sludge according to the above-described embodiment of the present invention will be described.

According to the embodiment of the present invention described above, the aerobic granular continuous batch reactor was operated under the operating conditions shown in Table 1 below. The effective volume of the reactor was 2.85 L, and the partial nitrification, in which the ammonia contained in the treated water was oxidized to nitrite, was operated for 130 days while increasing the ammonium concentration.

Driving factor Operation value Inoculated sludge Aerobic granular sludge Initial sludge concentration 3000 mg / L Inlet (NH ₄ ) ₂ SO ₄ Concentration 200-800 mg NH ₄ -N / L Alkalinity 3500-4000 mg CaCO ₃ / L Temperature 35? pH 7.5 to 8.5 Dissolved oxygen 2mg / L or more Aeration intensity 3L / min Inflow time 4 minutes Aeration time 350 minutes Settling time 5 minutes Leak time 1 minute Hydraulic residence time (HRT) 0.48 days

1 is a photograph of a aerated granular sludge used in a partial nitrification method using aerobic granular sludge according to an embodiment of the present invention.

Referring to FIG. 1, ammonia contained in treated water was oxidized with nitrous acid using aerobic granular sludge under the same conditions as in the above-mentioned <Table 1>, and aerobic granular sludge was photographed.

Fig. 1 (a) shows the aerated granular sludge inoculated, and Fig. 1 (b) shows aerated granular sludge after the ammonia contained in the treated water was oxidized with nitrite. As can be seen from Fig. 1, it can be seen that the inoculated aerated granular sludge having an average diameter of 6 mm was reduced to an average diameter of 1 mm. It can also be confirmed that the inoculated aerobic granular sludge retains the granular sludge even after the ammonia contained in the treated water is oxidized with nitrite.

FIG. 2 is a graph showing partial nitrification results by a partial nitrification method using aerobic granular sludge according to an embodiment of the present invention.

Referring to FIG. 2, ammonia, nitrite, nitric acid, and alkalinity were measured in the process of oxidizing ammonia contained in treated water to nitrite using aerobic granular sludge under the same conditions as in Table 1 will be.

After 20 days of reactor operation, it can be observed that the nitrite begins to accumulate. Furthermore, even after increasing the loading ammonia load to 1.79 kg N / m ² / d, it can be confirmed that the microorganisms are not inhibited by the toxicity of ammonia and the ammonia is oxidized with nitrous acid.

FIG. 3 is a view showing the microbial genus of the aerated granular sludge used in the partial nitrification method using the aerated granular sludge according to the embodiment of the present invention.

3, ammonia contained in the treated water was oxidized with nitrite using aerobic granular sludge under the same condition as in the above-mentioned <Table 1>, and the microbial community analysis of the granular sludge was performed. Respectively.

As can be seen from FIG. 3, it can be seen that Nitrosomas, an ammonium oxidizing bacteria that oxidizes ammonia to produce nitrite, dominated nitrite, which is a nitrite-oxidizing nitric acid, by oxidizing nitrite.

Unlike the operating conditions in Table 1, ammonia contained in the treated water was oxidized to nitrite using the granular sludge cultured with glucose as a carbon source in a continuous batch reactor under the operating conditions shown in Table 2 below Partial nitrification was performed.

Driving factor Operation value Influent flow 1.5 L Inflow time 3 minutes Aeration time 325 minutes Settling time 30 minutes Leak time 2 minutes Hydraulic residence time (HRT) 6 hours

Stage A was defined as the stage A until 37 days after the start of the reaction under the operating conditions shown in Table 2, and the ammonia concentration of the treated water was set to 250 mg / L and the alkalinity (CaCo ₃ ) was set to 3000 mg / L. In addition, 38 to 61 days were defined as stage B, ammonia concentration of 500 mg / L was introduced, and Alkalinity (CaCo ₃ ) was set at 4800 mg / L. 61 to 88 days were defined as stage C, and treated water with an ammonia concentration of 700 mg / L was introduced and Alkalinity (CaCo ₃ ) was set to 3500 mg / L.

FIG. 4 is a graph of nitrogen concentration of partially nitrified treated water according to an embodiment of the present invention, FIG. 5 is a graph of Alkalinity and pH of treated nitrified water according to an embodiment of the present invention, 6 is a graph showing nitrification rate and nitrification rate of partially nitrified treated water according to an embodiment of the present invention, and FIG. 7 is an FE-SEM photograph of aerated granular sludge of partially nitrified treated water according to an embodiment of the present invention.

Referring to FIGS. 4 to 7, ammonia contained in the treated water was oxidized to nitrite using aerobic granular sludge under the same conditions as in Table 1 described above.

As can be seen from Fig. 4, 13 days after the start of the reaction, ammonia was oxidized to nitrite. Thereafter, the concentration of NO ₂ -N continuously increased, but the concentration of NO ₃ -N did not substantially change. Nitrate accumulation was observed after 15 days after the concentration of the treated water including ammonia was increased, and nitrification phenomenon was not observed substantially.

As can be seen in FIGS. 5 and 6, the alkaline concentration of the initial treated water was reduced to 1000 mg / L after 30 days of reaction time. As a result of the decrease in alkalinity, it can be seen that the autotrophic bacteria grew by adaptation, and the nitrification rate was remarkably higher than the nitrification rate by more than 70%, confirming the growth of ammonium oxidizing bacteria in the autotrophic bacteria .

As can be seen from FIG. 7, the average diameter of the aerobic granulated sludge at the beginning of the reaction was about 3 mm, while the average diameter was observed to be about 1 mm after 30 days and 60 days. In addition, FE-SEM photographs show that microorganism species change with time according to environmental conditions. Therefore, even if the aerobic granular sludge that initially cultivated with glucose as a carbon source reacts with the treated water containing high concentration ammonia, the granular form is not disassembled and the morphology changes according to the environment, and at the same time, the microorganism species can be observed.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. It will also be appreciated that many modifications and variations will be apparent to those skilled in the art without departing from the scope of the invention.

Claims (5)

Preparing aerobic granular sludge in the reaction tank;
Introducing treatment water containing ammonia into the reaction tank;
A step of aerating the treated water and oxidizing ammonia contained in the treated water by the aerated granular sludge in the reaction tank with nitrite as shown in Formula 1;
Injecting methanol (CH ₃ OH) into the reaction tank after the treated water flows into the reaction tank; And
And reducing nitrite to nitrogen gas by the aerobic granular sludge and methanol in the reaction tank,
Wherein the ammonia oxidizing bacteria have dominance over the nitrite oxidizing bacteria and the nitrification rate of the ammonia contained in the treated water is higher than the nitrification rate.
&Lt; Formula 1 >
NH ₄ ⁺ + 1.5 O ₂ -> NO ₂ ^- + H ₂ O + 2H ⁺
(2)
6NO ₂ ^- + 3CH ₃ OH + 3CO ₂ -> 3N ₂ + 6HCO ₃ ^- + 2H ⁺
The method according to claim 1,
The step of oxidizing the ammonia with nitrite is carried out on the surface of the aerobic granular sludge,
Wherein the step of reducing the nitrite to nitrogen is performed in the aerobic granulated sludge.
3. The method of claim 2,
Wherein the surface of the aerated granular sludge is in an aerobic condition,
Wherein the inside of the aerated granulated sludge is anaerobic.
The method according to claim 1,
Wherein the reaction tank comprises a continuous batch reactor, and the partial nitrification method using aerated granular sludge.
The method according to claim 1,
Wherein the ammonia is oxidized to nitrite to reduce the size of the aerobic granulated sludge.

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