KR20160140550A - Method for treating wastewater - Google Patents

Abstract

Provided are a wastewater treatment apparatus and a method thereof. The wastewater treatment method comprises the following steps: introducing wastewater containing ammonia nitrogen; aerating by supplying air into the wastewater; regulating a solids retention time (SRT) by discharging the wastewater; precipitating the wastewater; and regulating a hydraulic retention time (HRT). According to the present invention, the wastewater treatment method enables the formation of nitrite nitrogen through a nitritation reaction using ammonia nitrogen.

Description

METHOD FOR TREATING WASTEWATER [0002]

The present invention relates to a wastewater treatment method.

As the population grows, the amount of pollutants emitted is also increasing. Since these pollutants not only destroy the environment but also cause various infectious diseases, technologies for treating pollutants in developed countries have been attracting attention. Particularly, nutrients, which are one of the pollutants, are mainly composed of phosphorus emitted from industrial products such as nitrogen and pesticide discharged from sewage and livestock manure. When they are mixed with rivers, they cause eutrophication and adversely affect the aquatic ecosystem. Generally, nutrients have a large amount of nitrogen derived from wastewater. In order to remove such nitrogen, a waste water treatment technology in which denitrification technology is fused is needed.

In order to remove nitrogen from the sewage treatment plant, a physicochemical method of removing nitrogen by injecting a drug and a biological nitrogen removal process using microorganisms are mainly used. In the case of the physico-chemical method, secondary water pollution due to injected chemicals may occur, and in recent years, there is a tendency to use a biological nitrogen removal process. Biological nitrogen removal processes can convert nitrogen components in sewage or wastewater into nitrogen gas based on oxidation-reduction reactions of microorganisms. This process is also carried out through a nitrification process under aerobic conditions and a denitrification process under anaerobic conditions. In the nitrification process, the ammonia nitrogen present in the water is oxidized to nitrate nitrogen, and in the denitrification process, nitrogen in the water can be removed by reducing nitrate nitrogen to nitrogen gas.

On the other hand, Sequencing Batch Reactor (SBR) is widely used as a device for removing biological nitrogen, and it can discharge treated water with a small amount of electric power compared to other devices. However, the conventional continuous batch-type reaction process requires a large amount of oxygen in the process of oxidizing ammonia nitrogen to nitrate nitrogen, and it is difficult to supply a large amount of the oxygen. Further, there is a problem that sludge is generated as carbon sources are consumed during nitrification and denitrification, and additional cost for treating such sludge is consumed. In addition, the existing continuous batch processing process has a problem that it is difficult to arbitrarily control the reaction for nitrogen removal by simultaneously controlling the hydraulic retention time (HRT) and the solid retention time (SRT).

In order to solve the above problems, the present invention provides a wastewater treatment method capable of reducing operating cost due to low oxygen consumption and carbon consumption.

The present invention provides a wastewater treatment method capable of controlling the nitrification reaction.

The present invention provides a wastewater treatment apparatus to which the wastewater treatment method can be applied.

Other objects of the present invention will become apparent from the following detailed description and the accompanying drawings.

The method of treating wastewater according to embodiments of the present invention includes the steps of introducing wastewater containing ammonia nitrogen, supplying air to the wastewater, solidus retention time (SRT) , Adjusting the hydraulic retention time (HRT), and adjusting the nitrite nitrogen through the nitrification reaction of the ammonia nitrogen to form nitrite nitrogen .

The nitrification ratio of the ammonia nitrogen may be 70 to 100%.

The solids retention time can be adjusted from 1 to 10 days (Day).

The hydraulic retention time can be adjusted to 0.5 to 10 days (Day).

And forming a nitrogen gas through the nitrification reaction of the nitrite nitrogen.

The nitrogen gas forming step comprises mixing the wastewater containing the nitrite nitrogen and the wastewater containing the ammonia nitrogen at a ratio of 1: 1 to 2: 1, and a step of mixing the nitrite nitrogen and the ammonia nitrogen And forming the nitrogen gas through the reaction.

The apparatus for treating wastewater according to embodiments of the present invention includes a continuous batch reactor in which nitrite nitrogen is formed by performing a nitrification reaction on wastewater containing ammonia nitrogen, And an outlet including a main body capable of containing wastewater containing nitrogen, an aeration unit for supplying air to the wastewater, and at least one valve capable of moving the wastewater to the outside of the main body, The batch reactor is characterized in that the solids retention time (SRT) and the hydraulic retention time (HRT) are separately controlled.

The solids retention time can be adjusted from 1 to 10 days (Day).

The hydraulic retention time can be adjusted to 0.5 to 10 days (Day).

And an anammox reaction device for forming nitrogen gas through the nitrification reaction of the nitrite nitrogen and the ammonia nitrogen.

The wastewater treatment method according to the embodiments of the present invention induces a nitrification reaction of ammonia nitrogen, thereby reducing oxygen consumption and carbon consumption. The wastewater treatment method can separate and regulate the solids retention time and the hydraulic retention time to induce an effective nitrification reaction, thereby resulting in a high nitrogen removal efficiency. In addition, the above-mentioned wastewater treatment method can remove nitrogen of high concentration contained in the reflux water with high efficiency.

The wastewater treatment apparatus according to the embodiments of the present invention can separate and regulate the solids retention time and the hydraulic retention time to induce an effective nitrification reaction and thereby have a high nitrogen removal efficiency. In addition, the wastewater treatment apparatus can remove nitrogen of high concentration contained in the reflux water with high efficiency.

1 shows a method of treating wastewater according to embodiments of the present invention.
2 shows a method of forming nitrite nitrogen according to embodiments of the present invention.
3 shows a wastewater treatment apparatus according to embodiments of the present invention.
4 shows a wastewater treatment apparatus according to embodiments of the present invention.
5 shows a continuous batch reactor according to embodiments of the present invention.
Figure 6 shows a continuous batch reactor in the inflow stage according to embodiments of the present invention.
Fig. 7 shows a continuous batch reactor in the case of the aeration step according to the embodiments of the present invention.
FIG. 8 shows a continuous batch reactor in the SRT adjustment step according to the embodiments of the present invention.
Figure 9 shows a continuous batch reactor in the settling step according to the embodiments of the present invention.
FIG. 10 shows a continuous batch reactor in the HRT regulating step according to the embodiments of the present invention.
11 shows the operation result of the continuous batch reactor according to the embodiments of the present invention.

Hereinafter, the present invention will be described in detail with reference to examples. The objects, features and advantages of the present invention will be easily understood by the following embodiments. The present invention is not limited to the embodiments described herein, but may be embodied in other forms. The embodiments disclosed herein are provided so that the disclosure may be thorough and complete, and that those skilled in the art will be able to convey the spirit of the invention to those skilled in the art. Therefore, the present invention should not be limited by the following examples.

As a method for removing nitrogen contained in wastewater, nitrate nitrogen is produced through nitrification reaction of ammonia nitrogen, and nitrogen gas is produced through denitrification of nitrate nitrogen. The following reaction formula (1) indicates a nitrification reaction, and the reaction formula (2) indicates a denitration reaction. Referring to equations (1) and (2), the nitrification reaction and the denitrification require a large amount of oxygen, and a large amount of sludge is discharged during the process of consuming carbon.

The nitrification reaction and the denitrification are reactions in which the ammonia nitrogen is converted into the nitrite nitrogen before the conversion to the nitrate nitrogen, followed by denitrification. Reaction formula (3) below represents the nitrification reaction and Reaction formula (4) represents the denitration reaction. Referring to Equation (3) and Equation (4), the nitrification reaction can reduce the oxygen content by 25% compared to the nitrification reaction, and the denitrification reaction can produce 40% Saving effect.

Although the nitrification reaction is less likely to be induced than the nitrification reaction, the nitrification reaction can be induced with high efficiency by using the wastewater treatment apparatus and / or method according to the embodiments of the present invention.

1 shows a method of treating wastewater according to embodiments of the present invention. Referring to FIG. 1, the wastewater treatment method includes the steps of (S10) forming a nitrite nitrogen by nitrification of wastewater containing ammonia nitrogen, and a step of adding wastewater containing nitrite nitrogen and the ammonia nitrogen Wherein the step of forming the nitrite nitrogen comprises the steps of: mixing solid wastewater and solid wastewater, and performing a denitration reaction to form nitrogen gas, retention time, HRT) can be adjusted differently.

In the nitrogen gas formation step (S20), the nitrite nitrogen may form nitrogen gas through the denitration reaction. Mixing the wastewater containing nitrite nitrogen and the wastewater containing ammonia nitrogen at a ratio of 1: 1 to 2: 1, and mixing the nitrite nitrogen and the ammonia nitrogen with the nitrogen gas through an anammox reaction To form a second layer.

Figure 2 shows a method (S10) of nitrite nitrogen formation according to embodiments of the present invention. Referring to FIG. 2, the nitrite nitrogen forming method (S10) includes a step (S11) of introducing the ammonia nitrogen-containing wastewater, a releasing step (S12) of supplying air to the wastewater containing the ammonia nitrogen, (S13) of discharging the wastewater to control the solids retention time (S13), separating the wastewater remaining after the outflow into a solid and a supernatant (S14), and discharging the supernatant to distill the hydraulic retention time (S15). ≪ / RTI >

The wastewater containing the ammonia nitrogen is introduced (S11). The wastewater may be a reflux water. The reflux water may include an anaerobic digestion supernatant, a concentrated supernatant, a desalination solution, and the like. The concentration range of the ammonia nitrogen may be 220 mg / L to 300 mg / L. Preferably, the concentration range of the ammonia nitrogen may be an average of 260 mg / L. The alkalinity required for pre-entry nitrification can be supplemented, and the alkalinity / ammonia nitrogen ratio can be adjusted to 7.1 to 7.2.

Air is supplied to the wastewater containing the ammonia nitrogen (S12). The air is oxygen-enriched air, which can promote the activity of aerobic ammonia decomposing microorganisms.

The wastewater flows out to adjust the solids retention time (S13). The wastewater may contain the ammonia nitrogen and the nitrite nitrogen produced by the activity of the microorganism. By controlling the solids retention time before the wastewater is settled, the microorganisms can be prevented from changing the nitrite nitrogen to nitrate nitrogen. The solids retention time can be adjusted to 1 to 10 days (Day), but is not limited thereto and may be varied depending on the type of the wastewater. For example, the solids retention time can be adjusted to 1 to 2 days. In order to control the solids retention time, the wastewater may flow 10 to 90% of the total volume, but the present invention is not limited thereto. The effluent may vary depending on conditions such as the temperature of the wastewater. Preferably, the wastewater can be drained by 50% of the total volume.

The wastewater remaining after the outflow is precipitated and separated into a solid and a supernatant (S14). The wastewater remaining after the outflow may contain a large amount of the ammonia nitrogen. Through the precipitation, the ammoniacal nitrogen may be formed of the nitrite nitrogen.

The supernatant is flowed out to adjust the hydraulic retention time (S15). The supernatant may contain a large amount of the nitrite nitrogen. The hydraulic retention time may be adjusted to 0.5 to 10 days (Day), but is not limited thereto and may vary depending on the inflow amount of the wastewater and / or the solids retention time. For example, the hydraulic residence time may be adjusted to 0.5 to 1 day.

Since the solids retention time adjustment (S13) and the hydraulic retention time adjustment (S15) can be performed separately, the nitrification reaction can be artificially induced. The sub-nitrification ratio of the ammonia nitrogen contained in the wastewater may be 70 to 100%.

FIG. 3 and FIG. 4 show a wastewater treatment apparatus according to embodiments of the present invention, and FIG. 5 shows a continuous batch reactor apparatus 100 according to embodiments of the present invention. 3, 4 and 5, the wastewater treatment apparatus includes a continuous batch reactor 100 for performing a nitrification reaction on wastewater containing ammonia nitrogen to form nitrite nitrogen, and a nitrite- An ammonia reaction apparatus 200 for mixing wastewater containing nitrogen gas and wastewater containing ammonia nitrogen, and performing an denitration reaction to form nitrogen gas. The continuous batch reactor 100 can separate and adjust the solid retention time (SRT) and the hydraulic retention time (HRT). The nitrification reaction can be freely controlled by controlling the solids retention time and the hydraulic retention time.

For example, in the wastewater reservoir 108 in which the concentration of ammonia nitrogen (NH ₄ + -N) is 100 mg / L as much as 1 Q, the wastewater containing 0.5 Q of ammonia nitrogen, May be introduced into the batch reactor (100). At this time, R3, which is the wastewater containing the remaining 0.5 Q of the ammonia nitrogen, may be introduced into the Anamos reaction apparatus 200. The 0.5 W wastewater flowing into the continuous batch reactor 100 may be R2 wastewater having the nitrite nitrogen (NO ₂ -N) concentration of 100 mg / L through the nitrification reaction. If the R 2 and R 3 wastewater flow into the anammox reactor 200, the ratio of the ammonia nitrogen to the nitrate nitrogen may be 1: 1, and the denitrification may occur to form the nitrogen gas have.

The continuous batch reactor apparatus 100 includes a main body 101, an aerator 102, a stirring unit 103, a measuring unit 104, an outlet 105, an inlet 106, a pump 107, A wastewater storage unit 108, and a control unit 110.

The main body 101 can receive the wastewater containing the ammonia nitrogen. The main body 101 may have a cylindrical shape or a hexagonal shape, but the present invention is not limited to this, and it suffices to accommodate the wastewater. The aeration unit 102 and the agitation unit 103 may be formed inside the body 101. Fig. The outflow portion 105 and the inflow portion 106 may be formed on the side surface of the main body portion 101. [

The aeration unit 102 can supply air to the wastewater. Preferably, the aeration unit 102 is located on the bottom surface or the bottom surface of the main body 101 and can supply air to the wastewater. The aeration unit 102 may be controlled by the control unit 110.

The agitating portion 103 can mix the wastewater. Preferably, the agitating portion 103 may include one or more blades. The stirring part 103 may be inserted into the body part 101 up to a height not touching the bottom surface of the body part 101. [

The outflow section 105 may include one or more valves capable of moving the wastewater out of the body section. The outflow portion 105 may be formed at one or more than one-quarter of the height of the bottom surface of the main body portion 101, but it may be a point at which the sludge formed at the bottom of the main body portion 101 does not flow out. Preferably, one or more outflow portions 105 may be formed on the bottom surface of the body portion 101 at one-third height or more. For example, the outflow section 105 can be formed at the ⅔ height point 105a, the ½ height point 105b, and the ⅓ height point 105c at the bottom surface of the main body 101 have. The shape of the valve is not limited, and the outlet 105 may be opened and closed.

The solids retention time may be adjusted to 1 to 10 days (Day), but is not limited thereto and may be varied depending on the kind and / or concentration of nitrogen contained in the wastewater. For example, the solids retention time can be adjusted to 1 to 2 days. In order to control the solids retention time, the wastewater may flow 10 to 90% of the total volume, but the present invention is not limited thereto. The effluent may vary depending on conditions such as the temperature of the wastewater. Preferably, the wastewater can be drained by 50% of the total volume.

The hydraulic retention time may be adjusted to 0.5 to 10 days (Day), but is not limited thereto and may vary depending on the inflow amount of the wastewater and / or the solids retention time. For example, the hydraulic residence time may be adjusted to 0.5 to 1 day.

The controller 110 may separately control the solids residence time and the hydraulic residence time. The control unit 110 selects one of the aeration unit 102, the agitation unit 103, the measurement unit 104, the outflow unit 105, the inflow unit 106, the pump 107, and the Anammox reaction unit 200 You can control more than one. The controller 110 may include a programmable logic controller (PLC).

The anammox reactor 200 may mix the wastewater containing the nitrite nitrogen and the wastewater containing the ammonia nitrogen and perform the denitrification to form nitrogen gas. The Anammox reaction apparatus 200 is a system in which wastewater containing the nitrite nitrogen and wastewater containing the ammonia nitrogen are mixed at a ratio of 1: 1 to 2: 1, and the nitrite nitrogen and the ammonia nitrogen are introduced into the ammonia- The nitrogen gas may be formed through the reaction.

FIG. 6 shows a continuous batch reactor apparatus 100 in the inflow step S11 according to the embodiments of the present invention. Referring to FIG. 6, in the step S11 of introducing the ammonia nitrogen-containing wastewater, the wastewater flows into the main body 101 while the inlet 106 is opened. At this time, the outflow section 105 is in a closed state. The pump 107 can be operated so that the wastewater can be continuously introduced from the wastewater storage unit 108. The measuring unit 104 measures the level of the wastewater in the main body 10 and can determine whether the wastewater should be further inflowed or stopped in the control unit 110 according to the level.

FIG. 7 shows a continuous batch reactor 100 in the case of the aeration step S12 according to the embodiments of the present invention. Referring to Fig. 7, in the aeration step S12 of supplying air to the wastewater, the inflow portion 106 is closed and the wastewater can be received in the main body portion 101. Fig. The stirring portion 103 mixes the wastewater, and the aeration portion 102 can supply air to the wastewater. At this time, the nitrification of the ammonia nitrogen contained in the wastewater can be performed by the microorganism.

FIG. 8 shows a continuous batch reactor 100 in the SRT adjustment step (S13) according to the embodiments of the present invention. Referring to FIG. 8, in the step of adjusting the solids retention time (S13), the outflow portion 105a located at the top of the outflow portion 105 may be opened to allow the solid matter to flow out. At this time, the outlet 105a may serve as the solids residence time control valve. The solids can be drained with the liquid portion of the wastewater, so that the hydraulic residence time can also be controlled.

FIG. 9 shows a continuous batch reactor 100 in the settling step (S14) according to the embodiments of the present invention. 9, in the step S14 of separating the wastewater remaining after the outflow into the solid matter and the supernatant liquid, the outflow portion 105 is closed, and the aeration portion 102 and the agitation portion 103 are also stopped Thereby helping the precipitation.

10 shows a continuous batch reactor 100 in the HRT regulating step S15 according to the embodiments of the present invention. Referring to FIG. 10, in the step of controlling the hydraulic retention time by discharging the supernatant liquid, the supernatant liquid may be discharged while the outflow portion 105b is opened. At this time, the solid matter may be precipitated as sludge and remain in the main body 101.

< Example >

In the present embodiment, the continuous batch reactor 100 uses the cylindrical acrylic to manufacture the main body 101, but the model and material of the main body 101 are not limited. A water jacket is placed outside the main body 101 and the temperature inside the main body 101 is adjusted to 30 to 40 占 폚 by placing a water jacket in the main body 101 Respectively. The control unit 110 uses a programmable logic controller (PLC) to perform the influx S11, the abandonment S12, the settlement S14, and the outflow S13 and S15. (S13) and sedimentation (S14) for regulating the solids retention time in the aeration step (S12), which is a completely mixed type for the separate processes of the solids retention time and the hydraulic retention time, An outflow (S15) for adjusting the residence time can be performed. The continuous batch reactor 100 may be operated in a batch mode with a floating ornamental reaction tank.

The samples were anaerobic digestion tank supernatant of Seoul A sewage treatment plant. The anaerobic digestion tank supernatant collected at the sewage treatment plant was refrigerated at 4 ℃ or less in the laboratory. The concentration range of the ammonia nitrogen of the influent water may be 220 mg / L to 300 mg / L, and may flow into the main body 101 at an average concentration of 260 mg / L during the operation period. It is possible to maintain the alkalinity / ammonia nitrogen ratio of 7.1 to 7.2 by supplementing the alkalinity required for nitrification before entering the main body 101. For the analysis, the ammonia nitrogen can be measured by Nessler's method based on a standard method, and the nitrite nitrogen and the nitrate nitrogen can be measured using IC (Ioc chromatography). The operation of the continuous batch reactor 100 can be stabilized quickly by using the microorganisms of the nitrification reactor in which the stable reaction has been induced.

11 shows the operation result of the continuous batch reactor 100 according to the embodiments of the present invention. Referring to FIG. 11, it can be seen that the nitrification rate according to the solids retention time and the hydraulic retention time. It is classified into O1 ~ O5 sections according to operating conditions and can be confirmed by Table 1. The solids retention time is denoted SRT and the hydraulic retention time is denoted HRT. The ammonia nitrogen concentration in the influent water was slightly different depending on the sampling period, but the average ammonia nitrogen concentration was 260 mg / L during the operation period. The results shown in FIG. 11 and Table 1 may vary depending on the characteristics of the influent water, such as the ammonia nitrogen concentration, and SRT and HRT may also be adjusted according to the characteristics of the influent water.

In the O1 section, the SRT was operated for 1 day. In the O1 section, the ammonia nitrogen removal efficiency was 90% and the nitrite removal rate was 76%. In the O2 section, the SRT was increased to set the SRT to 4 days. The O2 section was operated with the longest SRT during the entire operation period. The ammonia nitrogen removal efficiency was 90%, but the nitrification reaction was induced not by the nitrification reaction .

In the O3 interval, the HRT was kept constant and SRT was decreased to 2 days in order to stably induce the nitrification reaction. As a result of the operation of the O3 section, the ammonia nitrogen removal efficiency as high as the O2 section was shown, but the operation condition of the O2 section for the influent water was not preferable for the nitrification reaction.

It was confirmed that the nitrification reaction was stably induced by the operation condition of the O1 section under the same operating condition as the O1 section. The O5 section was operated with the same SRT as the O3 section in order to confirm whether complete nitrification was induced by the influence of the O2 operation condition in the O3 section. As a result of the operation of the O5 section, it was confirmed that the complete nitrification reaction was induced. This means that the O3 section is not affected by the O2 section, and the operating condition of the O3 section for the influent water is not preferable because the nitrification reaction is induced.

The O6 section was again operated under the same operating conditions as the O1 section, confirming that the nitrification reaction could be induced artificially. That is, in the continuous batch reactor 100 according to the embodiments of the present invention, SRT and HRT can be freely separated and regulated, and the nitrification reaction can be artificially induced through the regulation.

The O1, O4, O5, and O6 sections were adjusted to the same HRT, but the O5 section was adjusted to a longer SRT than the other sections. As a result, the sub-nitrification efficiency was superior to the nitrite sub-step in the remaining sections except the O5 section by as much as 75% or more. Thus, it can be confirmed that the nitrification reaction is closely related to SRT.

Operating condition HRT (days) SRT (Sun) Ammonia Nitrogen Removal Rate (%) Nitrification rate (%) O1 0.5 One 91 76 O2 One 4 90 20 O3 One 2 88 16 O4 0.5 One 92 80 O5 0.5 2 82 22 O6 0.5 One 91 85

Through the present example, it was confirmed that the nitrification reaction can be stably induced by controlling the operation conditions during the entire operation period. Under the SRT condition in which the nitrification reaction is induced, the treatment capacity of the influent water can be increased in the continuous batch reactor 100 of the same scale by adjusting the HRT.

In the present embodiment, as a result of operating the continuous batch reactor 100, the preferred SRT for inducing the nitrification reaction was 1 day, and SRT was found to be an important factor for the nitrification reaction. In addition, although stable nitrification reaction was not induced in the conventional continuous batch reactor, it was confirmed that stable nitrification reaction can be induced in the continuous batch reactor 100 according to the embodiments of the present invention. Therefore, when introducing the nitrification reaction into the wastewater treatment plant, the waste water treatment method or the continuous batch reactor 100 according to the embodiments of the present invention can be applied. Since the HRT and the SRT are separated and operated, The reaction efficiency is increased and the treating capacity of the influent water can be increased.

Hereinafter, specific embodiments of the present invention have been described. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

100: continuous batch reactor 101:
102: aeration unit 103: agitation unit
104: measuring unit 105:
106: inlet 107: pump
108: wastewater storage unit 110:
200: Anammox reaction device

Claims (1)

Introducing wastewater containing ammonia nitrogen;
Aeration step of supplying air to the wastewater;
Controlling the solid retention time (SRT) by discharging the wastewater;
A precipitation step of precipitating the wastewater; And
And adjusting the hydraulic retention time (HRT)
The nitrite nitrogen is formed through the nitrification reaction of the ammonia nitrogen,
Wherein the solids retention time is adjusted to 1 to 10 days (Day).

Images