KR20140142991A - Artificial light installed biological wastewater treatment process - Google Patents

Abstract

The present invention relates to an advanced wastewater treatment system using an artificial light source, and, more specifically, to an advanced wastewater treatment system, which includes a phosphorus elution process, a denitrification process, a nitrification process, a precipitation process and a discharge process. The advanced wastewater treatment system using artificial light induces partial nitrification, which suppresses conversion of ammonia into nitrogen nitrate (NO3-N) due to the nitrification reaction by irradiating artificial light during the nitrification process so as to improve the removal rate of nitrogen, and reduces the blow costs, carbon sources necessary for the denitrification, and the consumption of alkaline.

Description

{Artificial light installed biological wastewater treatment process}

[0001] The present invention relates to a wastewater treatment system using an artificial light source, and more particularly, to a wastewater treatment system including a phosphorus leaching process, a denitrification process, a nitrification process, a precipitation process, And a partial nitrification inhibiting ammonia from being converted into nitric oxide (NO3-N) by a nitrification reaction.

Various researches on wastewater treatment methods have been suggested due to river pollution due to the development of industrialization in the world. The treatment method of wastewater can be divided into physical, chemical and biological treatment methods. Generally, the wastewater treatment method includes a first treatment step of physically removing suspended particles of a predetermined size included in the wastewater, and a second treatment step of removing organic matter of the wastewater Lt; / RTI >

In general, the secondary treatment stage using biologically activated sludge method is an anthropogenic formation of anaerobic condition, anoxic condition and aerobic condition to remove nitrogen and phosphorus, so that the mechanism of phosphorus removal proceeds in anaerobic condition, and nitrogen in anaerobic condition Removal mechanism and nitrification reaction occur under aerobic conditions. Especially, to maintain the aerobic condition, it is necessary to inject air artificially and it is the largest part of operation cost of sewage treatment plant. The wastewater from which nitrogen and phosphorus are removed is separated from microorganisms and water by gravity precipitation, pressurization, or separation membrane, and after disinfection process with UV, chlorine, ozone, etc., water is discharged out of the system and part of the sludge is returned And the other is returned to the anaerobic tank or the anoxic tank through the line, and the remainder is discarded or recycled through processes such as concentration and dehydration. In aerobic conditions, organic nitrogen and ammonia nitrogen in wastewater are oxidized by nitrifying microorganisms and converted into nitrite nitrogen or nitrate nitrogen. The nitrified wastewater is then returned to anoxic conditions, which are subjected to anoxic conditions, and is then reduced to nitrogen gas by the denitrifying microorganisms and discharged into the atmosphere to be removed from the wastewater. In anaerobic conditions, bio-P (Biological Phosphorus Removing bacteria) microorganisms synthesize organic matter in wastewater into high molecular substances such as PHA and PHB in bacteria and decompose Poly-P present in bacteria. When these bacteria enter into anaerobic conditions under anaerobic conditions, phosphorus is taken into the body of microorganisms in the wastewater by ingesting an excessive amount of phosphorus than necessary in the body, and the phosphorus is removed from the wastewater by disposing the microorganisms. This biological nitrogen and phosphorus treatment method requires a large amount of energy for air injection and has a problem that nitrogen and phosphorus removal efficiency are drastically lowered when C / N (COD / Nitrogen) ratio and C / P (COD / Has occurred. In addition, there is a problem in that a large amount of excess sludge is generated and a separate facility and cost for additional sludge treatment are added.

In general, nitrification is performed by AOB (Ammonia Oxidizing Bacteria) in one step nitrification (oxidation of ammonia (NH ₄ -N) to nitrite (NO ₂ -N)) and NO ₂ (nitrite oxidizing bacteria) ₂ -N is oxidized to NO ₃ -N). In addition, oxygen is needed to promote aerobic microbial activity and is most needed in the nitrification process. Wastewater treatment consumes a great deal of energy in mechanical operations such as blowers, pumps, and agitators, and consumes 30-50% of the total energy costs, especially in the blowing process.

Korean Patent No. 100460214 discloses that micro-algae (photosynthetic microorganisms) are used instead of bacterial-based microorganisms for nitrogen removal, but micro-algae alone releases nitrogen into the air to remove nitrogen. It can not be expected that a high efficiency nitrogen removal rate can not be expected and a high efficiency removal rate can not be expected due to the inability to utilize the characteristics of phosphorus removal bacteria known as Luxury Uptake.

Japanese Unexamined Patent Application Publication No. 2000-093951 discloses an artificial light irradiating unit having an artificial light source for irradiating artificial light to a photocatalyst of a sewage treatment unit and a light intensity detecting unit for detecting the intensity of natural light detected by the light intensity detecting unit and / The artificial light control unit for controlling the intensity of the artificial light based on the concentration of the organic substance in the wastewater is described. However, since the artificial light controls the activity of the photocatalyst by the artificial light, it does not affect the nitrification of the aeration tank, No. 10945458 automatically adjusts the process according to the total nitrogen concentration difference, the ammonia nitrogen concentration value, the nitrate nitrogen concentration value, the redox potential difference value and the phosphorus concentration, thereby removing nitrogen and phosphorus in the sewage water with high efficiency However, not only a large number of variables to be controlled exist, but also all variables Since it is required to measure and control the device, there is a difficulty of the complex and maintenance.

In addition, many studies on partial nitrification have been conducted recently. However, when partial nitrification is possible, high pH, low DO, and high concentration NH3 are stably maintained in the case of high concentration ammonia such as livestock wastewater, industrial wastewater, And the partial nitrification has not been successful in a real scale sewage treatment up to now.

As a result, the present inventors have made intensive efforts to solve the above problems, and as a result, they have found that when the artificial light is irradiated to the sewage treatment process to control the reaction mechanism of the nitrification process and the nitrification cost reduction and the C / N (carbon / nitrogen) It was confirmed that partial nitrification could be induced so as to reduce the external carbon source to be injected, and the present invention was completed.

It is an object of the present invention to provide a wastewater treatment system using artificial light, which is capable of inducing partial nitrification of ammonia in a nitrification process of a wastewater treatment system, thereby reducing shipping cost and carbon source necessary for denitrification.

In order to achieve the above object, the present invention provides a wastewater treatment system comprising an anaerobic tank, an anoxic tank, an aeration tank, and a settling tank sequentially including an agitator, wherein the anaerobic tank includes a first pipe through which wastewater flows, And the second pipeline is connected to the first pipeline, and the first pipeline is connected to an external transfer pipe connected to the settling tank, and the anoxic tank is connected to the second pipeline through which the anaerobic tank treated in the anaerobic tank flows, A third pipe connected to the aeration tank and connected to the aeration tank for partially conveying aeration tank treated water, and the aeration tank is connected to a third pipe through which the anoxic tank treated water treated in the anoxic tank flows, a fourth pipe through which aeration tank treated water is discharged, A first internal return pipe for returning a part of the aeration tank treated water is connected to the anoxic tank And an artificial light source part is disposed inside or above the aeration tank to induce partial nitrification of the treated anoxic tank treated water, and the settling tank is provided with a fifth pipe through which the aeration tank treated in the aeration tank flows, And an external transfer pipe for transferring the sludge of the settling tank to the anaerobic tank are connected to the sixth piping.

Further, the re-aeration tank may further include a re-aeration tank between the aeration tank and the settling tank. The re-aeration tank may further include a fourth pipe through which the aeration tank effluent discharged from the aeration tank flows, a fifth pipe through which the re- And a second internal return pipe for returning a part of the water is connected.

Another example of the present invention relates to a wastewater treatment system in which a denitrification process, a nitrification process, a precipitation process, and a discharge process are continuously performed in an anaerobic tank including a stirrer and a reaction tank sequentially in series, The anaerobic tank is connected to a first pipe through which wastewater flows, a second pipe through which the anaerobic tank-treated water is discharged, an inner transfer pipe connected to the reaction tank and to which a mixed water of sewage and sludge is partially conveyed, and the anaerobic tank A third pipe through which the treated water is discharged, an inner conveying pipe connected to the anaerobic tank and partially conveying the mixed water of sewage and sludge to the anaerobic tank is connected, and the artificial light source unit is connected to the inside , Wherein the artificial light source part The irradiated, there is provided a wastewater treatment step height system for deriving a portion of the nitrification treated water.

In addition, the wastewater treatment system includes a control unit for automatically adjusting the light irradiation time of the artificial light source unit according to the NO2-N concentration in the aeration tank. The operation of the control unit is to stop the irradiation of light according to the previously set NO2-N concentration. The concentration of NO2-N can be determined by analyzing the number of NO2-N automatic analyzers and experimental personnel installed in the aeration tank. The desirable NO2-N concentration should be kept below 5 mg / Liter.

In the present invention, the artificial light source unit may include at least one artificial light source installed at regular intervals in the reactor; An artificial light source casing provided outside the artificial light source and having water tightness; The light source of the artificial light source unit may include a light source such as an incandescent lamp, a fluorescent lamp, a mercury lamp, a sodium lamp, a halogen lamp, etc., a light emitting diode ), An organic light emitting diode (OLED), and an active organic light emitting diode (AMOLED).

The wastewater treatment system according to the present invention induces partial nitrification by irradiating the artificial light to the sewage treatment process, thereby reducing the oxygen supply energy cost necessary for nitrification and improving the nitrogen removal rate by the denitrification reaction , The necessity of injecting an external carbon source to a wastewater having a low C / N ratio is alleviated, and an alkali is produced by denitrification even under a low C / N ratio.

1 is a basic conceptual drawing of the present invention.
2 is a flowchart of a wastewater treatment process system including an artificial light irradiation apparatus installed in a first aeration tank according to the present invention.
3 is a view of an artificial light irradiation apparatus installed in an SBR reaction tank according to the present invention.
Figure 4 is an embodiment according to the present invention
5 is a graph of results of an embodiment according to the present invention.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

The term " piping " in the present invention means not only a pipe-type piping as a means for connecting a reaction tank or a settling tank in which each operation is performed, but also various types of pipes It may be of any form as long as it is connected to be transferred to the reaction tank or the settling tank.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, configurations and effects according to preferred embodiments of the present invention will be described in detail with reference to the drawings.

The present invention relates to a wastewater treatment system including aeration tank in which an artificial light irradiation apparatus is installed in a wastewater treatment system.

Fig. 1 is a conceptual diagram of the present invention, showing an example of a bioreactor in which a nitrification reaction takes place. Here, the artificial light source may be installed in the water inside the bioreactor or directly above the bioreactor.

The nitrification reaction of ammonia is a first-stage nitrification reaction which produces nitrite (NO2-N) by AOB (Ammonia Oxidizing Bacteria) in a wastewater treatment system as shown in Formula 1, nitrite oxidation by a nitrite oxidizing bacteria And a second-stage nitrification reaction to produce acidic nitrogen (NO3-N).

(Formula 1)

Also, in the wastewater treatment system, the denitrification reaction takes place in the anoxic condition as in the formula (2). As shown in the formula (2), carbonization is accompanied by the consumption of carbon in order to be denitrified, and carbon required to produce nitrogen from nitrate nitrogen requires about 40% more carbon than nitrogen from nitrite.

(2)

In addition, since NOB bacteria are reported to be less adaptive to AOB in abrupt changes in habitat conditions, it can inhibit the NOB activity by inducing light to nitrate bacteria and induce partial nitrification.

Accordingly, as shown in FIG. 1, the artificial light is irradiated inside or above the bioreactor to inhibit the activity of the NOB, thereby inducing the two-step nitrification process of the chemical formula 1 to proceed or partially proceed, As well as reducing the amount of oxygen needed for nitrification and improving the rate of nitrogen removal.

Fig. 2 shows a wastewater treatment system using an A2O process in which an artificial light source is installed in aeration tank. This is a wastewater treatment process system in which an anaerobic tank, an anoxic tank, aeration tank, and a settling tank are sequentially included in an agitator, and the first pipe through which the wastewater flows into the anaerobic tank and the second pipe through which the anaerobic tank treated water is discharged, Wherein the anoxic tank is connected to the first pipe through a second pipe connected to the settling tank, the anoxic tank includes a second pipe through which the anaerobic tank treated in the anaerobic tank flows, a third pipe through which the anoxic tank treated water is discharged, Wherein the aeration tank is connected to a third pipe through which the anoxic tank treated water treated by the anoxobic tank flows, a fourth pipe through which the aeration tank treated water is discharged, and a fourth pipe which discharges the aeration tank treated water by the anoxic tank The first internal return pipe is connected, and the artificial light source unit is connected to the aeration tank It induces partial nitrification to the number of inlet anoxic treatment, including inside or immediately above.

As described above in the aeration tank, the first stage reaction proceeds with nitrous acid (NO2-N) by ammonia and AOB, and the second stage reaction proceeds with nitrate nitrogen (NO3-N) by the action of NOB. Here, because the rate of the second-step reaction is faster than the reaction rate of the first-step reaction, partial nitrification in which nitrite is accumulated is not easy to be performed. Accordingly, in the present invention, by suppressing the activity of NOB by irradiating light using an artificial light source, nitrite is prevented from being converted into nitrate by the second-step reaction, thereby inducing partial nitrification, which causes accumulation of nitrite in the aeration tank Respectively.

Partial nitrification is carried out and a part of aeration tank treated with relatively high concentration of nitrite is returned to an anoxic tank for denitrification. Since the concentration of nitrite is relatively high, the amount of carbon required for denitrification is higher Very low. In addition, a part of the aeration tank treated water is discharged to the settling tank by the fifth pipe.

The sedimentation tank is connected to a fifth pipe through which aeration treatment water treated in the aeration tank is introduced, a sixth pipe discharging the sedimentation treatment water, and an external conveyance pipe for conveying the sludge of the sedimentation tank to the anaerobic tank. The sludge and water are separated and the water is discharged to the outside through the sixth pipe. A part of the sludge containing the microorganism is transferred to the first pipe by the external return pipe and introduced into the anaerobic tank together with the incoming wastewater. Separation of sludge and water in the settling tank is carried out by gravity precipitation, pressurization, or separation membrane. Water is discharged out of the system after UV, chlorine, and ozone are sterilized.

In the meantime, the present invention may further comprise a re-aeration tank between the aeration tank and the settling tank, wherein the re-aeration tank includes a fourth pipe through which the aeration tank treated water discharged from the aeration tank, a fifth pipe through which the re- And a second internal return pipe for conveying a part of the rebarification treatment water.

The re-aeration tank causes a second-stage reaction to occur in the aeration tank with a high concentration of nitrite by partial nitrification. If the concentration of nitrite is excessively high, it inhibits the phosphorus leaching of the phosphorus removal microorganism and the phosphorus uptake in the aeration tank in the anaerobic tank. Therefore, the second stage reaction is carried out from the reboiler to nitrogen dioxide. Preferably, the concentration of NO2-N should be kept below 5 mg / liter. In the reboiler, NO2-N is oxidized to NO3-N in order to prevent the inhibition of HNO2 gas generated by NO2-N and NO2-N.

In addition to the re-aeration tank, a second anoxic tank may be further included between the anoxic tank and the aeration tank. In this case, a part of the aeration tank-treated water is returned to the second anoxic tank in the aeration tank, and the reboiler treated water in the rebarification tank is returned to the anoxic tank, and the partially treated water in the anoxic tank is returned to the anaerobic tank. This reactor configuration is intended to maximize the nitrogen and phosphorus removal rate, and the complete nitrification reaction of NO ₂ -N in the reboiler and the denitrification reaction in the second anoxic tank proceed to improve the nitrogen and phosphorus removal rates of the sewage having a low C / N ratio .

The present invention includes a control unit for controlling the light irradiation time of the artificial light source unit according to the concentration of NO ₂ -N in the aeration tank in the activated sludge process. The control unit includes a device for reducing the amount of light and the irradiation time when the concentration of NO ₂ -N in the re-aeration tank exceeds 5 mg / liter. It also includes a control function to irradiate / non-irradiate the light irradiation time in a short period of 10 minutes or less.

The artificial light source unit includes at least one artificial light source installed at a predetermined interval in the reactor, an artificial light source casing provided outside the artificial light source and having water tightness, a foreign matter attached to the surface of the artificial light source casing, Includes casing cleaning wiper to clean. At this time, the outer wall coating of the artificial light source casing is selected from the group consisting of super water repellent coating, ceramic coating and silicone coating, and preferably a ceramic coating can be used.

In the present invention, the artificial light source is selected from the group consisting of an incandescent lamp, a fluorescent lamp, a mercury lamp, a sodium lamp, a halogen lamp, an organic light emitting diode (OLED), and an active organic light emitting diode (AMOLED) A diode (LED) can be used. Preferably, LEDs that are easy to produce a single wavelength are optimal. As the wavelength of the light source, it is possible to mix red light, green light, and yellow light based on the blue light at an appropriate ratio, or to install the blue light alone.

Another example of the present invention relates to an SBR wastewater treatment process system in which a denitrification process, a nitrification process, a precipitation process, and a discharge process are continuously performed in an anaerobic tank including an agitator and a reaction tank serially serially In general, the SBR wastewater treatment process is a process in which wastewater inflow and wastewater outflow occurs in a single reaction tank, and each unit process is continuously performed according to the arrangement of the time set. That is, as the inflow process, the reaction process, the precipitation process, and the discharge process proceed according to the predetermined time sequence, the reaction conditions are controlled to remove nitrogen and phosphorus.

In the present invention, an anaerobic tank in which phosphorus leaching of a microorganism occurs together with a reaction tank is additionally provided so that volatile fatty acids (VFAs) contained in influent water are selectively used by Bio-P (phosphorus accumulating microorganism) Thereby enabling high-efficiency removal of phosphorus by excessive consumption. In the reaction tank, a nitrification reaction, a nitrogen removal, a precipitation process, and a discharge process are performed.

In the SBR wastewater treatment system of the present invention, the anaerobic tank is connected to a first pipe through which wastewater flows, a second pipe through which the anaerobic tank-treated water is discharged, an inner transfer pipe connected to the reaction tank and partially conveying the sewage and sludge mixture, A third pipe through which the treated water is discharged; an inner conveying pipe connected to the anaerobic tank for conveying the sewage and sludge mixture in the anaerobic tank partially to the anaerobic tank; And an artificial light source part is installed inside or above the reaction vessel.

The artificial light source unit irradiates light during the nitrification process of the reaction tank to induce partial nitrification of the treated water as described above. In this case, the light irradiation time of the artificial light source unit is changed from NO ₂ -N And a control unit for controlling the concentration of the liquid.

When the concentration of nitrite in the reaction tank is excessively high due to partial nitrification, the phosphorus leaching of the phosphorus-removing microorganism in the anaerobic tank and the phosphorus uptake action in the reaction tank are inhibited. Therefore, the concentration of NO ₂ -N is preferably 5 mg / liter or less .

In addition, the artificial light source and artificial light source are also applied to the SBR wastewater treatment process system as described above.

Example :

From November 7, 2012 to December 12, 2012, the 2L capacity bioreactor was operated using the actual sewage treatment plant influent for 36 days, and the experimental conditions are shown in Table 1.

Table 1 Bioreactor experimental conditions

FIG. 5 shows the results of this experiment. In the experiment, the total nitrogen (TN) removal rate and the concentration of nitrite (NO2-N) were measured in the control reactor without the light irradiation, the cool white light, and the red & Respectively.

Table 2 summarizes the results shown in FIG. 5, where the average TN sludge removal rate for normal activated sludge without artificial light was 63.8%, while that for Cool White and Red & Blue light was 70.8% and 69.2%, respectively Control Reactor, respectively, by 7% and 5.4%, respectively.

The concentration of NO ₂ -N in the effluent was 1.089 mg / L in the control reactor and 7.093 mg / L and 7.806 mg / L in Cool White and Red & Blue, respectively, indicating that partial nitrification proceeded under artificial light irradiation conditions have.

Table 2 Experimental results

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments, It will be apparent that the scope is not limited. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (8)

1. A wastewater treatment system in which an anaerobic tank, an anoxic tank, aeration tank, and a settling tank are sequentially connected in series including an agitator,
Wherein the anaerobic tank is connected to a first pipe through which wastewater flows and a second pipe through which the anaerobic tank-treated water is discharged,
Wherein the first pipe is connected to an external transfer pipe connected to the settling tank,
The anoxic tank is connected to a second pipe through which the anaerobic tank treated in the anaerobic tank flows, a third pipe through which the treated water from the anaerobic tank is discharged, and a first internal return pipe connected to the aeration tank for partially transporting the aeration tank treated water.
Wherein the aeration tank is connected to a third pipe through which the anoxic tank treated water treated in the anoxic tank flows, a fourth pipe through which aeration tank treated water is discharged, and a first internal return pipe that carries a part of the aeration tank treated water by the anoxic tank, In the anoxic tank treated water including the inside or the upper part of the aeration tank, partial nitrification is induced,
Wherein the settling tank is connected to a fifth pipe through which the aeration tank treated water is treated in the aeration tank, a sixth pipe discharging the settling tank treated water, and an external return pipe for conveying sludge by the anaerobic tank. The apparatus according to claim 1, further comprising a re-aeration tank between the aeration tank and the settling tank, wherein the re-aeration tank is provided with a fourth pipe through which the aeration tank treated water discharged from the aeration tank, a fifth pipe through which the re- And a second internal return pipe for conveying a part of the aeration tank treated water is connected to the wastewater treatment facility. The wastewater treatment system according to claim 1, further comprising a control unit for adjusting the light irradiation time of the artificial light source unit according to NO2-N concentration in the aeration tank. And a nitrification process, a precipitation process, and an evacuation process are successively performed in a reaction tank, wherein the anaerobic tank includes an agitator and a reaction tank in series,
The anaerobic tank is connected to a first pipe through which the wastewater flows, a second pipe through which the anaerobic tank-treated water is discharged, an inner transfer pipe connected to the reaction tank and to which the sewage and sludge mixed liquor is partially transferred,
A second pipeline through which the anaerobic tank treated in the anaerobic tank flows into the reaction tank, a third pipeline through which the treated tank effluent is discharged, and an inner transfer pipe connected to the anaerobic tank and partially conveying the mixed solution of sewage and sludge with the anaerobic tank, The artificial light source part is contained in the interior of the reaction vessel or directly above it
Wherein the artificial light source unit irradiates light during the nitrification process of the reaction tank to induce partial nitrification of the treated water. 5. The wastewater treatment system according to claim 4, further comprising a control unit for controlling the light irradiation time of the artificial light source unit according to the concentration of NO ₂ -N in the aeration tank. 6. The light source unit according to any one of claims 1 to 5,
At least one artificial light source arranged at regular intervals in the reactor;
An artificial light source casing provided outside the artificial light source and having water tightness;
And a casing cleaning wiper installed on the outside of the artificial light source casing to clean foreign matter attached to the surface of the artificial light source casing. 7. The wastewater treatment process system of claim 6, wherein the surface of the artificial light source casing is coated with a coating selected from the group consisting of super water repellent coating, silicone coating and ceramic coating. The organic light emitting diode according to any one of claims 1 to 5, wherein the light source of the artificial light source unit is a light emitting diode (LED), an organic light emitting diode (OLED), and an active type organic light emitting diode AMOLED) for the wastewater treatment system.

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