KR20190072374A - Nitrogen Removal Methods of Sewage Using Autotrophic microorganism immobilized in Bead - Google Patents

Abstract

The present invention relates to a sewage treatment method using a carrier, on which aerobic ammonium oxidizing microorganisms and anaerobic ammonium oxidizing microorganisms are immobilized in order to efficiently remove nitrogen components contained in municipal wastewater or sewage. More specifically, the present invention includes: a coagulation sedimentation step of injecting a coagulant into sewage and then, separating the same into sludge and high quality water; a step of supplying the high quality water to a first aerobic reactor including the carrier where the ammonium oxidizing microorganisms are immobilized, and making the same react for a predetermined time; a step of supplying the effluent of the first aeration tank to an anoxic tank including a carrier, where ammonium oxidizing microorganisms are immobilized, and making the same react for a predetermined time; and a step of supplying the effluent of the anoxic tank to a second aeration tank including aerobic microorganisms, and making the same react for a predetermined time. In the sewage treatment method using a carrier on which ammonium oxidizing microorganisms are immobilized, the ammonium oxidizing microorganism of the carrier contained in the first aeration tank is an aerobic ammonium oxidizing microorganism, and the ammonium oxidizing microorganism of the carrier contained in the anoxic tank is an anaerobic ammonium oxidizing microorganism.

Description

Technical Field [0001] The present invention relates to a method for treating nitrogen in sewage using an autotrophic microorganism immobilized in a bead,

The present invention relates to a sewage treatment method using an aerobic ammonium oxidizing microorganism, an autotrophic microorganism, and a carrier on which an anaerobic ammonium oxidizing microorganism is immobilized, in order to efficiently remove nitrogen components contained in municipal sewage or sewage.

If a large amount of nitrogen is introduced into the water system, it may become toxic to aquatic environment, reduce residual DO in the water system, or cause eutrophication. In addition, it is necessary to maintain the concentration of nitrogen in the water system at a low level because it generates secondary disinfection byproducts when the chlorine is introduced during disinfection process during the physico-chemical method.

Biological processes using nitrification and denitrification are widely used as a method of removing such nitrogen. Nitrogen removal reactions in general biological processes are achieved by sequential progression of nitrification reactions in aerobic conditions (Equations 1 and 2) and denitrification under anaerobic conditions.

(1)

(One)

(2)

(2)

However, as can be seen from the above Equations 1 and 2, a large amount of oxygen is required to oxidize ammonia nitrogen, and the denitrification reaction in a biological process requires an organic carbon source as an electron donor of a microorganism for reduction of nitric acid or nitrite Therefore, the operation cost is increased accordingly.

In response to the problems of such biological processes, many studies have been made on a nitrogen removal method using anaerobic ammonium oxidizing microorganisms. An anaerobic ammonium oxidizing microorganism is an autotrophic microorganism that produces nitrogen (N ₂ ) by using ammonium (NH ₄ ⁺ ) and nitrite (NO ₂ ^- ) as a substrate under anaerobic conditions. The use of ammonium (NH ₄ ⁺ ) as an electron donor and nitrite (NO ₂ ^- ) as an electron acceptor do not require the addition of an organic carbon source unlike conventional biological processes, and the partial nitrification of ammonia nitrogen Is also reduced by about 60% in comparison with the conventional biological process, so that the aeration cost and the carbon source supply cost can be reduced.

In addition, the nitrogen removal process using the anaerobic ammonium oxidizing microorganism has a higher denitrification efficiency than the general biological process in which the maximum nitrogen removal efficiency does not exceed 0.3 kg-N / m ³ -day at 26 to 42 kg-N / m ³ -day great.

However, such anaerobic ammonium oxidizing microorganisms exist in the form of Candidatus Brocadia, Candidatus Kuenenia, Candidatus Scalindua, Candidatus Anammoxoglobus, and Candidatus Jettenia in the wastewater treatment process and natural nitrogen circulation system, and the growth rate is very slow to about 11 days , It is necessary to effectively control the microorganisms lost from the reaction tank in order for the nitrogen removal reaction by the anaerobic ammonium oxidizing microorganism to progress to a certain level.

In recent years, activated sludge containing anaerobic ammonium oxidizing microorganism is beaded by applying a comprehensive immobilization technique, and a technique of cultivating anaerobic ammonium oxidizing microorganism is developed, and it is possible to retain a high concentration of anaerobic ammonium oxidizing microorganism in the reactor for a long time .

However, in the anaerobic ammonium oxidizing bacteria incubation tank immobilized on polyvinyl alcohol (PVA), the nitrogen gas generated in the bead was not properly discharged to the outside of the bead during the long operation, resulting in expansion or destruction of the bead.

Partial nitrification, which is used as a pretreatment concept in the nitrogen removal process using anaerobic ammonium oxidizing bacteria, should effectively control the dissolved oxygen concentration (less than 0.5 mg / L) in the reaction tank. However, due to changes in microbial activity and influent water quality It is difficult to stably maintain a low oxygen concentration in the reaction tank.

Korean Patent No. 1040518

An object of the present invention is to provide a sewage treatment method using a carrier immobilizing an ammonium oxidizing microorganism capable of minimizing the supply of oxygen and an organic carbon source, thereby reducing the treatment cost.

It is another object of the present invention to provide a sewage treatment method to which a partial nitrification process is added in order to maximize the nitrogen removal effect by the anaerobic ammonium oxidizing microorganism.

In addition, it is an object of the present invention to provide a method for producing a carrier in which aerobic and anaerobic ammonium oxidizing microorganisms are immobilized.

According to another aspect of the present invention, there is provided a method of treating sewage using a carrier immobilized with ammonium oxidizing microorganisms, the method comprising the steps of: injecting a coagulant into sewage, separating the sludge into a supernatant, Supplying the first ox-acetic acid effluent to an anoxic tank containing a carrier immobilized with ammonium oxidizing microorganisms and reacting the same for a predetermined period of time; feeding the anoxic tank effluent to aerobic microorganisms Wherein the ammonium oxidizing microorganism of the carrier contained in the first aeration tank is an aerobic ammonium oxidizing microorganism and the ammonium oxidizing microorganism of the carrier contained in the anoxic tank is an anaerobic ammonium oxidizing microorganism .

Preferably, the flocculant to be injected into the flocculation and precipitation step is polyaluminum chloride (PAC) or aluminum polychlorosilicate (PACS).

It is preferable that the dissolved oxygen of the first aeration tank is maintained at 0.5 mg / L or more and 4 mg / L or less, and the partial nitrification reaction proceeds.

And precipitating the second aeration tank effluent to return a part of the precipitated sludge to the anoxic tank.

Further, in the present invention, the carrier immobilized with the ammonium oxidizing microorganism in the first aquarium may be prepared by preparing a mixed solution of PVA and alginate mixed with PVA and alginate, adding a solution containing aerobic ammonium oxidizing microorganism to the PVA- And a foaming agent to prepare a foamed-beaded solution, and titrating the foamed-beaded solution into a saturated boric acid solution containing calcium chloride to prepare a bead having sludge immobilized thereon.

Here, the foaming agent is sodium hydrogencarbonate (NaHCO ₃ ). In the foam-beaded solution, sodium bicarbonate (NaHCO ₃ ) is preferably mixed with 0.3 to 1.2 parts by weight with respect to 200 parts by weight of water.

Also, the carrier immobilized with the ammonium oxidizing microorganism in the anoxic tank may be prepared by preparing a mixed solution of PVA and alginate mixed with PVA and alginate, mixing the sludge containing the anaerobic ammonium oxidizing microorganism and the foaming agent into the PVA- - preparing a beaded solution, and titrating the foamed-beaded solution into a saturated boric acid solution containing calcium chloride to prepare beads having sludge immobilized thereon.

The foaming agent is sodium hydrogencarbonate (NaHCO ₃ ). In the foamed-beaded solution, sodium bicarbonate (NaHCO ₃ ) is preferably mixed with 0.6 to 2.4 parts by weight based on 200 parts by weight of water.

Further, the step of immersing the sludge-immobilized beads in the phosphoric acid solution may further include a step of increasing the mechanical strength of the beads, and the pH of the saturated boric acid solution containing calcium chloride is preferably 3 to 4.

The method may further include the step of immersing the beads having the sludge immobilized therein in distilled water to discharge sodium bicarbonate (NaHCO ₃ ) remaining in the beads and unreacted alginate to the outside of the beads.

In the sewage treatment method using the carrier immobilized with the ammonium oxidizing microorganism according to the present invention, since the organic substances and the suspended solids are removed in advance through the coagulation sedimentation process, partial nitrification and deammonification can be stably performed .

Further, according to the sewage treatment method of the present invention, since the deammonitization reaction is induced after the partial nitrification reaction, the supply of oxygen and the organic carbon source is not required and the operation cost can be reduced.

Furthermore, according to the sewage treatment method of the present invention, it is possible to induce immobilization of the ammonium oxidizing microorganism through controlling the content of the foaming agent of the carrier, and to secure stable water quality without loss of the carrier for a long period of time.

1 is a conceptual diagram of a sewage treatment method using the carrier immobilized with the ammonium oxidizing microorganism of the present invention.
FIG. 2 is a graph of the change of dissolved oxygen with the depth of the carrier.
FIG. 3 is a flow chart for explaining a method for producing a carrier to which the aerobic ammonium oxidizing microorganism of the present invention is immobilized.
4 is a flow chart for explaining a method for producing a carrier immobilized with the anaerobic ammonium oxidizing microorganism of the present invention.
5 is a SEM photograph of the beads produced.
Figure 6 shows the porosity results of the produced beads.
Fig. 7 shows partial nitrification results according to the amount of sodium hydrogencarbonate added.
8 is a result of loss of microorganisms in the carrier depending on the amount of sodium hydrogencarbonate added.
FIG. 9 shows the results of distribution of anaerobic ammonium oxidizing bacteria according to the amount of the blowing agent injected.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately The present invention should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention.

As shown in FIG. 1, the sewage treatment method using the carrier immobilized with the ammonium oxidizing microorganism of the present invention is characterized in that it comprises a flocculation step, a first unit reaction step, an oxygen-free reaction step, a second unit reaction step, .

In the flocculation and sedimentation step, the flocculant is injected into the flocculation and sedimentation tank, and the flotation material, the organic material and the phosphorus contained in the sewage are flashed through the rapid stirring and the slow stirring.

In the present invention, in order to minimize the supply of oxygen required for the growth of aerobic microorganisms and to minimize the inflow of organic matter that may inhibit the growth of the anaerobic ammonium oxidizing microorganism, the coagulation sedimentation step is preceded.

The coagulant may be any known coagulant such as iron salt or aluminum. However, polyaluminum chloride (PAC) or polyaluminum chloride silicate (PACS), which can minimize the consumption of alkalinity, desirable. These polychlorinated aluminum and poly (aluminum chloride) silicate are known coagulants, and their specific composition and production method are not described.

The supernatant obtained through the coagulation sedimentation step is supplied to the first aquarium containing the aerobic microorganisms (activated sludge) for oxidizing the organic matter and the carrier immobilized with the aerobic ammonium oxidizing microorganisms, and reacted for a predetermined time.

In the first aquarium, partial nitrite oxidation proceeds and organic matter contained in the supernatant is removed by an aerobic microorganism (activated sludge) that oxidizes organic matter. More specifically, the partial nitrification process is a step of oxidizing a part of the ammonia nitrogen contained in the supernatant to a nitrite nitrogen, and the reaction formula proceeds as shown in the following equation (3).

(3)

(3)

The partial nitrification step in the first aeration unit is preferably performed to oxidize the ammonia nitrogen of the supernatant by about 50% in consideration of the growth and oxidation reaction of the downstream anaerobic ammonium oxidizing microorganism.

 In the first aeration tank, the dissolved oxygen is preferably maintained in the range of 0.5 mg / L to 4 mg / L, more preferably 0.5 mg / L to 2 mg / L. If the dissolved oxygen is less than 0.5 mg / L, the oxygen required for the nitrification is insufficient. If the dissolved oxygen exceeds 4 mg / L, the oxygen is excessively accompanied by the nitrification reaction.

On the other hand, the aerobic ammonium oxidizing microorganisms of the first aquarium are preferably immobilized on a carrier. As shown in FIG. 2, since the dissolved oxygen is lowered as it enters the interior of the carrier, even if the bulk state of the first aquarium, that is, the dissolved oxygen concentration outside the carrier, deviates from the above range, the inside of the carrier immobilized with aerobic ammonium oxidizing bacteria, It is possible to maintain a low dissolved oxygen concentration required for the partial nitrification reaction, and thus it is possible to stably induce the partial nitrification reaction.

As shown in FIG. 3, the method of immobilizing the aerobic ammonium oxidizing microorganism on the carrier comprises the steps of preparing a mixed solution of PVA and alginate mixed with PVA and alginate, adding sludge containing aerobic ammonium oxidizing microorganism to the mixed solution of PVA and alginate, Preparing a foamed-beaded solution by mixing sodium hydrogencarbonate (NaHCO ₃ ), preparing a bead having a sludge immobilized by titrating the foamed-beaded solution into a saturated boric acid solution containing calcium chloride, Immersing the beads in a phosphoric acid solution to improve the mechanical strength of the beads, and immersing the beads in distilled water to induce swelling of the beads.

The above steps will be described in detail. First, PVA-alginate mixed solution and sludge are prepared. The PVA-alginate mixed solution is a solution in which polyvinyl alcohol (PVA) and alginate are mixed with distilled water. The solution is prepared by mixing 10 to 20 parts by weight of PVA and 1 to 5 parts by weight of sodium alginate per 100 parts by weight of water Can be used. For the uniform mixing of PVA and alginate, the PVA-alginate mixed solution may be further dissolved at a temperature of 100 ° C or higher for a certain period of time.

The sludge refers to sludge containing aerobic ammonium oxidizing microorganisms. It is preferable to use sludge of high concentration to improve the nitrification reaction, and sludge of high concentration can be prepared through gravity sedimentation and centrifugation. Further, the sludge may be sieved through a sieve having a size of 100 to 1,000 mu m to uniformize the sizes of the microorganisms.

Then, the PVA-alginate mixed solution and the sludge are mixed. The PVA-alginate mixed solution and the sludge may be mixed at a weight ratio of 1: 0.8 to 1: 1.

In the state that the PVA-alginate mixed solution and the sludge are mixed, sodium hydrogen carbonate (NaHCO ₃ ) is added more preferably than the foaming agent, and then mixed again. The sodium hydrogencarbonate (NaHCO ₃ ) is decomposed under an environment of pH 3 to 4 as inorganic foaming agent to produce carbon dioxide (CO ₂ ). Carbon dioxide (CO ₂ ) produced by decomposition of sodium hydrogencarbonate (NaHCO ₃ ) plays a role in forming pores in beads during bead formation. In the following description, a solution in which PVA-alginate mixed solution, sludge and sodium hydrogencarbonate (NaHCO ₃ ) are mixed is referred to as a " foaming-beaded solution ". On the other hand, for the purpose of controlling the specific gravity of the beads, zeolite may be further added to the foamed-beaded solution.

With the foamed-beaded solution ready, titrate the foamed-beaded solution in the mucilage state into a saturated boric acid (H ₃ BO ₃ ) solution containing calcium chloride (CaCl ₂ ). The calcium chloride (CaCl ₂ ) and the saturated boric acid (H ₃ BO ₃ ) are cross-linking agents for making a foam-beaded solution into a bead. The calcium chloride serves as a crosslinking agent for alginate and the saturated boric acid serves as a crosslinking agent for PVA. The saturated boric acid (H ₃ BO ₃ ) solution contains 0.5 to 1 part by weight of calcium chloride (CaCl ₂ ) per 100 parts by weight of water.

Expanded-bead screen as the titration solution is a saturated boric acid (H3BO ₃₎ a solution containing calcium chloride (CaCl _2), the PVA is cross-linked with the alginate and form the beads, the beads are immobilized is in the sludge is supported.

During the bead formation process, sodium bicarbonate (NaHCO ₃ ) contained in the foam-beaded solution is decomposed to generate carbon dioxide (CO ₂ ). Carbon dioxide (CO ₂ ) produced by the decomposition of sodium hydrogencarbonate (NaHCO ₃ ) is discharged outside the bead, and carbon dioxide (CO ₂ ) inside the bead is discharged to the outside of the bead, thereby forming pores inside the bead.

Since the pores of the carrier formed through the above process act as a passage through which the supernatant containing the bulk liquid, that is, ammonia nitrogen, moves, it is possible to keep the concentration of dissolved oxygen in the carrier low.

The content of sodium hydrogencarbonate (NaHCO ₃ ) in the foamed-beaded solution is preferably 0.15 to 0.6 parts by weight, more preferably 0.15 to 0.3 parts by weight based on 100 parts by weight of water. If the content of sodium hydrogencarbonate (NaHCO3) is less than 0.15 parts by weight, the diameter and the porosity of the pores are too low to allow the bulk liquid to migrate to the inside of the beads. Conversely, if the content exceeds 0.6 parts by weight, There may be a problem that it is leaked to the outside of the carrier. Particularly, when the concentration of dissolved oxygen in the bulk liquid is high, dissolved oxygen is kept high even in the interior of the carrier, and the nitrification reaction can proceed through the nitrification reaction.

On the other hand, as described above, since the optimum pH for decomposing sodium bicarbonate (NaHCO ₃ ) to carbon dioxide (CO ₂ ) is 3 to 4, the saturated boric acid (H ₃ BO ₃ ) solution containing calcium chloride (CaCl ₂ ) Should be adjusted to 3-4.

Although a method of forming pores in beads by using sodium hydrogen carbonate (NaHCO ₃ ) has been described above, pores may be formed using solid particles. That is, when the beads are completed with the solid particles contained in the foam-beaded solution, the solid particles do not chemically bond with the PVA or the alginate, so that the solid particles are desorbed from the beads And a pore that spatially connects the inside and the outside of the bead is formed at the site where the solid particles are desorbed. Here, the external physical impact of a certain strength means the contact between the beads by the operation of the stirrer, or may refer to an external physical impact to detach the solid particles from the bead.

The solid particles may be added to, mixed with, or premixed in the PVA-alginate mixed solution, and the solid particles are not particularly limited as long as they do not chemically react with PVA and alginate. However, Activated carbon having a size of 10 mu m to 1 mm or less can be used.

The beads formed through the above processes may be further immersed in 0.5 to 1 M phosphoric acid (KH ₂ PO ₄ ) solution to enhance the mechanical strength of the beads.

The prepared beads are washed with distilled water two to three times and then immersed in distilled water to induce a phenomenon of swelling, so that sodium bicarbonate (NaHCO ₃ ) remaining in the beads and unreacted alginate are discharged to the outside of the beads .

As described above, when the aerobic ammonium oxidizing microorganism is reacted for a predetermined time in the first aquarium containing a fixed carrier, a part of ammonia nitrogen is left as it is, but a part is oxidized to nitrite nitrogen. The first aeration tank reaction solution is supplied to an anoxic tank equipped with a carrier immobilizing anaerobic ammonium oxidizing microorganisms.

An anaerobic ammonium oxidizing microorganism immobilized on an anoxic tank does not require an organic carbon source and oxidizes ammonia nitrogen using NH ₄ ⁺ as an electron donor and NO ₂ ^- as an electron acceptor under anaerobic conditions, and inorganic carbon (HCO ₃ ^- ) is reduced to synthesize intracellular carbon (Equation 4).

(4)

(4)

As shown in FIG. 4, the method of immobilizing the anaerobic ammonium oxidizing microorganism on the carrier comprises the steps of preparing a mixed solution of PVA and alginate mixed with PVA and alginate, adding sludge containing anaerobic ammonium oxidizing microorganism to the mixed solution of PVA and alginate, Preparing a foamed-beaded solution by mixing sodium hydrogencarbonate (NaHCO ₃ ), preparing a bead having a sludge immobilized by titrating the foamed-beaded solution into a saturated boric acid solution containing calcium chloride, Immersing the beads in a phosphoric acid solution to improve the mechanical strength of the beads, and immersing the beads in distilled water to induce swelling of the beads.

The method of immobilizing the aerobic ammonium oxidizing microorganism on the carrier differs from the method of immobilizing the aerobic ammonium oxidizing microorganism on the carrier only in the content of the microorganisms fixed on the carrier and the foaming agent.

The sludge added to the PVA-alginate mixed solution is an anaerobic ammonium oxidizing microorganism. In the mixed state of the PVA-alginate mixed solution and the sludge, 0.1 to 1.2 parts by weight of sodium hydrogen carbonate (NaHCO ₃ ) , More preferably from 0.3 to 0.6 part by weight.

If the content of sodium hydrogencarbonate (NaHCO ₃ ) is less than 0.15 part by weight, the pore diameter or the porosity is too low, so that the bulk liquid is hardly moved to the inside of the bead, and the nitrogen gas generated in the oxidation process of ammonia nitrogen There is a fear that the beads are destroyed due to not being discharged. Anti-1.2 not only the diameter and the porosity of the pores is too large to immobilized microorganism can be discharged to the carrier outside exceeds parts by weight, as it may be easily broken beads due to external impact, the amount of sodium bicarbonate (NaHCO ₃₎ is the Lt; / RTI >

When the anaerobic ammonium oxidizing microorganisms are reacted in an anoxic tank containing a carrier immobilized thereon for a predetermined time, the remaining ammonia nitrogen is oxidized to nitrate, and some organic matter and phosphorus remain. The anoxic waste water having such characteristics is supplied to a second aquarium containing a aerobic microorganism inhabited on the lake. In the second aquarium, organic matter is removed by these aerobic microorganisms, and microorganisms are proliferated while consuming phosphorus and nitrogen.

Finally, after the reaction in the second aeration tank for a predetermined period of time, a sedimentation step for separating the microorganism (activated sludge) from the treated water is carried out in the sedimentation tank having a bottom-bottom sludge structure, and a part of the microorganisms (activated sludge) Is returned to the anoxic tank, and clean treated water on the upper settling tank is discharged to an advanced treatment or a river.

The carrier immobilized with the ammonium oxidizing microorganism according to an embodiment of the present invention and a method for producing the carrier have been described above. Hereinafter, the present invention will be described in more detail with reference to experimental examples.

<Production example of carrier>

15 g of PVA and 2 g of sodium alginate were mixed with 100 g of water to prepare a PVA-alginate mixed solution. Then, sludge containing 2.0 g (1.5 g to 2.5 g) of anaerobic ammonium oxidizing microorganism and 100 g of water was added to the PVA- . Then, 0 g, 0.3 g, 0.60 g, 1.2 g, and 2.4 g of sodium hydrogencarbonate (NaHCO ₃ ) were added to the mixed PVA-alginate solution, respectively, to prepare a foamed-beaded solution. Then, each foam-beaded solution was titrated into a saturated boric acid solution containing 0.5 to 1 g of calcium chloride on the basis of 100 g of distilled water to prepare beads, and the beads were reacted with 0.5 M phosphoric acid solution.

Figure 5 is a SEM photo of the prepared beads, the pores compared to injected in the case of non-added a sodium (NaHCO ₃₎ carbonate beads (0g), sodium bicarbonate (NaHCO ₃₎ beads as shown in Figure 5 It can be confirmed that it is hardly formed. Also, as the amount of sodium hydrogencarbonate (NaHCO ₃ ) is increased, the pore size becomes larger. This result is consistent with the porosity measurement result shown in FIG. Referring to FIG. 6, it can be seen that the porosity increases as the amount of sodium hydrogencarbonate (NaHCO ₃ ) is increased.

FIG. 7 is a graph showing the relationship between the amount of sodium bicarbonate (NaHCO ₃ ) added and the amount of beads (0 g) to which no sodium hydrogencarbonate (NaHCO ₃ ) , 1.2 g) were prepared and put into the first aeration tank.

3.5 mg/L, BOD 120.2

23.8 mg/L, COD 105.2

10.2 mg/L 및 SS 147.1

52.9 mg/L 였다.At this time, representative pollutants of raw water include ammonia nitrogen concentration 26.4

3.5 mg / L, BOD 120.2

23.8 mg / L, COD 105.2

10.2 mg / L and SS 147.1

52.9 mg / L.

As can be seen from the results of FIG. 7, in the case of using beads not charged with sodium hydrogencarbonate (NaHCO ₃ ), it is necessary to maintain the dissolved oxygen concentration at about 6.0 mg / L in order to achieve a nitrification rate of about 50%. On the other hand, the beads injected with sodium bicarbonate (NaHCO ₃₎ 0.3g as about 4.5 mg / L, from about 4.0 mg / L and about 2.0 mg / L In the 1.2g 0.6g, sodium hydrogen carbonate (NaHCO ₃₎ It can be seen that even if the concentration of dissolved oxygen is kept low, it is possible to achieve the same nitrification rate.

8 is a result of loss of microorganisms in the carrier depending on the amount of sodium hydrogencarbonate (NaHCO3) added.

The contents of water, PVA, alginate and microorganisms were 200g, 15g, 2g and 2g, respectively. The amounts of added foaming agent (NaHCO ₃ ) were changed to 0.6g, 1.2g and 2.4g, respectively.

The carrier prepared at the above mixing ratio was filled in distilled water, and the beads were sampled at intervals of time with stirring to measure the microorganisms discharged to the outside of the carrier.

As can be seen from the results of FIG. 8, when 0.6 g of sodium hydrogencarbonate (NaHCO ₃ ) was injected, about 1.1% of the lost microorganisms and 5.4% of the 1.2 g of injected microbes showed that the microorganisms were stably fixed in the carrier Can be confirmed. On the other hand, when 2.4 g of sodium hydrogencarbonate (NaHCO ₃ ) was injected, it was confirmed that microorganisms were lost up to 16%.

FIG. 9 shows a synthetic wastewater which is similar to the partial nitrification reaction effluent in order to investigate the suitability of the carrier to which the anaerobic ammonium oxidizing microorganism is impregnated. The NH ₄ ⁺ -N and NO ₂ ^- N concentrations of the used wastewater were 20 mg / L and 20 mg / L, respectively. The contents of water, PVA, alginate and microorganisms were 200g, 15g, 2g and 2g, respectively, and the contents of foaming agent were adjusted to 0g, 0.6g, 1.2g and 2.4g, respectively. The time and reaction temperature were maintained at 30 ° C for 3 hours, respectively.

As can be seen from FIG. 9, when sodium hydrogencarbonate (NaHCO ₃ ) is not included, diffusion of the substrate into the carrier is not performed smoothly, so that the anaerobic ammonium microbes are concentrated on the outside of the carrier, while sodium hydrogen carbonate (NaHCO 3) The anaerobic ammonium microorganisms are distributed not only on the outside but also on the inside of the carrier, especially when 1.2 g of sodium hydrogencarbonate (NaHCO ₃ ) is injected.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It is to be understood that various changes and modifications may be made without departing from the scope of the appended claims.

Claims (11)

A coagulation sedimentation step of injecting coagulant into the sewage and then separating it into sludge and supernatant;
Supplying the supernatant to a first aquarium containing a carrier immobilized with an ammonium oxidizing microorganism and reacting the same for a predetermined time;
Supplying the first aeration tank effluent to an anoxic tank containing a carrier immobilized with an ammonium oxidizing microorganism and reacting for a predetermined time;
Supplying the anoxic tank effluent to a second aquarium containing aerobic microorganisms and allowing the anaoxic tank effluent to react for a predetermined time,
Wherein the ammonium oxidizing microorganism of the carrier contained in the first aeration tank is aerobic ammonium oxidizing microorganism,
Wherein the ammonium oxidizing microorganism of the carrier contained in the anoxic tank is an anaerobic ammonium oxidizing microorganism.
The method according to claim 1,
Wherein the coagulant injected into the flocculation and sedimentation step is polyaluminumchloride (PAC) or aluminum polychloroaluminate (PACS).
3. The method of claim 2,
Wherein the dissolved oxygen in the first aeration tank is maintained at 0.5 mg / L or more and 4 mg / L or less, thereby progressing the partial nitrification reaction.
The method according to claim 1,
Further comprising the step of precipitating the second aquarium effluent to return a part of the precipitated sludge to the anoxic tank.
The method according to claim 1,
The carrier to which the ammonium oxidizing microorganism of the first aquarium has been immobilized,
Preparing a PVA-alginate mixed solution in which PVA and alginate are mixed;
Preparing a foamed-beaded solution by mixing the PVA-alginate mixed solution with sludge containing an aerobic ammonium oxidizing microorganism and a foaming agent; And
And a step of titrating the foamed-beaded solution into a saturated boric acid solution containing calcium chloride to prepare a bead having sludge immobilized thereon, wherein the ammonium-oxidized microorganism is immobilized on the support.
6. The method of claim 5,
Wherein the foaming agent is sodium hydrogencarbonate (NaHCO ₃ ), and 0.3-2.2 parts by weight of sodium hydrogencarbonate (NaHCO ₃ ) is mixed with 200 parts by weight of water in the foam-beaded solution. Sewage treatment method using carrier.
The method according to claim 1,
The carrier to which the ammonium oxidizing microorganism of the anoxic tank is immobilized,
Preparing a PVA-alginate mixed solution in which PVA and alginate are mixed;
Preparing a foamed-beaded solution by mixing the PVA-alginate mixed solution with a sludge containing an anaerobic ammonium oxidizing microorganism and a foaming agent; And
And a step of titrating the foamed-beaded solution into a saturated boric acid solution containing calcium chloride to prepare a bead having sludge immobilized thereon, wherein the ammonium-oxidized microorganism is immobilized on the support.
8. The method of claim 7,
Wherein the foaming agent is sodium hydrogencarbonate (NaHCO ₃ ), and sodium hydrogencarbonate (NaHCO ₃ ) is mixed in 0.6 to 2.4 parts by weight with respect to 200 parts by weight of water in the foam-beaded solution. Sewage treatment method using carrier.
9. The method according to any one of claims 5 to 8,
Further comprising the step of immersing the beads in which the sludge is immobilized in the phosphoric acid solution to enhance the mechanical strength of the beads.
10. The method of claim 9,
Wherein the pH of the saturated boric acid solution containing calcium chloride is from 3 to 4.
9. The method according to any one of claims 5 to 8,
Further comprising the step of immersing the beads in which the sludge is immobilized in distilled water to discharge sodium bicarbonate (NaHCO ₃ ) and unreacted alginate remaining in the beads to the outside of the beads. Processing method.

Images