KR100419429B1 - Apparatus for treating highly concentrated nitrogenous waste water and method for treating highly concentrated nitrogenous waste water using the same - Google Patents

Abstract

The present invention provides a wastewater treatment apparatus for treating wastewater containing high concentrations of organic nitrogen and ammonia nitrogen and a wastewater treatment method using the same. The wastewater treatment apparatus of the present invention includes an oxygen-free tank in which a reaction of denitrifying by denitrifying bacteria and reducing nitrite nitrogen and nitrate nitrogen to a nitrogen gas is carried out by introducing wastewater into the denitrifying bacteria and the organic matter in the wastewater; The first process in which the treated water passed through the oxygen-free tank is introduced, and the reaction of lowering the carbon / nitrogen ratio in the treated water is performed to oxidatively decompose the organic matter contained in the treated water using an aerobic microorganism to be suitable for subsequent partial nitrification reaction. Aeration tank; The treatment water flowing through the first aeration tank is introduced, and the reaction of partially nitrifying the ammonia nitrogen in the treated water having passed through the first aeration tank into nitrate nitrogen and nitrite nitrogen using ammonia oxidizing bacteria and nitrite oxidizing bacteria. 2 aeration tanks; An internal conveying line for conveying a portion of the treated water that has passed through the second aeration tank to the anoxic tank; The treated water that has passed through the second aeration tank flows in, and the step of immersing the sludge in the treated water and discharging the supernatant as the final treated water includes a settling tank; And a sludge conveying line for conveying a part of the sludge in the settling tank to the anoxic tank. According to the wastewater treatment apparatus of the present invention, wastewater containing a high concentration of organic nitrogen and ammonia nitrogen, but containing a relatively low concentration of organic matter, and having a low carbon / nitrogen ratio can be treated stably, economically and efficiently.

Description

Apparatus for treating highly concentrated nitrogenous waste water and method for treating highly concentrated nitrogenous waste water using the same}

The present invention relates to a wastewater treatment apparatus for treating wastewater containing high concentrations of organic nitrogen and ammonia nitrogen, and to a wastewater treatment method using the same, and more particularly to a high concentration of organic nitrogen and ammonia nitrogen. The present invention relates to a wastewater treatment apparatus suitable for treating wastewater containing organic matter and a wastewater treatment method using the same.

As a representative biological wastewater treatment method, activated sludge method has been commonly used. The activated sludge method is a wastewater treatment method applied for the second treatment of the first treated wastewater or to completely treat the wastewater that has not been subjected to the first treatment. . According to the general activated sludge method, as the waste water is continuously injected into the aeration tank, the microorganism grows by ingesting and decomposing organic matter in the wastewater and proceeding to nitrification. Part of is returned to the aeration tank in the form of activated sludge and some waste sludge is discarded, so that the amount of microorganisms in the aeration tank is maintained at an appropriate level, and nitrogen and phosphorus are removed along with decomposition of organic matter in the waste water.

This activated sludge method has long been recognized that it has an excellent effect in treating organic matter in wastewater, but it is not suitable for effective removal of organic matter and nitrogen from wastewater containing high concentrations of organic matter and nitrogen at the same time, and the amount of excess sludge increases. Have

As a result, numerous sewage treatment plants, manure treatment plants, livestock wastewater treatment plants, and industrial wastewater treatment plants are installed and operated nationwide, but most of them adopt conventional biological treatment methods based on activated sludge. Nutrients such as nitrogen and phosphorus are discharged in an almost untreated state.

Biological nitrogen and phosphorus removal methods include oxidative sphere method, activated sludge method, A / O (Anaerobic + Oxic) method, A ² / O (Anaerobic + Anoxic + Oxic) method, Badenpho method, UCT (University of Cape) Town (VIP) and Virgin Initiative Plant (VIP) processes are well known, and these technologies are evaluated to be capable of treating nitrogen and phosphorus at the same time without requiring more cost than conventional activated sludge. .

However, the understanding of biochemical theory and process design of the biological nitrogen and phosphorus treatment technology is not yet complete, and there is still much room for improvement in this respect. In other words, the conventional biological nitrogen and phosphorus treatment (BNR) method basically forms anaerobic (or anoxic) -aerobic conditions alternately, so that nitrification, denitrification and phosphorus release / overingestion of microorganisms are performed. It is a very economical and effective technology, but has the following fundamental limitations.

(1) Nitrification requires a large amount of oxygen (4.6g-O2 / g-NH4-N) and slows the growth rate of nitrifying microorganisms.

(2) To denitrate after nitrification, a large amount of organic matter (about 4g-BOD / g-NO ₃ -N) is required. This is a big problem when the BOD of sewage is low as in Korea.

(3) Denitrification microorganisms result in competition of phosphorus-releasing microorganisms with organics, inhibiting phosphorus release and lowering subsequent phosphorus excess intake efficiency.

(4) Long sludge retention time (SRT) is required for nitrification, but the longer the SRT, the lower the phosphorus removal efficiency.

On the other hand, ammonia nitrogen in the waste water is generally treated by a biological treatment method by a two-step process of nitrification-denitrification. That is, in the nitrification step, ammonia nitrogen is converted to nitric acid (NO ₃ -N) by aerobic nitrification bacteria.

However, in the case of wastewater treatment containing high concentrations of nitrogen, the growth rate of nitrifying microorganisms is relatively slower than that of organic matter removing microorganisms. Therefore, nitrification requires a long sludge residence time. It may spill out of the process.

In addition, in the denitrification process, the denitrification microorganism oxidizes the organic substance while reducing the nitrate nitrogen to nitrogen gas (N ₂ ) using the organic substance as an electron donor and releasing it into the atmosphere. Therefore, when organic matter is insufficient when reducing nitrate nitrogen in the denitrification process, there is a problem that the denitrification rate is lowered and the overall nitrogen removal rate is reduced.

Therefore, the technical problem to be achieved by the present invention is to contain wastewater having a low C (carbon) / N (nitrogen) ratio because it contains a high concentration of organic nitrogen and ammonia nitrogen to eliminate the problems of the conventional biological nitrogen treatment method described above. It is an object to provide a wastewater treatment apparatus capable of efficiently removing organic matter and nitrogen.

Another technical problem to be achieved by the present invention is to provide a wastewater treatment method which can efficiently remove organic matter and nitrogen for wastewater having a low C / N ratio because it contains a high concentration of organic nitrogen and ammonia nitrogen using the above apparatus. It is.

1 is a schematic view for explaining a wastewater treatment apparatus according to an aspect of the present invention.

2 is a schematic view for explaining a wastewater treatment method according to an embodiment of the present invention.

<Description of Major Reference Marks>

DESCRIPTION OF SYMBOLS 1: Anaerobic tank 3: 1st aeration tank 5: 2nd aeration tank

7: Stabilization tank 9: Settling tank 11: Internal conveying line

13: sludge conveying line

In order to achieve the above technical problem, the present invention is an oxygen-free tank in which a reaction to denitrify by introducing a denitrifying bacteria and organic matter in the waste water by introducing the waste water to be treated to reduce the nitrite nitrogen and nitrate nitrogen to nitrogen gas;

The first process in which the treated water passed through the oxygen-free tank is introduced, and the reaction of lowering the carbon / nitrogen ratio in the treated water is performed to oxidatively decompose the organic matter contained in the treated water using an aerobic microorganism to be suitable for subsequent partial nitrification reaction. Aeration tank;

The treated water passed through the first aeration tank is introduced, and the reaction of partially nitrifying the organic nitrogen and ammonia nitrogen in the treated water passed through the first aeration tank with nitrate nitrogen and nitrite nitrogen using ammonia oxidizing bacteria and nitrite oxidizing bacteria. An ongoing second aeration tank;

An internal conveying line for conveying a portion of the treated water that has passed through the second aeration tank to the anoxic tank;

The treated water that has passed through the second aeration tank flows in, and the step of immersing the sludge in the treated water and discharging the supernatant as the final treated water includes a settling tank; And

A sludge conveying line for conveying a portion of sludge in the settling tank to the anoxic tank provides a wastewater treatment apparatus.

Wastewater treatment apparatus according to the present invention is introduced into the treated water passed through the second aeration tank, the additional organic matter contained in the treated water is further oxidized by using aerobic microorganisms and the excess organic nitrogen and ammonia contained in the treated water The method may further include a stabilizer in which a reaction of partially nitrifying the nitrous nitrogen into nitrite nitrogen and nitrate nitrogen is performed.

In order to achieve the above another technical problem, the present invention also includes the step of introducing the waste water to be treated into an oxygen-free tank to denitrify by reducing the nitrite nitrogen and nitrate nitrogen to the nitrogen gas using denitrification bacteria and organic matter in the waste water;

Introducing the treated water that has undergone the anoxic tank into the first aeration tank to oxidize and decompose the organic matter contained in the treated water using an aerobic microorganism to reduce the carbon / nitrogen ratio of the treated water so as to be suitable for subsequent partial nitrification reactions; ;

The treated water having passed through the first aeration tank is introduced into a second aeration tank, and organic nitrogen and ammonia nitrogen in the treated water having passed through the first aeration tank are converted into nitrate nitrogen and nitrite nitrogen using ammonia oxidizing bacteria and nitrite oxidizing bacteria. Partially nitrifying and conveying a portion of the treated water that has passed through the second aeration tank to the anoxic tank; And

Flowing the treated water that has passed through the second aeration tank into the settling tank, submerging the sludge in the treated water and discharging the supernatant as final treated water, and returning a portion of the sludge in the settling tank to the anoxic tank. A wastewater treatment method is provided.

In the wastewater treatment method according to the present invention, the treated water having passed through the second aeration tank is introduced into a stable tank, and the extra organic matter contained in the treated water is further oxidatively decomposed using an aerobic microorganism, and is included in the treated water. The method may further include partially nitrifying the excess organic nitrogen and ammonia nitrogen with nitrite nitrogen and nitrate nitrogen, and then introducing the treated water into the precipitation tank.

In the wastewater treatment apparatus and wastewater treatment method according to the present invention, the aerobic microorganism of the first aeration tank is preferably attached to a polyurethane foam carrier coated with activated carbon powder.

In the wastewater treatment apparatus and wastewater treatment method according to the present invention, it is preferable that the volume of the polyurethane foam carrier is 5 to 30% by volume based on the volume of the first aeration tank.

In the wastewater treatment apparatus and wastewater treatment method according to the present invention, the ammonia oxide bacteria and the nitrite oxide bacteria in the second aeration tank are preferably attached to a polyvinyl alcohol foam carrier.

In the wastewater treatment apparatus and the wastewater treatment method according to the present invention, the volume of the polyvinyl alcohol carrier is preferably 5 to 30% by volume based on the volume of the second aeration tank.

In the wastewater treatment apparatus and wastewater treatment method according to the present invention, the carrier is preferably a fluidized bed carrier.

The wastewater treatment apparatus and the wastewater treatment method according to the present invention are distinguished from the removal of nitrogen components in the wastewater through the conventional nitrification-nitridation mechanism by complete nitrification. It is to remove the nitrogen component of.

In other words, according to the wastewater treatment apparatus and wastewater treatment method of the present invention, the activity of nitrifying microorganisms is controlled by adjusting the concentration of free ammonia (FA) and dissolved oxygen concentration of the molecular form (NH3), not the ion form (NH4 +). By suppressing the nitrification process can be terminated in the nitrite oxidation step can lead to the accumulation of nitrous nitrogen.

Therefore, the amount of oxygen required in the conversion from nitrite nitrogen to nitrate nitrogen is reduced, and since the conversion from nitrite nitrogen to nitrogen gas in the denitrification process, the organic matter required in the conversion process from nitrate nitrogen to nitrite nitrogen This is reduced and economical.

In other words, the existing nitrogen removal process (1) the nitrification process that requires a large amount of oxygen of NH4-N → NO2-N → NO3-N and (2) the organic material of NO3-N → NO2-N → N2O-N → N2 In contrast to the required denitrification process, the new short-nitrogen removal process of the present invention inhibits the action of nitrifying microorganisms and inhibits the conversion of NO2-N into NO3-N. Thus, (1) NH4-N → NO2-N (2) Denitrification process requires partial organic oxidation and (2) NO2-N → N2O-N → N2. Therefore, there is an economic advantage of reducing oxygen demand and organic matter requirement.

Hereinafter, with reference to the accompanying Figure 1 will be described in detail the wastewater treatment apparatus and treatment method according to the present invention.

As used herein, the term "wastewater" refers to wastewater to be treated using the apparatus of the present invention, which may or may not have been subjected to a pretreatment, for example, a primary settling basin. However, any one of the reaction vessels included in the apparatus of the present invention is excluded. The term "treated water" as used herein also means wastewater that has passed through one or more reactors contained in the apparatus of the present invention.

On the other hand, the nitrogen component in the waste water exists in the form of organic nitrogen and inorganic nitrogen, these are collectively called total nitrogen (TN). Inorganic nitrogen is again divided into ammonia nitrogen and nitrate nitrogen (NO _x ), and ammonia nitrogen and organic nitrogen are called TKN (Total Kjeldahl Nitrogen), and the nitrogen component referred to in the present invention means TKN.

1 is a schematic view of a wastewater treatment apparatus according to one embodiment of the present invention.

Referring to FIG. 1, a wastewater treatment apparatus according to an aspect of the present invention may include five biological biological components: an anaerobic tank (1), a first aeration tank (3), a second aeration tank (5), a stabilizer tank (7), and a settling tank (9). It consists of a reaction tank, the internal conveyance line 11, and the sludge conveyance line 13.

The anoxic tank 1, the first aeration tank 3, the second aeration tank 5 and the stabilization tank 7 may be composed of one reactor each, or may be composed of several stages by installing a partition in one reactor. . In addition, the size of the reaction tank can be adjusted according to the quality of the incoming wastewater and the quality of the treated water, and the stabilizer may be omitted.

The purpose and function of each reactor are as follows.

Oxygen-free tank (1) is to denitrify by reducing the nitrite nitrogen and nitrate nitrogen to the nitrogen gas by using the denitrification bacteria in the anoxic tank (1) and organic matter in the waste water in the anoxic condition by introducing the waste water to be treated. In addition to the waste water to be treated, the anaerobic tank 1 introduces a portion of the treated water that has passed through the second aeration tank 5 through the internal conveying line 11 and inflows sludge from the settling tank 9 through the sludge conveying line 13. have. Anoxic conditions mean that dissolved oxygen is not present in the wastewater, but chemically bound oxygen, such as nitrite nitrogen and nitrate nitrogen, is useful for microbial metabolism.

The first aeration tank 3 introduces treated water that has undergone the oxygen-free tank 1 to decompose organic matter contained in the treated water using aerobic microorganisms, thereby lowering carbon / nitrogen consumption in the treated water so as to be suitable for subsequent nitrification reactions. It is to let.

The second aeration tank (5) introduces the treated water which has undergone the organic decomposition reaction step in the first aeration tank (3), and converts nitrogen components in the treated water into nitrite nitrogen and nitrate nitrogen using ammonia oxidizing bacteria and nitrate bacteria. This is where the reaction proceeds. These microorganisms attach to the fluidized polyvinyl alcohol foam fluidized bed carrier to form a biofilm. At this time, a part of the treated water which passed through the 2nd aeration tank 5 is conveyed to the anoxic tank 1 through the internal conveyance line 11.

The stabilizer 7 flows in the treated water that has passed through the second aeration tank 5 to further oxidatively decompose the unprocessed excess organic matter in the first aeration tank 3 and the untreated organic nitrogen in the second aeration tank 5. And for further converting the ammonia nitrogen to nitrite nitrogen or nitrate nitrogen. However, as described above, the stabilizer tank is not necessarily required in the apparatus of the present invention, and a carrier is not added to the stabilizer tank.

The settling tank 9 introduces the treated water which has passed through the stabilization tank 7 to settle the sludge contained therein. Precipitation here refers to general solids separation, including filtration, centrifugation and the like. At this time, a part of the sludge settled at the bottom of the settling tank (9) can be conveyed to the anaerobic tank (1) through the sludge conveying line 13, whereby the amount of microorganisms in the anoxic tank can be maintained at an appropriate level.

Next, a wastewater treatment method according to one embodiment of the present invention will be described with reference to FIG. 2.

Referring to FIG. 2, first, an organic substance and a high concentration of nitrogen components are added to a wastewater having a low C / N ratio to an anoxic tank in which denitrifying bacteria live, and then a denitrification step 15 is performed. At this time, part of the treated water that has passed through the second aeration tank is returned to the oxygen-free tank. In an oxygen-free tank, oxidation of organic matter and reduction of nitrite nitrogen and nitrate nitrogen proceed simultaneously.

That is, organic matter in the influent wastewater acts as an electron donor in the denitrification reaction and is oxidized, and nitrite and nitrate nitrogen present in the influent wastewater and the return water from the second aeration tank are donated with electrons to provide nitrogen (N ₂ ). Reduction into gas removes organic matter and nitrogen components from the wastewater.

Subsequently, the organic matter removing reaction step 17 is performed in the first aeration tank. This is a step for removing untreated organics in the treated water after the anaerobic tank, when the wastewater containing a large amount of organic matter is introduced into the anaerobic tank because there is an excessive amount of organic matter compared to the nitrogen component to be denitrated.

That is, if the organic material is present in high concentration, the second aeration tank in which the subsequent nitrification step 19 is performed competes with each other to use the oxygen-limited oxygen-removing microorganisms (heterotrophs) and the nitrifying microorganisms (autotrophs) to reduce the nitrification rate. This may be a step to prevent this. This lowers the carbon / nitrogen ratio of the treated water that has passed through the first aeration tank to be suitable for subsequent nitrification.

This organic matter removal reaction step 17 is carried out by an aerobic microorganism attached to a polyurethane foam fluidized bed carrier coated with activated carbon powder in a first aeration tank. In addition, the microorganisms present in the suspended state in the first aeration tank also participates in the decomposition of organic matter, due to the action of the microorganisms attached to the carrier, even if the organic load fluctuation is large, stable water effluent can be obtained.

The volume of the fluidized bed polyurethane foam carrier is adjusted to account for 5-30% by volume based on the volume of the first aeration tank. If the input amount is less than 5% by volume, the amount of aerobic microorganisms is small, and the removal rate of organic matter is poor. If the amount is more than 30%, the amount of carrier is excessive, and the carrier is not easily circulated in the first aeration tank. This becomes bad.

Subsequently, a partial nitrification step 19 takes place. If there is a relatively low concentration of organic matter in the wastewater compared to the high concentration of nitrogen in the waste water, the denitrification rate is deteriorated overall, so the nitrogen removal rate is poor. Therefore, the partial nitrification step is a process for preventing this problem.

That is, the treated water with the carbon / nitrogen ratio controlled appropriately through the first aeration tank is introduced into a second aeration tank including a polyvinyl alcohol foam fluidized bed carrier having ammonia oxide bacteria and nitrite oxide bacteria attached thereto. Ammonia nitrogen is converted to nitrite nitrogen or nitrate nitrogen using ammonia oxidizing bacteria and nitrite oxidizing bacteria.

The polyvinyl alcohol foam fluidized bed carrier contains a large amount of hydroxyl group, which is a hydrophilic functional group, and is easily hydrated when contacted with water, so that ammonia oxidizing bacteria and nitrite oxidizing bacteria are easily attached to form a biofilm.

The volume of the polyvinyl alcohol foam carrier is adjusted to take up 5 to 30% by volume based on the volume of the second aeration tank. If the input amount is less than 5% by volume, the amount of microorganisms is low, so the nitrite oxidation rate and nitrification rate are poor. If the amount is more than 30%, the amount of the carrier becomes excessive, and the carrier is not easily circulated in the aeration tank. This is difficult.

In addition, a part of the treated water that has passed through the second aeration tank where the nitrification reaction occurs is returned to the oxygen-free tank. The purpose of the return is to remove nitrogen by denitrifying the nitrous and nitrate nitrogens converted in the aeration tank using organics in the influent wastewater under anoxic conditions.

On the other hand, the reaction occurring in the second aeration tank is referred to as partial nitrification or nitrous oxidation, in which part of the organic nitrogen and ammonia nitrogen are converted to nitrate nitrogen, and some are not completely oxidized to nitrate nitrogen, but nitrite It means that the oxidation step is terminated in the nitrogen phase. Due to such partial nitrification, a large amount of nitrite nitrogen is also present in the second aeration tank, for the following reasons.

That is, the biofilm formed on the surface of the fluidized bed carrier in the second aeration tank includes ammonia oxidizing bacteria (nitrosomonas genus) for converting ammonia nitrogen to nitrite nitrogen and nitrite oxidizing bacteria (nitrobacter genus) for converting nitrite nitrogen to nitrate nitrogen. This large amount exists, and because of the biofilm, the microorganisms causing these nitrification reactions are kept at high concentrations.

On the other hand, in the second aeration tank, if the ammonia nitrogen content is high and the pH is maintained high, FA (Free Ammonia) is present, which inhibits the activity of ammonia oxidizing bacteria and nitrite oxidizing bacteria. However, nitrite oxidizing bacteria are more sensitive to FA concentration than ammonia oxidizing bacteria, and when the FA concentration is increased, the conversion of nitrous nitrogen to nitrate nitrogen is suppressed, and eventually nitrite nitrogen accumulates.

In addition, ammonia and nitrite oxides are mixed in the biofilm formed on the carrier, but since dissolved oxygen in the second aeration tank is almost consumed at the surface of the biofilm, the nitrite oxide bacteria mainly inside the biofilm are almost inactive due to the lack of dissolved oxygen. It becomes impossible and becomes one of the other reasons which nitrite nitrogen accumulates.

Therefore, since the return water returned from the second aeration tank to the anoxic tank contains a large amount of nitrous nitrogen, in the anoxic tank, not only denitrification from nitrate nitrogen but also denitrification from nitrite nitrogen occurs. In case of denitrification from nitrite nitrogen, the process of conversion from nitrite nitrogen to nitrate nitrogen is omitted. Therefore, the amount of carbon source required is reduced by about 40% compared to the case of denitrification from the same amount of nitrate nitrogen. It is reduced by about 25%, which contains a high concentration of nitrogen, but contains a relatively low concentration of organic matter has a great advantage that can be more stable and economical treatment of low C / N ratio wastewater.

Subsequently, an additional organic removal reaction and an additional nitrification step are performed in the stabilizer (19).

That is, the treated water that has passed through the second aeration tank is introduced into the stabilizer tank to further oxidize and remove untreated organic matter contained in the treated water that has undergone the second aeration tank and further convert untreated ammonia nitrogen to nitrite nitrogen or nitrate nitrogen.

Subsequently, the sludge removing step 23 is performed. That is, the treated water that has passed through the stabilization tank is introduced into the settling tank, the sludge in the treated water that has passed through the stabilization tank is settled, and the supernatant is discharged as treated water that has been treated. On the other hand, part of the sludge settled in the settling tank is returned to the anoxic tank, and the remaining sludge is discharged and disposed of as excess sludge.

Hereinafter, the present invention will be described in more detail with reference to the following Examples, but it is obvious that the present invention is not limited by the following Examples.

<Example>

In this embodiment, the pilot plant according to the present invention having a treatment capacity of ³ m ³ per day was installed in a waste landfill wastewater treatment plant in Ansan-si, Gyeonggi-do, and operated for 8 months. In the pilot plant, the volume ratio of the anaerobic tank, the first aeration tank, and the second aeration tank is 1: 1: 1, and the first and second aeration tanks each consist of two stages with one partition. In the anoxic tank, denitrification bacteria are suspended at a concentration of 3000 mg / L. In the first aeration tank, a fluidized bed carrier for removing organic matter (manufacturer name: Samsung Engineering, trade name; BioCAP) and a second aeration tank for a nitrification fluidized bed carrier (manufacturing) Company name; Samsung Engineering, brand name; BioPOP) was added to 20% by volume based on the volume of the first and second aeration tanks, respectively.

Subsequently, the leachate was treated by introducing the leachate into the wastewater treatment device. The leachate was introduced into the wastewater treatment system, and the residual retention time was initially reduced to 15 days and finally increased to 1.3 days.

SCOD _Cr (Soluble Chemical Oxygen Demand) and nitrogen concentration of the treated water flowing out through the wastewater treatment system were measured and the removal rate of SCOD _Cr and nitrogen according to the change of residence time was calculated. In Table 1, Table 2, Table 3, all the experimental methods used in the measurement was in accordance with the standard process test method.

Table 1 summarizes the values obtained by measuring the concentrations of SCOD and nitrate nitrogen in the inflow water introduced into the wastewater treatment apparatus according to the present invention and the treated water treated in each reactor in the wastewater treatment apparatus.

[Table 1] Operation data for leachate treatment by partial nitrification

Influent Anaerobic First Aeration Tank (First Stage) First Aeration Tank (Second Stage) Second Aeration Tank (First Stage) Second Aeration Tank (Second Stage) Sedimentation tank Removal rate SCOD _cr (mg / ℓ) 5902 853 295 289 288 284 294 95% NH ₄ -N (mg / L) 581 164 21 18 18 17 23 96 Bounce rate Internal Transfer Rate = 1Q, Sludge Return Rate = 1Q SCOD _cr (mg / ℓ) 3322 704 409 391 389 378 409 88 NH ₄ -N (mg / L) 696 273 133 94 73 66 70 90 Bounce rate Internal Transfer Rate = 1Q, Sludge Return Rate = 1Q

SCOD _cr : Soluble Chemical Oxygen Demand measured by chromium method

NH ₄ -N: ammonia nitrogen

1Q: Means that the return from the second aeration tank to the anaerobic tank is equal to the amount of incoming wastewater.

[Table 2] Operation data for leachate treatment by complete nitrification

Influent Anaerobic Nitrification tank (2nd stage) Sedimentation tank SCOD _cr (mg / ℓ) 5,385 597 272 280 NO ₂ -N _r (mg / ℓ) 0 2 2 2 NO ₃ -N _r (mg / ℓ) 9 10 333 343

NO ₂ -N: nitrite nitrogen

[Table 3] Operation data for leachate treatment by partial nitrification

Influent Anaerobic Nitrification tank (2nd stage) Sedimentation tank SCOD _cr (mg / ℓ) 3322 704 378 409 NO ₂ -N _r (mg / ℓ) 0 2 122 111 NO ₃ -N _r (mg / ℓ) 8 10 135 132

The nitrite oxidation reaction in the present invention is due to the concentration of ammonia (NH4 ⁺ ) in the ionic form and free ammonia (FA: NH3) produced according to the pH. As shown in Tables 1 to 3, the complete nitrification reaction (NH4 → NO3) was predominant at the NH4 ⁺ -N concentration of 20 mg / L or less, and the nitrification was predominant at 60 mg / L or higher, resulting in the accumulation of NO2-N. It became.

Referring to the experimental results, it can be seen that for stable nitrous oxidation reaction (that is, accumulation of NO2-N), the concentration of NH4-N in the reactor should be maintained at least 60 mg / L and the pH should be maintained at about 7.5-8. have.

ΔSCOD _cr / ΔNO _X −N, which is a measure of the C / N ratio in the case of complete nitrification, is obtained from Equation 1 below. First, ΔSCODcr represents a change in dissolved chemical oxygen demand, and ΔNOX-N represents a change in nitrite nitrogen and nitrate nitrogen, respectively.

ΔSCOD _cr / ΔNO _X -N = [(5,385 + 272 + 280) Q-(597 × 3Q)] / [(9 + 335 + 345) Q-(12 × 3Q)] = 6.35

Table 3 shows the results of the leachate treatment in the partial nitrification method according to the present invention. From this, ΔSCOD _cr / ΔNO _X -N in the case of denitrification after partial nitrification is shown in Equation 2.

ΔSCOD _cr / ΔNO _X -N = [(3322 + 378 + 409) Q-(704 × 3Q)] / [(8 + 257 + 243) Q-(12 × 3Q)] = 4.23

Comparing the results of Equations 1 and 2, it was found that the ΔSCOD _cr / ΔNO _X -N value decreased by about 33.3% when the leachate was treated by denitrification after partial nitrification according to the wastewater treatment apparatus and wastewater treatment method of the present invention. This means that by removing the nitrogen in a denitrification manner after partial nitrification according to the present invention, the required amount of organic matter in the waste water can be reduced by about 33.3%.

As described above, the wastewater treatment apparatus and wastewater treatment method according to the present invention contain a high concentration of nitrogen components and can efficiently treat wastewater having a low C / N ratio.

That is, in the first aeration tank into which the organic material removing fluidized bed carrier is introduced, the organic matter is stably removed despite the organic load change of the influent, thereby minimizing the influence of the organic matter on the partial nitrification reaction in the second aeration tank, and the second aeration tank. The partial nitrification reaction in the formation of nitrite nitrogen and return to the anoxic tank can significantly increase the treatment rate of ammonia nitrogen.

Although the present invention has been described with reference to the embodiments, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent implementations are possible therefrom. For example, in the present invention, a fluidized bed carrier is used in the first and second aeration tanks, but a fixed bed carrier may be used. However, in the case of using a fixed bed, it is preferable to use a fluidized bed carrier because the thickness of the microbial membrane becomes anaerobic, causing the microorganism to be temporarily desorbed and the water quality tends to deteriorate rapidly. In particular, the activated carbon-coated polyurethane foam carrier used in the present invention exhibits superior characteristics in wastewater treatment compared to the case of using a conventional simple polyurethane carrier. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (14)

An anoxic tank in which a nitrate nitrogen and nitrate nitrogen are reduced to nitrogen gas and denitrification is carried out by introducing waste water to be treated and denitrifying bacteria and organic matter in the waste water; The first process in which the treated water passed through the oxygen-free tank is introduced, and the reaction of lowering the carbon / nitrogen ratio in the treated water is performed to oxidatively decompose the organic matter contained in the treated water using an aerobic microorganism to be suitable for subsequent partial nitrification reaction. Aeration tank; The treated water passed through the first aeration tank is introduced, and the reaction of partially nitrifying the organic nitrogen and ammonia nitrogen in the treated water passed through the first aeration tank with nitrate nitrogen and nitrite nitrogen using ammonia oxidizing bacteria and nitrite oxidizing bacteria. An ongoing second aeration tank; An internal conveying line for conveying a portion of the treated water that has passed through the second aeration tank to the anoxic tank; The treated water that has passed through the second aeration tank flows in, and the step of immersing the sludge in the treated water and discharging the supernatant as the final treated water includes a settling tank; And And a sludge conveying line for conveying a portion of the sludge in the settling tank to the anoxic tank. The wastewater treatment apparatus of claim 1, wherein the wastewater treatment device introduces the treated water that has passed through the second aeration tank, further oxidizes the excess organic matter contained in the treated water using an aerobic microorganism, and the excess organic matter included in the treated water. A wastewater treatment apparatus further comprising a stabilization tank in which a reaction for partially nitrifying nitrogen and ammonia nitrogen into nitrite nitrogen and nitrate nitrogen proceeds. The wastewater treatment apparatus according to claim 1, wherein the aerobic microorganisms of the first aeration tank are attached to a polyurethane foam carrier. The wastewater treatment apparatus of claim 3, wherein the volume of the polyurethane foam carrier is 5 to 30% by volume based on the volume of the first aeration tank. The wastewater treatment apparatus according to claim 1, wherein the nitrite oxidizing bacteria and the ammonia oxidizing bacteria of the second aeration tank are attached to a polyvinyl alcohol foam support. The wastewater treatment apparatus of claim 5, wherein the volume of the polyvinyl alcohol carrier comprises 5 to 30% by volume based on the volume of the second aeration tank. The wastewater treatment apparatus according to any one of claims 3 to 6, wherein the carrier is a fluidized bed carrier. Introducing the wastewater to be treated into an anaerobic tank to denitrify the nitrite nitrogen and the nitrate nitrogen with a nitrogen gas by using denitrifying bacteria and organic matter in the wastewater; Introducing the treated water that has undergone the anoxic tank into the first aeration tank to oxidize and decompose the organic matter contained in the treated water using an aerobic microorganism to reduce the carbon / nitrogen ratio of the treated water so as to be suitable for subsequent partial nitrification reactions; ; The treated water having passed through the first aeration tank is introduced into a second aeration tank, and organic nitrogen and ammonia nitrogen in the treated water having passed through the first aeration tank are converted into nitrate nitrogen and nitrite nitrogen using ammonia oxidizing bacteria and nitrite oxidizing bacteria. Partially nitrifying and conveying a portion of the treated water that has passed through the second aeration tank to the oxygen-free tank; And Flowing the treated water that has passed through the second aeration tank into the settling tank, soaking the sludge in the treated water and discharging the supernatant as the final treated water, and returning a portion of the sludge in the settling tank to the anoxic tank. Wastewater treatment method. The process of claim 8, wherein the treated water passed through the second aeration tank is introduced into the stabilizer tank, and the extra organic matter contained in the treated water is further oxidatively decomposed using an aerobic microorganism, and the excess organic nitrogen contained in the treated water. And partially nitrifying the ammonia nitrogen with the nitrite nitrogen and the nitrate nitrogen, and then introducing the treated water into the settling tank. The wastewater treatment method according to claim 8, wherein the aerobic microorganisms in the first aeration tank are attached to a polyurethane foam carrier. The method of claim 10, wherein the volume of the polyurethane foam carrier comprises 5 to 30% by volume based on the volume of the first aeration tank. The wastewater treatment method according to claim 8, wherein the ammonia oxide bacteria and the nitrite oxide bacteria of the second aeration tank are attached to a polyvinyl alcohol foam carrier. The method of claim 12, wherein the volume of the polyvinyl alcohol carrier comprises 5 to 30% by volume based on the volume of the second aeration tank. 14. The wastewater treatment method according to any one of claims 9 to 13, wherein the carrier is a fluidized bed carrier.