KR20070014857A - System and method for biological treatment of wastewater using mbr and zeolite powder - Google Patents

Abstract

A system and a method for biologically treating sewage/wastewater which maximize nitrification and denitrification by applying zeolite and membrane separation, maximize removal efficiency of organic matter and nitrogen using ion exchange of injected zeolite and biological regeneration thereof within a reactor, and are economical by allowing the zeolite to extend period of clogging the membrane of a membrane separation tank are provided. A system for treating sewage/wastewater comprises: an anoxic tank(2) into which a powder type zeolite is injected after calculating an injection quantity of zeolite according to concentration of ammonia nitrogen contained in sewage/wastewater flown in, and in which ammonia nitrogen is ion-exchanged with the injected powder type zeolite; a membrane separation tank(1) comprising a plurality of membranes(8) for solid-liquid separation of sludge and the ammonia nitrogen ion-exchanged powder type zeolite of the anoxic tank, and an aerator(10) installed under the membranes to accelerate the solid-liquid separation by the membranes; an oxidation tank(4) for decomposing the sludge that is solid-liquid separated in the membrane separation tank, thereby converting the sludge into dissolved organic matters; and an aeration tank(3) consistently regenerating the powder type zeolite transferred together with the sludge converted into the dissolved organic matters in the oxidation tank using nitrifying bacteria, thereby returning the regenerated powder type zeolite to the anoxic tank.

Description

TECHNICAL FIELD The present invention relates to a system and a method for treating wastewater using a zeolite and a membrane,

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing a treatment system for a wastewater according to the present invention using a zeolite and a membrane. Fig.

FIG. 2 is a diagram prepared for the calculation of the powdered zeolite dosage. FIG.

3 is a graph showing the removal rate of ammonia nitrogen of chemical wastewater by powder zeolite calculated and administered according to the present invention.

4 is a graph showing the removal rate of ammonia nitrogen in sewage water by powdery zeolite calculated and administered according to the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS (S)

1: membrane separation tank 2: anoxic tank

3: aerobic tank 4: oxidation tank

5: Return pump 6,10: Aeration device

7: Stirrer 8: Aeration device

9: Discharge pump

 The present invention relates to a method of administering a zeolite in an activated sludge treatment tank to improve the removal efficiency of nitrogen in the ion exchanged / waste water of excellent ammonia nitrogen of the applied zeolite while extending the service life of the membrane of the membrane separation tank .

Generally, most of the conventional sewage / wastewater treatment plants are operated with the activated sludge process, but these processes are mainly processes for removing organic matter, and they are currently used as a cause of eutrophication of lakes and marshes It is not suitable for the known removal process of nitrogen and phosphorus. Efforts to develop a new method that can replace this activated sludge process have been carried out in advanced countries. For example, the A / O method in which one anaerobic tank and one aerobic tank are arranged, a method of arranging two anaerobic tank and one aerobic tank Phosphorus A ² / O method, Phostrip method, Bardenpho method, and continuous batch method (SBR).

In recent years, membrane separation (MBR) processes using a membrane made of a material such as a hollow fiber membrane have been developed and applied in order to reduce microorganisms in the reaction tank and to reduce waste water pollutants. However, these processes have problems in that the removal efficiency is not high in the treatment of wastewater containing nitrogen at a high concentration, that there is a large amount of site required, or that the reactor is stably operated such as a membrane plugging phenomenon.

In order to solve such problems, for example, Korean Patent Publication Nos. 97-2624, 97-2628, 97-9650, 97-11327, 97-11330, 2001-0094714, The research results for biological wastewater treatment of bottom / wastewater have been proposed by applying the excellent selectivity of natural zeolite to ammonia, such as Japanese Patent Application No. 2003-0061720 and Japanese Patent Publication No. 10-99893.

Such conventional methods include a separate zeolite filter reactor or a zeolite regeneration tank installed on the outside so that raw water containing ammonia nitrogen or feed water containing treated water, microorganisms of nitrification tank, zeolite regenerated water, Or a mixture of raw water and a nitrifying tank are sent to a zeolite reaction tank to induce adsorption and nitrification in the zeolite reaction tank, or ammonia concentration When the adsorption of ammonia by zeolite is saturated, a material such as sodium chloride is used for the regeneration of the zeolite, or the microorganisms in the biological treatment tank are returned to regenerate the zeolite.

However, in the case of the above-described conventional methods, additional zeolite filter reaction tanks or zeolite regeneration tanks are required, and the burden of chemicals and the like on the artificial regeneration of ammonia-adsorbed zeolite, stagnation phenomena in the zeolite tanks And the like may occur.

Therefore, the inventors of the present invention have made efforts to solve the above-mentioned problems in the prior art, and have found that it is possible to replace the conventional activated sludge process with a simple flow path, to replace the settling tank with a membrane separation tank and to introduce only a small amount of powdery zeolite into a low concentration, In order to provide a biological treatment process for the new bottom / wastewater treatment which can increase the treatment efficiency, a certain amount of powdered zeolite is put into a series of biological treatment tanks in the order of aerobic tank, anoxic tank and membrane separation tank, The powdery zeolite and the sludge are allowed to perform biological COD reduction, heavy metal adsorption, denitrification, and dephosphorization through the respective reaction vessels, and subsequently the powdery zeolite is conveyed together with the sludge, To develop an economical biological sewage / wastewater treatment process It was.

It is an object of the present invention to maximize nitrification and denitrification by applying membrane separation between zeolite and membrane, maximize the removal efficiency of organic matter and nitrogen by using ion exchange of introduced zeolite and biological regeneration in the reactor, And to provide an economical biological bottom / wastewater treatment system and method that prolongs the clogging period of the membrane of the separation tank.

According to one aspect of the present invention, the above-mentioned object is achieved by a method of treating a zeolite powder in which powdered zeolite is dosed according to the concentration of ammonia nitrogen in the incoming bottom / wastewater, Exchanged anoxic tank; A plurality of membranes are provided for solid-liquid separation of powdery zeolite in which ammonia nitrogen is ion-exchanged in the anoxic tank, and a membrane separation tank in which aeration unit is installed in the lower part of the membrane to promote solid- ; An oxidation tank for decomposing the solid-liquid separated sludge in the membrane separation tank into dissolved organic matters; And an aerobic tank for continuously returning the powdered zeolite transferred together with the sludge converted from the oxidation tank to the dissolved organic matter using the nitrifying microorganism and returning the powdered zeolite to the anoxic tank. Can be achieved.

The above object can also be achieved according to another aspect of the present invention by administering powdered zeolite according to the dose calculated according to the concentration of ammonia nitrogen in the incoming bottom / wastewater, Ion exchanging nitrogen; Separating the powdery zeolite ion exchanged with ammonia nitrogen using a plurality of membranes and the sludge; Decomposing the solid-liquid separated sludge by the membranes into a soluble organic material; Continuously regenerating the powdered zeolite transferred with the sludge converted into dissolved organic matter so as to re-ionize the ammonia nitrogen in the incoming bottom / wastewater, and returning it to the nitrogen ion exchange step The waste water treatment method according to claim 1,

The powdery zeolite to be administered to the anoxic tank is estimated by the following isothermal adsorption formula:

Q ⁰ : Maximum absorption capacity

b: experimental coefficient

M: Weight of zeolite in anoxic tank

N _Z = (C _ea - C _eq ) x V _a

N _Z : Amount of ammonia nitrogen ion-exchanged to zeolite

C _eq : Equilibrium value of ammonia nitrogen concentration in anoxic tank

V _a : volume of anoxic tank (L 3)

N _O : Amount of ammonia nitrogen input

V: Amount of raw water inflow

V _I : Internal return amount

V _RAS : sludge return volume

In the above, the regeneration of the ammonia-nitrogen-exchanged zeolite is carried out through a nitrification mechanism by nitrifying bacteria that adhere to / grow on the zeolite in the aerobic tank.

In addition, the zeolite recovered by the biological mechanism in the aerobic tank is transferred with the sludge to the anoxic tank, and the re-ion exchange of the ammonia nitrogen of the influent water is repeated.

The above-mentioned powdered zeolite includes natural zeolite and synthetic zeolite having ion exchange capacity with respect to ammonia nitrogen.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the present invention relates to an anoxic tank (2, denitrification tank), an aerobic tank (3, nitrification tank), a membrane separation tank (1, solid-liquid separation tank), and an auxiliary facility for transporting sludge and zeolite and oxidizing sludge In the biological treatment / wastewater treatment process, a certain amount of powdery zeolite is preferably added to the anoxic tank 2, and the powdery zeolite is moved to the powdery zeolite 2 in the anoxic tank 2, (3) adsorbs ammonia nitrogen by adsorbed ammonia nitrogen, and the organic matter is reduced by microorganisms which are adhered to or suspended in the powdered zeolite. In the aerobic tank (3), the zeolite adsorbed by ammonia nitrogen is regenerated by nitrifying microorganisms. , That is, the powdered zeolite administered to the anoxic tank (2), changes the shear stress of the membrane (8) of the membrane separation tank (1) To prevent clogging of the membrane (8) by the sludge, and / it is possible to obtain a high treatment efficiency in waste water treatment, a method to reduce the site and reduce operating costs.

As shown in FIG. 1, the bottom / wastewater treatment system for carrying out the bottom / wastewater treatment method of the present invention comprises an aerobic tank 2 in which an aeration device 6 is installed at the bottom, a stirrer 7 rotated by a motor An anoxic tank 2 in which an anoxic tank 2 is installed and a plurality of membranes 8 for solid-liquid separation are installed and the aeration device 10 is installed below the sludge and zeolite powder adsorbed on the membrane 8, And the sludge solid-liquid separated from the membrane separation tank 1 is decomposed and converted into dissolved organic matter, and the sludge converted into the soluble organic matter is oxidized for transferring the sludge together with the zeolite to the oxic tank 3 (4).

The raw water to be treated (raw / waste water) is introduced into the anoxic tank 2 to which the powdered zeolite is applied, and the ammonia nitrogen in the raw water is ion-exchanged with the powdered zeolite administered to the anoxic tank 2 in the anoxic tank 2, Nitrogen is removed. At this time, the operation of the agitator 7 provided in the anoxic tank 2 facilitates ion exchange with ammonia nitrogen into zeolite. The powdery zeolite administered to the anoxic tank 2 is administered by a constant amount by an isothermal adsorption (Langmuir isotherm) determined according to the ammonia nitrogen concentration of the bottom / wastewater flowing into the anoxic tank 2, Nitrogen exchanges with cations such as Na ⁺ in zeolite under anaerobic conditions.

The zeolite ion-exchanged with ammonia nitrogen in the anoxic tank (2) is transferred to the membrane separation tank (1) together with raw water subjected to the denitrification treatment in the anoxic tank (2). The raw water transferred to the membrane separation tank 1 is subjected to solid-liquid separation through a membrane (separation membrane) 8 provided in the membrane separation tank 1. The wastewater subjected to solid-liquid separation in the membrane separation tank (1) is discharged to the outside by a discharge pump (9) connected to the membrane (8). At this time, the sludge and zeolite powder adsorbed on the surface of the membrane 8 are aerated by the aeration device 10 provided below the membrane separation tank 1 and separated from the membrane 8 to be separated from the membrane 8 And is conveyed from the membrane separation tank 1 to the oxidation tank 4 in the form of sludge by the operation of the transfer pump 5. [

As described above, in the membrane separation tank 1, the ammonia-nitrogen-exchanged zeolite and the sludge are introduced into the oxidation tank 4 by the transfer pump 5 connected to the membrane separation tank 1. In the oxidation tank 4, the sludge is decomposed and converted into dissolved organic matter, and the sludge converted into dissolved organic matter is transferred to the oxic tank 3 together with the zeolite. The zeolite transferred to the aerobic tank 3 together with the sludge is converted into nitrate nitrogen by continuously desorbing and regenerating the ammonia nitrogen into the solution phase as the equilibrium of the ammonia nitrogen ion is broken by the nitrification reaction.

As shown in FIG. 1, the regenerated zeolite and the nitrate nitrogen are transferred to the anoxic tank 2 again, and the nitrate nitrogen is reduced and removed by N ₂ gas by the denitrification reaction by the denitrifying bacteria using the organic matter of the influent raw water At the same time, the ammonia nitrogen of the incoming feed water is re-ion-exchanged with the regenerated zeolite. Separately, as the sludge is overgrown, the sludge is discarded when it is necessary to maintain proper microbial concentration.

At the same time, the ammonia nitrogen desorbed into the solution phase by the nitrification mechanism under aerobic conditions is converted into nitrate nitrogen, and is removed as nitrogen gas by the denitrification under the anaerobic condition. The introduced organic matter is consumed as the carbon source of the denitrification reaction, At this time, the reaction time can be appropriately changed depending on the nitrogen concentration and the microorganism concentration in the anoxic tank 2.

According to the present invention, as the solid-liquid separation by the membrane separation tank (1) is introduced into the bottom / wastewater treatment system, the reaction time is minimized by maximizing the microbial concentration. In the conventional process, the re-aeration in which the air is supplied for a short period of time for removing the organic matters consumed in the denitrification and the removal of the remaining organic substances and the degassing of the nitrogen gas is required to improve the settling property. However, in the process according to the present invention, As the solid-liquid separation is carried out, such re-aeration operation can be eliminated.

On the other hand, when operated in a conventionally known manner, ammonia nitrogen ion-exchanged with powdered zeolite is desorbed into a solution phase in an aerobic condition and converted into nitrate nitrogen, then discharged through the precipitation step together with the effluent, It is technically very difficult to obtain a treatment efficiency, that is, a nitrogen removal efficiency of about 60 to 70% or more. In addition, at least three separate reaction vessels are required in order to obtain a high nitrogen removal efficiency in the treatment process separated by the aerobic tank, the anoxic tank and the settling tank, and the transportation cost must be increased. In addition, / In the case of wastewater, there is a problem of sludge flooding in sedimentation basins and the potential for release of residual organic matter.

However, the method of treating wastewater according to the present invention can remove additional nitrogen by zeolite administered to a certain amount of anoxic tank 2 by an isothermal adsorption method irrespective of the transporting rate, and can use a membrane separation tank 1 instead of a conventional precipitation tank The reaction time can be shortened as much as possible, and the loss of zeolite and sludge can be effectively prevented. In addition to the function of enhancing the nitrogen removal efficiency, the applied zeolite also functions to contact the surface of the membrane 8 in the membrane separation tank 1 to cause shear stress to prevent the membrane 8 from clogging.

The powdered zeolite which can be used in the process of the present invention is preferably of any form capable of exchanging ammoniacal nitrogen and comprises natural zeolite and synthetic zeolite.

On the other hand, the amount of sludge to be discarded in the form of waste sludge is constantly discarded according to the sludge residence time (SRT) of the whole reaction tank. Therefore, a new powdered zeolite contained in the discarded sludge as much as the amount of powdered zeolite to be discarded together with the waste sludge must be replenished with the anoxic tank (2). The amount of the powdered zeolite to be supplemented is very small compared with the conventional method using the ion exchange column and may not be supplemented depending on the case. This is because the excess sludge of the low concentration / wastewater is treated by the ozone oxidation, electrolysis, It is preferable that a certain amount of powdered zeolite is supplied to the reaction tank, i.e., the anoxic tank 2, through an appropriate zeolite supply device to the outside when the excess sludge is discarded.

An important part of the present invention is the estimation of zeolite dose. Thus, a method for estimating the dosage of zeolite for nitrogen removal in the process of the present invention has been devised. For calculation of the powder type zeolite dosage, a mass balance was prepared as shown in Fig.

As shown in FIG. 2, the mass of ammonia nitrogen can be expressed by separating into a biological part and an ion exchange part. The effluent concentration (C _ea ) for removal of biological nitrogen by the recycle cost is shown in Equation 1.

----------------------------(1)

----------------------------(One)

Where N _O is the amount (M) of ammonia nitrogen introduced,

           V: Raw water inflow (L3)

V _I : the inner carry amount (L3)

V _RAS : sludge return amount (L3)

The ammonia nitrogen concentration of the anoxic tank 2 maintains a constant value of C _ea when a steady state is established in the absence of zeolite in the anoxic tank 2. In this state, when the zeolite is added to the anoxic tank 2, the ion exchange of the powdery zeolite with the ammonia nitrogen is performed as described above in the anoxic tank 2, and the ammonia nitrogen is removed by ion exchange . The powdered zeolite always maintains a constant concentration depending on the amount administered to the anoxic tank (2), and is not related to the return rate.

Therefore, the amount of ammonia nitrogen removed by the zeolite in the anoxic tank 2 can be expressed as shown in Equation (2). This equation shows that the concentration balance due to the ammonia nitrogen concentration (C _ea ) of the anoxic tank (2) and the amount of zeolite present in the anoxic tank (2) by the return ratio is always performed.

N _Z = (C _ea - C _eq ) x V _a - (2)

Where N _Z is the amount (M) of ammonia nitrogen ion-exchanged with zeolite,

C _eq : Equilibrium value of ammonia nitrogen concentration in anoxic tank (ML-3)

V _a : volume of anoxic tank (L 3)

N _Z is determined solely by the concentration of initial NH ₄ ⁺ -N (dilution concentration by transport) and the amount of zeolite in the anoxic tank 2, and the dilution effect by the transport is determined by C _ea of the anoxic tank 2 And ultimately affects the C _eq .

The concentration of ammonia nitrogen ion-exchanged by the zeolite in the anoxic tank (2) can be expressed as Equation (3).

----------------------------------(3)

---------------------------------- (3)

Therefore, the ammonia nitrogen concentration C _eff of the final effluent from the membrane separation tank 1 after ion-exchanged by the zeolite in the anoxic tank 2 can be expressed by Equation (4).

C _eff = C _ea - N _Z / V _a = C _eq --------------------------------(4)

Isothermal adsorption was applied to obtain the equilibrium concentration C _eq of ammonia nitrogen after ion exchange with zeolite in the anoxic tank (2).

---------------------------------(5)

--------------------------------- (5)

Here, M is the weight of the zeolite in the anoxic tank

Q ⁰ : Maximum absorption capacity

         b: experimental value

Equation 5 is applied to the Zeo-MBR process.

b C _eq ² + (1 + abC _z -bC _ea ) C _eq -C _ea = 0 - (6)

Substituting the coefficients of each term in Equation 7, we can summarize as follows.

xC _eq ² + yC _eq + z = 0 (7)

Here, x = b

y = 1 + Q ^{0 b C} _z -bC _ea

z = -C _e

Solving the equation 7 using the formula of the muscle can be determined as follows: C _eq.

------------------------------(8)

------------------------------(8)

The dose of zeolite can be estimated using the above equation.

Below. Preferred embodiments of the present invention will be described. However, the following examples are only for the understanding of the present invention, and the present invention is not limited to the following examples.

[Example]

1. Results of actual wastewater application

According to the method of the present invention, a total of 30 L acrylic reactor was used, and the recycle ratio was 1Q (100%). As a raw / wastewater sample, domestic wastewater (total nitrogen amount: 150 mg / L) and ammonium sulfate (total nitrogen amount: 50 mg / L) of domestic S company containing high concentration of ammonia nitrogen were used. Domestic products were purchased and powdered zeolite with a diameter of 100 ㎛ or less was applied and there was no supplementation of zeolite during the experiment. The hydraulic retention time (HRT) for the reaction group was about 24 hours in anoxic tank 2, about 48 hours in aerobic tank 3, and about 12 hours in membrane separation tank 1. Mixed Liquor Suspended Solids Loading ) Was about 5,000 ~ 7,000 mg / L, and the experiment was conducted for about 3 months. The wastewater was operated for about 2 hours in the anaerobic tank 2, about 3.5 hours in the aerobic tank 3, and about 1 hour in the membrane separation tank 1. The MLSS was 5,000 to 7,000 mg / L and the zeolite concentration was 5 g / Administration for about 3 months.

Experimental results showed that total nitrogen removal efficiency was 85% in case of chemical wastewater and 90% in case of wastewater. The experimental results are summarized in Table 1 below.

 division Ammonia nitrogen (NH ₄ ⁺ -N) Total nitrogen (T-N) Chemical oxygen demand (CODcr) Total (T-P) Suspended substance (SS) Chemical wastewater Influent (mg / L) 110 150 1,000 15 140 Effluent (mg / L) 20 25 35 3 One Removal rate (%) 82 83 97 80 99 Seawater Influent (mg / L) 45 50 200 5 100 Effluent (mg / L) 5 7 10 2 One Removal rate (%) 89 86 97 60 99

On the other hand, according to the present invention, the zeolite dose calculation result is as follows.

By applying an isothermal adsorption-type targeting S's chemical waste water it was carried out to obtain a simulated value of Q ⁰ and b. From the simulation results, it was found that the concentration of zeolite should be maintained at about 10,000 mg / L as shown in FIG. 3 in order to obtain a nitrogen removal efficiency of 80% at a recycle ratio of 1Q.

In addition, the Q ⁰ and b values of the isothermal adsorption equations obtained by the ion exchange experiments of the sewage generated in the sewage treatment plant were applied to investigate the removal efficiencies according to the dose and return rate of zeolite to S university sewage.

From the simulation results, it was found that the concentration of zeolite should be maintained at about 4,000 mg / L as shown in FIG. 4 in order to obtain a nitrogen removal efficiency of 80%.

As described above, the nitrogen-containing bottom / wastewater treatment method incorporating the membrane separation method according to the present invention as compared with the conventional biological treatment method not only shortens the reaction time for biological lowering / wastewater treatment, , In applying zeolite to the treatment of nitrogen-containing wastewater, it is possible to regenerate the zeolite biologically without the need for additional regenerating and regenerating chemicals, thereby increasing the nitrogen removal efficiency and preventing clogging of the membranes of the membrane separation tank, / Waste water.

Claims (10)

Anoxic tank in which the dosage is calculated according to the concentration of ammonia nitrogen in the incoming bottom / wastewater and the powdery zeolite is administered, and the ammonia nitrogen is ion-exchanged in the powdery zeolite administered; A plurality of membranes are provided for solid-liquid separation of the powdery zeolite in which ammonia nitrogen is ion-exchanged in the anoxic tank and the sludge is separated from the sludge, and a membrane separation tank in which aeration unit is installed in the lower part of the membrane to promote solid- ; An oxidation tank for decomposing the solid-liquid separated sludge in the membrane separation tank into dissolved organic matters; And And an aerobic tank for continuously returning the powdery zeolite transferred together with the sludge converted from the oxidation tank to the dissolved organic matter by using the nitrifying microorganism and returning the powdery zeolite to the anoxic tank. The waste water treatment system according to claim 1, wherein the powdered zeolite to be fed to the reaction tank is estimated by the following isothermal adsorption formula.

Q ⁰ : Maximum absorption capacity b: experimental value M: Weight of zeolite in anoxic tank N _Z = (C _ea - C _eq ) x V _a N _Z : Amount of ammonia nitrogen ion-exchanged to zeolite C _eq : Equilibrium value of ammonia nitrogen concentration in anoxic tank V _a : volume of anoxic tank (L 3)

N _O : Amount of ammonia nitrogen input V: Amount of raw water inflow V _I : Internal return amount V _RAS : sludge return volume The system of claim 1, wherein the regeneration of the ammonia-nitrogen-exchanged zeolite is accomplished through a nitrification mechanism by nitrifying bacteria that adhere to / grow on the zeolite in the aerobic basin. 4. The process according to claim 1 or 3, characterized in that the zeolite regenerated by the biological mechanism in the aerobic basin is transported together with the sludge to the anoxic tank and the re-ion exchange of the ammonia nitrogen of the influent raw water is repeated. system. The system of any one of claims 1 to 3, wherein said powdered zeolite comprises natural zeolite and synthetic zeolite having ion exchange capacity for ammonia nitrogen. Administering powdered zeolite according to the dose calculated according to the concentration of ammonia nitrogen in the incoming bottom / wastewater, thereby ion-exchanging the ammonia nitrogen in the applied powdered zeolite; Separating the powdery zeolite ion exchanged with ammonia nitrogen using a plurality of membranes and the sludge; Decomposing the solid-liquid separated sludge by the membranes into a soluble organic material; Continuously regenerating the powdered zeolite transferred with the sludge converted into dissolved organic matter so as to re-ionize the ammonia nitrogen in the incoming bottom / wastewater, and returning it to the nitrogen ion exchange step Wherein the bottom / wastewater treatment method comprises the steps of: The method according to claim 6, wherein the powdery zeolite to be added to the reaction tank is calculated by the following isothermal adsorption equation.

Q ⁰ : Maximum absorption capacity b: experimental value M: Weight of zeolite in anoxic tank N _Z = (C _ea - C _eq ) x V _a N _Z : Amount of ammonia nitrogen ion-exchanged to zeolite C _eq : Equilibrium value of ammonia nitrogen concentration in anoxic tank V _a : volume of anoxic tank (L 3)

N _O : Amount of ammonia nitrogen input V: Amount of raw water inflow V _I : Internal return amount V _RAS : sludge return volume 7. The method according to claim 6, wherein the regeneration of the ammonia-nitrogen-exchanged zeolite is carried out through a nitrification mechanism by nitrifying bacteria that attach / float to the zeolite in the aerobic basin. 9. The method according to claim 6 or claim 8, characterized in that the zeolite recovered by the biological mechanism in the aerobic basin is transported together with the sludge to the anoxic tank and the re-ion exchange of the ammonia nitrogen of the influent water is repeated. Processing method. 9. A method according to any one of claims 6 to 8, wherein the powdered zeolite comprises natural zeolite and synthetic zeolite having ion exchange capacity with respect to ammonia nitrogen.

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