JPH10165985A - Method for treating nitrogen-containing organic waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To treat nitrogen-contg. org. waste water in a short time by means of a compact apparatus by a method wherein nitrogen-contg. org. waste water is treated by using activated sludge-immobilized carrier prepd. by a method wherein the carrier is stuck with activated sludge and then, after it is treated with paste, it is cured. SOLUTION: In nitrification and denitrification treatment, a fluidized bed of activated sludge-immobilized carrier prepd. by artificial granulation is utilized and the activated sludge-immobilized carrier is prepd. by a method wherein at first, the carrier is stuck with activated sludge and then, after it is treated with a paste, it is cured. As this carrier, a carrier with a large specific gravity, e.g. sand, clay mineral, etc., and/or porous glass, etc., are used so as to settle in waste water and the size and the shape of the carrier to be used is appropriately selected in accordance with necessity. In addition, on putting it in practice, both nitrification and denitrification can be performed in one bio-treatment tank by storing the activated sludge-immobilized carrier in the bio-treatment tank and performing nitrification reaction of the waste water in the lower part and denitrification reaction in the upper part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitrification and denitrification treatment using an artificially granulated activated sludge-immobilized carrier. The present invention relates to the efficiency of organic wastewater containing nitrogen such as sewage. Useful for strategic processing.

[0002]

2. Description of the Related Art Conventionally, as biological nitrification denitrification method,
A circulation type nitrification denitrification method using floating activated sludge is known. The flow sheet is as shown in FIG. 1. First, raw water is separated into solid and liquid in a previous stage, and then enters a biological reaction tank. The biological reaction tank is composed of a nitrification tank (aerobic tank) and a denitrification tank (oxygen-free tank). In the nitrification tank, the nitrifying bacteria in the sludge oxidize ammonia nitrogen and the like in the raw water to oxidized nitrogen. Nitrification liquid is supplied from the nitrification tank outlet.
Circulated to the denitrification tank. In the denitrification tank, BOD in sewage
Then, the oxidized nitrogen in the circulating liquid reacts in an oxygen-free state to form nitrogen gas, and nitrogen is removed. The mixed solution that has exited the biological reaction tank is subjected to solid-liquid separation in a final sedimentation tank to obtain treated water. The sludge concentration required for the reaction is ensured by the sludge returned from the final settling tank.

[0003] Although the conventional method is excellent as a nitrification denitrification method, it is difficult to treat actual wastewater.
It is still not enough, and there is room for improvement.

That is, in the conventional method, the activated sludge concentration in the reaction tank cannot be increased, so that a long time is required for the treatment and the capacity of the treatment tank must be increased. In addition, the solid-liquid separation must be performed by separately providing a sedimentation tank, and at that time, the separation performance may be deteriorated depending on the operation state of the reaction tank, and maintenance is not easy.

[0005]

SUMMARY OF THE INVENTION The present invention has been developed to improve the above-mentioned inadequacy of the conventional method and to develop a new and useful nitrification and denitrification method, whereby the organic wastewater containing nitrogen can be efficiently removed. This was done to establish a new processing system.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and as a result of examination from various fields, it has been found that the activated sludge-immobilized carrier fluidized bed by artificial granulation has a high sludge concentration. Not only does it maintain and very efficiently perform nitrification and denitrification, but there is no need to separately install a solid-liquid separator,
It has been found that a compact apparatus can treat nitrogen-containing organic wastewater in a short period of time, and based on this useful new finding, further research has been completed. Hereinafter, the present invention will be described in detail.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the nitrification denitrification method according to the present invention, an activated sludge-immobilized carrier fluidized bed by artificial granulation is used. First, the activated sludge-immobilized carrier adheres activated sludge to the carrier. Then, this is treated with a paste, and then cured to produce the product.

In producing the activated sludge-immobilized carrier,
As the carrier, a carrier having a large specific gravity is used so as to be able to settle in wastewater. For example, sand, quartz sand, shell fossil, cristobalite, clay mineral (montmorillonite, bentonite,
Acid clay, kaolinite, etc.), iron powder, and / or porous glass. The size and shape of the carrier to be used are appropriately selected as necessary, and can be formed into a sphere, a rod, a square, a hollow, a film, a tube, a hollow fiber, or the like. The surface may be a smooth surface, a rough surface for improving adhesion, or a porous surface. In the case of small sphere, its particle size is 0.001-10mm
(Preferably about 0.05 to 0.3 mm).

In the present invention, when the carrier is charged with a cation or an anion, the adhesion of sludge is improved. Therefore, the charging method is a recommended method. For example, when the carrier is charged with a cation, the carrier has a molecular weight of 5 to 15,000,000 (preferably 1000 to 10,000,000).
Cationic polymer flocculants (eg, polydialkylaminoalkyl (meth) acrylate, polydialkylaminoalkyl (meth) acrylate-polyacrylamide copolymer, polyethyleneimine, chitosan, polyvinylpyridine hydrochloride, vinylpyridine copolymer salt) Etc.).

When the carrier is treated with the cationic polymer flocculant as described above, the carrier is directly cationized. However, when the cation-treated carrier is dried or treated without drying with an anionic polymer flocculant, not only is it cationized, but also both react to form a water-insoluble fibrous precipitate on the carrier surface. Therefore, such processing can also be used. In this way, if necessary, the carrier can be charged cationically as a whole by repeating the treatment of the cationic and anionic polymer flocculants a number of times, and the activated sludge is further strengthened by the fibrous matter produced. It can also be fixed and fixed.

These polymer flocculants may be treated alternately in layers as described above, or the carrier may be treated simultaneously with them to mix cations and anions on the surface of the carrier. Good. However, when a cationic polymer flocculant and an anionic polymer flocculant are used in combination, the ratio of use must be adjusted so that the chargeability becomes cation as a whole after the combined use.

As the anionic polymer coagulant, a molecular weight of 5 to 15,000,000 (preferably 1,000 to 15,000,000)
Anionic polymer coagulant (e.g., polyacrylate, poly (acrylamide-acrylate) copolymer,
Sodium alginate, maleic acid copolymer salt, etc.) are used.

The carrier thus treated with cations is
By contacting with activated sludge, the sludge adheres and aggregates on the carrier. In this case, since the carrier is treated with cation,
Adhesion and aggregation of sludge are promoted and strengthened as compared with the case of no treatment.

When the sludge is attached to the cation-treated carrier, the untreated sludge may be brought into contact with the carrier as described above.
Very good results can be obtained by contacting the carrier with a cation-treated carrier thereafter. (When charging the carrier, conversely, when the anion treatment is performed, the sludge is subjected to the cation treatment.) .

In the present invention, in order to more effectively combine the carrier and the activated sludge, not only the cationization of the carrier but also an entirely new technique of anionizing the activated sludge is employed. Technology is used together. The anionization of activated sludge is carried out by mixing and contacting an anion source with sludge, treating with an ion-exchange resin, or contacting with the above-described anionic polymer flocculant. It can be carried out as needed.

These polymer coagulants are used as aqueous solutions (0.05 to 5, preferably 0.1 to 1.0 w / v%).
Alternatively, the carrier can be cationized by making it into a paste or powder and bringing it into contact with the carrier (mixing stirring, spraying, etc.). The ratio of the carrier and the cationic (anionic) polymer flocculant is 100: 0.2 to 10 in terms of dry matter.
It is better to be about 0: 2.

The carrier charged with cations is charged into an anionized activated sludge as described above, or conversely, an anionized activated sludge is added to the carrier and the two are brought into contact with each other to treat the activated sludge. Is completed, and the activated sludge adheres to the carrier.

The anionization of the activated sludge is carried out by the above-mentioned method. For example, when the anionization is performed using an anionic polymer flocculant, about 0.01 to 10% of the anionic polymer flocculant is used. Adjust the aqueous solution of
If this is mixed with the activated sludge, the anionization is easily completed.

The carrier to which the sludge has been attached in this manner can be immediately subjected to a paste treatment described later.
However, if the following charging treatment is performed before the paste treatment, the effect is further enhanced. That is, the activated sludge-adhering carrier obtained as described above is anion-treated to further reinforce and reinforce the adhesion of sludge, and then subjected to cation-treatment. Alternatively, the cation and anion treatments can be performed simultaneously to slightly cationize. In any case, these processes can be performed in the same manner as described above.

Thereafter, the paste treatment is performed as follows. As the paste, for example, propylene glycol alginate, calcium cellulose glycolate, sodium, sodium starch glycolate, sodium starch phosphate, methylcellulose, sodium polyacrylate, gelatin, sodium caseinate,
Any type such as agar which can thicken, harden, and solidify alone without special treatment, or a type which is oxidized or gelled by metal ions or other hardeners can be used as appropriate.

Examples of the latter type are as follows (in parentheses, examples of curing agents): sodium alginate (metal ion): casein (calcium oxide, calcium hydroxide, sodium hydroxide, sodium fluoride, water) Glass); polyvinyl alcohol (ammonium sulfate, sodium sulfate + zinc sulfate) and others.

The sizing treatment is performed by adding an aqueous solution of the sizing agent and stirring or spraying the mixture to bring the sludge-adhering carrier into contact with the sizing agent, or adding a hardening agent.
Further, an aqueous solution of a curing agent may be added, or the treatment may be appropriately performed according to a conventional method. As a rough guide, the amount of the paste added is about 0.5 to 50 L as a 1% aqueous solution in the case of sodium alginate per 1 kg of the silica sand carrier.

According to the present invention, nitrification and / or denitrification of the wastewater is carried out by treating the nitrogen-containing organic wastewater using the activated sludge-immobilized carrier thus produced. By contacting and treating the activated sludge immobilization carrier with the wastewater, nitrification and / or denitrification according to the present invention can be performed, and various embodiments are possible.

For example, there is a method in which a nitrification reaction is carried out using a nitrifying bacterium in a nitrification section, and the resulting treated water is subjected to a denitrification reaction in a denitrification section using the activated sludge-immobilized carrier. . In the following,
The present invention will be described with reference to a case where sand is used as a carrier.

One embodiment of the present invention is one in which a fluidized bed type denitrification tank and a nitrification tank are arranged in a single reaction tank, and the denitrification tank has a solid-liquid separation effect. In the denitrification tank, using a microorganism-immobilized carrier using sand as the carrier, the concentration of microorganisms is increased to increase the reaction rate, and as an upward flow type fluidized bed, anaerobic reaction conditions are maintained. , Occurs S
It has a function of capturing S and has a solid-liquid separation effect. No clogging of the fluidized bed due to the capture of SS occurs. The nitrification tank uses a carrier to increase the nitrification rate,
The denitrification tank is provided with a solid-liquid separation function and the sedimentation tank is eliminated, so that a compact, single-tank type biological nitrification denitrification treatment system can be provided.

This method can be carried out, for example, by the apparatus shown in FIG. The biological treatment tank 1 is divided into a denitrification tank 3 and a nitrification tank 4 by a partition 2 installed diagonally. In the nitrification tank 4, the immobilized carrier holding the nitrifying bacteria flows by aeration, and the BOD oxidation and nitrification reaction are progressing.
The nitrification-treated water from which the carrier has been separated by the strainer 5 installed at the bottom is circulated to the denitrification tank 3 by the circulation pump 6. The denitrification tank 3 is a fluidized bed using sand as a carrier, and the organic wastewater A containing nitrogen and the circulating liquid from the nitrification section flow in from below, and the fluidized state is maintained. As the denitrification reaction proceeds in the fluidized bed, solids in the wastewater are captured in the fluidized bed, and the clarified treated water B flows into the nitrification tank from above. The treated water C after carrier separation flows out from the upper part of the nitrification tank. The nitrogen-containing organic wastewater A is stored in a raw water tank 8, and the temperature is controlled using a cooler 9 or the like if necessary. Reference numeral 10 is a pump for supplying raw water, such as a bellows pump.

Nitrogen-containing organic wastewater A is oxidized in an aerobic state under aeration conditions by nitrifying bacteria or the like immobilized in a gelling carrier in a nitrification tank 4 to become oxidized nitrogen. The oxidation of BOD also proceeds at the same time. A part of the nitrification liquid from which the carrier has been separated flows into the lower part of the denitrification tank 3 together with the wastewater by the circulation pump 6, and a denitrification reaction occurs in which oxidized nitrogen becomes N ₂ gas using BOD in the wastewater as a reducing agent. The denitrification tank 3 holds a high concentration of microorganisms by artificial granulated sludge using sand as a carrier, and the denitrification reaction proceeds at a high speed. Due to the upward flow of the circulating liquid from the nitrification tank, the floating / fluid state of the fluidized bed is maintained, and an interface between the fluidized bed and the treated water is formed. Since solids are retained in the fluidized bed,
The treated water on the interface becomes clear and is discharged as treated water (effluent) through the next nitrification tank (B → C).

The nitrification tank 4 accommodates nitrifying bacteria. Nitrifying bacteria widely include nitrites that oxidize ammonium ions to nitrite ions and nitrite bacteria that oxidize nitrite ions to nitrate ions. And Nitrosomonas, Nitr
Osococcus spp. and Nitrobacter spp. are exemplified. As the nitrifying bacteria, isolated bacteria may be used, but according to a conventional method in the art, mixed bacteria may be used, or a contained substance may be used, and a commercially available product may also be used. Further, for example, activated sludge contains various nitrifying bacteria. Therefore, activated sludge may be used as the nitrifying bacteria, or a cell mixture separated from the nitrification tank may be used.

The nitrifying bacteria may be used as they are in a nitrification tank, but it is preferable to use them by fixing them to various carriers for the purpose of preventing run-off and densification. Various types of nitrifying bacteria immobilized on a carrier are already commercially available and are freely available. For example, nitrifying bacteria immobilized on a gelling carrier (trade name: Bio-N Cube: manufactured by Hitachi Plant Construction Co., Ltd.) Is one of preferred examples.

In another embodiment of the present invention, the activated sludge-immobilized carrier is accommodated in a biological treatment tank, a nitrification reaction of the wastewater is performed at a lower portion thereof, and a denitrification reaction is performed at an upper portion thereof. A nitrification and denitrification method of the wastewater (hereinafter referred to as a fluidized bed sand carrier nitrification denitrification method or a fluidized bed wherein nitrification and denitrification are carried out simultaneously with nitrification in one biological treatment tank without providing a partition for partitioning both reactions in the inside thereof. Sand carrier method).

In the fluidized bed sand carrier method, the nitrification and denitrification treatments are performed in one biological treatment tank, and in addition to the use of the activated sludge fixed carrier, it also functions as a solid-liquid separation tank. is there. Therefore, this biological treatment tank can be said to be a fluidized bed nitrification denitrification / solid-liquid separation tank.

The activated sludge-immobilized carrier may be produced by the above-described method.
Biofilm particles having a diameter of 0.3 to 0.8 mm self-granulated with silica sand of a diameter as the nucleus. Unlike activated sludge floc, the sedimentation speed is remarkably fast, so the sludge concentration is high (MLVSS 1.5 to 3).
%) Can be maintained.

This method can be carried out, for example, by the apparatus shown in FIG. Reference numeral 1 denotes a biological treatment tank.
The biological treatment tank forms a fluidized bed nitrification denitrification / solid-liquid separation tank as described above. In the present embodiment, two biological treatment tanks 1 are provided in parallel, but only one tank or a number of them may be arranged in parallel. Further, if necessary, the wastewater treatment may be performed at a higher level by being provided in series.

The biological treatment tank 1 preferably has a central portion, but a draft tube 2 is provided at an appropriate position, and air is supplied from an air pipe 3. Organic wastewater A containing nitrogen is
First, the sludge sent to the sedimentation basin 6 and settled out is taken out from the bottom by a pump and transferred to the sludge dewatering step. In addition,
The first sedimentation basin 6 may be a filtration system using a filter medium, in addition to the illustrated sedimentation basin system. On the other hand, inflow raw water (first settling water)
B is mixed with circulating water having a low SS concentration in which oxygen is sufficiently dissolved in the downdraft tube 2, and is then uniformly fed to the bottom by the downflow axial pump 4 and the distributor 5 installed at the lower part.

The activated sludge carrier is accommodated in the biological treatment tank 1, and a fluidized bed is formed together with the raw water. The fluidized bed carrier sludge is supplied with dissolved oxygen (D
O) is used to nitrify NH ₄ —N and adsorb organic substances (BOD, COD, etc.) in raw water. Since the circulating water consumes dissolved oxygen as it rises, the upper fluidized bed sludge performs denitrification by decomposing the adsorbed organic matter using the bound oxygen of oxidized nitrogen. Thus, in the biological treatment tank, the nitrifying bacteria contained in the activated sludge work in the lower aerobic region, and the denitrifying bacteria contained in the activated sludge work in the upper anaerobic region, According to the present invention,
One biological treatment tank, one microorganism source (activated sludge)
Thus, a remarkable effect is achieved in that two processes, nitrification and denitrification, can be performed simultaneously.

The suspended solids (SS) in the raw water adhere to and are adsorbed and removed from the biofilm particles during the ascent of the fluidized bed, so that a biological filtration action works.
Is almost transparent at 10 mg / L or less and solid-liquid separation is completely performed, so that the effluent C can be subjected to coagulation sedimentation as it is. Therefore, according to the present invention, not only the two treatments of nitrification and denitrification can be performed simultaneously in one biological treatment tank, but also the solid-liquid separation can be performed simultaneously. It has a remarkable effect.

The effluent C treated in this way is sent to the coagulation sedimentation tank 7 if necessary, and the coagulant tank 8
, An inorganic coagulant is added thereto to cause coagulation and sedimentation, and the supernatant is taken out as discharge water D and discharged into a river or the like. On the other hand, the settled sludge is taken out as excess sludge from the bottom of the coagulation sedimentation basin 7 and transferred to the sludge dewatering step.

The coagulation sedimentation basin 7 can be sufficiently used by slightly modifying the existing final sedimentation basin, and can remove SS, chromaticity and phosphorus. On the other hand, a method of treating wastewater in an aeration tank that contains and floats activated sludge (standard activated sludge method) has been conventionally performed. However, this standard activated sludge method can hardly remove nitrogen. Since the fluidized bed sand carrier method does not require returned sludge and can maintain a high sludge concentration, the existing aeration tank can be modified to achieve nitrogen removal and solid-liquid separation with the same residence time. In addition, by changing the unnecessary final sedimentation tank to a coagulation sedimentation tank and changing the application,
The secondary treatment facility can be converted to an advanced treatment facility including nitrogen and phosphorus removal without increasing the site area and tank capacity.

[0039]

[Example 1] 50 g of silica sand (0.074 to 0.149 mm)
Then, 80 cc of a 1% aqueous solution of a strong cationic polymer flocculant represented by the following chemical formula 1 was added, and dried at 90 ° C. for 4 hours to evaporate water. Then, this was cooled to room temperature to obtain a cationized carrier.

[0040]

Embedded image

On the other hand, the above treated silica sand was added to 3 L of activated sludge (MLSS 5000 mg / l) collected from a sewage treatment plant, and the mixture was stirred for several minutes at 150 rpm with a jar tester. . To this was added 500 ml of a 0.1% aqueous solution of a medium anionic polymer flocculant shown in Chemical Formula 2 below, mixed and stirred at 150 rpm for several minutes.

[0042]

Embedded image

Further, 300 ml of a 0.1% aqueous solution of the same strong cationic polymer flocculant as above was added and mixed to obtain a particle size of 5%.
A somewhat large aggregate of about mm to 1 cm was formed. When this was further stirred at 150 rpm for about 10 minutes, it could be homogenized to a size of 2 mm or less. To this was added 400 cc of a 1% aqueous solution of sodium alginate, mixed and stirred at 150 rpm for several minutes. When stirring continuously at 150 rpm, 600 cc of a 0.2 M calcium chloride aqueous solution was gradually added thereto, and the sodium alginate permeated and adhered to the aggregate changed into a gel of calcium alginate, and the aggregate was hard. Covered with gel. The whole amount of the aqueous calcium chloride solution was charged, and the mixture was further stirred at 150 rpm for about 30 minutes, so that the size was uniformed to about 2 mm. Almost 100% of the activity remained.

[0044]

Example 2 According to Example 1, a silica sand having a diameter of 0.1 mm was used as a carrier, and a cationic polymer was initially added to silica sand, followed by stirring and evaporation to dryness to coat a polymer. After mixing and stirring, alginic acid, cationic polymer and calcium chloride were sequentially added, and the mixture was stirred with a jar tester to produce artificial biopellets. The average diameter of this sand carrier sludge during manufacture is approximately 0.2 mm
Met.

[0045]

Example 3 A sand carrier was obtained in the same manner as in Example 2 except that casein and sodium hydroxide were used as a paste and a curing agent, and activated sludge was firmly coagulated and adhered to the surface thereof. When the residual activity ratio in this case was measured, it was about 100%.

[0046]

Example 4 The following artificial sewage was treated using the apparatus shown in FIG.

(1) Apparatus used The biological reaction tank is composed of an upward-flowing sand carrier fluidized bed denitrification column and a nitrification column containing nitrifying bacteria-encapsulated pellets. The nitrification liquid is circulated by a circulation pump. I have.
The tank capacity is 15 L for the nitrification tank and 15 L for the denitrification tank, and the dimensions are 1.0 mH × 0.15 mW × 0.3 mL. The partitions of both tanks are arranged obliquely so as to form a sludge interface in an upflow column. The circulation pump is a magnet pump (1-10L /
min), the circulation flow rate was controlled with a rotor meter and a valve. In the nitrification column, stirring of the entrapping immobilization carrier and supply of DO were necessary, so air was constantly supplied from an air pump as air diffused for coarse foam aeration (air volume 2-6 L / min). In order to prevent the entrapping immobilized pellets from being mixed into the circulating liquid, a wedge wire strainer having a mesh width of 1.5 mm is provided below the nitrification column. The water temperature in the reaction tank was maintained at 22 ° C. by a thermostat heater. Raw water is supplied to the lower part of the denitrification column by a bellows pump.
L / Hr (residence time 6 hours) was set, and the residence time was changed by adjusting the operation time of the pump using a timer.

As the sand carrier sludge, the one produced in Example 2 was used, and as the pellet for encapsulating nitrifying bacteria, a commercially available product (trade name: Bio-N Cube: manufactured by Hitachi Plant Construction Co., Ltd.) was used.

(2) Composition of artificial sewage The concentration of artificial sewage was set to 250 mg / L for glucose and 40 mg / L for NH ₄ -N, assuming a general concentration of inflow sewage.
Solutions A, B, C, and D in the BOD test (sewage test method) were added as nutrients and buffers to 1 L of artificial sewage, and 5 mL of Solution A, and 1 mL of B, C, and D, respectively. The amount of artificial sewage used was initially started from 30 L / day (residence time: 24 hours) and increased to 60 L / day (12 hours) and 120 L / day (6 hours). The sewage was cooled to 4 to 6 ° C to prevent spoilage.

(3) Operating conditions The operating conditions are shown in Table 1 below.

[0051]

[Table 1]

(4) Measurement The following items were measured by the respective measurement methods. NH ₄ -N: Distillation titration method Oxidized nitrogen: UV absorbance method Glucose: Phenol sulfate method MLSS: Centrifugal drying method MLVSS: 600 ° C., 1 hour heating method DO and pH: Electrode method Single particle sedimentation rate: 100 cm fluorometer

(5) Operation Results Table 2 below shows the measurement results of the sludge concentration and the sedimentation velocity one month after the start of continuous operation under the above conditions.

[0054]

[Table 2]

As is apparent from the above results, MLVSS
The concentration is higher at the lower part and lower at (30,000 mg / L), but is several steps higher than the activated sludge method (8,70 mg / L).
0 mg / L). Particle size of carrier sludge is 0.2mm at the top
~ 0.4mm, the bigger it goes down (0.6mm ~ 2m
m). S in the circulating liquid passed through this sludge layer
The S concentration was extremely low, about 2 to 10 mg / L.

As is apparent from the above results, when the fluidized bed sludge was subjected to single particle sedimentation using a 100 cm transparence meter glass tube, the sedimentation velocity was 33% for the small particles in the upper part.
cm / min (20 m / Hr), 163 cm / min (9
8m / Hr). The SS concentration in the circulating water was extremely low, about 2 mg / L to 10 mg / L.

FIG. 4 shows a change in the nitrogen load and a change in the nitrogen removing ability from the start of the operation. As is evident from the results, the nitrogen concentration in the treated water decreased as the load increased.However, over time, the nitrifying bacteria in the entrapping immobilization carrier in the nitrification zone and the sand in the denitrification zone It is considered that the propagation of the carrier sludge progressed together.

That is, the load was increased by shortening the residence time without changing the substrate concentration. However, the nitrogen removal rate was improved with the increase in the load, and the nitrogen concentration in the treated water at the time of residence for 6 hours was NH ₄ − N2-5 mg / L and NOx-N2-5 mg / L, and the removal rate showed a high value of 75-90%. The reason for this is the acclimation of the entrapping immobilized nitrifying bacteria and the increase in the amount of sand carrier sludge.
Since the operation was performed without removing the sludge, the amount of the sand carrier sludge continued to increase, and when the circulation flow rate was low, the smell of hydrogen sulfide was observed. At this time, the reason why NH ₄ —N also shows a higher value seems to be elution due to anaerobic decomposition. If the sludge concentration becomes too high, the fluidization is not performed as a whole, and a short circuit phenomenon and anaerobic phenomenon occur, so that the treatment performance seems to be reduced.

[0059]

Example 5 Sewage was treated by the fluidized bed sand carrier method using the apparatus shown in FIG. As a control, sewage was treated by a standard activated sludge method.

As a result, the residence time = 6 hours and the MLVSS
The value was 2000 mg / L in the case of the standard activated sludge method, while it was 15,000 mg / L in the case of the fluidized bed sand carrier method. Also, regarding the water quality of the effluent, a remarkable difference was observed between the two, as shown in Table 3 below, confirming the remarkable effect of the present method.

[0061]

[Table 3]

[0062]

In the sewage treatment, the artificially granulated sand carrier grew smoothly without breakage, and circulating water containing almost no SS was obtained. In addition, by combining with the immobilized nitrifying bacteria treatment, it became possible to perform nitrification denitrification with the residence time of the standard activated sludge method. Furthermore, according to the present method, the sedimentation speed of the sand carrier sludge is remarkably fast, so that nitrification denitrification and solid-liquid separation can be performed simultaneously. In addition to the rapid nitrification and denitrification in a small-capacity tank, chromaticity and phosphorus can be removed, and the sludge concentration can be maintained at a high level, so that there is no need to return the sludge.

[Brief description of the drawings]

FIG. 1 shows a flow sheet of a circulation type nitrification and denitrification method.

FIG. 2 shows an apparatus for performing a nitrification denitrification method according to the present invention.

FIG. 3 shows an apparatus for carrying out the nitrification denitrification method (fluidized bed sand carrier nitrification denitrification method) according to the present invention.

FIG. 4 shows the daily change of nitrogen load and nitrogen concentration of treated water.

Claims (5)

[Claims] An activated sludge is adhered to a carrier, and then the treated sludge is treated with a paste, and then the nitrogen-containing organic wastewater is treated using an activated sludge-immobilized carrier obtained by curing. A method for nitrifying and denitrifying the wastewater. 2. A nitrification reaction is performed in a nitrification section using a nitrifying bacterium, and the resulting treated water is subjected to a denitrification reaction in a denitrification section using the activated sludge-immobilized carrier. The method of claim 1. 3. The activated sludge immobilization carrier is accommodated in a biological treatment tank, a nitrification reaction of the wastewater is performed at a lower portion thereof, and a denitrification reaction is performed at an upper portion thereof, and the two reactions are defined inside. The method according to claim 1, wherein denitrification is performed simultaneously with nitrification in one biological treatment tank without providing a partition wall. 4. A short-time and small-scale apparatus characterized in that nitrogen-containing organic wastewater is subjected to nitrification denitrification and solid-liquid separation by the method according to any one of claims 1 to 3. A method for treating the wastewater using the same. 5. The method according to claim 1, wherein the carrier comprises sand, quartz sand, shell fossil, cristobalite, clay mineral, iron powder, and / or porous glass. The method described in.