JPH081193A - Method and apparatus for treating organic waste water - Google Patents

Abstract

PURPOSE:To provide an org. waste water treatment method and apparatus using a polymeric gel carrier having bacteria inclusively fixed thereon to obtain a high nitrogen removing rate without adding a carbon source such as methanol, enabling high load operation and requiring no large capacity treatment tank. CONSTITUTION:A polymeric gel carrier of which the specific gravity is higher than that of water having activated sludge inclusively fixed thereon is held to a nitrification part 4 and a denitrification part 5 and org. waste water is supplied to the upper part of the denitrification part 5 to be allowed to flow through the denitrification part 5 as a descending stream. Since a large amt. of floating org. matter is caught by the bed of the polymeric gel carrier by the descending stream of the denitrification part 5, growing environment actively propagating acid producing bacteria solubilizing the floating org. matter is formed and the caught floating org. matter is made soluble to become a definite low level without being increased in its amt. and pressure loss is kept low and the clogging of the denitrification part 5 is prevented. Since the org. acid formed by solubilization is utilized in denitrification reaction, the nitrogen removing rate of treated water is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for treating organic wastewater such as sewage, housing effluent, agricultural settlement effluent, other domestic effluent, leachate effluent, factory effluent, and more particularly, a polymer. The present invention relates to a method and an apparatus for biologically efficiently removing nitrogen components contained in organic wastewater by entrapping and fixing microorganisms.

[0002]

2. Description of the Related Art A biological nitrogen treatment method using suspended activated sludge is known as an economical and practical method for removing organic nitrogen and ammonia nitrogen in organic wastewater. This treatment method, a denitrification tank kept anaerobic is provided in the preceding stage of the nitrification tank kept aerobic, between the nitrification tank and the denitrification tank, water to be treated is circulated through floating activated sludge, In the nitrification tank, organic nitrogen and ammonia nitrogen in the organic wastewater are oxidized to nitrite nitrogen or nitrate nitrogen by the action of nitrifying bacteria in the activated sludge under aerobic conditions, and in the denitrification tank, While the organic wastewater to be treated flows in, the organic matter of the inflowing organic wastewater is used as an organic carbon source (hydrogen donor) necessary for the denitrification reaction,
The nitrite nitrogen or nitrate nitrogen generated in the nitrification tank is reduced to nitrogen gas by the action of denitrifying bacteria in activated sludge under anaerobic conditions, and the nitrogen gas is removed as a gas from the water system to remove nitrogen. Is to do.

As a concrete apparatus for the biological nitrogen treatment method using this suspended activated sludge, for example, Japanese Patent Publication No.
There is known a one-tank type apparatus described in Japanese Patent Publication No. 60918 and Japanese Patent Publication No. 63-65397, which saves a lot of site area. That is, these devices consist of a single tank integrally formed with the denitrification section (denitrification tank) located below and the nitrification section (nitrification tank) located above, and the inside of the tank is directed downward. It is a thing. In particular, Japanese Examined Japanese Patent Publication 57-6091
The apparatus disclosed in Japanese Patent No. 8 has a dissolved oxygen consumption section between the nitrification section and the denitrification section for preventing a large amount of nitrification liquid from flowing down to the denitrification section. In addition, Japanese Examined Japanese Patent Publication 63-6539
In the apparatus of No. 7, a partition wall for partitioning the nitrification section and the denitrification section is provided in the tank, and a narrow communication path communicating from the nitrification section to the denitrification section is formed in the partition wall, and the partition section is further provided. An air lift pipe is provided on the wall, which is inserted into both the nitrification section and the denitrification section and is provided with an oxygen-containing gas inlet tube communicating from the denitrification section to the nitrification section.

However, these floating activated sludge treatment devices have a limitation in high-load operation, and although the space of the site is reduced, the tank itself requires a large capacity, and the treatment device is In addition to the disadvantage that it becomes large, in order to maintain a high nitrogen removal rate in the treated water, a new carbon source such as methanol is required as an organic carbon source (hydrogen donor) necessary for the denitrification reaction. there were.

As a solution to this problem to some extent, a high concentration of activated sludge in the tank is maintained by utilizing a large amount of activated sludge adhering to the surface of a filler having a specific gravity smaller than that of water described in JP-B-63-19239. There are biological nitrogen treatment devices that operate at high load. That is, in this processing apparatus, as shown in FIG. 13, a packing layer 53 formed of a packing material having a specific gravity smaller than that of water is provided below a floating prevention member 52 such as a perforated plate or a net provided above the processing tank 51. And a diffusing means 54 such as a diffusing pipe for ejecting air bubbles is provided in the middle part of the packed bed 53, and the packed bed above the diffusing means 54 is the nitrification section A, The packed bed below the means 54 is used as the denitrification section B, the raw water inflow pipe 55 is inserted in the upper part of the denitrification section B, and water is sent from the lower part of the denitrification section B to the nitrification section A for desorption. The denitrifying liquid water supply means 56 for making the flowing water passing through the nitrification section B downward flow is provided. The numeral 57 in the figure is a treated water outflow pipe.

In the apparatus disclosed in Japanese Patent Publication No. 63-19239, the SS (suspended material) trapped in the packed beds A and B flows downward from the inside of the bed, and even if the backwashing operation is not performed, the SS is suspended. Has the advantage that it does not accumulate in the packed beds A and B. However, a large amount of activated sludge that adheres to the surface of the packing material is easily peeled off and is discharged to the outside of the treatment system. Although the activated sludge concentration in the tank can be maintained higher than that of conventional floating activated sludge, The activated sludge concentration cannot be maintained for high-load operation, the quality of the treated water such as nitrogen removal rate is not stable, and as a result, the treatment tank must have a large capacity. In order to maintain a high nitrogen removal rate, the problem that a new carbon source such as methanol as well as raw water is necessary as an organic carbon source (hydrogen donor) necessary for the denitrification reaction has not been solved.

A device disclosed in Japanese Examined Patent Publication No. 1-37988 is known as a device capable of more stable high load operation than the above device. In this device, the lower part of a single tank is an anaerobic denitrifying part filled with a denitrifying bacterium immobilizing carrier in which only cultured denitrifying bacterium is immobilized inside the polymer (so-called entrapped), and the upper part is cultivated nitrifying bacterium. In order to prevent a mixture of the denitrifying bacteria-immobilized carrier and the nitrifying bacteria-immobilized carrier, the aerobic nitrification part is filled with the nitrifying bacteria-immobilized carrier in which only the polymer is fixed (encapsulated). A mesh screen for partitioning the denitrification section and the nitrification section is provided in the middle of the tank body, and a nitrification solution water supply means is provided which is a pump pipe for extracting the nitrification solution from the upper part of the nitrification section and supplying it to the lower part of the denitrification section. Oxygen is consumed while the nitrification solution moves through the nitrification solution water supply means and hits the denitrification section. In the denitrification section, the circulating water is made an upward flow, that is, the circulating water in the tank is dewatered as described above. By circulating the upward flow from the nitriding section to the nitrification section, While easier to maintain the sex, a biological nitrogen treatment apparatus as small as possible the pressure loss of the packed bed of immobilized carrier.

The apparatus disclosed in this Japanese Patent Publication No. 1-37988 is different from that of the above-mentioned Japanese Patent Publication No. 63-19239 in that it uses microorganisms which are easily peeled off and adhered to the surface of the filling material. Since the microorganisms immobilized inside the molecule-immobilized carrier are also used, there is an advantage that the concentration of activated sludge in the tank can be more stably maintained at a high level and a high load operation can be performed. However, this device, like the conventional device, requires a new carbon source such as methanol in addition to raw water as an organic carbon source necessary for the denitrification reaction in order to maintain a high nitrogen removal rate of the treated water. It was

An apparatus capable of entrapping and fixing a specific microorganism and performing a high load operation, which solves the problem of requiring a new carbon source such as methanol, is disclosed in Japanese Patent Publication No. 2-7716.
There is a device described in the publication. This device fills the bottom of the tank with an acid-producing bacterium-immobilized carrier in which only the cultured acid-producing bacteria are immobilized inside the polymer, and fixes only the denitrifying bacteria cultured in the top of the tank inside the polymer. The denitrification tank filled with the immobilized denitrifying bacteria immobilizing carrier and the nitrification tank in which the nitrifying bacteria immobilizing carrier in which only the cultured nitrifying bacteria are immobilized inside the polymer are made to flow sequentially are disposed from the bottom of the denitrifying tank. With
Nitrification liquid water supply means for supplying water from the upper part of the nitrification tank to the lower part of the denitrification tank is provided so that the flow water passing through the denitrification tank becomes an upward flow so that the pressure loss of the packed bed of the immobilization carrier is minimized. In the apparatus described in Japanese Patent Publication No. 2-7716, the denitrification reaction is carried out by solubilizing floating organic substances in wastewater with an acid-producing bacterium growing in a denitrification tank and an acid-producing bacterium-immobilized carrier to decompose it into an organic acid. The deficiency of the organic carbon source as a hydrogen donor required for the above is compensated.

[0010]

However, when the denitrification tank is filled only with the denitrifying bacterium-immobilized carrier as in the apparatus described in Japanese Patent Publication No. 2-7716, the Japanese Patent Publication No. 1-37988 is naturally used. The same as the device described in the publication, the nitrogen removal rate of the treated water is low, and the one in which the acid-producing bacteria-immobilized carrier is additionally filled in the lower part of the denitrification tank can obtain a certain nitrogen removal rate, but the denitrification tank itself There is a problem in that a large capacity is required, and since the acid-producing bacteria are immobilized in addition to the nitrifying bacteria and the denitrifying bacteria, the production cost of the immobilization carrier is high.

As a result of careful examination of this, in order to make it easier to maintain the anaerobic property of the denitrification section and to minimize the pressure loss of the packed bed of the immobilization carrier, the flowing water of the denitrification section is allowed to flow upward. Then, it was found that the amount of floating organic matter trapped between the entrapping immobilization pellets in the denitrification tank was small and efficient solubilization by the acid-producing bacteria was not possible. Furthermore, when a gel-type polymer gel carrier is used as a carrier for immobilizing microorganisms, simply encapsulating and acclimatizing the activated sludge and acclimatizing (acclimating) the nitrifying bacteria and the denitrifying bacteria depending on the aerobic or anaerobic environment. It has been found that nitrifying bacteria become a priority species and it is not necessary to pre-cultivate a specific microorganism and entrap it in a carrier.

The present invention has been made in view of the above,
Using a polymer gel carrier that entraps and fixes microorganisms inside,
A high nitrogen removal rate can be obtained without adding a new carbon source such as methanol, and further, it is possible to provide a method and an apparatus for treating organic wastewater that can operate under high load and does not require a large capacity tank itself. With the goal.

[0013]

The method for treating organic wastewater according to claim 1 of the present invention which achieves the above object, is biologically organic by circulating water between the nitrification section and the denitrification section. In a treatment method of organic wastewater for removing nitrogen in wastewater, a polymer gel carrier having a larger specific gravity than water with activated sludge fixed inside is retained in an aerobic nitrification section and an anaerobic denitrification section, respectively. At the same time, the organic wastewater is supplied to the upper part of the denitrification section, and the flow water passing through the denitrification section is made downward flow.

Further, the method for treating organic wastewater according to claim 2 of the present invention is an organic wastewater that biologically removes nitrogen from the organic wastewater by circulating water between the nitrification section and the denitrification section. In the wastewater treatment method, a polymer gel with a higher specific gravity than water with nitrifying bacteria fixed inside is held in the aerobic nitrification part, and a polymer gel with a higher specific gravity than water with denitrifying bacteria fixed inside. The carrier is held in the anaerobic denitrification section, the organic wastewater is supplied to the upper part of the denitrification section, and the flow water passing through the denitrification section is made downward flow.

The method for treating organic wastewater according to claim 3 of the present invention is the method for treating organic wastewater according to claim 1 or 2, wherein the redox potential of the lower part of the denitrification section is from -200 mV. It is characterized by being maintained in the range of -400 mV.

According to a fourth aspect of the present invention, in the organic wastewater treatment apparatus, an anaerobic denitrification unit holding a polymer gel carrier having a specific gravity larger than that of water in which activated sludge is fixed, and the polymer gel. An aerobic nitrification section holding a carrier, and a wastewater supply port for supplying organic wastewater provided in the upper part of the denitrification section,
The nitrification solution water supply means for supplying water from the nitrification section to the upper part of the denitrification section, and the denitrification solution water supply means for supplying water from the lower part of the denitrification section to the nitrification section are provided, and the flowing water passing through the denitrification section flows downward. The feature is that

The organic wastewater treatment apparatus according to a fifth aspect of the present invention is an anaerobic denitrification unit which holds a polymer gel carrier having a specific gravity larger than that of water in which denitrification bacteria are fixed, and a nitrifying bacterium. A polymer gel carrier having a specific gravity greater than that of water fixed inside, and an aerobic nitrification unit holding the polymer gel carrier, and a waste water supply port provided at the upper part of the denitrification unit for supplying organic waste water And a denitrification solution water supply means for supplying water from the nitrification section to the upper part of the denitrification section and a denitrification solution water supply means for supplying water from the lower part of the denitrification section to the nitrification section, to lower the flow water passing through the denitrification section. It is characterized by a countercurrent.

Further, in the organic wastewater treatment apparatus according to claim 6 of the present invention, a polymer having a specific gravity larger than that of water in which an aeration means is provided in the treatment tank and activated sludge is fixed in the treatment tank. Introducing a gel carrier into a denitrification section below the air diffusing means filled with the polymer gel carrier, and above the air diffusing means into a nitrification section for flowing the polymer gel carrier, A denitrification liquid water supply means for providing a wastewater supply port for supplying organic wastewater to the upper part of the nitrification section, and for supplying water from the lower part of the denitrification section to the nitrification section to make the circulating water passing through the denitrification section a downward flow Is provided.

Further, in the organic wastewater treatment apparatus according to claim 7 of the present invention, the specific gravity is larger than that of water in which a degassing means is provided in the processing tank and denitrifying bacteria are fixed in the lower part of the aeration means. A denitrification section filled with a polymer gel carrier, and a nitrification section for flowing a polymer gel carrier having a greater specific gravity than water having nitrifying bacteria fixed therein above the diffusion means, and the denitrification section A wastewater supply port for supplying organic wastewater was provided in the upper part, and a denitrification liquid water supply means for supplying water from the lower part of the denitrification section to the nitrification section to make the flowing water through the denitrification section a downward flow was provided. It is characterized by

The organic wastewater treatment apparatus according to claim 8 of the present invention is the organic wastewater treatment apparatus according to any one of claims 4 to 7, wherein the denitrification section is provided below the denitrification section. An air diffuser for backwashing the polymer gel carrier-filled layer in the denitrification section is provided.

Further, the organic wastewater treatment apparatus according to claim 9 of the present invention is the organic wastewater treatment apparatus according to any one of claims 4 to 8, wherein the polymer of the denitrification section is a polymer. The polymer gel carrier support formed with a gap larger than the diameter of the gel carrier is provided in the denitrification section in one or more steps.

In the present specification, the nitrification section and the denitrification section mean not only a part of a single tank, but also the nitrification section and the denitrification section themselves are composed of different tanks. Is also included and shall be understood in a broad sense.

The activated sludge is mainly composed of bacteria having a metabolic function of ingesting organic substances and inorganic substances in wastewater as nutrient sources, and is composed of dozens or more kinds of microorganisms such as fungi, protozoa, and micro metazoa, nitrosomonas, Nitrifying bacteria such as Nitrobacta and denitrifying bacteria that are facultative anaerobic bacteria such as Pseudomonas and Alcaligenes are always present.

The polymer gel carrier for fixing activated sludge, nitrifying bacteria or denitrifying bacteria is polyvinyl alcohol (P
VA), polyethylene glycol (PEG), acrylamide monomer (ACAM), and the like, each of which is a gelled polymer having a high water content and a micropore size of about 10 μm to 0.1 μm. Possesses good permeability to dissolved organic substances such as BOD substances, organic nitrogen, ammonia nitrogen, and oxygen, and has a certain level of physical strength (compressive strength 1 to 4 kg / cm) that can be used for wastewater treatment.
² )), which is suitable for the growth environment of microorganisms.

As a method for fixing activated sludge, nitrifying bacteria or denitrifying bacteria, in ACAM and PEG, the microorganisms to be fixed are mixed with a polymer solution of ACAM and PEG to form a crosslinking agent (N,
Various methods are known, such as N'-methylenebisacrylamide) and a polymerization agent (potassium persulfate) and polymerization at room temperature. When using PVA, PV
After freezing the mixed solution of A and the microorganisms to be immobilized at -5 ° C or lower,
It is entrapped and immobilized by a method such as PVA-freezing method in which thawing and drying are performed to form a gel. Immobilized carriers on which activated sludge, nitrifying bacteria or denitrifying bacteria are fixed by these methods are
It has a specific gravity of about 1.03 to 1.07, which is somewhat heavier than water, and is almost the same as that of the polymer gel carrier in which microorganisms are not immobilized.

When the polymer gel carrier is held in the aerobic nitrification section and the anaerobic denitrification section, it is necessary to strictly separate the nitrification section polymer gel carrier and the denitrification section polymer gel carrier. However, the polymer gel carrier in the vicinity of the boundary between the nitrification section and the denitrification section may be mixed at about 5-10% for 1 to 4 hours. Therefore, "hold" in this specification
The meaning of is to be understood in its broadest sense, including not only strictly maintaining it in that environment, but also generally maintaining it in an environment to the extent that its purpose can be achieved.

In the present invention, the water flowing through the denitrification section is made to flow downward, but the flow velocity of this denitrification section is affected by the position of the treated water outlet. That is, if the treated water outlet is provided in the denitrification section, the downward flow velocity of the denitrification section becomes faster,
Further, if the treated water outlet is provided in the nitrification section, the downward flow velocity of the denitrification section becomes slow. However, in the biological denitrification treatment method, the amount of water circulating in the nitrification section and the denitrification section is several times larger than the amount of supplied wastewater, so the downward flow velocity does not significantly affect, and in the present invention, denitrification is performed. Since it is only necessary that the circulating water passing through the section has a downward flow, the position of the treated water outlet is not particularly limited and may be the nitrification section or the denitrification section.

The nitrification solution water supply means for supplying water from the nitrification section to the upper part of the denitrification section in the apparatus according to claims 4 and 5 of the present invention includes pipes provided with a pump, air lift and gravity (moved by gravity). ) Examples include simple piping. Further, in the tank in which the nitrification section and the denitrification section are integrally formed in the upper and lower parts, the tank wall itself near the boundary between the nitrification section and the denitrification section functions as the nitrification solution water supply means. The nitrification solution extraction position in the nitrification section is an aeration means for maintaining aerobic property even if the nitrification section is fixed by a net or the like in which polymer gel carrier groups are provided above and below to form a packed layer. Since at least the nitrification liquid itself is flowing in the nitrification section, it may be at any position in the nitrification section. For example, if a treated water outlet is provided in the nitrification section, a part of the treated water is taken out from the treated water flow path from the treated water outlet, and a pump is installed to feed the treated water as nitrification liquid to the upper part of the denitrification section. The above-mentioned pipe may be used as the nitrification liquid water supply means.

As the denitrification liquid water supply means for supplying water from the lower part of the denitrification section to the nitrification section in the apparatus of claims 4, 5, 6, and 7 of the present invention, a pipe provided with a pump provided on the outer wall of the treatment tank or Examples thereof include a draft tube that forms an air lift, and a draft tube that forms an air lift provided in the processing tank. The denitrifying liquid intake position in the nitrification section is maintained aerobic even if the nitrification section is fixed by a net or the like in which polymer gel carrier groups are provided above and below to form a packed bed, as described above. Since at least the nitrification liquid itself is flowing in the nitrification section by the air diffusing means or the like, it may be located anywhere in the nitrification section. For example, a pipe or a draft tube as a denitrification solution water supply means may be opened above the nitrification section to drop the denitrification solution onto the upper part of the nitrification section.

[0030]

When a polymer gel carrier having activated sludge fixed therein is used as in claims 1, 4 and 6 of the present invention,
First, perform acclimatization (also called acclimatization). This acclimatization operation may be the same as the acclimatization method for general activated sludge treatment. For example, the operation of inflowing the organic wastewater at about 30% of the planned water quantity may be carried out in the same manner as the actual operation condition to plan the wastewater quantity stepwise. There are methods such as approaching the amount of water, and making the amount of wastewater the same as the planned amount of water from the beginning and performing it in exactly the same state as in actual operation.

When the acclimatization operation is performed for 2 weeks to 1 month in this way, the quality of the treated water becomes stable and the actual operation can be performed. That is, in the nitrification part during the acclimatization period, depending on the aerobic environment, nitrifying bacteria become the preferential species inside the polymer gel carrier and change into activated sludge in which organic matter-oxidizing bacteria are mixed, and the polymer gel carrier Nitrifying bacteria and organic matter-oxidizing bacteria also adhere to the outer surface. On the other hand, in the denitrification section, depending on the anaerobic environment, denitrifying bacteria become a priority species inside the polymer gel carrier, and the activated sludge mainly composed of denitrifying bacteria is converted to the outer surface of the polymer gel carrier. Denitrifying bacteria adhere. Further, in the denitrification section, since the organic wastewater is supplied to the upper part of the denitrification section and the flow water flowing through the denitrification section has a downward flow, the specific gravity forming the layer in the denitrification section A large amount of suspended solids in organic wastewater is trapped between the polymer gel carriers, which are large in size, and the organic substances in the suspended solids (hereinafter referred to as floating organic substances) and the anaerobic environment make the polymer gel carrier internal and external. A large amount of acid-producing bacteria, mainly anaerobic bacteria, and absolutely anaerobic bacteria also exist in the denitrification section.

In such a situation, the organic wastewater is supplied to the upper part of the denitrification section, and the floating organic substances in the wastewater continue to be trapped in a large amount in the layer of the polymer gel carrier having a large specific gravity. Acid-producing bacteria that live in large numbers in the area solubilize the floating organic matter to produce organic acids. Therefore, since the trapped floating organic matter is solubilized by the acid-producing bacterium, the amount of the trapped floating organic matter is maintained at a constant low level, and the denitrification part is not blocked,
The pressure loss is kept low. Then, the denitrifying bacterium, which has become a priority species inside and outside the polymer gel carrier of the denitrifying section, needs the organic acid generated by the acid-producing bacterium together with the soluble organic matter of the inflowing wastewater for the denitrification reaction. It is used as a simple organic carbon source (hydrogen donor) to reduce nitrite nitrogen or nitrate nitrogen generated and circulated in the nitrification section to nitrogen gas. Further, the absolutely anaerobic bacterium existing in the denitrification section converts a part of the organic nitrogen in the wastewater into ammonia nitrogen.

The ammonia nitrogen and the remaining organic nitrogen are circulated from the lower part of the denitrification section to the nitrification section along with the circulating water flowing down the denitrification section. In the nitrification section, organic nitrogen is converted into ammoniacal nitrogen by organic matter-oxidizing bacteria, and together with the ammoniacal nitrogen from the denitrification section,
Due to nitrifying bacteria that became a priority species inside and outside the polymer gel carrier,
It is oxidized to nitrite nitrogen or nitrate nitrogen under aerobic conditions. The nitrogen gas generated in the denitrification section exits the water system as a gas while the treated water is circulating in the denitrification section and the nitrification section. In this way, the nitrogen removal process is performed.

When a polymer gel carrier having denitrifying bacteria fixed therein and a polymer gel carrier having nitrifying bacteria fixed therein are used as in claims 2, 5 and 7 of the present invention, the acclimatization period is slightly shorter. However, other than that, there is no difference from the case of using the polymer gel carrier having the activated sludge fixed therein.

That is, even if a polymer gel carrier in which purely cultured nitrifying bacteria and denitrifying bacteria are entrapped and fixed therein is used, only the purely cultured nitrifying bacteria and denitrifying bacteria are always metabolically grown and fixed. Not necessarily. There are various substrate components in the inflowing wastewater, and various microorganisms that contribute to the substrate components inevitably enter from outside the system such as the wastewater or the atmosphere, depending on the substrate components. As a result, during the treatment operation, various microorganisms that contribute to the substrate components of the wastewater to be treated are gradually mixed from the outside depending on the environment of the nitrification part and the denitrification part, and nitrifying bacteria and denitrifying bacteria are formed on the surface and inside the polymer gel carrier. It will be in a state of coexisting with. Therefore, after a while from the start of operation, the state is substantially the same as the case where the polymer gel carrier having activated sludge fixed therein is used.

Moreover, the polymer gel carrier in the vicinity of the boundary between the nitrification section and the denitrification section in the one-tank system is not limited to nitrifying bacteria, but the denitrification bacteria are polymer in the denitrification section. Not only denitrifying bacteria but also nitrifying bacteria are mixed in the gel carrier according to the environment, and the polymer gel carrier in the nitrification part has a denitrifying effect not only in nitrification but also in the polymer gel carrier in the denitrification part. Not only denitrification, but also nitrification is recognized. Therefore,
The polymer gel carrier near the boundary between the nitrification section and the denitrification section has
There is no problem in processing efficiency even if about 5 to 10% is mixed for 4 hours. Therefore, in the present invention, a mesh screen for partitioning the nitrification section and the denitrification section is not particularly necessary.

From the above viewpoints, the nitrifying bacteria and denitrifying bacteria used in claims 2, 5, and 7 do not necessarily need to be pure cultures, and cultures containing nitrifying bacteria and denitrifying bacteria can be used. It can be widely used as long as it contains the culture. Therefore, the activated sludge containing nitrifying bacteria and the activated sludge containing denitrifying bacteria can be used as the nitrifying bacteria and the denitrifying bacteria in claims 2, 5 and 7, respectively, and in this case, it is substantially the same as claims 1, 4, and 6. Will be the same.

As described above, the action in which a microorganism suitable for the environment is mixed and retained inside the polymer carrier by acclimatization, actual operation, etc. is caused by using the gel polymer carrier. .

As in claim 3 of the present invention, the redox potential of the lower part of the denitrification part is in the range of -200 mV to -400 mV, preferably in the range of -200 mV to -300 mV, more preferably in the range of -250 mV to -300 mV. When maintained at, the solubilizing action of the acid-producing bacteria of the floating organic substances that are trapped in a large amount in the layer of the polymer gel carrier due to the downward flow in the denitrification part becomes active, and the denitrification part of the conventional floating activated sludge is activated. In comparison with the case where the target value of maintenance is set in the range of −100 mV to −150 mV, the amount of the floating organic matter trapped becomes a remarkably low level and is maintained at a lower pressure loss. The denitrification part is prevented from being blocked, and the solubilized organic acid is utilized in the denitrification reaction, and the nitrogen removal rate of the treated water is improved.

As a means for maintaining the redox potential of the lower part of the denitrification section within the predetermined range, as described in claim 8 of the present invention, the lower part of the denitrification section is filled with the polymer gel carrier of the denitrification section. It is preferable to employ a method in which an air diffuser for backwashing the layer is provided and the redox potential is maintained within a predetermined range by adjusting the backwash cycle or the backwash time. For example, when the redox potential in the lower part of the denitrification part is high (approaching to the + side), the backwash cycle is lengthened or the backwash time is shortened. When the redox potential is low, the backwash cycle may be shortened or the backwash time may be lengthened. This method of adjusting the backwash cycle or the backwash time can adjust the oxidation-reduction potential of the denitrification section in a short time, so that it does not affect other operating conditions, can be performed easily, and is extremely easy to manage. is there. Further, by providing the backwash air diffuser, it is possible to treat the organic wastewater containing a large amount of floating organic matter, which is convenient.

The gas ejected from the backwash air diffuser may be either an oxygen-rich gas such as air or pure oxygen or an inert gas such as nitrogen gas. In the case of an inert gas, the nitrification solution is simply generated by turbulent flow. Since only the inflow is promoted and the redox potential is raised, the effect is not obtained in the case of the multi-tank system, and an inert gas storage facility or the like is required. In such a case, it is preferable to use oxygen-rich gas as a method of directly supplying oxygen to the anaerobic denitrification section. The redox potential of the lower part of the denitrification part is measured using a platinum-silver / silver chloride inner electrode type composite electrode, and the effluent from the lower part of the denitrification part or the denitrification part passes through the detection end. It may be provided in the flow channel. It is also possible to sample the denitrification liquid from the flow path through which the effluent from the denitrification unit passes or directly from the denitrification unit to measure the redox potential.

As a method for adjusting the redox potential in the lower part of the denitrification section, various methods other than the above-mentioned backwashing time can be adopted. For example, when the redox potential in the lower part of the denitrification part is high, the amount of water passing from the nitrification part to the denitrification part is reduced, or the oxygen supply amount (aeration amount of oxygen-containing gas) in the nitrification part is reduced. By doing so, the redox potential can be lowered. On the other hand, when the redox potential in the lower part of the denitrification section is low, the amount of water passing from the nitrification section to the denitrification section may be increased,
The redox potential can be raised by increasing the oxygen supply amount (aeration amount of the oxygen-containing gas) in the nitrification section.

When the organic wastewater is treated on a large scale or when the height of the denitrification section is increased to save the site area as much as possible, the layer height of the polymer gel carrier-packed layer in the denitrification section is There is a possibility that the polymer gel carrier becomes high and the lower polymer gel carrier is pressed by its own weight to cause consolidation. In that case, as in claim 9 of the present invention, it is preferable to provide the polymer gel carrier support formed with a gap larger than the diameter of the polymer gel carrier in the denitrification section in one or more steps. . When a plurality of stages are provided, the distance between the supports is 1 m or less, preferably 80 cm or less, and more preferably 50 cm or less, whereby the polymer gel carrier can be prevented from being consolidated and the pressure loss can be effectively reduced. . This polymer gel carrier support is filled with the polymer gel carrier in a space below the support while the polymer gel carrier passes through the gap in a stationary state such as when filling the tank with the polymer gel carrier. It is preferable that when a downward flow is generated during operation or the like, as many gaps as possible are formed so that a bridge can be formed on the gap. Although the size of such a gap cannot be generally stated, for example, a slit-like long thin gap having a width of 5 to 10 times the maximum size of the polymer gel carrier is preferable. This polymer gel carrier support may be formed by cutting a plurality of slits in a flat steel plate or by arranging bar-shaped strips in parallel with a gap. With such a polymer gel carrier support, it is possible to reliably prevent compaction of the polymer gel carrier filled in the denitrification section and blockage due to suspended substances trapped between the carriers to keep the pressure loss low. .

[0044]

EXAMPLES An example of applying the present invention to the treatment of sewage as organic wastewater will be described below. In the cylindrical processing tank 1 shown in FIG. 1, a nitrification part 4 having a draft tube 2 in the center of the upper part and an air diffuser 3 (air diffuser) in the vicinity of the lower part is formed, and below the air diffuser 3. Further, the denitrification part 5 is formed by filling a polymer gel carrier having a specific gravity larger than that of water in which activated sludge is fixed to a position separated from the air diffusing pipe 3 by a predetermined distance.

An air supply pipe 30 for supplying air from a blower 20 is connected to the air diffusing pipe 3 of the nitrification unit 4 through the side wall of the processing tank 1. The nitrification section 4 is also filled with a polymer gel carrier having a specific gravity larger than that of water in which activated sludge is fixed, as described later, but the polymer gel carrier is in a state of flowing by the air aerated from the air diffusing tube 3. Become. Therefore, on a part of the side surface of the upper part of the nitrification section 4, a polymer gel carrier separation for separating the flowing polymer gel carrier and preventing it from flowing out of the treatment tank 1 and taking out only the treated water. A section 6 is provided. Polymer gel carrier separation unit 6 in this embodiment
As shown in FIG. 2, a deaeration zone 7 is provided in the interior to further enhance the separation effect between the treated water and the polymer gel carrier to ensure that the polymer gel carrier flows out of the system. Therefore, only the treated water is taken out from the treated water outlet 27.

At the boundary between the nitrification section 4 and the denitrification section 5, there is provided a baffle 26 having a triangular vertical cross section in which the central portion is narrowed toward the upper and lower ends and protrudes inward from the side wall of the processing tank 1. The diameter of the processing tank 1 at that position is narrower than the diameter of the draft tube 2. As shown in FIG. 3, the baffle 26 may have a horizontal central opening of a circular shape (FIG. 3a) or a polyhedral shape (FIG. 3b), and the angle α between the upper end of the baffle and the inner wall of the processing tank 1 30-60 degrees, preferably 3
It is preferable that the angle β between the lower end of the baffle and the inner wall of the processing tank 1 is 0 to 45 degrees, 30 to 60 degrees, and preferably 45 to 60 degrees. Thereby, the fluidity of the polymer gel carrier in the nitrification section 4 is improved, and the polymer gel carrier separation section 6 provided on the upper side surface of the nitrification section 4 is backwashed with air in the denitrification section 5 described later. It is possible to prevent the polymer gel carrier from flowing out of the system without a large amount of bubbles flowing in.

An annular waste water dispersion pipe 28 having a plurality of waste water supply ports facing downward is attached to an upper position of the denitrification section 5 below the air diffusion pipe 3 in the polymer gel carrier packed layer.
A waste water supply pipe 19 from a waste water pit 17 in which a waste water supply pump 18 is interposed is connected to the waste water dispersion pipe 28.

A support plate 13 (polymer gel carrier support) for dispersing and supporting the polymer gel carrier group in the denitrification part is provided in the middle of the denitrification part 5 while being supported by the side wall of the processing tank 1. ing. This support plate 13 prevents the polymer gel carrier underneath from being pressed by the self-weight of the polymer gel carrier to cause consolidation, and the suspended matter and excess sludge in the tank are accumulated between the polymer gel carrier groups. This is to prevent the loss from increasing. A slit (gap) is cut in the support plate 13 as shown in FIG. The slits may be provided concentrically (FIG. 4a) or linearly (FIG. 4b). The slit width is such that in a stationary state such as when the tank is filled with the polymer gel carrier, the polymer gel carrier can pass through the slit to fill the space below the support plate 13 with the polymer gel carrier. It is preferable that the polymer gel carrier group has a size capable of forming a bridge on the slit of the support plate 13. The size of such a slit cannot be generally stated because it varies depending on the size of the polymer gel carrier, but for example, the slit has a width of 5 to 10 times the maximum size of the polymer gel carrier, and the pitch of the slits is It is desirable to have the same size as the width.

In the lower part of the denitrification section 5, there is provided a backwash air diffuser 8 for backflushing suspended solids and excess sludge accumulated between the polymer gel carrier groups in the denitrification section with air to expel them. ing. The backwash air diffuser 8 has a backwash line 1 from the compressor 9.
1 is provided via an air tank 10 and a backwashing air solenoid valve 12 that opens and closes by a timer, and is connected through the side wall of the processing tank 1.

Furthermore, a screen 14 is provided at the bottom of the processing tank 1 below the denitrification section 5, and the screen 1
A circulation line 15 (denitrification liquid water supply means) that circulates the circulating water that has passed through the denitrification unit 5 to the upper portion of the nitrification unit 4 is connected to the unit 4. The screen 14 is embedded in a gravel layer having a particle diameter of about 8 mm to 20 mm, which is larger than the mesh of the screen 14 spread on the bottom of the processing tank 1.
No. 4 clogging is prevented.

The circulation line 15 is provided with a detection end 22 of a redox potential measuring device and a circulating water solenoid valve 16. This circulating water solenoid valve 16 is closed by the timer of the backwash air solenoid valve 12 when the backwash air solenoid valve 12 is open, and is opened when the backwash air solenoid valve 12 is open, and the opening and closing of the backwash air solenoid valve 12 is performed. It is supposed to be the opposite of 12. An air supply pipe 31 branched from an air supply pipe 30 for supplying air from the blower 20 to the diffuser pipe 3 is connected to the circulation line 15 at the same level as the diffuser pipe 3 in the nitrification section 4. Due to the air lift effect, the circulating water that has passed through the denitrification section 5 circulates above the nitrification section 4. The tip of the circulation line 15 is opened above the nitrification section 4 so that the denitrification liquid is dropped onto the upper part of the nitrification section to entrain air.

The detection end 22 of the redox potential measuring device is preferably a platinum-silver / silver chloride inner electrode type composite electrode, and is preferably equipped with a cleaning mechanism in consideration of electrode contamination.

Next, the operation of the apparatus of the above embodiment will be described.
First, prior to operation, the treatment tank 1 is filled with a polymer gel carrier having activated sludge fixed therein. The activated sludge contained in the polymer gel carrier is a general sewage treatment plant or human waste treatment plant. It may be collected from a facility that uses a floating activated sludge method, such as activated sludge that is rich in nitrifying bacteria and denitrifying bacteria from a facility that biologically removes nitrogen. . As the polymer gel carrier, the collected activated sludge is concentrated from 2% to 8% by weight, and then mixed in an equal amount with an aqueous solution of 15 to 25% by weight of polyvinyl alcohol (saponification degree: 99.85% or more). -
After cooling to 5 ° C or lower, preferably -20 to -30 ° C, thawing, vacuum freeze-drying and the like to obtain the required properties can be preferably used.

The polymer gel carrier has a rectangular parallelepiped shape,
Various shapes such as cubes, cylinders and spheres can be used,
One side or diameter is 3 to 20 mm, preferably 5 to 1
It is preferably about 0 mm. For example, if the diameter is too small, for example, about 0.5 mm, the porosity in the tank is reduced, and in this embodiment, the pressure loss due to the downward flow of the denitrification section described later becomes large, which is not preferable.

As the polymer gel carrier, the above concentrated sludge is mixed in an equal amount with 10 to 15% by weight of an aqueous solution of a polymer such as ACAM or PEG, and a cross-linking agent (N, N'-methylenebisacrylamide) and a polymerization initiator (peroxide) 0.5 to 1 each of potassium sulfate) and a polymerization accelerator (dimethylaminopropionitrile).
It is also possible to use a polymer gel carrier prepared by various methods such as a method of adding about wt% and polymerizing at room temperature.

In order to fill the treatment tank 1 with the polymer gel carrier in which the activated sludge is entrapped and fixed, the treatment tank 1 is first filled with about half of the sewage, and then the nitrification section 4 is provided above the nitrification section 4 to raise the height of the treatment tank 1. The polymer gel carrier was charged by using a pump, a crane or the like which can be transported without abrasion or destruction of the molecular gel carrier, and in the denitrification section 5, the polymer gel carrier was filled and filled in the entire denitrification section. Then, the nitrification part 4 is filled so as to be 15 to 40% of the height of the nitrification part. In the denitrification unit 5, the polymer gel carrier is sequentially filled from the bottom through the slits of the support plate 13 to form a polymer gel carrier packed layer up to a required height. The above-mentioned “state in which the entire denitrification section is filled and filled” means that the filling rate in the denitrification section 5 (volume of filled polymer gel carrier / volume of treatment tank) is 60 to 70%, It means that the porosity of the packed bed of No. 5 is 30 to 40%. The filling rate varies because the filling rate changes depending on the shape and size of the polymer gel carrier. Similarly, in the nitrification section 4, “a state in which the height of the nitrification section is 15 to 40%” is a state in which the filling rate in the nitrification section 4 is 10 to 25%, and the void ratio in the nitrification section 4 is 75 to It means 90%.

When the treatment tank 1 is filled with the polymer gel carrier, the acclimation (also called acclimatization) operation is first performed. This acclimatization operation may be the same as the acclimatization method for general activated sludge treatment,
For example, a method of bringing the sewage into about 30% of the planned water flow in the same manner as in the actual operating condition to gradually bring the sewage amount close to the planned water amount, or from the beginning to make the sewage amount equal to the planned water amount and exactly the same as the actual operation. There is a method to do it in the state. By performing this acclimatization operation, nitrification and denitrification are promoted and favorable treated water can be obtained after an acclimatization period of 2 weeks to 1 month after the start of operation.

When the acclimatization operation is performed, as in the normal operation, the sediment and coarse floating substances are removed in a sand basin (not shown), and further, the ammonia nitrogen and the organic nitrogen in which a certain amount of floating substances are removed in the first sedimentation basin are removed. Sewage containing water is supplied from the wastewater pit 17 to the wastewater dispersion pipe 28 by the wastewater supply pump 18 via the wastewater supply pipe 19, and is dispersedly supplied into the denitrification section 5 from a plurality of downward wastewater supply ports of the wastewater dispersion pipe 28. To be done. The circulating water passing through the denitrification section 5 is always sucked downward by the screen 14 through the gravel below the denitrification section 5. That is, the circulating water solenoid valve 1 in the circulation line 15
6 is always open except for air backwashing of the denitrification section, and air is blown from the blower 20 through the air supply tube 31 to the same level as the diffuser tube 3 of the nitrification section 4 of the circulation line 15. Since it is supplied, the circulating water that has passed through the denitrification section 5 passes through the circulation line 15 due to the air lift effect, and the nitrification section 4
Falls above and entrains air into the nitrification section 4. The amount of water circulated from the denitrification unit 5 to the nitrification unit 4 is 2 to 5 times the amount of sewage supplied.

In the nitrification section 4, air is supplied from the blower 20 through the air supply pipe 30 and the diffuser pipe 3 only into the lower part of the draft tube 2, and the supplied air rises inside the draft tube 2, It is released to the atmosphere from the upper part of the nitrification section 4. With this flow of air, the nitrification unit 4
The treated water inside and the polymer gel carrier having activated sludge fixed inside flow up by moving up inside the draft tube 2 and down outside. Due to the upper shape of the baffle 26 provided at the boundary between the nitrification section 4 and the denitrification section 5, the polymer gel carrier P flows smoothly in the nitrification section 4 as shown in FIG. The hatched portion in FIG. 5 does not show the state in which the polymer gel carrier P is filled. The treated water in the nitrification section 4 flows down to the denitrification section 5 below, and a part thereof is sent to the polymer gel carrier separation section 6 on the side surface of the nitrification section 4. In the polymer gel carrier separation unit 6, the flow velocity is extremely slow, the polymer gel carrier is separated by sedimentation and returned to the nitrification unit 4, and the treated water is discharged from the treated water outlet 27 (FIG. 2) to the treated water passage 21. To be done.

When the above operation is continued and acclimation is carried out, in the nitrification section 4, nitrifying bacteria become the priority species inside the polymer gel carrier, and the nitrifying bacteria and organic matter-oxidizing bacteria coexist in the activated sludge. Nitrifying bacteria and organic matter-oxidizing bacteria also adhere to the outer surface of the polymer gel carrier. On the other hand, in the denitrification section 5,
Depending on the anaerobic environment, denitrifying bacteria become a priority species inside the polymer gel carrier, and the sludge is mainly converted to activated sludge, and the denitrifying bacteria also adhere to the outer surface of the polymer gel carrier. Further, in the denitrification section 5, sewage is supplied from the wastewater dispersion pipe 28 to the upper part of the denitrification section, and the circulating water passing through the denitrification section 5 has a downward flow, so that a layer is formed. A large amount of suspended matter in sewage is trapped between polymer gel carriers with a large specific gravity, and due to the floating organic substances and anaerobic environment, acid-producing bacteria mainly including facultative anaerobic bacteria inside and outside the polymer gel carrier A large amount of absolutely anaerobic bacteria also exists in the denitrification section 5.

In such a situation, the sewage is supplied to the upper part of the denitrification section 5, and the floating organic substances in the sewage continue to be captured in a large amount in the layer of the polymer gel carrier. An acid-producing bacterium that solubilizes the floating organic matter to produce an organic acid. Therefore, even if the suspended solids in the sewage are trapped in the polymer gel carrier layer, they are solubilized by the acid-producing bacteria, so that the amount of suspended organic substances trapped is maintained at a low level and a fixed amount. Without blocking 5
The pressure loss is kept low.

In the denitrification section 5, the absolutely anaerobic bacterium hydrolyzes a protein, which is one of the main organic compounds, into amino acids, and further causes a deamination reaction to remove organic nitrogen in sewage. In addition to converting to ammonia nitrogen, denitrifying bacteria, which are facultative anaerobic microorganisms, dissolve the soluble organic matter in the sewage and the organic acid produced by the acid-producing bacteria into the organic carbon source (hydrogen It is used as a donor) to reduce nitrite nitrogen or nitrate nitrogen generated and circulated in the nitrification section 4 described later to nitrogen gas. The nitrogen gas generated in the denitrification section 4 flows out of the water system as a gas while the treated water is circulating in the denitrification section 5 and the nitrification section 4.

The ammonia nitrogen and the remaining organic nitrogen in the denitrification section 5 are accompanied by the circulating water downstream of the denitrification section 5, and flow from the lower part of the denitrification section 5 to the nitrification section 4 via the circulation line 15. Circulated water is sent.

In the nitrification section 4, the organic nitrogen is converted into ammonia nitrogen by the organic substance oxidizing bacteria. The nitrifying bacterium, which has become a preferential species inside and outside the polymer gel carrier due to the production of carbon dioxide by the organic matter-oxidizing bacteria and the inflow of ammonia nitrogen from the denitrifying part 5 to prepare an environment in which the nitrifying bacteria can grow, is the denitrifying part. Ammoniacal nitrogen produced from the organic matter-oxidizing bacterium together with ammoniacal nitrogen from 5 is oxidized to nitrite nitrogen or nitrate nitrogen under aerobic conditions. The nitrification unit 4
The treated water discharged from the polymer gel carrier separation section 6 adjacent to the treated water channel 21 is guided to a settling tank (not shown), excess sludge entrained in the treated water is separated, advanced treatment is performed as necessary, and the treated sludge is discharged. To be done.

In the denitrification section 5, as is clear from the graph of FIG. 6 showing the relationship between the redox potential in the denitrification section, the nitrogen removal rate and the pressure loss in the denitrification section 5, the denitrification section 5
Lower redox potential from -200 mV to -400 mV,
When it is maintained preferably in the range of -200 mV to -300 mV, and more preferably in the range of -250 mV to -300 mV, the denitrification section 5 solubilizes the floating organic substances trapped in the layer of the polymer gel carrier by the downward flow. It becomes a growth environment in which the acid-producing bacterium that grows actively grows, the amount of the floating organic matter trapped becomes a remarkably low level, the pressure loss is maintained at a lower level, and the denitrification part 5 is prevented from being blocked. ,
Since the solubilized organic acid is used in the denitrification reaction, the nitrogen removal rate of the treated water is improved. From this phenomenon, in the device of the present embodiment, a device of the prior art, for example, an anaerobic device in which the lower part of a single tank is filled with a denitrifying bacteria-immobilized carrier as described in Japanese Patent Publication No. 1-37988 mentioned above. The denitrification section is an aerobic nitrification section filled with a nitrifying bacteria-immobilized carrier.In the denitrification section, circulating water circulates from the denitrification section to the nitrification section in an upward flow to denitrify. It was found that the power consumption related to the circulation of the water to be treated can be extremely small as compared with the conventional device that makes it easier to maintain the anaerobic property of the part and makes the pressure loss of the packed bed of the immobilized carrier as small as possible. .

The redox potential of the lower part of the denitrification section 5 is set to -400 m.
When operated at a value lower than V, sulfides are excessively generated, and more air than necessary to oxidize the sulfides in the nitrification section 4 must be supplied to the nitrification section 4. Further, the appearance of the treated water deteriorates because it remains as a colloid of sulfur in the treated water and becomes cloudy.

In the present embodiment, the redox potential of the lower part of the denitrification part 5 is measured by the detection end of the redox potential measuring device provided in the circulation line 15 which is a flow path through which the effluent from the denitrification part 5 passes. 22.

In order to maintain the redox potential of the lower part of the denitrification section 5 within the above-mentioned predetermined range, the backwash air diffuser 8 is connected to the air tank 1.
It is performed by ejecting air from 0 and adjusting the frequency (cycle) or backwashing time for backwashing the suspended solids and excess sludge accumulated between the polymer gel carrier groups of the denitrification unit 5. For example, when the redox potential of the water flowing from the lower part of the denitrification unit 5 is high (approaching to the + side), the backwash cycle is lengthened or the backwash time is shortened. When the redox potential is low, the backwash cycle may be shortened or the backwash time may be lengthened. Specifically, the backwashing air is stored in the air tank 10 by the compressor 9, the backwashing air solenoid valve 12 installed in the backwashing line 11 is opened by the timer, and the circulating water in the circulation line 15 is opened. Solenoid valve 16
Is closed by the above timer. As a result, the air in the air tank 10 is jetted into the denitrification section 5 from the backwash air diffuser 8 through the backwash line 11 and the backwash air solenoid valve 12, and the circulating water solenoid valve 16 is closed. Therefore, the backwashing air jetted into the denitrification section is prevented from escaping to the circulation line 15 via the screen 14 near the lower portion of the backwashing diffusion pipe 8.

The backwashing air jetted into the denitrification section 5 rises while keeping the polymer gel carrier layer in the denitrification section 5 in a fluidized state,
It is guided to the baffle 26 and gathers at the center of the lower part of the nitrification section 4, and is discharged to the atmosphere from the upper part of the nitrification section 4 through the inside of the draft tube 2 together with the aerated air from the diffuser tube 3 of the nitrification section 4.
As the backwash air moves in the polymer gel carrier layer in the denitrification unit 5, suspended substances and excess sludge trapped between the polymer gel carriers are entrained and rise to the nitrification unit 4. The part is discharged from the polymer gel carrier separating part 6 adjacent to the nitrification part 4 to the treated water channel 21, guided to a settling tank (not shown) and separated from the treated water. In addition, other suspended solids and excess sludge flow downward from the nitrification section 4 to the denitrification section 5
The polymer gel carrier is captured again.

It should be noted that about 5% to 10% of the polymer gel carrier moves between the nitrification section 4 and the denitrification section 5 by backwashing the denitrification section 5 with air. Since denitrifying bacteria coexist, the polymer gel carrier in the nitrification section 4 has a denitrification effect not only in nitrification, but the polymer gel carrier in the denitrification section 5 has a nitrification effect in addition to denitrification. , There is no problem in processing efficiency.

The turbulent flow generated by the above-mentioned air backwash promotes the inflow of the nitrification liquid into the denitrification section 5, and at the same time, the denitrification section 5
Since air is released into the air, the redox potential of the denitrification section 5 rises. Therefore, the backwash cycle of the air backwash (backwash frequency) and the backwash time may be appropriately selected so that the redox potential of the lower part of the denitrification unit 5 falls within the above-mentioned predetermined range. As a guide, backwash cycle from 1 hour to 4
It is advisable to select the time and backwash time from the range of 30 seconds to 2 minutes.

As a method of adjusting the redox potential of the lower part of the denitrification section 5, various methods other than the above-mentioned backwashing time can be adopted. For example, when the redox potential of the lower part of the denitrification part 5 is high, the amount of water passing from the nitrification part 4 to the denitrification part 5 is reduced, or the oxygen supply amount in the nitrification part 4 (aeration amount of oxygen-containing gas). The redox potential can be lowered by decreasing On the other hand, when the redox potential of the lower part of the denitrification part 5 is low, the amount of water passing from the nitrification part 4 to the denitrification part 5 is increased, or the oxygen supply amount in the nitrification part 4 (aeration amount of oxygen-containing gas). The redox potential can be increased by increasing

Next, the effect of the above embodiment will be described. In the present embodiment, the organic wastewater is supplied to the upper part of the denitrification section 5, and the discharged liquid from the lower part of the denitrification section 5 is circulated to the nitrification section 4 by an air lift in the circulation line 15 to flow through the denitrification section 5. Is set as the downward flow, a large amount of floating organic substances is captured in the layer of the polymer gel carrier by the downward flow of the denitrification section 5. This creates a growth environment in which acid-producing bacteria that solubilize buoyant organic matter actively proliferate, and the amount of buoyant organic matter that is trapped becomes a certain low level without increasing, resulting in low pressure loss. The denitrification part 5 is maintained and the clogging of the denitrification part 5 is prevented, and the solubilized organic acid is utilized for the denitrification reaction, and the nitrogen removal rate of the treated water is improved.

Particularly, the redox potential of the lower part of the denitrification section 5 is set to -2.
00 mV to -400 mV, preferably -200 mV to -300 mV, more preferably -250 mV.
To -300 mV, it is possible to efficiently solubilize buoyant organic substances by the acid-producing bacteria, and a hydrogen donor necessary for denitrification even in the treatment of wastewater with a small ratio of soluble BOD concentration to nitrogen concentration. It is possible to operate at high load without running out of the organic carbon source as described above, obtain a high nitrogen removal rate, and are suitable for treating sewage.

Therefore, in this embodiment, the pressure loss with respect to the downward flow in the denitrification section 5 can be made extremely small, the power consumption related to the air lift circulation is small, and the operating cost can be reduced. Further, in this embodiment, since the single treatment tank 1 having the nitrification section 4 at the upper part and the denitrification section 5 at the lower part is used, the site area of the processing equipment can be greatly reduced.

Moreover, the polymer gel carrier in the vicinity of the boundary between the nitrification section 4 and the denitrification section 5 in the one-tank system of the present embodiment is not limited to nitrifying bacteria but denitrifying bacteria in the polymer gel carrier of the nitrification section 4. ,
Not only denitrifying bacteria but also nitrifying bacteria are mixed in the polymer gel carrier of the denitrification unit 5 depending on the environment, and the polymer gel carrier of the nitrification unit 4 has a denitrifying effect as well as nitrification. Not only denitrification but also nitrification is recognized in the polymer gel carrier of the nitrification unit 5. Therefore, the polymer gel carrier near the boundary between the nitrification section 4 and the denitrification section 5 is about 5 to 10% per 1 to 4 hours.
There is no problem in processing efficiency even if mixed to some extent. Therefore, in the present embodiment, a mesh screen for partitioning the nitrification section and the denitrification section is not particularly necessary. Therefore, it is easy to fill the polymer gel carrier to be replenished at the beginning of the operation and during the operation, and the operation management is easy without any operational trouble due to the clogging of impurities in the sewage.

Further, in this embodiment, the amount of floating organic substances trapped in the layer of the polymer gel carrier of the anaerobic denitrification section 5 was adjusted to adjust the pressure of the polymer gel carrier layer of the denitrification section 5. In order to keep the loss constant, although the anaerobic denitrification part 5 is used, backflushing with air is performed, and the backflushing cycle or backflushing time is adjusted to denitrify in a short time. Since the redox potential of the part is adjusted, it does not affect other operating conditions, can be easily implemented, and is extremely easy to manage. Further, by providing the backwash air diffuser 8, it is possible to treat the organic wastewater containing a large amount of floating organic matter, which is convenient.

In the apparatus of the embodiment shown in FIG. 1, air diffusers 3 and 28 are used as air diffusers used when air is supplied to the nitrification section 4 and backwashing air is supplied to the denitrification section 5. However, other air diffusing means such as a sparger, a diffuser, and an air diffusing plate may be used. Also,
Although an example is shown in which the liquid discharged from the lower part of the denitrification unit 5 is circulated to the nitrification unit 4 by the airlift effect in the circulation line 15, a circulation pump can be installed in the circulation line 15 for circulation.

Further, in the apparatus of the embodiment shown in FIG. 1,
The support plate 13 for dispersing and supporting the polymer gel carrier group in the denitrification section 5 is provided in only one step, but in a treatment apparatus having a high denitrification section, a plurality of support plates are installed to increase the height. It is possible to prevent compaction of the molecular gel carrier and effectively reduce pressure loss in the denitrification section. In this case, the distance between the supporting plates is 1 m or less, preferably 80 cm or less, more preferably 50 cm or less.

In the apparatus of the embodiment shown in FIG. 1, the redox potential of the lower part of the denitrification section 5 is measured, and the detection end 22 of the measuring apparatus is provided in the circulation line 15 which is a flow path through which the effluent from the denitrification section passes. However, it does not matter if the redox potential is measured by sampling from the flow path through which the effluent from the denitrification section passes or by directly sampling the denitrification solution from the denitrification section.

For backwashing in the denitrification section 5, an oxygen-rich gas such as pure oxygen or an inert gas such as nitrogen gas may be used instead of air, if necessary, but the maintenance is easy. It is desirable to use air. When using an inert gas for backwashing,
Since the turbulent flow simply promotes the inflow of the nitrification solution to raise the oxidation-reduction potential, the multi-tank system is not effective and requires an inert gas storage facility or the like. In such a case, it is preferable to use oxygen-rich gas as a method of directly supplying oxygen to the anaerobic denitrification section.

The baffle 26 provided at the boundary between the nitrification section 4 and the denitrification section 5 in the processing tank 1 is not necessarily limited to the shape shown in FIG. For example, as shown in Figure 7,
An annular flat plate baffle 3 having a circular opening 32a in the center
2 may be provided on the inner wall of the processing tank 1. The central circular opening 32a of the flat plate baffle 32 has an inner diameter smaller than the inner diameter of the draft tube 2 located above the baffle 32.
The annular flat plate baffle 32 also smoothly flows the polymer gel carrier P in the nitrification section 4.

Further, as shown in FIG. 8, by filling the treatment tank 1 with the polymer gel carrier P in a slightly larger amount,
The baffle may be omitted. That is, the denitrification unit 5
The upper part of the polymer gel carrier-packed layer of 1 becomes concave due to the flow in the nitrification section 4, and has a shape similar to the upper surface shape of the baffle 26 in FIG. 1, and as a result, the height in the nitrification section 4 is the same as when the baffle 26 is installed. The molecular gel carrier will flow smoothly.

Baffle 26 in the apparatus of the embodiment of FIG.
The draft tube 2 and the polymer gel carrier separating section 6 are omitted, and the polymer gel carrier separating tank 33 as shown in FIG.
It is also possible to simplify the structure of the processing tank 1 by independently providing. That is, in the apparatus of FIG. 9, the treated water mixed with the polymer gel carrier is discharged from the outlet 40 provided in the upper part of the nitrification unit 4, and the separation tank 3 is connected via the pipe 41.
Introduced to 3. Here, the treated water and the polymer gel carrier are separated, the treated water is discharged from the treated water channel 21, guided to a settling tank (not shown), and the excess sludge entrained in the treated water is separated. After being given, it is released. The polymer gel carrier is returned to the nitrification section 4 of the processing tank 1 through the pipe 42. A mesh screen or the like (not shown) that allows the treated water and the excess sludge to pass but does not allow the polymer gel carrier to pass is attached to the outlet 40 to directly treat the treated water and the excess sludge discharged from the outlet 40. The polymer gel carrier separation tank 33 can be omitted.

Further, in the embodiment of FIG. 1, the polymer carrier on which the activated sludge is entrapped and fixed is held in the denitrification section 5 and the nitrification section 4, respectively. Instead of this, nitrifying bacteria are entrapped and fixed. It is also possible to use the polymer gel carrier and the polymer gel carrier entrapping and fixing the denitrifying bacteria. In the case of using these polymer gel carriers, when filling the treatment tank 1 with these polymer gel carriers, first, the polymer gel carriers in which denitrifying bacteria are entrapped and fixed are put into the treatment tank to remove the denitrification part. After the filling into 5 is completed, the polymer gel carrier in which the nitrifying bacteria are entrapped and fixed is charged and filled into the nitrification section 4 until the required filling rate is reached. However, as described above, only nitrifying bacteria do not always metabolize and proliferate in the denitrifying part in the nitrifying part. Various substrate components are contained in the inflowing wastewater, and various microorganisms that contribute to the substrate components inevitably enter from outside the system such as the wastewater or the atmosphere according to the substrate components. As a result, during the processing operation, various microorganisms coexist with nitrifying bacteria and denitrifying bacteria on the surface and inside of the polymer gel carrier depending on the environment of the nitrification part and the denitrification part. Furthermore, by backwashing operation in the denitrification section 5 during the treatment operation, a part of the polymer gel carrier, which entraps and fixes the nitrifying bacteria in the nitrification section 4, moves to the denitrification section 5, and is denitrified. A part of the polymer gel carrier entrapping and fixing the denitrifying bacteria in the part 5 moves to the nitrification part 4. In this case as well, priority bacteria suitable for the environment of the nitrification part and the denitrification part are It will grow in the polymeric gel carrier.
Therefore, after a while from the start of operation, even when the polymer gel carrier in which only nitrifying bacteria and denitrifying bacteria are entrapped and fixed is used, it is substantially the same as when the polymer gel carrier in which activated sludge is entrapped and fixed is used. It becomes a state. However, the use of the polymer gel carrier in which only nitrifying bacteria and denitrifying bacteria are entrapped and fixed has an advantage that the acclimatization period can be shortened to some extent.

Further, in the present invention, the nitrification section 4 and the denitrification section 5 are configured as independent nitrification tank 44 and denitrification tank 45 in place of the single processing tank 1 as shown in FIG. A device such as 10 can also be used. In this case, the effluent (denitrification liquid) from the bottom of the denitrification tank 45 is circulated to the nitrification tank 44 through the circulation line 15 equipped with the circulation pump 24, and the nitrification liquid in the nitrification tank 44 is piped from the top of the nitrification tank. It circulates to the upper part of the denitrification tank 45 by gravity via 46. Note that the denitrification liquid intake position in the nitrification tank 44 may be any position in the nitrification tank 44 because the nitrification liquid itself is flowing in the nitrification tank 44 by an aeration means or the like for maintaining aerobicity. .

In order to explain the features of the present invention more clearly, experimental examples relating to the present invention are shown below.

Experimental Example 1 As Experimental Example 1 of the present invention, the volume of the treatment tank was 1 m ^3.
A sewage treatment experiment was conducted using the same apparatus as shown in FIG. The support plate 13 of the denitrification section 5 of the processing tank 1 is shown in FIG.
Use the one with the linear slit shown in (b),
The slit width is 5 cm and the board width (pitch) is 5 cm.
The activated sludge to be entrapped and immobilized on the polymer gel carrier was the returned sludge collected from the sewage treatment plant where the biological nitrogen treatment method was carried out. That is, in this night soil treatment plant, a denitrification tank, a nitrification tank and a precipitation tank are sequentially provided, and floating activated sludge and water to be treated are circulated between the nitrification tank and the denitrification tank for biological nitrogen treatment. The returned sludge, which is rich in organic matter oxidizing bacteria, nitrifying bacteria and denitrifying bacteria, is collected,
Concentrated sludge obtained by concentrating the collected returned sludge to about 6% by weight was used. The polymer gel carrier includes the concentrated sludge obtained above and PVA-HC manufactured by Kuraray Co., Ltd. (saponification degree: 99.85).
% Or more) and mix it in an equal amount with a 20% solution.
This tray was cooled to −20 ° C., thawed and cut into a 7 mm × 7 mm × 4 mm rectangular parallelepiped by a cutting machine. The polymer gel carrier thus produced was filled in the denitrification section at a filling rate of 60% (full filling rate) and in the nitrification section at a filling rate of 20%.

Sewage from which sediment of 0.2 mm or more and coarse suspended solids was removed in the settling basin, and suspended solids of 30 μm to 50 μm or more in the settling basin was first passed through this device to dissolve dissolved oxygen in the nitrification section. The supply air amount was set to 10 times the sewage treatment amount (supply amount) so that the concentration became 2 to 4 mg / L, and the operation was performed under the operating conditions shown in Table 1. The backwashing of the denitrification part was performed by setting the backwashing time to 30 seconds and fixing the interval time (cycle) between the backwashing operations to 2 hours.

In Comparative Example 1, a sewage treatment experiment was conducted using an apparatus obtained by modifying the apparatus of Experimental Example 1 shown in FIG. 1 as shown in FIG. 11, the draft tube 2, the baffle 26, the support plate 13, and the backwash air diffuser 8 in the apparatus of FIG. 1 are eliminated, and the nitrification section 4 and denitrification section 5 of the treatment tank 1 are eliminated.
A wire netting screen 29 for partitioning the and is provided. Further, the position of the waste water supply pipe 19 is changed from the upper part to the lower part of the denitrification section 5, and a circulation pump 24 is provided in the circulation line 15 to remove dewatering from the lower part of the denitrification section 5 to the upper part of the nitrification section 4 in the apparatus of FIG. By changing the "nitrifying solution water supplying means" to "nitrifying solution water supplying means for supplying water from the upper part of the nitrification section 4 to the lower part of the denitrification section 5",
The flow inside has been modified to change from downward flow to upward flow. In Comparative Example 1, since the flow water in the denitrification section 5 was changed to the upward flow, the air was not backwashed in the denitrification section 5. The other polymer gel carriers, the filling rate of the polymer gel carriers in the denitrification section 5 and the nitrification section 4, and the operating conditions are the same as those in Experimental Example 1 (see Table 1).

In Comparative Example 2, a sewage treatment experiment was conducted using an apparatus obtained by modifying the apparatus of Comparative Example 1 shown in FIG. 11 as shown in FIG. In the apparatus of FIG. 12, the position of the treated water outlet 27 of the nitrification section 4 in the apparatus of Comparative Example 1 is raised upward, the volume of the treatment tank 1 is increased by 0.2 m ³ , and the denitrification section 5 is increased by the increased volume. And the packing layer 5b of the polymer gel carrier in which the acid-producing bacteria are entrapped and fixed is provided below (the previous stage) the packing layer 5a of the polymer gel carrier in which the same activated sludge as in Experimental Example 1 and Comparative Example 1 is entrapped and fixed. It is newly provided. That is,
Acid production produced by the same method as in Experimental Example 1 using concentrated sludge obtained by concentrating sludge in the acid fermentation stage rich in acid-producing bacteria in a sewage sludge treatment plant that is performing anaerobic digestion to a concentration of about 6% by weight A polymer gel carrier in which bacteria are entrapped and fixed is filled by the above-mentioned increase in volume to first form a packed bed 5b, and then the same activated sludge as in Experimental Example 1 and Comparative Example 1 is entrapped and immobilized on the packed bed 5b. The carrier is filled to form the packed layer 5a. The other polymer gel carriers, the filling rate of the polymer gel carriers in the denitrification section 5 and the nitrification section 4, and the operating conditions were the same as those in Comparative Example 2 except for the retention time in the denitrification section (see Table 1).

These devices were sequentially operated for about 2 months including the acclimatization period, and the quality of raw water and treated water in normal operation were analyzed. The results are shown in Table 2.

[0093]

As is clear from Table 2, in Comparative Example 1, denitrification was not promoted although nitrification proceeded, and a large amount of nitrate nitrogen remained in the treated water, resulting in a poor nitrogen removal rate.
On the other hand, in Comparative Example 2 and Experimental Example 1, the denitrification reaction was also promoted and good treated water quality was obtained. However, in Comparative Example 2, although the treatment efficiency was the same as that of Experimental Example 1, since the packed layer 5b of the polymer gel carrier in which the acid-producing bacteria were entrapped and immobilized was disposed, the tank volume increased 1.2 times. The filling rate of the nitrification part remains the same at 20%, but the volume of the filling ratio of the denitrification part at 60% increases.
The initial cost such as construction cost, polymer gel carrier manufacturing cost, etc. is increasing by almost 0%.

The wire mesh screens for partitioning the nitrification part and the denitrification part in Comparative Examples 1 and 2 were considerably clogged after about 2 months of operation, and it was observed that they would be clogged if operated for a longer period of time. Was done.

After this Experimental Example 1, a polymer gel carrier having the concentrated activated sludge fixed therein was used with a size of 7 mm.
10mm x 10m from a rectangular parallelepiped of x 7mm x 4mm
The experiment was conducted under the same conditions as in Experimental Example 1 except that the cuboid of m × 7 mm was used and the other device conditions and operating conditions were the same, but the size of the polymer gel carrier was 7 mm × 7 mm × 4 mm.
The same treated water quality as in Experimental Example 1 was obtained, and the nitrogen removal rate remained unchanged.

Experimental Example 2 As Experimental Example 2 of the present invention, the volume of the treatment tank was 1 m ^3.
Using the same apparatus as in Experimental Example 1 (see FIG. 1), the sewage having the same properties as in Experimental Example 1 was treated, the backwashing time of the denitrification section was fixed at 1 minute, and the backwashing operation and the backwashing operation were performed. Interval time (cycle)
The oxidation-reduction potential in the lower part of the denitrification section is changed in a stepwise manner by gradually changing the temperature in the range of 30 minutes to 6 hours, and the redox potential, the nitrogen removal rate of treated water, and the pressure loss in the denitrification section are changed. I investigated the relationship. The polymer gel carrier used, the filling rate of the polymer gel carrier in the denitrification section and the nitrification section, and the operating conditions were the same as in Experimental Example 1.

The redox potential of the lower part of the denitrification part was measured by using a non-leak platinum-silver / silver chloride inner electrode type composite electrode (6397 type) manufactured by Electrochemical Instruments Co., Ltd. and provided in the circulation line 15. The measurement was performed by measuring the redox potential of the water flowing from the lower part of the denitrification section at the detection end 22.

The pressure loss in the denitrification section is based on the head pressure when the same amount of circulating water as the operating condition is circulated before filling the polymer gel carrier with a pressure gauge provided in the circulation line near the denitrification section. The difference between the water head pressure and the measured water head pressure when the redox potential was measured during the sewage treatment in which the polymer gel carrier was filled was displayed.

The results are shown in the graph of FIG. As is clear from this graph, the redox potential at the bottom of the denitrification section is-
200 mV to -400 mV, especially -200 mV-
300 mV range, and -250 mV to -300
When the value is mV, the pressure loss is lower and the nitrogen removal rate is higher than the value in the range of −100 mV to −150 mV, which is the target value for maintenance of the conventional denitrifying part of floating activated sludge. There is. Therefore, if the oxidation-reduction potential is maintained within the above range, the amount of floating organic substances trapped between the polymer gel carrier groups in the denitrification part becomes a significantly low level, and the pressure loss is maintained at a lower level. At the same time, it is understood that the solubilized organic acid is utilized in the denitrification reaction and the nitrogen removal rate of the treated water is improved.

Experimental Example 3 As Experimental Example 3 of the present invention, the volume of the treatment tank was 1 m ^3.
A sewage treatment experiment with the same properties as in Experimental Example 1 was performed using the same apparatus as in Experimental Example 1 above. As the one to be entrapped and fixed inside the polymer gel carrier, the concentrated sludge used in Experimental Example 1 was not used as it was, but entrapped and fixed after the following acclimation operation. That is, a denitrification tank, a denitrification sedimentation tank, a nitrification tank, and a nitrification sedimentation tank are sequentially installed.The sludge separated in the denitrification sedimentation tank is returned to the denitrification tank, and the sludge separated in the nitrification sedimentation tank is returned to the nitrification tank. Then, using a device for acclimation that circulates only the nitrification solution from the nitrification settling tank to the denitrification tank, the denitrification tank and the nitrification tank of this apparatus are collected at the same human waste treatment plant as in Experimental Example 1. The returned sludge was charged, the sewage was introduced into the denitrification tank as raw water, and the acclimatization operation was performed for 1 month. After the acclimation operation, the acclimatized activated sludge in each of the denitrification sedimentation tank and the nitrification sedimentation tank was concentrated to about 6% by weight, and the concentrated sludge was entrapped and fixed inside the polymer gel carrier in the same manner as in Experimental Example 1. , A polymer gel carrier in which the activated sludge mainly composed of denitrifying bacteria in the denitrification settling tank is immobilized, and a polymer gel carrier in which the activated sludge in which the nitrifying bacteria and the organic matter oxidizing bacteria are mixed in the nitrification settling tank is fixed. Manufactured. The polymer gel carrier having activated sludge mainly composed of denitrifying bacteria immobilized in this way was filled in the denitrification section of the treatment tank used in this experiment at a filling rate of 60% (full filling rate). The polymer gel carrier, which was filled with and immobilized with activated sludge in which nitrifying bacteria and organic matter-oxidizing bacteria were mixed, was filled in the nitrifying part of the treatment tank so that the filling rate was 20%.

Using this treatment tank, operation was carried out under the same operating conditions as in Experimental Example 1 for about 1 month, and water quality analysis of raw water and treated water during normal operation was carried out. The results are also shown in Table 2. As is clear from Table 2, as in Experimental Example 3, a polymeric gel carrier having acclimated activated sludge mainly composed of denitrifying bacteria fixed therein and a acclimated activated sludge mainly composed of nitrifying bacteria fixed therein Even when the molecular gel carrier was used, the same water quality was obtained as when the polymer gel carrier in which activated sludge was fixed as in Experimental Example 1 was used, and the nitrogen removal rate was not changed. Therefore, also from this, it can be seen that, in the inside of the polymer gel carrier, a microbial group suitable for the environment is mixed and retained by acclimatization, actual operation, etc., depending on the environment of the nitrification section and the denitrification section.

[0103]

According to the present invention, a polymer gel carrier having a larger specific gravity than water in which activated sludge is entrapped and fixed is held in the nitrification section and denitrification section, or in a specific gravity in comparison with water in which nitrifying bacteria are entrapped and fixed. The large polymer gel carrier is held in the nitrification section, and the polymer gel carrier having a larger specific gravity than the water in which the denitrifying bacteria are entrapped and fixed is held in the denitrification section, and the organic wastewater is supplied to the upper part of the denitrification section, Moreover, since the circulating water passing through the denitrification section is made downward flow, a large amount of floating organic matter is trapped in the layer of the polymer gel carrier by the downward flow of the denitrification section. This creates a growth environment in which acid-producing bacteria that solubilize the floating organic matter actively grow, and the amount of the floating organic matter that has been captured is solubilized to a certain low level without increasing,
The low pressure loss is maintained, the denitrification part is prevented from being blocked, and the organic acid produced by the solubilization is utilized in the denitrification reaction, so that the nitrogen removal rate of the treated water is improved.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a one-tank type processing apparatus according to the present invention.

FIG. 2 is a longitudinal sectional view showing a part of the apparatus of FIG. 1 in an enlarged manner.

3 is a perspective view showing an example of the shape of a baffle used in the apparatus of FIG.

4 is a plan view showing an example of the shape of the polymer gel carrier support used in the apparatus of FIG.

5 is an enlarged vertical sectional view showing the vicinity of a boundary between a nitrification section and a denitrification section of the apparatus of FIG.

6 is a graph showing the relationship between the redox potential in the lower part of the denitrification section, the nitrogen removal rate of treated water, and the pressure loss in the denitrification section in the apparatus of FIG.

FIG. 7 is a vertical cross-sectional view showing, in an enlarged manner, another embodiment near the boundary between the nitrification section and the denitrification section of the apparatus of FIG.

8 is a vertical cross-sectional view showing, in an enlarged manner, yet another embodiment near the boundary between the nitrification section and the denitrification section of the apparatus of FIG.

FIG. 9 is a vertical sectional view showing another embodiment of the one-tank type processing apparatus according to the present invention.

FIG. 10 is a vertical sectional view showing an embodiment of a two-tank type processing apparatus according to the present invention.

11 is a vertical cross-sectional view showing an example of a conventional processing apparatus used in Comparative Example 1. FIG.

FIG. 12 is a vertical cross-sectional view showing an example of a conventional processing apparatus used in Comparative Example 2.

FIG. 13 is a vertical sectional view showing an example of a conventional processing apparatus.

[Explanation of symbols]

1: Treatment tank 2: Draft tube 3: Air diffuser
4: Nitrification part 5: Denitrification part 6: Polymer gel carrier separation part 8: Backwash air diffuser 13: Support plate 15: Circulation line 19: Waste water supply pipe
21: Treatment channel 22: Detection end of redox potential measuring device 26: Baffle
28. Waste water dispersion pipe 33: Polymer gel carrier separation tank

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takamasa Oki Inventor Takamasa Oki 27 Shinisogo-cho, Isogo-ku, Yokohama-shi, Kanagawa Incorporated company Niigata Iron Works Yokohama Development Center (72) Inventor Mitsunori Yumoto Shinisogo, Isogo-ku, Yokohama-shi, Kanagawa 27, Machi Incorporated company Niigata Iron Works Yokohama Development Center (72) Inventor Saburo Ozawa 1-9-3 Kamatahonmachi, Ota-ku, Tokyo Incorporated company Niigata Iron Works Engineering Center

Claims (9)

[Claims] 1. A method for treating organic wastewater in which nitrogen is biologically removed from the organic wastewater by circulating water between the nitrification section and the denitrification section. The polymer gel carrier having a large specific gravity is held in the aerobic nitrification section and the anaerobic denitrification section, respectively, and the organic wastewater is supplied to the upper part of the denitrification section, and the water flowing through the denitrification section is also supplied. The method for treating organic wastewater is characterized by downflowing. 2. A method for treating organic wastewater in which nitrogen is biologically removed from the organic wastewater by circulating water between the nitrification section and the denitrification section. The polymer gel carrier with a large specific gravity is held in the aerobic nitrification section,
Further, a polymer gel carrier having a higher specific gravity than water having denitrifying bacteria fixed therein is held in the anaerobic denitrification section, and organic wastewater is supplied to the upper part of the denitrification section and passes through the denitrification section. A method for treating organic wastewater, characterized in that the circulating water is a downward flow. 3. The redox potential of the lower part of the denitrification section is set to −20.
The method for treating organic wastewater according to claim 1 or 2, wherein the method is maintained in the range of 0 mV to -400 mV. 4. An anaerobic denitrification unit holding a polymer gel carrier having a specific gravity higher than that of water in which activated sludge is fixed, and an aerobic nitrification unit holding the polymer gel carrier,
A wastewater supply port provided in the upper part of the denitrification section for supplying organic wastewater, a nitrifying solution water supply means for supplying water from the nitrification section to the upper part of the denitrification section, and a water supply from the lower part of the denitrification section to the nitrification section. An apparatus for treating organic wastewater, characterized in that it is provided with a denitrification liquid water supply means so that the circulating water passing through the denitrification section becomes a downward flow. 5. An anaerobic denitrification unit holding a polymer gel carrier having a higher specific gravity than water having denitrifying bacteria fixed therein, and a polymer gel carrier having a higher specific gravity than water having nitrifying bacteria fixed therein. An aerobic nitrification section holding the polymer gel carrier, a wastewater supply port provided on the upper part of the denitrification section for supplying organic wastewater, and a nitrification section for feeding water from the nitrification section to the upper part of the denitrification section. An organic wastewater characterized in that a liquid water supply means and a denitrification liquid water supply means for supplying water from the lower part of the denitrification section to the nitrification section are provided so that the circulating water passing through the denitrification section becomes a downward flow. Processing equipment. 6. An aeration means is provided in the treatment tank, and a polymer gel carrier having a specific gravity larger than that of water in which activated sludge is fixed is introduced into the treatment tank, and a portion below the aeration means is introduced into the treatment tank. A denitrification section filled with a polymer gel carrier, a nitrification section for flowing the polymer gel carrier above the diffusion means, and a wastewater supply port for supplying organic wastewater to the upper part of the denitrification section. An apparatus for treating organic wastewater, which is provided with a denitrification liquid water supply means for supplying water from the lower part of the denitrification section to the nitrification section to make a flow of water passing through the denitrification section a downward flow. 7. A denitrification section provided with an air diffuser in the treatment tank, and a portion below the air diffuser is a denitrification unit filled with a polymer gel carrier having a specific gravity larger than that of water having denitrifying bacteria fixed therein. With a nitrification part that flows a polymer gel carrier having a higher specific gravity than water with nitrifying bacteria fixed in the upper part above the means, a waste water supply port for supplying organic waste water is provided on the upper part of the denitrification part,
An apparatus for treating organic wastewater is provided with a denitrification liquid water supply means for supplying water from the lower part of the denitrification section to the nitrification section to make the flowing water passing through the denitrification section a downward flow. 8. The diffusing tube for backwashing the polymer gel carrier-filled layer of the denitrification section is provided below the denitrification section, as described in any one of claims 4 to 7. Organic wastewater treatment equipment. 9. The polymer gel carrier support formed with a gap larger than the diameter of the polymer gel carrier in the denitrification section is provided in one or more steps in the denitrification section. Item 9. The organic wastewater treatment device according to any one of items 4 to 8.