JP2001070983A - Wastewater treatment method and treatment device - Google Patents

Abstract

[57] [Problem] To promote the removal of nitrogen and phosphorus, reduce the amount of methanol used, improve the dewatering properties of excess sludge, reduce the amount of coagulant used for dehydration, and increase the growth rate. Provided is a treatment apparatus for treating wastewater by holding useful microorganisms having a low concentration in a reaction tank at a high concentration. SOLUTION: This wastewater treatment apparatus includes means (11) for decomposing a substance containing an organic fibrous material, and means (21) for solid-liquid separation of a decomposition product obtained by the decomposition processing. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the treatment of sewage and industrial wastewater.

[0002]

2. Description of the Related Art Conventionally, a biological treatment method using microorganisms represented by an activated sludge method has been used for water treatment of sewage and industrial wastewater. In this biological treatment, when removing nitrogen components in wastewater, first, ammonia nitrogen is oxidized to NO ₂ -N or NO ₃ -N by the action of nitrifying bacteria, and then NO ₂ -N or NO ₃ -N Has generally been reduced to N ₂ gas. Further, the biological treatment method of phosphorus is a method of removing phosphorus in wastewater by ingesting phosphorus into microorganisms, and specifically, is performed by alternately exposing microorganisms to an anaerobic state and an aerobic state. In this case, the microorganisms exhale phosphorus using an organic substance in an anaerobic state, while the microorganisms excessively ingest phosphorus into the body using an organic substance in an aerobic state. Utilizing such properties of microorganisms, methods for biologically treating phosphorus have been developed.
In the biological treatment of phosphorus, the higher the organic matter / phosphorus ratio of the influent, the higher the phosphorus removal rate.

[0003] As described above, organic substances are useful as a reducing agent for causing a reduction reaction of a denitrification reaction, and for improving phosphorus removal efficiency. Organic substances and methanol contained in waste water have been used as such organic substances that act as reducing agents. In addition, a method has been proposed in which sludge is decomposed in an anaerobic state to generate an organic acid, and the organic acid is used as a reducing agent (hereinafter referred to as Conventional Technique 1).

[0004] In the activated sludge method, microorganisms (activated sludge) and treated water are separated in a final sedimentation basin, and a part of the settled and separated sludge is subjected to dehydration treatment after concentration. In recent years, sludge dewaterability tends to decrease due to changes in dietary habits, etc.However, as a method of improving sludge dewaterability and reducing the water content of dewatered cake, waste paper is added to sludge to be dewatered before dewatering To improve the dewatering property (Japanese Unexamined Patent Publication No. 9-2
No. 16000 (hereinafter referred to as Conventional Technique 2) has been proposed, and some are being put to practical use. Also, a method of charging a granular carrier such as waste paper or wood chips into a reaction tank (Japanese Patent Application Laid-Open No. 11-010182;
) Has also been proposed.

There has also been proposed a method of subjecting organic fibers such as cellulose to biological treatment in an anaerobic state to generate alcohol or methane (hereinafter referred to as prior art 4).

[0006]

As described above, in the conventional method for removing nitrogen from wastewater using microorganisms, when removing nitrogen components in wastewater, NO ₂ -N or NO ₃ -N is converted to N _2.
This is a method of reducing the gas. Although a reducing agent is required to cause this reduction reaction, generally only organic substances contained in wastewater are insufficient as a reducing agent.
On the other hand, when methanol is used (added) as a reducing agent, the cost of methanol is required, which causes a problem that the processing cost increases.

Further, in the technology for anaerobically decomposing sludge as shown in the prior art 1, ammonia nitrogen and phosphoric acid are generated simultaneously with the organic acid accompanying the decomposition of sludge. Since most of the organic matter generated by the biological reaction is used for treating the ammoniacal nitrogen generated, the merits of the organic matter with respect to nitrogen removal are offset, and there arises a problem that the generated phosphorus needs to be removed.

[0008] In the technique shown in the prior art 2, although the water content of the dewatered cake is reduced and the amount of the coagulant required for dewatering is also reduced, it is necessary to refine the used paper when adding the used paper. A waste paper dissolution tank must be provided. In addition, this method is a technique applied to a sludge treatment system and the like, and is effective in reducing the water content of the dewatered cake and the amount of the coagulant used for dewatering, but it is effective in removing nitrogen and phosphorus in wastewater treatment. Has no effect on

The technique shown in the prior art 3 has the advantages of improving the dewatering property and the sludge concentration in the reaction tank, but the carrier is anaerobic or anaerobic when brought into the final sedimentation tank. It becomes a state. Such a condition is undesirable for aerobic microorganisms,
Aerobic microorganisms attached to and immobilized on a carrier, such as nitrifying bacteria, are greatly damaged. Therefore, the method of the prior art 3 does not achieve the high advantage of using the carrier, that is, the high concentration of nitrifying bacteria. Further, in this method, the used waste paper and wood chips are drawn out as excess sludge and subjected to dehydration treatment, and at this time, useful microorganisms immobilized on the carrier also flow out of the reaction tank at the same time. .

The advantage of using a carrier to immobilize microorganisms is that useful microorganisms having a low growth rate are retained on the carrier, and this advantage is due to the residence time of microorganisms (or solids in a reaction tank). (Generally SR
T: Solid Retention Time). In the technique described in the prior art 3, as described above, the carrier and the suspended sludge reach the final sedimentation basin at substantially the same ratio and are drawn out at substantially the same ratio. Furthermore, in order to obtain the merit of reducing the content of the dehydrated cake as described in the prior art 3,
A relatively large amount of fiber must be introduced. Specifically, the SRT is shortened because fibrous material of about 10% or more of the generated sludge solid content when not charged is required. Therefore, the advantage obtained by using the carrier is negated in the case of the prior art 3.

A method has been proposed in which the sludge concentration (MLSS) in the reaction tank is set higher to increase the SRT. In fact, the method using the microorganism-immobilized carrier developed so far does not allow the carrier to flow out of the reaction tank,
SRT has been increased by using a carrier separation means such as a screen. However, in the prior art 3, since the carrier flows out to the final sedimentation basin and the solids load in the final sedimentation basin increases by that amount, the effect of extending the SRT by increasing the MLSS is little or negligible. In general sewage treatment, the SRT is set to about 2 to 5 days, depending on the water temperature, and is set to 3 days or more in order to retain nitrifying bacteria. In the prior art 3, the retention time of the carrier in the reaction tank is about 2 to 5 days or less, which is almost the same as suspended sludge, and the reaction time for the organic fiber to undergo the decomposition reaction is short. In addition, the organic fiber is taken out. Furthermore, the process is not such that a large amount of microorganisms having the ability to decompose organic fibers are retained. In other words, microorganisms having the ability to degrade organic fibrous materials are generally anaerobic microorganisms having a small growth rate, but have a large growth rate in an aerobic state in a system having an aerobic reaction tank. Aerobic bacteria grow in large quantities. Therefore, in an aerobic state having an aerobic reaction tank, a microorganism capable of decomposing organic fibers cannot be a priority species. For this reason, since organic fiber is hardly decomposed, no organic matter is generated, and the effect of promoting nitrogen removal and phosphorus removal and the effect of reducing methanol consumption cannot be obtained.

As described above, a method of treating wastewater that promotes nitrogen removal and phosphorus removal and reduces the amount of methanol used has not yet been obtained. Furthermore, the improvement of dehydration of excess sludge, improvement of sludge separation / condensation, and reduction of the amount of flocculant used for dehydration have not been sufficiently achieved, and useful microorganisms with a low growth rate are placed in the reaction tank. At present, maintaining at a high concentration has not yet been achieved.

Accordingly, the present invention promotes the removal of nitrogen and phosphorus, reduces the amount of methanol used, improves the dehydration of excess sludge, reduces the amount of coagulant used for dehydration, and increases the growth rate. It is an object of the present invention to provide a method for treating wastewater capable of holding small useful microorganisms at a high concentration in a reaction tank.

Further, the present invention promotes the removal of nitrogen and phosphorus, reduces the amount of methanol used, improves the dehydration of excess sludge, reduces the amount of coagulant used for dehydration, and increases the growth rate. An object of the present invention is to provide a treatment apparatus for treating wastewater by holding small useful microorganisms at a high concentration in a reaction tank.

[0015]

Means for Solving the Problems To solve the above problems, the present invention provides a decomposition product obtained by subjecting a substance containing an organic fibrous material to a decomposition treatment, and converting the decomposition product into a liquid-based component and a solid component. A solid-liquid separation into a component mainly composed of a liquid, and then treating the waste water using the component mainly composed of the liquid.

The present invention also provides a wastewater treatment apparatus provided with a means for supplying a liquid-based component obtained by solid-liquid separation of a decomposition product of a substance containing an organic fibrous material.

Further, the present invention provides a wastewater treatment apparatus provided with a means for solid-liquid separation of a decomposition product of a substance containing an organic fiber.

Further, the present invention provides an apparatus for treating wastewater, comprising: means for decomposing a substance containing an organic fibrous material; and means for solid-liquid separation of a decomposition product obtained by the decomposition processing. .

Hereinafter, the present invention will be described in detail.

The method for treating wastewater of the present invention is characterized in that a decomposition product obtained by subjecting a substance containing organic fibrous material to decomposition treatment is separated into a solid and a liquid, and the separation is performed using a liquid-based component. It is a feature. The liquid-based component used in the present invention can be obtained from a separate facility or the like, or the liquid-based component can be used to solidify a decomposition product of a substance containing an organic fiber. It can be obtained by liquid separation.

That is, the wastewater treatment apparatus of the present invention is a means for introducing a liquid-based component obtained by solid-liquid separation of a decomposition product of a substance containing an organic fiber, Means for solid-liquid separation of a decomposition product of a substance containing Alternatively, the wastewater treatment apparatus of the present invention includes means for decomposing a substance containing an organic fibrous material, and means for solid-liquid separation of a decomposition product obtained by the decomposition treatment.

In the present invention, the means employed for decomposing the substance containing organic fibrous material is not particularly limited.
For example, a substance including an organic substance can be treated using any one of a biological action, a chemical action, and a physical action, or two or three of them. By such a treatment, at least a part of cellulose, which is a main component of the organic fiber, is decomposed to obtain a low-molecular-weight organic substance, and wastewater is treated using the organic substance, which is a decomposition product.

The decomposition products obtained by decomposing and reducing the molecular weight of the organic fiber are used for denitrification and dephosphorization reactions in wastewater treatment to promote nitrogen removal, improve the nitrogen removal rate,
The effect of reducing methanol and the effect of improving the phosphorus removal rate can be obtained.

Further, a part of the organic fiber (a part of cellulose, lignin, etc.) is dehydrated in the sludge treatment step without being decomposed, so that the efficiency of dehydration, stabilization, and water content of the dewatered cake are improved. The effect of reducing the rate and the effect of reducing the coagulant for dehydration are obtained.

Further, the improvement of the dewatering property and the decrease in the water content of the dewatered cake reduce the volume of the sewage sludge cake, and thus have an advantage in terms of handling such as transportation cost.
In addition, in the case of performing incineration at a later stage, there is a merit such as a reduction in auxiliary fuel or an increase in energy recovery.

In the present invention, as the organic fibrous material (raw material), waste paper, wood chips (including construction waste material), sawdust, rice hulls, garbage, and the like, and a mixture of two or more of these can be used. it can. However, for kitchen waste,
A high nitrogen and phosphorus component concentration is not preferred because the effect of the present invention is reduced. In addition, as long as the organic fiber concentration and the organic substance concentration are high and the nitrogen and phosphorus component concentrations are low, waste and wastewater generated from factories and offices can be used as raw materials.

Particularly, in the present invention, it is preferable to use a waste material containing an organic fiber as a main component, for example, waste paper or the like as the organic fiber. This has the effect of reducing the cost of treating waste materials, and is also effective in terms of the current social demands of recycling and zero emissions. In addition, in the case where used paper is used, it is confirmed that even in the case where it is supplied in the form of a few centimeters in a granular form, the state in the reaction tank is so complicated that almost no prototype is left, so that the organic type is used. The input form of the fibrous material is not limited at all. However, from the viewpoint of the reaction rate, it is preferable to make the finer in advance. Whether or not to perform the miniaturization process may be appropriately determined by comprehensively judging the effect to be obtained and the cost for the miniaturization process. For example, when waste paper is used as the organic fiber, a valper can be used as a finer and dispersing device.

As a chemical action for treating a substance containing an organic fibrous material, it is preferable to use ozone treatment. This is because, among the chemical treatments, the ozone treatment has been found to be particularly efficient. Other chemical treatment methods include a sulfuric acid decomposition method, a wet oxidation method, and a high temperature and high pressure decomposition method.

As a biological action for treating a substance containing an organic fibrous material, it is preferable to carry out a microorganism treatment or an enzyme treatment. This is because cellulose can be efficiently decomposed by using a microorganism or an enzyme having the ability to degrade cellulose.

The water temperature in the organic fibrous decomposition tank is 15
By setting the temperature in the range of from 0 ° C to 65 ° C, the decomposition of the organic fiber can be performed at a relatively high rate, but a higher reaction rate is preferably obtained in the range of from 25 ° C to 60 ° C. Advantages of heating (increase in reaction speed and consequent downsizing of reaction tank, reduction of stirring energy and site area associated with downsizing of reaction tank, etc.) and disadvantages (consumption of heating energy ) Can be compared on a case-by-case basis to determine whether to heat.

The treatment of the substance containing organic fibrous material is preferably performed while controlling the anaerobic degree of the reaction tank in which this treatment is performed. If the anaerobic degree in the reaction tank is too high, the organic matter may be decomposed to methane and diffused, so that such inconvenience is prevented.

The anaerobic degree is preferably controlled based on the dissolved oxygen concentration and / or the oxidation-reduction potential. These are useful as indicators of anaerobicity and can prevent the decomposition of organic matter into methane.

The control of the anaerobic degree is based on the input amount of the organic fiber to the step of treating the substance containing the organic fiber,
It can be carried out by controlling the amount of sludge withdrawn from the step of treating the substance containing organic fiber. Thereby, the anaerobic degree can be controlled by controlling the amount of solids, the amount of microorganisms and oxygen in the organic fibrous reaction tank in which the organic fibrous is decomposed. Alternatively, the control of the anaerobic degree can be performed by increasing or decreasing the volume of the reaction tank for decomposing the organic fiber. In this case, for example, a plurality of reaction tanks are provided, and the number of the reaction tanks to be used is changed as necessary, or the inside of the reaction tank is divided into several sections so that a used portion has an appropriate volume. Or by changing the liquid level of the reaction tank.

Further, the control of the anaerobic degree is performed by the step of treating the substance containing the organic fibrous material with an oxygen-containing gas,
It may be carried out by introducing at least one selected from the group consisting of ozone and peroxide. This can prevent the anaerobicity from becoming too high, and in particular, ozone and peroxide also have the effect of promoting the decomposition of organic fibers.

In addition, intermittently making the atmosphere aerobic for a short time is effective for preventing decomposition of organic substances by methane bacteria. This is because methane bacteria are absolutely anaerobic and are very susceptible to oxygen, whereas cellulolytic bacteria are more anaerobic but more resistant to oxygen than methane bacteria. . Therefore, by performing an operation to make the atmosphere aerobic intermittently for a short period of time, it becomes possible to seriously damage only the methane bacteria.
This concept is the same as that of pickling bran miso once a day. In the case of bran miso, the growth of anaerobic germs is suppressed by feeding oxygen in this way. However, if the time for maintaining the aerobic state is too long, not only methane bacteria but also cellulolytic bacteria may be damaged. Furthermore, in this case, various aerobic heterotrophic bacteria appear, which further degrades the degradation products of cellulose. Therefore, there is a problem even if the aerobic state is too long, and it is desired to select appropriately. The time for maintaining the aerobic condition and the frequency of the aerobic state vary depending on the operating conditions of the reaction tank (for example, temperature, solids residence time, solids concentration, etc.).
A time period in which the dissolved oxygen concentration is 0.05 mg / L or more may be provided once a day to about eight times a day, one minute or more per one time.

As a method for reducing the activity of methane bacteria, there is a method of lowering the pH to about 5 or less.

As described above, at least a portion of the organic fibrous material is decomposed, and the substance containing the decomposition product is divided into a solid-liquid portion and a solid-liquid portion. Separated. Of the components separated in this manner, the portion containing more liquid components is introduced into the step of treating wastewater. On the other hand, the portion containing more solid matter is introduced into the sludge treatment step provided after the wastewater treatment step.

Specifically, the step of treating wastewater can be performed in an anaerobic and / or anoxic reaction vessel, and the above-mentioned portion containing a larger amount of liquid components is treated in an anaerobic and / or anoxic state. It can be introduced into a reaction vessel in an oxygen state. Thereby, the decomposition product of the organic fibrous material can be effectively used for the denitrification reaction and the phosphorus removal reaction. When the decomposition products of organic fibrous materials are put into the aerobic reaction tank, the decomposition products undergo aerobic decomposition in the aerobic tank, and most of them are decomposed into carbon dioxide and water. In addition, there is a disadvantage that it is not used for the phosphorus discharge reaction of the denitrification reaction or the phosphorus removal reaction, but this can be prevented. In addition, the main component of the organic fiber is cellulose. Since cellulose is a molecule composed of carbon, hydrogen, and oxygen, the decomposed substance contains almost no nitrogen or phosphorus, and is generated by decomposition of the organic fiber. The problem of the prior art 1 in which the nitrogen load and the phosphorus load in the wastewater treatment increase due to the organic matter can also be solved.

Some or most of the portion containing more solids may be returned to the organic fibrous decomposition tank. Thereby, the residence time of the organic fiber in the organic fiber decomposition tank can be controlled.

Further, the type of organic fiber, the reaction conditions, or the input amount of organic fiber calculated from the inflow water quality and the required treated water quality, and the organic fiber input amount calculated from the required water content of the dehydrated cake It is preferable to match That is, when the decomposition rate of the organic solid waste is high, the amount of the organic substance instead of methanol increases, but the effect of reducing the water content of the dewatered cake is weakened, while the decomposition rate of the organic solid waste is reduced. If is low, the pattern is reversed. Here, it is necessary to ensure consistency between the amount of organic fibrous decomposed products required for the synthesis of methanol substitute organic material and the remaining amount of organic fibrous materials required for improving dehydration. After all, it is nothing but to control the decomposition rate of the organic fiber to a predetermined value. Operating factors and influencing factors for controlling the decomposition rate of the organic fiber to a predetermined value include temperature, degradability of raw materials, type and concentration of microorganisms, and reaction time. Assuming that the temperature is constant and the raw materials are constant, the most easily controllable item is the reaction time. The reaction time depends on the reaction rate, reaction tank volume,
Since it is a function of the rate of input of the raw materials (organic fiber and water) to the reaction tank, the required decomposition rate, the amount (rate) of the organic substance alternative to methanol and the amount (rate) of the undecomposed organic fiber are ), The volume of the reaction tank and the feed rate of the raw materials (organic fiber and water) to the reaction tank may be determined. If the temperature or the composition of the raw material can be changed, these can also be added to the control factor.

Further, 1) the stirring speed of the organic fibrous decomposition tank is controlled (reduced), and 2) the organic fibrous decomposition tank is intermittently stirred to be supplied to the solid-liquid separator. The solids concentration of the effluent of the fibrous cracking tank may be controlled. By adjusting the residence time of the organic fibrous material in the organic fibrous decomposition tank in this manner, the amount of the organic fibrous decomposed material required for the synthesis of the methanol-substituted organic matter and the amount required for improving the dehydration property are also required. And the remaining amount of the organic fibrous material can be balanced.

Furthermore, most of the undecomposed organic fiber is contained in the portion containing more solid matter, and is not introduced into the step of treating wastewater. For this reason, the SRT in the step of treating wastewater can be increased, and bacteria with a low growth rate such as nitrifying bacteria can be more stably retained. However, in some cases, a portion containing a larger amount of solids may be introduced into each reaction tank of the water treatment system, the first settling basin, the last ionization / concentration tank, and the piping connecting these.

Alternatively, the step of treating the wastewater can be carried out in an aerobic reaction vessel, and the portion containing a larger amount of the liquid component of the substance containing the decomposition product of the organic fibrous material is used.
It may be introduced into an aerobic reaction vessel. Organic substances are necessary in the aerobic reaction vessel for aerobic excess intake of phosphorus, and depending on the quality of the inflow water, the decomposition products are also introduced into the aerobic reaction vessel to reduce the phosphorus removal efficiency. Can be further improved in some cases.

As described above, in the wastewater treatment method of the present invention, of the substances containing organic fibrous decomposition products, the portion containing more liquid components is introduced into the wastewater treatment step. You. On the other hand, the part containing more solid matter is introduced into the sludge treatment system, and concentrated, dehydrated,
Perform incineration and other treatments. Before introducing such a portion containing more solids into a sludge treatment system or the like, a biological treatment or a physicochemical treatment may be performed to decompose the organic matter contained in the portion containing more solids. Good.

When the step of treating wastewater is performed in an aerobic reaction vessel, the aerobic reaction vessel preferably contains a microorganism-immobilized carrier. Thereby, the growth rate is small, and nitrifying bacteria that are difficult to maintain at a high concentration, such as ammonia oxidizing bacteria and nitrite oxidizing bacteria, can be maintained at a high concentration in the reaction vessel.
Further more efficient nitrogen component treatment is achieved. That is, improvement of the nitrogen removal rate, stabilization of nitrogen removal, and downsizing of the reaction tank are achieved. In this case, a portion corresponding to the introduction of a portion containing a larger amount of liquid material (more precisely, a portion of the inputted organic matter which is decomposed, re-synthesized by microorganisms and solidified, and a part of solid-liquid separation The undegraded portion that could not be removed flows out undegraded), the amount of sludge solids increases, and the SRT is slightly shortened as compared with the case where the portion containing more liquid material is not introduced. For this reason, there is a slight disadvantage in maintaining the nitrifying bacteria in the reaction tank at a high concentration. However, since the nitrifying bacteria are kept at a high concentration in the carrier by charging the nitrifying bacteria into the reaction tank, the efficiency of nitrogen removal as described above can be achieved.

The microorganism-immobilized carrier accommodated in the aerobic reaction vessel is preferably in the form of a hollow cylinder, and the aerobic reaction vessel has a microbial immobilization carrier with an opening of 2.0 mm or more. It is preferable to provide a carrier outflow prevention device such as a screen on the outflow side. Since the surface area per unit volume of the microorganism-immobilized carrier can be increased by using the hollow cylindrical microorganism-immobilized carrier, a large amount of nitrifying bacteria can be held on the carrier surface, and the shape of the carrier can be improved. The coefficient is small and the fluidity is high. Here, when a portion containing a larger amount of liquid substance (including a decomposition product of organic fibrous material and a part of undecomposed portion that could not be completely separated into solid and liquid) was introduced into the wastewater treatment process, the organic fiber It is desirable that the mesh width of the screen be as large as possible, since finely divided fibers may cause blockage of the screen as the quality is degraded (chemically, biologically, or physically). Practically, the mesh width of the screen is preferably 2 mm or more, more preferably 2.5 mm or more.
If the width of the screen is large, the size of the carrier must be large. In this case, since the specific surface area of the carrier also decreases, it is desired to employ a hollow-shaped carrier capable of increasing the specific surface area.

In the step of treating the organic fiber-containing substance, 1) a part or all of the liquid substance generated in the wastewater treatment step, or tap water, industrial water, miscellaneous water, or well water is treated with an organic substance. It is preferably introduced into a reaction tank for decomposing fibrous materials. Examples of the liquid substance generated in the wastewater treatment process include inflow water, return sludge, excess sludge, circulating water, concentrated sludge, concentrated process desorbed liquid, dewatered process desorbed liquid, sludge treated process return water, and filtration cleaning wastewater. Is mentioned. Since the decomposition of the organic fiber is performed in water or in a wet state, it is necessary to supply water for this purpose. In particular, when part or all of the returned sludge or excess sludge of the wastewater treatment process, circulating water, part or all of the influent water of the wastewater treatment process, and part or all of the treated water of the wastewater treatment process, organic Microorganisms, enzymes and the like are supplied from the outside to the reaction tank for decomposing the system fiber. These properties vary depending on the regional characteristics and the presence or absence of factory wastewater,
If an effect can be expected on the decomposition of organic fibers due to these properties, these are supplied. Conversely, if there are disadvantages, tap water, industrial water, miscellaneous water, well water, etc. may be used.

Alternatively, in the step of treating the substance containing an organic fibrous material, at least one of an organic fibrinolytic enzyme and a microorganism capable of decomposing organic fibrous material may be introduced.

A reaction tank for decomposing a substance containing organic fibrous materials requires microorganisms and enzymes capable of decomposing organic fibrous materials, and it is preferable that these are supplied at the start of the reaction. When introducing a part of the return sludge into the reaction tank for decomposing the organic fiber as described above, if these contain microorganisms capable of decomposing the organic fiber, particularly, In some cases, it is not necessary to introduce the enzymes and microorganisms described above. However, these additions at the start of the reaction are effective for promptly starting the reaction. Add only at the beginning of the reaction, or
Since the addition is continued or the amount of addition depends on the regional characteristics and the presence or absence of inflow of industrial wastewater as described above, consider the economics from the stability of the reaction and the obtained reaction rate for each case. So, you can decide. Also,
Livestock waste containing the stomach of cattle may be collected from the cattle slaughterhouse and introduced to introduce cellulolytic bacteria, in which case the wastewater treatment can also be performed.

[0050]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing the configuration of an example of the wastewater treatment apparatus of the present invention. In the illustrated wastewater treatment apparatus, first, an organic fiber reaction tank influent 12 and a substance 10 containing organic fiber are introduced into an organic fiber reaction tank 11. In the organic fibrous reaction tank 11, the substance 10 containing organic fibrous material is treated by at least one of biological treatment, chemical treatment, and physical treatment. Further, in the present invention, as the organic fiber,
Waste materials such as waste paper mainly composed of organic fibers can be used.

The decomposition of waste paper in the organic fibrous reaction tank 11 can be promoted by extracting the reaction product. When the reaction product is present at a high concentration, the reaction product becomes a factor inhibiting decomposition. In particular, it is desirable to avoid accumulation of high concentration of hydrogen in the organic fibrous reaction tank 11, and it is possible to remove hydrogen by degassing hydrogen gas by decompression treatment or stripping treatment. These processes need not always be performed continuously, and in many cases, it is sufficient to perform them intermittently.

By performing these treatments, a part of the volatile organic acid generated in the organic fibrous reaction tank 11 is also extracted. However, in most cases, the amount does not cause a major problem. If a problem arises, the volatile organic acid may be recovered with an alkali or the like.

When the oxygen-containing gas is blown into the organic fibrous reaction tank 11 in order to reduce the activity of methane bacteria, the effect of removing hydrogen as described above can be obtained. Further, the hydrogen-containing gas generated by the decompression treatment may be blown into an anaerobic tank and / or an oxygen-free tank of a water treatment system. By such an operation, hydrogen and volatile organic acids in the gas generated by the decompression treatment are used as a reducing agent in the water treatment system. After solid-liquid separation,
When only the solid is returned to the organic fibrous reaction tank, the reaction product is extracted on the liquid side, and the same effect, that is, the effect of extracting the reaction product to promote waste paper decomposition is obtained.

The organic fibrous reaction tank 11 may contain a microorganism-immobilized carrier. When such a carrier is contained, "organisms having organic fibrous degrading ability" having a low growth rate can be held in the organic fibrous reaction tank at a high concentration. As a result, advantages such as downsizing of the organic fiber reaction tank and stabilization of the reaction in the organic fiber reaction tank can be obtained.

As the shape of the carrier, a hollow cylindrical shape is preferable, but the effect can be obtained with other shapes. By using a hollow cylindrical carrier, there are advantages that the surface area per unit volume of the microorganism-immobilized carrier can be increased, and that the carrier has a small shape factor and high fluidity.

As the material of the carrier, any of a high molecular weight material and an inorganic material can be used. Examples of the polymer system include polyvinyl alcohol, polyethylene glycol, polypropylene glycol, polyacrylamide, polyvinyl fermal, polypropylene, polyethylene, vinylidene chloride, nylon, polyvinyl chloride, and mixtures thereof. System, sand, activated carbon, and minerals such as anthracite and zeolite. Further, wood chips or the like may be used.

An enzyme as well as a microorganism may be immobilized on such a carrier. At that time, polyvinyl alcohol,
Polyethylene glycol, polypropylene glycol,
And an enzyme can be immobilized inside a gel such as polyacrylamide.

Downstream of the organic fibrous reaction tank 11, an anaerobic tank 9, an oxygen-free tank 2, an aerobic tank 4, a sedimentation tank 7, a concentrator 15 and a dehydrator 18 are provided. A processing process is configured.
The order of the arrangement of the tanks and the like is not limited to the illustrated example.

The effluent of the organic fibrous reaction tank from the organic fibrous reaction tank 11 is subjected to solid-liquid separation by the solid-liquid separation device 12 and the solid-liquid separation unit 12 is used to separate the solid-liquid portion from the portion containing a large amount of liquid material containing little solid matter. It is separated into parts that contain more objects.
Thereafter, the portion containing more liquid components is introduced into the anaerobic tank 9 and the anoxic tank 2, and the anaerobic tank 9 contains the inflow water (wastewater) 1 to be treated and sludge from the sedimentation basin 7. A part is introduced as return sludge 13. The portion 23 containing more solids is introduced into the sludge treatment system for treatment. In FIG. 1, the dehydrator 18
, But may be introduced first into the concentrator 15 or into the settling basin (not shown). Prior to these introductions, the portion containing more solids may be treated by biological or physicochemical techniques. With these, the quality of the return water from the sludge treatment system can be improved. Further, as shown in the figure, the concentrated separated liquid 17 from the concentrating device 15 and the dehydrating device desorbed liquid 20 from the dehydrating device 18 may be returned to the anaerobic tank 9, but these are not necessarily required. In some cases, the concentrated separated liquid 17 and the desorbing liquid 20 are introduced into a dedicated treatment step, or may be initially introduced into a sedimentation basin or a sand basin.

The reaction proceeds in the anaerobic tank 9 under anaerobic conditions, and the effluent from the anaerobic tank 9 is introduced into the oxygen-free tank 2 together with the circulating liquid 3 which is a part of the effluent from the aerobic tank 4. . The reaction proceeds in the oxygen-free tank 2 under oxygen-free conditions, and the effluent from the oxygen-free tank 2 is introduced into the aerobic tank 4.

The aerobic tank 4 contains a microorganism-immobilized carrier 5, and a carrier outflow preventing (carrier separating) device 6 is installed at the outflow side of this tank. Is always retained. A part of the effluent of the aerobic tank 4 is used as the circulating liquid 3 as described above.
And the remainder is introduced into the sedimentation basin 7. As the microorganism-immobilized carrier 5 housed in the aerobic tank 4, those described above can be used. That is,
A microorganism-immobilized carrier similar to that contained in the organic fibrous reaction tank 11 can be contained in the aerobic tank 4. A screen is generally used as the carrier separation device 6, but the system is not particularly limited as long as it can separate the carrier and the effluent of the aerobic tank 4, and any device can be used. For the reason already described, the screen mesh width is practically 2 mm or more,
2.5 mm or more is preferable.

In addition, there is enough room on the site of the treatment plant,
When a large aerobic tank is provided and nitrifying bacteria can be maintained at a high concentration, it is not always necessary to use the carrier 5 in the aerobic tank 4.

In the sedimentation basin 7, the effluent introduced from the aerobic tank 4 is settled and separated to obtain sludge.
The sludge is introduced into the concentration device 15 as surplus sludge 14, and the remaining portion of the sludge is introduced into the anaerobic tank 9 as returned sludge 13. On the other hand, the supernatant liquid subjected to solid-liquid separation in the sedimentation basin 7 is discharged as treated water 8. The sedimentation basin 7 is for separating the sludge from the treated water. If the sludge can be separated from the treated water, other methods (floating separation, membrane separation, filtration, centrifugation, etc.) can be used. May be used.

In the thickening device 15 into which the excess sludge 14 has been introduced, the sludge is concentrated and introduced into the dewatering device 18 as the thickened sludge 16, and then subjected to the dewatering treatment to obtain the dewatered cake 19.
Is discharged as Further, the desorbed liquid 20 generated in the dehydration step 18 is returned and processed to the anaerobic tank 9 together with the separated liquid 17 generated in the concentration step.

The concentrating equipment 15 and the dewatering equipment 18 may be of various types, such as a centrifugal concentrator, a filtration concentrator, a floating concentrator, a belt press dehydrator, and a centrifugal dehydrator. A dehydrator, a filter press dehydrator, a rotary press dehydrator, or the like may be used. In addition, depending on the treatment facility, there is a case where the sludge treatment facility is not possessed, and the sludge is condensed or treated by a mobile sludge treatment facility. .

The main reactions in the above-mentioned process are a decomposition reaction and a depolymerization reaction of the organic fiber in the organic fiber reaction tank 11; a phosphorus discharge reaction in the anaerobic tank 9;
A denitrification reaction in the anoxic tank 2; and an organic matter decomposition reaction, a nitrification reaction, and a phosphorus absorption reaction in the aerobic tank 4.

The nitrogen components in the wastewater are converted into ammonia nitrogen and organic nitrogen into NO ₂ -N and NO ₃ -N by the action of nitrifying bacteria in the aerobic tank 4. Here, the nitrifying bacteria refer to both those that are suspended and those that are immobilized on the carrier 5. Thereafter, a part of the effluent from the aerobic tank 4 is circulated as circulating water 3 to the oxygen-free tank 2, where NO ₂ -N and NO ₃ -N are reduced to N ₂ gas in the oxygen-free tank 2. . The N ₂ gas thus obtained is released to the atmosphere, whereby nitrogen components in the wastewater are removed.

As a reducing agent in this reduction reaction, an organic substance contained in the inflow water 1 is used. Further, organic matter generated in the organic fibrous reaction tank 11 and introduced into the oxygen-free tank 2 also acts as a reducing agent. Phosphorus in wastewater is removed by the following actions of microorganisms.
First, microorganisms use organic matter in the anaerobic tank 9 to exhale phosphorus in the body, and then the microorganisms that exhale phosphorus mainly absorb more phosphorus in the body than the amount exhaled in the aerobic tank 4. Thus, the phosphorus in the wastewater is removed by absorbing the phosphorus in the wastewater into the body of the microorganism.

When the microorganisms use the organic matter in the anaerobic tank 9 to cause a reaction of discharging phosphorus in the body, the organic matter is required as an energy source. As this organic substance, an organic substance generated in the organic oxygen-containing reaction tank 11 and introduced into the anaerobic tank 9 is used.

Also, when the microorganisms that have discharged phosphorus absorb the phosphorus in the aerobic tank 4, the organic matter is required as an energy source. When the organic matter as the energy source is insufficient, a part of the organic matter, which is a decomposition product generated in the organic fibrous reaction tank 11, is introduced into the aerobic tank 4 to obtain the effect as the energy source. be able to.

In the present invention, nitrogen in wastewater is removed by the redox reaction as described above, and phosphorus in wastewater is removed by excessive intake of phosphorus. Furthermore, in the present invention, organisms proliferate with a biological reaction utilizing a substance produced by the decomposition of organic fibrous materials. At this time, the microorganisms ingest the phosphorus compounds and nitrogen compounds in the water. Thus, the phosphorus concentration and the nitrogen concentration in the treated water are further reduced.

In the organic fiber reaction tank 11, at least a part of the organic fiber is decomposed, but undecomposed organic fiber remains. In the present invention, the organic fibrous decomposition products generated in the organic fibrous reaction tank 11 are separated from undecomposed substances. Specifically, centrifugal separation, flotation separation, membrane separation, precipitation concentration separation, filtration separation, and the like can be used as the separation means. A coagulant may be added during solid-liquid separation. When the solid-liquid separation is performed in this manner, the liquid component is divided into a portion containing a larger amount of liquid components and a portion containing a larger amount of solids.
That is, a portion containing a large amount of components useful for a denitrification reaction or a phosphorus removal reaction can be introduced. Furthermore, by introducing the portion containing more solids into the sludge treatment system, the portion containing more solids is not introduced into the water treatment process,
The SRT in the water treatment system can be increased. This makes it possible to stably hold useful microorganisms such as nitrifying bacteria having a low growth rate.

Furthermore, the undecomposed organic fiber improves the dewatering property of the sludge, so that the water content of the dewatered cake 19 from the dewatering device 18 is reduced, and the cost of auxiliary fuel for incinerating the dewatered cake is reduced. There is also an advantage that it can be greatly reduced.
In addition, there is a merit that the amount of the coagulant for dehydration can be reduced as the dehydration property is improved.

In the present invention, the shape of the organic fibrous material 10 introduced into the organic fibrous reaction tank 11 is not particularly limited, and may be any of granular, powdery, thread-like, and paper-like shapes. . From the viewpoint of reaction efficiency and reaction rate, although organic fibers are more advantageous as finer,
In this case, cost, maintenance for treatment, etc. are required. Therefore, the input form of the organic fiber may be appropriately determined in consideration of the necessity and effect.

For example, when a substance containing a powdery organic fibrous material is used, it is preferable to disperse it in a liquid before putting it into the organic fibrous decomposition tank. Depending on the type and state of the organic fiber to be charged (dryness, whether or not it is charged with static electricity, etc.), there is a possibility that a lump may be formed at the time of introduction into the organic fiber decomposition tank. This lump is an image of cocoa that does not dissolve, and it is difficult to obtain a good contact state between the input organic fiber and microorganisms or enzymes, and the reaction efficiency of the decomposition reaction of the organic fiber decreases. There is.

Examples of the liquid in which the substance containing the powdery organic fibrous material is dispersed in advance include a part or all of the liquid substance generated in the wastewater treatment step, tap water, industrial water, miscellaneous water, well water and the like. Can be used. Examples of the liquid substance generated in the wastewater treatment process include inflow water, return sludge, excess sludge, circulating water, concentrated sludge, concentrated process desorbed liquid, dewatered process desorbed liquid, sludge treated process return water, and filtration cleaning wastewater. Is mentioned. Further, a dispersant may be added as necessary,
It is also possible to disperse using ultrasonic waves or the like.

Examples of organic fibrous materials include shredder waste generated in offices and the like, shredder waste compressed and formed, waste paper formed into granules, wood chips and rice husks, and the like. In the case of waste paper, if it is to be recycled as paper, it is usually necessary to separate it in advance. On the other hand, in the present invention, separation is not particularly necessary,
Currently it is the most difficult to separate and difficult to reuse as paper,
So-called mixed waste paper, which is a major problem, can also be used. The portion of the high-quality paper in the mixed waste paper contains a large amount of cellulose, which is decomposed and degraded to low molecular weight and used for removing nitrogen and phosphorus. On the other hand, the low-quality paper portion in the mixed waste paper contains a large amount of hardly decomposable components such as lignin, but the undecomposed portion contributes to the improvement of the sedimentation property, concentration property, or dewatering property of sludge.

Further, by pre-treating the organic fibrous material before being decomposed and depolymerized in the organic fibrous reaction tank 11, the reaction efficiency and the reaction speed can be improved. Examples of the pretreatment include an acid treatment, an alkali treatment, an ozone treatment, a peroxide treatment, a temperature treatment, an ultrasonic treatment, and a combination thereof. Regarding whether to perform these processes, the processing cost,
The necessity, effect, and the like of maintenance and management for the treatment can be comprehensively determined and appropriately determined.

The average residence time of the organic fibrous material 10 in the organic fibrous reaction tank 11 is 1 day or more, and preferably 5 days or more.
Days or more. This is because the growth rate of microorganisms capable of decomposing organic fiber is low, and such a residence time is required to keep such microorganisms in the reaction tank at a high concentration. This is because the decomposition rate of the system fiber is low and a long reaction time is required.
However, when the degradability of the organic fiber is high, the average residence time can be made within one day.

In order to increase the residence time of the organic fiber 10 in the organic fiber reaction tank 11, the following method can be adopted. 1) The organic fibrous reaction tank 11 is gently stirred, and the organic fibrous reaction tank 1 is stirred.
2) Provide an organic fiber outflow prevention device at the outlet of the organic fiber reaction tank 11 to reduce the outflow of decomposition products and undecomposed organic fibers from 1) 3) Organic fibers 4) The organic fibrous reaction tank 11 adjusts (reduces) the amount of the organic fibrous reaction tank inflow liquid 12 into the reaction tank 11 or adjusts (reduces) the sludge withdrawal amount.
Is a batch operation, and after the organic fiber is precipitated or floated, no extraction is performed from the side containing more undecomposed organic fiber, or the extraction amount is reduced. Extracting from the side containing less undecomposed organic fibrous material is extracting hydrogen and soluble decomposition products, which is a general principle of chemical and biological reactions. By extracting the reaction product in this manner, a reaction promoting effect can be obtained.

As a method of 1) to stir the organic fibrous reaction tank 11 gently, it is general to use a mechanical stirrer, but it is also possible to stir by blowing gas. Generally, the rate of biological decomposition of organic fibrous materials is more anaerobic (reaction in the absence of oxygen) or anoxic reaction (reaction in the absence of dissolved oxygen) than aerobic reaction. (Reaction in the presence of oxygen). Therefore, when agitating by injecting a gas, a gas having a low oxygen concentration is blown; the amount of the gas blown is suppressed to a minimum that can be stirred; the gas is blown intermittently; It is desired that the inside of the organic fibrous reaction tank 11 be maintained in an anaerobic state by a low apparatus (for example, an apparatus that generates coarse bubbles).

As a method of providing the organic fiber outflow prevention device at the outlet of the organic fiber reaction tank 11 in 2), a screen is used when the organic fiber is in a lump such as a granular state. it can. Further, a sedimentation or flotation facility can be provided by utilizing a specific gravity difference.

3) Adjustment (reduction) of the amount of the inflow water 12 into the organic fibrous reaction tank 11 and the reduction of the molecular weight of the organic fibrous and undecomposed components from the organic fibrous reaction tank 11 In order to adjust (reduce) the amount of extraction of sludge, it is necessary to perform an extraction operation at a stage where sludge is accumulated to some extent in the organic fibrous reaction tank. This is because undecomposed organic fibers generally accumulate in the organic fiber reaction tank 11. In addition, the input amount of the inflow water 12 can be reduced,
The residence time of the organic fiber in the organic fiber reaction tank 11 can be increased by setting the sludge withdrawal amount to a relatively low value.

When the hardly decomposable organic substances accumulate in the organic fibrous reaction tank 11, it is necessary to pull them out. Basically, it may be sent to the solid-liquid separator 21 by increasing the stirring speed. As another operation for extracting sludge containing undecomposed organic fibrous material, for example, a method of directly extracting hardly decomposable organic matter from the organic fibrous reaction tank 11 can be adopted. Or can be pulled out by a vacuum car or the like. The extracted sludge is introduced into the sedimentation basin 7 or the concentration device 15. Further, although not shown, the extracted sludge can be first introduced into the sedimentation basin.

In the case where the sludge extracted is not particularly particulate, it may be introduced into the anaerobic tank 9, the oxygen-free tank 2, or the aerobic tank 4. In some cases,
The balance between the mass of the organic fiber fed into the organic fiber reaction tank 11 and the amount of the solid matter containing the organic fiber flowing out of the organic fiber reaction tank 11 is not required, and there is no need to pull out the sludge. Sometimes. In addition, by adjusting the stirring intensity of the organic fibrous reaction tank 11, solids containing organic fibrous material can be discharged from the organic fibrous reaction tank 11, whereby the organic fibrous reaction tank 11 can be discharged. It is possible to adjust the amount of extracted sludge and the residence time of the organic fiber in the organic fiber reaction tank 11.

The amount of the organic fiber 10 introduced into the organic fiber reaction tank 11 varies depending on the water quality of the inflow water 1, the amount of water, and the required quality of the treated water 8. In general,
When the desired nitrogen concentration or phosphorus concentration of the treated water is low; when the BOD / nitrogen ratio or BOD / phosphorus ratio of the influent water is small; It is necessary to increase the amount of the fibrous material 10. When treating general sewage, the input amount is 1m of incoming sewage.
^{It is} about 10 to 500 g per ³ pieces. The volume of the organic fiber 10 to be charged can be determined from the amount of the organic fiber 10 to be charged, the decomposition rate, and the average residence time.

The organic fibrous material is decomposed and depolymerized in the organic fibrous reaction tank 11 by a biological technique such as a microbial reaction or an enzymatic reaction to mainly produce sugars, organic acids, or the like. When producing alcohol or the like, methane gas may be generated due to excessive decomposition and depolymerization of the organic fiber depending on the conditions. Under a condition in which methane gas is generated in a large amount and is diffused, saccharides, organic acids, alcohols, and the like that have been generated are wasted, and a methane gas generation reaction occurs in the organic fibrous reaction tank 11. There must be no conditions. For this purpose, there is a method in which the residence time of solids in the organic fibrous reaction tank 11 is adjusted, specifically, shortened, so that the methane-producing bacteria do not accumulate in the tank at a high concentration.

Further, since methane-producing bacteria are generally bacteria that are greatly damaged by the presence of oxygen, that is, obligately anaerobic bacteria, oxygen-containing gas is blown into the organic fibrous reaction tank 11 or peroxide or ozone is discharged. The introduction and the like can suppress the growth and activity of methane bacteria. DO (dissolved oxygen concentration) or ORP (redox potential) can be used as an index of the anaerobic degree. In particular,
The control by the oxidation-reduction potential is effective. It is effective to control the molecular weight of the organic fiber to be in a range from +50 mV to -250 mV, which is a range in which methanation hardly proceeds.

The organic fibrous material is decomposed by a microorganism or an enzyme (cellulase, etc.) capable of decomposing organic fibrous material.
Are preferably present, and it is desired to supply them to the reaction tank at the start of the reaction. When a part of the returned sludge or the like is introduced into the reaction tank 11 for decomposing the organic fiber as described above, if microorganisms capable of decomposing the organic fiber are included in these components, In some cases, it is not particularly necessary to introduce enzymes and microorganisms into the reaction tank. However, it is effective to add these at the start of the reaction in order to quickly start the reaction. Whether to add only at the start of the reaction, whether to always add the addition, not to add, or how much the amount to add depends on the regional characteristics, the presence or absence of inflow into the factory wastewater, and the like, as described above. In addition, the conditions for adding enzymes and microorganisms vary depending on the required degree of molecular weight reduction of organic substances and the water content of the dehydrated cake. Therefore, the addition of enzymes and microorganisms can be determined as appropriate in consideration of the stability of the reaction, the obtained reaction rate, and the like, and the economic efficiency.

Further, a carrier in which microorganisms, enzymes, and yeasts having organic fiber decomposing ability are immobilized may be charged into the organic fiber reaction tank 11. As a result, the effect of shortening the startup period of the system, the effect of stabilizing the reaction of the system, and the effect of reducing the size of the reaction tank can be obtained. When an immobilized carrier is used, it is particularly effective to increase the contact efficiency between the carrier and the organic fibrous material, and it is preferable that the organic fibrous material be pulverized and pulverized.

Further, nutrients (organic substances such as a nitrogen component, a phosphorus component, and peptone) and trace elements necessary for the growth of microorganisms having an organic fiber decomposing ability are added to the organic fiber reaction tank 11. Depending on the case, further improvement in efficiency may be recognized. Also, nutrients can be reinforced by adding sludge from the initial settling basin, excess sludge, returned sludge, industrial wastewater including nutrients, industrial waste, and the like.

The flow of FIG. 1 shows an example of the wastewater treatment apparatus of the present invention, and the present invention is not limited to this flow. The anaerobic tank 9, the anaerobic tank 2, the aerobic tank 4, the aerobic tank circulating liquid 3, the sedimentation basin 7, and the returned sludge 13 in FIG. 1 constitute a water treatment process. It is a typical sewage advanced treatment flow called the method. Even if the water treatment step is replaced with a treatment method other than the anaerobic anoxic aerobic method, the effects of the present invention can be obtained with almost no change. For example, when the flow of the water treatment step is the standard activated sludge method, the standard activated sludge method itself does not assume the flow of nitrogen removal or phosphorus removal due to excessive intake of phosphorus. The effect of the promotion effect is weakened. However, even in this case, a biological reaction utilizing substances produced by the decomposition of the organic fibrous material occurs, and the organism grows accordingly. At this time, the microorganisms ingest the phosphorus compounds and nitrogen compounds in the water into the living body. I do. Thus, the phosphorus concentration and the nitrogen concentration of the treated water are reduced. further,
All effects such as improvement of the dewatering property of excess sludge, reduction of the amount of coagulant used for dewatering, and improvement of sludge separation / concentration property are maintained without any change.

Further, the water treatment process in the apparatus shown in FIG. 1 includes a circulation nitrification denitrification method, an anaerobic-aerobic method, a Badenho method, a modified Badenho method, a step-flow type nitrification denitrification method, a nitrification-endogenous denitrification method, Almost all biological treatment flows such as an anaerobic-nitrification-endogenous denitrification method and the like can be replaced with the flow of the carrier charging method. In any case, the effect of the present invention is almost maintained. When these methods are adopted, the effluent of the organic fibrous reaction tank is discharged from a low-dissolved oxygen tank such as an anaerobic tank or an anoxic tank in the flow, or a tank that does not blow oxygen, or a microaerobic tank. At least one can be introduced. As described above, a part of the effluent of the organic fibrous reaction tank may be introduced into the aerobic tank in order to promote the absorption of phosphorus. In addition, when the water treatment step is performed in a batch operation, it is preferable to introduce the effluent of the organic fibrous reaction tank during a time period when the dissolved oxygen concentration is low, but it is not always necessary to limit the time period to only this time period.

According to the present invention, the organic fiber is basically decomposed in the organic fiber reaction tank 11, the decomposition product is separated into solid and liquid, and the decomposition product is used for a biological reaction. In addition to promoting removal of phosphorus and phosphorus, the use of organic fibrous undegraded substances is intended to improve the separation, concentration, and dewatering properties of sludge. Included in the scope of the invention.

In the above, the method of decomposing the organic fiber 10 by the biological action using microorganisms, enzymes and yeasts in the organic fiber reaction tank 11 has been described as an example. The technique is not limited to this. The organic fibrous reaction tank 11 is used for decomposing and lowering the molecular weight of the organic fibrous material. Therefore, any other than biological method can be used as long as it achieves this purpose. Techniques such as chemical treatment and physical treatment are included.

More specifically, examples of the chemical treatment include an acid treatment, an alkali treatment, an ozone treatment, a peroxide treatment, a temperature treatment, and a combination thereof. Treatment: a method of crushing organic fiber using a grinder or a mill.

The method of decomposing and reducing the molecular weight of organic fibers is as follows.
Inflow water quality, required treated water quality, cost, site area, required dewatered cake moisture content, and the like can be comprehensively determined and appropriately selected. Among the above-mentioned methods, when the ozone treatment is employed, the organic fiber can be decomposed and depolymerized in a low-cost and small-sized reaction tank. It is suitable. The amount of ozone to be added depends on the type of the organic fiber, the required decomposition rate, the ozone dissolution efficiency, and the like. Therefore, it is preferable to determine the amount of ozone by actually performing addition and analysis. When the organic fiber is degraded to a low molecular weight by the ozone treatment, but does not lead to decomposition into saccharides and organic acids, that is, when the decomposition product is low-molecular cellulose, the ozone treatment is performed at a later stage. An organic fibrous reaction tank 11 using a biological technique may be provided. Also,
Depending on the type of organic fiber to be decomposed, the biological technique may be arranged at the first stage and the ozone blowing may be arranged at the second stage. Thus, it is also possible to provide a plurality of organic fibrous reaction tanks 11 for decomposing and reducing the molecular weight of the organic fibrous material.

Further, the piping introduced into each tank does not need to be introduced directly into each tank, but may be combined with the piping introduced into the tank, mixed with the liquid, and then introduced into the tank.

[0100]

The present invention will be described in more detail with reference to specific examples and comparative examples.

First, in the flow shown in FIG. 1, a device for introducing the effluent (part containing more liquid components) from the solid-liquid separation device 21 into the anaerobic tank 9 and the oxygen-free tank 2 by half is provided. This was used to treat wastewater, and the result was set to Example 1. In Example 1, the aerobic tank 4 contained 7% of a hollow cylindrical carrier 5 made of expanded polypropylene having a specific gravity of 1.01, a length of 5 mm, an outer diameter of 4 mm, and an inner diameter of 3 mm based on the true volume, and the carrier flowed out. A wedge wire screen having a mesh width of 2.5 mm was installed at the outlet of the aerobic tank 4 as a preventive device 6. In addition, a continuous centrifugal separator was used as the solid-liquid separator 21.

Further, an apparatus similar to that of the above-described Example 1 was constructed except that the microorganism-immobilized carrier 5 was removed from the aerobic tank 4, and the wastewater was treated using the same apparatus. And

In Examples 1 and 2, the volume of the organic fibrous reaction tank 11 was set to 20 liters.

Further, in order to promote the removal of nitrogen and phosphorus and to compare the sludge separation, concentration and dehydration properties, Comparative Example 1 was used.
The wastewater treatment was performed by the following method as No. 4 to No. 4.

The wastewater is treated by an anaerobic anoxic aerobic method,
Comparative Example 1 was used. This method corresponds to the case where the organic fibrous reaction tank 11 and the solid-liquid separation device 2 are not installed in the second embodiment.

In the anaerobic anoxic aerobic method, waste water was treated by a method of mixing waste paper that had been refined before dehydration, to obtain Comparative Example 2. This method corresponds to a flow in which Conventional Technique 2 is further applied to the method of Comparative Example 1 which is an anaerobic anoxic aerobic method.

First, the mixed sludge of the sedimentation tank sludge and the excess sludge was subjected to acid fermentation, and then the wastewater was treated by a method of half-feeding the mixed sludge into the anaerobic tank and the oxygen-free tank to obtain Comparative Example 3. The aerobic tank 4 does not contain a carrier. This method is a flow in which Conventional Technique 1 is applied to an anaerobic anoxic aerobic method. Here, the volume of the acid fermentation tank was 300 liters.

In Comparative Example 4, waste water was treated by a method employing an anaerobic oxygen-free aerobic method in the reaction tank in the third technique of the prior art in which granular waste paper was charged into the reaction tank. The aerobic tank 4 does not contain a carrier.

The raw water used in the above Examples 1 and 2 and Comparative Examples 1 to 4 was the first settling pond effluent of a domestic wastewater treatment plant, and the measured values shown below were measured 10 times in 10 months. It is the average of the measurements. Items common to each treatment include inflow water quality, water temperature, inflow water flow rate (100 L / hr),
Oxygen-free tank 2 volume (300 L), aerobic tank 4 volume (200 L), final sedimentation tank water area load (100 m /
Day), Circulating water ratio (200%), Returned sludge ratio (50%)
It is. The amount of sludge withdrawn was set so that the aerobic tank 4 had a sludge concentration of 3000 mg / L only in Comparative Example 4, and in other cases (Examples 1, 2 and Comparative Examples 1 to 3) 4 was carried out so that the sludge concentration became 2000 mg / L.

Waste paper is used as the organic fibrous material 10. Specifically, shredder dust in an office office is 2 mm.
Those cut into corners were used. In Examples 1 and 2 and Comparative Example 4, 3.6 g / hr of waste paper was added to the organic fibrous reaction tank 11, and in Comparative Example 2, 1.8 g / h.
r equivalent waste paper was added before dewatering.

In the prior art 3, the introduced particulate organic material acts as a carrier and is withdrawn from the water treatment system to the sludge treatment system as a carrier. A 2 mm square shredder dust from a business office would quickly fall apart and not serve as a carrier. For this reason,
In Comparative Example 4, a shredder dust of a business office was cut into 2 mm square and compression molded into a 3 mm square shape, and the carrier was pulled out before the shape of the carrier was broken.

In each Example and Comparative Example, the total length was 2
A rectangular stirring blade having a height of 8 cm and a height of 8 cm is placed in the reaction tank 11.
It is installed from the top so that there is a clearance of 5 cm from the bottom, and the inside of the reaction tank is almost uniformly stirred 35r
Stirred at pm.

After treating wastewater according to Examples 1 and 2 and Comparative Examples 1 to 4, the quality of the treated water, the sedimentation and separation of sludge, and the water content of the dewatered cake were examined. The results obtained are shown in Table 1 below. Put together.

The sludge dewaterability was determined by determining the appropriate amount of the polymer flocculant to be added by a jar test, and then removing the sludge after flocculation and gravity dewatering between filter cloths of a belt press dehydrator using a pressure tester. After dehydration under pressure at 1.5 kg / cm ² for 1 minute, the moisture content of the dehydrated cake was measured and evaluated.

[0115]

[Table 1]

As shown in Table 1, in Examples 1 and 2, the treated water quality was clearly excellent in both TN and TP, and the water content of the dehydrated cake was also a low value. These effects are as follows: the introduction of organic substances accelerated the denitrification and dephosphorization reactions, the fact that only organic substances were added and the nitrogen component and the phosphorus component were not added, and undecomposed organic substances had a favorable effect on the dewatering properties of sludge. It has been brought about by the features of the present invention such as giving.

In particular, the microorganism-immobilized carrier 5 is
In this case, NH ₄ —N was completely removed as shown in the results of Example 1 containing NH ₄ -N
NO _x -N generated by the oxidation of
This is because nitrification bacteria were maintained at a high concentration by the introduction of the microorganism-immobilized carrier 5, and the denitrification reaction was promoted by the addition of organic substances generated by the decomposition of organic fibrous materials.

In Example 2, although the removal of NH ₄ —N was not complete, the removal reaction (removal of NO _x —N) generated due to the addition of the organic matter generated by decomposition of the organic fibrous material was carried out. Nitrogen reaction) is promoted. For this reason, NO _x -N in the treated water becomes a small value, and as a result, TN
Is a small value following the first embodiment.

On the other hand, in all of Comparative Examples 1 to 4,
The effect as in the present invention has not been obtained. In Comparative Example 1,
Both TN and TP in the treated water are high, and the water content of the dehydrated cake is also high. In Comparative Example 2, although the water content of the dewatered cake is slightly improved, the quality of the treated water is not much different from Comparative Example 1.

In Comparative Example 3, the effect of the addition of the organic matter appears in that there is almost no NO ₃ -N in the treated water, but the values of TN and TP are not necessarily low. This is because the nitrogen component and the phosphorus component generated by the decomposition of sludge flow into the treatment system together with the organic matter.

In Comparative Example 4, only a slight effect was obtained in reducing the water content of the dewatered cake, and the quality of the treated water was almost the same as in Comparative Example 1, and there was no significant change. This is because, under the conditions of Comparative Example 4, that is, under the condition that the carrier shape is maintained and the carrier is pulled out and the residence time cannot be sufficiently ensured, the generation of low molecular weight organic substances due to the decomposition of the organic fibers constituting the carrier Because there is almost no.

[0122]

As described above, according to the present invention, nitrogen removal and phosphorus removal are promoted, the amount of methanol used is reduced, the excess sludge is dewatered, the amount of coagulant used for dehydration is reduced. The present invention provides a method for treating wastewater, which can reduce the amount of microorganisms and keep useful microorganisms having a low growth rate at a high concentration in a reaction tank. According to the present invention, the use of methanol is reduced while promoting the removal of nitrogen and phosphorus,
In addition, by improving the dewatering properties of excess sludge, improving the separation and condensation properties of sludge, and reducing the amount of coagulant used for dehydration, the useful microorganisms with a low growth rate are retained at a high concentration in the reaction tank, A processing device for performing processing is provided.

In the present invention, a part of organic fibers such as waste paper containing almost no components such as nitrogen and phosphorus is decomposed, and the generated decomposition products are used for removing nitrogen and phosphorus in wastewater treatment. Since it can be used, advanced treatment of wastewater (nitrogen and phosphorus removal) is achieved, and undecomposed organic fibers improve the separation, concentration and dewatering properties of sludge. Also,
As compared with the method of adding methanol, there is obtained an advantage that the processing cost can be reduced. Further, when the microorganism-immobilized carrier is accommodated in the aerobic tank, the treatment efficiency of the advanced treatment is improved (the removal rate is improved and the volume of the reaction tank is reduced), and the treatment is stabilized. In addition, the use of waste paper, which is waste, is effective in terms of effective use of resources and waste disposal, and its industrial value is great.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of an example of a wastewater treatment apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inflow water 2 ... Oxygen-free tank 3 ... Aerobic tank circulating liquid 4 ... Aerobic tank 5 ... Carrier 6 ... Carrier outflow prevention device 7 ... Sedimentation tank 8 ... Treated water 9 ... Anaerobic tank 10 ... Input organic fiber 11 ... Organic fiber reaction tank 12 ... Organic fiber reaction tank inflow liquid 13 ... Returned sludge 14 ... Excess sludge 15 ... Concentrator 16 ... Concentrated sludge 17 ... Concentrator desorbed liquid 18 ... Dehydrator 19 ... Dewatered cake 20 ... Separation liquid of dehydrator 21 ... Solid-liquid separator 22 ... Part containing more liquid components after solid-liquid separation 23 ... Part containing more solid components after solid-liquid separation

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Kenichiro Mizuno 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term in Nihon Kokan Co., Ltd. 4D004 AA03 AA12 CA17 CA36 CA39 CC02 CC08 CC11 4D040 BB05 BB82 BB57 BB82 4D059 AA05 BE01 BE08 BE16 BE37 BE41 BE49 BE56 CA22 CA28

Claims (10)

[Claims] 1. After subjecting a decomposition product obtained by subjecting a substance containing an organic fibrous material to a decomposition treatment to solid-liquid separation into a component mainly composed of a liquid and a component mainly composed of a solid, the liquid is separated. A method for treating wastewater, wherein wastewater is treated using a main component. 2. A fibrous decomposing step of decomposing a substance containing the organic fibrous material, and a solid-liquid separation step of a decomposition product obtained in the fibrous decomposing step.
The method for treating wastewater described in 1. 3. The wastewater treatment method according to claim 1, wherein the substance containing the organic fiber is waste paper. 4. The method according to claim 1, wherein at least one selected from the group consisting of ozone treatment, sulfuric acid decomposition treatment, wet oxidation treatment, high-temperature high-pressure decomposition treatment, microorganism treatment, and enzyme treatment is used as the decomposition step. The method for treating wastewater according to any one of claims 3 to 7. 5. A wastewater treatment apparatus comprising: means for supplying a liquid-based component obtained by solid-liquid separation of a decomposition product of a substance containing an organic fibrous material. 6. An apparatus for treating wastewater, comprising: means for solid-liquid separation of a decomposition product of a substance containing an organic fibrous material. 7. An apparatus for treating wastewater, comprising: means for decomposing substances containing organic fibrous materials; and means for solid-liquid separation of decomposition products obtained by the decomposition processing. 8. The means for decomposing a substance containing an organic fibrous material includes at least one selected from an ozone treatment, a sulfuric acid decomposition treatment, a wet oxidation treatment, a high-temperature high-pressure decomposition treatment, a microorganism treatment, and an enzyme treatment. The wastewater treatment apparatus according to claim 7, wherein the wastewater treatment apparatus is used. 9. The wastewater treatment apparatus includes at least one of an aerobic treatment facility, an anaerobic treatment facility, and an anoxic treatment facility, and at least one of the treatment facilities includes: 9. The method according to any one of claims 5 to 8, further comprising a means for introducing a component mainly composed of a liquid obtained by solid-liquid separation of a decomposition product of a substance containing an organic fibrous material. Wastewater treatment equipment. 10. The wastewater treatment apparatus has a sludge treatment facility, and the sludge treatment facility mainly comprises a solid obtained by solid-liquid separation of a decomposition product of a substance containing an organic fibrous material. The wastewater treatment apparatus according to claim 9, further comprising a component introduction means.