JP7303643B2 - Water treatment method and water treatment equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water treatment method and a water treatment apparatus, and more particularly to a water treatment method and a water treatment apparatus suitable for application to water treatment for treating septic tank sludge and night soil sludge and discharging the treated water into a sewage system.

In order to discharge the treated water obtained by treating raw water containing septic tank sludge and night soil sludge into the sewage system, it is necessary to satisfy the sewage exclusion standards. It is known that the standards are more lenient than the release standards. For example, BOD (biochemical oxygen demand) is 10 mg/L, N (nitrogen) is 10 mg/L, and SS (suspended solids) is 10 mg/L as standards for discharge to public waters. Exclusion criteria are BOD 600 mg/L, TN 240 mg/L, SS 600 mg/L.

As a conventional method for treating sewage effluent, for example, a method of removing dust (screen residue) contained in night soil and the like, diluting it to the sewage disposal standard, and discharging the water is known. In this case, the dilution ratio is generally about 10 to 20 times, and the amount of diluted water and the amount of sewer discharge become excessive.

As another treatment method, there is a system in which night soil or the like is solid-liquid separated by a dehydrator, and the dehydrated separated liquid is diluted and discharged into the sewage system. In this case, the dewatered separated liquid has significantly reduced components such as BOD, SS, and nitrogen compared to the residual urine, so the dilution ratio can generally be about 3 to 8 times. Since the water quality fluctuates, there is a problem that the amount of dilution water also fluctuates greatly depending on the water quality.

Also, the method of solid-liquid separation of human waste using a dehydrator ends up discharging 4 to 9 times the incoming amount, so the effect of reducing the sewage discharge amount is limited. Since it is difficult to remove soluble components in solid-liquid separation, if night soil or the like contains a large amount of soluble components, the water quality of the dehydrated separation liquid may deteriorate, and it may be necessary to increase the amount of dilution water. In some cases, it may not be possible to satisfy the sewage exclusion standard due to regulations on the amount of discharged water.

As another method for more reliably reducing the amount of dilution water and the amount of discharged water, a method of combining solid-liquid separation and biological treatment can be considered. For example, Japanese Patent Application Laid-Open No. 61-50691 (Patent Document 1) describes a method in which the solid content obtained by solid-liquid separation of septic tank sludge is mixed with night soil sewage to perform flocculation treatment, and the separated liquid is biologically treated. Are listed.

JP-A-61-50691

In the method described in Patent Document 1, there is no description about the discharge destination of the biologically treated water, but since the BOD of the treatment liquid of Example 1 can be treated up to 10 mg / L or less, it can be discharged to public water areas. It can be inferred that the treatment method is based on the premise of the discharge of water.

However, as mentioned above, the sewage exclusion standards tend to be looser than the standards for discharge into public water areas, so for treated water discharged into the sewage system, it is not necessary to meet the water quality mentioned in Patent Document 1. It has not been. Therefore, it is desired to propose a more efficient and appropriate treatment method that meets the water quality standards for sewage discharge.

On the other hand, in the water treatment that combines solid-liquid separation and biological treatment as described in Cited Document 1, there is a problem that it is difficult to perform incomplete treatment to the extent that sewage disposal standards are met.

For example, when nitrification and denitrification treatment is performed as biological treatment, a method of treating, for example, about 60% of the nitrogen instead of the entire amount, or a method of nitrifying the entire amount of ammonium nitrogen contained in the dehydration separated liquid and then denitrifying only 60% of it. and other methods are conceivable.

However, when about 60% of the nitrogen is treated, about 40% of the nitrate nitrogen remains, so denitrification occurs again when the sedimentation tank becomes anaerobic in the latter stage, and the generated nitrogen gas causes the sludge to become sludge. In some cases, solid-liquid separation cannot be performed sufficiently in the sedimentation tank. If solid-liquid separation cannot be performed in the sedimentation tank, the MLSS (activated sludge concentration) of the nitrification/denitrification tank cannot be maintained, and the treatment itself deteriorates.

When nitrifying all the ammonium nitrogen contained in the dehydration separated liquid, the water tank capacity becomes excessive, the aeration air volume required for nitrification becomes excessive, and hydrogen donors such as methanol and ethanol required for denitrification are required. , etc., and the equipment and operating costs are excessive for the required treated water quality.

As another method, biological treatment using an activated sludge method may be used to perform rough treatment until the quality of the treated water falls below the sewage disposal standard, dilute the treated water, and discharge the treated water into the sewage system. In this case, it is possible to solve the above-mentioned problems caused by halfway biological treatment using nitrification and denitrification treatment by treating with a high BOD load that does not cause nitrification, but the activated sludge method An appropriate water tank capacity is required for biological treatment using .

In view of the above problems, the present invention provides a water treatment method and a water treatment apparatus that can more efficiently obtain treated water that satisfies the sewage disposal standard with a smaller amount of diluted water.

As a result of intensive studies by the present inventors in order to solve the above problems, at least a part of the separated liquid obtained by solid-liquid separation of the water to be treated containing at least one of septic tank sludge and night soil sludge, We have found that it is effective to carry out dilution treatment after performing a specific biological treatment.

In one aspect of the water treatment method according to the embodiment of the present invention, which has been completed based on the above knowledge, water to be treated containing at least one of septic tank sludge and night soil sludge is solid-liquid separated into separated sludge and separated liquid. and at least part of the separated liquid is subjected to biological treatment using a non-clogging biofilm method including at least one of the trickling filter method, fluid carrier method, rotating disk method, and fixed bed method. and diluting the biologically treated water obtained in the biological treatment so as to meet the sewage disposal standards.

In one embodiment of the water treatment method according to the embodiment of the present invention, the biological treatment includes a biological treatment tank for removing BOD in the separated liquid and a biological treatment tank for removing nitrogen in the separated liquid. are connected in parallel or in series for processing.

In another embodiment of the water treatment method according to the embodiment of the present invention, the biological treatment includes stepwise inflow of the separated liquid into biological treatment tanks connected in series in two or more stages.

In still another embodiment of the water treatment method according to the embodiment of the present invention, the biological treatment supplies the separated liquid to a trickling filter bed to aerobicly decompose BOD in the separated liquid and nitrify ammonia nitrogen. to obtain biologically treated water, circulate the biologically treated water through the trickling filter, place the carrier in a circulation tank containing the circulating water to be circulated through the trickling filter, and the microorganisms adhering to the carrier Including allowing the denitrification reaction to proceed.

In one aspect, the water treatment apparatus according to the embodiment of the present invention is a solid-liquid separation apparatus that separates water to be treated containing at least one of septic tank sludge and night soil sludge into solid-liquid separation into separated sludge and separated liquid. and a biological treatment tank in which at least part of the separated liquid is biologically treated by a non-clogging biofilm method including at least one of a trickling filter method, a fluid carrier method, a rotating disk method, and a fixed bed method. and a dilution tank for diluting the biologically treated water obtained by the biological treatment so as to meet the sewage disposal standards.

In another embodiment of the water treatment apparatus according to the embodiment of the present invention, a film-like carrier having a structure in which a separated liquid and oxygen permeate facing each other across a film surface is arranged in the biological treatment tank. including being

In still another embodiment of the water treatment apparatus according to the embodiment of the present invention, the film-like carrier comprises a support and a film supported by the support, the film has a loop shape covering the support, Separation liquid permeates from the outer surface of the membrane, oxygen permeates from the space formed on the inner surface of the membrane to the outer surface of the membrane, and openings are formed in the membrane for discharging sludge separated from the inner surface of the membrane to the outside of the space. including being

In still another embodiment of the water treatment apparatus according to the embodiment of the present invention, an inflow for stepwise inflow of the separated liquid into each of the biological treatment tanks including two or more stages of treatment tanks connected in series and control means for controlling the step ratio of the separated liquid flowing into the biological treatment tank based on the volumetric load of the biological treatment tank and the quality of the separated liquid or biologically treated water.

ADVANTAGE OF THE INVENTION According to this invention, the water-treatment method and water-treatment apparatus which can obtain the treated water which satisfies a sewage disposal standard more efficiently with a smaller amount of dilution water can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic showing the water treatment apparatus which concerns on 1st Embodiment. FIG. 4 is a cross-sectional view showing an example of a film-like carrier included in a water treatment apparatus according to a second embodiment; FIG. 4 is a side view showing an example of a film-like carrier included in a water treatment apparatus according to a second embodiment; It is a schematic diagram showing the water treatment equipment concerning a 3rd embodiment. It is a schematic diagram showing the water treatment equipment concerning a 4th embodiment. It is a schematic diagram showing the water treatment equipment concerning a 5th embodiment. It is a schematic diagram showing the water treatment equipment concerning a 6th embodiment. It is a schematic diagram showing the water treatment equipment concerning a 7th embodiment. It is the schematic showing the water treatment apparatus which concerns on the modification of 7th Embodiment. It is a graph showing the result of having confirmed the change of the BOD setting load of each tank at the time of using the water-treatment method of an Example.

<Water treatment method>
The water treatment method according to the embodiment of the present invention separates water to be treated containing at least one of septic tank sludge and night soil sludge into solid-liquid separation into separated sludge and separated liquid, and at least part of the separated liquid On the other hand, biological treatment is performed by a non-clogging biofilm method that includes at least one of the trickling filter bed method, fluidized carrier method, rotating disk method, and fixed bed method, and the biologically treated water by biological treatment meets the sewage exclusion standard. including diluting to fill.

(Water to be treated)
The water to be treated to be treated is not particularly limited as long as it contains at least one of septic tank sludge and night soil sludge. For example, when a mixture of night soil sludge and septic tank sludge is used as the water to be treated, it is preferable to separately separate the night soil sludge and the septic tank sludge.

(Solid-liquid separation)
Various solid-liquid separation apparatuses can be used for the solid-liquid separation treatment, but it is preferable, for example, to separate the solid-liquid into separated sludge and separated liquid using a dehydrator in terms of equipment and operation costs. Furthermore, it is more preferable to perform concentration treatment on the water to be treated before solid-liquid separation. As a concentration method, both gravity concentration and mechanical concentration are effective concentration methods.

By performing the concentration treatment with the addition of a polymer flocculant before the solid-liquid separation treatment, the sludge concentration (TS) of the thickened sludge can be concentrated up to about 10 to 12% by mass. If the thickened sludge that has been concentrated to a high concentration is further dehydrated using a dehydrator, dehydrated sludge with a low water content of 70% or less (separated sludge) can be obtained, resulting in a more significant sludge volume reduction. effect is obtained. Since the dehydrated sludge with a low moisture content is high in calories, it can be self-combusted without auxiliary fuel in incineration treatment, resulting in energy saving and low cost.

(biological treatment)
Biological treatments using the biofilm method can be broadly divided into those that require a periodical cleaning step of the carrier and those in which the amount of biofilm is autonomously controlled during the treatment. The former corresponds to the biomembrane filtration method and the like. The latter includes the trickling filter bed method, the fluid carrier method, the rotating disk method, and the fixed bed method (contact oxidation method).

Among them, as the biological treatment according to the embodiment of the present invention, it is preferable to use a type of biofilm method in which the amount of biofilm is autonomously controlled during treatment, which is herein referred to as "non-clogging type of biofilm method”. In particular, among the non-clogging biofilm methods, the trickling filter method and the fluid carrier method can be stably operated even at a BOD volume load of 1 kg-BOD/m ³ /d or more, and the site area is limited. valid when A specific example of the biological treatment included in this "non-clogging biofilm method" will be described below.

－Trickling filter method－
The trickling filter bed method is one of the aerobic biochemical treatment methods. The action of microorganisms attached to the surface of the filter media decomposes the organic matter in the water to be treated (separate liquid) that is sprayed, resulting in biological It is a method of obtaining treated water. In the trickling filter bed method, it is generally known that the surface of the biofilm becomes aerobic and the inside of the biofilm becomes anaerobic. Therefore, when the trickling filter is operated with a load that allows nitrification to proceed, the nitrification reaction proceeds on the surface of the biofilm and the denitrification reaction proceeds inside the biofilm. excellent in terms of

There are no particular restrictions on the specific configurations of the carrier, sprinkler section, etc. used in the trickling filter. Any material to which microorganisms can adhere can be used as the material of the carrier, and typical examples thereof include plastics and crushed stone. The shape of the carrier may be any shape such as plate-like, spherical, cylindrical, rectangular parallelepiped, and hollow. The filling rate of the carrier with respect to the volume of the reaction tank is preferably 40-80%, preferably 50-70%. In the case of a film-like carrier, it is preferable to fill the reaction vessel so that the surface area of the film is 0.05 to 0.15 m ² /m ³ with respect to the capacity of the reaction vessel.

In order to perform biological treatment more efficiently and stably, a structure in which the separated liquid after solid-liquid separation supplied to the trickling filter and the oxygen in the trickling filter face each other across the membrane face and permeate is required. It is preferable that the membrane-like carrier having

In the film carrier, the separation liquid supply side is an area rich in BOD and oxygen poor, while the oxygen supply side is an area rich in BOD and rich in oxygen. Therefore, it is possible to create conditions suitable for the denitrification reaction on the supply side of the water to be treated (separated liquid) while creating conditions suitable for the nitrification reaction on the oxygen supply side, so it is particularly excellent among various carriers. It is more suitable in terms of exhibiting the nitrogen removal performance.

On the other hand, in the case of a normal granular carrier, BOD, nitrogen, and oxygen are supplied to the biofilm on the carrier surface from the ^same direction. In some cases, the BOD is completely consumed by oxidation, making it difficult for the nitrification-denitrification reaction to proceed. In addition, the film carrier has the advantage of being able to operate stably without clogging even under high load conditions of 1.5 kg-BOD/m ³ /d or more, compared to treatment methods using carriers of other shapes. have. This is because the film-like carriers are arranged in the vertical direction, and the biofilm separated from the carriers is discharged out of the tank without clogging between the carriers.

Flow of the separated liquid after solid-liquid separation into the trickling filter is performed after being transferred above the trickling filter using a siphon or the like. For watering, the separation liquid may be watered over the entire filter bed, and any watering device such as a perforated plate, sprinkler type, spiral type nozzle, or self-propelled rotary watering machine can be used.

- Fluid carrier method -
The fluid carrier method is a method in which a carrier is placed in a biological treatment tank, and the carrier flows in the biological treatment tank to bring the microorganisms into contact with organic matter, oxygen, and the like in the water to be treated, thereby obtaining biologically treated water. A biological treatment tank using the fluid carrier method may be newly installed, or a carrier, an aeration device, etc. may be introduced into an existing storage tank or the like. The carrier used for the fluid carrier is not particularly limited, but the following are typical examples.

Any carrier may be used as long as the carrier adheres to the microorganisms and is fluidized by aeration. The material of the carrier may be, for example, any carrier that is fluidized by aeration, such as plastics (polyurethane (PU), polyethylene (PE), polyethylene glycol (PEG), polyvinyl alcohol (PVA)), wood chips, sand. , etc. are used. The shape of the carrier may be sponge-like, gel-like, solid-like, and the like. The shape of the carrier can be any shape such as spherical, cubic, cylindrical, and honeycomb. In particular, by using a bonded immobilized carrier that attaches microorganisms to the outer surface of the carrier, it is possible to attach microorganisms suitable for the environment in the biological treatment tank to the carrier, making it less susceptible to changes in the properties of influent water. Stable biological treatment can be performed. The filling rate of the carrier is preferably 20 to 40% from the viewpoint of fluidity and performance. A filling rate of 20% or more can retain a large amount of microorganisms in the tank, and a filling rate of 40% or less to create appropriate voids can maintain good fluidity. The BOD load in the fluid carrier method is preferably 0.5 to 5.0 kg-BOD/m ³ /d, preferably 1.0 to 3.0 kg-BOD/m ³ /d. The fluidized carrier method is suitable for using an existing activated sludge aeration tank.

－Rotating disk method－
In the rotating disk method, a part of the rotating disk is exposed to the water to be treated and the outside air to form a biofilm on the surface of the disk and decompose the organic matter in the water to be treated (separated liquid). It is a method of obtaining biologically treated water. Since no aeration or aeration is performed, there is no need to install a blower that requires air volume adjustment, and unlike the activated sludge method, there is no need to supply returned sludge, which is advantageous in that simpler equipment can be supplied. The BOD load in the rotating disk method is preferably 0.1 to 1.5 kg-BOD/m ³ /d, and if an excessive load is applied, microorganisms adhere excessively to the disk and the rotating shaft is damaged. Problems can occur.

There are no particular restrictions on the material and specific shape of the disk, and any device can be used. For example, as a material for the disk, styrene foam, plastic, vinyl chloride, water-resistant veneer, metal plate such as aluminum can be used. can.

-Fixed bed method (contact oxidation method)-
In the catalytic oxidation method, a fixed bed carrier is immersed in a reaction tank, and water to be treated is passed through while aeration is performed to form a biofilm on the carrier surface and remove organic matter from the water to be treated (separate liquid). It is a method of decomposing to obtain biologically treated water. Since treatment is performed using biofilms attached to the carrier, there is no need to control the amount of sludge by returning it, unlike the activated sludge method, and maintenance is easy. The BOD load is preferably 0.1 to 1.0 kg-BOD/m ³ /d, and when operated at a high load, the biofilm may enlarge and clog the contact material.

There are no particular restrictions on the material and specific shape of the carrier for the catalytic oxidation method, and any device can be used. As the material of the carrier, polyethylene, plastic, etc. can be used, and the shape can be any shape such as tube, string, net, plate, ball, and the like.

(Dilution ratio)
The biologically treated water obtained by the above biological treatment is sent to a dilution tank and mixed with dilution water to be diluted so as to meet sewage disposal standards. According to this embodiment, the dilution rate is typically 1 to 4 times, more typically 1 to 3 times, and further 1 to 2 times, so that the amount that satisfies the sewage removal standard can be obtained. can. Dilution may be done at all times or only when necessary to meet sewage rejection standards. As a result, more efficient and appropriate treatment can be performed in accordance with the water quality standards for sewage discharge with a smaller amount of dilution water than in the conventional method.

According to this embodiment, by performing the biological treatment described above, the biologically treated water may be treated to such an extent that the biologically treated water does not need to be diluted. In that case, at least part of the separated liquid is diluted with the biologically treated water after biological treatment using the non-clogging biofilm method including either the trickling filter method or the fluidized carrier method. Needless to say, the sewage can be discharged as it is without carrying out the

According to the water treatment method according to the embodiment of the present invention, the above-described non-clogging type is applied to at least a part of the separated liquid obtained by solid-liquid separation of the water to be treated containing at least one of septic tank sludge and night soil sludge. Dilution after biological treatment by the biofilm method makes it possible to obtain treated water that can be discharged into the sewage system more efficiently and stably with a small amount of diluted water.

In addition, according to the water treatment method according to the present embodiment, since biological treatment is adopted for the treatment of the separated liquid obtained by solid-liquid separation, the amount of phosphorus necessary for the growth of microorganisms in the biological treatment tank is By supplying, the water quality of the treated water by biological treatment can be kept higher and stabilized.

Generally, in biological treatment, about 1 mg/L of phosphorus is required for BOD of 100 mg/L. Therefore, it is desirable to supply phosphorus to the BOD of the influent (separated liquid) so as to satisfy this ratio. If the treatment is good, the concentration of phosphorus may be reduced to 1 mg/L or less, preferably 0.7 mg/L or less, more preferably 0.5 mg/L or less.

In particular, when iron-based or aluminum-based flocculants are used in the dehydration process of septic tank sludge and night soil sludge, phosphorus is taken into the sludge and the concentration of phosphorus contained in the dewatered separation liquid decreases, so phosphorus is added. As a result, treated water with more stable quality can be obtained. In rough processing, the supply of nutrients such as phosphorus tends to be neglected. This is because it is important in many cases.

First to seventh embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings below, the same or similar parts are denoted by the same or similar reference numerals. It should be noted that the embodiments shown below are examples of devices and methods for embodying the technical idea of the present invention. It does not specify anything. Moreover, it is of course possible to combine each configuration described in each embodiment shown below with a water treatment apparatus according to another embodiment.

(First embodiment)
As shown in FIG. 1, the water treatment apparatus according to the first embodiment separates water to be treated containing at least one of septic tank sludge and night soil sludge into solid-liquid separation into separated sludge and separated liquid. A solid-liquid separation device 1 and a biological treatment tank for performing biological treatment on the separated liquid by any of a non-clogging biofilm method, that is, a trickling filter method, a fluid carrier method, a rotating disk method, or a fixed bed method. 2 and a dilution tank 3 for diluting the biologically treated water so as to meet the sewage disposal standards.

In the embodiment of the treatment (BOD removal type) that serves as a reference when the BOD in the biologically treated water determines the dilution ratio, a dehydrator is provided as the solid-liquid separator 1, and a trickling filter is provided as the biological treatment tank 2. is preferred. Treatment conditions for the trickling filter include, for example, a BOD volume load of 0.5 to 7.5 kg-BOD/m ³ /d, and in still another embodiment, 1.0 to 5.0 kg-BOD/m ³ /d. can do.

The water to be treated is solid-liquid separated by the solid-liquid separator 1 to obtain a separated liquid and separated sludge having a BOD of, for example, 600 to 10000 mg/L, more typically 1000 to 5000 mg/L. The separated liquid is then introduced into the biological treatment tank 2 and BOD is roughly removed to obtain biologically treated water having a BOD of about 600 to 3000 mg/L. The biologically treated water is mixed with dilution water in the dilution tank 3, diluted to satisfy the sewage disposal standards, and then discharged into the sewage system. As the biological treatment tank 2, instead of the trickling filter bed, a fluid carrier tank, a contact oxidation tank, or a rotating disc apparatus can be used.

According to the water treatment apparatus and the water treatment method according to the first embodiment, the trickling filter bed, the fluidized carrier tank, the contact oxidation tank, and the rotating disk conventionally used as the septic tank sludge and night soil sludge biological treatment tank 2 By diluting biologically treated water that has been biologically treated using a device, etc., it is possible to omit power for aeration compared to treatment by the activated sludge method, etc., and sewage with simpler equipment in terms of equipment. Treated water for discharge can be obtained efficiently.

(Second embodiment)
The water treatment apparatus according to the second embodiment includes a film-like carrier 20 (FIGS. 2 and 3) are arranged.

As shown in FIG. 2, the membrane-like carrier 20 includes a support 21 and a membrane 22 supported by the support 21, the membrane 22 has a loop shape covering the support 21, and the separation liquid has a loop shape. and oxygen permeates from the space 23 formed on the inner surface of the loop-shaped membrane 22 to the outer surface of the membrane. The membrane 22 has a curved portion 22a that curves outside the support 21, and extension portions 22b and 22c that extend substantially parallel to each other from both ends of the curved portion 22a. An opening 22 d is formed on the side facing the bottom surface of the tank 2 for discharging sludge (not shown) deposited on the inner surface of the membrane 22 and then peeled off to the outside of the space 23 .

The film-like carrier 20 having the structure shown in FIGS. 2 and 3 is housed in a trickling filter bed as the biological treatment tank 2, so that BOD is not present outside the membrane 22 of the film-like carrier 20 on the separated liquid supply side. The oxygen-supplying side inside the membrane 22 will be a BOD-poor and oxygen-rich area, while the oxygen-rich area will be an oxygen-poor area. Therefore, it is possible to create conditions suitable for the nitrification reaction on the oxygen supply side while creating conditions suitable for the progress of the denitrification reaction on the supply side of the separated liquid.

According to the water treatment apparatus and the water treatment method according to the second embodiment, by using the film-like carrier 20 having the structure shown in FIGS. , an oxygen-poor area and an oxygen-rich area can be reliably formed within a certain region. Therefore, an environment can be created in which the nitrification-denitrification reaction proceeds more easily than when a filter medium such as sand or stone is used. Moreover, since the sludge deposited on the inner surface of the membrane 22 can be discharged from the opening 22d, stable treatment can be performed for a longer period of time. Many of the discharged sludge are separated from living organisms, and since these sludge have good sedimentation properties, it is preferable to supply solid-liquid separated water to the dilution tank via a solid-liquid separation device such as a sedimentation tank. The separated sludge should be returned to the receiving tank in front of the dehydration equipment for septic tank sludge and night soil sludge, dehydrated, and discharged outside as a dehydrated cake.

(Third Embodiment)
As shown in FIG. 4, the water treatment apparatus according to the third embodiment includes a biological treatment tank 2 (high-load biological treatment tank) 2a for removing BOD in the separated liquid, It includes parallel connection with a biological treatment tank (low-load biological treatment tank) 2b for removing nitrogen in the liquid.

The BOD load condition of the biological treatment tank 2a is not limited to the following, but is, for example, 3.0 to 10.0 kg-BOD/m ³ /d, and 3.0 to 8.0 kg- in other embodiments. BOD/m ³ /d, and in still another embodiment, 3.0 to 5.0 kg-BOD/m ³ /d. In the biological treatment tank 2a, treatment is performed for the purpose of roughly removing BOD in the separated liquid.

As for the BOD load condition of the biological treatment tank 2b, it is desirable to operate at a lower load than the biological treatment tank 2a ^. d, and in another embodiment, 0.5 to 1.5 kg-BOD/m ³ /d, and in still another embodiment, 0.5 to 1.0 kg-BOD/m ³ /d. . In the biological treatment tank 2b, treatment is performed for the purpose of removing TN (total nitrogen) in the separated liquid.

The inflow ratio of the separated liquid into the biological treatment tank 2a and the biological treatment tank 2b can be adjusted by the water quality (BOD, TN) of the separated liquid. Although not shown, control means may be provided for controlling the inflow ratio of the separated liquids to the biological treatment tanks 2a and 2b based on the quality of the separated liquids. In addition, although FIG. 4 shows an example in which two biological treatment tanks 2a and 2b are connected in parallel as the biological treatment tank 2, two or more biological treatment tanks may be provided. Of course.

According to the water treatment apparatus and the water treatment method according to the third embodiment, more appropriate treatment can be performed using a plurality of biological treatment tanks 2 according to the purpose of removing organic matter in the separated liquid. , more efficiently produce treated water that meets sewage rejection standards.

(Fourth embodiment)
As shown in FIG. 5, the water treatment apparatus according to the fourth embodiment includes a biological treatment tank 2 (high-load biological treatment tank) 2a for removing BOD in the separated liquid, It includes connecting in series with a biological treatment tank (low load biological treatment tank) 2b for removing nitrogen in the liquid. The biologically treated water finally obtained by the treatment in the biological treatment tanks 2a, 2b is circulated through the return means 4 to the front stage of the biological treatment tanks 2a, 2b.

According to the water treatment apparatus and the water treatment method according to the fourth embodiment, the BOD can be removed in the biological treatment tank 2a at the front stage, and the nitrification reaction can proceed in the biological treatment tank 2b at the rear stage. By using 4 to return the biologically treated water, circulation-type nitrification and denitrification can be further promoted, so that more stable water treatment for sewage discharge can be performed.

(Fifth embodiment)
As shown in FIG. 6, the water treatment apparatus according to the fifth embodiment includes two or more stages of biological treatment tanks 2a, 2b, . . . 2n connected in series. , . . . , and 2n.

The amount of inflow (step ratio) to each biological treatment tank 2a, 2b, . -BOD/m ³ /d, preferably 1.5 to 3.0 kg-BOD/m ³ /d, TN volume load of 0.5 to 2.0 kg-N/m ³ /d, preferably 0.7 to It is desirable to include one or ^more biological treatment tanks 2a, 2b, .

The flow rate of the water to be treated is 12 m ³ /d, the BOD is 2000 mg/L, and the NH ₄ --N is ⁷⁰⁰ mg/L. Table 1 shows an example of BOD and TN treated water quality when the step inflow amount of the separated liquid supplied from the inflow means 5 is changed. Cases A to C in Table 1 show the best treated water quality as ◎, the second best treated water quality as ○, and the third best treated water quality as △.

As shown in Table 1, when the step flow rate to the front stage is low as in Case A, the TN processing performance improves, and when the step flow rate to the front stage is high as in Case C, BOD processing performance tends to improve. This is because adjusting the load so that nitrification can proceed on the upstream side, where the amount of treated water can be reduced, contributes to nitrogen removal in the entire process.

According to the water treatment apparatus according to the fifth embodiment, the inflow means 5 can adjust the distribution ratio of the amount of water flowing into each of the biological treatment tanks 2a, 2b, . _, 2b _, . BOD and TN in the water to be treated can be efficiently removed by advancing the denitrification reaction with the BOD component contained in the liquid.

Moreover, according to the water treatment apparatus according to the fifth embodiment, unlike the circulation-type nitrification-denitrification method, the treated water is not circulated, so it is possible to reduce pump power compared to the circulation-type nitrification-denitrification method. becomes.

(Sixth embodiment)
The water treatment apparatus according to the sixth embodiment, as shown in FIG. A control means 6 is provided for controlling the step ratio of the separated liquid flowing into the tanks 2a, 2b, . . . 2n.

The step ratio of the separated liquid by the inflow means 5 is the volume load of each biological treatment tank 2a, 2b, ... 2n and the separated liquid obtained from the solid-liquid separation device 1 or from the biological treatment tank 2a, 2b, ... 2n Control means 6 shown in FIG. 7 can control the treatment in each of the biological treatment tanks 2a, 2b, .

For example, the control means 6 includes a measuring means 11 for measuring the water quality of the separated liquid obtained by the solid-liquid separator 1, and the biologically treated water obtained by each of the biological treatment tanks 2a, 2b, . . . 2n. Monitoring means 7 for monitoring the measurement results of the measuring means 12, 13, 14 are provided, and based on the monitoring results of the monitoring means 7, the control means 6 controls the volume load of each biological treatment tank 2a, 2b, ... 2n Accordingly, the step ratio of the separated liquid flowing from the inflow means 5 into each of the biological treatment tanks 2a, 2b, . . .

Items monitored by the monitoring means 7 are not particularly limited, but for example, flow rate, water temperature, pH, ORP, BOD, COD, TOC, ammonium nitrogen, nitrate nitrogen, etc. can be monitored. The location monitored by the monitoring means 7 is not limited to the example of FIG. 7, and it is also possible to pick up and monitor any of the typical biological treatment tanks 2a, 2b, . . . 2n.

The control means 6 is provided with a calculation means (not shown) for calculating the step ratio of the separated liquid flowing into each of 2a, 2b, . . . 2n based on the items monitored by the monitoring means 7, and Based on the above, the flow rate of the separation liquid flowing in from the inflow means 5 is adjusted by the flow rate adjusting device. A solenoid valve, a manual valve, etc. are mentioned as a flow control device.

According to the water treatment apparatus according to the sixth embodiment, the quality of the separated liquid obtained from the solid-liquid separator 1 or the biologically treated water obtained from the biological treatment tanks 2a, 2b, . Therefore, even if the water quality of the water to be treated fluctuates, the step ratio of the separated liquid can be set so that more appropriate biological treatment is performed in each of the biological treatment tanks 2a, 2b, . . . 2n. This allows for more stable processing.

(Seventh embodiment)
In the water treatment apparatus according to the seventh embodiment, as shown in FIG. 8, a biological treatment tank 2a and a biological treatment tank 2b are connected in parallel. The biological treatment tank 2a includes a trickling filter 201a for obtaining biologically treated water by aerobic decomposition of BOD and nitrification of ammonium nitrogen in the separated liquid, and a trickling filter for the biologically treated water obtained by the trickling filter 201a. A circulation line 203a for circulating through the bed 201a and a circulation tank 202a containing circulating water to be circulated through the trickling filter 201a are provided. The biological treatment tank 2b includes a trickling filter 201b for obtaining biologically treated water by aerobic decomposition of BOD and nitrification of ammonium nitrogen in the separated liquid, and a trickling filter for the biologically treated water obtained by the trickling filter 201b. A circulation line 203b for circulating through the bed 201b and a circulation tank 202b containing circulating water to be circulated through the trickling filter 201b are provided.

After solid-liquid separation of the water to be treated containing at least one of septic tank sludge and night soil sludge, the separated liquid is stored in the storage tank 2x and then supplied to the circulation tanks 202a and 202b of the biological treatment tanks 2a and 2b, respectively. be done. In the dehydration treatment of septic tank sludge and night soil sludge, when metal salts (polyiron, aluminum sulfate, etc.) are used as flocculating agents, phosphorus in the raw water is chemically fixed to iron and Al. goes down. For this reason, phosphorus supplying means 2y for supplying the necessary amount of phosphorus for the growth of microorganisms in the trickling filters 201a and 201b are connected to the upstream stages of the circulation tanks 202a and 202b, respectively. The form of phosphorus supplied from the phosphorus supplying means 2y is not particularly limited, but there are methods such as adding chemicals such as phosphoric acid and potassium dihydrogen phosphate, night soil sludge, and part of septic tank sludge. When using septic tank sludge and night soil sludge, the septic tank sludge and night soil sludge may be dispensed into the separated liquid storage tank after dehydration according to the insufficient amount of phosphorus.

As shown in FIG. 9, the circulation tank 202 can also be filled with a carrier. In this case, by housing the carrier with microorganisms attached to the surface in the 10 to 40% V/V circulation tank 202, the denitrification reaction proceeds by the microorganisms contained in the circulation tank 202. After the denitrification reaction progresses in the circulation tank 202 containing the carrier to which the microorganisms are adhered, the circulating water can be circulated to the trickling filter bed 201 and the treated water can be returned to the circulation tank 202 again.

According to the water treatment apparatus shown in FIG. 9, the carrier with microorganisms attached to its surface is accommodated in the circulation tank 202, so that the organic matter ( BOD) and nitrogen (TN) can be efficiently roughly removed.

According to the water treatment apparatus according to the seventh embodiment, sludge concentration control by return etc. is unnecessary, and troubles such as re-floating of sludge do not occur, with easy maintenance and management, organic matter contained in the separated liquid ( BOD) and nitrogen (TN) can be efficiently removed, which reduces the amount of dilution water required to meet sewage disposal standards and reduces facility operating costs.

Examples of the present invention are presented below along with comparative examples, which are provided for a better understanding of the invention and its advantages and are not intended to be limiting of the invention.

As a separation liquid, a dehydration separation liquid from a night soil treatment facility was supplied to the water treatment apparatus shown in FIG. 8 to obtain treated water. A nutrient (monopotassium phosphate (KH ₂ PO ₄ )) was added to the dehydrated liquid. Table 2 shows the properties of typical dehydrated liquids during the experiment.

As a processing flow, one trickling filter 201a in FIG. was allowed to flow in. The set load of each tank was increased stepwise, and the treated water quality at each load was confirmed (see FIG. 10). The outer diameter dimensions of the trickling filter bed 201a and the trickling filter bed 201b were 0.05 mW×1.15 mD×2.42 mH, and the effective volume was 2 m ³ . As the filter beds of the trickling filter bed 201a and the trickling filter bed 201b, the membrane carriers shown in FIGS. 2 and 3 were used. The surface area of the membrane carrier was 246 m ² . During the experiment period, the sludge was not returned from the treatment tank and the amount of sludge was not controlled. Table 3 shows the experimental results.

Under high load conditions (3.0 to 10 kg-BOD/m ³ /d), although the TN removal rate is as low as 18% or less, the BOD removal rate is 38 to 62%, and rough removal of BOD is possible. showed that there is Under low load conditions (0.5 to 2.0 kg-BOD/m ³ /d), the BOD removal rate is as high as 80% or more, and the TN removal rate is also 30 to 70%. It was shown that rough removal of In addition, under any load conditions, troubles such as outflow of sludge and blockage due to clogging did not occur at all.

Table 4 shows the relationship between the load and the amount of nitrification obtained from the above experiment. The nitrification amount reached a maximum around 2.5 kg-BOD/m ³ /d. From this result, when aiming at nitrogen removal, the BOD load should be 1.5 to 6.0 kg-BOD/m ³ /d, further 1.5 to 4.0 kg-BOD/m ³ /d, and even more It was found that the nitrogen removal efficiency can be increased by operating under load conditions of 2.0 to 3.0 kg/m ³ /d.

Table 5 shows the calculated dilution factor obtained from the removal rate of each load when the sewage rejection standards are BOD 600 mg/L and TN 380 mg/L. In the case of no biological treatment, 3.8-fold dilution was required, but according to this example, it was found that the dilution ratio can be reduced to 1.0 to 1.7-fold. The calculation below assumes that the entire amount of the dehydrated filtrate is flowed into the biological treatment. It is self-evident that it can be reduced.

1 Solid-liquid separation device 2, 2a to 2n Biological treatment tank 3 Dilution tank 4 Return means 5 Inflow means 6 Control means 7 Monitoring means 11 to 14 Measurement means 20 Membrane carrier 20 Support 22 Membrane 23 Space 200, 201a, 201b Trickling filter bed 202, 202a, 202b Circulation tank 203, 203a, 203b Circulation line

Claims (8)

Solid-liquid separation of water to be treated containing at least one of septic tank sludge and night soil sludge to separate into separated sludge and separated liquid,
At least part of the separated liquid is subjected to biological treatment using a non-clogging biofilm method by a trickling filter method,
diluting the biologically treated water obtained from the biological treatment to meet sewage disposal standards;
The biological treatment comprises a membrane-like carrier having a structure in which the separation liquid and oxygen permeate facing each other across a membrane surface, comprising a support and a membrane supported by the support, wherein the membrane is the Having a loop shape covering the support, the separation liquid permeates from the outer surface of the membrane, the oxygen permeates from the space formed on the inner surface of the membrane to the outer surface of the membrane, and is peeled off from the inner surface of the membrane. Using a biological treatment tank provided with the membrane carrier in which the membrane has an opening for discharging the sludge to the outside of the space , the BOD volume load of 1.5 to 10.0 kg-BOD / m A water treatment method comprising the step of performing the biological treatment at ³ /d . Solid-liquid separation of water to be treated containing at least one of septic tank sludge and night soil sludge to separate into separated sludge and separated liquid,
At least part of the separated liquid is subjected to biological treatment using a non-clogging biofilm method by a trickling filter method,
Diluting the biologically treated water obtained by the biological treatment so as to meet sewage disposal standards
including
The biological treatment includes stepwise inflow of the separated liquid into a biological treatment tank directly connected in series in two or more stages,
The biological treatment comprises a membrane-like carrier having a structure in which the separation liquid and oxygen permeate facing each other across a membrane surface, comprising a support and a membrane supported by the support, wherein the membrane is the Having a loop shape covering the support, the separation liquid permeates from the outer surface of the membrane, the oxygen permeates from the space formed on the inner surface of the membrane to the outer surface of the membrane, and is peeled off from the inner surface of the membrane. a water treatment method, wherein the biological treatment is performed using a biological treatment tank provided with the membrane-like carrier in which an opening is formed in the membrane for discharging the sludge to the outside of the space. BOD volume load of at least one biological treatment tank is 1.0 to 4.0 kg-BOD/m ³ /d, the water treatment method according to claim 2. Solid-liquid separation of water to be treated containing at least one of septic tank sludge and night soil sludge to separate into separated sludge and separated liquid,
At least part of the separated liquid is subjected to biological treatment using a non-clogging biofilm method by a trickling filter method,
Diluting the biologically treated water obtained by the biological treatment so as to meet sewage disposal standards
including
The biological treatment includes connecting a high-load biological treatment tank and a low-load biological treatment tank having a lower BOD volume load than the high-load biological treatment tank in parallel for biological treatment,
The biological treatment comprises a membrane-like carrier having a structure in which the separation liquid and oxygen permeate facing each other across a membrane surface, comprising a support and a membrane supported by the support, wherein the membrane is the Having a loop shape covering the support, the separation liquid permeates from the outer surface of the membrane, the oxygen permeates from the space formed on the inner surface of the membrane to the outer surface of the membrane, and is peeled off from the inner surface of the membrane. a water treatment method, wherein the biological treatment is performed using a biological treatment tank provided with the membrane-like carrier in which an opening is formed in the membrane for discharging the sludge to the outside of the space. The BOD volume load of the high load biological treatment tank is 3.0 to 5.0 kg-BOD/m ³ /d, and the BOD volume load of the low-load biological treatment tank is 0.5 to 1.0 kg-BOD/m ³ /d, the water treatment method according to claim 4. a solid-liquid separation device for solid-liquid separating water to be treated containing at least one of septic tank sludge and night soil sludge into separated sludge and separated liquid;
a biological treatment tank for subjecting at least part of the separated liquid to biological treatment using a non-clogging biofilm method based on a trickling filter;
a dilution tank for diluting the biologically treated water obtained in the biological treatment so as to meet sewage disposal standards;
In the biological treatment tank, a film-like carrier having a structure in which the separated liquid and oxygen permeate facing each other across a membrane surface is arranged, and the film-like carrier is supported by a support and the support. wherein the membrane has a loop shape covering the support, the separated liquid permeates from the outer surface of the membrane, and the oxygen passes from the space formed on the inner surface of the membrane to the outer surface of the membrane. Using the film-like carrier having openings formed in the membrane for discharging sludge that permeates and separates from the inner surface of the membrane to the outside of the space, the BOD volume load is 1.5 to 10.0 kg. - A water treatment device, characterized in that it is adjusted to the said biological treatment at BOD/m ³ /d. a solid-liquid separation device for solid-liquid separating water to be treated containing at least one of septic tank sludge and night soil sludge into separated sludge and separated liquid;
a biological treatment tank directly connected in series in two or more stages, in which at least part of the separated liquid is subjected to biological treatment using a non-clogging biofilm method based on a trickling filter;
a dilution tank for diluting the biologically treated water obtained by the biological treatment so as to meet sewage disposal standards;
an inflow means for stepwise inflow of the separated liquid into each of the biological treatment tanks directly connected in series;
a control means for controlling the step ratio of the separated liquid flowing into the biological treatment tank based on the volumetric load of the biological treatment tank and the quality of the separated liquid or the biologically treated water ;
In the biological treatment tank, a film-like carrier having a structure in which the separated liquid and oxygen permeate facing each other across a membrane surface is arranged, and the film-like carrier is supported by a support and the support. wherein the membrane has a loop shape covering the support, the separated liquid permeates from the outer surface of the membrane, and the oxygen passes from the space formed on the inner surface of the membrane to the outer surface of the membrane. A water treatment apparatus, wherein an opening is formed in said membrane for discharging sludge that permeates and separates from said inner surface of said membrane to the outside of said space. a solid-liquid separation device for solid-liquid separating water to be treated containing at least one of septic tank sludge and night soil sludge into separated sludge and separated liquid;
a biological treatment tank for subjecting at least part of the separated liquid to biological treatment using a non-clogging biofilm method based on a trickling filter;
a dilution tank for diluting the biologically treated water obtained by the biological treatment so as to meet the sewage disposal standards;
with
In the biological treatment tank, a film-like carrier having a structure in which the separated liquid and oxygen permeate facing each other across a membrane surface is arranged, and the film-like carrier is supported by a support and the support. wherein the membrane has a loop shape covering the support, the separated liquid permeates from the outer surface of the membrane, and the oxygen passes from the space formed on the inner surface of the membrane to the outer surface of the membrane. an opening formed in the membrane for discharging sludge that permeates and detaches from the inner surface of the membrane out of the space;
The biological treatment tank is a first biological treatment tank, and a second biological treatment that is connected in parallel to the first biological treatment tank and performs biological treatment with a BOD volume load lower than that of the first biological treatment tank. A water treatment device comprising a tank.

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