JPH0435794A - Method and equipment for treating sewage by complete mixing system - Google Patents

Abstract

PURPOSE:To increase the efficiency of treatment of sewage and to reduce the size of equipment by mixing porous plastic foam supporting microorganisms for treating sewage with the sewage in a treating tank, treating the sewage and discharging only the resulting treated water contg. suspended solids from the tank. CONSTITUTION:Porous plastic foam 22 supporting microorganisms for treating sewage is completely mixed with sewage 23 whose volume is equal to or larger than that of the foam 22 by agitation in a treating tank 21 and the sewage 23 is treated with the microorganisms. The foam 22 is then separated from the resulting treated water contg. suspended solids and only the treated water is discharged from the tank 21. The efficiency of treatment of the sewage can be increased and the size of the title equipment can be reduced.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a complete system for efficiently treating sewage by completely mixing an aerobic or anaerobic microorganism-attached carrier and sewage containing organic sludge substances. The present invention relates to a mixed sewage treatment method and its treatment device.

(Prior art) Recently, the water in rivers, lakes, and marshes has been contaminated by wastewater such as industrial wastewater and domestic wastewater, and the destruction of nature has become a major problem. To deal with this, various wastewater treatment methods have been proposed. For example, a fluidized bed sewage treatment method using aerobic or anaerobic microorganisms is known (Japanese Patent Publication No. 5
9-18119, JP 62-34434, JP 61-268395, JP 62-74
492, JP-A-62-74493).

For example, in an aerobic fluidized bed sewage treatment method, as shown in FIG. The waste water 3 is treated with microorganisms by introducing air into the bottom of the treatment tank 1 through the aeration system W7 to fluidize the carrier 2, and the suspended solids in the waste water 3 are also filtered through the carrier 2. The treated water is discharged from the bottom of the treatment tank 1 through the discharge channel 4, stored in the storage tank 5, and then released to the outside of the system. However, when the inside of the treatment tank 1 becomes clogged with suspended solids, the pump 6 and the aeration device 7 Backwashing is performed to eliminate clogging with suspended solids, and the backwash water is discharged outside the system.

On the other hand, in the anaerobic fluidized bed sewage treatment method, as shown in FIG. 14 to flow into the bottom of the treatment tank 11 to fluidize the carrier 12, the wastewater 13 is treated by the microorganisms attached and propagated on the carrier 12, and the treated water is discharged from the upper part of the treatment tank 11 to the outside of the system through the discharge path 15, Suspended substances in the waste water 13 are periodically discharged from the bottom of the treatment tank 11 to the outside of the system through a discharge path 17.

(Problem to be solved by the invention) However, in the conventional fluidized bed sewage treatment method, a material with a high specific gravity such as sand is used as the carrier 2.12 in both aerobic and anaerobic systems, and this is fluidized. As a result, the fluidization power is large and a large capacity pump 6 is used.
．． 14.16 and with appropriate flow conditions,
The dead space in treatment tank 1.11 increased, and the wastewater treatment efficiency was not very high.

In addition, in conventional fluidized bed wastewater treatment methods, the treatment tank 1.11 has a solid-liquid separation function or a filtration function, and the treated water and suspended solids are separated or filtered in the treatment tank 1.11. Therefore, in the aerobic treatment method, if there are many suspended solids in the wastewater 3, the fluidized bed will become severely clogged, requiring frequent backwashing, and in the anaerobic treatment method, If there are many suspended solids in the sewage I3, they will stay in the treatment tank 11, and it will be necessary to pull them out as sludge from the bottom of the treatment tank 11 through the discharge channel 17. In this case, the carrier 12 will also flow out. It is necessary to re-add this, and in any case there is a problem that processing efficiency is poor and the size of the apparatus increases.

In view of these problems, it is an object of the present invention to provide a sewage treatment method and a treatment device that can improve sewage treatment efficiency and downsize the device.

Among the above-mentioned problems, the problem of dead space can be solved by forcibly stirring the carrier and wastewater to achieve a complete mixing state in which they are almost uniformly dispersed in each part of the treatment tank, but if the carrier and wastewater are completely mixed, A problem arises in that microorganisms that have adhered to and propagated on the carrier are peeled off from the carrier and carried away with the wastewater out of the treatment tank.

Regarding the problem of fluidization power, for example, JP-A-62
As shown in Japanese Patent No. 74493, this problem can be solved by using a carrier with a small specific gravity such as a sponge, synthetic resin fiber, or natural fiber, but this does not solve the problem of dead space.

(Means for Solving the Problems) As a result of intensive research to solve the above-mentioned problems, the inventor of the present invention found that if plastic foams such as urethane foams and PvC foams are used as microbial carriers,
The problems of dead space and fluidization power can be solved, and if only sewage purification treatment is performed using microorganisms in the treatment tank, there is no need for backwashing or sludge removal treatment mechanisms, making the equipment more compact. As well as being able to handle treated water and suspension @! The present invention was completed by focusing on the fact that even cleaner final treated water can be obtained by using a dedicated solid-liquid separation or filtration device.

In other words, the completely mixed sewage treatment method according to the present invention is characterized in that ``a porous plastic foam carrying sewage treatment microorganisms and sewage in a volume equal to or more than that of the foam are stirred into a treatment tank. The wastewater is treated by the microorganisms in a completely mixed state in each part, and the porous plastic foam is separated from the treated water mixed with suspended solids and held in a treatment tank, while only the treated water mixed with suspended solids is treated. The gist is that the water was discharged from the treatment tank.

Further, the aerobic complete mixing type sewage treatment equipment according to the present invention is constructed using a porous plastic foam having an apparent specific gravity of rO, 95 to 1.5, and a microbial carrier on which aerobic microorganisms adhere and propagate. , and the actual volume of the carrier and the tank capacity are in the range of 1 = 3 to 1:6, and the sewage volume in the treatment tank is maintained at an equal or higher volume to the carrier. a sewage supply system that causes sewage to flow into the upper part of the treatment tank; an aeration device that supplies air to the lower part of the treatment tank so that the microbial carrier and the sewage are stirred and completely mixed in each part of the treatment tank; A discharge system for discharging treated water mixed with suspended solids from the treatment tank, and a separator for separating the microbial carriers from the suspended solids mixed treated water and retaining them in the treatment tank.
The gist is that.

Further, the anaerobic complete mixing type sewage treatment apparatus according to the present invention is constructed using a porous plastic foam having an apparent specific gravity of RO, 95 to 1.5, and a microbial carrier on which anaerobic microorganisms adhere and propagate. a treatment tank which accommodates the carrier, and in which the actual volume of the carrier and the tank capacity are in the range of 1:3 to 1:6; A sewage supply system that flows sewage into the lower part of the treatment tank so that the microbial carrier and the sewage are stirred and completely mixed in each part of the treatment tank; and a separating body that separates the microbial carrier from the suspended solids mixed treated water and holds it in the treatment tank.
The gist is that.

Here, the plastic foam is, for example, urethane foam,
PVC foam, vinyl chloride foam, etc. can be used.

The conditions for a carrier that are good for the adhesion and propagation of microorganisms are the surface;
Furthermore, it is preferable that the material has a hydrophilic surface, and that the surface potential is positively charged. In addition, the carrier of the present invention places more emphasis on physical properties, and the carrier itself has a three-dimensional structure with a rough surface.In particular, because it has a three-dimensional structure, microorganisms attached to the carrier surface can be temporarily detached. Even if the carrier is heated, a large amount of microorganisms can be retained inside the tank, so there is no problem even if the tank is completely mixed.In addition, in the case of aerobic treatment, the surface of the carrier is aerobic for several millimeters, and the inside is anoxic. Although there is a possibility of this, it actually makes denitrification processing by internal anaerobic bacteria possible.

Further, for solid-liquid separation or filtration outside the treatment tank, gravity sedimentation separation, rapid filtration separation, pressure flotation separation, ultrafiltration separation, centrifugation, etc. can be used.

Further, the separator may be any material as long as it can separate the microorganism carrier and the treated water, and for example, a perforated plate, a net, a screen, etc. can be used.

Next, to explain the reasons for limiting the conditions, first, the apparent specific gravity of the plastic foam is 0. The reason for setting the value to 95 to 1.5 is to enable easy forcible stirring of the carrier and sewage with small mixing energy, allowing the use of a small-capacity pump, and also to reduce the volume of sewage between the microbial carrier and the sewage. The reason why the amount is equal or more is that some of the sewage is impregnated with the microbial carrier, and in order to keep the sewage and the carrier in a completely mixed state, a sufficient amount of sewage is required, that is, an amount equal to or more than the amount of the microbial carrier. This is because.

Further, according to the present invention, the plastic foam for supporting microorganisms has a cell count of 13 to 55 cells/inch, an apparent specific gravity of 0.95 to 1.5, and is suitable for supporting microorganisms for sewage treatment. I can donate my body.

(Function) In the present invention, since the inside of the treatment tank is in a completely mixed state, there is almost no dead space inside the treatment tank, and the microorganisms attached to the carrier and the sewage are reliably contacted and the sewage is efficiently treated. .

In addition, the treatment tank has only the function of purifying wastewater using microorganisms, and solid-liquid separation or filtration can be performed outside the treatment tank, so that the treated water does not contain a sufficient amount of suspended solids. As a result, conventional treatments such as backwashing and sludge extraction are no longer necessary, and this also improves sewage treatment efficiency, and allows treatment water that is sufficiently contaminated with suspended solids to be separated by gravity sedimentation. , rapid filtration separation method, pressure flotation separation method, ultrafiltration separation method, centrifugation method, etc., and can be separated into even clearer treated water and thickened sludge.

Furthermore, since the plastic foam is used as a microbial carrier, even if the carrier and wastewater are completely mixed, all the microorganisms will not be separated from the carrier, and a separator is provided to separate the microbial carrier from the treated water. Since it is separated and held in a treatment tank, continuous treatment of wastewater becomes possible.

(Example) Hereinafter, the present invention will be described in detail based on specific examples shown in the drawings.

FIG. 1 shows an aerobic complete mixing type sewage treatment apparatus according to a first embodiment of the present invention, in which aerobic microorganism carriers 22 are contained in a treatment tank 21 in an actual volume of 1/3 to 1/3 of the tank volume. 1
/6 filled, and the microorganism carrier 22 has a cell number of 13 to 55.
It is constructed using a porous plastic foam such as urethane foam or PC foam having an apparent specific gravity of 0.95 to 1.5 mm/inch.

Further, the treatment tank 21 is provided with a sewage supply system 24 that supplies sewage 23 from above.
4 supplies the waste water 23 so that the volume of the waste water 23 is maintained equal to or larger than that of the microorganism carriers 22.

Further, the treatment tank 21 is provided with an aeration device 25 that supplies air from the bottom of the tank, and the aeration device 25 forcibly agitates the microorganism carriers 22 and the waste water 23 by using the supplied air, and approximately A completely homogeneous and dispersed state of mixing is achieved.

Furthermore, the treatment tank 21 is provided with a discharge system 26 for discharging treated water mixed with suspended matter from the treatment tank 21,
A screen (separator) 27 is provided between the discharge system 26 and the treatment tank 21 to separate the microbial carriers 22 from the suspended matter mixed treated water and to retain the microbial carriers 22 in the treatment tank 21. .

Further, the downstream end of the discharge system 26 is connected to a flocculation tank 28, and the treated water from the flocculation tank 28 is transferred to a pressurized flotation separation tank 29.
is being sent to.

Next, the processing method will be explained.

When the wastewater 23 is supplied from the wastewater supply system 24 to the treatment tank 21, the wastewater 23 is treated in the treatment tank 21 by a large amount of microorganisms attached to the carrier 22.

At this time, in the treatment tank 21, the carriers 22 and the waste water 23 in the tank are kept in a completely mixed state by the air supplied from the aeration device 25, and the waste water 23 comes into sufficient contact with the microorganism carriers 22 and efficiently It is processed.

In addition, the treated water is discharged from the tank upper outflow pipe 26 and the carrier 2
2 also tries to flow out with the treated water, but microbial carrier 2
2 is separated from the treated water by a screen 27 and returned to the treatment tank 21, and only the treated water containing suspended matter is sent to the flocculation tank 21.
is discharged.

This treated water is subjected to a flocculation treatment in a flocculation tank 28 by adding a flocculant 30 and a neutralization side 31 thereto. A polymer flocculant 32 is further added to the coagulated treated water in a transfer line to increase the size of the coagulated flocs, which are then transferred to a pressurized flotation separation tank 29. The treated water is separated from flocs in the pressurized flotation separation tank 29, and the final treated water is discharged to the outside of the system through a discharge system 33 and the concentrated suspended solids are discharged to the outside of the system through a discharge system 34, respectively.

In the sewage treatment apparatus of this embodiment as described above, the inside of the tank 21 is maintained in a completely mixed state, so that almost no dead space is created in the tank 21, and the contact efficiency between the microorganism-attached carrier 22 and the sewage 23 is improved. can be improved, and sewage treatment efficiency can be increased.

In addition, in this sewage treatment device, the suspended solids contained in the sewage 23 are discharged from the treatment tank 21 together with the treated water, so even if there is a large amount of suspended solids contained in the sewage 23, the suspended solids are discharged into the treatment tank 21. There is no residue, and treatments such as backwashing and sludge extraction are not required, reducing management and power, and improving treatment efficiency.

Furthermore, in this sewage treatment equipment, the treated water containing suspended solids is treated with a system dedicated to solid-liquid separation, so the final treated water can be extremely clean, and the sludge can be taken out in a concentrated state. This makes it possible to easily process the sludge and downsize the microbial purification system (processing tank 21) for the wastewater 23.

In addition, in this sewage treatment equipment, the apparent specific gravity of the carrier 2 is
2, the energy for mixing and flow can be reduced, and the capacity of the pump can be reduced.

In addition, in this sewage treatment equipment, plastic foam is used as the microorganism carrier 22, so the treatment tank 21
Even in a completely mixed state, the amount of microorganisms retained is very high, allowing for highly efficient treatment.Also, since the carrier 21 is separated from the treated water by a screen and retained in the treatment tank 21, the amount of microorganisms retained is very high. Continuous processing becomes possible.

Further, FIG. 2 shows an aerobic complete mixing type sewage treatment apparatus according to a second embodiment of the present invention. This embodiment is the same as the first embodiment, except that a perforated plate 35 is used to separate the carrier, and an ultrafiltration separation device 36 is used to separate the suspended solids.

In other words, process! The interior of 21 is maintained in a completely mixed state by aeration from an aeration device 25, and when wastewater 23 flows into the treatment tank 21, it is treated by a large amount of microorganisms attached to the carrier 22 and discharged. 34 and remains in the treatment tank 21.

When the treated water containing suspended solids is discharged outside the treatment tank 21, it flows into the storage tank 28, where it is temporarily stored, and then is pumped to the ultrafiltration device 36 by the pump 37, and the concentrated suspension is discharged. The final treated water is discharged out of the system by the system 34 and the discharge system 33, thus obtaining clean final treated water.

Further, FIG. 3 shows an anaerobic complete mixing type sewage treatment apparatus according to a third embodiment of the present invention. In this embodiment, the treatment tank 41 is made airtight, and a screen 27 is used to separate carriers, and an ultrafiltration separation device 36 is used to separate suspended substances.

That is, in this device, when wastewater 23 flows into the treatment tank 41, it is treated by a large amount of microorganisms attached to the carrier 22, and inside the tank 21, the circulating water and wastewater are pumped from the lower part of the tank 41 by the circulation pump 43. A completely mixed state is maintained by introducing 23 into the mixture.

The carrier 22 is separated from the treated water by the screen 27 and remains in the treatment tank 41, and only the treated water containing suspended matter is discharged outside the tank and flows into the storage tank 28 where it is temporarily stored. 37 to an ultrafiltration device 36, the concentrated suspension is discharged by a discharge system 34, and the final treated water is discharged by a discharge system 33, thereby obtaining clean final treated water.

Back cover: The raw water contains BOD100, which mainly contains glucose and acetic acid.
Artificial wastewater with a pH of 6.5 and a pH of 6.5 was used as a treatment experimental apparatus as shown in FIG. 6, and a 10-/so urethane foam was used as a carrier.

At the start of the experiment, sewage sludge was used as the seed sludge, the microbial adhesion period was for one day, and the inflow of wastewater was started the next day.

The BOD load was set at a high level of 5 kg/rrf·day from the time the wastewater was introduced, and the BOD removal rate after 2 days was good at around 60%. From around the 4th day, the removal rate improved dramatically, so the BOD load was reduced to 6 kg/n?・The removal rate on the 7th day was 95%.

After that, continuous operation was performed at a BOD load of 6 kg/% per day, and after one month, a removal rate of around 98-99% was secured, and even after six months of operation, there was no damage to the carrier, and no decrease in processing capacity was observed. I couldn't.

Usually, the BOD load is 0.5-1゜0kg/by activated sludge method.
2.0kg/day using the rotating disk method, 3.0kg/day using the fluidized bed method
．． 5 to 4.0 kg/nf·day, whereas the final method achieved sufficient processing capacity even with a BOD load of 6.0 kg/nf·day.

In addition, in this example, when the volume of the foamed carrier is 1011/II', 450 pieces occupy a filling volume of 0.92 (the volume of the upper body of the carrier is 0.45ε), and the total volume of the processing tank is 1.6ffi.
And so. From this, the volume of the foamed carrier stop valve:total volume of the processing tank is preferably about 1:3 to 1:6, and the volume ratio in this example (1:1) is preferable.
:3.5), the inside of the tank can be maintained in a completely mixed state, and the above-mentioned sewage treatment ability can be exhibited.

In addition, the smaller the size of the carrier, the larger the surface area, but since it is necessary to allow separation using a screen etc. and the outflow of suspended substances, 2 to 20 particles/-1 and preferably 3 to 15 particles are required. /- is better.

Further, the shape may be either angular or spherical, but spherical is preferable.

Further, in this example, the carrier density is 0.057 g/cd, the specific gravity is about 1.2 to 1.5, and since it is continuous foaming, it has a three-dimensional structure.

1 fruit] 4 As a microorganism carrier, density 0.121g/ej and IO■/l
The process was the same as in the previous example, except that PVC foam of 1'' was used. The BOD load was set to a high load of 5 kg/nf·day, and the BOD removal rate after 2 days was good at around 60%. The BOD load was 6 kg/%/day, and the removal rate on the 7th day was 97%. After that, BOD load 6kg/
Continuous operation on rd day and 98 to 9 after one month.
A removal rate of around 9% was obtained, and even after 6 months of operation, there was no damage to any of the carriers, and there was no decrease in processing capacity.

(Effects of the Invention) As described above, according to the completely mixed sewage treatment method and its treatment device according to the present invention, a porous plastic foam supporting microorganisms and a volume equal to or more than the foam The sewage is stirred and mixed completely in each part of the treatment tank, and the sewage is treated by the microorganisms, and the porous plastic foam is separated from the treated water mixed with suspended solids and held in the treatment tank. Since only the suspended solid mixed treated water is discharged from the treatment tank, it is possible to improve wastewater treatment efficiency and to downsize the apparatus.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an aerobic complete mixing type sewage treatment device according to a first embodiment of the present invention, and FIG. 2 is a schematic configuration diagram showing an aerobic complete mixing type sewage treatment device according to a second embodiment of the present invention. 3 is a schematic configuration diagram showing an anaerobic fully mixed sewage treatment apparatus according to a third embodiment of the present invention, and FIGS. 4 and 5 are conventional aerobic and anaerobic fluidized bed sewage treatment systems, respectively. A schematic configuration diagram showing the apparatus, and FIG. 6 is a diagram for explaining the present invention in detail. 21.41... treatment tank, 22... plastic foam, 23... sewage, 24-... sewage supply system, 2 aeration device, 26 discharge system, 27.35 ...separated body.

Claims (5)

[Claims] (1) A porous plastic foam supporting microorganisms for sewage treatment and sewage with a volume equal to or greater than that of the foam are stirred, and the sewage is completely mixed in each part of the treatment tank, and the sewage is treated by the microorganisms. The porous plastic foam is separated from the treated water mixed with suspended solids and held in the treatment tank, while only the treated water mixed with the suspended solids is discharged from the treatment tank. Completely mixed sewage treatment method. (2) The suspended solids mixed treated water is separated from the suspended solids by gravity sedimentation separation method, rapid filtration separation method, pressure flotation separation method, ultrafiltration separation method, or centrifugal separation method outside the treatment tank. 2. The completely mixed wastewater treatment method according to claim 1, wherein the wastewater treatment method is separated into two parts. (3) A plastic foam supporting microorganisms for sewage treatment, which has a cell count of 13 to 55 cells/inch and an apparent specific gravity of 0.95 to 1.5. foam. (4) Constructed using a porous plastic foam having an apparent specific gravity of 0.95 to 1.5, it houses a microbial carrier on which aerobic microorganisms adhere and propagate, and the actual volume of the carrier and tank capacity are 1: a treatment tank having a ratio of 3 to 1:6; a sewage supply system that causes sewage to flow into the upper part of the treatment tank so that the volume of sewage in the treatment tank is maintained equal to or more than the amount of the carrier; an aeration device that supplies air to the lower part of the treatment tank so that the microbial carriers and wastewater are stirred and completely mixed in each part of the treatment tank; and an aeration device that discharges treated water mixed with suspended matter from the treatment tank. An aerobic complete mixing type sewage treatment device comprising: a discharge system; and a separator that separates the microbial carrier from the suspended solids mixed treated water and holds it in the treatment tank. (5) Constructed using a porous plastic foam having an apparent specific gravity of 0.95 to 1.5, containing a microbial carrier on which anaerobic microorganisms adhere and propagate, the actual volume of the carrier and tank capacity being 1 :3 to 1:6, and the volume of sewage in the treatment tank is maintained at an equal or higher volume to the carrier, and the microorganism carrier and wastewater are agitated in each part of the treatment tank. a sewage supply system that flows sewage into the lower part of the treatment tank so that the sewage is in a completely mixed state; a discharge system that discharges the treated water mixed with suspended solids from the treatment tank; An anaerobic complete mixing type sewage treatment device comprising: a separator that separates the water from the treated water and holds it in the treatment tank.