JP2000288587A - Method and apparatus for treating excretion sewage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the quality of treated water while reducing cost of membrane washing by performing ozone injection treatment between a sedimentation separation tank and the circulating tank or membrane supply tank to a membrane filter apparatus of a rear stage. SOLUTION: Excretion sewage is circulated between a denitrification tank 2 and a nitrification tank 3 to be subjected to anaerobic nitrification and denitrification treatment and the treated liquid is subjected to solid-liquid separation treatment in a membrane filter apparatus 4 and the obtained biologically treated water 5 is transferred to a flocculation tank 7. An inorg. flocculant 6 is added to the biologically treated water 5 in the flocculation tank 7 to flocculate an SS component containing phosphate ions and COD and the formed flocs are separated into sedimented sludge and a supernatant liquid in a sedimentation separation tank 8 and the sedimented sludge is transferred to a sludge treatment process and dehydrated to be incinerated. Ozone 9 is directly injected in the supernatant liquid from an ozone generator 10 through an in-line and ozone dissolved water to be treated is sent into a circulating tank 11 and supplied to a membrane filter apparatus 14 from the circulating tank 11 to be subjected to solid-liquid separation treatment. Filtered water 15 is transferred to an activated carbon adsorbing tower 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating human wastewater, such as human waste, septic tank sludge, leachate from a landfill, and mixtures thereof, and relates to a hardly decomposable C.
The present invention relates to a method and apparatus for treating human wastewater suitable for removing OD components, chromaticity components, and the like.

[0002]

2. Description of the Related Art In recent years, a technique called a membrane separation type high-load denitrification treatment method (for example, Japanese Examined Patent Publication No. 63-28000) may be used as a method for treating human wastewater such as human waste or septic tank sludge. FIG. 7 shows a general processing flow in a conventional membrane separation type high load denitrification processing process. The processing flow will be described with reference to FIG.

[0003] The treatment apparatus for human wastewater shown in FIG. 7 is a biological nitrification and denitrification treatment apparatus comprising a denitrification tank 2 and a nitrification tank 3, a membrane filtration apparatus 4, a coagulation tank 7, a sedimentation separation tank 8, and a circulation tank 11. , A membrane filtration device 14 and an activated carbon adsorption tower 17. First, the human wastewater 1 flows into the denitrification tank 2 undiluted or diluted at an appropriate dilution ratio, and circulates between the denitrification tank 2 and the nitrification tank 3 to be anaerobically denitrified. It is treated with nitrogen. The wastewater subjected to the nitrification and denitrification treatment is subjected to solid-liquid separation by the membrane filtration device 4, and the biologically treated water 5 that has passed through the membrane filtration device 4 is transferred to the coagulation tank 7. Coagulation tank 7
In the method, an inorganic coagulant 6 such as aluminum sulfate, ferric chloride, or polyiron is added to the biologically treated water 5 to coagulate the SS containing phosphate ions and COD. The flocculated floc is separated into settled sludge and supernatant in the settling tank 8, and the supernatant is transferred to the circulation tank 11. On the other hand, the settled sludge is transferred to a sludge treatment step, and is incinerated after dehydration treatment. The supernatant liquid transferred to the circulation tank 11 is supplied from the circulation tank 11 to the membrane filtration device 14 to be separated into a solid and a liquid. The membrane filtered water 15 obtained here is transferred to an activated carbon adsorption tower 17 filled with activated carbon to adsorb and remove the COD component and the chromaticity component. The treated water is discharged out of the system as discharge water 18.

[0004]

The above-mentioned conventional membrane separation type high-load denitrification process has the following problems.

[0005] Since a large amount of organic substances such as a hardly decomposable COD component and a chromaticity component remain in the sewage supplied to the membrane filtration device 14, the membrane derived from the organic material in the membrane filtration device 14. Fouling phenomenon is observed, and there is a drawback that clogging occurs in a relatively short time. Further, it is necessary to frequently carry out chemical cleaning with an acid or an alkali in order to eliminate the clogging. Therefore, there is a problem that the cost and labor for the chemical cleaning operation are increased, leading to an increase in cost.

If the COD of the effluent water obtained by treatment in the activated carbon adsorption tower 17 exceeds the effluent water quality standard, which is usually 10 to 15 mg / L or less, the activated carbon must be regenerated and the frequency of regeneration is reduced. In many cases, maintenance is complicated and the processing cost is expensive.

The present invention has been completed as a result of intensive studies to overcome the above-mentioned problems, and by using ozone efficiently, the quality of treated water can be increased and the cost of membrane cleaning can be increased. It is an object of the present invention to provide a method for treating human wastewater and a treatment apparatus to which the method can be applied efficiently.

[0008]

According to the present invention, after biologically treating human wastewater, a solid-liquid separation treatment is performed using a membrane filtration device, and a coagulant is added to the permeate from the membrane filtration device. After the addition, sedimentation is performed in a sedimentation separation tank, and solid-liquid separation treatment is performed by another membrane filtration device. In a method for treating human wastewater, a circulation tank or membrane supply to the sedimentation separation tank and a subsequent membrane filtration device is performed. This is a method for treating human wastewater, wherein an ozone injection process is performed in the middle of a tank.

In the present invention, an ozone contact tank is further provided after the latter membrane filtration device, and filtered water from the second membrane filtration device is supplied to the ozone contact tank, and the ozone contact tank is supplied to the ozone contact tank. A method for treating human wastewater, which comprises re-injecting ozone for treatment.

[0010] The present invention is also a method for treating human wastewater, wherein the membrane used in the former membrane filtration device and the latter membrane filtration device is a microfiltration membrane or an ultrafiltration membrane.

Further, the present invention provides an ozone detector installed at a membrane filtration outlet of a subsequent membrane filtration device so that the residual ozone concentration in the membrane filtration water falls within a range of 0.01 to 10 mg / L. This is a method for treating human wastewater, which comprises adjusting an ozone injection amount.

Further, in the present invention, the ozone injection amount may be adjusted by continuously measuring the residual ozone concentration of the membrane filtration water by an ozone detector installed at a membrane filtration outlet of a subsequent membrane filtration device. The residual ozone concentration in water is 0.01 to 10
and performing feedback control of the ozone injection amount based on the measured value of the residual ozone concentration so as to be within the range of mg / L to adjust the residual ozone concentration within the range. Processing method.

Further, the present invention is characterized in that ozone is directly injected in-line into a pipe connecting the sedimentation separation tank with a circulation tank or a membrane supply tank to a subsequent membrane filtration device, and the treatment of human wastewater Is the way.

Further, the present invention is a method for treating human wastewater, which comprises injecting ozone into a circulation tank or a membrane supply tank to a subsequent membrane filtration device.

Furthermore, the present invention provides an ozone dissolving tank installed between the sedimentation separation tank and a circulating tank or a membrane supply tank for a subsequent membrane filtration device, and injecting ozone into the ozone dissolving tank. This is a method for treating human wastewater.

Further, the present invention provides a method for treating human wastewater biologically, and then performing a solid-liquid separation treatment using a membrane filtration device.
After adding a flocculant to the permeate from the membrane filtration device, sedimentation is performed in a sedimentation separation tank, and solid-liquid separation treatment is performed by another membrane filtration device. Ozone injection equipment that injects ozone between the tank and the circulation tank or membrane supply tank to the membrane filtration membrane device at the subsequent stage, and measures the residual ozone concentration in the membrane filtration water installed at the membrane filtration outlet of the membrane filtration device at the later stage Ozone detector to measure the residual ozone concentration in the membrane filtered water by the ozone detector, and based on the measured value, operate the ozone injection equipment to adjust the ozone injection amount, and to measure the residual ozone concentration in the membrane filtered water. A control device for controlling an ozone concentration to be within a predetermined range is provided.

Further, the present invention is characterized in that, in order to further ozone-treat the filtered water from the latter-stage membrane filtration device, an ozone contact tank is further provided after the latter-stage membrane filtration device. Processing device.

Further, the present invention is an apparatus for treating human wastewater, wherein the first-stage membrane filtration device and the second-stage membrane filtration device are a microfiltration membrane device or an ultrafiltration membrane device.

Further, the present invention is characterized in that ozone is directly inline-injected into a pipe connecting the sedimentation separation tank and a circulation tank or a membrane supply tank of a subsequent membrane filtration device, wherein the sewage wastewater is characterized in that ozone is directly injected. Processing device.

Further, the present invention is an apparatus for treating human wastewater, characterized in that ozone is injected into a circulation tank or a membrane supply tank to a subsequent membrane filtration apparatus.

Further, the present invention provides an ozone dissolving tank installed between the sedimentation separation tank and a circulating tank or a membrane supply tank for a subsequent membrane filtration device so that ozone is injected into the ozone dissolving tank. An apparatus for treating human wastewater, characterized in that:

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a human wastewater treatment apparatus according to the present invention.

As shown in FIG. 1, a method and an apparatus for treating human wastewater based on the present invention include a biological nitrification denitrification treatment apparatus comprising a denitrification tank 2 and a nitrification tank 3, a membrane filtration apparatus 4, Tank 7, sedimentation separation tank 8, circulation tank 11, membrane filtration device 14, ozone generator 10, exhaust ozone gas treatment equipment 13,
It comprises an ozone detector 16 and an activated carbon adsorption tower 17. First, the human wastewater 1 flows into the denitrification tank 2 undiluted or diluted at an appropriate dilution ratio, and circulates between the denitrification tank 2 and the nitrification tank 3 to be anaerobically denitrified. It is treated with nitrogen. The sewage subjected to the nitrification and denitrification treatment is subjected to solid-liquid separation by a membrane filtration device 4, and the biologically treated water 5 that has passed through the membrane filtration device 4 is transferred to a coagulation tank 7. In the coagulation tank 7, an inorganic coagulant 6 such as aluminum sulfate, ferric chloride, or polyiron is added to the biological treatment water 5 to coagulate SS containing phosphate ions and COD. The flocculated floc is separated into a settled sludge and a supernatant in the settling tank 8, and the settled sludge is transferred to a sludge treatment step, and is incinerated after dehydration treatment. On the other hand, ozone 9 is directly injected in-line from the ozone generator 10 into the supernatant, and the water to be treated in which ozone is dissolved is sent to the circulation tank 11. The water to be treated in which the ozone is dissolved is supplied from the circulation tank 11 to the membrane filtration device 14, where it is separated into solid and liquid. The filtered water 15 that has passed through the membrane filtration device 14 is transferred to an activated carbon adsorption tower 17 filled with activated carbon, and contaminants are removed by adsorption. Thereafter, the treated water from which the contaminants have been adsorbed and removed is discharged out of the system as discharge water 18.

In the process in which the membrane filtered water 15 is fed into the activated carbon adsorption tower 17, the concentration of residual ozone in the membrane filtered water is detected by the ozone detector 16. The supply amount of ozone from the ozone generator 10 is controlled based on the measured value of the ozone concentration. Further, the exhausted ozone gas 12 discharged from the circulation tank 11 is processed by the exhausted ozone gas processing equipment 13. The circulating water from the membrane filtration device 14 is returned to the circulation tank 11 through a circulation line. Further, the same applies to the following embodiments, but the ozone detector 16 may be a dissolved ozone concentration detector.

In this embodiment, the concentration of residual ozone in the membrane filtered water is constantly measured by the ozone detector 16, and the ozone generation is controlled so that the residual ozone concentration is in the range of 0.01 to 10 mg / L. The amount of ozone injected directly in-line from the device 10 is adjusted by the applied voltage of the ozone generator, the opening and closing operation of the valve, and the like. For example, C
The residual ozone concentration in the membrane filtration water is calculated by a control means such as a PU (central processing unit), and the amount of ozone injected in-line is feedback-controlled.

Another example of the human wastewater treatment apparatus according to the present invention is shown in FIG.

As shown in FIG. 2, in this embodiment,
Ozone 9 from the ozone generator 10 is not injected into the water to be treated fed into the circulation tank 11,
And an ozone oxidation reaction is performed in the circulation tank 11. Otherwise, it is the same as the embodiment of FIG.

Another example of the human wastewater treatment apparatus according to the present invention is shown in FIG.

In the embodiment of FIG. 3, the sedimentation separation tank 8
An ozone dissolving tank 19 is provided between the tank and the circulation tank 11, and ozone 9 from the ozone generator 10 is injected into the ozone dissolving tank 19. Otherwise, it is the same as the embodiment shown in FIG. That is, after performing the steps up to the sedimentation tank 8 in the same manner as described in FIG. 1, the supernatant from the sedimentation tank 8 is supplied to the ozone dissolution tank 19. In addition, ozone 9 is injected into the ozone dissolving tank 19 from the ozone generator 10, and the water to be treated in which ozone is dissolved is sent to the circulation tank 11. The circulation tank 11 supplies the treated water in which ozone is dissolved to the membrane filtration device 14. The membrane filtered water 15 that has passed through the membrane filtration device 14 is transferred to an activated carbon adsorption tower 17 filled with activated carbon, and the treated water that has been treated is discharged out of the system as discharge water 18. In the process where the membrane filtered water 15 is sent to the activated carbon adsorption tower 17, the residual ozone concentration in the membrane filtered water is detected by the ozone detector 16, and based on the measured value of the ozone concentration,
The amount of ozone supplied from the ozone generator 10 to the ozone dissolving tank 19 is controlled. Further, the exhausted ozone gas 20 discharged from the ozone dissolving tank 19 and the exhausted ozone gas 12 discharged from the circulation tank 11 are processed by an exhausted ozone gas treatment facility 13. The circulating water from the membrane filtration device 14 is returned to the circulation tank 11 through a circulation line.

Next, the ozone dissolving tank 19 of the present invention will be described. The purpose of the ozone dissolving tank 19 is to dissolve ozone in the membrane supply water in order to keep the filtration speed of the membrane filtration device 14 high. Ozone generator 10
The ozone 9 is injected into the ozone dissolving tank 19 from above, and the amount of residual ozone remaining in the membrane filtration water 15 obtained by the membrane filtration device 14 is 0.01 to 0.01 to maintain the filtration speed of the membrane filtration device 14 high. 10 mg / L, desirably 0.1
It is good to be 3 mg / L. If the residual ozone concentration in the membrane filtration water is higher than 10 mg / L, even if an ozone-resistant membrane material is used as the filtration membrane of the membrane filtration device 14, there is a possibility that membrane degradation will occur due to reaction with ozone in the long term. There is
Considering the replacement time of the membrane module, 10mg /
Up to L is allowed. The residual ozone concentration is 10 mg
If it exceeds / L, there is a problem that the amount of by-products also increases. From the above, the residual ozone concentration in the membrane filtration water is 0.01 to 10 mg / L, preferably 0.1 to 10 mg / L.
It is good to be 3 mg / L. Further, the device type of the ozone dissolving tank 19 may be any type such as a U-tube type, a diffuser type, an injector type, an ejector type, and a downward injection type injection. Further, the exhausted ozone gas discharged from the ozone dissolving tank 19 or the circulation tank 11 is introduced into the exhausted ozone gas processing equipment 13 and processed. The type of the exhaust ozone gas treatment equipment 13 may be any type such as an activated carbon type, a pyrolysis type, and a soot type.

Further, the membrane filtration device 4 after biological treatment in the present invention will be described. The membrane used is a membrane capable of removing turbid components and the like, and a microfiltration membrane or an ultrafiltration membrane is used. In the case of a microfiltration membrane, one having a nominal pore size of 0.01 to 0.5 μm is used. In the case of an ultrafiltration membrane, the molecular weight cut off is 1,000 to 20.
10,000 daltons are used. As the type of the membrane module, a hollow fiber shape, a spiral shape, a tubular shape, or a flat membrane shape is used. The filtration method of the membrane module is
There are a total filtration method and a cross flow filtration method, and any filtration method may be used. In addition, there are an external pressure type and an internal pressure type as a water flow system for the membrane filtration, and there is no problem with either water flow system.

Further, the latter-stage membrane filtration device 14 in the present invention will be described. The membrane filtration device filters the membrane in a state where ozone is dissolved in the membrane supply water, thereby preventing membrane clogging due to biological fouling. can do. And a high permeation flux can be obtained. The membrane used is a membrane capable of removing turbid components and bacteria, and a microfiltration membrane or an ultrafiltration membrane is used. In the case of microfiltration membrane, nominal pore size 0.01 ~
Those having a size of 0.5 μm are used. In the case of an ultrafiltration membrane, those having a molecular weight cut off of 1,000 to 200,000 daltons are used. As the type of the membrane module, a hollow fiber shape, a spiral shape, a tubular shape, or a flat membrane shape is used. It is desirable to use an ozone-resistant material for the film material and the potting portion in order to come into contact with high-concentration ozone. As the film material, an ozone-resistant organic resin such as a vinylidene fluoride polymer resin or an inorganic material such as a ceramic can be used. Further, the filtration method of the membrane module includes a total filtration method and a cross-flow filtration method, and any of the filtration methods may be used. In addition, there are an external pressure type and an internal pressure type as a water flow system for the membrane filtration, and there is no problem with either water flow system.

Next, ozone injection control in the present invention will be described. In the present embodiment, the ozone concentration is measured by operating the ozone generator 10 by measuring the residual ozone concentration in the membrane filtered water with the ozone detector 16. The ozone 9 generated by the ozone generator 10 is directly in-line injected into the pipe or supplied to the circulation tank 11 or the ozone dissolving tank 19, but the voltage applied to the ozone generator and valves provided in each supply pipe (not shown) It can be adjusted by adjusting the opening degree. In the ozone concentration injection control, the ozone concentration of the membrane supply water may be set as the control target value. In this case, even if the ozone is reacted with the clogging substance on the membrane surface even in a short time in membrane filtration, the ozone is consumed. Therefore, it is necessary to consider this in advance, and it is preferable to set the residual ozone concentration in the membrane filtered water as the control target value.

The injection rate of ozone is determined by feedback based on the residual ozone concentration in the membrane filtered water.
When the required amount of ozone in the supernatant obtained in the sedimentation tank 8 fluctuates, the residual ozone concentration in the membrane filtered water is measured by a dissolved ozone concentration detector, and the ozone injection rate is feedback-controlled. You can also. Of course, the ozone detector 16 may use a CPU (Central Processing Unit).

In the present invention, in addition to the above embodiment,
An ozone contact tank is further provided after the subsequent membrane filtration device 14,
A mode is also possible in which filtered water from the second membrane filtration device at the subsequent stage is supplied to the ozone contact tank, and ozone is re-injected into the ozone contact tank for treatment. Hereinafter, this aspect will be described.

In the embodiment shown in FIG. 4, the treatment device for human wastewater based on the present invention is a biological nitrification denitrification treatment device comprising a denitrification tank 2 and a nitrification tank 3, a membrane filtration device 4, a coagulation tank. 7, a sedimentation separation tank 8, a circulation tank 11, a membrane filtration device 14, an ozone contact tank 30, an ozone generator 10, an exhausted ozone gas treatment facility 13, an ozone detector 16, and an activated carbon adsorption tower 17. That is, the ozone contact tank 30
Is different from the embodiment of FIG.

First, as in the embodiment shown in FIG.
Flows into the denitrification tank 2 undiluted or diluted at an appropriate dilution ratio, and is supplied to the denitrification tank 2 and the nitrification tank 3.
And anaerobic nitrification and denitrification. The sewage subjected to the nitrification and denitrification treatment is subjected to solid-liquid separation by a membrane filtration device 4, and the biologically treated water 5 is transferred to a coagulation tank 7. In the coagulation tank 7, an inorganic coagulant 6 such as aluminum sulfate, ferric chloride, or polyiron is added to the biological treatment water 5 to coagulate the SS containing phosphate ions and COD. The flocculated floc is separated into a settled sludge and a supernatant liquid in a settling / separation tank 8, and the settled sludge is transferred to a sludge treatment step, and is incinerated after dehydration treatment. On the other hand, in the supernatant, ozone 9 is directly injected in-line from the ozone generator 10, and the water to be treated in which ozone is dissolved is sent to the circulation tank 11. The circulation tank 11 supplies the water to be treated to the membrane filtration device 14, and the membrane filtration water 15 that has passed through the membrane filtration device 14 is supplied to the ozone contact tank 30.
Sent to. In the ozone contact tank 30, a required amount of ozone 31 is supplied from the ozone generator 10, and the membrane filtered water 1 is supplied.
5 and ozone 31 are in contact. In the process of sending the membrane filtered water 15 from the membrane filtration device 14 to the ozone contact tank 30, the residual ozone concentration in the membrane filtered water is detected by the ozone detector 16, and based on the measured value of the ozone concentration, the ozone generator 10 is used. The supply amount of ozone 9 that is directly in-line injected from is controlled. The ozone-treated water 33 that has sufficiently contacted the ozone in the ozone contact tank 30 is transferred to the activated carbon adsorption tower 17 filled with activated carbon, and the treated water is discharged as effluent water 18 out of the system. Further, the exhausted ozone gas 12 discharged from the circulation tank 11 and the ozone contact tank 3
The exhausted ozone gas 32 discharged from 0 is processed in the exhausted ozone gas processing equipment 13. The circulating water from the membrane filtration device 14 is returned to the circulation tank 11 through a circulation line. Note that the same applies to the following embodiments, but the ozone detector 16 may be a dissolved ozone concentration detector.

In the present embodiment, the concentration of residual ozone in the membrane filtered water is constantly measured by the ozone detector 16, and the ozone generation is controlled so that the residual ozone concentration is in the range of 0.01 to 10 mg / L. The amount of ozone injected directly in-line from the device 10 is adjusted by the applied voltage of the ozone generator, the opening and closing operation of the valve, and the like. For example, C
The residual ozone concentration in the membrane filtration water is calculated by control means such as a PU (central processing unit), and the amount of ozone injected in-line is feedback-controlled.

Another example of the human wastewater treatment apparatus according to the present invention is shown in FIG.

As shown in FIG. 5, in the method and apparatus for treating human wastewater in this embodiment, the ozone 9 from the ozone generator 10 is the same as the embodiment in FIG. Instead of being injected into the water to be treated sent into the circulation tank 11 as described above, the water is injected into the circulation tank 11 and the ozone oxidation reaction is performed in the circulation tank 11. Otherwise, FIG.
This is the same as the embodiment.

Another example of the human wastewater treatment apparatus according to the present invention is shown in FIG.

In the embodiment of FIG. 6, the sedimentation separation tank 8
An ozone dissolving tank 19 is provided between the tank and the circulation tank 11, and ozone 9 from the ozone generator 10 is injected into the ozone dissolving tank 19. Otherwise, it is the same as the embodiment shown in FIG. That is, the supernatant liquid from the sedimentation separation tank 8 is supplied to the ozone dissolution tank 19, the ozone 9 is injected from the ozone generator 10 into the ozone dissolution tank 19, and the water to be treated in which ozone is dissolved is sent to the circulation tank 11. It is. Next, the treatment liquid is supplied from the circulation tank 11 to the membrane filtration device 14, and the membrane filtration water 15 that has passed through the membrane filtration device 14 is supplied to the ozone contact tank 3.
It is sent to 0. A required amount of ozone 31 is supplied from the ozone generator 10 to the ozone contact tank 30, and the membrane filtered water 15 and the ozone 31 are in contact. Membrane filtrate 15
Ozone contact tank 30 from membrane filtration device 14 is activated carbon adsorption tower 1
7, the ozone concentration remaining in the membrane filtration water is detected by the ozone detector 16, and the supply amount of ozone 9 supplied from the ozone generator 10 to the ozone dissolving tank 19 based on the measured value of the ozone concentration. Is controlled. The ozone treatment liquid 33 that has sufficiently contacted the ozone in the ozone contact tank 30 is transferred to the activated carbon adsorption tower 17 filled with activated carbon, and the treated water is discharged out of the system as discharge water 18. Further, the exhausted ozone gas 20 discharged from the ozone dissolving tank 19 and the exhausted ozone gas 1 discharged from the circulation tank 11
2 and the exhausted ozone gas 32 discharged from the ozone contact tank 30 are treated in the exhausted ozone gas treatment facility 13. The circulating water from the membrane filtration device 14 is returned to the circulation tank 11 through a circulation line.

The ozone dissolving tank 19 of the present invention, the membrane filtration device 4 after biological treatment, and the subsequent stage membrane filtration device 14
Is as described in the example of FIG.

Next, the injection control of ozone in the present invention will be described. In the present embodiment, the ozone concentration is measured by operating the ozone generator 10 by measuring the residual ozone concentration in the membrane filtered water with the ozone detector 16. Ozone 9 generated by the ozone generator 10 is directly in-line injected into a pipe or supplied to a circulation tank 11 or an ozone dissolving tank 19, and ozone 31 generated by the ozone generator 10 is supplied to an ozone contact tank 30. However, it can be adjusted by adjusting the applied voltage of the ozone generator and the opening of a valve (not shown) provided in each supply pipe. The injection control of the ozone concentration may be performed by setting the ozone concentration of the membrane supply water to the control target value.
Even in a short time in membrane filtration, the clogging substance on the membrane surface may react with ozone to consume ozone, so it is necessary to consider this in advance.Preferably, the residual ozone concentration in the membrane filtration water is reduced. It is desirable to set the control target value.

The injection rate of ozone is determined by feeding back the residual ozone concentration in the membrane filtered water.
When the required amount of ozone in the supernatant obtained in the sedimentation tank 8 fluctuates, the residual ozone concentration in the membrane filtered water is measured by a dissolved ozone concentration detector, and the ozone injection rate is feedback-controlled. You can also. Of course, the ozone detector 16 may use a CPU (Central Processing Unit).

Next, the ozone contact tank 30 according to the present invention will be described. In the embodiment of FIG. 6, an ozone contact tank 30 is provided downstream of the membrane filtration device 14. By providing an ozone contact tank after such a membrane filtration device,
Depending on the residual ozone concentration in the membrane filtration water, the ozone injection rate into the ozone contact tank can be adjusted, and the ozone treatment with the organic substance can be sufficiently performed. The purpose of the ozone contact tank 30 provided at the subsequent stage of the membrane filtration device 14 is to secure a contact time necessary for an ozone reaction with an organic substance,
The purpose is to re-inject ozone to replenish ozone required for the ozone reaction. The device type of the ozone contact tank 30 is a U-tube type, a diffuser type, an injector type,
Any form, such as down injection, is possible. However, ozone is dissolved in ozone-injected membrane filtration water, and it is not necessary to dissolve high-concentration ozone. The device type is preferably a diffuser type capable of ensuring a sufficient contact time. Since the exhaust gas is also generated in the ozone contact tank 30, the exhausted ozone gas is introduced into the exhausted ozone gas treatment equipment 13 and processed. The type of the exhaust ozone gas treatment equipment 13 may be any type such as an activated carbon type, a pyrolysis type, and a catalytic type.

[0047]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the method and apparatus for treating human wastewater according to the present invention will be described below. The present invention is not limited by the following examples.

(Example 1) In an experimental apparatus (throughput of 100 L / day) based on the conventional method flow shown in FIG. 7, a polyacrylonitrile polymer having a molecular weight cutoff of 20,000 daltons was formed on the membrane filtration device 4. Ultrafiltration membrane (total area 0.
A flat membrane of 2 m ² , a set flux of 0.5 m ³ / m ² / day) was applied, and a microfiltration membrane made of polypropylene having a nominal pore diameter of 0.2 μm (total area) was provided on the membrane filtration device 14 with an air backwash type. 0.1 m ² hollow fiber membrane, set flux 1.0 m ³ / m ²
/ Day), a treatment experiment of a mixed liquid of night soil and septic tank sludge was performed.

Starting from the operation up to the portion of the ultrafiltration flat membrane 4 in the conventional method shown in FIG. 7, after the acclimatization period of about one month and the biological treatment process is stabilized, And the operation experiment to the microfiltration hollow fiber membrane 14 was started. In coagulation sedimentation treatment, polyiron is converted to iron in 500
mg / L was added. The water quality data for each of the main steps in this experiment were as shown in Table 1.

[0050]

[Table 1] Here, the human wastewater 1 is a mixed liquid after removing human waste and sludge from a septic tank with a fine screen having an opening of about 1 mm. However, one week after starting the flow of water through the microfiltration hollow fiber membrane 14, the transmembrane pressure of the membrane exceeded 100 kPa, so that the flow of water through the membrane was interrupted, and sulfuric acid and Chemical cleaning with a sodium hydroxide solution was performed. A series of experiments was started again using the microfiltration hollow fiber membrane 14 after the chemical washing, but the transmembrane pressure exceeded 100 kPa one week after water flow was resumed.

Therefore, the experimental apparatus was constructed as shown in FIG.
Modified to flow. Here, the part of the membrane filtration device 4
In addition, polyacrylonitrile with a molecular weight cut off of 20,000 daltons
Tolyl polymer microfiltration membrane (total area 0.2m^TwoFlat membrane,
Setting flux 0.5m^Three/ M ^Two/ Day) and membrane filtration
In the part of the device 14, a vinylidene fluoride with a nominal pore size of 0.2 μm
Microfiltration membrane made of den-polymer resin (total area 0.03m^Twoin
Empty yarn membrane, setting flux 3.3m^Three/ M^Two/ Day)
Was. Residence in diffuser type ozone dissolution tank 19
The time is 10 minutes, and the residual ozone concentration in the membrane filtration water is:
The ozone dissolving tank 19 is set to 0.1 to 3 mg / L.
Dzon was injected and membrane filtration was performed. A series of water flow experiments
As a result, the transmembrane pressure in the microfiltration hollow fiber membrane 14 was determined.
Exceeded 100 kPa after 6 months from the start of water flow
Met. Therefore, using the method and apparatus of the present invention
Greatly increases the frequency of chemical cleaning of the nitrocellulose membrane 14 during microfiltration
It was found that it could be reduced. During this experiment,
Water quality data for each major process is as shown in Table 2.
You.

[0052]

[Table 2] Compared with the water quality data obtained by experiments using the conventional method and apparatus (Table 1), it was not found that there was a large difference in the water quality of human wastewater, but the membrane filtered water using the method and apparatus of the present invention was not found. Is lower than the COD and chromaticity of the membrane filtration water using the conventional method and apparatus, and the COD component and chromaticity contained in the biologically treated water by the method and apparatus of the present invention. It was found that the components had been treated well.

(Example 2) In an experimental apparatus (throughput of 100 L / day) based on the conventional method flow shown in FIG. 7, a polyacrylonitrile polymer having a molecular weight cutoff of 20,000 daltons was added to the membrane filtration unit 4. Microfiltration membrane (flat membrane with a total area of 0.2 m ² , set flux 0.5 m ³ / m ² /
), And a microfiltration membrane made of polypropylene having a nominal pore size of 0.2 μm (hollow fiber membrane having a total area of 0.1 m ² , setting flux 1.0)
m ³ / m ² / day), a treatment experiment of a mixed liquid of night soil and septic tank sludge was performed.

Starting from the operation up to the ultrafiltration flat membrane 4 in the conventional method shown in FIG. 7, after the acclimatization period of about one month, and the biological treatment process is stabilized, An operation experiment up to the apparatus and the microfiltration hollow fiber membrane 14 was started. Poly iron in coagulation sedimentation treatment
0 mg / L was added. The water quality data for each of the main steps in this experiment were as shown in Table 3.

[0055]

[Table 3] Here, the human wastewater 1 is a mixed liquid after removing human waste and sludge from a septic tank with a fine screen having an opening of about 1 mm. However, one week after starting the flow of water through the microfiltration hollow fiber membrane 14, the transmembrane pressure of the membrane exceeded 100 kPa, so that the flow of water through the membrane was interrupted, and sulfuric acid and Chemical cleaning with a sodium hydroxide solution was performed. A series of experiments was started again using the microfiltration hollow fiber membrane 14 after the chemical washing, but the transmembrane pressure exceeded 100 kPa one week after water flow was resumed.

Therefore, the experimental apparatus was modified to a flow as shown in FIG. Here, a microfiltration membrane made of a polyacrylonitrile polymer having a molecular weight cutoff of 20,000 daltons (a flat membrane having a total area of 0.2 m ² , and a set flux of 0.5 m ³ / m ² / ), And a microfiltration membrane made of a vinylidene fluoride polymer resin having a nominal pore size of 0.2 μm (total area: 0.03 m ²⁾
And a set flux of 3.3 m ³ / m ² / day). The residence time in the diffuser type ozone dissolving tank 19 is 6 minutes, and the residual ozone concentration in the membrane filtered water is as follows:
Ozone was injected into the ozone dissolving tank 19 so as to have a concentration of 0.1 to 3 mg / L, and membrane filtration was performed. The obtained membrane filtered water 15 was supplied to a diffuser type ozone contact tank 30, and 5 mg / L ozone was injected into the ozone contact tank 30 for treatment. As a result of a series of water passage experiments, the transmembrane pressure in the microfiltration hollow fiber membrane 14 exceeded 100 kPa after 6 months from the start of water passage, and by using the method and apparatus of the present invention. It has been found that the frequency of chemical cleaning of the microfiltration hollow fiber membrane 14 can be greatly reduced. In addition, the water quality data of each main process during this experimental period is as shown in Table 4.

[0057]

[Table 4] Compared with the water quality data obtained by experiments using the conventional method and apparatus (Table 3), there was no significant difference in the water quality of human wastewater, but the membrane filtered water using the method and apparatus of the present invention. Is lower than the COD and chromaticity of the membrane filtration water using the conventional method and apparatus, and the COD component and chromaticity contained in the biologically treated water by the method and apparatus of the present invention. It was found that the components had been treated well.

[0058]

As described above, according to the method and apparatus for treating human wastewater of the present invention, the biological wastewater of the human wastewater is subjected to a solid-liquid separation treatment using a membrane. A method and an apparatus in which a coagulant is added to a permeated liquid of a membrane, and then a sedimentation separation is performed and a solid-liquid separation treatment is performed by another membrane, thereby greatly reducing clogging of a subsequent membrane. This can reduce the labor required for chemical cleaning to cope with clogging of the membrane and the cost of cleaning chemicals, and can prolong the life of the membrane and reduce the membrane replacement cost.

Further, by controlling the injection of ozone, the amount of injected ozone can be minimized, and the consumption of ozone can be suppressed. Furthermore, a high quality of treated water can be obtained, the load on the activated carbon adsorption tower at the subsequent stage can be reduced, the frequency of replacement or regeneration of activated carbon can be reduced, and maintenance can be facilitated.

[Brief description of the drawings]

FIG. 1 is a diagram showing a processing flow of an embodiment of the present invention.

FIG. 2 is a diagram showing a processing flow of another embodiment of the present invention.

FIG. 3 is a diagram showing a processing flow of another embodiment of the present invention.

FIG. 4 is a diagram showing a processing flow of an embodiment of the present invention.

FIG. 5 is a diagram showing a processing flow of another embodiment of the present invention.

FIG. 6 is a diagram showing a processing flow of another embodiment of the present invention.

FIG. 7 is a diagram showing a processing flow of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Human wastewater, 2 ... Denitrification tank, 3 ... Nitrification tank, 4 ... Membrane filtration device, 5 ... Biologically treated water, 6 ... Flocculant, 7 ... Flocculant tank, 8
... sedimentation separation tank, 9 ... ozone, 10 ... ozone generator, 11
... circulation tank, 12 ... ozone exhaust gas, 13 ... ozone gas treatment equipment, 14 ... membrane filtration device, 15 ... membrane filtered water, 16 ... ozone detector, 17 ... activated carbon adsorption tower, 18 ... outflow water, 19
... Ozone dissolving tank, 20 ... Exhaust ozone gas, 30 ... Ozone contact tank, 31 ... Ozone, 32 ... Exhaust ozone gas, 33 ... Ozone treatment liquid

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C02F 9/00 504 C02F 9/00 504A 504E B01D 61/58 B01D 61/58 C02F 1/44 C02F 1/44 K 3 / 34 101 3/34 101A (72) Inventor Kenichiro Mizuno 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term in Nippon Kokan Co., Ltd. 4D006 GA06 GA07 KA01 KA72 KB12 KB13 KC03 KC14 KD08 KD19 KE30P KE30Q MA22 MB05 MC03 MC23 MC29 MC39 PB08 PC64 4D040 BB24 BB25 BB33 BB54 BB57 BB91

Claims (10)

[Claims] Claims: 1. After biologically treating human wastewater, a solid-liquid separation treatment is performed by a first membrane filtration device, and a coagulant is added to the permeate from the first membrane filtration device. After the addition, performing sedimentation separation in a sedimentation separation tank, and performing solid-liquid separation treatment on the supernatant liquid from the sedimentation separation tank with a second membrane filtration device, including human wastewater In the treatment method, an ozone injecting treatment is performed between the sedimentation separation tank and the circulation tank or the membrane supply tank to the second membrane filtration device, and the method includes the treatment of human wastewater. 2. An ozone contact tank is further provided after the second membrane filtration device, filtered water from the second membrane filtration device is supplied to the ozone contact tank, and ozone is returned to the ozone contact tank. The method for treating human wastewater according to claim 1, wherein ozone treatment is performed by injecting. 3. The human wastewater according to claim 1, wherein the membrane used for the first membrane filtration device and the second membrane filtration device is a microfiltration membrane or an ultrafiltration membrane. Processing method. 4. An ozone detector installed at a membrane filtration outlet of the second membrane filtration device so that a residual ozone concentration in the membrane filtration water is in a range of 0.01 to 10 mg / L.
2. The ozone injection amount is adjusted.
4. The method for treating human wastewater according to any one of claims 3 to 3. 5. The method according to claim 5, wherein the ozone injection amount is adjusted by continuously measuring the residual ozone concentration of the membrane filtration water by an ozone detector installed at a membrane filtration outlet of the second membrane filtration device. Based on the measured value, the ozone injection amount is feedback-controlled so that the residual ozone concentration in the membrane filtration water falls within a range of 0.01 to 10 mg / L, and the residual ozone concentration is adjusted within the range. The method for treating human wastewater according to claim 4, characterized in that: 6. The ozone is directly inline-injected into a pipe connecting the sedimentation separation tank and a circulation tank or a membrane supply tank to the second membrane filtration device.
6. The method for treating human wastewater according to any one of the above items 5. 7. The ozone is injected into a circulation tank or a membrane supply tank for the second membrane filtration device.
The method for treating human wastewater according to any one of claims 5 to 5. 8. An ozone dissolving tank is provided between the sedimentation separation tank and a circulation tank or a membrane supply tank for the second membrane filtration device, and ozone is injected into the ozone dissolving tank. The method for treating human wastewater according to any one of claims 1 to 5. 9. After biologically treating human wastewater, a solid-liquid separation treatment is performed by a first membrane filtration device, and a coagulant is added to the permeate from the first membrane filtration device. Thereafter, the sedimentation separation is performed in a sedimentation separation tank, and further, in a treatment device for human wastewater that performs a solid-liquid separation treatment by a second membrane filtration device, An ozone injection facility for injecting ozone in the middle of the membrane supply tank, an ozone detector for measuring the residual ozone concentration in the membrane filtration water installed at the membrane filtration outlet of the second membrane filtration device, and the ozone detector Measure the residual ozone concentration in the membrane filtration water, adjust the ozone injection amount by operating the ozone injection equipment based on the measured value, the residual ozone concentration present in the filtrate water from the second membrane filtration device Within the predetermined range Processor of human waste system sewage, characterized in that deploying and controlling means for controlling the so that. 10. The ozone contact tank is further provided after the second membrane filtration device to further ozone-treat the filtered water from the second membrane filtration device. An apparatus for treating human waste as described in the above.