JP2003094088A - Water treatment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment system capable of easily being composed. SOLUTION: This water treatment system 1 is provided with a storage tank 3 for storing waste water, and a biological treatment tank 5 for subjecting the biological treatment to the waste water from the storage tank 3. An air supply means 6 for supplying air which is necessary for the biological treatment inside the biological treatment tank 5 is arranged inside the biological treatment tank 5. A solid/liquid separation means 16 for separating solid/liquid of the waste water from the biological treatment tank 5 into sludge and treated water is connected to the biological treatment tank 5. A first return means 11 for returning the waste water inside the biological treatment tank 5 to the storage tank 3 is connected to the biological treatment tank 5. A second return means 21 for returning the sludge separated from the treated water to the storage tank 3 is connected to the solid/liquid separation means 16.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water treatment device having a simple structure.

[0002]

2. Description of the Related Art Conventionally, for example, in a landfill leachate, a combination of a storage tank, a biological treatment tank and a sedimentation tank has been used as a basic treatment method, and if necessary, the biological treatment tank is denitrified, nitrified or biochemical. Oxygen demand (Biochemical Oxygen
As an oxidation tank to reduce Demand: BOD), the process has been enhanced.

The waste water storage tank has been used for the purpose of storage and homogenization of water quality, and the sedimentation tank has been used for the purpose of mere solid-liquid separation. In addition, the aeration tank that aerated to supply dissolved oxygen and the denitrification tank that agitates in a closed water tank for the purpose of denitrification were used as biological treatment tanks.

As a treatment of excess sludge generated as a result of biological treatment, dehydration treatment and incineration treatment have been performed.
In recent years, in order to reduce this excess sludge treatment, the sludge from the settling tank is led to a water tank provided separately, and here, for example, the sludge is heated, ozone is injected, an alkaline agent is added, and special sludge is added. A method has been devised in which sludge is decomposed by, for example, culturing the bacteria of No. 3, and the decomposed sludge is returned to the biological treatment tank again.

However, these require complicated processing processes and simple processing equipment. In particular, the treatment of leachate discharged from the final disposal site is conventionally performed by pretreatment for removing calcium, biological treatment for removing organic substances such as BOD and ammonia, and chemical oxygen demand that is difficult to remove by biological treatment. (Chemical Oxygen Demand: COD)
It is composed of a coagulation treatment for removing heavy metals and heavy metals, sand filtration for removing suspended solids (SS) to a high degree, and an activated carbon adsorption tower and chelate adsorption tower as needed, which is extremely complicated. is there.

The properties of the leachate discharged from the final disposal site change depending on the years of landfill. BOD is high at the beginning of landfill and decreases as the years go by. On the other hand, dioxins, heavy metals, etc. are gradually reduced, but they are continuously discharged even after the landfill is completed. For this reason, it is necessary to operate the leachate treatment equipment for a while after the landfill is completed. Under the current law, if the landfill closure criteria are met, the leachate treatment facility can be shut down, but currently there is concern that dioxins and heavy metals will be emitted from the leachate for a long period after the landfill is completed. .

[0007] In such a state, at present, the operation is performed according to the above-mentioned processing flow, and the operation is not adapted to the property of the leachate. Especially, even after the landfill is completed, the operation continues with the current flow. Generally, both removal of BOD and removal of heavy metals are required at the initial stage of landfill, but removal of heavy metals is mainly required after completion of landfill.

It is necessary to improve efficiency by operating in accordance with such properties. Furthermore, when the leachate treatment facility needs to be renewed, the above flow will be reviewed and a simpler treatment will be required. Already in view of such a situation, as a simpler processing method, Japanese Patent Laid-Open No. 11-1289
The method described in No. 91 has been proposed. However, in this method, when the concentration of ammonia is high, it is simply changed to nitrate nitrogen and denitrification is impossible. Further, a coagulation tank for injecting a coagulant is provided, and the functionality is lacking.

[0009]

In recent years, there has been a strong demand for downsizing of the treatment equipment, and the development of a water treatment device having a simple structure has become an important issue.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a water treatment device having a simple structure.

[0011]

A water treatment apparatus according to claim 1 comprises a storage tank for adjusting and equalizing the amount and quality of the waste water, and a biological treatment tank for biologically treating the waste water from the storage tank. An air supply means for supplying air necessary for biological treatment in the biological treatment tank, a solid-liquid separation means for solid-liquid separating wastewater from the biological treatment tank into sludge and treated water, and the biological treatment tank The storage tank is provided with a first returning means for returning the waste water inside the storage tank to the storage tank, and a second returning means for returning the sludge separated from the treated water by the solid-liquid separation means to the storage tank. It is possible to add an additional function to the water treatment device, and the structure is simpler than that of the conventional water treatment device.

According to a second aspect of the present invention, in the water treatment apparatus according to the first aspect, the solid-liquid separation means solidifies the wastewater from the biological treatment tank into sludge and treated water by precipitating sludge. It has a settling tank for separation, and by allowing sludge to settle in the settling tank, the wastewater from the biological treatment tank can be appropriately solid-liquid separated into sludge and treated water.

A water treatment apparatus according to a third aspect of the present invention is a storage tank for adjusting and equalizing the amount and quality of wastewater, a biological treatment tank for biologically treating the wastewater from the storage tank, and a biological treatment tank in the biological treatment tank. From the biological treatment tank, an air supply means for supplying the air necessary for biological treatment in, and a filtering means for passing a part of the wastewater from the biological treatment tank as treated water and returning the rest to at least the storage tank. Since the storage tank is provided with a returning means for returning the sludge, the storage tank can be provided with an additional function, and the structure is simpler than that of the conventional water treatment apparatus.

According to a fourth aspect of the present invention, in the water treatment apparatus according to the third aspect, the filtering means has a filtration membrane composed of a tubular type ultrafiltration membrane or a tubular microfiltration membrane. Therefore, the waste water can be appropriately filtered by using a filtration membrane constituted by a tubular type ultrafiltration membrane or a tubular microfiltration membrane.

According to a fifth aspect of the present invention, in the water treatment apparatus according to the third or fourth aspect, the air supply means is configured to supply air using an ejector and an opening / closing valve. The air can be appropriately supplied using the ejector and the on-off valve with a simple structure.

A water treatment apparatus according to a sixth aspect of the present invention is a storage tank for adjusting and equalizing the amount and quality of wastewater, a biological treatment tank for biologically treating the wastewater from the storage tank, and the inside of the biological treatment tank. And an air supply means for supplying the air necessary for biological treatment in the biological treatment tank, and is immersed in the wastewater in the biological treatment tank, and a part of the wastewater in the biological treatment tank is passed as treated water to the outside of the biological treatment tank. It is provided with a filtering means for discharging and a returning means for returning wastewater from the biological treatment tank to the storage tank, and the storage tank can have an additional function,
The configuration is simpler than that of a conventional water treatment device.

According to a seventh aspect of the present invention, in the water treatment apparatus according to the sixth aspect, the filtering means has a filtration membrane composed of an immersion type ultrafiltration membrane or an immersion type microfiltration membrane. The drainage can be appropriately filtered by using a filtration membrane composed of an immersion type ultrafiltration membrane or an immersion type microfiltration membrane.

The water treatment apparatus according to claim 8 is the water treatment apparatus according to any one of claims 1 to 7, further comprising an addition means for adding at least one of a coagulant and activated carbon to the wastewater. At least one of the coagulant and activated carbon can be appropriately added to the wastewater by the addition means.

The water treatment apparatus according to claim 9 is the water treatment apparatus according to claim 8, wherein ferric chloride or aluminum chloride is used as the coagulant, and ferric chloride or aluminum chloride is used as the coagulant. By using it, it is possible to appropriately aggregate the dispersed particles in the wastewater.

The water treatment apparatus according to claim 10 is the same as that according to claim 1.
9. The water treatment apparatus according to any one of 1 to 9, wherein the in-tank solution pH of the biological treatment tank is controlled to 5.8 to 8.6, and the in-tank liquid pH of the biological treatment tank is set to 5.8 to 8 By controlling to 6 the atmosphere inside the biological treatment tank becomes suitable for biological treatment.

The water treatment device according to claim 11 is the water treatment device according to claim 1.
The water treatment apparatus according to any one of 1 to 10 is provided with a withdrawing unit for withdrawing the excess sludge in the storage tank, and the withdrawing unit can appropriately extract the excess sludge from the storage tank.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The first embodiment of the water treatment device of the present invention will be described below.
The configuration of the embodiment will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a water treatment device, which is an organic sewage containing organic substances such as sewage, and a leachate sewage (B) after landfill at a landfill site.
Waste water such as OD, COD, ammoniacal nitrogen, and leachate containing heavy metals) is purified so as not to contaminate the public water area of the discharge destination.

This water treatment device 1 is equipped with a storage tank 3 for adjusting and equalizing the amount and quality of waste water.
Is for directly receiving and temporarily storing wastewater having unstable water quantity and water quality discharged from the inflow pipe 2 and the like, and stabilizing the water quantity and water quality of the wastewater on the downstream side. No other tank is provided on the upstream side of the storage tank 3.

In the water treatment device 1, the wastewater that has flowed out from the storage tank 3 through the outflow pipe 4 in a state where the amount and quality of water have been adjusted and equalized is biologically treated by aerobic microorganisms under aerobic conditions. A biological treatment tank 5 for treatment (nitrification treatment, etc.) is provided.

Oxygen-containing air necessary for biological treatment in the biological treatment tank 5 is supplied into the biological treatment tank 5, and the air, the wastewater to be treated, and the sludge floating in the wastewater (floating sludge). An air supply means 6, which is an agitating means for stirring and mixing in the biological treatment tank 5, is arranged in the biological treatment tank 5.

A coagulant injection means 7 which is a coagulant injection facility for injecting a coagulant (for example, ferric chloride or aluminum chloride) into the biological treatment tank 5 is connected to the biological treatment tank 5 and activated carbon is also used. Activated carbon injection means 8 which is an activated carbon injection facility for injecting (for example, granular activated carbon or powdered activated carbon) into the biological treatment tank 5 is connected to the biological treatment tank 5. The coagulant injecting means 7 and the activated carbon injecting means 8 constitute an adding means 9 for adding both the coagulant and the activated carbon to the waste water.

Further, the wastewater in the biological treatment tank 5 (a mixed solution which is a liquid in the biological treatment tank), that is, the wastewater containing nitrite nitrogen and nitrate nitrogen generated by the nitrification treatment, is stored in the upstream storage tank. The first returning means 11 such as a mixed solution circulation line for returning to 3 is connected to the biological treatment tank 5. The first return means 11 has a connecting pipe 12 which is located between the storage tank 3 and the biological treatment tank 5 and connects the storage tank 3 and the biological treatment tank 5 to each other, and a return pump is provided in the middle of the connecting pipe 12. 13 are provided. The pH of the in-tank solution of the biological treatment tank 5, that is, the pH of the wastewater in the biological treatment tank 5 is controlled to 5.8 to 8.6 so that the biological treatment tank 5 has an atmosphere suitable for biological treatment. .

Further, the water treatment apparatus 1 is provided with a solid-liquid separation means 16 for solid-liquid separating the wastewater (biologically treated liquid) flowing out from the biological treatment tank 5 through the outflow pipe 15 into sludge and treated water. There is.

The solid-liquid separating means 16 causes the wastewater from the biological treatment tank 5 to be sludge (precipitated sludge) and treated water (supernatant water), for example, by precipitating sludge in the lower part (sedimentation and separation of sludge).
And a sedimentation tank 17 for solid-liquid separation.

Then, the treated water separated from the sludge by the settling tank 17 is discharged from the settling tank 17 through the discharge pipe 18. The sludge separated from the treated water in the settling tank 17 is returned to the storage tank 3 from the settling tank 17 by the second returning means 21 such as a sludge returning line together with the returning liquid.

The second returning means 21 has a connecting pipe 22 located between the storage tank 3 and the settling tank 17 for connecting the storage tank 3 and the settling tank 17 to each other. A pump 23 is provided.

Then, in the storage tank 3 where the drainage in the biological treatment tank 5 and the sludge in the settling tank 17 are returned by the first returning means 11 and the second returning means 21, the first returning means 11 returns the sludge. Denitrification treatment is performed by anaerobic microorganisms under an anaerobic condition, using wastewater containing nitrite nitrogen and nitrate nitrogen as an oxygen source and sludge returned by the second returning means 21 as a carbon source.

The storage tank 3 is connected to a withdrawing means 25 for withdrawing excess sludge in the storage tank 3 together with unsuitable substances for biological reaction in the waste water in the storage tank 3. This withdrawal means 25 is
The drawing tube 26, the drawing pump 27, and the like.

Next, the wastewater treatment by the water treatment device 1 will be described.

The inside of the biological treatment tank 5 becomes aerobic by the air supply by the air supply means 6, and within the biological treatment tank 5,
Biological treatment is performed under aerobic conditions, and nitrite nitrogen and nitrate nitrogen are generated by the oxidation of ammonia nitrogen.

A part of the waste water containing the generated nitrite nitrogen and nitrate nitrogen is returned to the storage tank 3 by the first return means 11 by the operation of the return pump 12. In addition, the sludge is returned to the storage tank 3 by the second return means 21 from the settling tank 17 by the operation of the return pump 23 together with the return liquid. Sludge creates a condition that is prone to self-degradation due to its long residence time.

Then, in the storage tank 3, a mixed liquid, which is waste water containing nitrite nitrogen and nitrate nitrogen from the biological treatment tank 5, is used as an oxygen source, and the waste water from the inflow pipe 2 and the sedimentation tank 17 are supplied. Denitrification is performed under anaerobic conditions by using the settled sludge as a carbon source, and harmless nitrogen gas is generated.

In this way, the wastewater is stored in the storage tank 3, the outflow pipe 4,
By circulating the biological treatment tank 5 and the first returning means 11, nitrification treatment, denitrification treatment, and the like are performed, and the treated wastewater is guided from the outflow pipe 15 to the settling tank 17 and solid-liquid inside the settling tank 17. The wastewater that has been separated and the sludge has been separated and removed is discharged from the discharge pipe 18 as treated water.

The BOD concentration of the wastewater in the storage tank 3 is 2
When it is from 0 to 1000 mg / L, it is desirable to set the retention time of the sedimentation sludge in the sedimentation tank 17 to be 20 to 30 hours in order to facilitate self-decomposition of the sedimentation sludge.
Further, in order to increase the concentration of the settled sludge in the return liquid returned to the storage tank 3, a flocculant such as ferric chloride is added by the addition means 9 to adjust the settled sludge concentration to 10,000 to 2000.
It is desirable to set it to 0 mg / L.

Further, the unsuitable biological reaction substances contained in the waste water in the storage tank 3 are drawn out by the drawing means 25 together with the surplus sludge generated in this step, which facilitates the maintenance of the subsequent steps.

Further, according to the water treatment apparatus 1 described above, the storage tank 3 has a denitrification treatment function in addition to the function of adjusting and equalizing the amount and quality of the wastewater, and thus the conventional water treatment apparatus is used. In comparison, the structure can be simplified, the processing equipment can be made compact, and the sludge can be reduced.

Next, the configuration of the second embodiment of the water treatment apparatus of the present invention will be described with reference to the drawings.

In FIG. 2, reference numeral 1a denotes a water treatment device, which is an organic sewage containing organic substances such as sewage, and a leachate sewage (B
Waste water such as OD, COD, ammoniacal nitrogen, and leachate containing heavy metals) is purified so as not to contaminate the public water area of the discharge destination.

The water treatment device 1a is provided with a storage tank 32 for adjusting and equalizing the amount and quality of waste water.
Is for directly receiving and temporarily storing wastewater with unstable water quantity and water quality discharged from the inflow pipe 31 and the like, and stabilizing the water quantity and water quality of the wastewater on the downstream side. Note that another tank is not provided on the upstream side of the storage tank 32.

Further, the water treatment device 1a uses wastewater discharged from the storage tank 32 through the outflow pipe 33 due to overflow or the like in a state where the amount and quality of water are adjusted and made uniform by aerobic microorganisms under aerobic conditions. The biological treatment tank 34 such as a circulation tank for biological treatment (nitrification treatment, etc.) is provided.

The biological treatment tank 34 is connected to a coagulant injection means 35 which is a coagulant injection facility for injecting a coagulant (for example, ferric chloride or aluminum chloride) into the biological treatment tank 34. Further, the biological treatment tank 34 is connected to activated carbon injection means 36 which is an activated carbon injection facility for injecting activated carbon (eg granular activated carbon or powdered activated carbon) into the biological treatment tank 34. Coagulant injection means 35 and activated carbon injection means 36 constitute addition means 37 for adding both the coagulant and activated carbon to the wastewater.

Further, the biological treatment tank 34 is connected to the upstream side which is the circulation inlet side of the tubular membrane separation means 41 which is made into one unit, via a first circulation line 43 having a circulation pump 42. . The tubular membrane separation means 41 has a cylindrical tubular type filtration membrane 44 composed of a tubular ultrafiltration membrane (UF) or a tubular microfiltration membrane (MF) and contains sludge. A part of the wastewater passes through the filtration membrane 44 so as to seep from the inner circumference side to the outer circumference side of the filtration membrane 44, and becomes treated water (membrane filtration water) from which sludge and the like have been separated and removed, and is discharged from the discharge pipe 45. It The downstream side, which is the circulation outlet side of the tubular membrane separation means, is connected to the biological treatment tank 34 via a second circulation line 47.

In the middle of the second circulation line 47, an air injecting means 50 which is an air supplying means such as an agitating means for injecting air into the second circulation line 47 at any time is connected.
The air injection means 50 supplies oxygen-containing air necessary for biological treatment in the biological treatment tank 34, and uses the ejector 51 and the opening / closing valve 52 to inject air into the second circulation line 47. It is composed. By the opening / closing control of the opening / closing valve 52, which is an automatic opening / closing valve, by the control means (not shown),
Injecting air into the second circulation line 47 or the second circulation line
It is possible to prohibit the injection of air into 47.

In the middle of the second circulation line 47 (upstream side from the air injection position), waste water which is a circulating liquid from the second circulation line 47 to the storage tank 32 (by nitrification treatment in the biological treatment tank 34) The upstream end of a third circulation line 53 for returning the generated mixed liquid, which is waste water containing nitrite nitrogen and nitrate nitrogen, is connected, and the lower end of the third circulation line 53 is a storage tank.
Connected to 32.

Then, a part of the waste water flowing out from the biological treatment tank 34 is filtered and passed as treated water, and the rest that has not passed is returned to both the biological treatment tank 34 and the storage tank 32. The circulation pump 42, the first circulation line 43, the tubular membrane separation means 41, the second circulation line 47 and the third
It is composed of a circulation line 53. First circulation line 43,
The second circulation line 47 and the third circulation line 53 constitute a circulation line 56.

The pH of the in-tank liquid of the biological treatment tank 34, that is, the pH of the waste water which is a mixed liquid in the biological treatment tank 34 is 5.8 to so that the biological treatment tank 34 has an atmosphere suitable for biological treatment.
Controlled to 8.6. In addition, the biological treatment tank 34 which is a circulation tank
It is desirable that the sludge concentration of the wastewater of 10000 to 20000 mg / L.

On the other hand, the water treatment device 1a includes a biological treatment tank 34
The storage means 32 is provided with a return means 57 for returning the sludge (concentrated sludge) together with the return liquid. This returning means 57 has a connecting pipe 58 which is located between the storage tank 32 and the biological treatment tank 34 and connects the storage tank 32 and the biological treatment tank 34 with each other, and a return pump 59 is provided in the middle of the connecting pipe 58. It is provided.

Then, in the storage tank 32, sludge and the like returned by the return means 57 using wastewater containing nitrite nitrogen and nitrate nitrogen returned by the filtration means 55 through the third circulation line 53 as an oxygen source. Using carbon as a carbon source, denitrification is performed by anaerobic microorganisms under anaerobic conditions. Note that the storage tank 32 is connected to a drawing means 61 for drawing out excess sludge in the storage tank 32 together with unsuitable substances for biological reaction in the waste water in the storage tank 32. The drawing means 61 is composed of a drawing pipe 62, a drawing pump 63, and the like.

Next, the wastewater treatment by the water treatment device 1a will be described.

The inside of the biological treatment tank 34 becomes aerobic by the air supply by the air injection means 50. That is, the circulation line
When the flow of the wastewater circulating through the second circulation line 47 of 56 is used as a “driving force”, and air containing oxygen in the atmosphere is added to the wastewater by the ejector 51 and is entrained in the wastewater,
The atmosphere of the liquid in the biological treatment tank 34 becomes aerobic. Then, in the biological treatment tank 34, biological treatment is performed under an aerobic condition, and BOD and ammonia nitrogen in the wastewater are oxidized. Oxidation of ammoniacal nitrogen produces nitrite nitrogen and nitrate nitrogen.

A part of the generated waste water containing nitrite nitrogen, nitrate nitrogen and the like passes through the first circulation line 43 by the circulation pump 42 and is a filtration membrane which is a tubular membrane of the tubular membrane separation means 41. It is introduced on the inner circumference side of 44.

A part of the wastewater introduced to the inner peripheral side of the filtration membrane 44 is bleeding from the inner peripheral side to the outer peripheral side.
It passes through 44 and is discharged as treated water that does not contain sludge. The rest that did not pass through the filtration membrane 44 is the second circulation line.
Although it returns to the biological treatment tank 34 through 47, a part thereof is returned to the storage tank 32 through the third circulation line 53.

Further, the sludge in the biological treatment tank 34 is returned from the biological treatment tank 34 to the storage tank 32 by the return means 57 by the operation of the return pump 59.

In the storage tank 32, the third circulation line
Denitrification under anaerobic conditions using a mixed liquid, which is wastewater containing nitrite nitrogen and nitrate nitrogen from 53, as an oxygen source, and drainage from the inflow pipe 31 and sludge from the biological treatment tank 34 as a carbon source. And harmless nitrogen gas is generated.

In this way, the wastewater is stored in the storage tank 32, the outflow pipe 33,
By circulating the biological treatment tank 34 and the filtration means 55, nitrification treatment, denitrification treatment, and the like are performed, and the waste water after the treatment that has passed through the filtration membrane 44 is discharged from the discharge pipe 45 as treated water.

When leachate is treated as waste water, ferric chloride or aluminum chloride coagulant is added to the circulating waste water by the addition means 37. Then, the heavy metal, which is the colloidal dispersed particles in the waste water, aggregates as a hydroxide and is coarsened to form flocs (floc-like oxides) of a predetermined size.

This floc is larger than the pores on the surface (filtration surface) of the filtration membrane 44 and cannot pass through the filtration membrane 44.
Since the wastewater is separated from the wastewater, part of the wastewater becomes treated water that does not contain heavy metals.
It is separated by filtration by 44.

Also, the surface of the filtration membrane 44 (filtration surface) is contaminated by the adherence of scales etc. with the lapse of operating time, but the flocs flowing with the drainage rub against the surface of the filtration membrane 44, and due to the abrasion of the flocs. The surface of the filtration membrane 44 is washed, and the passage ability of the filtration membrane 44 is maintained.

At this time, when the concentration of BOD and ammonia nitrogen in the waste water is low, the in-tank liquid p of the biological treatment tank 34
The H is controlled to be around 5 to 6 and set in the optimum range for the aggregation and separation treatment of heavy metals. However, when the concentration of BOD and ammonia nitrogen in the wastewater is high, the biological treatment tank 34
The pH of the liquid in the tank of the biological treatment tank is controlled to be 5.8 to 8.6.
The inside is set to an atmosphere suitable for biological treatment that is performed at the same time as the heavy metal coagulation separation treatment.

On the other hand, when activated carbon is added to the circulating waste water by the addition means 37, the hardly decomposable COD in the waste water is adsorbed and removed by the adsorbing action of the activated carbon. The activated carbon flows with the leachate and rubs the surface of the filtration membrane 44, and the surface of the filtration membrane 44 is washed by rubbing the activated carbon.
44 passage ability is maintained.

Further, the unsuitable biological reaction substances contained in the wastewater in the storage tank 32 are extracted by the extraction means 61 together with the surplus sludge generated in this step, which facilitates the maintenance of the subsequent steps.

Further, according to the water treatment device 1a, the storage tank 32 has a denitrification treatment function in addition to the functions of adjusting and equalizing the amount and quality of the waste water. In comparison, the structure can be simplified, the processing equipment can be made compact, and the sludge can be reduced.

Further, the superiority becomes remarkable especially in the treatment of leachate. That is, despite the simple structure, heavy metals and persistent COD can be removed, and air is intermittently entrained in the circulation line 56 to allow BOD.
And ammonia can be removed, and the process flow can be simplified compared to the conventional process flow.

Further, the water treatment device 1a as the leachate treatment device is to obtain stable water quality by using the filtration membrane 44. A filter membrane is used for leachate that is the wastewater that contains the scale found in leachate discharged from landfills.
In the case of using 44, it is necessary to rub the membrane surface at all times so as to prevent the membrane surface from being clogged with scale or the like to prevent the accumulation of scale. To this end, ferric chloride or the like is used as a coagulant to form a metal hydroxide, and powdered activated carbon is injected if necessary, so that these substances promote abrasion of the film surface, Prevents buildup of scale on the surface. A tubular type membrane is adopted as the filtration membrane 44 having such a function.

However, when the tubular type filtration membrane 44 is used, the circulation pump 42 is required. The circulation pump 42 normally has about 490 to 686 kPa (5 to 5
It requires a pump pressure of 7 kg / cm ²⁾ and is not economically superior. In order to eliminate this, in the water treatment device 1a,
The residual pressure of the leachate, which is the circulating liquid that is made to flow in the second circulation line 47 by the circulation pump 42, is approximately 294 to 4.
Focusing on the fact that the pressure is 90 kPa (3 to 5 kg / cm ² ), the suction type air injection means 50 using the ejector 51 was adopted. As a result, the air supply means for biological treatment, which was conventionally required, is no longer required. Further, when the tubular type filtration membrane 44 is used, it is sufficient that the circulation pump 42 has a large flow rate and the return pump 59 has a small capacity. In some cases, the return pump 59 can be unnecessary.

Furthermore, the biological treatment tank 34 by the ejector 51
It is not necessary to stir the liquid in the tank, and it is not necessary to install sand filtration and sedimentation equipment that were required by the use of the filtration membrane 44, and to install an activated carbon adsorption tower by injecting activated carbon by the activated carbon injection means 36. Nor. In addition, since the sludge concentration of the liquid in the biological treatment tank 34 can be maintained at a high concentration by the filtration membrane 44, it is not necessary or necessary to replenish the carbon source necessary for denitrification.

Next, the configuration of the third embodiment of the water treatment apparatus of the present invention will be described with reference to the drawings.

In FIG. 3, reference numeral 1b is a water treatment device. This water treatment device 1b is an organic sewage containing organic substances such as sewage, a leachate sewage (B
Waste water such as OD, COD, ammoniacal nitrogen, and leachate containing heavy metals) is purified so as not to contaminate the public water area of the discharge destination.

This water treatment device 1b is provided with a storage tank 72 for adjusting / uniformizing the amount and quality of waste water.
Is for directly receiving and temporarily storing wastewater having unstable water quantity and water quality discharged from the inflow pipe 71 and the like, and stabilizing the water quantity and water quality of the wastewater on the downstream side. No other tank is provided upstream of the storage tank 72.

In addition, the water treatment device 1b uses the aerobic microorganisms to biologically treat the wastewater that has flowed out from the storage tank 72 through the outflow pipe 73 with the amount and quality of water adjusted and made uniform. A biological treatment tank 74 such as a dipping tank for performing treatment (nitrification treatment, etc.) is provided.

Then, oxygen-containing air necessary for biological treatment in the biological treatment tank 74 is supplied into the biological treatment tank 74, and the air, waste water to be treated, and sludge (floating sludge) floating in the waste water are supplied. An air supply means 75, which is a stirring means for agitating and mixing in the biological treatment tank 74, is arranged in the biological treatment tank 74.

A coagulant injection means 78, which is a coagulant injection facility for injecting a coagulant (for example, ferric chloride or aluminum chloride) into the biological treatment tank 74, is connected to the biological treatment tank 74, and the activated carbon is used. An activated carbon injection means 76, which is an activated carbon injection facility for injecting (for example, granular activated carbon or powdered activated carbon) into the biological treatment tank, is connected to the biological treatment tank 74. Coagulant injection means 78 and activated carbon injection means 76 constitute addition means 77 for adding both the coagulant and activated carbon to the wastewater.

Further, the wastewater in the biological treatment tank 74 (a mixed solution which is the liquid in the biological treatment tank), that is, it contains sludge at a high concentration and contains nitrite nitrogen and nitrate nitrogen generated by nitrification treatment. Wastewater storage tank upstream from biological treatment tank 74
Returning means 81 such as a mixed liquid circulation line for returning to 72 is connected to the biological treatment tank 74.

The return means 81 is located between the storage tank 72 and the biological treatment tank 74, and the storage tank 72 and the biological treatment tank 74 are located between them.
It has a connecting pipe 82 for connecting each other, and a return pump 83 is provided in the middle of the connecting pipe 82. It should be noted that the biological treatment tank 74 has an atmosphere suitable for biological treatment so that the biological treatment tank 74 has an atmosphere suitable for biological treatment.
The pH of the in-tank liquid, that is, the pH of the wastewater in the biological treatment tank 74 is 5.
It is controlled to 8 to 8.6.

Further, the water treatment device 1b is partially disposed in the wastewater in the biological treatment tank 74, and a portion of the wastewater in the biological treatment tank 74 is filtered so as not to contain sludge or the like. It is equipped with a submerged type filtration means 85 for passing as (membrane filtered water) and discharging it to the outside of the biological treatment tank 74.

The filtering means 85 is a tubular type ultrafiltration membrane (UF) or a tubular microfiltration membrane (MF).
Has a submerged filtration membrane 86, and part of the wastewater containing sludge passes through the filtration membrane 86 to become treated water (membranous filtration water) from which sludge has been separated and removed. Emitted from 87. A treated water pump 88 is provided in the middle of the discharge pipe 87. The entire filtration membrane 86 is immersed in the waste water in the biological treatment tank 74.

The storage tank 72 is connected with a drawing means 91 for drawing the excess sludge in the storage tank 72 together with the biological reaction unsuitable substances in the waste water in the storage tank 72. This withdrawal means 91 is
The drawing tube 92, the drawing pump 93, and the like.

Next, the wastewater treatment by the water treatment device 1b will be described.

The inside of the biological treatment tank 74 becomes aerobic by the air supply by the air supply means 75, and in the biological treatment tank 74,
Biological treatment is performed under aerobic conditions, and nitrite nitrogen and nitrate nitrogen are generated by the oxidation of ammonia nitrogen.

A part of the discharged water (returned liquid) containing the generated nitrite nitrogen and nitrate nitrogen is returned to the storage tank 72 by the return means 81 by the operation of the return pump 83. At the same time, sludge is returned to the storage tank by the return means 81 together with this return liquid.
Returned to 72.

Then, in the storage tank 72, a mixed liquid which is a return liquid containing nitrite nitrogen and nitrate nitrogen from the biological treatment tank 74 is used as an oxygen source, and drainage from the inflow pipe 71 and the biological treatment tank are used. The sludge from 74 is used as a carbon source for denitrification under anaerobic conditions, and harmless nitrogen gas is generated.

In this way, the wastewater is stored in the storage tank 72, the outflow pipe 73,
By circulating the biological treatment tank 74 and the returning means 81, nitrification treatment, denitrification treatment, and the like are performed. Wastewater after treatment is
By the operation of the treated water pump 88, solid-liquid separation is carried out by the filtration membrane 86, and the sludge is discharged from the discharge pipe 87 as treated water.

Further, the unsuitable substances for biological reaction contained in the waste water in the storage tank 72 are withdrawn by the withdrawing means 91 together with the surplus sludge generated in this step, and the maintenance of the subsequent steps becomes easy.

According to the above-mentioned water treatment device 1b, the storage tank 72 is provided with a denitrification treatment function in addition to the function of adjusting and equalizing the amount and quality of the wastewater, so that the conventional water treatment device can be used. In comparison, the structure can be simplified, the processing equipment can be made compact, and the sludge can be reduced.

In the first embodiment described above, the solid-liquid separating means 16 is described as being composed of the settling tank 17, but
Other configurations may be used.

In the second embodiment, the air supply means such as the air injection means 50 injects the air into the second circulation line 47, but the first circulation line has been described.
The configuration may be such that air is injected into the biological treatment tank 43, air is injected into the biological treatment tank 34 located inside the biological treatment tank 34, or the ejector 51 and the on-off valve 52 are not used.

Further, the filtering means 55 is limited to a construction in which a part of the wastewater flowing out from the biological treatment tank 34 is passed as treated water and the rest which is not passed is returned to both the biological treatment tank 34 and the storage tank 32. Instead, the rest that did not pass may be returned only to the storage tank 32.

Further, the adding means 37 is not limited to the structure of injecting it into the biological treatment tank 34 and adding it to the wastewater, and injecting it into the first circulation line 43, the second circulation line 47, etc. to add it to the wastewater. It may be configured.

[0095]

According to the invention described in claim 1, the sludge separated from the treated water by the second returning means by returning the wastewater in the biological treatment tank to the storage tank by the first returning means and by the second returning means. By returning the water to the storage tank, the storage tank can be provided with an additional function, and the configuration can be simplified as compared with the conventional water treatment device.

According to the second aspect of the present invention, the sludge is settled in the settling tank, so that the wastewater from the biological treatment tank can be appropriately solid-liquid separated into sludge and treated water.

According to the third aspect of the invention, a part of the waste water from the biological treatment tank is passed as treated water by the filtering means and the rest is returned to at least the storage tank, and the sludge from the biological treatment tank to the storage tank is returned by the returning means. By returning the water, the storage tank can be provided with an additional function, and the configuration can be simplified as compared with the conventional water treatment device.

According to the fourth aspect of the invention, the waste water can be properly filtered by using the filtration membrane constituted by the tubular type ultrafiltration membrane or the tubular type microfiltration membrane.

According to the fifth aspect of the invention, air can be appropriately supplied by utilizing the ejector and the opening / closing valve with a simple structure.

According to the sixth aspect of the present invention, there is provided filtration means for immersing the wastewater in the biological treatment tank so that a part of the wastewater in the biological treatment tank passes as treated water and is discharged to the outside of the biological treatment tank. Since the structure is provided with the returning means for returning the wastewater from the biological treatment tank to the storage tank, the storage tank can be provided with an additional function, and the structure can be simplified as compared with the conventional water treatment apparatus.

According to the invention described in claim 7, the drainage can be properly filtered by using the filtration membrane constituted by the immersion type ultrafiltration membrane or the immersion type microfiltration membrane.

According to the invention described in claim 8, at least one of the coagulant and the activated carbon can be appropriately added to the waste water by the addition means.

According to the invention described in claim 9, by using ferric chloride or aluminum chloride as the coagulant, the dispersed particles in the waste water can be appropriately coagulated.

According to the tenth aspect of the present invention, the inside of the biological treatment tank can be made into an atmosphere suitable for biological treatment by controlling the pH of the liquid inside the biological treatment tank to 5.8 to 8.6.

According to the eleventh aspect of the present invention, the excess sludge can be appropriately extracted from the storage tank by the extracting means.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a water treatment device of the present invention.

FIG. 2 is a diagram showing a second embodiment of the water treatment device of the present invention.

FIG. 3 is a diagram showing a second embodiment of the water treatment device of the present invention.

[Explanation of symbols]

1,1a, 1b Water treatment equipment 3,32,72 storage tanks 5,34,74 Biological treatment tank 6,50,75 Air supply means 9,37,77 Addition means 11 First return means 16 Solid-liquid separation means 17 Settling tank 21 Second return means 25, 61, 91 Extraction means 44,86 filtration membrane 51 ejector 52 Open / close valve 55,85 Filtration means 57,81 Means of return

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C02F 1/44 C02F 1/44 F 1/52 1/52 K (72) Inventor Kazuhiko Tanaka Osaka City, Osaka Prefecture Nishi Ward 2-chome, 1-chome, Ataka Kogyo Co., Ltd. F-term (reference) 4D006 GA06 GA07 HA21 KA01 KA03 KA33 KA71 KB13 KB22 KB23 KD08 KD19 MA02 PB08 PC63 4D015 BA04 BA19 BA23 BB05 CA02 DA03 DA13 EA32 EA37 FA01 FA04 401024 A02 BB01 BC04 DB05 DB15 DB16 DB21 4D028 AB00 AC01 AC04 BB07 BD12 BD16

Claims (11)

[Claims] 1. A storage tank for adjusting / uniformizing the amount and quality of wastewater, a biological treatment tank for biologically treating the wastewater from the storage tank, and air necessary for biological treatment in the biological treatment tank. Means for supplying air, solid-liquid separation means for solid-liquid separating the wastewater from the biological treatment tank into sludge and treated water, and first returning means for returning the wastewater in the biological treatment tank to the storage tank And a second returning means for returning the sludge separated from the treated water by the solid-liquid separating means to the storage tank. 2. The water treatment system according to claim 1, wherein the solid-liquid separation means has a settling tank for solid-liquid separating the wastewater from the biological treatment tank into sludge and treated water by precipitating sludge. apparatus. 3. A storage tank for adjusting / uniformizing the amount and quality of wastewater, a biological treatment tank for biologically treating the wastewater from the storage tank, and air necessary for biological treatment in the biological treatment tank. And an air supply unit for supplying water, a filtering unit for passing a part of wastewater from the biological treatment tank as treated water and returning the rest to at least the storage tank, and returning sludge from the biological treatment tank to the storage tank. A water treatment device comprising: a return means. 4. The water treatment apparatus according to claim 3, wherein the filtration means has a filtration membrane composed of a tubular ultrafiltration membrane or a tubular microfiltration membrane. 5. The water treatment apparatus according to claim 3, wherein the air supply means is configured to supply air by using an ejector and an opening / closing valve. 6. A storage tank for adjusting / uniformizing the amount and quality of wastewater, a biological treatment tank for biologically treating the wastewater from the storage tank, and air necessary for biological treatment in the biological treatment tank. And an air supply unit for supplying the air, the filtration unit being immersed in the waste water in the biological treatment tank, and a part of the waste water in the biological treatment tank passing as treated water to be discharged to the outside of the biological treatment tank, A water treatment device comprising: a return means for returning wastewater from the biological treatment tank to the storage tank. 7. The water treatment apparatus according to claim 6, wherein the filtration means has a filtration membrane constituted by an immersion type ultrafiltration membrane or an immersion type microfiltration membrane. 8. The water treatment device according to claim 1, further comprising an addition means for adding at least one of a coagulant and activated carbon to the waste water. 9. The water treatment apparatus according to claim 8, wherein ferric chloride or aluminum chloride is used as the coagulant. 10. The pH of the liquid inside the biological treatment tank is 5.8 to 10.
The water treatment device according to claim 1, wherein the water treatment device is controlled to 8.6. 11. The water treatment apparatus according to any one of claims 1 to 10, further comprising withdrawal means for withdrawing excess sludge in the storage tank.