JPH0810764A - Sewage treatment - Google Patents

Abstract

PURPOSE:To reduce a running cost and equipment cost of sewage treatment by filtering sewage with a filtering means formed with thin-film layers of a metal hydroxide on its surfaces by a water head pressure and peeling the thin-film layers together with contaminating materials when the water pass rate of the filtering means decreases, then forming the thin-film layers again on the surfaces of the filtering means. CONSTITUTION:A slurry 21 previously suspended with the metal hydroxide and non- compressive material is admitted into a filter tank 7 and is filtered and separated on the surfaces of a water permeable sheet 11 by the water head pressure at the time of the sewage treatment. The treated water 13 in a reflux tank 15 is thereafter admitted into the filter tank 7 and the non-compressive material is filtered and separated on the surfaces of the water permeable sheet 11, by which the thin-film layers of the metal hydroxide are formed thereon. The sewage 2 is admitted in this state and the treated water 13 is discharged into the reflux tank 15 and is released from a releasing pipe. the treated water 13 in the reflux tank 15 is sent to a filter body 10, where the thin-film layers are peeled together with the captured contaminating materials and are discharged outside the tank. The thin-film layers of the metal oxide are thereafter formed again on the surfaces of the water permeable sheet 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewage treatment method for further advanced treatment of secondary treated water treated in, for example, an activated sludge aeration tank or a contact aeration tank.

[0002]

2. Description of the Related Art Conventionally, as a sewage treatment method for further highly treating secondary treated water treated in, for example, an activated sludge aeration tank or a contact aeration tank, coagulation sedimentation, coagulation filtration, ultrafiltration membrane of the secondary treated water is used. There is known a method of processing by means of membrane separation or the like.

[0003]

However, the above
In the conventional method of treating by coagulating contaminants such as coagulating sedimentation and coagulating filtration, it is necessary to control the amount of flocculant added and the floc formation state by using a coagulant depending on the polluted state of wastewater. In addition, the cost is increased and the sewage treatment operation is complicated.

On the other hand, in the method of membrane separation using an ultrafiltration membrane or the like, the membrane is expensive and sewage must be filtered by applying pressure with a pump or the like, which increases the operating cost and the membrane is expensive. There is a problem that equipment cost increases because a device such as a pump for generating pressure is required.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a sewage treatment method capable of easily treating sewage at a low cost with a simple structure.

[0006]

According to a first aspect of the present invention, there is provided a sewage treatment method comprising: a filtration tank into which sewage is introduced; and a filter which is hollowed out by a water-permeable sheet and is immersed in the sewage water in the filtration tank. Means, an outflow pipe connected to the filtering means for flowing out the treated water filtered in the filtering means by the head pressure of the wastewater to the outside of the filtration tank, and a metal hydroxide that cannot pass through the surface of the water-permeable sheet. And a metal hydroxide thin film layer through which the sewage formed of a substance can pass, and the sewage flowing into the filtration tank is filtered by the filtration means by the head pressure of the sewage, and the reduction of the water flow rate of the filtration means causes the When the water level of the sewage in the filtration tank rises, the metal hydroxide thin film layer is peeled off, and the metal hydroxide thin film layer is formed again on the surface of the filtering means.

The wastewater treatment method according to claim 2 is the method according to claim 1.
In the sewage treatment method described above, a slurry containing a metal hydroxide that cannot pass through a water-permeable sheet is filtered by a head pressure of the slurry by a filtration means to allow the metal hydroxide to be carried on the surface of the water-permeable sheet. To form a metal hydroxide thin film layer.

[0008]

In the method for treating sewage according to claim 1, the sewage head pressure of the sewage flowing into the filtration tank causes the filtration means immersed in the filtration tank to filter the water. When the water level of the sewage rises, the metal hydroxide thin film layer is peeled off together with the pollutants of the filtered sewage, and the metal hydroxide thin film layer is formed again on the surface of the filtering means.
Since it does not require an expensive membrane or a pump to pump the sewage in order to perform membrane filtration, the head pressure is used for filtration, which reduces operating and equipment costs and reduces the water flow rate of the filtration means by reducing the level of sewage in the filtration tank. Therefore, the wastewater treatment operation is easy, and the water flow rate of the filtering means can be maintained only by forming and peeling the metal hydroxide thin film layer, which facilitates maintenance management.

The wastewater treatment method according to claim 2 is the method according to claim 1.
In the sewage treatment method described, the metal hydroxide is carried on the surface of the water-permeable sheet by filtering the slurry containing the metal hydroxide that cannot pass through the water-permeable sheet by the head pressure of the slurry in the filtering means. An inexpensive water-permeable sheet that facilitates the formation of a metal hydroxide thin film layer that allows filtration and adsorption separation of contaminants such as suspended solids, phosphate ions, and color-forming substances in wastewater because a metal hydroxide thin film layer is formed. However, it becomes possible to filter and adsorb floating substances, phosphate ions, coloring substances, etc. in wastewater.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of an embodiment of an apparatus for carrying out the wastewater treatment method of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a raw water tank, and the raw water tank 1 stores secondary treated water treated as, for example, an aeration tank for activated sludge or a contact aeration tank as waste water 2.
Then, in the raw water tank 1, a sewage pipe 4 for flowing the sewage 2 out of the raw water tank 1 via a sewage valve 3 such as a valve or a solenoid valve.
Is provided. Further, the waste water pipe 4 has a waste water 2
Is provided with a pump 6 which is connected to an inflow pipe 8 whose end opens to the upper part of the filtration tank 7.

A filter body 10 as a filtering means is arranged in the filter tank 7. The filter body 10 has, for example, two water-permeable sheets 11 made of non-woven fabric or woven cloth having a minimum retention particle diameter of 10 μm to 100 μm, and a water-permeable porous material 12 such as a sponge for holding a gap. Or water-permeable sheet 11,
The periphery is sealed at 11 to form a hollow bag. The filter body 10 has a shape and an arrangement in the filter tank 7 depending on the polluted state of the sewage 2, that is, the contained state of phosphate ions, various metal ions, coloring substances, organic or inorganic floating substances, soluble organic substances, and the like. The number, the minimum retained particle diameter of the water-permeable sheet 11 and the material thereof are set.

An outlet pipe 14 for connecting the treated water 13 filtered inside to the outside of the filter tank 7 is connected to the filter body 10. The outflow pipe 14 is provided so that the dirty water 2 that has flowed into the filtration tank 7 is filtered by the filter body 10 by the head pressure.

Further, the outflow pipe 14 is provided with a reflux tank 15 for storing the treated water 13, and the reflux tank 15 is provided with a reflux valve 16 such as a valve or an electromagnetic valve and is connected to the pump 6. A pipe 17 is provided, and the treated water 13 to be stored is made to flow into the filtration tank 7 again from the inflow pipe 8 by the pump 6.

Further, the reflux tank 15 is provided with a discharge pipe provided with a discharge valve such as a valve or a solenoid valve (not shown) for discharging the treated water 13 that has been treated.

On the other hand, 20 is a slurry tank, and this slurry tank 20
In addition, the slurry 21 separately prepared by suspending and mixing metal hydroxide in water or the like at a predetermined concentration is stored. The slurry tank 20 is provided with a slurry valve 22 such as a valve and a solenoid valve, and a slurry pipe 23 connected to the pump 6.

The slurry 21 is formed by appropriately mixing and suspending incompressible substances such as diatomaceous earth and calcium carbonate fine powder in addition to the metal hydroxide depending on the polluted state of the sewage 2 to be treated. Further, as the metal hydroxide, various metal hydroxides are appropriately selected depending on the contamination state of the sewage 2 to be treated, and not only one kind but also a plurality of kinds may be mixed and used. It is set according to the minimum retained particle size of 1 and the contamination state of the sewage 2.

Further, in the outflow pipe 14, the air and the treated water 13 in the reflux tank 15 are caused to flow back to the filter body 10 so that the water-permeable sheets 11, 11 are formed.
Backwashing as a peeling means (not shown) for peeling metal hydroxide adhering to the surface of water, phosphate ions in sewage 2, various metal ions, coloring substances, organic or inorganic suspended substances, soluble organic substances, etc. A device is provided.

As the peeling means, it is provided at the bottom of the filter tank 7 below the filter body 10 to aerate air so that metal hydroxides or contaminants adhering to the surface of the water-permeable sheet of the filter body 10 are contaminated. An aeration device for peeling substances, a device that lifts the filter body 10 above the filtration tank 7 with a crane, and mechanically peels it by scratching it with a jet water stream, a brush, a chelate, or the like, peeling with ultrasonic waves or vibrations. Any structure such as a device for causing the change can be used.

Next, a method for treating sewage using the apparatus of the above embodiment will be described.

First, a slurry 21 prepared by separately suspending a metal hydroxide and an incompressible substance such as diatomaceous earth and calcium carbonate fine powder is poured into a slurry tank 20 and stored therein. Then, the slurry valve 22 is opened and the pump 6 is driven to allow a small amount of the predetermined amount of the slurry 21 to flow into the filtration tank 7. Due to the inflow of the slurry 21, non-compressible substances such as metal hydroxide in the slurry 21 and diatomaceous earth or calcium carbonate fine powder, which are appropriately suspended and mixed, are mixed with each other in the height of the water surface of the slurry 21 in the filtration tank 7 and filtered. The water head pressure generated due to the water head difference from the height of the outflow pipe 14 connected to the body 10 causes the surface of the water permeable sheet 11 to be separated by filtration. Further, the filtrate filtered in the filter body 10 flows into the reflux tank 15 via the outflow pipe 14.

After the slurry 21 flows in, the slurry valve 22 is closed and the reflux valve 16 is opened to treat the treated water in the reflux tank 15.
13 and the filtrate are flown into the filtration tank 7 from the inflow pipe 8 through the reflux pipe 17 and are refluxed for a predetermined time, for example, about 5 to 30 minutes. By this reflux, the incompressible substance such as metal hydroxide, appropriately suspended and mixed diatomaceous earth, calcium carbonate fine powder, etc. is generated by the head pressure of the mixed liquid of the slurry 21 and the treated water 13 and the filtrate in the filtration tank 7. Is filtered and separated on the surface of the water-permeable sheet 11 to form a thin metal hydroxide thin film layer.

The flow rate of the slurry 21 into the filtration tank 7 is
The metal hydroxide thin film layer is allowed to flow so as to have a thickness of about 0.3 to 1 mm. In addition, even if some incompressible substances such as metal hydroxide and diatomaceous earth or calcium carbonate fine powder mixed appropriately in suspension flow into the reflux tank 15 without being filtered, metal hydroxide that grows by reflux Slurry filtered by a thin film layer
Non-compressible substances such as all metal hydroxides in 21 and diatomaceous earth and calcium carbonate fine powder, which are appropriately suspended and mixed, are formed in the metal hydroxide thin film layer.

The metal hydroxide thin film layer is constantly formed on the surface of the water-permeable sheet 11 because the head pressure is constantly applied by reflux.

By this reflux, all incompressible substances such as metal hydroxide and diatomaceous earth or calcium carbonate fine powder which are appropriately suspended and mixed are formed as a metal hydroxide thin film layer, and the mixed solution in the filtration tank 7 is formed. When the water becomes transparent, the reflux valve 16 is closed and the sewage valve 3 is opened to remove the sewage 2 in the raw water tank 1.
Depending on the polluted state of the sewage, the sewage is allowed to flow into the filtration tank 7 at a rate of, for example, 1 to 1000 m ³ / day so that a predetermined head pressure is obtained.

By the inflow of the sewage 2, the suspended substances in the sewage 2 are filtered into the metal hydroxide thin film layer, and the phosphate ions and various metal ions in the sewage 2 form the metal hydroxide thin film layer. Adsorbed on metal hydroxide. In addition, soluble organic substances in the wastewater 2 were filtered into the metal hydroxide thin film layer by non-compressible substances such as diatomaceous earth and calcium carbonate fine powder constituting the metal hydroxide thin film layer. An organic suspended substance forms an activated sludge thin film layer on the surface of the metal hydroxide thin film layer, and is decomposed by this activated sludge thin film layer. In this process, oxygen may be appropriately aerated to supply oxygen to the activated sludge thin film layer.

Then, the treated water 13 filtered by the filter body 10
Is flown into the reflux tank 15 through the outflow pipe 14, opens a discharge valve (not shown), and discharges it from the discharge pipe.

By continuing the treatment of the sewage 2,
The inflow amount of the sewage 2 becomes larger than the outflow amount of the treated water 13 discharged from the outflow pipe 14 to the reflux tank 15 due to the filtration of the sewage 2, and the constant water surface position of the sewage 2 in the filtration tank 7 gradually increases. In this case, it is determined that the filtered water on the surface of the metal hydroxide thin film lowers the water flow rate and the treatment capacity, and closes the sewage valve 3 and the discharge valve (not shown) and stops the pump 6. Then, the remaining sewage 2 in the filtration tank 7
Let stand until the head pressure drops and filtration becomes impossible.

The pump 6 is stopped to filter the sewage 2 in the filtration tank 7 and the head pressure of the sewage 2 in the filtration tank 7 disappears, whereby the metal hydroxide formed on the surface of the water-permeable sheet 11 is discharged. The thin film layer is easily peeled off.

Then, when the head pressure of the waste water 2 in the filtration tank 7 disappears and the treated water 13 does not flow into the reflux tank 15, the treated water in the reflux tank 15 is removed by a backflow cleaning device (not shown).
13 and air are sent to the filter body 10, the metal hydroxide thin film layer formed on the surface of the water-permeable sheet 11 and the pollutants in the filtered wastewater 2 are peeled off and discharged to the outside of the filtration tank 7 for treatment.

After that, the metal hydroxide thin film layer is again formed on the surface of the water permeable sheet 11 and the treatment of the sewage 2 is repeated.

When the polluted state of the wastewater 2 is low, the wastewater 2 may be directly filtered with only the water-permeable sheet without forming the metal hydroxide thin film tank.

In the above embodiment, the slurry 21 containing the metal hydroxide is filtered by the head pressure of the slurry 21 in the filter body 10 in which the slurry 21 is immersed in the filter tank 7 to filter the metal hydroxide into the water-permeable sheet of the filter body 10. After forming a metal hydroxide thin film layer on the surface of 11 to form a metal hydroxide thin film layer, sewage 2 is allowed to flow into the filtration tank 7, and the metal hydroxide thin film layer is formed on the surface by the head pressure of sewage 2. The wastewater 2 is filtered by the filter body 10 to be formed, and when the water level of the wastewater 2 in the filtration tank 7 rises due to a decrease in the water flow rate of the filter body 10, the metal hydroxide thin film layer is filtered by the backwashing device. The metal hydroxide is peeled off together with the pollutants of the wastewater, and a metal hydroxide thin film layer is again formed on the surface of the water-permeable sheet 11 of the filter body 10.

Therefore, there is no need for a pump for pumping sewage to the membrane for membrane filtration, and sewage 2 can be treated at a high level without using an expensive microfiltration membrane or ultrafiltration membrane. Can be reduced. Further, since the decrease in the water flow rate of the filter body 10 is judged by the water level of the sewage 2 in the filtration tank 7, the treatment operation of the sewage 2 is easy, and the optimum filtration of the filter body 10 forming the metal hydroxide thin film layer is performed. The wastewater 2 can be treated in the state, and the wastewater 2 can be efficiently treated.

Further, the metal hydroxide thin film layer can be stably formed on the surface of the water-permeable sheet 11 by the water head pressure, and at the time of peeling, the water head pressure is released and peeling is performed by backwashing.
The metal hydroxide thin film layer can be easily formed and peeled, and the water permeability of the filter body 10 can be maintained only by forming and peeling the metal hydroxide thin film layer, and maintenance can be facilitated.

Further, on the surface of the water-permeable sheet 11, contaminants such as fine floating substances, phosphate ions and color-forming substances in the wastewater 2 can be filtered, and a metal hydroxide capable of being adsorbed and separated into a thin film. In order to form, for example, an inexpensive water-permeable sheet 11 such as a non-woven fabric or a woven fabric can filter and adsorb floating substances, phosphate ions, color-forming substances and the like in the wastewater 2, and depending on the state of the wastewater 2, the type of metal hydroxide. By appropriately setting the particle size, the particle size, and the thickness of the metal hydroxide thin film layer, any sewage 2 can be treated, and the sewage 2 can be treated easily at low cost.

Further, depending on the polluted state of the sewage 2, it is possible to directly perform the filtration treatment with the water-permeable sheet 11 without forming the metal hydroxide thin film layer, and the sewage 2 can be dealt with the polluted state.
Versatility can be improved.

In the above embodiments, the secondary treated water treated in the activated sludge aeration tank or the contact aeration tank was treated as the sewage 2, but the water of rivers, lakes, irrigation channels, dams, etc. was highly treated. It can also be used for processing.

[0039]

According to the sewage treatment method of claim 1,
The wastewater is filtered by the head pressure of the wastewater by the filtration means, and when the water level of the wastewater rises due to the decrease in the water flow rate of the filtration means, the metal hydroxide thin film layer is peeled off together with the pollutants of the filtered wastewater and filtered again. Since the metal hydroxide thin film layer is formed on the surface of the means, it is possible to reduce the operating cost and the equipment cost because it does not require an expensive membrane or a pump to pump wastewater to perform membrane filtration, and the head pressure is used for filtration. Since the decrease in the water flow rate of the filtration means is judged by the water level of the waste water in the filtration tank, the operation of treating the waste water is easy and the water flow rate of the filtration means can be maintained only by forming and peeling the metal hydroxide thin film layer. Easy maintenance management.

According to the sewage treatment method of the second aspect, in the sewage treatment method of the first aspect, the slurry containing the metal hydroxide is filtered by the head pressure of the slurry by the filtering means to obtain the metal hydroxide. Since a metal hydroxide thin film layer is formed by supporting it on the surface of a water-permeable sheet, it is easy to form a metal hydroxide thin film layer that can filter and adsorb and separate contaminants such as floating substances, phosphate ions, and coloring substances in wastewater. It is possible to easily form and form an inexpensive water-permeable sheet to easily filter and adsorb pollutants in wastewater.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an apparatus for carrying out the wastewater treatment method of the present invention.

[Explanation of symbols]

 2 Sewage 7 Filtration tank 10 Filtration body as filtration means 11 Water-permeable sheet 13 Treated water 14 Outflow pipe 21 Slurry

Claims (2)

[Claims] 1. A filtration tank into which sewage is introduced, a filtering means which is hollow in a water-permeable sheet and immersed in the sewage water in the filtration tank, and a head pressure of the sewage connected to the filtration means. An outflow pipe for flowing out the treated water filtered in the filtering means to the outside of the filtration tank, and a metal through which the sewage formed by an impermeable metal hydroxide on the surface of the water permeable sheet can pass. A hydroxide thin film layer is provided, and when the wastewater flowing into the filtration tank is filtered by the above-mentioned filtration means by the above-mentioned filtration means, and when the water level of the above-mentioned wastewater in the above-mentioned filtration tank rises due to the reduction of the water flow rate of the filtration means, the Peel off the oxide thin film layer,
A sewage treatment method comprising forming a metal hydroxide thin film layer on the surface of the filtering means again. 2. A metal hydroxide containing a metal hydroxide that cannot pass through a water-permeable sheet is filtered by a head pressure of the slurry by a filtering means to support the metal hydroxide on the surface of the water-permeable sheet. The sewage treatment method according to claim 1, wherein a hydroxide thin film layer is formed.