JP3115705B2 - Aerobic biological sewage purification treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aerobic biological sewage purification method for purifying organic sewage containing BOD and SS in, for example, sewage, industrial wastewater, rivers, agricultural waterways, parks, playgrounds, and gardens. .

[0002]

2. Description of the Related Art In general, aerobic biological treatment methods known as one of effective methods for treating sewage include, for example,
As described in JP-B-63-66595, a filler for contacting microorganisms is provided to perform sewage treatment by aerobic organisms, and backflow washing is performed when the packed bed is blocked by sludge or the like. Processing methods are known.

[0003] Japanese Patent Publication No. 63-66595 discloses a method for filling microorganisms so that aerobic organisms in contact with the filler are peeled off by frequent backwashing and the purification capacity is not reduced. The increase in the water flow resistance, which indicates the resistance generated when sewage passes through the packed bed made of wood, is 1
When the pressure becomes 2 m-Aq or more, backflow cleaning is performed.

[0004]

However, in the method disclosed in Japanese Patent Publication No. 63-66595, the increase in water flow resistance, which indicates the resistance generated when sewage passes through the packed bed, is 1 to 5. Backflow cleaning is performed when the flow rate becomes 2 m-Aq or more.
The inflow of pollutants and increased microorganisms increases, and it is necessary to increase the flow rate of the backwash air and water and increase the cleaning time. As shown by the characteristic A in FIG. The residual water increases the initial water flow resistance, which is the water flow resistance after the operation of the purification treatment device and after the backflow cleaning, and shortens the purification treatment continuation time.
In addition, there is a problem that an excessively large apparatus is required because the upper portion of the packed bed requires at least 1 to 2 m or more.

It is an object of the present invention to provide an aerobic biological sewage purification method which can solve the above-mentioned conventional problems, can efficiently perform sewage purification treatment, and is effective in energy saving measures, and is economical. It is in.

[0006]

According to the method for purifying aerobic biological sewage of the present invention, an oxygen-containing gas is diffused into a packed bed made of a porous material for contacting microorganisms to aerobically fill the packed bed. The sewage is allowed to flow through the sewage while maintaining a static state, and the pollutants in the sewage are treated. The physical properties of the porous material are as follows: porosity is 35 to 45%, specific gravity is 1.4 to 2.1, and specific surface area. 1
000 to 100,000 cm ² / g, the porosity of the packed bed is 15 to 30%, and the increase of the water flow resistance value by the passage of the sewage is 0.5 to 0.7 m-Aq. At this point, the packed bed is washed.

[0007]

According to the aerobic biological sewage purification method of the present invention, the porosity is controlled to 35 to 45%, the specific gravity is controlled to 1.4 to 2.1, and the specific surface area is controlled to 10,000 to 100,000 cm ² / g. Microorganisms are present in or present in the porous portion of the porous material, and the porous material is used as a filler to reduce the porosity in the packed bed to 1%.
It is necessary for sewage treatment by filling so as to be 5 to 30%, and washing the packed bed when the increase in water flow resistance becomes 0.5 to 0.7 m-Aq due to the passage of sewage. Microorganisms are always kept without flowing out even in frequent backwashing with water and air, and there is no decrease in sewage treatment capacity. In addition, the pollutants and increased microorganisms flowing into the packed bed composed of the filler can be easily moved by backwashing because the specific gravity of the filler is small, so that the filler can easily move without being fixed to the surface of the filler. It can be peeled off and can easily flow out without remaining. Furthermore, since the specific gravity of the filler is small and the porosity of the packed bed is controlled to 15% or more, the initial water flow resistance, which is the water flow resistance at the initial stage of operation of the purification treatment device and after backwashing, can be reduced. When the water resistance value increases to 0.5 to 0.7 m-Aq, the backflow cleaning of the packed bed can be performed with low energy. From this, the sewage purification treatment continuation time becomes longer, and the sewage purification treatment by microorganisms can be performed stably and efficiently. Further, since backwashing is easy, the amount of air and water for backwashing can be reduced. . In addition, the packed bed also has a filtering action of sewage to be treated at the same time, so that treated water with good clarity can be obtained. Further, the filler has a porosity of 30% in the packed layer.
% Or less, the control of the particle size and the shape can be simplified, the manufacturing process can be performed by a simple method, and the yield can be improved to economically manufacture.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of an apparatus for carrying out the aerobic biological sewage purification method of the present invention will be described with reference to FIG.

Reference numeral 1 denotes a sewage tank.
Is provided with a pump 3 for transporting the wastewater 2. The pump 3 is connected to a sewage inflow pipe 6 communicating with an upper part of a treatment tank 5 provided with an on-off valve 4. The sewage 2 is formed at the upper part of the treatment tank 5 by the pump 3 via the sewage inflow pipe 6. Is supplied to the inflow section 7.

A packing layer 11 is provided in the processing tank 5, and the packing layer 11 is formed of a large number of fillers as porous materials.
The porosity, which is a gap between the fillers 12, is 1
It is formed so as to be filled to 5 to 30%.

The filler 12 is shown in FIGS.
As shown in (2), in order to sufficiently capture pollutants in the sewage water 2, the porous material is formed of a porous material having open pores 14 as a porous portion to which microorganisms 13 adhere, and this porous material has high strength and erosion. And a non-reactive ceramic, having a cylindrical shape with an average particle size of 6 mm, a porosity of 35 to 45%, and a specific gravity of 1.
4 to 2.1, specific surface area of 10,000 to 100,000
It is molded to be cm ² / g. The specific surface area is 45000 cm ² / g or more, and the sum of the porosity of the filling layer 11 and the porosity of the filling material 12, that is, the volume of the sewage 2 located in the filling layer 11 with respect to the volume of the filling layer 11. The ratio is 6
Preferably, it is controlled to be 0 to 70%.

The packed bed 11 has an outflow chamber 15 in the lower part.
Water-permeable supports 16 such as perforated tubes and perforated plates forming
Supported by

A water collecting and backwashing pipe 21 is provided in an outflow chamber 15 formed below the packed bed 11, and the water collecting and backwashing pipe 21 is connected to an outflow pipe 22. The on-off valve 23 is connected to. The on-off valve 23 and the outflow chamber
15 and the outflow pipe 22 has a backwash water supply pipe.
The backwash water supply pipe 24 is connected to a pump 26 provided in a treated / backwash water storage tank 25. A throttle valve 27 is connected in the middle of the backwash water supply pipe 24. Further, the throttle valve 27 is provided in parallel with the throttle valve 27.
A throttle valve 28 having a larger throttle amount is provided.

An outflow chamber 15 of the processing tank 5 is provided with an air diffuser 31 located above the water collecting and backwashing pipe 21. The air diffuser 31 includes a blower 32 having a blower 32. trachea
33 is connected. Further, the outflow chamber 15 of the processing tank 5 is provided with a backwash air supply pipe 36 to which a blower 35 is connected via an on-off valve 34.

On the other hand, a return port 41 for returning the sewage 2 located above the packed bed 11 is formed in the treatment tank 5, and the return port 41 has an open / close valve 42 having one end communicating with the sewage tank 1. Is connected to the return pipe 43.

The inflow section 7 of the processing tank 5 is provided with a recovery section 44 for recovering wastewater generated by backwashing. The recovery section 44 communicates with a concentration facility 46 through a backflow drainage pipe 45. Have been.

Next, the operation of this embodiment of the present invention will be described.

The on-off valve 4 of the sewage inflow pipe 6 is opened, and the pump 3
When the blower 32 connected to the air supply pipe 33 is driven, the sewage 2 flows from the sewage tank 1 through the sewage inflow pipe 6 into the inflow section 7 opened at the upper part of the treatment tank 5. The sewage 2 that has reached the inflow section 7 comes into contact with microorganisms 13 existing on the surface of the filler 12 that forms the filling layer 11 shown in FIG. 3, and pollutants in the sewage 2 are oxidatively decomposed.

The inside of the filling layer 11 is always maintained in an aerobic state. That is, an oxygen-containing gas such as air is sent from the air diffuser 31 by the blower 32 through the air supply pipe 33. In general, when air is used, 10 Nm ³ per kg of the removed BOD is sufficient when air is used, which is only 1/3 to 1/5 of that of the activated sludge treatment method. What is necessary is just to select and arrange in the position where the inside of the said filling layer 11 is maintained in an aerobic state.

The sewage 2 sufficiently purified in the packed bed 11 reaches a discharge chamber 15 as treated water via a water-permeable support 16 such as a perforated plate. The treated water in the outflow chamber 15 flows out through the outflow pipe 22 and the on-off valve 23 to the treated water / backwash water storage tank 25. Note that the treated water that has flowed into the treated water / backwash water storage tank 25 is introduced into another treatment step such as disinfection (not shown).

The above description is of the sewage treatment process. If this process is continued, the water flow resistance of the packed bed 11 gradually increases with the passage of the water flow time, and it becomes difficult to flow water. Therefore, before water flow becomes difficult, specifically, the packed bed 11
The water flow rate (L
V) The water flow resistance of 15 m / h or less and BOD volume load of 5 kg / m ³ .d or less will increase the water flow resistance by 0.5 to 0.7.
A washing step is performed each time the m-Aq is reached. The increase in the water flow resistance is detected by a detection unit (not shown) such as a water level detection unit provided in the inflow section 7 above the treatment tank 5. Then, the control unit (not shown) detects the signal of the detection unit so as to control the following cleaning process. Further, instead of the detecting means, the following cleaning step can be controlled by a timer or the like before the increase in the water flow resistance becomes 0.5 to 0.7 m-Aq.

In this washing step, the on-off valve 4 provided on the sewage inflow pipe 6 is closed, the pump 3 is stopped, the on-off valve 23 is closed, and the on-off valve 42 of the return pipe 43 is opened for about 2 to 3 minutes.
From 43, the sewage 2 stored in the packed bed 11 is returned to the sewage tank 1. After the water level in the processing tank 5 reaches the return port 41 which is opened by connecting the return pipe 43, backflow cleaning with air is performed. That is, open the on-off valve 34 of the backwash air supply pipe 36 for about 5 minutes,
Drives the blower 35 and fills the air from the backwash air supply pipe 36
Backflow cleaning is performed by ejecting the air at a flow rate of about 1 m ³ / m ² / minute into the inside of the chamber 11.

Further, the throttle valve 28 is opened and the pump 26
A part of the water in the treated water / backflow washing water storage tank 25 is jetted out of the water collection / backflow washing pipe 21 for about 1 minute to perform the air / water backflow washing. This backwashing uses air at a rate of about 1 m ³ / m ² / min and water at a rate of about 0.5 m ³ / m ² / min.

Next, the blower 35 is stopped and the throttle valve is stopped.
28 is closed, the throttle valve 27 is opened, and the water in the treated water / backwash water storage tank 25 is spouted from the collection / backwash water pipe 21 by the pump 26 at about 1 m ³ / m ² / minute for about 3 minutes. Perform water backwash.

After completion of the backwash, the pump 26
Is stopped, and the throttle valve 27 is closed and allowed to stand for 1 to 2 minutes. The wastewater generated by this water backwashing flows from the recovery unit 44 through the backwashing drainage pipe 45 to the concentration equipment 46. Further, the drainage remaining in the inflow portion 7 of the treatment tank 5 is returned to the wastewater tank 1 by opening the on-off valve 42, and the washing step is completed.

Next, a sewage treatment step is continuously performed.

Next, the operation of the above embodiment will be described.

In experiments conducted by the present inventors, the packed bed 11
Various kinds of clays were blended with the main raw material of the filler 12 to form, and various samples were molded into cylindrical pellets in consideration of moldability and manufacturability, and various experiments were performed.

The porosity and the specific gravity were measured according to JIS-R-2.
The specific surface area was measured by an apparent porosity and an apparent specific gravity based on No. 205, and the specific surface area was measured by a nitrogen adsorption method. Also,
The porosity is calculated from the ratio occupied by the filler from the apparent specific gravity with respect to the volume filled by tap filling, and the sum of the porosity of the filler layer 11 and the porosity of the filler 12, that is, the volume of the filler layer 11 The ratio of the volume of the wastewater 2 located in the packed bed 11 to the volume of the wastewater 2 was measured by a pycnometer method.

First, a packed bed 11 was formed from samples having the same composition and different particle sizes, and as a result of comparing and examining the initial water flow resistance and the power consumption of a pump, a blower, and the like at the time of backflow cleaning,
As shown in FIGS. 4 and 5, as the particle diameter increases, the initial water flow resistance decreases, and the wastewater can be efficiently treated.
Conversely, large energy is required for backwashing.
Therefore, the filler was molded so as to have a particle size of 6 mm in consideration of moldability and manufacturability.

As shown in FIG. 6, when the porosity increases, that is, when the number of open pores increases, the amount of microorganisms existing in the open pores increases. In addition, since this microorganism is proportional to the treatment capacity of sewage, it is understood that the treatment capacity increases as the porosity increases. Moreover, the abundance of this microorganism is also proportional to the specific surface area. However, if the porosity is 10
%, When forming a sample so as to be less than or equal to%, the clay particles of the raw material must be molded at a high pressure using a fine particle powder having a narrow particle size distribution, and the moldability and manufacturability are very poor, Yield also declined. In addition, when the sample is manufactured by controlling the porosity to 60% or more, the strength of the sample is remarkably reduced, and the sample is easily damaged by stress such as transport and backwashing.
It is determined that the filler 12 cannot be used. In addition, the result of the porosity was proportional to the result of an experiment performed on the specific surface area at the same time.

On the other hand, as a result of measuring the power consumption at the time of backflow washing while changing the apparent specific gravity, as shown in FIG. 7, when the specific gravity is set to 1.5, the specific gravity is about 2.2, and the doubled energy is obtained. It turns out that it is necessary. Then, the specific gravity is 2.1 or less, which is a value lower than the initial water flow resistance at the initial stage of the conventional apparatus operation.
In addition, when the specific gravity was 1.3, the sample filled in the packed bed floated, and sewage treatment could not be performed.

The particle size and shape are changed so that the porosity is different by using a sample molded by controlling the apparent porosity to 35%, the apparent specific gravity to 1.5, and the specific surface area to 60,000 cm ² / g as a filler. As a result of measuring the initial water flow resistance after forming the packed layer, as shown in FIG. 8, when the porosity is 10%, as the water flow time of the sewage water 2 elapses, the initial flow resistance after the backflow cleaning is increased. Water resistance rises. However, when the filling was performed so that the porosity was 15% or more, the initial water resistance was substantially constant even after the passage of water, and there was no large difference in the initial water resistance when the porosity was 30% or more. The porosity of a sample molded into a sphere or a cylinder can be easily controlled to 15% to 30%, and it can be determined that a sphere or a cylinder is preferable from the viewpoint of moldability and manufacturability.

From the above experiments, it was found that the filler 12 had a cylindrical shape with an average particle diameter of 6 mm, an average apparent porosity of 40%, an average apparent specific gravity of 1.5, and an average specific surface area of 60,000 cm ^2.
/ G, and the filler 12 has a porosity of 20
%, And the packed layer 11 has a cross-sectional area of 0.5 m
^2. An experiment was conducted using an experimental processing apparatus formed so as to have a volume of 1 m ^{3 in} comparison with the conventional processing method.

The results of this experiment show that the change over time in the initial resistance to water flow with the conventional aerobic biological purification method for forming a microbial contact filler is A, and that with the purification method of the present invention is A. B, and the vertical axis shows the initial water resistance (unit is
m-Aq), and the horizontal axis represents water passage time (unit: months), and is shown in FIG.

According to the conventional sewage purification method, the initial water flow resistance value, as shown by the characteristic A, keeps a constant high value after continuing to rise for a certain period of time. According to the treatment method, as shown in the characteristic B, there is no difference between the initial water flow resistance value at the beginning of the operation and the initial water flow resistance value one year later, and the microorganisms required for the sewage purification treatment are secured by backwashing. It is determined that the remaining microorganisms and pollutants in the sewage that have multiplied are surely removed from the treatment tank. Further, in the conventional method, the number of times of the backflow cleaning increases as the initial water flow resistance value increases. However, in this embodiment, once or twice a day even after one year has passed.
The contaminants in the sewage water 2 and the residual microorganisms that grew in the sewage water 2 could be removed by a single backwash.

From the above experiments, the filler 12 was cylindrical with an average particle diameter of 6 mm, had a porosity of 35 to 45%, a specific gravity of 1.4 to 2.1, and a specific surface area of 10,000 to 100, 0
Molded so that 00cm ² / g, by forming the filling layer 11 is filled with the filling material 12 as the porosity of 15% to 30%, it can be produced easily and economically filler It is determined that the wastewater 2 can be efficiently and economically treated by maintaining the initial water flow resistance in a low state.

According to the above embodiment, the porosity is 35 to 45.
%, Specific gravity 1.4-2.1, specific surface area 10,000-
Filling material 12 made of a porous material for contacting microorganisms, which is controlled to 100,000 cm ² / g, is filled so that the porosity, which is the space between the filling materials 12, is 15 to 30%. Form. Then, air, which is an oxygen-containing gas, is diffused into the packed layer 11 to pass through the sewage 2 and treat pollutants in the sewage 2 while maintaining the inside of the packed layer 11 in an aerobic state. The packed bed 11 was treated so that the packed bed 11 was periodically cleaned every time the increase in the water flow resistance value became 0.5 to 0.7 m-Aq due to the passage of the sewage 2.

Accordingly, in the porous material filled in the packed bed in the conventional sewage treatment method, the specific gravity of the porous material is large, so that a large amount of energy for backflow cleaning, that is, a large amount of water and air is treated at a high flow rate. Although it is necessary to squirt into the tank, by using a porous material having a small specific gravity as the filler 12 as in the treatment method of the present invention, in backwashing,
Backwashing is possible under the condition of low backwashing energy of 1 m ³ / m ² / min, and under these conditions, pollutants in the sewage water 2 and the remaining microorganisms that have multiplied can be removed from the treatment tank 5 reliably. Backwashing can be appropriately performed, and clogging by sludge can be prevented, and bulking does not occur.
Can be processed without circulating sludge or water. And
Only a small amount of water and air is used for backwashing, and furthermore, the ejection energy required for backwashing can be reduced, which is economical.

The filler 12 for contacting microorganisms has a porosity of 35 to 45%, a specific gravity of 1.4 to 2.1, and a specific surface area of 1 to 1.
By using the porous material controlled to 000 to 100,000 cm ² / g, the microorganisms 13 adhering to the open pores 14 which are the porous portions are not peeled off by the backwashing, and sufficient treatment is performed after the backwashing. Capability is maintained, and stable biological treatment becomes possible.

Further, the initial water flow resistance value at the beginning of the operation can be maintained for a long time, the initial water flow resistance value is stabilized, and the purification time of the waste water 2 can be efficiently performed by increasing the duration of the purification processing of the waste water 2. .

In addition, the clarity of the treated water is good due to the filtering action, and the sedimentation / separation section is not required, and the apparatus can be downsized.

Further, not only BOD removal but also NH ₄ ⁺ -N
N 2 also acts on sewage 2 containing N
H ₄ ⁺ -N can be removed, and the cost of treating wastewater 2 can be greatly reduced.

In the above embodiment, the filler 12 is formed by extruding ceramics, which is described as being extruded. However, the porosity is 35 to 45% and the specific gravity is increased, for example, when sand or the like is granulated with a synthetic resin or the like. Any porous material having a specific surface area of 1.4 to 2.1 and a specific surface area of 10,000 to 100,000 cm ² / g can be used.

Further, the outflow chamber 15 is provided in the treatment tank 5, and the outflow chamber 15 is provided with the water collecting / backflow cleaning pipe 21, the backflow air supply pipe 36, and the diffuser 31. The water collecting and backwashing pipe 21, the backwashing air supply pipe 36, and the air diffuser 31 may be disposed below the packed bed 11 so as to be buried. Further, the backwash air supply pipe 36 and the diffuser 31 may be integrated into one.

[0046]

According to the aerobic biological sewage purification method of the present invention, the porosity is 35 to 45% and the specific gravity is 1.4 to 2.
1. Specific surface area of 10,000 to 100,000 cm ² / g
Microorganisms are allowed to exist or exist in the porous portion of the porous material controlled as described above, and this porous material is used as a filler to fill the packed bed so that the porosity is 15 to 30%, and the passage of sewage is performed. 0.5-0.7m-Aq
By washing the packed bed at the point of time, microorganisms required for sewage treatment are always secured without flowing out even in frequent backwashing with water and air, and there is no decrease in sewage treatment capacity. Further, the pollutants and the increased microorganisms flowing into the packed bed composed of the filler, because the specific gravity of the filler is small, the filler can be easily moved by backwashing,
It can be easily peeled off without sticking to the filler surface, and can easily flow out without remaining. Furthermore, since the specific gravity of the filler is small and the porosity of the packed bed is controlled to 15% or more, the initial water flow resistance, which is the water flow resistance at the initial operation of the purification treatment device and after the backflow cleaning, can be kept low. When the water resistance value increases to 0.5 to 0.7 m-Aq, the backflow cleaning of the packed bed can be performed with low energy.
From this, the duration of the sewage purification process becomes longer, and the sewage purification process by microorganisms can be performed stably and efficiently. Further, since the backwashing is easy, the amount of air and water for the backwashing can be reduced. . In addition, the packed bed also has a filtering action of sewage to be treated at the same time, so that treated water with good clarity can be obtained. Further, the filler can be manufactured in a simple method by simplifying the control of the particle size and shape by setting the porosity of the filler layer to 30% or less, and
Yield is improved and it can be manufactured economically.

[Brief description of the drawings]

FIG. 1 is a system explanatory diagram showing a configuration of an embodiment of an apparatus for performing an aerobic biological sewage purification treatment method of the present invention.

FIG. 2 is a diagram showing a filler of a porous material for contacting microorganisms, which forms a packed layer provided in a treatment tank forming an apparatus for performing the purification treatment method of the present invention.

FIG. 3 is an enlarged cross-sectional view of the filler showing the state of attachment of microorganisms to the filler.

FIG. 4 is a graph showing changes in initial water flow resistance due to different particle diameters of the filler when a filler layer is formed with the above various fillers.

FIG. 5 is a graph showing a change in a backflow cleaning energy ratio due to different particle sizes of the filler when a filler layer is formed with the above various fillers.

FIG. 6 is a graph showing changes in the ratio of the amount of microorganisms present in open pores due to different apparent porosity of the filler when a filler layer is formed with the various fillers.

FIG. 7 is a graph showing changes in the backflow cleaning energy ratio due to different apparent specific gravities of the filler when a filler layer is formed with the above various fillers.

FIG. 8 is a graph showing changes over time in initial water flow resistance when the filling layers are formed with different porosity using the same various filling materials.

FIG. 9 is a graph showing changes over time in initial water flow resistance according to the conventional method and the method of the present invention.

[Explanation of symbols]

 2 Wastewater 5 Treatment tank 11 Packing layer 12 Filler as porous material 21 Water collecting and backwashing pipe 31 Aerator

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-46-2584 (JP, A) JP-A-1-148395 (JP, A) JP-A-56-113393 (JP, A) JP-A 5- 208200 (JP, A) Japanese Utility Model 3-115098 (JP, U) JP-B-63-66595 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) C02F 3/06 C02F 3 /Ten

Claims (1)

(57) [Claims] An oxygen-containing gas is diffused into a packed bed made of a porous material for contacting microorganisms, and while the inside of the packed bed is maintained in an aerobic state, sewage is allowed to flow through the packed bed, thereby causing pollutants in the sewage. And treating the physical properties of the porous material with a porosity of 35 to 45.
%, Specific gravity 1.4-2.1, specific surface area 10,000-
100,000 cm ² / g, and the porosity of the packed bed is 15 to 30%.
An aerobic biological sewage purification method, wherein the packed bed is washed when the pressure reaches 0.7 m-Aq.