JPH0720587B2 - Filter media circulation type wastewater purification method and device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improved method for purifying wastewater using a filter medium and an apparatus therefor.

[Background technology]

The method of purifying wastewater using filter media involves placing a large number of filter media in a septic tank to form a filter bed, which is an assembly of filter media, and purifying the wastewater using aerobic or anaerobic bacteria propagated in this filter bed.There are two types of methods: aerobic and anaerobic.

However, this method of purifying wastewater has the problem of clogging of the filter media or filter bed with sludge, which reduces the purification capacity. In this specification, "sludge" refers to various solids separated from wastewater.

Conventional methods for preventing clogging include modifying the filter material itself to make it less susceptible to clogging, or treating wastewater that has been pre-purified to a certain extent to reduce its concentration.

However, the preliminary purification method itself is quite troublesome, and even if preliminary purification is performed, it can only delay the progression of clogging, but it is impossible to prevent clogging itself, so in the end, there is no choice but to periodically clean or replace the filter media, which is a very difficult task.

In addition, the filter material itself has also been invented, for example, in Japanese Patent No. 1343032
Although it is possible to obtain a filter medium with a fairly high clogging prevention effect, such as the spherical filter medium in Patent Publication No. 2440 of 1986, which is floating and does not easily become entangled, in the end, it is insufficient to prevent clogging itself.

This invention was made against the background of the above-mentioned conventional circumstances, and aims to provide a method and apparatus for purifying wastewater that can effectively prevent clogging of the filter material itself and always enables efficient purification.

DISCLOSURE OF THE INVENTION

This objective is achieved by a filter medium circulation type wastewater purification method in which a passage for circulating filter medium is partitioned and formed within a septic tank, a water flow is formed within this circulation passage using a water flow forming means, and the filter medium is moved in a circulatory manner by this water flow.

This method is based on the knowledge that if filter material is always moving, it can effectively prevent clogging, but on the other hand, if filter material is simply moved randomly, the sludge that separates from filter material will be scattered in the septic tank due to this random movement, and this will cause the purification efficiency to decrease.In other words, the method of this invention as described above is to achieve the constant and orderly movement of filter material that is required by the knowledge as described above, so that it can effectively prevent filter material from clogging, and always enable efficient purification.

Such a method is realized by a filter medium circulation type wastewater purification device in which a passage for circulating filter medium is partitioned and formed within a septic tank, and a water flow forming means is provided at one end of this circulation passage.

In carrying out the above method, it is possible to partition and form a circulation passage in the vertical direction using a cylindrical body that is open at the top and bottom. This method has the advantage that the sludge is peeled off from the filter material in the circulation passage during movement, and the peeled sludge can be easily disposed of. This method
This is realized by a filter media circulation type wastewater purification device that uses a cylindrical body that is open at the top and bottom to divide and form circulation passages in the vertical direction, and also by a filter media circulation type wastewater purification device that has a pit for sludge deposition below the circulation passages.

In addition, in the method using the circulation passage formed in the vertical direction, air supplied from below into the circulation passage is made to float in the circulation passage as air bubbles, and the floating force of these bubbles can form a water flow. The advantage of this method is that the vibration caused by the air bubbles can efficiently separate the sludge from the filter material, killing two birds with one stone by forming a water flow and separating the sludge. This method is
This is achieved by a filter media circulation type wastewater purification device in which air is supplied from below into the circulation passage, causing it to rise as bubbles within the circulation passage, and the floating force of these bubbles creates a water flow.

The above method can also be implemented by defining circulation passages horizontally using multiple partition walls installed inside the septic tank and creating a water flow in the circulation passage that flows in the opposite direction to the direction of sewage flow. This method is particularly suitable for large-scale purification processes such as river purification. This method is realized by a filter media circulation type sewage purification device that defines circulation passages horizontally using multiple partition walls installed inside the septic tank and creates a water flow in the circulation passage that flows in the opposite direction to the direction of sewage flow.

Regarding the method using this horizontally formed circulation passage, the circulation passage may be formed as a single passage in the center of the septic tank, or as a pair of circulation passages along the left and right side walls of the septic tank. This method is realized by a filter media circulation type sewage purifier in which a single circulation passage is formed in the center of the septic tank, or a filter media circulation type sewage purifier in which a pair of circulation passages are formed along the left and right side walls of the septic tank. Furthermore, in order to efficiently separate sludge from the filter media and to efficiently treat this sludge, a filter media circulation type sewage purifier can be used in which a vibration means for vibrating the filter media is provided in the circulation passage and a sludge deposition pit is provided downstream of the vibration means by a predetermined distance in the water flow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a filter medium circulation type wastewater purification apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view taken along the line indicated by the arrows II-II in FIG.

FIG. 3 is a schematic cross-sectional view of a filter medium circulation type wastewater purification device according to a second embodiment.

FIG. 4 is a schematic cross-sectional view of a filter medium circulation type wastewater purification device according to a third embodiment.

FIG. 5 is a schematic plan view of a filter medium circulation type wastewater purification device according to a fourth embodiment.

FIG. 6 is a schematic cross-sectional view taken along the line VI-VI of FIG.

FIG. 7 is a schematic cross-sectional view taken along the line VII-VII of FIG.

FIG. 8 is a schematic perspective view of a filter medium circulation type wastewater purification device according to a fourth embodiment.

FIG. 9 is a schematic plan view showing the layout of a filter medium circulation type wastewater purification apparatus according to a fourth embodiment.

Figure 10 is a schematic cross-section of the river.

FIG. 11 is a schematic plan view of a filter medium circulation type wastewater purification device according to a fifth embodiment.

[Mode for Carrying Out the Invention]

The following describes an example of the present invention.

In the following description of each embodiment, the same reference numerals are used for parts common to the embodiments, and duplicated descriptions are omitted where appropriate.

Furthermore, although the embodiments described below relate to an aeration type, the present invention is not limited to an aeration type and can also be used in an anaerobic type.

First Embodiment The filter medium circulation type wastewater purifier D1 of this embodiment has a circulation passage for the filter medium A in the septic tank 1 as shown in Figs.
It has 3p.

As will be understood from the explanation that follows, filter material A must have buoyancy, that is, its specific gravity is slightly smaller than that of sewage, for example, about 0.95-0.98, so that it can float in water with moderate buoyancy, and also have the property that it does not get entangled with each other.As filter material A that has this kind of characteristics, the spherical filter material shown in the Japanese Patent No. 1343032 (Patent Publication No. 2440 of 1986) is the best.

When such filter media A is filled into the septic tank 1, due to its floating property, it fills downward from the wastewater surface M, forming a filter bed Ab, which is an aggregate of filter media A. The wastewater is purified by the aerobic bacteria that grow in this filter bed Ab. The amount of filter media A filled is preferably 55 to 60% of the wastewater volume in the septic tank 1.

The septic tank 1 has a ceiling 41, a floor 42, and four side walls 43, 43, ...
..., with a sewage inlet pipe 9 on one side wall 43 and a purified water outlet pipe 10 on the other side wall 43, and further below that a bottom plate 7 is provided, floating slightly above the floor 42. This bottom plate 7 is used to prevent filter media A, which will be described later, from reaching the bottom of the septic tank 1 when the sewage is drained from the tank, and can be formed in the shape of a grate or a mesh.

The circulation passage 3p is defined and formed by a cylindrical body 3 that is open at the top and bottom. The cylindrical body 3 is suspended in the septic tank 1 by a bracket 5, that is, the upper end 3u maintains a certain distance La from the water surface M of the wastewater, and the lower end 3d maintains a certain distance La from the bottom line BL of the filter bed Ab.
are placed with a constant interval Lb.
As will be understood from the following explanation, in order to make the circulation of the spherical filter material A smoother, the inner diameter and spacing of the cylindrical body 3 are
Lb is more than twice the diameter of filter material A, and the interval La is
It is preferable that the diameter is equal to or larger than that of the first electrode.
The tube 3 may be either a circular cylinder or a rectangular tube.

An air supply pipe 4 for supplying air is arranged in this circulation passage 3p with its air supply port 4 facing the lower part of the circulation passage 3p.

Furthermore, below the circulation passage 3p, a pit 11 for sludge deposition is recessed into the floor 42, and sludge deposited in this pit 11 can be appropriately discharged by a suction machine 12 connected to a pump P3.

The aeration pumps P4 installed at both ends of the septic tank 1 serve to supply air for aeration and also to collect sludge and the like deposited on the floor 42 in the parts other than the pit 11 into the pit 11. That is, the aeration pumps P4 supply air in the direction indicated by the arrow X.
In this way, water is supplied to the entire septic tank 1, and the pressure of the supplied air causes a water flow along the floor 42, collecting sludge and the like in the pit 11.

In conjunction with the provision of such an air diffusion pump P4, a partition 44 is provided, and the filter medium A is removed by this partition 44, and the air diffusion pump P4
A space 45 for maintenance and management is provided, and a manhole 46 is provided above this space 45.

Such a filter medium circulation type wastewater purifying apparatus D1 can effectively prevent the filter medium A from being clogged with sludge or the like by continuously circulating the filter medium A.

That is, bubbles caused by the air supplied through the air supply pipe 12 are caused to float up in the circulation passage 3p, and the floating force of these bubbles creates a water current of sewage originating from the circulation passage 3p, and this water current causes the filter media A in the septic tank to move circulatoryly, forming a continuous circulation flow S. More specifically, as mentioned above, the buoyant filter media A forms a filter bed Ab in a packed state from the water surface M to the bottom line BL, but as the water current is formed, the bottom line BL at the lower end 3d of the cylinder 3 becomes funnel-shaped, and the filter media A arranged on the inclined surface of this funnel gradually enters the circulation passage 3p. Then,
The filter media A rises through the circulation passage 3p and exits it at the top. The air bubbles bursting at the water surface M cause the filter media A to settle downward, dispersing into the surrounding area and returning to the funnel-shaped inclined surface. The filter media A then move sequentially as a circulating flow S, resulting in the filter bed Ab as a whole moving gently, like a glacier. The strength of the circulating flow S can be adjusted by adjusting the amount of air supplied, from "strong" to "weak," depending on the concentration of the wastewater, the degree of purification, and other conditions. Experiments using wastewater of average concentration demonstrated that even a few pieces of filter media A rising through the circulation passage 3p per minute was sufficient.

Furthermore, this filter medium circulation type wastewater purification device D1 is
The sludge adhering to the filter material A can be automatically and constantly separated from the filter material A, and the separated sludge can be efficiently collected without being dispersed throughout the septic tank 1.

Specifically, the bubbles generated by the air supplied to the circulation passage 3p create a water flow as described above, and at the same time, they cause intense vibrations to the filter medium A that moves on this water flow.
The sludge is efficiently separated from the filter material A. Then, the separated sludge flows through the circulation passage 3p defined and formed by the cylindrical body 3.
This prevents the waste from diffusing throughout the septic tank 1, and it settles in a pit 11 below, from which it is removed by a suction machine 12.

The sludge not only peels off from the filter media A in the circulation passage 3p, but also peels off to a small extent from other filter media A, and also separates and settles directly from the wastewater.
The air is collected in a pit 11 by an aeration pump P4 and discharged to a suction machine 12.

Second Embodiment The filter medium circulation type wastewater purifying apparatus D2 shown in Fig. 3 is a second embodiment, and is an example in which a plurality of circulation passages 3p are provided. Other points are the same as those of the first embodiment.

The filter medium circulation type wastewater purifier D3 shown in Fig. 4 is a third embodiment, and uses an air diffusion pipe 8 instead of the air diffusion pump P4 in the first embodiment.
In this example, the partitions 44, spaces 45, manholes 46, etc. related to the above are not provided. The other points are the same as those of the first embodiment.

Fourth Embodiment The filter medium circulation type wastewater purification device D4 of this embodiment is suitable for large-scale purification treatment, such as when it is installed near a river R as shown in Figure 9 and the river R is purified.

Specifically, as shown in Figures 5 to 8, this filter media circulation type wastewater purification device D4 has a horizontal circulation passage 50P, whereas the filter media circulation type wastewater purification device D1 of the first embodiment has a vertical circulation passage 3p.

The circulation passage 50P is formed by a pair of partition walls 54, 54 arranged laterally with respect to the septic tank 51, i.e., along the direction of movement of sewage that flows in from the sewage inlet 52 and moves toward the sewage outlet 53 (FIG. 6).
It is divided and formed by erecting them in parallel.

The partition wall 54 is erected from the floor 55 of the septic tank 51 to the ceiling 56 of the septic tank 51, and therefore the circulation passage 50P is formed in a state that almost completely separates the central part of the septic tank 51 from other parts.

In the circulation passage 50P, a water flow is formed by a water flow forming means 56 provided on the purified water outlet 53 side in the opposite direction to the aforementioned direction of movement of the wastewater, and the circulating flow S of the filter material A is carried by this water flow.
The filter medium A is then circulated as a circulating flow S, and the same flow state of the filter medium Ab as that described above in the first embodiment is obtained. Here, the circulation speed of the filter medium A is:
The cycle will be determined depending on the state of the wastewater and the treatment conditions, but normally it will be sufficient to achieve circulation once a week or once a month.

A pair of rotation guides 57 are provided at the entrance of the circulation passage 50P, one on each side, to facilitate introduction of the filter medium A into the circulation passage 50P.

Furthermore, within the circulation passage 50P, vibration means 58 are provided at appropriate intervals to apply vibrations to the filter media A to separate the sludge, and a sludge deposition pit 59 is provided in pairs with the vibration means 58 at a predetermined distance downstream of the water flow from the vibration means 58.
is separated from the vibration means 58 by a predetermined distance.
This is because the sludge separated from the filter material A at 58 is carried downstream by the water current and deposited in the path indicated by arrow Y in Figure 6. The sludge deposited in the pit 59 is discharged in the same manner as in the first embodiment.

In this way, by separating the sludge from the filter material A at a specific location within the circulation passage 50P that is separated from other locations, the sludge can be efficiently separated from the filter material A without spreading throughout the entire septic tank 51, thereby further improving the efficiency of preventing clogging and, ultimately, the purification efficiency.

A sedimentation tank 60 is provided on the sewage inlet side of the filter media circulation type sewage purifier D4, and the sewage is first treated by settling and separating floating matter of a size that is not suitable for filter media treatment in this sedimentation tank 60, and is then supplied to the filter media circulation type sewage purifier D4. A water intake pit 61 is provided in front of the sedimentation tank 60, and river water blocked by a weir Rd installed in the river R is introduced into the sedimentation tank 60 through this water intake pit 61. Furthermore, the filter media circulation type sewage purifier
The discharge pit is provided on the side of the purified water discharge outlet 53 of D4.
62, which is used to return the purified water to River R.

Fifth Embodiment The filter medium circulation type wastewater purification device D5 of this embodiment is a modification of the fourth embodiment, in which a pair of circulation passages 60P are formed on the left and right sides along the side wall of the septic tank 51. The other configurations are substantially the same as those of the fourth embodiment.

[Industrial Applicability]

The filter media circulation type wastewater purification method and device of this invention uses a water flow forming means to create a water flow in a circulation passage partitioned and formed within the septic tank, and this water flow circulates the filter media within the septic tank, so the filter media moves constantly and orderly, and this constant movement effectively prevents the filter media from clogging, and the orderly movement constantly separates sludge from the filter media without causing it to diffuse throughout the septic tank, thereby greatly contributing to improving the efficiency of filter media type wastewater purification.

Claims (7)

[Claims] [Claim 1] A method for purifying wastewater in which a filter bed, which is an aggregate of filter media, is formed by placing a large number of floating filter media in a septic tank and utilizing the bacteria propagated in this filter bed, wherein a circulation passage is defined and formed in a direction parallel to the direction of movement of the wastewater by a partition wall erected in the septic tank, and a water flow forming means is used to form a water flow in this circulation passage in the opposite direction to the direction of movement of the wastewater, and the filter media removed from one end of the filter bed on this water flow is similarly carried on the water flow, moved through the circulation passage, and then returned to the filter bed at the other end. 2. A filter medium circulation type wastewater purification method according to claim 1, wherein a single circulation passage is formed in the center of the septic tank. 3. A filter medium circulation type wastewater purification method according to claim 1, wherein a pair of circulation passages are formed on the left and right sides along the side wall of the septic tank. [Claim 4] A sewage purification system in which a filter bed, which is an aggregate of filter media, is formed by storing a large number of floating filter media in a septic tank, comprising: a circulation passage partitioned and formed in a direction parallel to the direction of movement of the sewage by partition walls erected in the septic tank; and a water flow forming means for forming a water flow in the circulation passage that flows in the opposite direction to the direction of movement of the sewage, wherein the filter media removed from one end of the filter bed on the water flow in the circulation passage are similarly placed on the water flow and moved through the circulation passage, and then returned to the filter bed at the other end of the filter bed. 5. A filter medium circulation type wastewater purification device according to claim 4, wherein one circulation passage is formed in the center of the septic tank. 6. A filter medium circulation type wastewater purification device according to claim 4, wherein a pair of circulation passages are formed on the left and right along the side wall of the septic tank. [Claim 7] A filter media circulation type sewage purification device as described in any one of claims 4 to 6, which has a vibration means for vibrating the filter media in the circulation passage and a pit for sludge deposition located a predetermined distance downstream of the water flow from the vibration means.