JP2000037697A - Water treatment method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep treatment capacity in a water treatment method and apparatus by aeration type gravel purification, to allow excessive sludge generated between gravels to flow out of the system aerlier and to prevent the spoilage of sludge or the clogging between gravels to enhance treatment capacity. SOLUTION: A water tank is divided into a plurality of purifying areas 11, 12, 13 and a final stage single sludge area 14, and gravels 2 and air diffusers 3 are arranged to the purifying areas 11, 12, 13 and water is allowed to flow successively from the upstream side and treated water is introduced into the sludge area 14 to sediment sludge to allow supernatant water to flow out and aeration is collectively performed in the purifying areas 11, 12, 13 successively and cyclically from the upstream area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water treatment method and apparatus for purifying raw water (to-be-treated water) such as city drainage or river water, which is an aeration type water purifier comprising a water tank in which water is laid. Regarding improvement. This type of water treatment apparatus is particularly suitably used for treating low BOD wastewater, for example, wastewater having a BOD of 100 mg / L or less.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a water treatment apparatus using a rake basically comprises a water tank 1 for introducing and purifying raw water, a rake 2 laid in the water tank, and a water tank. It is constituted by an air diffuser 3 arranged below the rake 2. Aquarium 1
Is provided with an inlet pipe 4 for raw water and an outlet pipe 5 for treated water at the other end of the water tank 1. A blower 6 is connected to the air diffuser 3 via a pipe.

[0003] Raw water introduced into the water tank 1 through the introduction pipe 4 is purified by sludge microorganisms staying therein.
In the water tank 1, air inserted from the blower 6 is released through the air diffuser 3, and aeration (aeration) is performed between the rakes 2 to promote biological treatment. That is, the foreign matter in the raw water undergoes the biological oxidation treatment by the microorganisms inhabiting the reki 2 and the floating microorganisms, the raw water is separated into sludge and the treated water, and the treated water flows out from the outflow pipe 5. .

[0004]

In such a conventional water treatment apparatus, the inside of the water tank 1 is a single tank, and the amount of surplus sludge generated is large because the sludge microorganisms therein are the same kind of microorganism. At the same time, as time elapses, more aeration is performed from places with low resistance between the rakes, and a large amount of sludge stays and aeration from places with high resistance is stopped. Therefore, the aeration became uneven, and the excess sludge was accumulated in places where air was difficult to flow out and stayed for a long time, and that portion became anaerobic, clogging occurred between the rolls, and the processing performance was reduced. Especially during the rainy season, a large amount of sand and mud was caught in the gaps, causing clogging, and the treatment performance tended to be significantly reduced.

[0005] An object of the present invention is to solve the above-mentioned problems of the prior art, and therefore, it is necessary to maintain the treatment performance of a water treatment apparatus using a reki and quickly remove excess sludge generated between the rekis. The purpose of the present invention is to prevent the sludge from being rotted and clogging between reeds, to enhance the processing performance of the entire apparatus and to stabilize the performance for a long period of time.

[0006]

In order to achieve the object of the present invention, a water treatment method according to the present invention is characterized in that, in a method of purifying raw water introduced into a water tank between aeration tanks, there is provided a method for purifying raw water. Raw water is sequentially circulated through the divided areas, and aeration in each of the above sections is sequentially performed from the upstream section (previous stage) to perform aeration between the rakes, and the treated water in the last section is introduced into the sludge section. This is to settle the sludge in the treated water, and by performing aeration intensively for each area in the water tank, the clogging between the rakes is removed and the treatment performance is maintained.

Further, the apparatus according to the present invention for carrying out the above-mentioned method is characterized in that the inside is divided into a plurality of purification zones and a single sludge zone on the outflow side, and raw water to be purified is supplied from one purification zone to the subsequent one. A water tank that is sequentially circulated to the area, a rake laid in each purification area and an air diffuser installed under the rake, a branch pipe connected to each air diffuser, and a A pipe consisting of a common pipe connected to a branch pipe, a blower connected to the common pipe for sending air for aeration, and to enable successive aeration in a series of purification zones. And an automatic valve installed in each branch pipe, and preferably three, four or five said purifying sections are provided in the water tank.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; As shown in FIGS. 1 and 2, the water treatment apparatus according to the present invention basically includes a water tank 10,
The raw water introduced into the water tank 10 through the introduction pipe 4 is constituted by a rake 2 laid therein and an air diffuser 3 for performing aeration in the water tank, and is contacted by sludge microorganisms living in the water tank. Purified by oxidation.

In the water tank 10 used in this water treatment method, the inside of the tank is divided into an appropriate number of sections along the longitudinal direction, and the last stage, that is, the most downstream area is a sludge area for sludge sedimentation. And each zone except the sludge zone is configured to be able to be sequentially aerated for each zone.
By using such a water tank, this water treatment method circulates raw water sequentially to each area from the upstream area in the water tank, sediments the sludge in the sludge area at the final stage, and discharges treated water as supernatant water. In addition, the aeration is performed sequentially from the upstream side for each area, and the aeration is concentrated through the air diffuser in that area, so that the sludge blocking the space between the rakes is lifted, separated, and regenerated. (Cleaning).

The water treatment apparatus will be described in detail with reference to FIGS. 1 and 2. In the illustrated example, the inside of the water tank 10 is divided into four sections by three partitions 7, 8, 9, and the preceding section 11 and the preceding section 11 are divided into four sections. The next two zones 12, 13 are used as a purification zone, and the last stage zone 14 is used as a sludge zone. The raw water introduced from the introduction pipe 4 into the area 11 in the water tank is preferably transferred to the subsequent area by an overflow as shown in the figure. In this case, each partition is configured as a partition wall.

As shown in FIG. 1 and FIG.
In order to perform a purification action by sludge microorganisms in the insides 1, 12, and 13, a wrench 2 is laid inside, and air diffusers 3a, 3b, and 3c are installed below the wrecks 2, respectively. These purifying zones 11, 12, 13 are preferably configured to the same volume. The rake 2 may be the same as the conventional one. The air diffuser in each area is constituted by an appropriate number of air diffusers. A gas-permeable covering such as a perforated plate may be interposed to prevent the air discharge holes of the air diffusers from being closed by the recess 2.

The air diffusers in each zone are via their respective branch pipes, ie the air diffuser 3a is via its branch pipe 15a, the air diffuser 3b is via its branch pipe 15b and the air diffuser 3c.
Are connected to a common pipe 15 via a branch pipe 15c, and a blower 6 is installed at one end of the common pipe 15. Therefore, a pipe between the blower 6 and each air diffuser is constituted by the common pipe 15 with these branch pipes.

The feature of this water treatment apparatus is that the inside of the water tank is divided into an appropriate number of sections as described above, and that the aeration can be performed in each section. An automatic valve which is automatically opened and closed by a controller or a timer is installed. That is, as shown, an automatic valve 16a is provided in the branch pipe 15a,
The automatic valve 16b is installed in the branch pipe 15c, respectively. These automatic valves may be of any type or structure. In one example, a solenoid valve is used.

The sludge section 14 serves to receive the treated water in the preceding stage and settle and separate the sludge contained therein. Therefore, no recoil 2 and a diffuser are installed in the section. As shown in FIG. 1, the sludge section 14 is provided with an opening 17 for drawing sludge near the bottom thereof, and a sludge drawing pipe 18 is connected to the opening. The sludge withdrawal pipe 18 is connected to a vacuum source (not shown) such as a vaccum car, and the sludge settled in the sludge area is periodically withdrawn.

Although not shown in FIGS. 1 and 2, if desired, a baffle plate (deflecting plate) is provided near the raw water introduction side in each area, and the raw water immediately after introduction is provided by the baffle plate. Descends to prevent the raw water from flowing directly to the outlet side, ensuring that the raw water remains in the area for a sufficient time to be treated by the sludge microorganisms.

In this water treatment apparatus, raw water enters the purifying section 11 in the water tank 10 from the introduction pipe 4, and then flows to the next purifying section 12 and further to the purifying section 13, from which the overflow water flows. The water flows into the sludge section 14, and the supernatant water in the section is discharged from the outflow pipe 5, and the aeration is sequentially performed from the upstream side in each of the purification sections 11, 12, and 13. That is, first, only the automatic valve 16a of the purification section 11 is opened, the other automatic valves 16b and 16c are closed, and all the air from the blower 6 is diffused through the common pipe 15 and the branch pipe 15a. , And release it from there.

As described above, when the aeration in the purification section 11 has passed for a certain period of time, for example, one hour, the automatic valve 16a of the next purification section 12 is closed while the automatic valve 16c of the purification section 13 remains closed. Is opened, air is released from the air diffuser 3b in the area 12, and aeration is performed for a certain period of time. Next, the automatic valve 16a is kept closed, the automatic valve 16b of the purification section 12 is closed, and the automatic valve 16c of the purification section 13 is opened. In the section 13, air is released from the air diffuser 3c to perform aeration. When the aeration in the zone 13 is performed for a certain period of time, the automatic valve 16c is closed and the automatic valve 16a in the purification zone 11 is opened, and the above operation is repeated. The aeration time in each area is appropriately set according to the structure of the apparatus, the state of raw water, the treatment conditions, and the like.

When the BOD of raw water is low, for example, B
When the OD is 5 to 10 mg / L, the aeration in the most downstream purification section 13 is omitted, and the upstream purification section 11,
Aeration may be repeated sequentially at 12, and the area 13 may be used as a settling section. In this case, air is released from the air diffuser 3c at intervals of, for example, about once a month in order to remove excess sludge and sand mud between the rakes in the purification area 13, and the concentrated sludge is removed. Since it can be efficiently transferred to the sludge area 14, it can be effectively used in terms of maintenance and processing performance.

Thus, each of the purification zones 11, 12, 13
By sequentially aeration from the upstream area, excess sludge and sand mud between the rakes 2 in each area are sequentially transferred to the subsequent area, finally introduced into the sludge area 14 and settled there, It is discharged to the outside through the opening 17 and the sludge extraction pipe 18. The supernatant water in the sludge section 14 is discharged through the outlet pipe 5 as treated water.

As shown in FIGS. 1 and 2, the partitions 7 and 8 between the purification sections are also constituted as partition walls, and if the advection between these sections is also carried out by overflow, the purification of those sections is performed. Different biota are formed in the area, so the food chain is advanced, and there is an advantage that the generation of excess sludge is reduced and the treatment performance is improved.

The partitions 7 and 8 between the purification sections need not necessarily be partition walls, and may be formed of a liquid-permeable flat material, for example, a mesh as shown in FIG. A baffle plate 19 is preferably provided on the introduction side in the area. In this case as well, it goes without saying that aeration is performed sequentially from the upstream area.

In the above embodiment, the sludge area 14 is provided at the last stage in the water tank, and three purification areas are provided in the water tank. However, in some cases, the number of purification areas may be other. Preferably, however, three, four or five purification zones are provided. With that number, the treatment performance is effectively improved in the minimum purification area, and an appropriate number of different biota will be generated even when advection is performed by overflow. Only incurring a rise in equipment costs, it does not match the cost needs, and the corresponding improvement in processing performance cannot be expected.

In the illustrated embodiment, the aeration performed sequentially for each section is performed by opening and closing the automatic valve of each branch pipe. However, the aeration may be performed by another method in some cases. Instead of using the air blower 15, a blower may be provided for each air diffuser in each purification area, and the blowers may be turned on and off by a controller. Especially when the capacity of the water tank is large, such a method is also effective.

[0024]

As described above, according to the present invention, the aeration between the rakes is sequentially concentrated from the upstream side at regular time intervals for each of the divided areas in the water tank, so that the aeration intensity increases. Sludge and sand mud staying between the rakes can be removed and clogging can be prevented, so that stable treatment performance can be maintained for a long period of time. Particularly, conventionally, when a large amount of sand and mud flowed in at the beginning of the rainy season, clogging occurred between the legs, but even in such a case, the sand and mud are sequentially transferred to the next area, and clogging can be prevented. . Further, in this water treatment apparatus, the blower for aeration is compared with the case where aeration is performed in the entire water tank,
It becomes possible with a small capacity.

The number of purification zones divided in the water tank is 3,
By setting it to 4 or 5, each area can be effectively used, and especially without increasing the equipment cost.
This is the most favorable number of categories in terms of economy. In addition,
When advection between the sections is performed by overflow,
Independent biota in each area, generating excess sludge,
This has the advantage of reducing stagnation.
The division into five to five purification zones is the optimal number of divisions.

[Brief description of the drawings]

FIG. 1 is a side sectional view schematically showing an example of a water treatment apparatus according to the present invention.

FIG. 2 is a schematic plan view of the water treatment apparatus shown in FIG.

FIG. 3 is a side sectional view schematically showing another embodiment of the present invention.

FIG. 4 is a side sectional view schematically showing a conventional water treatment device of the aeration type between rakes.

[Explanation of symbols]

2: Reki, 3a, 3b, 3c: diffuser, 6: blower, 10: water tank, 11, 12, 13: purification area, 14:
Sludge area, 15: common pipe, 15a, 15b, 15c:
Branch pipe, 16a, 16b, 16c: automatic valve

Claims (3)

[Claims] 1. A method for purifying raw water introduced into a water tank between aeration tanks, wherein the raw water is sequentially circulated through divided areas in the water tank, and aeration in each of the sections is sequentially performed from an upstream area. A water treatment method comprising: performing aeration between rakes to introduce treated water in the downstream section into a sludge section to settle sludge in the treated water. 2. A water tank having an interior divided into a plurality of purification sections and a single sludge section on an outflow side, and raw water to be purified is sequentially passed from one purification section to the subsequent section. A pipe consisting of a rake laid in each purification area and an air diffuser installed under the rake, a branch pipe connected to each air diffuser, and a common pipe connected to those branch pipes. Including a blower connected to said common pipe for delivering air for aeration, and an automatic valve installed on each branch pipe to enable sequential aeration in a series of purification zones. Characterized water treatment equipment. 3. The water treatment apparatus according to claim 2, wherein three, four or five purifying sections are provided in the water tank.