JPH0773704B2 - Biological equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides a method of removing organic matter or nitrogen from low concentration to high concentration such as river water or lake water with relatively advanced pollution, or sewage / human waste / industrial wastewater. The present invention relates to a technique for purifying contained water with microorganisms.

[Conventional technology]

There are many biological treatment technologies since ancient times, and they are still widely used today. Among them, those using a medium for adhering microorganisms have made many technological advances in recent years, and in particular, the method using a granular medium is a very useful value, such as high load operation is possible. there were.

[Problems to be solved by the invention]

However, when a granular material is used as a medium, it tends to be clogged because of a low void ratio, and cleaning is indispensable.

For example, as in the gravel-to-gravel contact method, a large amount of excess sludge is mixed into the treated water when washed, and when the washing is excessive, the amount of microorganisms is significantly reduced, which causes deterioration of the treatment.
As a matter of course, if cleaning is insufficient, clogging occurs immediately and it is difficult to control the degree of cleaning.

In addition, as another method, a method of backwashing using treated water or air has emerged as a measure against clogging, but since a large amount of treated water or air is used at one time, the backwashing facility becomes huge and Many problems remained, such as the need to separately consider the treatment of cleaning wastewater.

The present invention seeks to provide a drastic solution to the clogging, which is a fundamental problem that is inevitable and inevitable when the particulate matter is adopted as a biofouling medium.

[Means for solving problems]

The present invention forms a packed layer of a granular medium for adhering microorganisms in a tank provided with a raw water inlet in the upper part, and arranges an air lift pipe having a lower opening in the lower part of the packed layer, and an upper part of the air lift pipe. Is located above the packing layer and below the water level in the tank at the time of treatment, and communicates with the media separation chamber, and at the bottom of the media separation chamber there is provided a media reflux passage communicating with and opening above the packing layer and the media separation chamber. A biological drainage device is provided, in which a washing drainage outlet is opened, and further, an air diffuser and a water collecting device for collecting and discharging treated water are provided in a lower portion of the packing layer. .

[Work]

The operation of the present invention will be described below with reference to the drawings showing the embodiments.

In FIG. 1, a raw water inlet 2 is provided in an upper part of a tank 1, and a packed layer 4 of a granular medium 3 for adhering microorganisms is provided in the tank 1.
Are formed. The granular medium 3 for adhering microorganisms may be any granular medium that can be transported in water, such as sand, gravel, anthracite, activated carbon, lightweight aggregate, plastic, and artificial stone.

In the packing layer 4, a lower part is opened to a lower part inside the packing layer 4, an upper part is opened to an upper part from the packing layer 4, and an air lift pipe 6 having an air introduction pipe 5 connected to the lower part is provided. The upper opening of the tank is connected to the inside of the medium separation chamber 7 defined near the water level in the upper part of the tank 1,
The inner bottom portion is provided with a medium recirculation path 8'for recirculating the granular medium 3 having an opening 8 communicating with the liquid on the packing layer 4, and at the upper part of the medium separation chamber 7 there is a cleaning drainage outlet 9. It is open.

The lower opening of the air lift pipe 6 is located near the bottom surface of the tank 1, more specifically 50 to 50
Places about 100 mm apart are desirable. This is because if it is 50 mm or less, suction resistance at the lower opening of the air lift pipe 6 increases and the pumping effect decreases, and if it is 100 mm or more, the granular medium 3 remains at the inner bottom of the tank 1 and tends to become a dead space. . Further, the upper opening of the air lift pipe 6 is located between the upper end of the packing layer 4 and the upper end of the tank 1, and is set so as to be below the water level surface during processing. If there is an upper opening below the water level surface, the discharge energy at this opening is attenuated by the water above it, so that the water lifted by the air lift pipe 6 and the granular medium 3 are scattered. Therefore, it is not necessary to additionally install a shatterproof plate or the like, and SS and an excess tail separated from the granular medium 3 can be continuously and promptly discharged under the water surface.

Further, it is preferable that the bottom of the medium separation chamber 7 be inclined toward the opening 8 as in the illustrated example, so that the separated granular medium 3 becomes slippery toward the opening 8.

In addition, the upper opening of the air lift pipe 6 is a draft tube.
It is preferable that the draft tube 10 is surrounded by 10, and the draft tube 10 and the opening 8 at the bottom of the medium separation chamber 7 are communicated with each other.

Further, in the lower part of the packing layer 4, an air diffuser 11 for uniformly diffusing air to maintain the packing layer 4 in an aerobic state,
A water collecting device 12 for collecting and outflowing the treated water that has passed through the packed bed 4 and is discharged, and the treated water outlet 13 of the water collecting device 12 should be once raised as in the illustrated example. Is preferred.

It is desirable to arrange the water collecting device 12 below the air diffusing device 11.If the air diffusing device 11 is below the water collecting device 12, air may be mixed into the water collecting device 12 or due to air diffusion. There is a possibility that the biological water separated from the granular medium 3 may be mixed due to the stirring action and the treated water SS will become high. Therefore, the water collecting device
It is desirable that 12 is provided between the lower opening of the air lift pipe 6 and the air diffuser 11.

Further, the amount of the granular medium transferred by the air lift pipe 6 varies depending on the increase or decrease in the amount of the air supplied, but assuming that the amount of the air supplied is the highest economical efficiency point, the amount of the granular medium transferred by the air lift pipe 6 Is determined by the cross-sectional area of the air lift pipe 6. Therefore, if the cross-sectional area of the air lift pipe 6 is determined, on the contrary, the medium transfer amount can be obtained. From this point of view, as a result of an experiment using an air lift pipe having an inner diameter of 25 to 100 mm, it is appropriate that the separation area of the medium separation chamber 7 is within the range of 3 to 20 times the cross-sectional area of the air lift pipe 6. The sedimentation separation speed of the granular medium 3 in the medium separation chamber 7 is in the range of 0.5 to 3 m / min.

Then, the raw water to be treated is introduced from the raw water inlet 2 to the upper part of the tank 1 and flows downward in the packed bed 4 maintained in an aerobic state by the aeration from the air diffuser 11. However, the aerobic biological treatment by the biofilm generated on the surface of the granular medium 3 as the raw water flows through the packed layer 4 and the excessive action are performed at the same time, and the treated water becomes the treated water in the water collecting device 12. Water is collected and discharged through the treated water outlet 13.

On the other hand, when air is introduced into the air lift pipe 6 through the air introduction pipe 5, the granular medium 3 in the lower part of the packing layer 4 is sucked into the air lift pipe 6 together with water from the lower opening of the air lift pipe 6. As a result, the biofilm excessively attached to the granular medium 3 is peeled off while rising in the air lift pipe 6. At this time, since the granular medium 3 is slurried with a part of the treated water reaching the lower portion of the packing layer 4, the granular medium 3
The cleaning effect of can be expected. The granular medium 3 and the separated biofilm (excess sludge) are guided from the opening 8 to the medium separation chamber 7 through the draft tube 10 (part of the granular medium 3
May directly return to the packing layer 4 without reaching the medium separation chamber 7). In the medium separation chamber 7, the granular medium 3 and the excess sludge are separated, the granular medium 3 settles, flows out from the opening 8 at the bottom through the medium recirculation passage 8 ′, and is recirculated to the packed bed 4.
The cleaning wastewater containing excess sludge is discharged from the cleaning wastewater outlet 9 to the outside of the system.

In this way, the packed bed 4 is operated by the operation of the air lift.
Gradually shifts downward, and the amount of organisms retained in the packed bed 4 is maintained substantially constant, and stable treatment is continued.

Such a biological filter is provided in a tank 1 as shown in the second illustrated example.
Although a plurality of planar shapes can be used side by side as a square shape, it may be a round rice cake type or a single tank.

In the above action, if Q _A is the amount of water pumped by the air lift, Q _W is the amount of water discharged from the cleaning drainage outlet 9 of the medium separation chamber 7, then if Q _A > Q _W , part of Q _A It is mixed with raw water and reprocessed, and in any case of Q _A = Q _W and Q _A <Q _W , it is discharged without being mixed with Q _A raw water. Therefore, it is not necessary to strictly manage the Q _W, it is possible to reduce the Q _W, no fear of deteriorating the quality of treated water.

By the way, the water level in the tank 1 varies depending on the increase / decrease in the amount of microorganisms adhering to the granular medium 3, the degree of SS in the raw water captured in the packed layer 4, or the variation in the amount of treated water. That is, the cleaning wastewater flowing out from the cleaning wastewater outlet 9 is
A large amount of water flows when the water level in the tank 1 is high, and a small amount flows when the water level is low. However, in order to keep the cleaning efficiency constant and maintain a stable treatment effect, it is preferable that the outflow amount of the cleaning drainage be constant.

As an adjusting device for keeping the outflow amount of the cleaning wastewater constant, it is easy and easy to install a constant flow valve in the outflow pipe connected to the cleaning wastewater outlet 9, but the valve can be clogged. Therefore, it is necessary to add washing means such as washing with water. Therefore, in the outflow pipe connected to the treated water outlet 13, it is better to provide a water level adjusting valve that can adjust the outflow amount of the treated water by changing the opening so that the water level in the tank becomes constant. preferable.

Further, as another adjusting device for keeping the outflow amount of the cleaning drainage constant, the water level of the cleaning drainage outlet 9 can be kept lower than the water level in the tank with a constant water level difference h.

For example, the washing / drainage outlet 9 can be moved up and down in a telescopic manner, and is raised / lowered in response to the fluctuation of the water level in the tank to keep the water level of the washing / drainage outlet 9 lower than the water level in the tank with a constant water level difference h. You can

Further, as a suitable example of the adjusting device for automatically keeping the water level difference h constant, as shown in FIG. 3, the cleaning drainage outlet 9 is fixed to the medium separation chamber 7, and the cleaning drainage outlet is fixed. The outer side of the medium separation chamber 7 of 9 is guided to the outside of the tank through the flexible tube 21, and the medium separation chamber 7 is suspended on the float 22 so as to have a constant water level between the water level of the cleaning drainage outlet 9 and the water level in the tank. The difference h is maintained, and the medium separation chamber 7 slides up and down the air lift pipe 6 in accordance with the fluctuation of the water level in the tank. Therefore, the granular medium 3 and the excess sludge discharged from the upper opening of the air lift pipe 6 are separated in the medium separation chamber 7, and the granular medium 3 settles and is returned to the tank through the medium return passage 8 '. Like

Furthermore, instead of the example shown in FIG. That is, the medium separation chamber 7 is fixed, the cleaning drainage outlet 9 is supported in the medium separation chamber 7 by the flexible tube 21, and the cleaning drainage outlet 9 is suspended on the float 22 to set the water level of the cleaning drainage outlet 9 and the medium. A constant water level difference h is maintained between the water level in the separation chamber 7 and the cleaning / drainage outlet 9 is moved up and down in accordance with the fluctuation in the water level in the medium separation chamber 7. Therefore, the cleaning / drainage outlet 9 also rises / falls following the water level of the medium separation chamber 7 which fluctuates with the fluctuation of the water level in the tank,
The water level difference h between the water level of the cleaning drainage outlet 9 and the water level of the medium separation chamber 7 (the water level difference h between the water level of the cleaning drainage outlet 9 and the water level in the tank) is always kept constant, The cleaning efficiency of the flow medium 3 and the amount of cleaning waste water are also kept constant.

〔Example〕

Next, a comparative example of the present invention and the conventional method will be shown. In the conventional method, the method shown in JP-A-56-91889 in which backwashing is performed as a measure against clogging was used.

In this comparative example, the sewage primary treated water was used as raw water, and the treated water was treated at a treated water amount of 100 m ³ / day and a BOD load of about 3 kg / m ³ · day. Table 1 shows the equipment and Table 2 shows the comparison of the treatment results.

Here, as the filling medium, an artificial lightweight aggregate having a specific gravity of 1.8 and a particle size of 3 to 6 mm was used.

As is clear from these Tables 1 and 2, according to the present invention, a backwash treatment water tank, a temporary drainage storage tank for equalizing the amount of water, a backwash pump, a backwash blower, and other incidental equipment are provided. While it is not necessary and the equipment is significantly simplified, the quality of treated water is not inferior to that of the conventional method, and the amount of surplus sludge discharged is less than half.

〔The invention's effect〕

As described above, according to the present invention, it is possible to drastically solve the clogging that is inevitably caused when the particulate matter is used as the medium for attaching organisms. That is, the granular medium is placed under a strong stirring condition while being transported in small amounts in a slurry state, and excess sludge is reliably separated, and the separated sludge and the like can be continuously and rapidly discharged under the water surface. .
Furthermore, the dispersion medium of this slurry is the same as the treated water, and has a higher cleaning effect than the case of using raw water, and there is no need to use special water for cleaning. Sludge can be easily separated, and at the same time, the amount of excess sludge discharged can be significantly reduced.

In addition, unlike the conventional method, there is no need for backwashing, so stable treatment can be expected at all times, and above all, auxiliary equipment required for backwashing can be greatly reduced, and extremely rational treatment can be performed. is there.

[Brief description of drawings]

The drawings show the embodiments of the present invention. FIG. 1 is a vertical sectional view, FIG. 2 is a plan view, FIG. 3 is a vertical sectional view showing an example of a medium separation chamber, and FIG. FIG. 1 ... Tank, 2 ... Raw water inlet, 3 ... Granular medium, 4 ...
Packing layer, 5 ... Air introduction pipe, 6 ... Air lift pipe, 7
... Medium separation chamber, 8 ... Opening, 8 '... Medium return path,
9 ... Washing discharge outlet, 10 ... Draft tube, 11 ...
… Air diffuser, 12 …… Water collector, 13 …… Treated water outlet, 21
...... Flexible tube, 22 ...... Float, h ...... Water level difference.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hitoshi Kimura 4720 Fujisawa, Fujisawa-shi, Kanagawa Ebara Research Institute, Ltd. (72) Inventor Masaaki Osato 1-6-27 Konan Minato-ku, Tokyo In-company (72) Inventor Koichi Yamamoto 1-6-27 Konan, Minato-ku, Tokyo Ebara Infilco Co., Ltd. (56) Reference JP-A-61-291099 (JP, A)

Claims (4)

[Claims] 1. A packing layer 4 of a granular medium 3 for adhering microorganisms is formed in a tank 1 having a raw water inlet 2 at the upper part thereof, and an air lift pipe 6 having a lower opening is provided at a lower part inside the packing layer 4. ,
The upper part of the air lift pipe 6 is located above the packing layer 4 and below the water level in the tank at the time of processing so as to communicate with the inside of the medium separation chamber 7, and the bottom part of the medium separation chamber 7 is located above the packing layer 4. A medium reflux passage 8'which is open for communication is provided, a washing / drainage outlet 9 is opened in the medium separation chamber 7, and an air diffuser 11 and a water collecting device for collecting and discharging treated water at a lower portion of the packing layer 4.
A biological filter characterized by having 12 and 12 installed. 2. The biological filter according to claim 1, wherein the upper opening of the air lift pipe 6 is communicated with the medium separation chamber 7 via a draft tube 10 surrounding the opening. 3. The biological filter according to claim 1, wherein the water collecting device 12 is provided between a lower opening of the air lift pipe 6 and an opening of the air diffuser 11. 4. The separation area of the medium separation chamber 7 is set to 3 to 20 times the cross-sectional area of the air lift pipe 6 as claimed in claim 1.
The biological filter according to any one of items 1 to 3.