JPH0148079B2 - - Google Patents

Description

Detailed Description of the Invention The present invention involves temporarily retaining wastewater containing BOD components in a wastewater retention tank, passing the wastewater in the wastewater retention tank through a fixed bed contact oxidation tank to perform BOD treatment, and then The present invention relates to an aerobic microbial treatment device that removes suspended solids using a suspended solid separation device.

A fixed-bed catalytic oxidation tank is filled with a filler made of gravel, crushed stone, Raschig ring, honeycomb modules, nets, various plastics, etc., and wastewater containing BOD components is supplied from above or below the filler layer. , and is a device that supplies oxygen by flowing air from the bottom or center of the filler layer, and decomposes BOD components in wastewater by aerobic microorganisms that have grown on the surface or voids of the filler layer. When wastewater is treated with this device, the aerobic microorganisms that have grown on the surface or voids of the filler layer gradually detach and the treated water becomes turbid. It is common to install a separator and use the turbidity separator to remove turbidity from the treated water.

However, if such treatment is continued, the aerobic microorganisms that have grown on the filler layer will enlarge and the filler layer will become clogged, so it is necessary to clean the filler layer from time to time. This cleaning involves injecting water or water and air from the bottom of the filler layer at a flow rate that is much higher than the flow rate for normal wastewater treatment, and forcibly removes excess microorganisms that have grown on the surface or voids of the filler layer. However, since there is a large amount of suspended matter caused by the microorganisms in the cleaning wastewater, it cannot be discharged as is. Therefore, it is possible to treat the washed wastewater with a turbidity separator installed after the fixed bed contact oxidation tank, but the turbidity separator is generally designed to match the wastewater treatment flow rate. However, it is impossible to directly pass the cleaning wastewater, which has a flow rate much larger than the wastewater treatment flow rate. Therefore, conventionally, the washing wastewater is temporarily retained in a storage tank, and is taken out in small quantities and mixed into the treated water of the fixed bed contact oxidation tank, and then processed in the subsequent turbidity separator. However, such a method requires a large-capacity storage tank in which the washing wastewater is temporarily stored, and a site must also be secured for it, which increases equipment costs and also requires consideration of measures against spoilage of the washing wastewater.

It is also conceivable that the turbidity separator installed after the fixed bed catalytic oxidation tank has a capacity that can directly treat washing wastewater, but this is not preferable as it would also increase equipment costs.

The present invention has been made in view of this point, and by providing a simple distribution tank and actively utilizing the wastewater retention tank provided before the fixed bed catalytic oxidation tank, it is possible to reduce the amount of water generated by cleaning. To provide an aerobic microbial treatment device capable of directly treating a large flow of washing wastewater containing turbidity with a turbidity separator provided for water passage without providing a storage tank exclusively for washing water.

That is, the present invention consists of a wastewater retention tank, a fixed bed contact oxidation tank, and a turbidity separator, and after the wastewater containing BOD components is temporarily retained in the wastewater retention tank, it is passed through the fixed bed contact oxidation tank to perform BOD treatment. Furthermore, in an aerobic microbial treatment device in which suspended matter in the treated water is removed by a suspended matter separator, a distribution tank is provided in the piping that communicates the fixed bed contact oxidation tank and the suspended matter separator, and the distribution tank and wastewater retention The tanks are connected via piping, and the cleaning wastewater generated when cleaning the fixed bed contact oxidation tank with a flow rate larger than the processing flow rate is treated as a part of the flow rate that is approximately equal to or smaller than the processing flow rate in the distribution tank. Part of the washing wastewater is passed through a turbidity separator as it is to separate the turbidity in the washing wastewater, and the remaining washing wastewater flows into a wastewater retention tank. This is an aerobic microbial treatment device.

The present invention will be explained in detail below based on the drawings.

The drawing is an explanatory flow diagram showing an example of an embodiment of the aerobic microorganism treatment device of the present invention, in which 1 is a wastewater retention tank, 2 is a fixed bed contact oxidation tank, 3 is a distribution tank, and 4
is a turbidity separator. Fixed bed contact oxidation tank 2
A support bed 5 is placed in the lower part, and gravel is placed on top of it.
A water distributor 7 has a filler layer 6 made of crushed stone or inorganic or organic molded material, and has a large number of small holes at the bottom of the support bed 5, and an air distributor 7 that similarly has a large number of small holes. 8 is installed, and while air bubbles are uniformly discharged from the air distributor 8, wastewater flows upwardly from the water distributor 7 and is deposited on the surface of the filler layer 6. The BOD components in the wastewater are biooxidized by the action of airborne microorganisms, and the treated water is taken out from the top. In some cases, wastewater may flow downwardly from the upper part of the filler layer 6, and treated water may be taken out from the lower part.

Further, the turbidity separator 4 shown in the drawing has a sludge scraper 10 disposed below the settling tank 9, and the scraper 10 is rotated slowly by a motor 11 to collect the precipitated sludge into the settling tank 9. This is a sedimentation system in which the clarified water is taken out from the lower part through the drainage pipe 12, and the clarified water is discharged from the upper part of the sedimentation tank 9.
As the turbidity separator 4, any device such as a pressure flotation separator or a filtration device that can separate turbidity and obtain clear treated water can be used.

In the present invention, the distribution tank 3 is provided in the connecting pipe 13 that communicates the fixed bed contact oxidation tank 2 and the turbidity separator 4, but the distribution tank 3 has an overflow weir 1 inside.
4 is attached, the treated water flowing out from the upper part of the fixed bed contact oxidation tank 2 flows into the overflow weir 14, and the treatment flow rate when biooxidizing wastewater does not overflow the overflow weir 14. The entire amount of water is sent to the turbidity separator 4 via the connecting pipe 13', and if the flow rate is larger than the flow rate for biological oxidation treatment of wastewater, only the amount of water corresponding to the excess flow rate is overflowed from the overflow weir 14. The wastewater is then sent to the wastewater retention tank 1 via the recycling pipe 15.

Next, the processing method of the aerobic microorganism processing apparatus of the present invention will be explained.

The wastewater 16 flows into the wastewater retention tank 1 and the wastewater is temporarily retained in the wastewater retention tank, but at this time, the blower 1
7 is driven to supply air through the air inlet pipe 18' and the air distributor 8', and agitate the air so that the accumulated wastewater does not become anaerobic.

Next, the wastewater in the wastewater retention tank 1 flows upward from the lower part of the fixed bed contact oxidation tank 2 via the pump 19, the wastewater inflow pipe 20, and the water distributor 7, and the air from the blower 17 is It flows into the lower part of the fixed bed catalytic oxidation tank 2 through the inflow pipe 18 and the air distributor 8 in the form of fine bubbles.

Since aerobic microorganisms are attached to the surface and voids of the filler layer 6, the BOD components in the wastewater 16 can be biooxidized by the action of the aerobic microorganisms, resulting in treated water with reduced BOD components. It can be obtained from the top of a fixed bed catalytic oxidation tank.

This treated water reaches the overflow weir 14 via the connecting pipe 13, but as mentioned above, at the flow rate when treating wastewater, it does not overflow the overflow weir 14 and the entire amount of the treated water reaches the turbidity separator 4. flows into.

The treated water is somewhat cloudy due to turbidity mainly composed of aerobic microorganisms that have gradually separated from the filler layer 6, but the turbidity settles to the lower part of the settling tank 9.
The clarified treated water is taken out from the treated water pipe 21.

As such treatment continues, the aerobic microorganisms that have grown on the filler layer 6 will enlarge as described above.
Since the filler layer 6 becomes clogged, the fixed bed catalytic oxidation tank 2 is cleaned as described later. That is, the drive of the pump 19 is stopped, and the pump 23 is driven to cause the wash water in the wash water layer 22 to flow from the lower part of the fixed bed contact oxidation tank 2 via the wash water pipe 24 and the water distributor 7. Note that the inflow flow rate of cleaning water is larger than the flow rate for treating wastewater, and is generally about twice the treatment flow rate. Also, as the washing water flows in, the blower 1
It is more effective to let the air from the air distributor 8 flow in from the air distributor 8, and it is preferable that the amount of air is larger than that during normal wastewater treatment.

Through such cleaning, the enlarged aerobic microorganisms that have grown on the filler layer 6 are exfoliated and become turbid.
The cleaning wastewater flows into the overflow weir 14 via the connecting pipe 13, but the cleaning wastewater with a flow rate approximately equivalent to the wastewater treatment flow does not overflow the overflow weir 14 and flows into the turbidity separator via the connecting pipe 13'. On the other hand, excess cleaning wastewater overflows from the overflow weir 14, flows into the wastewater retention tank 1 via the recycling pipe 15, and is diluted by the remaining wastewater. After the specified cleaning is completed, the above-mentioned process is continued again, but the cleaning wastewater that has flowed into the wastewater retention tank 1 is diluted by the wastewater remaining in the wastewater retention tank 1, Since it is further diluted by the inflowing wastewater 16, the treatment can be continued without clogging the fixed bed contact oxidation tank 2 with suspended matter.

In the present invention, since it is necessary to receive the entire amount of excess washing wastewater in the wastewater retention tank 1, the wastewater retention tank 1
The capacity of the drain must be at least larger than the total amount of overflowing washing wastewater, and preferably at least twice the capacity of the total amount of washing wastewater.

In addition, in the present invention, since excess cleaning wastewater flows into the wastewater retention tank 1, the wastewater retention tank 1 contains aerobic microorganisms separated from the filler layer 6, and therefore the wastewater retention tank 1 is It can be used as a pre-aeration tank and has the effect of improving the BOD removal ability of the entire device.

As explained above, the device of the present invention has a simple structure and provides a small distribution tank in the piping connecting the fixed bed contact oxidation tank and the turbidity separator, and also makes active use of the wastewater retention tank. , Washing wastewater with a flow rate larger than the processing flow rate can be directly treated with the turbidity separator installed in accordance with the processing flow rate, so the storage tank for washing wastewater that was conventionally required can be omitted, and the equipment The cost and installation area can be reduced, and the processing operation itself can be simplified.

[Brief explanation of drawings]

The drawing is an explanatory diagram of a flow showing an example of an embodiment of the aerobic microorganism treatment apparatus of the present invention. 1... Wastewater retention tank, 2... Fixed bed contact oxidation tank,
3... Distribution tank, 4... Turbidity separator, 5... Support bed, 6... Filler layer, 7... Water distributor, 8... Air distributor, 9...
Sedimentation tank, 10... scraper, 11... motor, 1
2...Sludge drain pipe, 13...Connection pipe, 14...Overflow weir, 15...Recycle pipe, 16...Wastewater, 17
... Blower, 18 ... Air inflow pipe, 19 ... Pump, 20 ... Treated water pipe, 21 ... Treated water pipe, 2
2...Washing water tank, 23...Washing water pump, 24...
...Cleaning water pipe.

Claims (1)

[Claims] 1 Consists of a wastewater retention tank, a fixed bed contact oxidation tank, and a turbidity separator. After the wastewater containing BOD components is temporarily retained in the wastewater retention tank, it is passed through the fixed bed contact oxidation tank for BOD treatment, and then In an aerobic microbial treatment device that removes turbidity from treated water using a turbidity separator, a distribution tank is provided in the piping that connects the fixed bed contact oxidation tank and the turbidity separation device, and the distribution tank and the wastewater retention tank are connected by piping. The cleaning wastewater, which has a flow rate larger than the processing flow rate generated when cleaning the fixed bed contact oxidation tank, is divided into a part of the flow rate that is approximately equal to or smaller than the processing flow rate in the distribution tank, and the remainder. The aerobic system is characterized in that it is configured such that a part of the washing wastewater is directly passed through a turbidity separator to separate the turbidity in the washing wastewater, and the remaining washing wastewater flows into a wastewater retention tank. Microbial treatment equipment.