JPH04250900A - Biological treating device - Google Patents

Abstract

PURPOSE:To provide the biological treating device which allows the reduction of the size over the entire part of the device including a pollutant separating device, efficiently yields the clean treated water contg. suspended solids at a lower ratio and facilitates and maintenance. CONSTITUTION:The upper part of a fixed bed contact oxidation column 1 of a type open to the atm. copnstituted by packing materials 3, such as crushed stone, Rasching rings and hollow cylindrical nets, into the inside and the upper part of a filter column whcih is packed with erected long fiber bundles 11 consisting of the assemblies of the extremely fine monofibers in the entire part of the column and has extremely low fluid resistance are allowed to communicate with a connecting pipe 10. The water to be treated contg. the org. matter supplied to the lower part of the fixed bed contact oxidation column 1 by a supply pump 8 is passed in ascending flow in this column and is subjected to a biolongical treatment under an arm. pressure. This treated water is then introduced into the upper part of the filter column 9 via by a water level difference the connecting pipe 10. This treated water is passed in the descending flow from the top end toward the bottom end of the long fiber bundles 11 and is filtered by a gravitational system, by which the org. matter in the water to be treated is removed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a method for treating wastewater containing organic matter (organic wastewater), such as sewage and wastewater discharged from factories such as food factories and pulp and paper factories, under atmospheric pressure to attract aerobic microorganisms. BOD or COD and suspended solids (SS) in organic wastewater are removed by sequentially passing water through a fixed-bed catalytic oxidation tower having a bed of packing material for organic wastewater generation and a filtration tower using long fiber bundles as filter media. This relates to biological treatment equipment.

0002

BACKGROUND OF THE INVENTION In recent years, in the treatment of organic wastewater, catalytic oxidation towers, which are relatively easy to operate and manage, have been used in place of standard activated sludge treatment equipment. A layer of packing material in which aerobic microorganisms are grown is formed in the contact oxidation tower, and the water to be treated flows in an upward flow from the bottom of the packing material layer, and oxygen-containing gas such as air is introduced into the tower. There is a so-called fixed bed catalytic oxidation tower that performs biological treatment by introducing

Such a fixed bed catalytic oxidation tower usually performs biological treatment with the upper part of the tower open to the atmosphere, that is, under atmospheric pressure. It contains a relatively large amount of SS such as excess aerobic microorganisms separated from the water, and therefore a turbidity separator is required to remove this SS. A sedimentation separation tank is generally used as the turbidity separation device, but if clearer treated water is desired, a filtration tower filled with granular filter media such as sand or anthracite may be used. .

0004

[Problems to be Solved by the Invention] However, when a sedimentation separation tank is used as a turbidity separation device, there is a problem that a vast installation area is required. When using a filtration column filled with SS, there is a problem that if the particle size of the filter medium is reduced in an attempt to remove even the finest SS, the filtration speed cannot be increased, so it is not possible to downsize the device. If you increase the particle size of the filter medium to speed it up, fine SS
There was a problem in that it became difficult to capture the water, making it impossible to obtain clear filtered water.

[0005] The present invention solves the problems of the prior art described above, and makes it possible to miniaturize the entire device including the turbidity separator, and to efficiently obtain clear treated water with a low SS content. Moreover, it is an object of the present invention to provide a biological treatment device that is extremely easy to operate and manage.

[0006]

[Means for Solving the Problems] The present invention has been made to achieve the above object, and the present invention is directed to a fixed bed catalytic oxidation tower, which is open to the atmosphere, in the lower part thereof, and which has a packing layer for attaching aerobic microorganisms. , one end of the water inflow pipe having a supply pump is connected, and one end of the connecting pipe is connected to the upper part of the fixed bed catalytic oxidation tower, and the other end of the connecting pipe is connected to a long fiber bundle throughout the tower. One end of the filtrate outflow pipe is connected to the upper part of the filtration tower which is open to the atmosphere, and one end of the filtrate water outlet pipe is connected to the lower part of the filtration tower. At the same time, the treated water from the fixed-bed catalytic oxidation tower is introduced into the upper part of the filtration tower via a connecting pipe according to the water level difference, and the water is biologically treated under atmospheric pressure by flowing upward into the tower. This biological treatment device is characterized in that treated water flows downward into a filtration tower and is filtered by gravity.

[0007] The present invention will be explained in detail below based on the drawings. FIG. 1 is a flow explanatory diagram showing an example of an embodiment of the present invention, and numeral 1 in the figure is a fixed bed catalytic oxidation tower whose top is open so that biological treatment can be carried out under atmospheric pressure. The fixed bed catalytic oxidation tower 1 has a water-permeable support bed 2 in the lower part, and the upper part has gravel, crushed stone, porous ceramic, Raschig ring, Terraret packing, hollow cylindrical net, plastic mesh, and honeycomb tube. At the same time, an air distributor 4 to which an air inflow pipe 5 is connected and a water inflow pipe 7 to be treated are installed at the bottom of the support bed 2.
A water distributor 6 to which a water distributor 6 is connected is attached, and a feed pump 8 for supplying the treated water into the fixed bed catalytic oxidation tower 1 is attached to the treated water inflow pipe 7.

In the fixed bed catalytic oxidation tower 1 having the above structure, the water to be treated inflow pipe 7 is made to flow through the water inflow pipe 7 while the oxygen-containing gas such as air is made into bubbles and uniformly flows out from the air distributor 4 through the air inflow pipe 5. The water to be treated flows upward from the water distributor 6 through the filter, and the B in the water is absorbed by the action of aerobic microorganisms grown on the surface of the filler 3
Biologically oxidizes OD (or COD) components,
Treated water that has undergone biological treatment is taken out from a connecting pipe 10, which will be described later, and which communicates with the upper part of the fixed bed catalytic oxidation tower 1.

A filtration tower 9 open to the atmosphere is installed downstream of the fixed bed catalytic oxidation tower 1, and the upper part of the filtration tower 9 and the upper part of the fixed bed catalytic oxidation tower 1 are connected to each other. The treated water is communicated with the filter tower 9 through a connecting pipe 10 so that it can be introduced into the filter tower 9 depending on the water level difference.

[0010] Inside the filter tower 9, there is a fiber having a length of 0.4 to 3.0 m and a thickness of 10 to 100 μm, which is made of synthetic fibers such as acrylic fibers, polyester fibers, and polyamide fibers.
Long fiber bundles 11, which are preferably aggregates of ultrafine single fibers with a diameter of 20 to 45μ, are attached to a water-permeable support attached to the lower part of the tower at a filling rate of 30 to 150Kg/m2, preferably 50 to 75Kg/m2. 12, and the treated water of the fixed bed catalytic oxidation tower 1, which flows in through the connecting pipe 10 depending on the water level difference, is passed in a downward flow from the upper end of the long fiber bundle 11 toward the lower end to form a gravity-type oxidation tower. It is configured to filter to.

[0011] In the figure, reference numeral 13 indicates a water storage tank to be treated, and 14
, 15 are washing drain pipes connected to the upper part of the fixed bed catalytic oxidation tower 1 and the upper part of the filtration tower 9, 16 is a filtrate water outflow pipe connected to the lower part of the filtration tower 9, and 17 is also connected to the lower part of the filtration tower 9. 18 is an air inflow pipe branched and connected to the washing water pipe 17, 19 is a filtered water storage tank, and 20 to 23 are valves, respectively.

0012

[Operation] Next, the operation of the present invention will be explained using FIG. First, the valves 22 and 23 are closed, the supply pump 8 is driven, and the water to be treated containing organic matter in the water storage tank 13 is brought into contact with the fixed bed via the water inlet pipe 7, the valve 20, and the water distributor 6. While flowing from the lower part of the oxidation tower 1,
Oxidizing air is introduced in the form of fine bubbles through the air inlet pipe 5 and the air distributor 4. In addition, instead of air, oxygen-enriched air whose oxygen concentration is increased by treating the air with a gas selective permeation membrane or molecular sieve, or an oxygen-containing gas such as pure oxygen is flowed into the fixed bed catalytic oxidation tower 1. It's okay.

The inflowing water to be treated flows upward through the fixed bed catalytic oxidation tower 1 together with air bubbles, during which time it comes into contact with the layer of the packing material 3 on which aerobic microorganisms have grown under atmospheric pressure. Through this contact, organic matter contained in the water to be treated can be biooxidized by the action of aerobic microorganisms, and treated water with a reduced BOD concentration can be obtained from the upper part of the fixed bed catalytic oxidation tower 1.

Since the resulting treated water contains a large amount of suspended solids such as excess aerobic microorganisms that have separated from the filler 3, the treated water is passed through the connecting pipe 10 into the filtration tower 9 which is open to the atmosphere. The treated water is introduced into the filtration tower 9 by the water level difference between the fixed bed catalytic oxidation tower 1 and the filtration tower 9,
Therefore, no pump is required to transfer the treated water.

Inside the filtration tower 9, as mentioned above, a long fiber bundle 11 consisting of an aggregate of single fibers having a length of, for example, 0.4 to 3.0 m and a thickness of 10 to 100 μm stands all over the inside of the tower. It is set up. The treated water that has flowed into the filtration tower 9 flows down by gravity from the upper end of the long fiber bundle 11 toward the lower end, and during this time, in the voids formed by the long fiber bundle 11, the water contained in the treated water is filtered. SS is captured, and the filtrate flows out from the filtrate outflow pipe 16 via the water-permeable support 12.
It enters the filtered water storage tank 19.

Furthermore, the treated water of the fixed bed catalytic oxidation tower 1 that flows into the filtration tower 9 usually contains dissolved oxygen, and aerobic microorganisms separated from the packing material 3 in the fixed bed catalytic oxidation tower 1 are present. Since organic substances are present, biological treatment is performed in the filter tower 9 as well, and further removal of organic substances can be expected. In the filtration tower 9, the lower part of the long fiber bundle 11 is slightly bent due to the downward water flow at the initial stage of water flow, and its height is slightly reduced. The treated water from the fixed-bed catalytic oxidation tower 1 that has flowed therethrough passes by gravity from the upper end to the lower end of the upright long fiber bundle 11.

Furthermore, when the pressure loss in the filtration tower 9 increases due to continued water flow, the degree of bending of the long fiber bundle 11 at the lower part increases with the increase in pressure loss, but the degree of bending of the long fiber bundle 11 at the upper end of the long fiber bundle 11 increases. The phenomenon of bending does not occur until the end of the water flow, and the tips of the long fiber bundles 11 remain substantially vertical even at the end of water passage.

The gravity-type filtration tower 9 using the long fiber bundle 11 as described above has significantly less flow resistance than the conventional filtration tower using granular filter media such as gravel or anthracite.
Therefore, even in gravity filtration, the filtration rate (linear velocity; L
V) can be made as high as 20 to 50 m/H, and therefore the device can be made smaller. Incidentally, the filtration speed in conventional filtration towers using granular filter media such as gravel and anthracite is at most LV5 to 10 m/H.

While continuing the above-mentioned treatment, if the fixed bed catalytic oxidation tower 1 becomes clogged or the differential pressure in the filtration tower 9 rises to a predetermined value, the treatment is interrupted. Then proceed to the cleaning process as described below.

First, when cleaning the fixed bed catalytic oxidation tower 1, the supply pump 8 is stopped to interrupt the flow of water to be treated, and the valve 20 attached to the water inflow pipe 7 and the connecting pipe 10 are closed. The attached valve 21 is closed, and the oxidation tower 1 is further closed.
The valve 22 attached to the washing drain pipe 14 connected to the upper part of the pipe is opened.

Next, the water distributor 6 is connected via the cleaning water pipe 24 branched to the water inflow pipe 7 to be treated.
The cleaning water flows upwardly into the contact oxidation tower 1 through the air inflow pipe 5, or the cleaning air flows upward from the air distributor 4 through the air inflow pipe 5, and the cleaning air is deposited on the surface of the filler 3. Excess aerobic microorganisms are removed, and cleaning waste water containing a large amount of SS such as the removed aerobic microorganisms is discharged from the washing drain pipe 14.

Furthermore, when cleaning the filter tower 9 filled with the long fiber bundles 11, the valve 23 attached to the cleaning drain pipe 15 connected to the upper part of the filter tower 9 is opened, and the air inlet pipe 18 is drained from the air inflow pipe 18. Compressed air flows into the filter tower 9. Due to the inflow of the compressed air, the water in the filter tower 9 is stirred and the long fiber bundles 11 are vibrated, the voids formed between the fibers are destroyed, the SS aggregates are destroyed, and the long fiber bundles are The SS attached to 11 is peeled off.

[0023] While continuing the inflow of compressed air as described above, or with the inflow of compressed air stopped, washing water is introduced into the filter tower 9 from the lower part thereof through the washing water pipe 17. In the filtering tower 9, the lower end of the long fiber bundle 11 is fixed as described above, and the upper end is free, so that the long fiber bundle 11 becomes like a windsock due to the upward flow of the washing water. Each fiber vibrates as it stretches.
Therefore, the SS cannot remain in the long fiber bundle 11 and separates, and washing waste water containing a large amount of SS flows out from the washing drain pipe 15.

Although FIG. 1 shows a fixed bed catalytic oxidation tower or filtration tower in which the upper part of the tower is completely open,
The "atmospheric open type" used in the present invention does not necessarily mean only those with such a structure; in other words, the upper part of the tower is in communication with the atmosphere, and biological treatment is performed under atmospheric pressure or filtration treatment is performed under gravity. Any structure may be used as long as it can be performed according to the formula.

[0025]

[Effects] As explained above, according to the present invention, treated water containing SS flowing out from a fixed bed catalytic oxidation tower is filled with long fiber bundles made of aggregates of single fibers standing up in the tower. Since filtration is performed using a filtration tower with extremely low resistance, it is possible to perform filtration at a high flow rate such as LV = 20 to 50 m/H even with gravity filtration.As a result, the treated water of the fixed bed catalytic oxidation tower The entire device is smaller compared to conventional biological treatment equipment that uses a sedimentation separation tank and a filtration tower filled with granular filter media such as sand and anthracite as a turbidity separation device to remove SS contained in water. In addition, extremely clear filtered water with a low SS content can be obtained even when filtration is performed at a high flow rate.

Furthermore, since the present invention has a configuration in which the fixed bed catalytic oxidation tower and the filtration tower are operated under atmospheric pressure, the discharge rate of the water supply pump used is lower than when both towers are operated under pressure. It has the advantage that the pressure is low, the equipment cost is low, the power cost is low, and operation management is extremely easy.

[0027]

[Examples] Examples of the present invention will be described below. Diameter 30
A fixed-bed catalytic oxidation tower in which a synthetic resin hollow cylindrical net (trade name, Netron Pipe) was filled as a packing material in an open tower with a height of 2.0 m and a bed height of approximately 1.1 m. , in an open tower with a diameter of 10 cm and a height of 2.0 m, with a thickness of 3
A flow biological system as shown in Figure 1 is equipped with a gravity-type filtration tower filled with long fiber bundles consisting of aggregates of single fibers with a diameter of 5μ and a length of 1.5m at a packing rate of 75Kg/m2. BOD meat extract peptone in tap water using processing equipment
The water to be treated was treated in such a way that the amount of dissolved water was approximately 120 mg/l.

That is, the water to be treated is biologically treated by being supplied at a flow rate of about 160 l/H to a fixed bed catalytic oxidation tower in which aerobic microorganisms have been preliminarily grown on the surface of a cylindrical net, and then the water is biologically treated in the oxidation tower. The treated water was supplied to the filtration tower and subjected to filtration treatment. The BOD load at this time is 6.0Kg/m3.
On day one, the filtration rate was LV=20 m/H.

Further, if the fixed bed catalytic oxidation tower or the filtration tower became clogged while the above-mentioned treatment was continued, these towers were cleaned as appropriate. Table 1 shows the average processing results in steady state.

[0030]

[Table 1]

As can be seen from Table 1, even though the filtration rate in the filtration tower is as high as LV=20 m/H, an average BOD of 10 mg/H flows from the filtration tower outlet.
Very clean filtered water with SS of 5 to 8 mg/l was obtained.

[0032]

[Brief explanation of the drawing]

FIG. 1 is a flow explanatory diagram showing an example of an embodiment of the present invention.

[0033]

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Fixed bed catalytic oxidation tower, 2... Supported bed, 3... Filler, 4...
Air distributor, 5... Air inflow pipe, 6... Water distributor, 7... Water inflow pipe, 8... Supply pump, 9... Filtration tower, 10... Connection pipe, 11... Long fiber bundle, 1
2...Supporting bed, 13...Water storage tank to be treated, 14, 15...Washing drain pipe, 16...Filtered water outflow pipe, 17...Washing water pipe, 18...
Air inflow pipe, 19... Filtered water storage tank, 20-23... Valve, 24
…Cleaning water pipe

Claims (1)

[Claims] Claim 1: One end of a water inlet pipe having a supply pump is connected to the lower part of an air-open fixed bed catalytic oxidation tower having a packing material layer for attaching aerobic microorganisms; One end of the connecting pipe is connected to the upper part of the bed contact oxidation tower, and the other end of the connecting pipe is connected to the upper part of an air-open type filtration tower in which long fiber bundles are installed vertically throughout the tower. One end of the filtrate outflow pipe is connected to the lower part of the tower,
The water to be treated containing organic matter is flowed upward into the fixed bed catalytic oxidation tower by the supply pump and subjected to biological treatment under atmospheric pressure. A biological treatment device characterized in that the treated water is introduced into the upper part of the filtration tower by a water level difference through the filtration tower, and the treated water is caused to flow downward into the filtration tower and filtered by gravity.