JPH1133582A - Sewage treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exclude the contaminant bonded to the periphery of an air diffuser by washing the same with a chemical soln. to facilitate maintenance by arranging the air sending pipe connecting an air supply source and the air diffuser to an aerobic treatment bed and arranging a chemical soln. cylinder at a position higher than the liquid surface in the aerobic treatment tank. SOLUTION: A sewage treatment apparatus is equipped with an aerobic treatment tank 1 and the air diffuser 2 having air jet holes 3 formed thereto arranged to the bottom part thereof is connected to an air supply source 4 by an air sending pipe 5 and a chemical soln. injection pipe 7 is suspended from the chemical soln. cylinder 6 arranged on the aerobic treatment tank 1. After purifying treatment filtering sewage by the membrane module 9, a three-way cock 8 is changed over and the chemical soln. in the chemical soln. cylinder 6 is stored in the air sending pipe under the three-way cock 8 from the chemical soln. injection pipe 7. Subsequently, when the three-way cock 8 is again changed over in such a state that the air sending pipe 5 is filled with the chemical soln., the chemical soln. in the air sending pipe 5 is ejected from the air jet holes 3 along with air and the contaminant bonded to the periphery thereof is dissolved and removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sewage treatment apparatus for aerobically treating sewage.

[0002]

2. Description of the Related Art As a method for treating sewage, there is a biological treatment method utilizing an action of decomposing pollutants by organisms such as bacteria. The biological treatment method also includes an anaerobic bacterium which is decomposed by anaerobic bacteria which dislike oxygen. There are two types of treatment: aerobic treatment and aerobic treatment by aerobic bacteria requiring oxygen. Among these, in the aerobic treatment, an air diffuser is installed in the aerobic treatment tank, and bubble air is supplied into the aerobic treatment tank from a number of small air ejection holes formed in the diffuser. An operation of blowing and aerating is performed.

FIG. 3 shows an example of a conventional sewage treatment apparatus for performing such aerobic treatment. This sewage treatment device,
A diffuser b is installed at the bottom of the aerobic treatment tank a,
The air diffuser b is connected to the blower d by an air supply pipe e.
A plurality of air ejection holes c are formed on the upper surface of the air diffuser b.

[0004] Outside the aerobic treatment tank a, a chemical solution tube f containing a chemical solution (a cleaning agent such as sodium hypochlorite) and a chemical solution sending pump p are installed. Is connected to a chemical solution injection pipe h, and the chemical solution injection pipe h is a membrane module i for separating sludge and the like from aerobic treated wastewater.
Is connected to the inner surface of the

[0005] Further, in order to separate solids from the treated water after the aerobic treatment, a membrane module i is provided on the air diffuser b. A membrane filtration purification system for filtering water is performed.

The line for sending air from the blower d to the diffuser b and the line for sending the chemical in the chemical cylinder f to the membrane module i are different systems.

However, in the sewage treatment apparatus shown in FIG. 3, when the supply of air to the air diffuser b is stopped for maintenance, the sewage flows backward from the air ejection hole c to cause clogging. The air diffuser b may not function properly.

Further, even in a sewage treatment apparatus equipped with a membrane filtration and purification system such as a membrane module i, the viscosity of the sewage increases because the activated sludge is operated at a high concentration.
Even when air is constantly ejected from the air, clogging may occur due to sludge adhering to the air ejection holes c. In such a case, it is common practice to pull up the air diffuser b from the aerobic treatment tank a every several months to one year and clean the air ejection holes c with a brush or the like.

However, for that purpose, the air diffuser b must be pulled out of the aerobic treatment tank a every time maintenance is performed. In particular, in the case of the membrane filtration and purification system as shown in FIG. Since the air diffuser b is often arranged, it is extremely difficult to remove and pull up the air diffuser b.

Further, the work of rubbing the clogged air ejection holes c with a brush is troublesome and unsanitary, and is disliked by workers. Further, there is another inconvenience that a brush corresponding to the diameter of the air ejection hole c must be provided.

Further, also in the membrane filtration purification system, membrane clogging occurs when membrane filtration is continued for a long period of time. For clogging of the membrane, chemical cleaning for cleaning the membrane with a chemical is effective. For example, in Japanese Patent Publication No. 6-65371, membrane filtration is temporarily stopped and the membrane is filtered. A method called backwashing, in which a chemical solution is caused to flow in a direction opposite to the flow direction of the permeate to wash the inside of the membrane, is shown. (The sewage treatment apparatus shown in FIG. 3 can perform this backwashing.)

However, the membrane has high transmission resistance and
Since the water pressure due to the water depth acts, in order to pour the chemical solution into the inside of the membrane at a deep position for backwashing, as shown in FIG. It is necessary to inject the drug solution by applying a pressure of 1 kgf / cm ² or more by the pump p. Therefore, there is a problem that equipment costs, operation costs, maintenance costs, and the like are expensive.

[0013]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and eliminates the need for cleaning the clogging of the air ejection holes by pulling up the air diffuser every time maintenance is performed. It is an object to provide a processing device.

[0014] Further, even when the aerobic treated wastewater is filtered by the membrane filtration and purification method, there is no need to pull up the membrane module, and special equipment such as a liquid feed pump for backwashing the membrane module is required. It is an object of the present invention to provide a wastewater treatment device that does not use wastewater.

[0015]

According to the present invention, there is provided a sewage treatment apparatus having an aerobic treatment tank, comprising: an air supply pipe connecting an air supply source and a diffuser; It is characterized in that it is connected to a chemical liquid injection pipe connected to a chemical liquid cylinder placed at a position higher than the liquid level in the aerobic treatment tank.

Further, the invention is characterized in that the air supply pipe and the chemical injection pipe are connected via a switching valve.

In the present invention, the materials of the air supply pipe, the chemical liquid injection pipe, the switching valve, and the like are not particularly limited, but are preferably materials that are not easily deteriorated or deteriorated by sewage and a chemical liquid. polypropylene,
Examples include general-purpose synthetic resins such as ABS resin and FRP, and metal materials such as stainless steel and brass. As the chemical, a cleaning agent such as sodium hypochlorite is usually used.

A three-way cock of a manual, electric, pneumatic or the like is suitably used as the switching valve, and its installation position is preferably higher than the highest liquid level in the aerobic treatment tank.

(Operation) According to the first aspect of the present invention, the supply of air is stopped at the time of maintenance, and a cock below the chemical liquid cylinder is opened in place of the chemical liquid cylinder, and the level difference between the chemical liquid cylinder and the aerobic treatment tank is changed. Then, the chemical is allowed to flow naturally into the air supply pipe through the chemical injection pipe. Next, the cock below the liquid medicine cylinder is closed again, and when the supply of air to the air supply pipe is started, the liquid medicine in the air supply pipe is pushed out from the air ejection hole of the air diffuser by the air pressure.

As a result, contaminants such as sludge that has adhered and clogged around the air ejection holes of the air diffuser are removed by washing with a chemical solution, and the sludge adhering to the outer surface of the membrane module is removed. Contaminants such as are washed and removed from the outer surface of the membrane module with a chemical solution.

According to the second aspect of the present invention, by switching the switching valve, the switching between the chemical solution and the air can be easily performed by one operation, and automation is easy.

[0022]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic view showing an embodiment of the sewage treatment apparatus of the present invention, in which aerobic treatment is performed by aeration, and FIG. 2 shows a state in which aeration is stopped and cleaning with a chemical solution is performed.

The sewage treatment apparatus has an aerobic treatment tank 1, and an air diffuser 2 is installed at the bottom of the aerobic treatment tank 1.
The air diffuser 2 has, for example, a plurality of air ejection holes 3 formed on an upper surface thereof, and is connected to a blower (air supply source) 4 installed outside the aerobic treatment tank 1 by an air supply pipe 5. ing.

On the aerobic treatment tank 1, a chemical solution tube 6 containing a cleaning agent such as sodium hypochlorite is installed, and from the solution solution tube 6, a chemical solution injection pipe 7 is vertically installed. 5 and the chemical injection pipe 7 are connected via a three-way cock 8.
The three-way cock 8 is installed at a position higher than the highest liquid level HL of the aerobic treatment tank 1 and has a structure driven by an actuator (not shown).

On the air diffuser 2 in the aerobic treatment tank 1, a membrane module 9 is provided. A large number of hollow fiber membranes 91 of the membrane module 9 are
And a hollow fiber membrane 91 above and below the frame 92.
A module header 93 is provided to connect the upper and lower sides of the membrane filtrate, and the membrane filtrate is absorbed and discharged from the upper module header 93 by a pump.

Next, the operation of the sewage treatment apparatus will be described. In the state shown in FIG. 1, the air supply source 4 and the air diffuser 2 are connected to the three-way cock 8, and the chemical liquid injection pipe 7 is located at a position separated from the air supply pipe 5. The air supplied from the air supply source 4 passes through the air supply pipe 5 and becomes small bubbles from the air ejection holes 3 of the diffuser 2 and is ejected into the sewage,
Sewage is aerobic treated.

The sewage subjected to the aerobic treatment moves upward in the aerobic treatment tank 1 together with the air bubbles, passes through the membrane module 9 from the outer surface to the inner surface, is filtered, and is collected in the upper module header 93, not shown. It is sucked by the pump and discharged out of the aerobic treatment tank 1.

However, when the aerobic treatment tank 1 is operated for a long time, the sludge in the sewage adheres to the periphery of the air ejection hole 3 and the air ejection hole 3 is clogged. Also, the sludge adheres to the outer periphery of the membrane module 9 and is clogged.

Then, as shown in FIG. 2, the three-way cock 8 is switched to connect the chemical liquid injection pipe 7 to the air supply pipe 5 and disconnect the air supply source 4 from the air diffuser 2. Due to the level difference of the liquid level in the gaseous treatment tank 1, the chemical liquid injection pipe flows down naturally and accumulates in the air supply pipe 5 below the three-way cock 8. When the three-way cock 8 is switched to the previous position again in a state in which the chemical is almost completely filled in the air supply pipe 5, the chemical stored in the air supply pipe 5 is ejected from the air ejection hole 3 together with the air, and Particles of pollutants such as sludge that have adhered to the surroundings are dissolved and removed by the chemical solution, and clogging is cleaned.

The chemical liquid ejected from the air ejection holes 3 is
While rising in the aerobic treatment tank 1, the bubbles are sufficiently brought into contact with the outer surface of the membrane module 9 by the stirring action of the bubbles, and the attached pollutant particles are dissolved and removed, and the clogging is cleaned.

As described above, by using the above-mentioned sewage treatment apparatus, the membrane module 9 and the air diffuser 2 are pulled up every time maintenance is performed, and the clogging of the air ejection holes 3 is not cleaned with a brush. By switching the three-way cock 8 at the time, the clogging of the air ejection holes 3 of the air diffuser 2 and the membrane module 9 can be cleaned.

Hereinafter, specific embodiments of the present invention will be described. (Example 1) Using a sewage treatment apparatus having the structure shown in FIG. 1 and the following specifications, an experiment was conducted on clogging of an air diffuser and a membrane module and cleaning thereof. [Specifications of sewage treatment equipment] Aerobic treatment tank 1: volume 1 m ³ , water depth 1.8 m at maximum water level Diffuser 2: 20 air blow holes 3 made of vinyl chloride and 2 mm in diameter : Air volume 60 l / min Air supply pipe 5: Vinyl chloride pipe with 13 mm inner diameter Chemical liquid cylinder 6: Installed so that the chemical liquid level is 0.7 m above the maximum water level HL of the aerobic treatment tank 1, and the chemical liquid is sodium hypochlorite Chemical solution injection pipe 7: Vinyl chloride pipe with an inner diameter of 13 mm 3-way cock 8: Made of vinyl chloride with a diameter of 13 mm at each connection part, driven by an actuator, installed at 0.5 m above the maximum water level HL of the aerobic treatment tank 1

In the experiment, the amount of inflow into the aerobic treatment tank 1 was 1.
25 m ³ / day, the amount of permeated water in the membrane module 9 (=
The MLSS concentration in the aerobic treatment tank 1 was maintained at about 150 while maintaining the discharge flow rate from the aerobic treatment tank 1 at 1.25 m ³ / day.
It was set to be 00 mg / l and adjusted so as to maintain this value for 6 months.

After six months from the start of the experiment, the operation was stopped, the air diffuser 2 was pulled up, the number of clogged air ejection holes 3 was confirmed, and then the air diffuser 2 was installed in the aerobic treatment tank 1 again. did. Then, as shown in FIG.
The water level in the aerobic treatment tank 1 is lowered so that the liquid is exposed, the three-way cock 8 is switched, and the chemical in the chemical cylinder 6 is filled with the chemical injection pipe 7.
And the air supply pipe 5 below the three-way cock 8 was filled. Then, the three-way cock 8 is switched again to start the supply of air from the air supply source 4 to flush out the chemical solution in the air supply pipe 5 below the three-way cock 8, and to supply air for another 10 minutes. Stop the operation and pull up the air diffuser 2,
The number of clogging of the air ejection holes 3 was examined.

Thereafter, the water level was returned to the original state, the membrane module 9 was sucked, and sewage was permeated, and the suction pressure was measured.

As a result, the number of clogging of the air ejection holes 3 was 6 months after the start of the experiment, but no clogging was observed after the cleaning of the air ejection holes 3 with the chemical solution. In addition, the suction pressure of the membrane module 9 was −0.45 kgf / cm ² six months after the start of the experiment, but recovered to −0.12 kgf / cm ² after the cleaning of the membrane module 9 with the chemical solution.

(Comparative Example) An experiment on clogging and cleaning of the air diffuser and the membrane module was performed using the sewage treatment apparatus having the structure shown in FIG. In the comparative example, except that the cleaning of the air ejection port c was not performed by the chemical solution, and the chemical solution was injected from the inner surface of the membrane module i by the liquid feed pump p provided at the outlet of the chemical solution tube f to perform the cleaning. An experiment was basically performed in the same manner as in the example.

As a result, the number of clogging of the air ejection port c of the air diffuser b was 5 at 6 months after the start of the experiment. However, since this sewage treatment apparatus does not have a cleaning device for cleaning the air ejection holes c, the air ejection holes c were cleaned using a brush. Therefore, it took 25 minutes to clean the air ejection port c. Further, the suction pressure of the membrane module i six months after the start of the experiment was -0.47 kgf / cm < ² >, but after washing (backwashing) with a chemical solution for 10 minutes -0.15 kF.
gf / cm ² . However, electric power for operating the liquid feed pump p was required.

Table 1 summarizes the above results.

[0040]

[Table 1]

[0041]

According to the first aspect of the present invention, as described above, the membrane module and the air diffuser do not need to be pulled out of the aerobic treatment tank, and the time and man-hour for the cleaning operation are reduced. The operation can be greatly reduced, and unsanitary work of rubbing clogs with a brush is eliminated, thereby improving the working environment.

Also, due to the difference in liquid level between the chemical liquid cylinder and the aerobic treatment tank, the chemical liquid can flow naturally into the air supply pipe to clean the clogging of the air ejection holes of the air diffuser. Equipment costs including a liquid feed pump and the like for backwashing the membrane module are not required, and operation costs and maintenance costs for cleaning are also unnecessary.

According to the second aspect of the present invention, as described above, the switching between the air and the chemical can be easily performed in one operation and can be automated.

Further, there is no need to lift the membrane module and the air diffuser from the aerobic treatment tank, so that the time and man-hour for cleaning work can be greatly reduced, and unsanitary work of rubbing clogging with a brush can be avoided. And the working environment is improved.

Also, due to the difference in liquid level between the chemical liquid cylinder and the aerobic treatment tank, the chemical liquid can flow naturally to the air supply pipe to clean the clogging of the air ejection holes of the diffuser. Equipment costs including a liquid feed pump and the like for backwashing the membrane module are not required, and operation costs and maintenance costs for cleaning are also unnecessary.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of a sewage treatment apparatus of the present invention, in which aerobic treatment is being performed by aeration.

FIG. 2 is a schematic view showing an embodiment of the sewage treatment apparatus of the present invention, in which aeration is stopped and cleaning with a chemical is performed.

FIG. 3 is a schematic view showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aerobic treatment tank 2 Air diffuser 3 Air ejection hole 4 Air supply source 5 Air supply tube 6 Chemical liquid tube 7 Chemical liquid injection tube 8 Three-way cock 9 Membrane module 91 Hollow fiber membrane

Claims (2)

[Claims] 1. A sewage treatment apparatus provided with an aerobic treatment tank, wherein an air supply pipe connecting an air supply source and a diffuser, and a chemical liquid placed at a position higher than a liquid level in the aerobic treatment tank. A sewage treatment apparatus, wherein a chemical solution injection pipe connected to a cylinder is connected. 2. The sewage treatment apparatus according to claim 1, wherein the air supply pipe and the chemical liquid injection pipe are connected via a switching valve.