JP2000301181A - Septic tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To almost eliminate the remaining of a chemical soln. for eliminating clogging of a membrane separator by providing a drawing means for drawing a stagnated chemical soln. to the membrane separator. SOLUTION: In a chemical soln. drawing means 3, a chemical soln. injection pump 19 being a pressure injection means 4 is reversely driven to forcibly such the chemical soln. held for a predetermined time in a membrane separator. The chemical soln. is forcibly drawn from the membrane separator by the drawing means 3 to almost eliminate the remaining of the chemical soln. in the membrane separator. Therefore, it can be avoided that microorganisms living in activated sludge within an aeration tank 8 are killed by excessive chlorine of the residual chemical soln. As a result, the lowering of treatment capacity by the charging of the chemical soln. can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a septic tank, and more particularly, to a method for greatly reducing the residual chemical solution for cleaning a membrane separation device and avoiding the use of a reducing agent for reducing the residual chemical solution.
Further, the present invention relates to a technique for rapidly injecting a chemical solution into a membrane separation device.

[0002]

2. Description of the Related Art Conventionally, in a purification tank in which a membrane separation device having a plurality of treatment membranes is immersed in a treatment tank, the clogging of the membrane separation device becomes a problem depending on the operation time. That is,
In the case of performing the membrane treatment by performing suction based on the water head pressure difference, if a clogging occurs in the membrane separation device, the membrane treatment stops. Further, in the case of performing film processing by suction by a pump, air is caught and the pump runs idle, causing a failure. Therefore, the clogging of the membrane separation device is dissolved with an aqueous solution of sodium hypochlorite (0.5%) to recover the head difference.

[0003]

In the past, however, a chemical solution was charged by its own weight. When the chemical solution is introduced by its own weight in this way, 3 liters of the chemical solution is required for each processing film, and in a five-person tank demonstration experiment, it takes about 15 to 30 minutes for the chemical solution to be introduced (slightly depending on how the processing film is clogged). ), Which takes about 15 minutes. or,
An aqueous solution of sodium thiosulfate (0.
5%) to treat residual chlorine. By using this reducing agent, it is possible to prevent excess chlorine from killing microorganisms living in the activated sludge in the aeration tank, and to prevent a decrease in treatment performance due to the introduction of a chemical solution.

As described above, in the related art, there is a problem that a reducing agent must be used in order to prevent the residual chlorine from killing microorganisms living in the activated sludge in the aeration tank. In addition, since the chemical solution is supplied by its own weight, it takes time to supply the chemical solution, and a large amount of the chemical solution flows to the aeration tank from a small portion, that is, the chemical solution does not pass from a large portion, that is, There was a problem that it was difficult to solve.

The present invention has been made in view of such a problem, and a chemical solution for eliminating clogging of a membrane separation device hardly remains, and the use of a reducing agent for reducing the remaining chemical solution is avoided. A purification tank capable of easily passing a chemical solution through a membrane separation device, eliminating clogging, and injecting a chemical solution into the membrane separation device in a short time. The task is to do so.

[0006]

According to a first aspect of the present invention, there is provided a purification tank in which a membrane separation device provided with a plurality of treatment membranes is immersed in a treatment tank. 1 is provided with a pull-out means 3 for pulling out the drug solution staying in 1. According to such a configuration, by forcibly extracting the chemical solution from the membrane separation device 1 by the extracting means 3, the chemical solution hardly remains in the membrane separation device 1, and excess chlorine is removed by the residual chemical solution. It is possible to avoid killing microorganisms living in the activated sludge in the inside, to prevent a decrease in treatment performance due to the introduction of a chemical solution, and to avoid the use of a reducing agent that reduces the residual chemical solution. it can.

[0007] The second aspect of the present invention is characterized in that a pressure injection means 4 for injecting a chemical solution into the membrane separation apparatus 1 by applying pressure when cleaning the membrane separation apparatus 1 is provided. According to such a configuration, since the chemical solution is injected into the membrane separation device 1 by applying pressure, the injection time of the chemical solution can be shortened as compared with the means for injecting the chemical solution by its own weight.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a schematic sectional view of a septic tank, and FIG. 1B is an explanatory view of a drawing means.

The septic tank A is, for example, an intermittent aeration type nitrogen removal type membrane separation / combination septic tank which performs aeration and an aeration stop in a single tank. Separation storage tank (also used as flow control tank) 5
And the organic matter concentration of the sewage is made uniform. Then, the effluent is transferred by a transfer pump 6 in the sewage transfer tank to a membrane separation intermittent gas tank 8 provided with a membrane separation device 1 as a secondary treatment tank 7 by a fixed amount. You. The membrane separation device 1 includes a large number of processing membranes 1a.
In the membrane separation intermittent gas tank 8, organic wastewater is biologically treated with activated sludge in the membrane separator 1, and solid-liquid separation is performed in the membrane separator 1. Further, the anaerobic state and the aerobic state are created by repeatedly stopping and operating the blower blower 9, and the nitrogen removal is performed by controlling the dissolved oxygen amount (DO) of the sewage in the tank. A sludge pulling pump (a lift pump) 10 is provided in the tank, and a certain amount of excess sludge is drawn into the impurity separation and storage tank 5 according to the setting of the control unit, and the MLSS (active sludge concentration) is constant. You are driving within the range. Reference numeral 11 denotes an air diffuser.

[0010] Each treatment membrane 1 is placed on the header 16 of the membrane separation apparatus 1.
are connected to the outlet pipe 12, and the outlet pipe 12 is provided with a discharge pump 13. The discharge pump 13 is discharged at a constant flow rate through the disinfection tank 15 according to the setting of the flow control valve 14.

A chemical solution supply pipe 17 extends from the header 16 and connects to a chemical solution tank 18. The chemical liquid tank 18 is provided with a chemical liquid injection pump 19 as the pressure injection means 4 so that a chemical liquid can be injected into the membrane separation device 1. The chemical liquid injection pump 19 includes various types such as a type that rotates a rotor, a type that uses a diaphragm, and a type that is a cylinder type shown in FIG. The chemical solution is, for example, a 0.5% by weight aqueous solution of sodium hypochlorite, and the injection speed of the chemical solution by the chemical injection pump 19 is about 2 to 3 L / min.
It is about 3 L per sheet. The drug retention time after injection is about 1
5 minutes. The injection is performed under such conditions. The injection of the chemical may be performed by a considerable difference in head.

[0012] In the conventional injection mode of injecting a chemical solution by its own weight, it took about 15 to 30 minutes.
According to the forced injection, it took about 10 minutes. In addition, because of the forced injection, the chemical solution can be injected to the dense portion of the processing film 1a or to the end portion where the chemical solution is difficult to spread, and the clogging can be easily eliminated.

FIG. 2B is an explanatory view, in which the chemical liquid injection pump 19 as the pressure injection means 4 is driven in the reverse direction to forcibly suck the chemical liquid held for a predetermined time in the membrane separation device 1. It is like that. In this manner, the structure is simplified by also serving as the chemical liquid pressure injection means 4 and the chemical liquid extraction means 3. The extracted chemical is discharged to the outside of the chemical tank 18 by switching the switching valve.
Reference numeral 21 denotes a bucket.

As described above, by forcibly extracting the chemical solution from the membrane separation device 1 by the extracting means 3, the chemical solution hardly remains in the membrane separation device 1, and excess chlorine is aerated by the residual chemical solution. It is possible to avoid killing the microorganisms living in the activated sludge in the tank 8, and it is possible to prevent a decrease in the treatment performance due to the introduction of the chemical solution. In addition, it is possible to avoid using a reducing agent that reduces the residual chemical solution, which has been conventionally used.

FIG. 2 shows the pressure injection means 4 and the extraction means 3.
And a cylinder form. Reference numeral 21 denotes a faucet, which is pulled out as needed and puts a chemical into the bucket 21.

In the present embodiment, the chemical liquid pressure injection means 4 and the chemical liquid withdrawing means 3 are combined, but may be configured differently.

[0017]

According to the first aspect of the present invention, there is provided a purification tank wherein a membrane separation device having a plurality of processing membranes is immersed in a processing tank.
Since the extracting means for extracting the chemical solution staying in the membrane separation device when washing the membrane separation device is provided, the chemical solution remains in the membrane separation device by forcibly extracting the chemical solution from the membrane separation device by the extracting means. Is almost eliminated, and excess chlorine can be prevented from being killed by activated chemicals in the activated sludge in the aeration tank by the residual chemical solution, and the treatment performance can be prevented from lowering due to the introduction of the chemical solution. There is an advantage that the use of a reducing agent that reduces the residual chemical solution can be avoided.

According to a second aspect of the present invention, a pressure injection means is provided for injecting a chemical solution into the membrane separation device by applying pressure when washing the membrane separation device. Therefore, there is an advantage that the injection time of the chemical solution can be shortened as compared with the means for injecting the chemical solution by its own weight.

[Brief description of the drawings]

FIGS. 1A and 1B show an embodiment of the present invention, in which FIG. 1A is a cross-sectional view, and FIG.

2A and 2B show another embodiment of the present invention, in which FIG. 2A is a schematic sectional view, FIG. 2B is an explanatory view at the time of withdrawing a chemical, and FIG. 2C is an explanatory view at the time of pressure injection.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing film 2 Processing tank 3 Extraction means 4 Pressure injection means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shin Shin, 1048, Kazuma, Kadoma, Osaka Prefecture, Matsushita Electric Works, Ltd. (72) Inventor Shigeyuki Yamaguchi 1048, Kazuma, Kazuma, Kadoma, Osaka, Japan Term (reference) 4D006 GA02 HA41 HA93 KA12 KA44 KB22 KB23 KC16 KD24 MA03 PA02 PB08 PC65 4D027 AB01 AB11

Claims (2)

[Claims] 1. A purifying tank in which a membrane separation device provided with a plurality of treatment membranes is immersed in a treatment tank, and provided with a pull-out means for pulling out a chemical solution retained in the membrane separation device when the membrane separation device is washed. A septic tank characterized by that. 2. The septic tank according to claim 1, further comprising pressure injection means for applying a pressure to the membrane separation device to inject a chemical solution during cleaning of the membrane separation device.