JPS61157306A - Method for washing hollow yarn membrane - Google Patents

Abstract

PURPOSE:To enable the washing of a hollow yarn membrane even at the stop period of filtering and during filtering operation, by withdrawing a filtered substance released by vibration due to external force from a liquid withdrawal port separately provided to the outside part of a hollow yarn membrane. CONSTITUTION:When the amount of a filtered substance adhered to a hollow yarn membrane became much by filtering waste water containing a suspended substance from a waste water supply tank 1 by a hollow yarn membrane module 4, valves 5, 18 are opened and air is supplied from a compressed air supply pipe 12 to impart vibration to the hollow yarn membrane to release the sedimented filtered substance. The released filtered substance is withdrawn to a high conc. waste liquidstorage tank 7 as the high conc. waste liquid of the suspended substance from a washing solution withdrawal pipe 9 to be separately treated. During this time, the washing of the hollow yarn membrane is performed while usual filtering is continued. A valve 4 of a treated liquid withdrawal pipe 8 is closed at the stop time of filtering operation to perform the same operation. After vibration was imparted to the hollow yarn membrane, air is withdrawn from the washing solution withdrawal pipe 9 along with the washing solution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for cleaning an external pressure type hollow fiber membrane filter. In particular, suspended substances contained in each wastewater
This invention relates to a method for cleaning a thread membrane filter in an external pressure type filter.

[Conventional technology]

Conventionally, when filtering a liquid to be treated using an external pressure type hollow fiber membrane filter, P:A substances accumulate on the outside of the hollow fiber membrane filter, increasing filtration resistance. Stop the flow of liquid, Pg: or condensate or these and pressure a! ! !
In the opposite direction to when filtering the liquid to be treated: j! JL liquid: Backwashing is performed.

However, when a high-concentration liquid to be treated is passed through tr, or when filtration is continued for a long time without backwashing even when filtering a low-concentration liquid to be treated, filtration that accumulates on the different surfaces of the hollow fibers may occur. There is a drawback that the amount of material is large and backwashing cannot fully remove it. In order to eliminate all of these drawbacks, backwashing should be performed frequently, but in this case, the filtration of the liquid to be treated will also have to be frequently stopped, which is not preferable.

[Structure of the invention]

The present invention relates to a method in which a hollow fiber membrane is used to pass a liquid to be treated from the outside to the inside of the hollow fiber membrane for P'A. A method for cleaning a hollow fiber membrane, characterized in that the material is sent to a highly concentrated liquid to be treated storage tank together with the liquid to be treated through a liquid outlet provided separately on the outside of the hollow fiber membrane. With this structure, the hollow fiber membrane can be cleaned not only when the filtration of the liquid to be treated is stopped or paused, but also while the filtration operation is being performed, and the problems of the above-mentioned prior art can be solved.

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

FIG. 1 shows a partial cross-sectional schematic diagram of an example of the apparatus used in the method of the present invention, in which reference numeral 1 denotes a W4N (liquid to be treated) supply tank, 2 a waste liquid supply pipe, 2' a waste liquid supply pump, 3 4 is a hollow fiber membrane module, 5 is! j!
Flow plate, 6F'X distributor, 7 is high concentration waste liquid storage tank, 8
1 is a processing liquid extraction pipe, 9 is a cleaning liquid extraction pipe, 10 is a cleaning water supply pipe, 11 is a backwash liquid extraction pipe, 12 is a pressurized air supply pipe, 15, 14, 15, 16, 17.18 is pulp, 1 ?
indicates an air vent pipe. In addition, each hollow fiber membrane module is
Consists of multiple hollow fiber membranes.

Wastewater containing suspended matter (water to be treated) is supplied downward from the wastewater supply tank 1 to the pump 2' via the distributor/4 to the bottom of the hollow fiber membrane filtration device, passing through the entire rectifier plate. After that,
The PR is treated by the hollow fiber membrane module, and is drawn out from the treatment liquid draw-out pipe 8 in the upper part of the filtration device, and is discharged after undergoing treatment such as neutralization if necessary. On the other hand, the r-filter adheres to the outer wall of the hollow fiber membrane.

If the amount of filtrate attached to the hollow fiber membrane increases and the filtration resistance becomes large, open the pulp 1st on the cleaning liquid extraction pipe 9 and simultaneously open the pulp 18 on the pressurized air supply pipe.
All cleaning of the hollow fiber membrane can be carried out while carrying out the necessary treatment. That is, the air supplied from the pressurized air supply pipe 12 is vibrated to the hollow fiber membrane in the process of rising upward in the hollow fiber membrane filtration device, and is applied to the hollow fiber membrane or between the hollow fiber membranes. Peel off the deposited filtrate. On the other hand, the separated sediment is suspended in the wastewater outside the hollow fiber membrane, becoming a highly concentrated waste liquid with a high concentration of suspended matter, and is then transferred from the cleaning liquid extraction pipe installed outside the hollow fiber membrane to the high concentration waste liquid storage tank. The waste is withdrawn to a storage facility, stored, and then processed separately. On the other hand, some of the waste liquid supplied to the hollow fiber membrane filtration device continues to be filtered during this time, so when using this method, the hollow fiber membrane can also be cleaned while continuing filtration. It's possible.

(9) When the operation is stopped or suspended, the hollow fiber membranes can be cleaned by closing the pulp 14t on the treatment liquid draw-out pipe 8 and performing all the same operations as above.

During a long-term stop or suspension of operation, after the cleaning is completed, the pulp 15i is closed on the waste liquid supply pipe 2, and the pulps 16 and 1 on the backwash water supply pipe 10 and the backwash liquid extraction pipe are closed.
The hollow fiber membrane can be completely washed by opening the tank at 7-7 and supplying backwash water. Also in this case,
The pressurized air supply pipe area air feed 9 can be cleaned efficiently by applying vibration to the hollow fiber membrane.

Incidentally, the air supplied to the pipe 12 to give vibration to the hollow fiber membrane is extracted together with the washing liquid from the washing liquid extraction pipe.

As described above, instead of sending air into the hollow fiber membrane filtration device as a means of imparting vibration to the hollow fiber membrane, the hollow fiber membrane may be fully irradiated with ultrasonic waves by an ultrasonic generator installed in the device. .

[Brief explanation of drawings]

FIG. 1 is a flow diagram of an apparatus for explaining the method of the present invention. 1. Waste liquid supply pipe, 2. Waste liquid supply pipe, 5. Hollow fiber membrane filtration device, 4. Hollow fiber membrane module, 7. High concentration waste liquid storage tank, 8. Processing liquid withdrawal pipe. 9. Cleaning liquid extraction pipe, 12. Pressurized air supply pipe

Claims (1)

[Claims] 1. In a method of passing a liquid to be treated from the outside to the inside of the hollow fiber membrane using a hollow fiber membrane for filtration, the hollow fiber membrane is vibrated by an external force, and the vibration is caused to vibrate the hollow fiber membrane. The filtrate that has been peeled off is
A method for cleaning a hollow fiber membrane, characterized in that the liquid to be treated is discharged together with a liquid to be treated from a liquid outlet separately provided on the outside of the hollow fiber membrane to a storage tank for a highly concentrated liquid to be treated. 2. The method for cleaning a hollow fiber membrane according to claim 1, in which the hollow fiber membrane is vibrated by supplying gas from the lower part of the filtration device or by an ultrasonic generator inserted into the filtration device. 3. A hollow fiber cleaning method according to claim 1 or 2, in which cleaning is performed while filtering the liquid to be treated. 4. A hollow fiber cleaning method according to claim 1 or 2, in which cleaning is performed when the filtration operation is stopped or suspended.