JPH0217925A - Method for backwashing hollow yarn membrane filter apparatus - Google Patents

Abstract

PURPOSE:To effectively remove a solid by preventing the lowering of the liquid level during a backwashing process by intermittently performing scrubbing action and filling a container with water during the intermittent stoppage of scrubbing. CONSTITUTION:Hollow yarns 1 are suspended in a filter container 8and a liquid to be treated is allowed to flow through the hollow yarns 1 from the outside toward the interiors thereof. In regenerating the hollow yarns 1 by removing the solid adhered to the outer surfaces of the hollow yarns 1, a vent pipe 11 is opened at a definite liquid level in order to lower the liquid to be treated in the container 8. Next, backwashing air is supplied from a compressed air pipe 10 and, thereafter, scrubbing action is applied from the lower part of the container 8 by a scrubbing air pipe 12 and, subsequently, the liquid at the time of backwashing is discharged out of the container through a drain pipe 13. In this case, the aforementioned scrubbing action is performed intermittently and the container 8 is filled with water during the intermittent stoppage of scrubbing. As a result, the removal of a solid can be effectively performed.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention relates to hollow fiber m's used for liquid treatment such as water and wastewater in industrial plants such as thermal power plants and nuclear power plants. The present invention relates to a backwashing operation method for regenerating a hollow fiber filtration membrane of a filtration device.

(Prior art) Hollow fiber membrane filtration devices generally have a pore size of 0 as shown in Figure 3.
．． This is a liquid filtration device using hollow fibers 4 having a structure in which a bore 1 of about 1 μm penetrates from an outer surface 2 to an inner surface 3, and the hollow fibers 4 are made of an organic material.

To explain the filtration principle of the hollow fiber 4 having such a structure, as shown in FIG. It captures solid matter 5 in the liquid. Clear filtrate F2
flows out from the inner surface of the hollow fiber 4 and can filter the processing liquid F1 containing solids.

The hollow fibers 4 made of organic material have mechanical characteristics such as flexibility, high strength, and a small pore diameter of 0.1 μm. Furthermore, although it has the physical characteristic of allowing liquids such as water to pass through but not allowing gases such as air to pass through, it also has the disadvantage that it deteriorates when left in organic substances such as oil or the air for a long time, and loses the above-mentioned physical characteristics.

Additionally, hollow fibers are very expensive due to their special structure.

A conventional example of a hollow fiber membrane filtration device is shown in FIG.

The hollow fibers 4 are made into a hollow fiber module 6 in which tens of thousands of fibers are bundled in order to increase the filtration area, increase the amount of processing a, and downsize the fibers. Several to several dozen hollow fiber modules 6 are attached to the tube plate 7 depending on the condition of the processing liquid. This tube plate 7 is stored in a storage container 8.

A processing liquid inlet pipe 9, a filtrate outlet/pressurized air pipe 10, a vent pipe 11, a scrubbing air pipe 12, and a discharge/liquid filling pipe 13 are attached to the storage container 8, and each pipe has a filtrate outlet valve v1. , processing liquid population valve v2, vent valve v3,
Pressurized air valve v4, scrubbing air valve v5, exhaust, liquid valve v
6 and a liquid tension valve v7 are attached.

While the hollow fiber membrane filtration device is in use, the treatment liquid population valve V213 and the filtrate outlet valve v1 are fully opened to filter the treatment liquid F1 containing solids, but the treatment liquid F1 containing solids continues to flow. As a result, the amount of solid matter adhering to the outer surface of the hollow fibers increases and the filtration area of the hollow fibers decreases. That is, clogging occurs, resulting in a reduction in processing capacity and an increase in differential pressure, which impairs performance. Furthermore, if left as is, equipment damage such as damage to the hollow fibers will occur, causing serious problems in plant operation. Furthermore, damage to the hollow fibers may result in significant economic losses. Therefore, in order to prevent such failures and losses, the hollow fibers are regenerated periodically or depending on the state of the differential pressure between the processing liquid inlet and the filtered liquid outlet.

A conventional reproduction method will be explained with reference to FIGS. 5 and 6.

First, the filtrate outlet valve v1 is fully closed. After confirming that the filtrate outlet valve v1 is fully open, the treated liquid artificial valve v2 is fully opened to disconnect the filtration device from the system. Next, the vent valve v3 is fully opened to relieve pressure from the processing liquid section.

After that, confirm that the vent valve v3 is fully open, and then fully open the pressurized air valve v4 to supply pressurized air F3 to the upper chamber 1 of the storage container 4.
In addition to step 4, the liquid in the upper chamber 14 is caused to flow from the inside of the hollow fiber to the outside, and the solid matter adhering to the outer surface of the hollow fiber is removed by a flow opposite to the normal flow. By this operation, approximately 40 to 60% of the solid matter adhering to the outer surface of the hollow fibers is removed. In order to more completely remove the attached solids, the scrubbing air valve v5 is fully opened after the predetermined pressurization time t1 has elapsed, and scrubbing air F4 is applied to the hollow fibers from the scrubbing air pipe 12 to vibrate the hollow fibers. Shake off any solids left behind. This scrubbing removes almost 100% of the solid matter adhering to the outer surface.

After the predetermined scrubbing time t2 has elapsed, the scrubbing air valve v5 is fully closed, and the drain valve v6 is fully opened to discharge the sludge-containing wastewater in the lower chamber 15.

After the time t3 necessary for discharge has elapsed, the drain valve v6 is fully closed, and the liquid filling valve v7 is fully opened to fill the lower chamber 15 and the upper chamber 14 with liquid. After the liquid filling time t4 has elapsed, the liquid filling valve 7 is fully closed.
fully open. Through this series of operations, the hollow fibers are regenerated.

As mentioned above, hollow fiber Il! Iil! The performance of the filtration system is maintained by repeatedly sampling and regenerating water.

(Problem to be Solved by the Invention) However, as shown in FIG. 6, in the past, the backwashing process was performed with the scrubbing air valve v5 fully open, so the pump-up effect of the scrubbing air caused the inside of the lower chamber 15 to The processing liquid is discharged along with the air through the vent pipe 11, causing a drop in the level of the processing liquid during the regeneration period, as shown in FIG. This leaves solid matter attached to the hollow fibers, resulting in poor regeneration. If water is collected under such conditions, it will be necessary to regenerate it frequently, resulting in a decrease in operating efficiency and a shortened lifespan of the hollow fibers, resulting in large economic losses.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for backwashing a hollow fiber membrane filtration device that can prevent a drop in the liquid level during the backwashing process and effectively remove solids. With the goal.

[Structure of the invention]

(Means for Solving a Problem) The present invention is a hollow fiber membrane filtration device in which a hollow fiber is suspended in a filtration container and a treatment liquid is caused to flow from the outer surface of the hollow fiber to the inner surface of the hollow fiber. When removing solid matter adhering to the outer surface of the hollow fiber and regenerating the hollow fiber, the vent pipe is opened at a certain level of the processing liquid to prevent the processing liquid in the container from decreasing, and air is supplied for backwashing. A method in which a scrubbing action is performed from the bottom of the container after the completion of the washing process, and then the backwashing liquid is discharged out of the container via a drain pipe, in which the scrubbing action is performed intermittently, and the scrubbing is stopped intermittently. It is characterized by filling the container with water.

(Function) According to the present invention, by shortening the scrubbing time to remove solid matter adhering to the hollow fibers and alternately performing scrubbing and liquid tensioning, the liquid level in the chamber decreases due to scrubbing. is immediately supplemented and maintained at a nearly constant liquid level during backwashing.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

Incidentally, since the hollow fiber + am filtering device used in this embodiment is the same as that shown in FIG. 5, FIG. 5 will be used as is in the description of this embodiment.

In this embodiment as well, the filtrate outlet valve v1 is fully opened when entering the regeneration process. Next, the treatment liquid population valve v2 is fully opened to disconnect the hollow fiber membrane filtration device from the treatment liquid supply and drainage system. After that, first, the vent valve V3 is fully opened, and the pressurized air valve V4 is fully opened to cause the liquid in the upper chamber 14 of the hollow fiber membrane filtration device to flow back, and to remove solid matter adhering to the outer surface of the hollow fiber. . After the pressurization time t1 has elapsed, the scrubbing air valve v5 is fully opened and scrubbing air F4 is supplied from the scrubbing air pipe 12 into the lower chamber 15. The hollow fibers are then vibrated with scrubbing air to shake off solid matter remaining on the outer surface. After the scrubbing time t2 has elapsed, the scrubbing air valve v5 is fully opened. In this case, the scrubbing time t2 is a time that is sufficiently short compared to the total time required for scrubbing and in which the liquid level in the lower chamber 15 does not decrease significantly due to the pump-up effect of scrubbing.

Then, the liquid tension valve v7 is fully opened and the liquid is replenished into the lower chamber 15 for the necessary liquid replenishment time t5, and then the liquid tension valve v
7 is fully opened. After confirming that the liquid tension valve v7 is fully open, the scrubbing air valve v5 is fully opened for a scrubbing time t2, and then the scrubbing air valve v5 is fully opened.

After confirming that the scrubbing air valve v5 is fully open,
7 is fully opened for a fluid replacement time t5, and then the liquid filling valve v7 is fully opened.

In this way, the scrubbing operation by opening and closing the scrubbing air valve v5 and the fluid replacement operation by opening and closing the liquid tension valve v7,
The scrubbing is repeated alternately for the total time required for scrubbing to remove solids left on the hollow fibers.

Thereafter, the pressurized air valve v4 is fully closed, and the drain valve v6 is fully opened to discharge the contaminated liquid in the lower chamber 15. After the elapse of the evacuation time t3, the evacuation valve v6 is fully opened. Drain valve V6
After fully opening, the liquid filling valve v7 is fully opened to fill the hollow fiber membrane filtration device with liquid. After the liquid filling time t4 required for liquid filling has elapsed, the liquid filling valve v7 is fully closed, and the regeneration process is completed.

Thereafter, if necessary, the treatment liquid population valve v2 is fully opened and the filtrate outlet valve v1 is fully opened to perform the filtration action.

According to the above embodiment, during the regeneration process of the hollow fiber membrane filtration device, by alternately repeating the scrubbing performed to remove solids by the scrubbing operation performed during backwashing, and the liquid filling (replacement liquid), As shown in Figure 2,
A drop in the liquid level within the lower chamber 15 can be minimized. Therefore, not only can the hollow fibers be efficiently regenerated, but also deterioration of the hollow fibers can be sufficiently prevented.

〔Effect of the invention〕

As described above, according to the present invention, by performing the scrubbing action intermittently and filling the container with water during the scrubbing, it is possible to prevent the liquid level from decreasing during the backwashing process. Solids can be removed effectively.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing one embodiment of the present invention, FIG. 2 is an explanatory diagram showing the state of the liquid level in the chamber according to the above embodiment, and FIG.
The figure is an enlarged view showing the membrane cross section of the hollow fiber membrane to be backwashed, Figure 4 is a view showing the state of solid matter adhering to the hollow fiber membrane, Figure 5 is a configuration diagram showing the hollow fiber membrane filtration device, FIG. 6 is a process diagram showing the backwashing effect according to the conventional method, and FIG. 7 is an explanatory diagram showing the state of the liquid level in the chamber according to the conventional method. DESCRIPTION OF SYMBOLS 1...Hollow fiber, 5...Solid substance, 8...Container, 11
...vent pipe, Fl...processing liquid, F4...scrubbing air. Figure Figure

Claims (1)

[Claims] A hollow fiber membrane filtration device in which hollow fibers are suspended in a filtration container and a processing liquid is distributed from the outer surface of the hollow fibers to the inner surface thereof, and the solid matter adhering to the outer surface of the hollow fibers is removed. When regenerating the hollow fiber, the vent pipe is opened at a constant level of the processing liquid in order to reduce the processing liquid in the container,
In a method in which a scrubbing action is performed from the bottom of the container after the supply of air for backwashing ends, and then the liquid during backwashing is discharged to the outside of the container via a drain pipe, the scrubbing action is performed intermittently, and A method for backwashing a hollow fiber membrane filtration device, characterized by filling a container with water during intermittent stops of scrubbing.