JPS6251126B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes ion-exchange fibers as a super-assistant to reduce the amount of leakage from the cladding and the amount of leakage from the ion-exchange fibers at the initial stage of water sampling. Regarding processing method.

A pre-coat filter forms a thin pre-coat layer containing powder of a super-aid (pre-coat material) on a filter element or screen in advance, thereby removing fine suspended substances and, if necessary, ions in the liquid to be passed through. It is something. As super-aids, diatomaceous earth, fiber powder, asbestos, sand,
Anthracite, powdered ion exchanger, etc. are used.

Recently, powdered ion-exchange resins have been used as auxiliary agents in precoat filters, but the flow rate inside the filter drops rapidly compared to inside the piping, making it easier for flocs to grow again, especially at high concentrations. This tendency becomes more pronounced as more pre-coated material is used. Ion exchange fibers have been used in place of such powdered ion exchange resins, and ion exchange fibers have the following advantages over ion exchange resins. That is, (1) good backwashing performance and less clogging of the filter element; (2) There is no need to add an electrolyte for adjusting the cohesive force between ion exchangers. That is,
In the case of powdered ion-exchange resins, unless the super-aid concentration during pre-coating is extremely low, the electrolyte must be added in order to form a good pre-coated layer or to prevent the pre-coat differential pressure from rising sharply, which is seen when pre-coating with powdered cation-exchange resin alone. However, in the case of ion-exchange fibers, there is no need to add electrolytes unless they are used in combination with an ion exchanger having a different type of ion-exchange ability. (3) The differential pressure upon completion of pre-coating is small. (4) The stirring and mixing time in the pre-coat tank etc. before pre-coating can be shortened. In other words, with powdered ion exchange resin, 10
Although stirring and mixing for about 20 minutes is required, with ion-exchange fibers, precoating can be started as soon as the fibers are uniformly dispersed in water (several seconds is sufficient).

Ion-exchange fibers have the above-mentioned advantages, but depending on the selection of the over-element, there is a lot of leakage from the over-element during pre-coating, and it accumulates in areas where it tends to accumulate due to the structure, which can cause problems especially during sampling. At the initial stage, a lot of water flows downstream,
Furthermore, even when the flow rate changes suddenly, a large amount of water flows downstream.

The present invention was made in view of the current situation, and its purpose is to solve the above-mentioned drawbacks, use ion-exchange fiber as a super-aid, and reduce the amount of leakage from the cladding and the ions at the initial stage of water sampling. It is an object of the present invention to provide a method for treating overflow liquid using a precoat filter, which can reduce the amount of leakage of exchange fibers.

To summarize the present invention, the method for treating a surcharged liquid according to the present invention includes a method for treating a surcharged liquid using a pre-coat filter, in which cation exchange fibers or anion exchange fibers are used as superimposing agents, and cellulose fibers or It is characterized in that it is used in combination with synthetic fibers.

According to the present invention, by using the above-mentioned combination method, the amount of leakage of crud (an insoluble component suspended in water, mainly iron oxide) and the amount of leakage of ion-exchange fibers, especially at the initial stage of water sampling, can be significantly reduced. be able to. Furthermore, the increase in differential pressure when passing through the liquid to be passed through can be significantly reduced compared to when conventional powdered ion exchange resins are used, and the rise in differential pressure due to dirt on the passing element can be almost eliminated. Therefore, the reproducibility of precoating is extremely good.

In the present invention, as a method of combining the above, (a)
(b) precoated with a mixture of cation exchange fibers or anion exchange fibers and cellulosic fibers or synthetic fibers as a super-aid;
First, cellulose fibers or synthetic fibers are precoated as a super-auxiliary agent, and then cation exchange fibers or anion exchange fibers are precoated (overcoated).

The type of cationic or anionic exchange fiber, cellulose fiber or synthetic fiber in the present invention is not particularly limited, and commercially available fibers can be used as appropriate. In other words, cation- or anion-exchange fibers include derivatives of fibers, such as cellulose fibers, which have ion-exchange properties by introducing various dissociative substituents, and are usually about 10 to 50 μm in diameter and 50 to 50 μm in length. 100μm
It is appropriate to set it at a certain level. As an ion exchange fiber, a carbon fiber made from polyvinyl alcohol with anion and cation exchange groups introduced has been developed, and its excellent performance (high ion exchange rate and regeneration rate, low flow resistance of processing liquid) In this case, it is possible to manufacture products with a diameter of about 20 to 50 μm and a length of about 250 to 1500 μm.

In addition, cellulose fibers are short cellulose fibers such as purified high-purity wood pulp, and are chemically stable and have a fairly small differential pressure, so using them can reduce the amount of leakage from the cladding. be able to. Examples of such cellulose fibers include SOLKA FLOCK BW100 (SOLKA
-FLOC, manufactured by Brown Company) and KC FLOC W-50, W-100 (manufactured by Sanyo Kokusaku Pulp Company)
Commercially available products such as can be applied. The dimensions of these cellulose fibers are expressed in terms of the mesh size and the amount that passes through the mesh, and in the present invention, it is appropriate that the amount that passes through a 50 to 100 mesh sieve is 90% or more, and those with dimensions less than this range are used. If used, the pressure loss will be large, and if it exceeds this range, it is undesirable in terms of the amount of leakage from the cladding, etc.

In addition, as synthetic fibers, for example, leversorb
Polyacrylonitrile fibers such as AF2 (Lewasorb, manufactured by Bayer Japan) can be applied, with a diameter of about 25 to 50 μm and a length of about 25 to 50 μm.
It is appropriate to have a size of about 50 to 600 μm from the viewpoint of adjusting the differential pressure over time and reducing the amount of leakage from the cladding.

Further, the amount of cellulose fiber or synthetic fiber used in the present invention is not particularly limited, and since the differential pressure of ion exchange fiber alone is extremely low, it can be arbitrarily selected, but as in the case of powdered ion exchange resin, Range of 1/4 to 1 for ion exchange fibers, and usually
Approximately 1/2 is enough effect (Improved crud removal performance)
can demonstrate.

In addition, the amount of these surfactants used varies depending on the applied filter element (generally, there are cylindrical, leaf-shaped, and horizontal types), but for example, in the case of using the Johnson screen described later, the concentration of Weight% or less (dry basis), precoat material (superior agent) amount approximately 1Kg/m ² (dry basis), precoat LV value approximately 5.5m/hour (=840/
(time) and is completed in about 10 to 15 minutes of pre-coating time.

Next, embodiments of the present invention will be specifically described with reference to the drawings, but the present invention is not limited thereby.

The filter element used in this example is cylindrical, and the specifications of the Johnson screen as a filter screen are (1) 1 piece, (2) opening width 50 μm (slot No. 2), and (3) outer diameter 48.6 mm. , (4) length 1m, and (5) excess area ^0.153m2 . In addition, the super-aiding agent used was
(1) H-type strongly acidic cation exchange fiber (carbon fiber made by heating polyvinyl alcohol thread, immersed in concentrated sulfuric acid to introduce sulfone groups, diameter 30 μm)
m, length 500 μm, (2) Polyacrylonitrile synthetic fiber (manufactured by Bayer Japan, Levasorb
AF2, diameter 25-50 μm, length 50-600 μm), (3) Cellulose fiber No. 1 (manufactured by Sanyo Kokusaku Pulp Co., Ltd., KC
(4) Cellulose Fiber No. 2 (manufactured by Sanyo Kokusaku Pulp Co., Ltd., KC Flotsu W-100, which passes 90% or more through a 100 mesh sieve). there was.

FIG. 1 is a schematic diagram showing a specific example of the apparatus used in the present invention, in which 1 is a raw water tank, 2 is a pump, 3 is a backwash tank, 4 is a precoat filter,
5 is a flow meter, 6 is a precoat tank, 7 is a stirrer, and 8 is a desalination tower.

The main body of the precoating device 4 is made of acrylic resin (inner diameter 101 mm, outer diameter 120 mm), and the precoating state can be visually confirmed.

During the test, the system was first put into a holding state, and a predetermined amount of super-aid was put into the pre-coat tank 6 and stirred by the stirrer 7. Next, the system is put into the precoat state, and the precoat LV value (the value obtained by dividing the flow rate by the excess area) is set to 5.5 m/hour (=840/hour) by adjusting the valve while watching the flow meter 5. Precoating was carried out for about 15 minutes under the conditions of 0.7% by weight (dry basis) and an amount of precoat material (superior agent) of 1 kg/m ² (dry basis).

Then, the system is put into the holding state again,
The holding LV value was set to 2.43 m/hour (=370/hour) by adjusting the valve while watching the flow meter 5. Thereafter, the water sampling state continued, and the water sampling LV value was set to 2.43 m/hour (=370/hour) by adjusting the valve while watching the flowmeter 5.

Next, we simulated the electrolytes (ions) in the actual solution.
NaCl and Fe ₃ O ₄ simulating cladding were supplied.
(Simultaneous supply after about 5 minutes after pre-coating is completed)
In addition, timely sampling was performed using a Millipore device.

Next, the supply of electrolyte and cladding was stopped to put the system in a holding state, and backwashing was performed and the backwash was received in the backwash receiving tank 3.

The results obtained by the above method (changes over time in the clad concentration, the ion exchange fiber concentration, or the total concentration of both at the outlet of the precoat filter) are shown in FIGS. 2 to 4. The concentration of crud (based on iron) at the inlet of the precoat filter 4 was 280 ppb, and the electrical conductivity at the inlet was 4 μs/cm. That is, Fig. 2 is a graph showing the change over time in the cladding concentration ratio (vs. synthetic fiber) at the outlet of the precoat filter, and Fig.
The figure is a graph showing the change over time in the ion-exchange fiber concentration ratio (versus synthetic fibers) at the outlet of the pre-coat filter, and Figure 4 shows the total concentration ratio of clad and ion-exchange fibers (versus synthetic fibers) at the outlet of the pre-coat filter. It is a graph showing changes over time, where A is a case where a mixture of synthetic fibers and ion exchange fibers is precoated (dry weight ratio: synthetic fibers/ion exchange fibers = 1/2), and B is a case where synthetic fibers are precoated first. When precoating and then precoating ion exchange fiber (dry weight ratio: synthetic fiber/ion exchange fiber =
1/2), C is the case where cellulose fiber No. 1 is precoated first and then ion exchange fiber is precoated (dry weight ratio: cellulose fiber No. 1).
1/ion exchange fiber = 1/2), D is the case where cellulose fiber No. 2 is precoated first and then the ion exchange fiber is precoated (dry weight ratio:
Cellulose fiber No. 2/Ion exchange fiber = 1/
2), E indicates the case of using only ion exchange fiber.

In each figure, the vertical axis represents how many times the crud concentration at the outlet of the pre-coat filter was compared to when pre-coating with synthetic fiber alone, which remained almost constant during the test, and the horizontal axis represents Represents the time after electrolyte and cladding supply. Further, as mentioned above, the cladding is based on iron, and the ion exchange fiber is based on drying.

As is clear from Figure 2, the cladding concentration can be increased by precoating a mixture of ion exchange fibers with synthetic fibers, or by precoating synthetic fibers or cellulosic fibers first and then precoating the ion exchange fibers. It was reduced by about 1/2.
Furthermore, as is clear from FIG. 3 (D is almost the same curve as C), the leakage of the ion exchange fiber itself was reduced to about 1/10 or less shortly after water was collected. Furthermore,
As is clear from FIGS. 3 and 4, especially B,
As shown in C and D, the effect was great when overcoated with ion exchange fibers. In addition,
In this test, the leakage of the cellulosic fibers or synthetic fibers themselves was negligible.

In addition, the increase in differential pressure was about 1/5 of that when the precoating conditions were constant using a powdered cation exchange resin and synthetic fiber mixture (dry weight ratio: 4:1) (A
~ E). In addition, when powdered cation exchange resin is used, the dirt on the over-element becomes noticeable and the pressure difference can be more than 10 times that of the above-mentioned good pre-coating. The reproducibility of precoating is good, and there is almost no increase in differential pressure across the over-element. Although the anion exchange fibers were inferior to the cation exchange fibers in crud removal performance, the ion exchange fibers themselves had the same leak prevention ability.

As explained above, according to the present invention, ion-exchange fibers are used as a super-assistant, and the ion-exchange fibers are mixed with cellulose fibers or synthetic fibers and precoated, or the cellulose fibers or synthetic fibers are precoated first. By subsequently precoating (overcoating) with ion-exchange fibers, it is possible to reduce the amount of leakage of the clad during treatment of the overflowing liquid, and especially the amount of leakage of ion-exchange fibers at the initial stage of water collection.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a specific example of the device used in the present invention, Fig. 2 is a graph showing changes over time in the crud concentration ratio (vs. synthetic fibers) at the outlet of the precoat filter, and Fig. 3 is a graph showing the change over time in the crud concentration ratio (vs. synthetic fibers) at the outlet of the precoat filter. A graph showing the change over time in the ion-exchange fiber concentration ratio (vs. synthetic fiber) at the outlet of the precoat filter. This is the graph shown. 1... Raw water tank, 2... Pump, 3... Backwash tank, 4... Pre-coat filter, 5... Flow meter, 6... Pre-coat tank, 7... Stirrer, 8
...Desalination tower.

Claims (1)

[Scope of Claims] 1. A method for treating a surcharged liquid using a precoat filter, characterized in that cation exchange fibers or anion exchange fibers and cellulose fibers or synthetic fibers are used together as a filter aid. How to dispose of spilled liquid. 2 Cation exchange fiber or anion exchange fiber,
2. The method for treating a filtrated liquid according to claim 1, wherein a mixture with cellulosic fibers or synthetic fibers is used as an assisting agent. 3. A method for treating a filtrated liquid according to claim 1, which comprises first precoating cellulose fibers or synthetic fibers as a super-assistant, and then precoating cation-exchange fibers or anion-exchange fibers as a super-assistant. .