JPH1147629A - Method for evaluating separation performance of suspended solids - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To evaluate the separation performance of suspended solids, which evaluates the separation performance of low-particles without being affected by high-particles, in evaluating the separation performance of suspended solids. provide. In evaluating the separation performance of a suspended substance,
A method for evaluating the performance of separating suspended substances, wherein suspended particles having an average particle diameter of 1 μm or more and 5 μm or less are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to the present invention, wherein the average particle size is from 1 to 1.
In the performance evaluation of filtration means for the purpose of removing particles of 10 μm, by using particles having a particle diameter in the range of 1 to 5 μm as a suspended substance, evaluation is performed while clearly grasping the characteristics of the filtration means. The present invention relates to a method for evaluating the performance of separating suspended substances.

[0002]

2. Description of the Related Art A woven fabric having a lattice structure based on a so-called ternary weave of flat, twill, and satin is widely used as a filter medium for filtering suspended substances in water. Tokiko Sho 62-13
Japanese Patent Publication No. 046 and Japanese Patent Publication No. 2-47244 disclose a filter cloth obtained by raising a woven fabric using ultrafine fibers for the weft and forming nap of the ultrafine fibers on the surface. Further, as a filter medium having a fiber bundle on the surface, Japanese Utility Model Publication No. Hei 5-34730, Japanese Utility Model Publication No. Hei 4-14112, and Japanese Patent Application No. 6-3047.
The filter and the filter cloth described in No. 05 are known.

In purifying river water and groundwater with these filter cloths, relatively large particles contained in raw water are caught and adsorbed on the surface of the filter cloth and become clogged. Tends to reduce the amount of treated water. In other words, since what is called a pre-filter is formed on the surface of the filter cloth, there is a problem that the original performance of the filter cloth is hardly exhibited. Using a filter cloth,
Conversely, when purifying swimming pool water or bathing water, which has a relatively low concentration of suspended solids and a small particle size, the removal of suspended solids tends to be reduced due to the difficulty of forming a pre-filter-like layer. Can be seen. As described above, since there is a difference in the filtration performance depending on the properties of the target raw water, it is inevitable to grasp the performance of the filter cloth using the standard evaluation raw water, but the standard evaluation raw water so far has an appropriate particle size distribution. Since no turbid matter was found, it tended to be affected by the large particle size.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a method for evaluating the separation performance of suspended particles, which is not influenced by high-particles, and evaluates the separation performance of low-particles. It is an object to provide a method for evaluating separation performance.

[0005]

Means for Solving the Problems In view of the above circumstances, the present inventors have made various studies, and as a result, have found that the problem can be solved by the following method. That is, in evaluating the separation performance of a suspended substance, the average particle diameter is 1 μm or more and 5 μm or more.
It has been found that by using suspended particles of m or less, the accurate performance of the filtration means can be evaluated.

Furthermore, it has been found that fine minerals such as kaolin or formazine prepared from hydrazine sulfate and hexamethylenetetramine are most suitable as suspended particles.

That is, according to the present invention, in evaluating the performance of separating suspended substances in water using a filtration means, suspended particles having an average particle diameter of 1 μm to 5 μm are used. Is a method for evaluating separation performance.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically.

[0009] As the filtering means used in the present invention, it is preferable to use a filtering cloth made of cloth, and furthermore, a filtering cloth made of ultrafine fibers having a filtering layer of 0.1 to 10 µm. Examples of such a filter cloth include a filter cloth obtained by raising a woven fabric using microfibers for the weft and forming nap of the microfibers on the surface, and more preferably a filter cloth having a fiber bundle on the surface. Examples of the filter cloth having a fiber bundle on the surface include a filter cloth in which one end or a part of an ultrafine fiber bundle is integrated with a base layer made of a woven fabric as a root. Examples of the method of integrating the microfine fiber bundle with the base layer include, but are not limited to, bonding with an adhesive, heat fusion, ultrasonic bonding, entanglement of the yarn and fiber bundle of the base layer, and a combination thereof. It is not something to be done.

In the present invention, the fibers that can be used for the ultrafine fibers constituting the filtration layer are composed of a polymer substance having a fiber forming ability, and include nylon 6, nylon 66, nylon 12,
Polyamides such as copolymerized nylon, aromatic polyamides,
Polyesters such as polyethylene terephthalate and copolymerized polybutylene terephthalate, polyolefins such as wholly aromatic polyesters, polyethylene and polypropylene, polyurethane, polyacrylonitrile, polyvinyl chloride, polyvinyl alcohol, vinyl polymers, polyvinylidene chloride, polyhydrosulfite, and polyolefin Ethylene fluoride, copolymerized polyfluoroethylene, polyoxymethylene and the like. Further, composite fibers having a core-sheath structure, a multi-core-sheath structure, a sea-island structure, a bimetal structure, or the like in which a plurality of these polymer substances are combined, and combinations of fiber types are also used according to the purpose. The thickness of the fiber is more preferably 10 μm or less, which is relatively thin, and more preferably 0.1 to 9 μm to improve the performance of the fine particles.
In order to improve the fineness of the fine particles while maintaining high durability of the fiber, the thickness is more preferably 1 to 8 μm.

In the present invention, the suspended substance for evaluating the separation performance of the filtration means has an average particle diameter of 1 to 5 μm.
It is preferable to use fine particles of the above. Such fine particles include fine minerals derived from rock, silica, alumina,
Examples include inorganic fine particles such as iron oxide and diatomaceous earth, and organic fine particles such as activated carbon, carbon black and formazine.

The rock-derived fine minerals include, for example, kaolinite, decittite, nacrite, halloysite, other fine clay of the kandite group, montmorillonite,
Fuller's earth, bentonite, saponite and other fine clays of the smectite group, talc, mica and mineral residues which make up a substantial proportion of these clays are mentioned. Examples of the inorganic fine particles include silica, alumina, barium sulfate, calcium carbonate, and aluminum hydroxide.
Examples of the organic fine particles include activated carbon, carbon black, latex particles, and formazin. Among them, use of formazine is a particularly preferred method. Formazin is prepared from hexamethylenetetramine and hydrazinium sulfate, but has good dispersibility and stability in water, and is particularly used in Europe and the United States as a calibration standard solution for measuring turbidity of water. Formazin has a particularly sharp particle size in water of 1 to 5 μm in weight distribution (measured by a Coulter Multisizer (manufactured by Coulter)), and is particularly suitable for evaluating the low particle size performance of a filter cloth using ultrafine fibers. Are finding that.

Hereinafter, the present invention will be described more specifically with reference to Examples, but it should not be construed that the invention is limited thereto.

[0014]

【Example】

(Example 1) A fabric is formed by using a 250 denier, 48 filament yarn of polyethylene terephthalate as a warp and a weft as a yarn (F1) of a base layer, and a polyethylene terephthalate as a fiber bundle (F2) of a filtration layer. False twisting was performed on a yarn of 240 denier and 576 filaments, and a false twisted yarn having a crimp rate of 27% was used. By arranging F2 at a fixed ratio with respect to the number of warp yarns F1, a double woven fabric composed of two upper and lower same woven fabrics was prepared. This woven fabric is a double woven fabric in which F2 repeats reciprocating between two upper and lower woven fabrics separated by a predetermined interval. F2 is one in which the wefts of the upper and lower fabrics are integrated alternately with the entanglement points.

In the obtained integrated double fabric, the fiber bundle of F2 is sliced in parallel with the surface of the fabric at a designated position in the thickness direction, so that the surface of the filter layer is in contact with the free end of the fiber bundle of F2. Woven fabric. At this time, the length of the fiber bundle of F2 was 8.0 mm. Next, pass these fabrics between the rotating brush roll and back roll, brush the fiber bundles in the direction where the fiber bundles are naturally slightly inclined, and open the fibers. The fibers were spread all over, and at the same time, the directions of the fibers were aligned. Subsequently, the surface of the opened fiber bundle was pressed against the surface of the heated metal roll with tension, and the fiber bundle was set to produce a filter cloth. The filtration performance of the filter cloth thus obtained was evaluated. The evaluation was performed based on the rejection calculated from the change in the number of SS particles before and after filtration (hereinafter referred to as a number average rejection) and the rejection calculated from the change in SS weight before and after filtration (referred to as the weight average rejection). Here, SS is an abbreviation of suspended solids (Suspended Solids), and is generally a component that is filtered through a 1 μm-cut filter paper and remains on the filter paper.

The number average rejection was calculated from the following equation by measuring the number of particles present in a unit volume of each of raw water and filtered water before and after filtration using a Coulter Multisizer (manufactured by Coulter). The weight inhibition rate was measured with reference to JIS factory drainage test method, JIS-K0102.

That is, as shown in FIG. 1, a filter cloth 2 is attached between the upper filter 1 and the lower filter table 4, and is fixed with a metal clamp 6, and then the pressure is reduced from the suction bottle 7 side to 250 mmH. _The raw water was filtered with a pressure difference of ₂ O to obtain a filtrate. Millipore A
The solution was filtered through a P1 μm cut filter paper (manufactured by Nippon Millipore), the absolute dry weight was measured, and calculated from the following equation.

Number average rejection (%) for each particle size = 1− (A / B) × 100 (1) where A: number of particles contained in filtered water B: number of particles contained in raw water Weight Average rejection (%) = 1-{(b′-a ′) / (ba)} × 100 (2) where a: filter paper weight before filtering raw water (g) a ′: filtered water Filter paper weight before filtration (g) b: Paper weight containing residues of raw water (g) b ': Paper weight containing residues of filtered water (g) Also, average of standard substances in the raw water for evaluation The particle size was measured using a Coulter Multisizer (manufactured by Coulter Inc.).

Evaluation raw water was prepared in the following procedure.

This is a general method for preparing a formazin solution.
ASTM (1984) D (1889-81 Standard Test Methods
for TURBIDUTY OF WATER "1984 Annual Book of ASTMSta
ndards ", Vol 11.01, 268-274, ASTM, Philadelphia) and JIS K 0101 (Industrial water test method, 13-18), that is, hydrazine sulfate 1.00.
0 g is placed in a volumetric flask, and purified water is added to make a total amount of 10 g.
0 ml was used as solution A. Separately, 10.00 g of hexamethylenetetramine was placed in a 100 ml volumetric flask, and purified water was added to make the total amount 100 ml. Next, 5 ml each of solution A and 5 ml each of solution B were added to a measuring flask 100 m.
After mixing at 25 ± 3 ° C. for 24 hours,
Purified water was added to make a total volume of 100 ml, which was used as a formazin stock solution. This stock solution was diluted 20-fold with purified water to obtain about 10
mg / l of raw water was prepared.

Table 1 shows the average particle diameter and turbidity of raw formazine water, Table 2 shows the weight average rejection and the turbidity of the treated water after filtration with a filter cloth, and FIG. 2 shows the number average of each particle diameter of formazin particles. The rejection rate was shown.

(Example 2) The filtration performance of the following raw water was evaluated using the filter cloth prepared in Example 1.

10.0 g of kaolin and 0.2 g of sodium pyrophosphate decahydrate were stirred with 1.5 l of purified water for exactly 5 minutes at 4000 rpm using a homomixer, and further purified water was added to make 10 l. The stock solution was used.
This stock solution was about 1000 mg / l, and was diluted 100 times to obtain 10 mg / l stock water.

Table 1 shows the properties of the raw water, Table 2 shows the results of evaluating the filtration performance of the filter cloth using the raw water, and FIG. 2 shows the number average rejection.

(Comparative Example 1) The filtration performance of the following raw water was evaluated using the filter cloth prepared in Example 1.

10 g of diatomaceous earth (Radiolite # 100 (manufactured by Showa Kagaku Kogyo) is collected in a 2 L beaker, and purified water 1.
5 l was added and stirred at 4000 rpm for exactly 5 minutes, and purified water was further added to make a total of 10 l. 10 L of this solution
The particles were transferred to a lower bottle and allowed to stand for 10 minutes to precipitate high-particle-size particles, and a supernatant liquid of 5 cm or more was taken out from the bottom and used as a standard stock solution. This standard stock solution was diluted with purified water to give 3 mg / l
Raw water. The properties of the raw water and the filtration performance of the filter cloth are shown in Table 2 and FIG.

The weight-average rejection shows almost the same value when formazin is used as when diatomaceous earth is used as a standard substance. However, focusing on the rejection (number-average rejection) for each particle size, it can be seen that the rejection in the lowest particle size range is highest when the filter cloth is evaluated with raw water using formazine as a standard substance. Although the details of this phenomenon are unknown, formazin has a relatively narrow particle size distribution,
When grasping the rejection of particles having a particle size of 0 μm or less, the rejection for each particle size could be evaluated more clearly than other standard substances. It is considered that the effect of the small particle size is small.

[0028]

[Table 1]

[Table 2]

[0029]

With the above arrangement, the present invention has an effect that the performance of separating small particles can be evaluated without being affected by high particles.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus used for a separation performance evaluation method of the present invention.

FIG. 2 is a graph showing the particle diameter and the number average rejection of each standard substance shown in Examples.

[Explanation of symbols]

 1: Upper filter 2: Filter cloth 3: Filter cloth support stand 4: Lower filter stand 5: Rubber stopper 6: Metal clamp 7: Suction bottle 8: Measuring cylinder

Claims (6)

[Claims] (1) In evaluating the separation performance of a suspended substance,
A method for evaluating the performance of separating suspended substances, wherein suspended particles having an average particle diameter of 1 μm or more and 5 μm or less are used. 2. The method for evaluating the separation performance of a suspended substance according to claim 1, wherein a filter cloth made of a cloth is used as the filtering means for evaluating the separation performance of the suspended substance. 3. The method for evaluating the performance of separating suspended substances according to claim 2, wherein the filter cloth is a cloth having a filter layer made of ultrafine fibers of 0.1 to 10 μm. 4. The method according to claim 1, wherein the suspended particles are made of a fine mineral. 5. The method according to claim 4, wherein the fine mineral is kaolin. 6. The method according to claim 1, wherein the suspended particles are formazine.