JP2002320975A - Equipment and method for water treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment equipment and a method therefor which, in the water treatment to coagulate and eliminate prescribed components in raw water, generates agglomerates in a stable PH condition, fully prevents generated agglomerates from being crushed, and efficiently and surely supply treated water with turbidity and chromaticity being sufficiently reduced. SOLUTION: The water treatment equipment according to this invention is characterized in that the equipment comprises a line mixer 2a which produces mixed water by putting a coagulant and a PH conditioner into raw water, an introduction part 9 to introduce mixed water, a cylindrical filtration tank 7 on the top of which a coagulation part 10 is installed to hold and convert mixed water into condensed water, a fiber filtration means 3 which is equipped with a fibrous material 8 installed in the lower part of the filtration tank 7, a measurement instrument which measures turbidity or chromaticity of treated water discharged from the fiber filtration means 3, and a controller 13 which controls adding quantities of coagulant and PH conditioner to be charged into the line mixer 2a in accordance with turbidity or chromaticity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water treatment apparatus and method, and more particularly, to a treatment apparatus for reducing turbidity and chromaticity of raw water when performing water purification treatment using river water or the like as raw water. And methods.

[0002]

2. Description of the Related Art In purifying water using river water, lake water, dam water, industrial water, sewage treated water, etc. as raw water, it removes suspended matters and suspended matters in the raw water and removes turbidity and chromaticity. For the purpose of reduction, for example, a water treatment apparatus shown in FIG. 2 is used.

In the apparatus shown in FIG. 2, first, a coagulant is added to raw water in a mixing tank 19 to obtain mixed water.
Next, a pH adjuster is added in the flocculation tank 20 to obtain flocculated water containing a flocculent of suspended matter and suspension in the mixed water.
The coagulated water is supplied from the coagulation tank 20 by the pump 21 to the filtration means 3.
And the aggregate (produced floc) is removed by the filter 8 'to obtain treated water.

[0004]

However, in the above-mentioned conventional water purification treatment, since a stirring tank such as a mixing tank or a flocculating tank is used when adding a flocculant or a pH adjuster, the water purifying property is poor. The pH of the water to be treated (mixed water, coagulated water) after the addition of the modifier is likely to fluctuate, and predetermined components in the mixed water may not be stably coagulated. Also, if a pump is used as a liquid sending means for sending the coagulated water from the coagulation tank to the filtration means, the coagulated matter in the coagulated water is crushed by the pump, so that it is difficult to sufficiently filter the coagulated matter in the filtration step. Becomes Therefore, in the treated water obtained by the conventional water purification treatment, the turbidity and chromaticity may not be sufficiently reduced.

[0005] The present invention has been made in view of the above-mentioned problems of the prior art, and in a water treatment for aggregating and removing predetermined components in raw water, aggregates are formed under stable pH conditions. It is an object of the present invention to provide a water treatment apparatus and a method capable of sufficiently preventing crushing of generated aggregates and efficiently and surely obtaining treated water with sufficiently reduced turbidity and chromaticity.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above-mentioned object, that is, the water treatment apparatus of the present invention is characterized in that a coagulant and a pH adjuster are injected into raw water and mixed. A line mixer for introducing water, an introduction section for introducing the mixing water, and a cylindrical filtration tank provided with an aggregation section for holding the mixing water for a predetermined time and forming aggregation water, and a lower section of the filtration tank. And a fibrous filtration means provided with a fibrous body disposed in the fiber.

Further, the water treatment method of the present invention comprises a mixing step of adding a coagulant and a pH adjuster to raw water passing through a line mixer to obtain mixed water, and a cylinder having an introduction portion and a coagulation portion provided at an upper portion. In a fiber filtration means comprising a filtration tank having a shape and a fibrous body disposed at the lower part of the filtration tank, mixed water is introduced from the upper part of the filtration tank, and the mixed water is held for a predetermined time in the aggregation section. And a fiber filtration step of immersing the fibrous body in the condensed water to filter the condensed water to obtain treated water.

In the present invention, a line mixer is used as a means for mixing raw water, a flocculant, and a pH adjuster, and the mixed water is held for a predetermined time in a flocculation section provided above a filtration tank of the fiber filtration means. Thereby, crushing of the aggregate can be sufficiently prevented. Further, by using a line mixer, the followability is improved, and a predetermined component can be aggregated under a stable pH condition. Therefore, by the water treatment apparatus and method of the present invention, it is possible to efficiently and reliably obtain treated water in which turbidity and chromaticity are sufficiently reduced.

The turbidity according to the present invention indicates the degree of turbidity of water. Turbidity corresponding to turbidity when 1 mg of standard kaolin is contained in 1 liter of purified water is 1 degree (or 1 degree).
mg / l).

[0010] The chromaticity according to the present invention refers to the degree of yellowish to yellowish brown exhibited by soluble substances and colloidal substances contained in water. The chromaticity of 1 degree corresponds to the coloration when 1 liter of purified water contains 1 mg of platinum (Pt) in potassium chloroplatinate and 0.5 mg of cobalt (Co) in cobalt chloride. The chromaticity represented by the colorimetric method is a visual comparison with the yellowish color in the standard row, and the chromaticity in the transmitted light measurement method is a comparison of the yellowish color with an absorbance of 390 nm.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
In the drawings, the same or corresponding portions are denoted by the same reference characters.

FIG. 1 is a schematic configuration diagram showing a preferred embodiment of the water treatment apparatus of the present invention. The water treatment apparatus 1 shown in FIG. 1 has line mixers 2 a and 2 b and fiber filtration means 3, which are connected by a flow path 4. Container 5
The a contains a flocculant and the container 5b contains a pH adjuster. The flocculant can be injected into the line mixer 2a and the pH adjuster into the line mixer 2b and mixed with raw water. The addition amount of the flocculant and the pH adjuster is
The desired value can be set by the valves 6a and 6b.

The fiber filtration means 3 includes a cylindrical filtration tank 7 and a fibrous body 8 disposed below the filtration tank 7.
An introduction section 9 and a flocculation section 10 are provided at an upper portion of the filtration tank 7, and the mixed water introduced into the filtration tank 7 from the introduction section 9 is held in the flocculation section 10 for a predetermined time. Further, by immersing the fibrous body 8 in the coagulated water, the aggregates in the coagulated water can be removed.

The treated water thus obtained is sent from the fiber filtration means 3 to the filtration treatment tank 11. A measuring means 12 is provided in a flow path between the fiber filtration means 3 and the filtration water tank 11, and the turbidity and / or chromaticity of the treated water is measured by the measuring means 12. The measuring means 12 is a control means 13
And a measurement data signal relating to the turbidity and / or chromaticity of the treated water from the measuring means 12 to the control means 13, and the coagulant and / or the pH adjusting agent to the valves 6 a and 6 b from the control means 12. Control signals relating to the addition amount are sequentially sent, and the addition amount of the flocculant and / or the pH adjuster is adjusted based on the turbidity and / or chromaticity of the treated water.

In the case of performing water treatment using the water treatment apparatus having the above configuration, first, a coagulant and a pH adjuster are added to raw water in line mixers 2a and 2b to obtain mixed water.

The coagulant used in the present invention is not particularly limited as long as it can coagulate predetermined components such as suspended solids and suspensions in raw water.
Iron-based coagulants such as ferric chloride (FeCl ₃ ), inorganic coagulants such as aluminum sulfate (Al ₂ (SO ₄ ) ₃ ), and polymer-based coagulants such as polyaluminum chloride (PAC) Agents are preferably used. The amount of the coagulant to be injected into the raw water is appropriately selected according to the turbidity and chromaticity of the raw water.

Note that p of the raw water before adding the iron-based flocculant is
When H exceeds 5.8, an acid such as sulfuric acid is added to the raw water in addition to the coagulant, and the pH is adjusted to 5.8 or less. In addition, since aluminum sulfate is easily dissolved in an acid such as sulfuric acid, when an acid such as sulfuric acid is added to raw water, it is preferable to use ferric chloride as a coagulant.

In the present invention, mixed water having a predetermined pH is obtained by further adding a pH adjuster to the raw water after the addition of the flocculant. The pH of the mixed water is not particularly limited as long as a predetermined component in the mixed water can be sufficiently coagulated. However, when an iron-based coagulant is used, the optimum pH is 5.8, Agent (aluminum sulfate, PA
C) is 7 to 7.5.

The pH adjusting agent used in the present invention is not particularly limited. For example, sodium hydroxide (caustic soda, NaOH) is added to raw water whose pH is adjusted to 5.8 or less by adding ferric chloride and sulfuric acid. By adding, a mixed water having a desired pH can be obtained.

FIG. 1 shows two line mixers 2.
Although an example of the water treatment apparatus provided with a and 2 was shown, the number of line mixers used in the present invention is not particularly limited as long as the coagulant and the pH adjuster can be added, and at least one line mixer is used. May be.

Next, the mixed water is supplied to the filtration tank 7 of the fiber filtration means 3.
And is held for a predetermined time (preferably 60 to 300 seconds) in the aggregating section 10 above the filtration tank 7, whereby a predetermined component in the mixed water is agglomerated into aggregated water. At this time, when the mixed water flows in, for example, spirally from the inlet 9 at the upper part of the filtration tank 7 along the circumferential direction of the filtration tank, the coagulation efficiency of a predetermined component in the mixed water is improved. At the same time, the effect of preventing crushing of the formed aggregates is further enhanced, which is preferable.

Further, by immersing the fibrous body 8 disposed in the lower part of the filtration tank 7 in the coagulated water, the aggregates in the coagulated water are removed, and the treated water is obtained. As the fibrous body 8, those having nap of ultra-fine fibers may be used as they are, or a plurality of the fibrous bodies may be used as a fibrous body bundle which is bundled by a binding member. Further, as the material of the fibrous body 8,
Specifically, polypropylene, nylon, polysulfone, fluororesin and the like are mentioned.

The filtration speed at the time of performing the fiber filtration is not particularly limited as long as the aggregate can be sufficiently removed, but is preferably 20 to 40 m / h.

In the fiber filtration step, the filtration efficiency decreases with an increase in the amount of aggregates attached to the fibrous body 8,
The turbidity and chromaticity of the resulting treated water tend to increase,
In such a case, it is preferable to backwash the fiber filtration means. As an index when performing backwashing of the fiber filtration means,
In addition to the turbidity and chromaticity of the treated water, the differential pressure of the filtration means and the like may be mentioned.
When the pressure is equal to or higher than the above, or when the differential pressure of the filtration means is equal to or higher than a certain value (usually, 20 to 50 kPa), it is preferable to perform the backwash.

The backwashing of the filtering means can be suitably performed using, for example, the backwashing means shown in FIG. That is, the water to be treated in the filtration water tank 11 is used as backwash water, and the backwash water is sent from the backwash line 16 provided with the backwash water supply means 14 and the backwash water discharge valve 15 into the filtration tank 7, and the fiber The body 8 is backwashed. The backwash water after the backwash is discharged out of the filtration tank 7 from a treated water discharge line 18 provided with a treated water discharge valve 17.

When the treated water thus obtained is sent to the filtration treatment tank 11, its turbidity and / or chromaticity are measured by the measuring means 12. Then, based on the obtained measurement values, the line mixers 2a, 2a, 2
The addition amounts of the flocculant and the pH adjuster in b are adjusted online. As the measuring means 12, one of a turbidity meter and a chromaticity meter may be used, or both may be used in combination.

As described above, the line mixers 2a and 2b are used as a means for mixing the raw water, the flocculant and the pH adjuster, and the mixed water is supplied to the flocculation section 10 provided above the filtration tank 7 of the fiber filtration means 3 in a predetermined manner. By holding for a period of time, crushing of aggregates can be sufficiently prevented. Further, by adding a flocculant and a pH adjuster to the raw water using the line mixers 2a and 2b, the followability is improved and the stable pH is improved.
Certain components can be aggregated under conditions. Therefore, by the water treatment apparatus and method of the present invention, it is possible to efficiently and reliably obtain treated water in which turbidity and chromaticity are sufficiently reduced.

[0028]

EXAMPLES Hereinafter, the present invention will be described more specifically based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1 The water treatment apparatus shown in FIG. 1 was used to treat river water having a turbidity of 80 degrees. That is, ferric chloride (FeCl ₃ ) was added to river water as raw water in the line mixer 2a, and then sodium hydroxide was added in the line mixer 2b to obtain mixed water having a pH of 5.8. The amount of ferric chloride added was controlled so that the (Fe / turbidity) ratio was 0.1 based on the turbidity of the treated water obtained after fiber filtration described below (the same applies hereinafter). ).

Next, the mixed water is introduced in the circumferential direction from the upper part of the filtration tank 7 of the filtering means 3 and held for 120 seconds in the aggregating section 10 to aggregate suspended and suspended substances in the mixed water. Filtration was performed to remove aggregates to obtain treated water. The fibrous body 8
Used was a bundle of a plurality of polypropylene fibers having a length of 1100 cm. The filtration speed at the time of fiber filtration was 750 m / h (the same applies hereinafter).

FIG. 3 shows the correlation between the treatment time and the pH when the pH of the mixed water sequentially sent to the aggregating section was measured in the above process. Table 1 shows the turbidity of the obtained treated water.

As shown in FIG. 3, in Example 1, flocculation of suspended matters and suspensions in the mixed water could be carried out under sufficiently stable pH conditions. Further, as shown in Table 1, the obtained treated water had sufficiently reduced turbidity.

COMPARATIVE EXAMPLE 1 Using the water treatment apparatus shown in FIG. 2, water treatment of river water having a turbidity of 80 degrees was performed. That is, to the river water as raw water, ferric chloride was added in the mixing tank 19, and sodium hydroxide was added in the coagulation tank 20, to obtain coagulated water.

Next, the coagulated water was sent to a filtration tank using a pump, and the coagulated matter was removed by fiber filtration to obtain treated water.

FIG. 4 shows the correlation between the treatment time and the pH when the pH of the coagulated water sequentially sent to the filtration tank was measured in the above process. Table 1 shows the turbidity of the obtained treated water.

In Comparative Example 1, as shown in FIG.
The fluctuation of pH in the flocculated water was large. Further, as shown in Table 1, the turbidity of the obtained treated water could not be sufficiently reduced.

[0037]

[Table 1]

Example 2 Water treatment was carried out in the same manner as in Example 1 except that river water having a turbidity of 30 ° was used as raw water. Agglomeration of the suspension could be performed. Table 2 shows the turbidity of the obtained treated water.

Comparative Example 2 Water treatment was performed in the same manner as in Comparative Example 1 except that river water having a turbidity of 30 ° was used as raw water. A change in pH during the operation was observed. Table 2 shows the turbidity of the obtained treated water.

[0040]

[Table 2]

Example 3 Water treatment was carried out in the same manner as in Example 1 except that river water having a turbidity of 10 ° was used as raw water. Agglomeration of the suspension could be performed. Table 3 shows the turbidity of the obtained treated water.

Comparative Example 3 Water treatment was performed in the same manner as in Comparative Example 1 except that river water having a turbidity of 10 ° was used as raw water. A change in pH during the operation was observed. Table 3 shows the turbidity of the obtained treated water.

[0043]

[Table 3]

Example 4 Water treatment was carried out in the same manner as in Example 1 except that river water having a turbidity of 1 degree was used as raw water. Agglomeration of the suspension could be performed. Table 4 shows the turbidity of the obtained treated water.

Comparative Example 4 Water treatment was performed in the same manner as in Comparative Example 1 except that river water having a turbidity of 1 degree was used as raw water. A change in pH during the operation was observed. Table 4 shows the turbidity of the obtained treated water.

[0046]

[Table 4]

[0047]

As described above, according to the present invention, in a water treatment for aggregating and removing predetermined components in raw water, aggregates are formed under stable pH conditions, and the generated aggregates are crushed. , Turbidity and chromaticity can be efficiently and reliably obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a preferred embodiment of a water treatment apparatus of the present invention.

FIG. 2 is a schematic configuration diagram illustrating an example of a conventional water treatment apparatus.

FIG. 3 is a graph showing the correlation between the treatment time and the pH obtained in Example 1.

FIG. 4 is a graph showing the correlation between the treatment time and pH obtained in Comparative Example 1.

[Explanation of symbols]

1, 1 '... water treatment device, 2a, 2b ... line mixer,
3 ... Fiber filtration means, 4 ... Flow path, 5a, 5b ... Container, 6
a, 6b: valve, 7: filtration tank, 8: fibrous body, 8 '...
Filtration body, 9 introduction section, 10 aggregation section, 11 filtration treatment tank, 12 measurement means, 13 control means, 14 backwash water supply means, 15 backwash water discharge valve, 16 backwash line , 17
... treated water discharge valve, 18 ... treated water discharge line, 19 ... mixing tank, 20 ... coagulation tank.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01F 3/12 B01F 5/00 B 5/00 C02F 1/56 Z C02F 1/56 B01D 29/08 520C

Claims (5)

[Claims] 1. A line mixer for injecting a coagulant and a pH adjuster into raw water to make mixed water, an introduction part for introducing the mixed water, and a coagulating part for holding the mixed water for a predetermined time to form coagulated water A water treatment apparatus, comprising: a cylindrical filtration tank provided at an upper part thereof; and a fiber filtration means including a fibrous body disposed at a lower part of the filtration tank. 2. The water treatment according to claim 1, wherein the introduction portion is provided on an outer peripheral surface of the filtration tank, and the mixed water is introduced in a circumferential direction of the filtration tank. apparatus. 3. A measuring means for measuring the turbidity or chromaticity of the treated water discharged from the fiber filtration means; a coagulant injected into the line mixer based on the turbidity or the chromaticity; 2. The control device according to claim 1, further comprising control means for controlling an addition amount of the pH adjuster.
Or the water treatment apparatus according to 2. 4. A raw material passing through a line mixer and a coagulant and p
An admixing step of adding an H adjuster to obtain admixed water; a fiber filtration comprising: a cylindrical filtration tank provided with an introduction section and an aggregation section at an upper portion; and a fibrous body arranged at a lower portion of the filtration tank. In the means, by introducing mixed water from the upper part of the filtration tank, a coagulation step of obtaining the coagulated water by holding the mixed water for a predetermined time in the coagulation section, by immersing the fibrous body in the coagulated water A filtration step of filtering the coagulated water to obtain treated water. 5. The method according to claim 1, further comprising a control step of controlling an addition amount of a flocculant and / or a pH adjuster in the mixing step based on turbidity and / or chromaticity of the treated water. Item 5. The water treatment method according to Item 4.