JP4866221B2 - Filtration treatment apparatus and filtration treatment method - Google Patents

Description

  The present invention relates to a filtration apparatus and a filtration method.

  Conventionally, a filtration treatment apparatus using sand filtration or membrane filtration has been used for filtration of raw water to be filtered. Recently, a filtration apparatus using fiber filtration may be used. Fiber filter media used for fiber filtration have the characteristics of large specific surface area, large porosity and low filtration resistance, and are attracting attention as filter media that can perform high-speed and high-performance filtration. Used for rough filtration and tertiary treatment of sewage.

  When raw water containing suspended solids (SS) is filtered by a filtration apparatus using the fiber filter medium, SS in the raw water is captured by the fiber filter medium. However, when the filtration process is further continued, microorganisms propagate by the organic matter contained in the raw water, and deposits (slime) derived from the microorganisms adhere to the fiber filter medium. As a result, the inside of the filter is clogged, and the filtration differential pressure increases. The slime is difficult to remove by ordinary backwashing or the like. Therefore, in order to suppress the growth of microorganisms, an inorganic slime control agent such as sodium hypochlorite and sodium hypobromite is added to the raw water to sterilize the microorganisms (for example, Patent Document 1).

Since the inorganic slime control agent has strong oxidizing power, it exhibits a bactericidal effect by oxidative degradation of proteins and cell membranes. However, the following problems occur.
(1) Since the SS captured by the fiber filter medium is also decomposed by the strong oxidizing power of the inorganic slime control agent, the decomposed SS falls off the fiber filter medium and is mixed into the treated water. As a result, the quality of treated water deteriorates.
(2) Due to the strong oxidizing power of the inorganic slime control agent, the fiber filter medium is also decomposed, and the strength, stretch rate, etc. of the fiber are lowered.
(3) While the inorganic slime control agent has a rapid effect, it is consumed in a short time by oxidative decomposition, so the bactericidal effect is not sustained. Therefore, when the operation of the filtration apparatus is stopped, since raw water containing an inorganic slime control agent is not supplied, microorganisms are propagated and slime is likely to be generated.

In particular, when a long fiber bundle is used as the fiber filter medium, the problem (1) appears remarkably for the following reason.
In the long fiber bundle, since the lower end of the long fiber is fixed to the support, the density of the long fiber is high on the lower end side of the long fiber bundle, and the density of the long fiber is low on the upper end side. And the support body of this long fiber bundle is being fixed to the partition plate near the bottom part of a filter. Therefore, SS tends to adhere to the lower end side of the long fiber bundle close to the treated water outlet at the bottom of the filter. As a result, the SS that has been decomposed by the inorganic slime control agent and dropped from the vicinity of the lower end of the long fiber bundle is mixed into the treated water without being recaptured by the long fiber bundle.
Japanese Patent Laid-Open No. 7-241549

  The present invention provides a filtration treatment apparatus and a filtration treatment method in which the propagation of microorganisms in a filter is suppressed, the deterioration of the quality of treated water is suppressed, and the deterioration of fiber filter media is suppressed.

The filtration device of the present invention comprises a filter filled with a fiber filter medium for filtering raw water, and a chemical addition means for adding an organic slime control agent to the raw water.
As the fibrous filter material, fiber維束are preferred.
In the filtration apparatus of the present invention, before the lower end of Ki繊維束is fixed near the bottom of the filter, it is preferable to have a treated water outlet at the bottom of the filter.
Further, in the filtration apparatus of the present invention, in a state where the front Ki繊維束is folded in two halves, which bent portion is secured near the bottom of the filter, the treated water outlet at the bottom of the filter It is preferable to have.
As the organic slime control agent, an isothiazolone compound is preferable.
The filtration method of the present invention is characterized in that an organic slime control agent is added to raw water, and the raw water is filtered with a filter filled with a fiber filter medium.
As the fibrous filter material, fiber維束are preferred.
In the filtration treatment method of the present invention, the lower end of the front Ki繊維束fixed near the bottom of the filter, to supply raw water from the top of the filter, it is preferable to drain the treated water from the bottom.
In the filtration treatment method of the present invention, before the Ki繊維束in a folded state into two halves to secure the bent portion near the bottom of the filter, raw water is supplied from the top of the filter The treated water is preferably drained from the bottom.
As the organic slime control agent, an isothiazolone compound is preferable.

  According to the filtration device and the filtration method of the present invention, the growth of microorganisms in the filter can be suppressed, the deterioration of the quality of the treated water can be suppressed, and the deterioration of the fiber filter medium can be suppressed.

(Filtration processing equipment)
FIG. 1 is a schematic configuration diagram showing an example of the filtration apparatus of the present invention. The filtration treatment apparatus 10 includes a raw water tank 12, a filter 14, a treated water tank 16, a chemical liquid tank 18 (a part of chemical solution adding means), a backwash blower 20, and raw water in the raw water tank 12 of the filter 14. The raw water supply pipe 22 supplied to the upper part, the treated water supply pipe 24 for supplying the treated water drained from the treated water outlet (not shown) at the bottom of the filter 14 to the treated water tank 16, and the treated water in the treated water tank 16 A backwash water supply pipe 26 that returns to the bottom of the filter 14, a backwash water drain pipe 27 that drains backwash water from the top of the filter 14, and a chemical solution in the chemical tank 18 into the raw water in the middle of the raw water supply pipe 22. A chemical solution supply pipe 28 to be supplied (a part of the chemical solution addition means), an air supply pipe 30 that supplies air from the backwash blower 20 to the bottom of the filter 14, and raw water in the raw water tank 12 is sent to the raw water supply pipe 22. The raw water pump 32 and the backwash water supply pipe 26 for the treated water in the treated water tank 16. A backwash water pump 36 for supplying water, a chemical pump 38 (a part of the chemical addition means) for supplying the chemical liquid in the chemical tank 18 to the chemical supply pipe 28, and an air valve 40 provided in the middle of the air supply pipe 30 The raw water valve 42 provided in the middle of the raw water supply pipe 22 downstream from the confluence of the chemical liquid supply pipe 28, the treated water valve 44 provided in the middle of the treated water supply pipe 24, and the backwash water supply pipe 26 is provided with a backwash water valve 46 provided in the middle of No. 26, a drain valve 47 provided in the middle of the backwash water drain pipe 27, and a flow meter 50 provided in the middle of the raw water supply pipe 22.

The filter 14 includes a cylindrical container 52, a partition plate 54 provided in the vicinity of the bottom, and a long fiber bundle 56 (fiber filter material) filled in a state of being fixed to the partition plate 54.
The long fiber bundle 56 includes a plurality of long fibers 62 and a support body 64 that fixes a lower end of the long fibers 62. The long fiber 62 is fixed by winding the wire around the support 64 while passing the wire (not shown) through the bent portion in a state of being bent in half. The support 64 is formed with a treated water intake (not shown) and a treated water feed channel (not shown) for feeding treated water on the upper side of the partition plate 54 to the bottom side of the partition plate 54. Has been.

  Instead of the long fiber bundle 56, other fiber filter media may be used. Examples of the other fiber filter medium include a filter medium in which short fibers are woven into a cloth, a filter medium in which the fibers are processed into cotton, and a filter cloth made of a woven or non-woven fiber.

(Filtration processing method)
A filtration method using the filtration device 10 shown in FIG. 1 will be described.
When the raw water is filtered, the raw water valve 42 and the treated water valve 44 are opened, and the air valve 40, the backwash water valve 46, and the drain valve 47 are closed.

  The raw water in the raw water tank 12 sent to the raw water supply pipe 22 by the raw water pump 32 is supplied to the upper portion of the filter 14 through the raw water supply pipe 22. At this time, the chemical solution in the chemical solution tank 18 fed to the chemical solution supply pipe 28 by the chemical solution pump 38 is supplied to the raw water in the raw water supply pipe 22 through the chemical solution supply pipe 28 at a predetermined injection amount.

The raw water containing the chemical solution supplied from the upper part of the filter 14 is filtered when passing through the filter 14, and drained as treated water from the treated water outlet at the bottom of the filter 14. At this time, SS contained in the raw water is captured by the long fiber bundle 56 in the filter 14.
The treated water drained from the bottom of the filter 14 is supplied to the treated water tank 16 through the treated water supply pipe 24.

When the long fiber bundle 56 in the filter 14 is backwashed, the raw water valve 42 and the treated water valve 44 are closed, and the air valve 40, the backwash water valve 46 and the drain valve 47 are opened.
The treated water in the treated water tank 16 sent to the backwash water supply pipe 26 by the backwash water pump 36 is returned to the bottom of the filter 14 as backwash water through the backwash water supply pipe 26. At the same time, the air from the backwash blower 20 is supplied to the bottom of the filter 14 via the air supply pipe 30.

The backwash water supplied from the bottom of the filter 14 passes through the filter 14 and is drained from a backwash water outlet (not shown) at the top of the filter 14. At this time, SS or the like captured by the long fiber bundle 56 is removed by backwashing water. Further, by supplying air from the bottom of the filter 14 simultaneously with the backwash water, the backwash water and the long fiber bundle 56 passing through the filter 14 are efficiently stirred and captured by the long fiber bundle 56. Etc. are efficiently removed.
The backwash water containing SS and air drained from the upper part of the filter 14 is discharged out of the apparatus through the backwash water drain pipe 27.

  The chemical is an organic slime control agent. An organic slime control agent is an organic compound that sterilizes microorganisms by actions such as protein synthesis inhibition, protein denaturation, DNA synthesis inhibition, cell membrane destruction (excluding oxidative degradation), TCA cycle enzyme group inhibition, respiratory enzyme inhibition and the like.

  Examples of organic slime control agents include organic nitrogen halogen slime control agents and organic amine slime control agents. Examples of the organic nitrogen halogen-based slime control agent include isothiazolone compounds (see JP-A-4-182474). The isothiazolone compound sterilizes microorganisms by the action of protein synthesis inhibition and TCA cycle enzyme group inhibition.

  The amount of the chemical solution injected into the raw water is preferably such that the concentration of the organic slime control agent in the raw water is 0.1 to 1000 mg / L. If the concentration of the organic slime control agent is within this range, a sufficient bactericidal effect can be obtained.

  The addition of the organic slime control agent to the raw water may be performed continuously or intermittently as long as the concentration of the organic slime control agent in the raw water is within the above range.

  You may add a slime control agent to backwash water as needed. Examples of slime control agents include inorganic slime control agents and organic slime control agents.

In the filtration treatment apparatus of the present invention described above, since it comprises a chemical addition means for adding an organic slime control agent to raw water, the growth of microorganisms in the filter can be suppressed, and at the same time the quality of the treated water Deterioration of the fiber filter medium is suppressed.
Moreover, in the filtration method of the present invention, since the organic slime control agent is added to the raw water before the raw water is filtered, the growth of microorganisms in the filter is suppressed, and at the same time Deterioration of water quality is suppressed, and deterioration of the fiber filter medium is suppressed.

That is, the conventional inorganic slime control agent has a sterilization mechanism based on oxidative degradation of proteins and cell membranes, whereas the organic slime control agent in the present invention does not have a sterilization mechanism based on oxidative degradation. Therefore, microorganisms can be sterilized without decomposing SS captured by the fiber filter medium. Therefore, deterioration of the quality of treated water can be suppressed.
Moreover, since the organic slime control agent in this invention does not decompose | disassemble a fiber filter medium, the fall of the intensity | strength of a fiber, an expansion-contraction rate, etc. is suppressed.

Then, by adding an organic slime control agent to the raw water, the growth of microorganisms in the filter is suppressed, and the generation of slime is suppressed. In addition, organic slime control agents are not consumed in a short time due to oxidative degradation, and the bactericidal effect lasts for a long time, so that the growth of microorganisms can be suppressed even when the filtration device is stopped. , Slime generation is suppressed.
In the filtration apparatus and the filtration method of the present invention, the SS trapped in the fiber filter medium is not decomposed and does not fall off from the fiber filter medium. Therefore, when an inorganic slime control agent is used, the SS dropped from the fiber filter medium. Is particularly effective when long fiber bundles that are likely to be mixed into the treated water are used as fiber filter media.

(SS concentration)
The SS concentration in the raw water and treated water was measured by a suspended substance measuring method of JIS K0102 “Factory Wastewater Test Method” using glass fiber filter paper having a pore diameter of 1 μm.

(Tensile strength)
The tensile strength of the fiber was measured by JIS L1069 “Tensile test method of natural fiber” using TCM-1KNB manufactured by Minebea.

[Example 1]
The raw water was filtered according to the filtration method described above using the filtration device 10 shown in FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG.
Polyester fibers were used as the long fiber bundle 56.
As raw water, wastewater from a paper mill was used. The filtration rate LV in the two filters 14 was 50 m / h, respectively.

One chemical solution tank 18 was filled with 10% by mass of an isothiazolone compound aqueous solution, and the other chemical solution tank 18 was filled with 12% by mass of a sodium hypochlorite aqueous solution.
While supplying the raw water of the raw water tank 12 to one filter 14, the aqueous solution of isothiazolone compound was continuously poured into the raw water so that the concentration of the isothiazolone compound in the raw water was 1.0 mg / L.
Moreover, while supplying the raw water in the raw water tank 12 to the other filter 14, the sodium hypochlorite aqueous solution is continuously supplied to the raw water so that the concentration of sodium hypochlorite in the raw water becomes 1.0 mg / L. Injected into.

Backwashing was performed every 24 hours for 6 minutes.
24 hours after the start of the filtration treatment, the SS concentration in the raw water was measured. Moreover, the treated water drained from each filter 14 was sampled, and the SS concentration in the treated water was measured. The measurement results are shown in Table 1.

[Example 2]
After thoroughly washing the two filters 14, the raw water was filtered in the same manner as in Example 1 except that the concentrations of the isothiazolone compound and sodium hypochlorite in the raw water were changed to 2.0 mg / L. It was.
The SS concentration in the raw water and the SS concentration in the treated water were measured 24 hours after the start of the filtration treatment. The measurement results are shown in Table 1.

[Example 3]
After thoroughly washing the two filters 14, the raw water was filtered in the same manner as in Example 1 except that the concentrations of the isothiazolone compound and sodium hypochlorite in the raw water were changed to 3.0 mg / L. It was.
The SS concentration in the raw water and the SS concentration in the treated water were measured 24 hours after the start of the filtration treatment. The measurement results are shown in Table 1.

[Example 4]
After thoroughly washing the two filters 14, the raw water was filtered in the same manner as in Example 1 except that the concentrations of the isothiazolone compound and sodium hypochlorite in the raw water were changed to 4.0 mg / L. It was.
The SS concentration in the raw water and the SS concentration in the treated water were measured 24 hours after the start of the filtration treatment. The measurement results are shown in Table 1.

Generation of slime in the filter 14 was not observed both when the isothiazolone compound that is an organic slime control agent was used and when sodium hypochlorite that was an inorganic slime control agent was used.
When the isothiazolone compound was used, the quality of the treated water did not deteriorate. On the other hand, when sodium hypochlorite was used, the SS concentration in the treated water increased as the amount of sodium hypochlorite added increased, and the quality of the treated water deteriorated.

[Example 5]
Two long fiber bundles (made of polyester) were prepared and immersed in an aqueous solution of 0.4% by mass of an isothiazolone compound and an aqueous solution of 0.4% by mass of sodium hypochlorite for 30 days.
The tensile strength of unimmersed fibers, fibers immersed in an aqueous solution of isothiazolone compound, and fibers immersed in an aqueous solution of sodium hypochlorite was measured. The measurement results are shown in Table 2.

  The fiber immersed in the aqueous solution of the isothiazolone compound had the same tensile strength as that of the unused fiber, and no deterioration was observed. On the other hand, the fiber immersed in the sodium hypochlorite aqueous solution showed a decrease in tensile strength and deterioration.

  The filtration device and the filtration method of the present invention are useful for the filtration treatment of raw water containing organic substances.

It is a schematic block diagram which shows an example of the filtration processing apparatus of this invention. It is a schematic block diagram which shows the other example of the filtration processing apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Filtration processing apparatus 14 Filter 18 Chemical tank (chemical solution addition means)
28 Chemical liquid supply pipe (chemical liquid addition means)
38 Chemical liquid pump (Mechanical liquid addition means)
56 Long fiber bundle (fiber filter medium)

Claims (10)

A filter filled with fiber filter material for filtering raw water;
And a chemical addition means for adding an organic slime control agent to the raw water. The fibrous filter material is a fiber維束, filtering processing apparatus according to claim 1. Before the lower end of Ki繊維束is fixed near the bottom of the filter, having a treated water outlet at the bottom of the filter, filtering processing apparatus according to claim 2. In a state where the front Ki繊維束is folded in two halves, which bent portion is secured near the bottom of the filter, having a treated water outlet at the bottom of the filter, the filtration process according to claim 2 apparatus.   The filtration apparatus according to any one of claims 1 to 4, wherein the organic slime control agent is an isothiazolone compound.   A filtration treatment method in which an organic slime control agent is added to raw water and the raw water is filtered with a filter filled with a fiber filter medium. As the fiber filter material, using fiber維束, filtration treatment method according to claim 6. The lower end of the front Ki繊維束fixed near the bottom of the filter, to supply raw water from the top of the filter, to drain treated water from the bottom, filtration treatment method according to claim 7. In a folded state the pre Ki繊維束the bisector, the bent portion is fixed near the bottom of the filter, to supply raw water from the top of the filter, to drain treated water from the bottom, claim The filtration treatment method according to 7.   The filtration treatment method according to claim 6, wherein an isothiazolone compound is used as the organic slime control agent.

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