JP2000093944A - Method for treating surfactant-containing water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method for treating surfactant-containing water wherein high quality treated water can be obtained while the surfactant can efficiently be eliminated by using a small amount of chemicals. SOLUTION: Surfactant-containing water 5 is separated by bubbling in a bubble separation tank 1, into a bubble liquid 8 in which the surfactant is concentrated and separated water 9 without containing the surfactant. The surfactant is made insoluble by making the bubble liquid react by adding a coagulation agent 13 in a coagulation treating tank 2, the coagulation treated liquid 15 together with separated water 12 is treated by aggregation in an aggregation treating tank 3 to be separated into a solid and a liquid in a solid-liquid separating tank 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for treating water containing a surfactant.

[0002]

2. Description of the Related Art Surfactants are used in many fields, and wastewater containing various surfactants is discharged. If such surfactant-containing water is discharged as it is, it pollutes the environment. Therefore, it is required to treat and discharge the water. There are various types of surfactants such as anionic, cationic, amphoteric, and nonionic, but all of them have a hydrophilic group and a lipophilic group, so it is difficult to separate them from water, Inhibits processing properties such as processing and coagulation.
In particular, nonionic surfactants are difficult to separate from water.

Conventional methods for treating surfactant-containing water include activated carbon adsorption, biological treatment, foam separation, and treatment with a coagulant. Activated carbon adsorption has a problem in that the cost of activated carbon is high, and in biological treatment, the treatment speed is slow and the apparatus becomes large. Foam separation is a method of concentrating a surfactant in a foam layer by attaching a surfactant to bubbles and raising the same. However, a large amount of foam liquid is generated, and the treatment thereof is difficult.

[0004] The treatment method using a coagulant is a method in which a coagulant that reacts with a surfactant is added to water containing a surfactant to perform a coagulation treatment. However, in this method, other components present in the water also react with the coagulant to consume the coagulant,
There is a problem that a large amount of drug is required.

[0005] An object of the present invention is to provide a method for treating surfactant-containing water, which can efficiently remove a surfactant using a small amount of chemicals and can obtain treated water of high quality.

The present invention is the following method for treating surfactant-containing water. (1) A foam separation step in which the surfactant-containing water is foam-separated and separated into a foam liquid and separated water, a coagulation step in which a coagulant is added to the obtained foam liquid to coagulate the surfactant, and a foam separation. And a flocculating step of flocculating the separated water. (2) The method according to the above (1), wherein in the aggregation step, the separation water in the foam separation step and the condensate in the condensation step are subjected to an aggregation treatment.

In the present invention, the raw water to be treated (water to be treated) is surfactant-containing water. Surfactants are substances that have a hydrophilic group and a lipophilic group, and are anionic, cationic, amphoteric, nonionic, etc., each of which contains various substances, but all surfactants are subject to treatment Becomes Among them, it is particularly effective for treating a nonionic surfactant. Examples of such surfactant-containing water include sewage, surfactant production wastewater, semiconductor production wastewater (including polyimine development wastewater and stripping wastewater), and various kinds of washing wastewater. Surfactant concentration in raw water is 1-1000mg / l,
Particularly, it is preferably 100 mg / l or less. When the surfactant concentration is high, most of the water to be treated becomes a foam liquid, and when the surfactant concentration is low, foam separation cannot be performed.

In the treatment method of the present invention, the above-mentioned surfactant-containing water is first subjected to foam separation in a foam separation step to separate it into a foam liquid and separated water. Foam separation is performed by introducing bubbles into surfactant-containing water and bringing them into gas-liquid contact, making use of the property that surfactants tend to collect at the interface. This is an operation for separating the foam liquid in which the activator is concentrated, and the conventional operation for foam separation can be used as it is.

[0009] Such a foam separation method is preferably a method in which surfactant-containing water is introduced into the separation tank, bubbles are finely introduced into the water to be treated by using a bubble introduction means, and the bubbles are floated. As a bubble introduction means, a perforated plate type is generally used, but a means for making air bubbles finer with a rotating blade may be used, or a pressure flotation method in which air is dissolved under pressure and reduced pressure is generated to generate fine bubbles. You may.

[0010] When bubbles are introduced into the water to be treated by the foam separation method, the surfactant in the water gathers around the bubbles and rises, and the surfactant is concentrated in the foam layer. Therefore, by separating the foam liquid formed at the top of the foam separation tank,
A foam liquid in which the surfactant is concentrated and separated water from which the surfactant has been removed are obtained. Foam liquid volume is 1/100 of raw water volume
Preferably it is 1/20.

In the present invention, in the coagulation step, the coagulant is added to the above-mentioned foam liquid in which the surfactant is concentrated to insolubilize the surfactant. The coagulant is a chemical which reacts with the surfactant to form an insoluble precipitate, and any agent which has been conventionally used for coagulation of a surfactant can be used as it is.

As such a coagulant, for example, an acid colloid solution of a melamine-formaldehyde condensate (Japanese Patent Publication No.
No. 15243), a vinylphenol polymer (Japanese Unexamined Patent Publication No.
No. 146191). Commercially available products include Clearide L101 and L401 (Kurita Kogyo Co., Ltd.)
And Sefner N (trademark, manufactured by Matsuken Corporation).

The acid colloid of melamine-formaldehyde condensate is obtained by reacting formaldehyde with 1.8 to 2.5 moles per mole of melamine,
Formaldehyde is 1.8 to 2. per mole of melamine.
This is an acid colloid solution of methylol melamine having 5 moles bonded thereto, which is added to a foam liquid and reacted with the surfactant to insolubilize the surfactant. The above coagulants insolubilize any of anionic, amphoteric and nonionic surfactants, and are particularly suitable for treating nonionic surfactants.

The vinylphenol polymers include: a): a homopolymer of vinylphenol, b): a homopolymer of modified vinylphenol, and c): a copolymer of vinylphenol and / or modified vinylphenol with a hydrophobic vinyl monomer. The surfactant is insolubilized by adding and reacting an aqueous alkali solution of a polymer selected from polymers. The above coagulants insolubilize any of the cationic, amphoteric and nonionic surfactants, and are particularly suitable for treating nonionic surfactants.

In the case of other coagulants, the surfactant is similarly insolubilized. These coagulants include BOD such as polysaccharides, proteins and organic acids which are components other than surfactants.
Component, an organic component such as a COD component, and an inorganic component such as a metal ion such as calcium, magnesium, iron, nickel, aluminum, zinc, and chromium (III).

In the present invention, by foam separation in advance,
Since the surfactant is concentrated in the foam liquid, if a coagulant is reacted with the surfactant, the coagulant can be effectively reacted without wasteful use. That is, foam separation selectively concentrates a surfactant and leaves other components in separated water, so that the amount of coagulant consumed by other components can be reduced.

The amount of the coagulant varies depending on the type and concentration of the coagulant and the surfactant, and other conditions. In general, the amount is 1 to 20 times by weight, preferably 2 to 10 times by weight of the surfactant. It is. Since insoluble precipitates are formed by the reaction between the coagulant and the surfactant, the precipitates can be removed by solid-liquid separation, and the separated liquid can be discharged as it is.
In the following coagulation step, it is preferable to perform coagulation treatment in combination with the separated water in the foam separation step.

In the coagulation step, COD components and other organic substances remaining after coagulation treatment of the separated water subjected to foam separation, and S
In this step, S, metal ions, and other inorganic substances are aggregated to form flocs. Here, it is preferable that the coagulation treatment liquid of the foam liquid is subjected to coagulation treatment as it is together with the separation water in the foam separation step.

In the coagulation treatment, an inorganic coagulant such as a sulfuric acid band, aluminum chloride, PAC, and iron salt, an organic polymer coagulant such as poly (meth) acrylamide and a partial hydrolyzate thereof, which are used in general coagulation treatment, and A pH adjuster such as hydrochloric acid and sodium hydroxide can be used. The operation of the coagulation treatment is the same as the coagulation treatment in general water treatment. The coagulation treatment liquid undergoes solid-liquid separation in the solid-liquid separation step,
The separated liquid is discharged, and the sludge is subjected to sludge treatment such as dehydration and incineration.

Since the surfactant which inhibits aggregation is removed from the separated water in the foam separation step, the aggregation is carried out efficiently, and high-quality treated water can be obtained. When the coagulation treatment is performed by adding the coagulation treatment liquid of the foam liquid to the separation water in the foam separation step, the coagulation treatment is performed in a state where the surfactant in the foam liquid is insolubilized by coagulation, so that the coagulation by the surfactant is inhibited. Does not happen.

When the coagulation treatment is performed by adding the coagulation liquid of the foam liquid to the separation water in the foam separation step, the solid-liquid separation step of the coagulation liquid is further omitted, which simplifies the apparatus and operation. Since the remaining coagulant is also consumed in the coagulation treatment step, the quality of the treated water is improved, and the control of the addition amount of the coagulant in the coagulation step is rough and easy, so that the operation is simplified.

The coagulation treatment liquid and the coagulation treatment liquid are separated into a treatment liquid and a sludge by solid-liquid separation. The solid-liquid separation means for this purpose includes general separation methods such as sedimentation separation, membrane separation, pressure flotation separation, and filtration. Solid-liquid separation means can be employed. Further, known treatment methods such as activated sludge treatment and thermal decomposition treatment may be combined.

[0023]

According to the present invention, the surfactant-containing water is subjected to foam separation, the foam liquid is reacted with a coagulant to perform coagulation treatment, and the separated water of foam separation is subjected to coagulation treatment. Enables the surfactant to be concentrated and reacted with the coagulant, the use of the coagulant is reduced, and the surfactant can be efficiently removed by the coagulation treatment. The flocculation treatment can be performed efficiently in a state where the agent is not inhibited, and high-quality treated water can be obtained.

Further, by coagulating the condensed liquid of the foam liquid and the separated water of the foam separation, the apparatus and the operation can be simplified and the surfactant can be efficiently removed.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart illustrating a processing method according to the embodiment. In FIG. 1, 1 is a foam separation tank, 2 is a coagulation treatment tank, 3 is a coagulation treatment tank, and 4 is a solid-liquid separation tank.

The treatment of the surfactant-containing water is performed in the foam separation tank 1
The raw water is introduced from the raw water channel 5 and the bubbles 7 are introduced from the bubble introducing device 6 to perform foam separation. The surfactant in the raw water gathers around the bubbles 7, gathers near the liquid surface as the bubbles 7 rise, and is separated into the foam liquid 8 and the separation water 9. The foam liquid 8 is sent from the line 11 to the coagulation tank 2 by the skimmer 10, and the separated water 9 is sent to the coagulation tank 3 from the line 12.

In the coagulation treatment tank 2, a coagulant is injected from the chemical injection path 13, and a coagulation reaction is performed by stirring with a stirrer 14, and the surfactant in the foam liquid 8 is reacted with the coagulant to precipitate as an insoluble compound. Let it. The coagulation liquid 15 is sent from the line 16 to the coagulation tank 3.

In the coagulation tank 3, coagulation is performed by combining the separated water 9 sent from the line 12 and the coagulation liquid 15 sent from the line 16. In this case, an aggregating agent is injected from the chemical injection path 17 and a pH adjusting agent is injected from the chemical injection path 18, and the aggregation is performed by stirring with the agitator 19. Although the aggregating process is configured to perform rapid stirring and slow stirring, it is illustrated in a simplified manner.

By the coagulation treatment, SS, BO in the separated water 9
Components such as the D component, the COD component, and the metal ions, and the insolubilized surfactant in the coagulation treatment liquid 15 aggregate and floc. This coagulation treatment liquid 20 is sent from the line 21 to the solid-liquid separation tank 4 where solid-liquid separation is performed, and the separated liquid is discharged from the treatment water passage 22 as it is or after being further purified by biological treatment or the like as treated water. The sludge is sent from the sludge passage 23 to the sludge treatment device.

In the above-mentioned treatment, the surfactant is concentrated into a foam liquid and subjected to the coagulation treatment, so that the amount of the coagulant used can be reduced and the surfactant can be efficiently insolubilized. In the separated water from which the surfactant has been removed, since the surfactant that inhibits aggregation is removed, the aggregation treatment can be performed efficiently.

In the above embodiment, the coagulation treatment liquid 15 is guided to the coagulation treatment tank 3 and is treated together with the separation water 9.
The treatment can be performed by a single solid-liquid separation tank 4, and the apparatus and operation can be simplified, and the quality of treated water can be improved. Further, after the separated water 9 is further treated (not shown here) with activated sludge or the like, the coagulation treatment may be performed together with the coagulation treatment liquid 15. In this case, since the surfactant has been removed in advance, the treated water BO can be used without causing problems such as inhibition of biological reactions and foaming in the activated sludge treatment.
The D concentration can be further reduced.

As another embodiment, the coagulation treatment liquid 15 is introduced from a line 24 to another solid-liquid separation device 25 to perform solid-liquid separation.
The separated liquid may be discharged from the treatment water channel 26. As the solid-liquid separation device, a sedimentation separation tank, a filtration tank and a membrane separation device can be suitably used.

[0033]

Example 1 Washing water in a semiconductor manufacturing process of TOC (1530 mg / l) as surfactant-containing water was treated according to the flow indicated by the solid line in FIG. First, 1 liter of air is added to 1 liter of raw water.
For 15 minutes to separate the foam,
liter and separated water 0.9 liter. Polyvinylphenol as coagulant (average molecular weight 300
0) 12 mg was added to perform a coagulation treatment, and the coagulation treatment liquid was mixed with separated water to form an inorganic coagulant of 400 m FeCl _3.
g and a copolymer of acrylic acid and acrylamide as the anionic organic polymer flocculant (polymerization molar ratio of acrylic acid and acrylamide 20:80, average molecular weight 1000)
) Was added to perform a coagulation treatment, and a sedimentation separation was performed as solid-liquid separation.
l.

Example 2 In Example 1, the processing was performed according to the processing flow indicated by the broken line in FIG. That is, when the coagulation treatment liquid 15 was introduced into the membrane separation device as the solid-liquid separation device 25 from the line 24 to perform solid-liquid separation, the TOC of the treatment water taken out from the treatment water passage 26 was not detected. On the other hand, the separated water 9 is aggregated in the aggregation tank 3 and then treated in the solid-liquid separation tank 4.
C was 690 mg / l.

Comparative Example 1 In Example 1, 360 mg of a coagulant was added directly to raw water without foam separation to cause a reaction, and then coagulation treatment and solid-liquid separation were performed under the same conditions.
C was 940 mg / l.

Comparative Example 2 In Comparative Example 1, when the amount of the coagulant added was changed to 660 mg, the treated water TOC was 680 mg / l.

The results are shown in Table 1.

[Table 1]

From the above results, the example can be treated efficiently with a smaller amount of coagulant than the comparative example.
It can be seen that the OC is low, and high-quality treated water is obtained. In particular, in Example 1, the treated water TOC is low.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a processing method according to an embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 foam separation tank 2 coagulation treatment tank 3 coagulation treatment tank 4 solid-liquid separation tank 5 raw water passage 6 bubble introduction device 7 bubble 8 foam liquid 9 separation water 10 skimmer 11, 12, 16, 21 line 13, 17, 18 14, 19 Stirrer 15 Coagulation treatment liquid 20 Coagulation treatment liquid 22 Treatment water passage 23 Sludge passage

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[Procedure amendment]

[Submission date] September 29, 1998 (1998.9.2)
9)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction contents]

Comparative Example 1 In Example 1, 36 mg of a coagulant was directly added to raw water without foam separation to cause a reaction, and then coagulation treatment and solid-liquid separation were performed under the same conditions.
Was 940 mg / l.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction contents]

Comparative Example 2 In Comparative Example 1, when the amount of the coagulant added was changed to 66 mg, the treated water TOC was 680 mg / l.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0037

[Correction method] Change

[Correction contents]

The results are shown in Table 1.

[Table 1]

Claims (2)

[Claims] 1. A foam separation step of separating a surfactant-containing water by foam to separate it into a foam liquid and separated water; a coagulation step of adding a coagulant to the obtained foam liquid to coagulate the surfactant; A coagulation step of coagulating water separated by foam separation. 2. The coagulation step in which coagulation is performed by combining the separated water in the foam separation step and the condensate in the coagulation step.
The described method.