TW201512106A - Method for water treatment - Google Patents

Abstract

The present invention provides a method for water treatment, in which after the used water and drainage water are flocculated, a flotation separation step is conducted to efficiently proceed with floatation and separation. The object of the present invention is to provide a method for water treatment comprising a flocculation reaction step in which a flocculant is added into the treated water for flocculation, and a flotation separation step in which the flocculated treated water from the flocculation reaction step is separated into solid and liquid. The method is characterized by the flocculant which is a cationic polymer flocculant with hydrophobic functional groups. The cationic polymeric flocculant with hydrophobic functional groups can also be used together with inorganic or other polymeric flocculants.

Description

Water treatment method

The present invention relates to a water treatment method, and more particularly to a water treatment method for performing a flotation separation treatment after agglutination treatment of treated water.

In order to remove pollutants such as suspended matter or dissolved substances in various water and wastewater such as river water, industrial water, and biological treatment water, the method of flotation separation treatment is widely performed after the water for agglutination treatment is drained. For example, JP-A-H07-241597, JP-A-2002-113471, and JP-A-2007-209890 disclose a method of performing flotation separation treatment after aggregating treatment of organic drainage. The flotation separation apparatus as the solid-liquid separation means has an advantage that it is sufficient to provide a space smaller than that of the precipitation tank.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 7-241597

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2002-113471

[Patent Document 3] Japanese Laid-Open Patent Publication No. 2007-209890

An object of the present invention is to provide a water treatment method capable of efficiently performing flotation separation after a method of performing flotation separation treatment after water for agglomeration treatment.

The water treatment method according to the present invention is a water treatment method comprising an agglutination reaction step of adding a flocculating agent to the treated water to perform an agglutination reaction, and a flotation separation step of solid-liquid separation of the agglomerated treated water flowing out from the agglutination reaction step, The flocculating agent is a cationic high-molecular flocculant having a hydrophobic functional group.

The cationic high-molecular flocculant is preferably one obtained by (i) a cationic monomer having a hydrophobic functional group or (ii) a monomer having at least a hydrophobic functional group and a monomer having a cationic functional group. .

In the agglutination reaction step, an inorganic flocculant may be further added.

In the agglutination reaction step, an anionic or nonionic high-molecular flocculant may be further added.

In the present invention, after the water-drainage agglutination treatment, in the method of performing the flotation separation treatment, a cationic polymer flocculant having a hydrophobic functional group is used as the flocculating agent. This yang with hydrophobic functional groups The ionic high-molecular flocculant is a cationic substance that efficiently aggregates a suspended substance in a water-drainage which is generally negatively charged. Moreover, since the cationic high-molecular flocculant having a hydrophobic functional group has a hydrophobic functional group, the micro air for flotation separation treatment is easily adhered, and the flotation separation treatment can be efficiently performed.

In the agglutination reaction step, when an inorganic flocculant, an anionic polymer flocculant or a nonionic polymer flocculant is added, the aggregation efficiency is further improved. Further, by using a cationic high-molecular flocculant having a hydrophobic functional group, compared with the case of agglomeration treatment of a conventional inorganic flocculant and a high-molecular flocculant, even if the amount of the inorganic flocculant added is small, sufficient effect.

1‧‧‧1st agglutination tank

2‧‧‧2nd agglutination tank

3‧‧‧Pressure flotation separation tank

Fig. 1 is a flow chart showing a water treatment method according to an embodiment.

Fig. 2 is a flow chart showing a water treatment method according to an embodiment.

Fig. 3 is a flow chart showing the processing operations of the first embodiment and the comparative example 1.

Hereinafter, embodiments of the water treatment method of the present invention will be described in detail.

[treated water]

In the present invention, as the water to be treated, water such as river water, industrial water, well water, water supply for the electronics industry, chemical factory drainage, and food factory drainage can be cited. The drainage can be organically treated biologically treated water.

[Cationic polymer flocculant having hydrophobic functional group]

The cationic polymer flocculant having a hydrophobic functional group is exemplified by the following (1) and (2), but is not limited thereto.

(1) A cationic monomer having a hydrophobic functional group is used as a necessary polymer flocculant

Examples of the cationic monomer having a hydrophobic functional group include dimethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylamide, and diethylamino B. (meth) acrylate, diethylaminopropyl (meth) acrylamide, N-methyl-N-ethylaminoethyl (meth) acrylate and N-methyl-N- A methyl chloride salt such as ethylaminopropyl (meth) acrylamide or the like. A cationic high-molecular flocculant having a hydrophobic functional group is a homopolymer or a copolymer copolymerizable with a vinyl monomer.

(2) A polymer flocculant containing a hydrophobic monomer and a cationic monomer as essential components

Examples of the hydrophobic monomer include N-methyl(N,N-dimethyl)acrylamide, acrylonitrile, styrene, methyl or ethyl (meth)acrylate.

Specific examples of the cationic monomer include a cationic vinyl monomer and a salt of dimethylaminoethyl (meth) acrylate. Or a 4-grade ammonium salt thereof, an acid salt of dimethylaminoethyl (meth) acrylamide or a 4-grade ammonium salt thereof, diallyldimethylammonium chloride or the like.

Further, (1) and (2) are all those which can copolymerize a nonionic monomer. Examples of the nonionic monomer include (meth)acrylamide, N-isopropylacrylamide, and N-methyl(N,N-dimethyl)acrylamide.

The polymerization method is not particularly limited, and a known radical polymerization method such as aqueous solution polymerization, solution polymerization, reverse phase suspension polymerization, photopolymerization, precipitation polymerization, and reverse phase emulsion polymerization can be applied.

<Polymer Properties of Cationic Polymer Flocculants Having Hydrophobic Functional Groups>

The weight average molecular weight of the cationic high-molecular flocculant having a hydrophobic functional group is preferably from 10 to 10,000,000, particularly from 3,000,000 to 10,000,000. Usually, as an index of molecular weight, the intrinsic viscosity using 1N-NaCl as a solvent is used. However, since the polymer having a hydrophobic functional group is precipitated in 1N-NaCl, the intrinsic viscosity of 0.1N-NaCl as a solvent can be used. At this time, it is preferably 10 d1/g or more at 30 °C.

The cationic unit is preferably 10 mol% or more, particularly 10 to 100 mol%, particularly preferably 50 to 100 mol%, based on the cationic monomer unit. When the amount is less than 10 mol%, the degree of cationicity is insufficient, so that the agglutination effect is lowered. The monomer unit of the cationic monomer having a hydrophobic functional group is 10 mol% or more, particularly 10 to 100 mol%, particularly preferably 50 to 100 mol%. The monomer unit of the hydrophobic monomer is 10 mol% or more, especially 10 to 80 mol%, particularly preferably 30 to 80 mol%.

<Formation of a product of a cationic high-molecular flocculant having a hydrophobic functional group>

It may be a powdery reverse phase emulsion or a suspension dispersion, and the form is not limited.

<Addition method of cationic high-molecular flocculant having hydrophobic functional group>

The form in which the polymer flocculant is added to the water to be treated is not particularly limited, but from the viewpoint of reactivity, it is preferred to add a solution dissolved in 0.05 to 1% by weight, particularly 0.1 to 0.5% by weight.

<Addition amount of cationic high-molecular flocculant having a hydrophobic functional group>

The amount of the polymer flocculant added is 0.1 to 100 mg/L with respect to the water to be treated, and particularly preferably 0.1 to 10 mg/L.

[Other flocculants]

The agglutination treatment can further be used in combination with an inorganic flocculant. Examples of the inorganic flocculant include iron-based flocculants such as ferric chloride and polyferric sulfate, aluminum flocculants such as aluminum sulfate, aluminum chloride, and polyaluminum chloride, calcium hydroxide, and magnesium hydroxide. Iron-based or aluminum-based flocculants are preferred. These inorganic flocculants may be used alone or in combination of two or more. The inorganic flocculant may be added before, after or simultaneously with the addition of the cationic high-molecular flocculant having a hydrophobic functional group.

The amount of the inorganic flocculant added varies depending on the properties of the water to be treated or the water quality, but it usually becomes 1 to 2000 mg/L, especially 50%. ~300mg / L is better.

Further, in combination with the anionic polymer flocculant or the nonionic polymer flocculant in combination with the properties of the water to be treated, the water quality of the agglomerated water or the effect of improving the pressure flotation separation property can be further improved. Examples of the anionic polymer flocculant include poly(meth)acrylic acid, a copolymer of (meth)acrylic acid and (meth)acrylamide, and an anionic polymer flocculant such as an alkali metal salt. . Examples of the nonionic polymer flocculant include nonionic organic polymer flocculants such as poly(meth)acrylamide.

The anionic or nonionic high-molecular flocculant may be added before, after or simultaneously with the addition of the cationic high-molecular flocculant having a hydrophobic functional group. The amount of the anionic or nonionic polymer flocculant to be added is usually from 0.01 to 10 mg/L, particularly preferably from 1 to 10 mg/L, as a solid content.

<pH adjustment>

The pH at the time of agglutination treatment is preferably pH 4 to 10 in the agglutination tank, and the pH is adjusted if necessary. The pH adjustment is suitably carried out using an acid such as hydrochloric acid (HCl) or sulfuric acid (H ₂ SO ₄ ) or a base such as sodium hydroxide (NaOH).

[Flotation separation]

The agglomerated treated water is then subjected to flotation separation, and solid-liquid separation produces aggregated flocs (floc). This flotation separation is carried out, and pressurized water of pressurized dissolved air is added to the agglomerated treated water to perform flotation separation in the flotation cell. in Various pressurized flotation separation devices can be used for this pressurized flotation separation.

[other processing]

Further, in the present invention, other treatments than the above may be used in combination in the subsequent stage of the pressurized flotation separation apparatus. For example, in order to remove residual dissolved organic matter, activated carbon treatment or membrane separation treatment may be performed.

[Processing device]

An example of the drainage treatment apparatus of the present invention will be described below with reference to the drawings. 1 and 2 are system diagrams showing an example of the drainage treatment apparatus of the present invention, wherein 1 and 2 denote agglomeration tanks, and 3 denotes a pressurized flotation separation tank. A stirring means is provided in each of the agglutination tanks.

In the wastewater treatment apparatus of Fig. 1, a cationic polymer flocculant having a hydrophobic functional group is added to the first agglutination tank 1 in the water to be treated, and an inorganic flocculant (for example, an iron flocculant) is added to the second aggregating tank 2; The agglutination treatment is carried out, the agglutination treatment water is added to the pressurized flotation separation tank 3, and pressurized water is added to perform flotation separation. The treated water is taken out from the lower portion of the tank, and the flotation material is taken out from the upper portion of the tank. Pressurized water may be added before the introduction of the flotation separation tank 3.

The apparatus shown in Fig. 2 is shown in Fig. 1, in which the order of addition of the cationic high-molecular flocculant having a hydrophobic functional group and the inorganic flocculant is reversed.

Further, the apparatus shown in FIGS. 1 and 2 is an example of the drainage treatment apparatus of the present invention, and the present invention is not limited to any of the illustrated methods. Alternatively, an inorganic flocculant may be substituted or an anionic or nonionic polymeric flocculant may be added together with the inorganic flocculant.

[Examples]

The present invention will be more specifically described below by way of examples and comparative examples. Further, in the following examples, as the cationic high-molecular flocculant having a hydrophobic functional group, a polymer of benzyl chloride-based quaternary DAM (B _Z Cl) of dimethylaminoethyl methacrylate was used. (Kuri farm PC797) of Kurita Industrial Co., Ltd. Further, the polymer of the benzyl chloride quaternary compound of the dimethylaminoethyl methacrylate has an intrinsic viscosity of 0.15-NaCl of 12.5 dl/g, and the weight average molecular weight determined by GPC measurement. It is 9 million.

[Example 1 and Comparative Example 1]

According to the test procedure shown in FIG. 3, the following simulated organic drainage was subjected to biological treatment as a raw water, and a coagulation-pressure flotation treatment was performed. Biological treatment becomes a continuous treatment. Aggregation and pressurized flotation are treated as batches using beakers and columns.

[simulated drainage]

BOD: 20mg/L (mixed water with glucose and acetic acid)

[biological treatment]

Sponge carrier fluidized bed

Reaction tank: 10L

Residence time: 1 hour

[raw water (biological treatment water)]

BOD: <5mg/L

SS: 10mg/L

Turbidity: 3.8 degrees

[Agglutination 1 agglutination conditions]

Batch agglutination in 1L beaker

Inorganic flocculant (38% ferric chloride): 100mg/L

The amount of the hydrophobic cationic polymer added was 0.2 mg/L (added in Example 1. Not added in Comparative Example 1).

Reaction time: 5 minutes

pH: 5.5

[Agglutination 2 agglutination conditions]

Batch agglutination in 1L beaker

Anionic polymer: acrylamide polymer, Kurita Industrial Co., Ltd. KURIFLOCK PA331

Anionic polymer addition amount: 0.5mg/L

Reaction time: 3 minutes

pH: 5.5

[Pressure flotation]

Batch pressurized flotation on a 1L column. Pure water is used for pressurized water.

Pressurizing pressure: 0.35MPa

Pressurized water ratio: 20%

[processing indicators]

The performance improvement evaluation of the pressurized flotation treatment was evaluated to produce the flotation rate of the scale and the scale strength, and the turbidity of the treated water. The results are shown in Table 1.

As shown in Table 1, it is considered that the flotation separation treatment is carried out more efficiently by the present invention, and the quality of the treated water is also improved.

1‧‧‧1st agglutination tank

2‧‧‧2nd agglutination tank

3‧‧‧Pressure flotation separation tank

Claims (4)

A water treatment method comprising: an agglutination reaction step of adding a flocculating agent to the agglomerated reaction of the water to be treated; and a water treatment method of a flotation separation step of solid-liquid separation of the agglomerated treated water flowing out from the agglutination reaction step, wherein The flocculating agent is a cationic high-molecular flocculant having a hydrophobic functional group. The water treatment method according to claim 1, wherein the cationic polymer flocculant is a cationic polymer having a hydrophobic functional group, or a monomer polymerizing at least a hydrophobic functional group, and a monomer having a cationic functional group. And get it. The water treatment method according to claim 1 or 2, wherein in the agglutination reaction step, an inorganic flocculant is further added. The water treatment method according to any one of claims 1 to 3, wherein an anionic or nonionic high-molecular flocculant is further added in the agglutination reaction step.