JPH0839077A - Treatment of nonionic surfactant-containing waste solution - Google Patents

Abstract

PURPOSE:To efficiently remove a nonionic surfactant contained in a waste soln. in low cost by adjusting a waste soln. containing a nonionic surfactant to predetermined temp. and applying flocculation treatment thereto to form flock containing the nonionic surfactant. CONSTITUTION:When a waste soln. containing a nonionic surfactant is treated, at first, an oil component is removed from the waste soln. and the pH of the waste soln. is adjusted to 3 or less by sulfuric acid if necessary and, subsequently, an alkali aq. soln. such as potassium hydroxide is added to neutralize the waste soln. to adjust the pH thereof to 8-11. Next, the waste soln. is adjusted to required temp. and a flocculant (org. polymeric flocculant) is added to the waste soln. to form floc which is, in turn, sedimented to be separated. The temp. of the waste soln. after pH adjustment is adjusted to temp. equal to or higher than the cloud point of the nonionic surfactant contained in the waste soln., pref., to a temp. range of the cloud point -80 deg.C to efficiently perform flocculation treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating alkaline, acidic and neutral effluent containing a nonionic surfactant. More particularly, the present invention relates to a method of treating effluent, especially when mixed with various nonionic surfactant detergents.

[0002]

2. Description of the Related Art In recent years, with the development of the petrochemical industry, the production amount of nonionic surfactants has dramatically increased, and its applications are wide-ranging, and in various fields including the chemical and textile industries. It is effectively used. On the other hand, it is also known that the surfactants that could not be sufficiently removed in the wastewater treatment flow out to the river and have a great adverse effect on the ecosystem.

Chemical oxygen demand (hereinafter referred to as COD) is generally used as a water quality indicator of a waste liquid containing a nonionic surfactant, and a waste liquid treatment method for reducing this COD is used. Known methods include an activated carbon adsorption method, an oxidative decomposition method using ozone and hydrogen peroxide, and a microbial treatment method. However, with regard to the above-mentioned treatment methods and, the running cost is very high, and therefore it is difficult to put them to practical use industrially, and regarding the treatment methods, the pH of the effluent to be treated, the amount of dissolved oxygen and the amount of sludge (SV ₃₀ ) etc. There is a problem that it is necessary to manage.

For example, when treating the drainage from the cleaning process of the metal surface, first the oil is removed from the drainage using an oil skimmer or the like, and then dissolved in the drainage by neutralization and coagulation treatment. A method is widely used in which the metal being precipitated is precipitated in the form of hydroxide or calcium salt, and then the surfactant remaining in the supernatant is removed by any one of the above treatment methods. ing. However, in these conventional methods and, since it is necessary to newly install equipment and control microorganisms, it is difficult to put them into practical use because the cost of drainage treatment is large.

Therefore, at present, no treatment method has been found which is capable of efficiently removing the nonionic surfactant contained in the effluent at low cost and reducing the COD of the effluent. is there.

[0006]

The present invention seeks to provide a method for treating alkaline and acidic effluents containing nonionic surfactants. That is, the present invention is intended to provide a treatment method for removing the nonionic surfactant contained in the effluent of the washing process using various nonionic surfactants to reduce the COD of the effluent. is there.

[0007]

Means for Solving the Problems As a result of extensive studies on means for solving the above-mentioned problems, the present inventors have found that the step of neutralizing a waste liquid containing a nonionic surfactant is carried out by the nonionic surfactant. It has been newly found that the nonionic surfactant in the effluent can be removed together with other contents and the COD of the effluent can be reduced by carrying out at a temperature above the cloud point of the agent, and the present invention is completed. Came to.

That is, the method for treating non-ionic surfactant-containing effluent of the present invention is such that, when treating the non-ionic surfactant-containing effluent, the non-ionic surfactant-containing effluent is treated at a temperature above the cloud point of the non-ionic surfactant. It is characterized in that it is prepared and subjected to a coagulation treatment to form an aggregate containing the nonionic surfactant, and the flocs containing the aggregate are allowed to settle and removed from the drainage. .

[0009]

The effluent to which the method of the present invention can be applied is not limited with respect to its components, concentration, pH, etc., as long as it is a general effluent containing a nonionic surfactant. Generally,
Alkaline cleaning effluent containing alkali metal ions such as Na ⁺ and K ⁺ and heavy metal ions, or SO ₄ ²⁻ ,
To acidic washing drainage, including PO ₄ ^3- and heavy metal ions, the present invention can be applied method. FIG. 1 shows an example of a treatment process of an acidic cleaning drainage by the method of the present invention, and FIG. 2 shows an example of a treatment process of an alkaline cleaning drainage by the method of the present invention.

As for the drainage treatment step and apparatus, the commonly used neutralization, coagulation-sedimentation method and apparatus can be used without any particular limitation. Generally, after removing the oil from the drainage, the drainage is adjusted to pH 3 or less with sulfuric acid or the like, if necessary, as shown in FIGS. 1 and 2, and then calcium hydroxide is added. , An alkaline aqueous solution such as sodium hydroxide is added to neutralize the drainage.
After adjusting the pH to 8-11 and then subjecting this drainage solution to the required temperature adjustment, add flocculants (organic polymer flocculants, inorganic flocculants, etc.) to the flocs formed. It is preferable to use a step of settling and separating.

The most important point in the method of the present invention is the control of the liquid temperature when the waste liquid containing the nonionic surfactant is coagulated. That is, it is necessary to adjust the temperature of the drainage to a temperature not lower than the cloud point of the nonionic surfactant contained therein and to subject it to a coagulation treatment. This aggregation treatment temperature is
The temperature is equal to or higher than the cloud point of the nonionic surfactant contained in the drainage, preferably the cloud point to 80 ° C.

The cloud point of the nonionic surfactant varies depending on its type and composition, but is generally 15 ° C to 80 ° C.
Many are within the range.

In the method of the present invention, the neutralization and coagulation treatment temperature is defined to be equal to or higher than the cloud point of the nonionic surfactant contained in the effluent so that the nonionic surfactant solute molecule is dehydrated. Shows a peculiar behavior in that it loses water solubility and precipitates, and the precipitated nonionic surfactant forms flocs with metal hydroxide, heavy metal ions, or acid ions together with the coagulant added. It can be allowed to settle. Therefore, when the effluent is neutralized and coagulated at a temperature below the cloud point, flocs are less likely to be formed, and the removal efficiency of the nonionic surfactant decreases.

On the other hand, when the neutralization / aggregation treatment temperature exceeds 80 ° C., the removal of the nonionic surfactant in the waste liquid is sufficient, but the energy cost for maintaining the liquid temperature is high. This can be problematic because it is expensive and not economical.

For the coagulation treatment used in the method of the present invention, it is sufficient to use a conventionally recognized effective drainage solution. For example, when the nonionic surfactant-containing drainage liquid is an alkaline liquid containing an alkali builder such as sodium carbonate and sodium phosphate, and a chelating agent for various metal ions, the pH of the drainage liquid is adjusted. After adjusting to 8 to 11, ferric chloride, aluminum sulfate, polyaluminum chloride, polyacrylamide,
Also, a flocculant selected from polyacrylic tester and the like may be used. When it is an acidic liquid containing an acid builder such as sulfuric acid and phosphoric acid, and a chelating agent for various metal ions, the pH of this effluent is adjusted to 8 to 11 and the aggregating agent is added thereto. It may be added. Furthermore, when the waste liquid to be treated has a pH of 8 to 11, the required coagulant may be added without the pH adjusting step.

[0016]

The present invention will be described in detail with reference to the following examples. In the following examples, a pH 2 acidic cleaning drainage containing metal ions and a pH 10 alkaline cleaning drainage containing metal ions are used as typical examples, but the method of the present invention is limited to these drainage treatments. Instead, it is also applicable in the case of neutral drainage and also in the case of drainage containing no metal ions.

[Test Drainage] An acidic cleaning drainage (pH 2) having the composition shown in Table 1 and an alkaline cleaning drainage (pH 10) having the composition shown in Table 2 were used.

[0018]

[Table 1]

[0019]

[Table 2]

[Test Method] <When Treating Acid Wash Drainage> The acid wash drainage shown in Table 1 was added to the non-ionic substances described in Examples 1 to 5 and Comparative Examples 1 to 2 and 4 to 5 respectively. A reactive surfactant was added to make the total amount of drainage 0.9 liter. This is subjected to drainage treatment in the step shown in FIG. 1, and the total organic carbon content measuring device (TOC-500, manufactured by Shimadzu Corporation) is used for the supernatant liquid after neutralization and coagulation / precipitation.
Was used to measure the total amount of organic carbon (hereinafter referred to as TOC), and the COD was measured using the JIS water quality test method.

<Method of Treating Alkaline Cleaning Effluent> To the alkaline cleaning effluent shown in Table 2, the nonionic surfactant described in each of Examples 6 to 7 and Comparative Examples 3 and 6 was added, The total amount of drainage was 0.9 liter. Figure 2
The drainage treatment was performed in the step shown in, and the TOC and COD of the supernatant were measured by the same method as described above.

Example 1 0.2 g of the following nonionic surfactant (1) was added to the acid cleaning effluent of Table 1, and the effluent temperature was adjusted to 40 ° C.
Drainage treatment was performed at this temperature, and TOC and COD of the supernatant liquid after coagulation and sedimentation were measured. Nonionic surfactant (1): polyoxyethylene polyoxypropylene nonylphenol ether (cloud point 35 ° C.) 0.2 g The measurement results are shown in Tables 3 and 4.

Example 2 0.2 g of the same nonionic surfactant (1) as in Example 1 was added to the acidic cleaning drainage liquid of Table 1, the drainage temperature was adjusted to 60 ° C., and the drainage was performed at this temperature. Liquid treatment was applied. The TOC and COD of the supernatant after coagulation and precipitation were measured. The measurement results are shown in Tables 3 and 4.

Example 3 0.2 g of the following nonionic surfactant (2) was added to the acidic cleaning drainage liquid of Table 1 and the drainage temperature was adjusted to 40 ° C.
This was subjected to drainage treatment. The TOC and COD of the supernatant after coagulation and precipitation were measured. Nonionic surfactant (2): polyoxyethylene polyoxypropylene nonylphenol ether (clouding point 35 ° C.) 0.1 g polyoxyethylene polyoxypropylene nonyl alcohol ether (clouding point 17 ° C.) 0.1 g ───── ──────── Cloud point 26 ℃ 0.2g Table 3 and Table 4 show the measurement results.

Example 4 0.2 g of the same nonionic surfactant (2) as in Example 3 was added to the acid cleaning drainage liquid of Table 1 and the drainage temperature was adjusted to 60 ° C. Liquid treatment was applied. The TOC and COD of the supernatant after coagulation and precipitation were measured. The measurement results are shown in Tables 3 and 4.

Example 5 0.2 g of the same nonionic surfactant 2 as in Example 3 was added to the acid cleaning drainage liquid of Table 1, the drainage temperature was adjusted to 80 ° C., and the drainage treatment was performed. Was applied. The TOC and COD of the supernatant after coagulation and precipitation were measured. The measurement results are shown in Tables 3 and 4.

Example 6 0.18 g of the following nonionic surfactant (3) was added to the alkaline cleaning effluent shown in Table 2, the effluent temperature was adjusted to 50 ° C., and the effluent treatment was performed. . The TOC and COD of the supernatant after coagulation and precipitation were measured. Nonionic surfactant (3): polyoxyethylene nonylphenol ether (cloud point 64 ° C.) 0.10 g polyoxyethylene polyoxypropylene monopolyhydric alcohol ether (cloud point 24 ° C.) 0.08 g ────── ──────── Cloud point 46 ℃ 0.18g Table 3 and Table 4 show the measurement results.

Example 7 0.18 g of the same nonionic surfactant (3) as in Example 6 was added to the alkaline cleaning effluent shown in Table 2 and the effluent temperature was adjusted to 70 ° C. Liquid treatment was applied. The TOC and COD of the supernatant after coagulation and precipitation were measured. The measurement results are shown in Tables 3 and 4.

Comparative Example 1 0.2 g of the same nonionic surfactant (1) as in Example 1 was added to the acid cleaning drainage liquid of Table 1, and the temperature of this drainage liquid was 20 ° C.
Drainage treatment was performed at ° C. The TOC and COD of the supernatant after coagulation and precipitation were measured. The measurement results are shown in Tables 3 and 4.

Comparative Example 2 0.2 g of the same nonionic surfactant (2) as in Example 3 was added to the acidic cleaning drainage liquid of Table 1, and the temperature of this drainage liquid was 20 ° C.
Drainage treatment was performed at ° C. The TOC and COD of the supernatant after coagulation and precipitation were measured. The measurement results are shown in Tables 3 and 4.

Comparative Example 3 To the alkaline cleaning effluent shown in Table 2, 0.2 g of the same nonionic surfactant (3) as in Example 6 was added, and the effluent was subjected to a effluent treatment at a temperature of 35 ° C. did. The TOC and COD of the supernatant after coagulation and precipitation were measured. The measurement results are shown in Table 3,
It shows in Table 4.

Comparative Example 4 0.2 g of the same nonionic surfactant (1) as in Example 1 was added to the acidic cleaning drainage liquid of Table 1, and the temperature of this drainage liquid was 20 ° C.
Drainage treatment was performed at ° C. Then, the supernatant after coagulation and sedimentation is subjected to microbial treatment under the following conditions,
OC and COD were measured. <Microorganism treatment conditions> Microorganism concentration (MLSS): 3000 ppm (aerobic treatment surplus sludge at sewage treatment plant) Dissolved oxygen concentration: 1 ppm Treatment temperature: 20 ° C Treatment time: 24 hours The measurement results are shown in Tables 3 and 4.

Comparative Example 5 0.2 g of the same nonionic surfactant (2) as in Example 3 was added to the acid cleaning drainage liquid of Table 1, and this drainage liquid was subjected to drainage treatment at 20 ° C. . The supernatant after coagulation and precipitation was subjected to activated carbon adsorption treatment (batch type) under the following conditions, and the TOC and COD of the treated liquid were measured. <Activated carbon adsorption treatment conditions> Activated carbon raw material: Yashigara (manufactured by Kuraray Chemical Co., Ltd.) Mesh: 10/32 granules Addition amount: 5000 ppm Treatment temperature: 20 ° C Treatment time: 30 minutes Stirring speed: 100 rpm The measurement results are shown in Table 3, It shows in Table 4.

Comparative Example 6 0.18 g of the same nonionic surfactant (3) as in Example 6 was added to the alkaline cleaning effluent shown in Table 2, and this effluent was subjected to drainage treatment at 35 ° C. . The supernatant after coagulation and precipitation was subjected to activated carbon adsorption treatment (batch type) under the same conditions as in Comparative Example 5, and the TOC and COD of the treated liquid were measured. The measurement results are shown in Tables 3 and 4.

[0035]

[Table 3]

[0036]

[Table 4]

As shown in Tables 3 and 4, by performing the drainage treatment according to the methods of Examples 1 to 7 of the present invention, compared to Comparative Examples 4 to 6 according to the conventional method, non-ionic equivalent to or more than non-ionic. It was possible to reduce the concentration of the cationic surfactant and further reduce COD. On the other hand, as shown in Comparative Examples 1 to 3, when the liquid temperature during the neutralization and coagulation-sedimentation treatment is lower than the cloud point of the nonionic surfactant, and the microbial treatment and the activated carbon adsorption treatment are not performed. However, the nonionic surfactant could not be removed efficiently, and the COD was not sufficiently reduced.

[0038]

As is apparent from the above description, when treating the waste liquid containing the nonionic surfactant, the waste liquid containing the nonionic surfactant is treated at a temperature higher than the cloud point of the nonionic surfactant contained in the waste liquid. By subjecting the waste liquid to neutralization and coagulation treatment, aggregates containing the nonionic surfactant can be settled and removed as flocs, which allows the nonionic surfactant in the waste liquid to be cost-effective. Significantly reduces the concentration of COD and COD
It has become possible to reduce.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of steps in a case where the method of the present invention is applied to an acidic cleaning drainage liquid.

FIG. 2 is a block diagram showing an example of steps in the case of applying the method of the present invention to alkaline cleaning drainage.

Claims (3)

[Claims] 1. A non-ionic surfactant-containing drainage liquid is adjusted to a temperature not lower than the cloud point of the non-ionic surfactant and subjected to a coagulation treatment to contain the non-ionic surfactant. A method for treating a nonionic surfactant-containing effluent, which comprises forming an agglomerate and allowing the agglomerate-containing flocs to settle and be removed from the effluent. 2. The processing method according to claim 1, wherein the temperature of the non-ionic surfactant-containing waste liquid is adjusted within the range of the cloud point of the non-ionic surfactant to 80 ° C. 3. The pH of the effluent containing the nonionic surfactant
Is adjusted within the range of 8.0 to 11.0.