JPH0474592A - Water treatment method - Google Patents

Abstract

PURPOSE:To simply obtain good water treatment effect by using a mixture of xanthane gum and gum selected from guar gum, locust bean gum and tamarind gum mixed in a specific ration and a water-soluble aluminum salt. CONSTITUTION:A mixture of xanthane gum (A) and gum (B) selected from guar gum, locust bean gum and tamarind gum is prepared so that a mixing ratio (A)/(B) becomes 1/20 - 20/1. All of these gums are safe and harmless and generate no problem of environmental pollution. The mixture of these gums is added to water to be treated and a water-soluble aluminum salt is subsequent ly added thereto under proper stirring. After the water-soluble aluminum salt is added, the water to be treated is further stirred and allowed to stand to settle flocs formed by flocculation. A turbidity component may be separated and removed from the water to be treated using a proper solid-liquid separation means.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a water treatment method, particularly mud drainage generated during civil engineering works such as bridges and seawalls in rivers, lakes, etc., and gravel extraction work, or water treatment methods. The purpose of this invention is to provide a water treatment method that has excellent coagulation treatment effects and environmental safety in the treatment of muddy water generated during civil engineering work.

(Prior art) Conventionally, as a water treatment method, flocculation treatment methods using inorganic flocculants such as polyaluminum chloride, aluminum sulfate, and aluminum chloride, or organic synthetic polymer flocculants such as polyacrylamide-based and polyamine-based flocculants have been frequently used. There is.

However, in civil engineering work in rivers, lakes, etc., or construction work in the sea, there are issues such as environmental safety and pollution caused by residual flocculants, and the selection of the agent is important. The effect was also not satisfactory.

In other words, sewage generated during civil engineering works, etc. generally consists of fine mineral particles, and a method for treating this is a combination of an inorganic flocculant such as aluminum sulfate and an organic synthetic polymer flocculant such as polyacrylamide. Although it is well known that organic synthetic polymer flocculants have the best flocculating effect, they have poor decomposition properties and are currently almost unusable due to environmental pollution problems.

Furthermore, if this treatment is carried out using an inorganic flocculant alone, not only a large amount is required, but even if a large amount is added, a sufficient treatment effect cannot be obtained.

Further, safe and harmless natural polymer flocculants such as sodium alginate and carboxymethyl cellulose are known, but their flocculating effects are small and they have not been put to practical use.

(Problems to be Solved by the Invention) In view of the above circumstances, the present inventors have developed a method that is safe, harmless, does not pollute the environment, and has excellent treatment effects in the treatment of wastewater containing fine mineral particles such as civil engineering wastewater. In order to find a flocculant that has this property, we investigated using various agents and found that we used xanthan gum, which is generally used as a food thickener and water retention agent, is safe and harmless, and has very little environmental pollution. However, it was discovered that an excellent agglomerating effect can be obtained by a specific combination of this with other gums and water-soluble aluminum salts, leading to the completion of the present invention.

(Means for Solving the Problems) That is, the present invention relates to a water treatment method comprising using a mixture of xanthan gum and a gum selected from guar gum, locust bean gum or tamarind, and a water-soluble aluminum salt.

(Function) The xanthan gum used in the present invention is a type of fermented polysaccharide, and is produced by the microorganism xanthan dried eggplant (Xanthomonas campestris).
It is a natural gum that is made by fermenting glucose and refining the polysaccharides that accumulate outside the bacterial cells and turning it into powder.

Xanthan gum is commonly used as a thickener and water-retaining agent for foods such as frozen desserts, ham, and sausages, and is safe and harmless, and is a metabolite of microorganisms.
It is highly degradable in nature and does not cause problems such as environmental pollution.

Furthermore, other gums used in the present invention include guar gum,
Use locust bean gum or tamarind.

All of these gums are natural polysaccharides isolated from plants, and like the xanthan gum, they are harmless and do not cause environmental pollution problems.

Furthermore, examples of the water-soluble aluminum salt used in the present invention include polyaluminum chloride, aluminum sulfate, aluminum chloride, and the like.

In the present invention, water treatment is carried out using these agents. Regarding the treatment method, first, xanthan gum and a gum selected from guar gum, locust bean gum, or tamarind are mixed, and the water to be treated is stirred. Add this mixture while stirring.

Regarding the mixing ratio of these gums, the mixing ratio of xanthan gum (A) and gum (B) selected from guar gum, locust bean gum, or tamarind is (A)/(B) 1720 to 20/1. Mix it so that it is within the range of .

That is, in the present invention, the mixing ratio of these gums is particularly important, and if it deviates from this range, the effects of the present invention will not be obtained.

The amount of this mixture to be added to the water to be treated varies depending on the turbidity concentration, amount of turbidity, pH, etc. of the water to be treated, and cannot be generalized;
It is generally in the range of 1 to 50% by weight based on 1°03.

After addition of the gum mixture, the water-soluble aluminum salt is then added to it with moderate stirring.

The amount of the water-soluble aluminum salt added is approximately 0.1 to 5% by weight as Al2O,3 based on the turbidity (suspended mass) of the water to be treated.

After adding the water-soluble aluminum salt, the mixture is further stirred and allowed to stand, so that the flocs generated by coagulation settle. The turbid components may be separated and removed by using an appropriate solid-liquid separation means.

(Effects of the Invention) The water treatment method of the present invention allows simple and good water treatment effects to be obtained by the aggregation treatment method as described above.

In addition, since the gums used in the present invention, such as xanthan gum and guar gum, are derived from microorganisms or natural products, they are safe and harmless, and their degradability is also good, so they do not pollute the environment and are not polluted by rivers. It is ideal for water treatment in lakes, marshes, and sea areas.

Furthermore, in terms of its effectiveness, the method of the present invention has a much superior treatment effect compared to sodium alginate, carboxymethyl cellulose, etc., which have been known as water treatment agents in the past. This treatment effect is comparable to that obtained using synthetic polymer flocculants.

(Example) The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto.

In addition, in the present invention, all percentages are by weight unless otherwise specified.
shows.

Example 1 43g of kaolin (manufactured by Merck & Co., reagent grade) was added to 101g of tap water.
After stirring well, the mixture was left to stand for one day and used as a sample turbid water.

In addition, the turbidity of this turbid water during the flocculation test was 4000pp.
m, and the pH was 7.60.

Take 100 ml of the sample turbid water into a 100 ml graduated cylinder with a stopper, add the prescribed amount of the mixture (mixing ratio 471) of xanthan aluminum and other potent substances shown in Table 1, and The cylinder was capped and agitated 10 times.

To this, aluminum chloride (A120.310.2%
After adding 1,100 pp of 1,100 ppp (manufactured by Tamoto Kagaku Co., Ltd.), the mixture was further stirred by turning over 10 times.

After stirring, this was allowed to stand, and after 10 minutes, 20 ml of still water was collected and the turbidity was measured.

For comparison, a similar test was conducted using sodium alginate and carboxymethyl cellulose instead of the mixture of the xanthan column and other potent compounds, and the turbidity of the supernatant water was measured.

The results of these measurements are shown in Table 1.

Example 2 8 g of kaolin (manufactured by Merck & Co., reagent grade) was added to 10Q of tap water, thoroughly stirred, and left for one day to be used as a test turbid water.

In addition, the turbidity of this turbid water during the flocculation test was 700 ppm.
and the pH was 7.20.

100 ml of the sample turbid water was taken into a 100 ml graduated cylinder with a stopper, and a mixture of xanthancam (manufactured by Dainippon Pharmaceutical Co., Ltd.) and Akaim (manufactured by Dainippon Pharmaceutical Co., Ltd.) (mixing ratio 271) was added to this. A predetermined amount of the mixture was added, the graduated cylinder was stopped, and the mixture was stirred by inversion 10 times.

Furthermore, after adding predetermined amounts of various water-soluble aluminum salts shown in Table 2 to this, the mixture was further stirred by turning over 10 times.

After stirring, this was allowed to stand, and after 10 minutes, 20 ml of still water was collected and the turbidity was measured.

For comparison, a similar test was conducted without adding the water-soluble aluminum salt, and the turbidity of the supernatant water was measured.

The results of these measurements are shown in Table 2.

Example 3 43g of kaolin (manufactured by Merck & Co., reagent grade) was added to 10Q of tap water.
After stirring thoroughly, the mixture was left for one day and used as a sample turbid water.

In addition, the turbidity of this turbid water during the flocculation test was 4000pp.
m, and the pH was 7.60.

100 ml of the sample turbid water was taken into a 100 ml volume stopper graduated cylinder, and xanthan film (manufactured by Dainippon Pharmaceutical Co., Ltd.) and U-cas) heat/force (manufactured by Dainippon Pharmaceutical Co., Ltd.) were added to it. ) in the proportions shown in Table 3 was added in a predetermined amount, the graduated cylinder was stopped and the mixture was stirred by inverting 10 times.

To this, aluminum chloride (A1.0.10.2%,
After adding 1100 pp (manufactured by Taki Kagaku Co., Ltd.), the mixture was further stirred by turning over 10 times.

After stirring, this was allowed to stand, and after 10 minutes, 20 ml of still water was collected and the turbidity was measured.

For comparison, a similar test was conducted using xanthan column and locust beam column without mixing them, and each was used alone, and the turbidity of the supernatant water was measured.

The results of these measurements are shown in Table 3.

Example 4 A flocculation test was conducted using turbid water discharged as a result of dredging work in seawater (Kakogawafu, Hyogo Prefecture) as a sample turbid water.

In addition, the turbidity of this turbid water at the time of the test was 1 liter 1000 pp.
and the pH was 7.43.

500 ml of the sample turbid water was placed in a 500 ml female stopper cylinder, and a prescribed amount of the mixture of xanthan aluminum and other active materials shown in Table 4 (mixing ratio 1/4) was added to this. Then, the graduated cylinder was stopped and stirred by inversion 10 times.

Add aluminum chloride (A120310.2%) to this.
After adding 400 ppm of Taki Kagaku Co., Ltd., the mixture was further stirred by inversion 10 times.

After stirring, this was allowed to stand, and after 10 minutes, 20 ml of still water was collected and the turbidity was measured.

For comparison, commercially available synthetic polymer flocculants and polymers were used in place of the mixture of xanthan column and other polymers.

A similar test was conducted using only aluminum chloride, and the turbidity of the supernatant water was measured.

The results of these measurements are shown in Table 4.

Claims (2)

[Claims] (1) A water treatment method comprising using a mixture of xanthan gum and a gum selected from guar gum, locust bean gum or tamarind, and a water-soluble aluminum salt. (2) The mixture ratio of xanthan gum (A) and gum (B) selected from guar gum, locust bean gum, or tamarind is 1/20 to 20 (A)/(B).
The water treatment method according to claim 1, wherein the water treatment method is within the range of /1.