JPS588919B2 - Odei Hensei Taino Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a modified sludge, and more particularly to a method for producing a modified sludge with great utility value by reacting surplus sludge with monohalogenated acetic acid or the like.

2. Description of the Related Art Treatment equipment using activated sludge has been widely used as a measure to prevent environmental pollution caused by various types of industrial wastewater.

However, although there is a large amount of surplus sludge discharged from this equipment, there is almost no use for it, and at present, this sludge is mainly incinerated or disposed of in landfills, and there is a small amount of waste sludge used in cement concrete, etc. The only known use of hard compositions is as fillers, fertilizers or feeds.

Therefore, in view of the above-mentioned current situation, the present inventors conducted intensive research to develop a way to effectively utilize surplus sludge. They discovered that the body is effective for various purposes and completed the present invention.

That is, the present invention provides a method for producing a modified sludge, which is characterized by reacting sludge with monohalogenated acetic acid or its salts in the presence of an alkali.

Although the type of sludge used in the method of the present invention is not particularly limited, surplus sludge produced when industrial wastewater is treated by an activated sludge method is usually used.

Although such sludge may be used as it is, it is preferable to use sludge in the form of a water-containing paste or dried sludge obtained by centrifuging the sludge, filtering it through an oven, dehydrating it, and concentrating it.

Next, monohalogenated acetic acid or its salts react with the sludge, carboxymethylating the sludge and converting it into a modified sludge. In the reaction with sludge, the amount of monohalogenated acetic acid or its salts used is generally 0.1 to 3.0 mol, particularly preferably 0.2 to 1.5 mol, per 100 g of dry sludge.

If the amount is less than 0.1 mol, some reaction products are produced which are insoluble in water, and such products have low utility value, so that the object of the present invention cannot be achieved.

Note that even if 30 mol or more is added, the effect corresponding to the amount added cannot be achieved, which is economically disadvantageous.

Examples of the monohalogenated acetic acid used in the present invention include monochloroacetic acid, monobromoacetic acid, and monoiodoacetic acid, but monochloroacetic acid is advantageous for economical reasons.

Examples of the salts of monohalogenated acetic acid include sodium salts and potassium salts of the monohalogenated acetic acid.

Furthermore, it is advantageous for the process of the invention to carry out the reaction in the presence of an alkali.

Alkali has the effect of promoting carboxymethylation of sludge, and the amount used varies depending on the type of alkali and the type of monohalogenated acetic acid or its salts as the carboxymethylating agent, and cannot be uniquely determined. No, but usually 0.1 to 100g of dry sludge
The proportion is 5.0 mol, preferably 0.2 to 3.0 mol.

Note that the alkali used here is not particularly limited, but caustic soda, caustic potash, etc. are commonly used.

Further, the reaction of the present invention is preferably carried out in a solvent.

The solvent is not particularly limited, but water or a water-containing organic solvent is preferably used.

The water-containing organic solvent may be one with relatively low water content, such as benzene, methylene chloride, or amyl alcohol, or one that is highly compatible with water, such as acetone, ethanol, or impropanol. There is no harm in using it.

The reaction temperature varies depending on the type of monohalogenated acetic acid or its salt or alkali, solvent, etc., and the degree of carboxymethylation of the sludge, but is usually 0 to 1.
Within the range of 00℃, especially when water is used as a solvent, 7
The temperature is preferably 0°C or lower.

If the temperature is too high, the monohalogenated acetic acid or its salt will be decomposed by the alkali to form glycolic acid or its salts, and the desired reaction will not proceed sufficiently.

After the reaction is completed, the reactive product sludge is converted into carboxylic acid. When the methylated sludge denatured product is used as a medium, alcohol,
It can be separated and recovered as an alkali metal salt by precipitation using an organic solvent such as acetone, or as a free acid by acid precipitation using sulfuric acid or the like.

On the other hand, when a water-containing organic solvent is used as a medium, the reaction product can be separated and recovered as an alkali metal salt by 5F filtration.

In any case, if you want to obtain a reaction product with high protein content, use sulfuric acid. The pH may be adjusted to 7 or lower, preferably 2 to 5, using hydrochloric acid or the like, and then separated and recovered.

The reaction product thus obtained can be purified by washing with an aqueous solution of an 80-90 alcohol, for example methanol, or by converting the reaction product into an insoluble acid form and washing with water.

The modified sludge thus obtained has various properties; for example, an aqueous solution containing the modified product has a relatively low viscosity and has excellent dispersion of kaolin, etc., so it can be used as a protective colloid agent. can.

In addition, when the modified product contains a particularly large amount of protein, its aqueous solution has excellent foaming properties, so it can be used as a fire extinguisher.
It can be effectively used as a foaming agent such as a foaming agent for ore flotation, or as a spilled oil treatment agent.

As described above, the method of the present invention can be said to be extremely valuable as it opens the door to effective use of resources by converting surplus sludge, which has little utility value, into a modified product that can be used for a wide variety of purposes.

Next, the method of the present invention will be explained in more detail by way of examples.

Example 1 500ml of sludge heaste 200g (dry weight 2.0g)
Pour into a three-neck flask, add 100 ml of water to disperse well, then add 20 g of caustic soda and 15 g of monochloroacetic acid.
was added and reacted at 50° C. for 6 hours with stirring.

The reaction was then cooled to 20°C, adjusted to pH 3 with sulfuric acid, and left overnight at room temperature.

The resulting precipitate was collected by centrifugation, washed with 100 ml of water, suspended in 50 ml of water, and adjusted to pH 7 with caustic soda.
13g of pale yellow water-soluble powder by freeze-drying
I got it.

The substance has a protein content of 25% by weight and a CH2COONa group content of 10% by weight (measured by the naphthalene diol method).
It is completely soluble in water at pH 7 and has a viscosity of 12 cp (
1 aqueous solution, 25° C., and a B-type viscometer at 6 Orpm).

In addition, one batch of the above reaction product was added to a 0.5% aqueous suspension of kaolin and allowed to stand overnight at 25°C, but there was no change in the dispersion state of kaolin, and good dispersibility was observed.

Example 2 20 g of dried sludge with a protein content of 39 was placed in a 500 ml three-neck flask, and 200 m of dried sludge with a protein content of 95 was added.
A? was added and maintained at 10 to 20°C, and 18 ml of a 50% caustic soda aqueous solution and 5 g of monochloroacetic acid were added.
Stir for hours.

Next, the mixture was heated in a 70° C. water bath and reacted for 3 hours while stirring.

After the reaction was completed, it was cooled to 20°C and adjusted to pH 4 with hydrochloric acid.
The precipitate was collected from house to house, washed with an 80% methanol aqueous solution, further suspended in an 80% methanol aqueous solution, adjusted to pH 7 with caustic soda, and after pH filtration, dehydrated with 99.5% methanol and air-dried to form a pale yellow aqueous solution. 15 g of powder was obtained.

The substance has a protein content of 33% by weight and a -CH2COONa group content of 13% by weight (values measured by the naphthalene diol method).
It is completely soluble in water at pH 7 and has a viscosity of 9 ep (1
% aqueous solution, 25°C, B type viscometer 6orpm. (measured value).

Further, the foaming power of a 1% aqueous solution of the above reaction product at 25° C. was 170 mm (according to the Ross Miles method).

Claims (1)

[Claims] 1. A method for producing modified sludge, which comprises reacting sludge with monohalogenated acetic acid or its salts in the presence of an alkali.