JPH06104236B2 - Deodorant for dehydrated sludge cake and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to various industrial wastewater, sewage,
The present invention relates to a deodorant for a dehydrated sludge cake and a method for producing the same, which reduces the generation of a bad odor in a sludge cake obtained by dehydrating organic sludge generated by human waste treatment or the like and suppresses the generation of a bad odor over a long period of time.

[0002]

2. Description of the Related Art Various industrial wastewater containing organic matter, sewage,
The human waste treatment is biologically or physically and chemically treated, but in that case, a large amount of sludge concentrated by solid-liquid separation is generated. These sludges are usually added with a polymer flocculant and dehydrated with an appropriate dehydrator such as a centrifuge, a filter press, a belt press and a screw press to obtain a water content of 70-80.
% Sludge cake.

The sludge cake is temporarily stored and then transported for landfill or incineration. In this case, since it contains organic matter, it has a bad odor due to putrefaction. It is a very serious problem. The sludge cake rots mainly during storage due to the action of anaerobic bacteria and produces various malodorous substances. There are many kinds of these malodorous substances, and typical ones among them are hydrogen sulfide containing nitrogen and sulfur, mercaptan, ammonia, and amines.

According to the Offensive Odor Control Law (enforced in 1972), the government uses the main offensive odors in business establishments and living environments as follows.
Currently, 12 substances with a bad smell are specified.

Among these, especially ammonia, hydrogen sulfide,
Methyl mercaptan has a strong odor, and each business site, sewage treatment plant, and human waste treatment plant are required to deal with it.

[0006] As the value of society becomes higher and higher due to changes in social conditions, the problem of malodor in life is everywhere, and various deodorants have been proposed to cope with them. Among these, commercially available deodorants are mainly as follows.

(1) Masking agent using aromatic substance (sensory deodorant) (2) Deodorant using enzyme (3) Deodorant by adsorption using activated carbon, zeolite, etc. (4) Oxidizing agent , Deodorant using reducing agent (sodium hypochlorite, sodium sulfite, ozone) (5) Deodorant by neutralizing acid agent, alkaline agent, etc. (6) Deodorant by vegetable oil extracted from natural products Agent (7) Deodorant by addition reaction of methacrylic acid ester, maleic acid ester, etc. (8) Deodorant by condensation reaction using aldehydes such as glyoxal However, at present, these deodorants include There are advantages and disadvantages. It is effective only in a closed place such as a refrigerator or a car, is effective only for a very weak odor, is unstable over time, and is dangerous to handle.

When considering a deodorant, it is difficult to deal with the malodor treatment under a wide variety of environments by a uniform method, but it has a strong odor like sludge and is generated in an open state. In the case of considering deodorization against, it is the actual situation that existing deodorants do not work at all. Therefore, there is a demand for a deodorant that has a strong deodorizing effect, acts concentrated on the sludge cake, and suppresses the odor. The deodorant added to sludge and flowing out to the water system during solid-liquid separation requires a huge amount of addition and is not economically suitable for practical use. In addition, the amount of separated water may be adversely affected when it enters the post-process of wastewater treatment, and the amount of addition is limited.

[0009]

When considering deodorization of sludge cake, there are the following problems.

(1) Among ordinary substances, a particularly strong malodor is generated.

(2) When the sludge is dehydrated, a large amount of water flows out, so that the effect cannot be sufficiently exhibited unless the deodorant moves to the solid component (sludge cake) side.

(3) Since the sludge cake is a semi-solid okara, it is difficult to uniformly mix the deodorant with the sludge cake.

(4) The deodorant does not uniformly disperse in the sludge cake, and if there is bending, no offensive odor is generated.

(5) It is a problem if the water content of the sludge cake is deteriorated. If possible, those having a reduced water content are preferable.

(6) A substance capable of taking both an alkaline malodorous substance and an acidic malodorous substance is preferable.

(7) The method of adding the deodorant must be simple. If possible, those that can be added using existing equipment are preferable.

(8) A sludge cake having a wide variety of properties can be supported by slightly modifying the formulation based on the basic formulation.

The present invention was devised with the object of providing a deodorant and a method for producing the same that solve these problems.

[0019]

Means for Solving the Problems A solution of 1,2-benzisothiazolin-3-one salt in ethylenediamine or other organic or inorganic alkaline substance solution and ferric sulfate or the like 3
Of a divalent iron salt aqueous solution is mixed with an appropriate amount of coprecipitated hybrid fine particle colloid, or 1,2-benzisothiazolin-3-one salt of ethylenediamine or other organic or inorganic alkaline substance and dipropylene glycol, etc. Aqueous solution with other glycols and ferric sulfate, etc.
Of an iron-valent aqueous solution of a valent iron salt is composed of co-precipitated hybrid fine particle colloids produced by mixing each in an appropriate amount, and further an aqueous solution of 1,2-benzisothiazolin-3-one salt of ethylenediamine or other organic or inorganic alkaline substance, sulfuric acid. Consisting of coprecipitated hybrid fine particle colloid produced by mixing an appropriate amount of an aqueous solution of a trivalent iron salt such as ferric iron and an inorganic acid salt such as sulfuric acid of a reducible polyvalent metal or an organic acid salt such as gallic acid Alternatively, 1,2-benzisothiazoline-3-
An on-salt aqueous solution of ethylenediamine or other organic or inorganic alkaline substance and other glycol such as dipropylene glycol, an aqueous solution of a trivalent iron salt such as ferric sulfate, and an inorganic salt of a reducible polyvalent metal such as sulfuric acid. Alternatively, it is composed of a coprecipitated hybrid fine particle colloid produced by mixing appropriate amounts of organic acid salts such as gallic acid.

Further, as a production method, an aqueous solution of 1,2-benzisothiazolin-3-one salt of ethylenediamine or other organic or inorganic alkaline substance and other glycol such as dipropylene glycol, and 3 of ferric sulfate or the like.
-Valent iron salt aqueous solution is mixed to produce a coprecipitated hybrid fine particle colloid, and the colloid is adjusted to pH 6-8, or
After adjustment, a dispersant is added and mixed to obtain a deodorant.

The organic or inorganic alkaline substance of the deodorant is for dissolving a salt of 1,2-benzisothiazolin-3-one in an aqueous solution, and this dissolving operation is carried out by adding other glycol such as dipropylene glycol to the inorganic alkaline. It can be increased by using it together with a substance or the like.

Further, as an inorganic acid salt or an organic acid salt, two or more of chromium, cobalt, copper, iron, lead, manganese, mercury, molybdenum, nickel, palladium, platinum, tin, titanium, tungsten, vanadium and the like are used. There are inorganic acid salts such as sulfuric acid, hydrochloric acid and nitric acid which are reducible polyvalent metals having a valence, or organic acid salts such as gallic acid, malic acid and fumaric acid which are polyvalent metals such as chromium.

There are inorganic acids or organic acids used for pH adjustment, and examples of the organic acids include citric acid, isocitric acid, lactic acid, tartaric acid, malic acid, hydroxybutyric acid, monoethyl tartrate, monoethyl citrate, phosphoric acid and the like. Can be mentioned.

Further, examples of the inorganic acid include sulfuric acid, hydrochloric acid, nitric acid, sulfonic acid and the like.

As the dispersant, in addition to the formalin condensate of sodium naphthalenesulfonate, a salt of a copolymer of a vinyl compound and maleic acid, a polyacrylic acid salt, an alginic acid salt, carboxymethyl cellulose or the like can be used.

[0026]

The present invention is characterized in that the constituent components of the deodorant are water-insoluble ultrafine particle colloids, and as a result, they are completely and uniformly dispersed in sludge.

After dewatering, the mixture is transferred to the cake side in a state of being completely and uniformly mixed.

Since the deodorant component is ultrafine particles, the surface area is large and the effect is enhanced.

The deodorizing effect lasts for a long time.

Drainage at the time of dehydration is promoted and the water content is lowered (action of iron salt).

Although the detailed mechanism of action of this deodorant is unknown,
Chemical reaction by functional group of 1,2-benzisothiazolin-3-one salt, reaction with sulfur compound by iron (particularly, trivalent iron is partially reduced to divalent iron when contacted with anaerobic sludge, (Reacts with sulfur compounds) or chemical reaction between various metals in the metal salt and the malodorous substance.

Further, 1,2-benzisothiazoline-3-
The bactericidal action of on-salt is considered.

Although a polymer flocculant was used in the deodorant test, when an organic acid such as citric acid or an inorganic acid was used when the polymer flocculant was dissolved, it was found that among the alkaline malodorous substances such as ammonia and amines. It is possible that the odor occurs, and the polymer flocculant also has the effect of suppressing the malodor due to the reaction of the amino group with the malodorous substance and the clathrate action of the polymer. It is considered that it has contributed.

[0034]

[Examples] Production examples of the deodorant for dehydrated sludge cake of the present invention are shown below.

Production Example 1. Ferric sulfate (41% aqueous solution) 1
2.2 parts by weight were dissolved in 146 parts by weight of deionized water and the temperature was kept at 40 ° C. 1,2-benzisothiazoline-
A solution of 3-one sodium salt in a dipropylene glycol aqueous solution (1,2-benzisothiazolin-3-one sodium salt component 20 wt.%) [I. C. I. Company
50 parts by weight of Proxel GXL] was added dropwise to the above aqueous solution with stirring. PH = with sodium hydroxide and sulfuric acid
After adjusting to 7.0, a condensate of sodium naphthalenesulfonate was added as a dispersant, and a rotary homogenizer was operated at 10,000 rpm. p. m. It was treated under the condition of × 3 minutes to obtain a stable colloidal dispersion.

Production Example 2. Ferric sulfate (41% aqueous solution)
6.1 parts by weight, of copper sulfate pentahydrate (CuSO ₄ · 5H ₂ O)
6.1 parts by weight were dissolved in 146 parts by weight of deionized water and the temperature was kept at 40 ° C. 1,2-benzisothiazoline-
A solution of 3-one sodium salt in a dipropylene glycol aqueous solution (1,2-benzisothiazolin-3-one sodium salt component 20 wt.%) [I. C. I. Company
50 parts by weight of Proxel GXL] was added dropwise to the above aqueous solution with stirring. PH = with sodium hydroxide and sulfuric acid
After adjusting to 7.0, a condensate of sodium naphthalenesulfonate was added as a dispersant, and a rotary homogenizer was operated at 10,000 rpm. p. m. It was treated under the condition of × 3 minutes to obtain a stable colloidal dispersion.

Deodorization test with sludge 1. A Sludge from sewage treatment plant Alkalinity 450 mg CaCO ₃ / l pH 5.2 TS 2.65% Deodorant addition amount 520 ppm Coagulant addition amount 260 ppm

[0038]

[Table 1]

2. B Sludge from human waste treatment plant Alkalinity 3290 mg CaCO ₃ / l pH 7.8 TS 2.73% Deodorant addition amount 380 ppm Flocculant addition amount 190 ppm

[0040]

[Table 2]

The test method was performed in the following order.

1) A deodorant is dissolved in a predetermined amount, and citric acid monohydrate set to each concentration is dissolved therein. Furthermore, a polymer flocculant (using dimethylaminoethyl methacrylate methyl chloride quaternary salt polymer) was added to the above in 0.1
Adjust to% concentration and dissolve.

2) Add 300 ml of each sample slurry to 50
Collect in a 0 ml beaker.

3) To the slurry of 2) was added each amount of the one dissolved in 1), and 1500 r.p.m. p. m. Stir with a jar tester for 2 minutes.

4) No. 1 Filter with filter paper and collect a fixed amount of filtrate.

5) Sludge cake 80 obtained in 4)
g in a 300 ml Erlenmeyer flask and tightly stopper with a rubber stopper with three cocks.

6) The Erlenmeyer flask in 5) is left for 18 hours in a 36 ° C. water bath.

7) The amount of gas generated from the Erlenmeyer flask is measured by one of the three cocks.

8) After 18 hours, measure the odorous gas concentration in the Erlenmeyer flask with a gas detector tube.

[0050]

EFFECTS OF THE INVENTION The deodorant of the present invention is characterized in that its deodorant component is in the form of an ultrafine particle colloid, so that it can be rapidly and uniformly mixed with sludge, and when dewatered, the sludge residue Move to sludge cake. The deodorant component is evenly mixed in the sludge cake, and due to the large effective surface area because the particles are fine particles, it strongly reacts with the malodorous component,
Deodorize the cake intensively. For that reason,
There is an advantage that it does not flow into desorbed water during dehydration and does not affect the post-process of wastewater treatment.

In addition, as a manufacturing method, a deodorant which can be expected to have a deodorizing effect can be obtained, and a product having no functional deterioration over time can be obtained by adjusting pH, and dispersion stability can be obtained by adding and mixing a dispersant. You can get the product.

Claims (6)

[Claims] 1. An appropriate amount of a 1,2-benzisothiazolin-3-one salt, an aqueous solution of an ethylenediamine or other organic or inorganic alkaline substance, and an aqueous solution of a trivalent iron salt such as ferric sulfate is mixed together. Deodorant for dehydrated sludge cake consisting of co-precipitated hybrid fine particle colloid. 2. An aqueous solution of 1,2-benzisothiazolin-3-one salt of ethylenediamine or other organic or inorganic alkaline substance and other glycol such as dipropylene glycol, and a trivalent iron salt such as ferric sulfate. Deodorant for dehydrated sludge cake consisting of coprecipitated hybrid fine particle colloid produced by mixing appropriate amount of aqueous solution. 3. A 1,2-benzisothiazolin-3-one salt aqueous solution of an ethylenediamine or other organic or inorganic alkaline substance, an aqueous solution of a trivalent iron salt such as ferric sulfate, and a sulfuric acid of a reducible polyvalent metal. The deodorant for a dehydrated sludge cake, which comprises a coprecipitated hybrid fine particle colloid produced by mixing an appropriate amount of each of the inorganic acid salt or the organic acid salt such as gallic acid. 4. An aqueous solution of 1,2-benzisothiazolin-3-one salt of ethylenediamine or other organic or inorganic alkaline substance and other glycol such as dipropylene glycol, and a trivalent iron salt such as ferric sulfate. A deodorant for a dehydrated sludge cake, which comprises a coprecipitated hybrid fine particle colloid produced by mixing an aqueous solution and an inorganic salt such as a reducible polyvalent metal such as sulfuric acid or an organic acid salt such as gallic acid. 5. An aqueous solution of a 1,2-benzisothiazolin-3-one salt with an ethylenediamine or other organic or inorganic alkaline substance and another glycol such as dipropylene glycol, and a trivalent iron salt such as ferric sulfate. A method for producing a deodorant, which comprises mixing an aqueous solution to produce a coprecipitated hybrid fine particle colloid and adjusting the colloid to pH 6-8. 6. The method according to claim 3, wherein a dispersant is added and mixed after the pH is adjusted.