JP6205242B2 - Odor control method for odor generating substance and odor control composition - Google Patents

Description

  The present invention relates to an odor control method for odor generating substances and an odor control composition. More specifically, the present invention can suppress, for a long period of time, odors derived from hydrogen sulfide, methyl mercaptan, etc. generated by microbial activity from dewatered cakes of sewage treatment plants, etc., and has relatively low toxicity. Further, the present invention relates to an odor suppression method and an odor suppression composition for an inexpensive odor generating substance.

  After concentrating sludge generated at sewage treatment plants as a method to control odors originating from hydrogen sulfide and methyl mercaptan generated from dehydrated cakes at sewage treatment plants, human waste treatment plants, food factories, paper pulp factories, etc. In addition, a deodorizing (odor suppression) method has been proposed in which an oxidizing agent excluding peroxide and a predetermined amount of nitrite are added to the concentrated sludge slurry and further dehydrated by a dehydrator (for example, a patent) Reference 1).

Japanese Patent No. 3674939

  The deodorizing method of the dehydrated cake described in Patent Document 1 described above effectively uses nitrite having a high deodorizing ability as a deodorizing means in the entire sewage treatment process including the dehydrated cake stored in an open system. Although it exhibits a certain deodorizing effect, it has a problem of relatively high toxicity, such as nitrite remaining as an environmental problem and a causative substance of a carcinogenic substance.

  The present invention has been made in view of the above-mentioned problems, and is capable of suppressing odors derived from hydrogen sulfide, methyl mercaptan and the like produced by the activity of microorganisms over a long period of time, has relatively low toxicity, and An object is to provide an odor control method and an odor control composition for an inexpensive odor generating substance.

As a result of intensive studies to achieve the above object, the present inventors have obtained nitric acid or nitrate, imidazole or a salt thereof, and tetrakis, which have a large industrial production and can be obtained at low cost and have lower environmental toxicity than nitrite. at least one bets selected from the group consisting of (hydroxymethyl) phosphonium salts, inhibit by adding the odor substance, the odor derived from the odor of hydrogen sulfide and methyl mercaptan is produced from a material such as a long period of time The present invention has been completed. That is, according to the present invention, the following odor control method and odor control composition for odor generating substances are provided.

[1] An odor suppressing method for an odor generating substance for suppressing odor generated from an odor generating substance, wherein nitric acid or a salt thereof ( first additive substance) is added to the odor generating substance in the odor generating substance. with the concentration of the first additive material is added in an amount of 50 to 1000 mg / L as nitrate ion concentration, the odor substance, selected from the imidazole or the group consisting of a salt,及 beauty tetrakis (hydroxymethyl) phosphonium salt at least one (second additive substance), odor before Symbol odor substances, characterized in that the concentration of the second additive material in odor substance is added in an amount of 5 to 300 mg / L to Suppression method.

[2] The method for suppressing odor of an odor generating substance according to [1], wherein the odor generating substance is any one of the following (1) to (4) in a sewage treatment plant.
(1) Sludge generated in the first sedimentation basin and its concentrate (2) Sludge generated in the final sedimentation basin and its concentrate (3) Mixture of (1) and (2) (4) Dehydrated cake

[3] The odor control method for odor generating substances according to [1] or [2], wherein the odor generated from the odor generating substance is an odor derived from hydrogen sulfide or methyl mercaptan.

[4] The odor generating substance according to any one of [1] to [3], wherein the first additive substance and the second additive substance are simultaneously added to the odor generating substance. Odor control method.

[5] as an active ingredient for suppressing odor generated from the odor-generating substance, selected and nitric acid or a salt thereof (first additive substance), imidazole or a salt thereof, from 及 beauty tetrakis group consisting of (hydroxymethyl) phosphonium salt in at least one (second additive substance) containing an amount concentration of said first additive material before Symbol odor substance is 50 to 1000 mg / L as nitrate ion concentration, also, the An odor-suppressing composition, which is added to the odor-generating substance in an amount such that the concentration of the second additive substance in the odor-generating substance is 5 to 300 mg / L and is used for suppressing the odor.

[6] The odor-suppressing composition according to [5], wherein the odor generating substance is any of the following (1) to (4) in a sewage treatment plant.
(1) Sludge generated in the first sedimentation basin and its concentrate (2) Sludge generated in the final sedimentation basin and its concentrate (3) Mixture of (1) and (2) (4) Dehydrated cake

[7] The odor control composition according to [5] or [6], wherein the odor generated from the odor generating substance is an odor derived from hydrogen sulfide or methyl mercaptan.

  According to the present invention, it is possible to suppress the odor derived from hydrogen sulfide, methyl mercaptan, etc. generated by the activity of microorganisms over a long period of time, and the odor control method and odor control of an odor-generating substance that is relatively low in toxicity and inexpensive. Compositions are provided.

1. The odor control method of the odor generating material of the present embodiment is an odor control method of the odor generating material that suppresses the odor generated from the odor generating material. salts (first additive material; hereinafter sometimes referred to as nitrate-based material), and imidazole or a salt thereof, at least one selected from 及 beauty tetrakis group consisting of (hydroxymethyl) phosphonium salts (hereinafter second additive The nitrate substance and the second additive substance may be such that the concentration of the nitrate substance in the odor generating substance is 50 to 1000 mg / L as a nitrate ion concentration. And adding to the odor generating substance such that the concentration of the second additive substance in the odor generating substance is 5 to 300 mg / L. Is. Hereinafter, each component will be described.

(1-1: Odor generating substance)
Below, the odor generating substance to which the present invention is applied will be described using an example of a sewage treatment process. The raw sewage to be treated is separated in the first settling basin as the first settled sludge and then concentrated in the sludge concentration tank (the first settled sludge and concentrate here become odor generating substances). The supernatant water of the first sedimentation basin is sent to an aeration tank after adding a flocculant as necessary, and microbial treatment is performed by an activated sludge method. The treated water in the aeration tank is added with a flocculant as necessary, separated as sludge in the final sedimentation basin, and then concentrated in the sludge concentration tank (the sludge and concentrate here become odor generating substances. ). Separated sludge and sludge concentrated in the sludge concentration tank are separated from those generated in the first sedimentation basin and those generated in the final sedimentation basin (as described above, sludge in the first sedimentation basin and final sedimentation basin). And the concentrate becomes an odor generating substance) or a mixture thereof (this mixture becomes an odor generating substance), is sent to a sludge storage tank, dehydrated by a dehydrator, and dehydrated cake (this dehydrated cake becomes an odor generating substance) ).

That is, examples of the odor generating material to which the present invention is applied include any of the following (1) to (4) generated in a treatment process of a sewage treatment plant.
(1) Sludge generated in the first sedimentation basin and its concentrate (2) Sludge generated in the final sedimentation basin and its concentrate (3) Mixture of (1) and (2) (4) Dehydrated cake

(1-2: Odor)
Examples of the odor generated from the above-mentioned odor generating substance include hydrogen sulfide or methyl mercaptan-derived odor generated by the activity of microorganisms. Since these odors greatly affect the environment and human life, it is necessary to suppress the odors. In particular, since dehydrated cake is often transported and stored in an open system, it is important to suppress its odor.

(1-3: Additive substance)
In the odor control method of the odor generating substance of the present embodiment, the substance added to the odor generating substance used for suppressing the odor generated from the odor generating substance is nitric acid or a salt thereof (nitric substance), and imidazole or a salt thereof, a 及 beauty tetrakis least one member selected from the group consisting of (hydroxymethyl) phosphonium salt (second additive material).

As described above, the mechanism by which the combination of the nitric acid-based substance and the second additive substance is effective in suppressing the odor generated from the odor generating substance is not necessarily clear, but the nitric acid added to the odor generating substance is not necessarily known. The substance is reduced from nitric acid to nitrous acid by the "nitrate reduction" action of nitrate reducing bacteria, and the odor of nitrous acid is suppressed (deodorized), for example, to suppress odors derived from hydrogen sulfide or methyl mercaptan. In addition, the progress of the "denitrification" action of nitrite-reducing bacteria to the next stage, that is, the progress of the reduction reaction from nitrous acid to nitrogen is moderately suppressed by the second additive substance, and odor suppression is prolonged. Presumed to be maintained.

(1-3-1: nitrate material)
Among nitric acid-based substances, nitric acid can be suitably used, for example, which can be obtained at low cost as a waste acid, but is not particularly limited. Examples of the nitrate include sodium nitrate, calcium nitrate, aluminum nitrate, ferrous nitrate, ferric nitrate, ammonium nitrate, zinc nitrate, and guanidinium nitrate. Of these, sodium nitrate and calcium nitrate are preferable.

There is no restriction | limiting in particular as addition time, For example, you may add simultaneously with the 2nd additive substance mentioned later, and may add separately. Among them, it is preferable from the viewpoint of labor for addition to add simultaneously with the second additive substance described later.

  The added amount is usually added to the odor generating substance so that the concentration of the nitric acid-based substance in the odor generating substance is 50 to 1000 mg / L as the nitrate ion concentration, and is 100 to 500 mg / L as the nitrate ion concentration. It is preferable to add so that it becomes. If it exceeds 1000 mg / L, the cost becomes too high, and if it is less than 50 mg / L, a sufficient effect of suppressing odor generation cannot be obtained.

  Although there is no restriction | limiting in particular as an addition method, For example, adding using a pump as aqueous solution can be mentioned.

(1-3-2: second additive substance)
The second additive material, as described above, an imidazole or a salt thereof, but is at least one selected from 及 beauty tetrakis group consisting of (hydroxymethyl) phosphonium salt, specifically, as a salt of imidazole, e.g. imidazole hydrochloride, imidazole sulfates, can be mentioned imidazole phosphate salts as the salt of Te tetrakis (hydroxymethyl) phosphonium, for example, tetrakis (hydroxymethyl) phosphonium sulfates, tetrakis chloride (hydroxymethyl) phosphonium A chloride etc. can be mentioned. Of these, hydrochloride is preferable.

  There is no restriction | limiting in particular as an addition time, You may add simultaneously with the above-mentioned nitric acid-type substance, and may add separately. Among these, a mixed aqueous solution with a nitric acid-based material is preferable from the viewpoint of ease of addition.

The addition amount is added to the odor generating substance so that the concentration of the second additive substance in the odor generating substance is usually 5 to 300 mg / L, and is added to 7.5 to 200 mg / L. It is preferred that If it exceeds 300 mg / L, the cost becomes too high, and if it is less than 5 mg / L, a sufficient effect of suppressing odor generation cannot be obtained.

  Although there is no restriction | limiting in particular as an addition method, For example, adding using a pump as mixed aqueous solution with a nitric acid-type substance can be mentioned.

2. Odor suppressing composition The odor suppressing composition of the present embodiment is an odor suppressing composition that is added to an odor generating substance to suppress odor generated from the odor generating substance, and is nitric acid or a salt thereof. containing a (hereinafter, sometimes referred to nitric acid-based material), Lee imidazole or a salt thereof, and a 及 beauty tetrakis least one member selected from (hydroxymethyl) phosphonium salt or Ranaru group (second additive material). The odor control composition, the concentration of the nitrate-based material in the odor substance is, in an amount containing 50 to 1000 mg / L as nitrate ion concentration, also, the second additive material in the odor substance concentration is in an amount of 5 to 300 mg / L, and is used to suppress the odor is added to the odor substances.

The odor generating substance and odor used in the odor suppressing composition of the present embodiment, and the nitric acid-based substance and the second additive substance constituting the odor suppressing composition of the present embodiment include the odor generating substance described above. The thing similar to what is used by the odor control method of can be used.

Nitric acid substance is the concentration of the nitrate-based material in the odor substance, usually contained in odor substance in such a way that 50 to 1000 mg / L as nitrate ion concentration, 100 to 500 mg as a nitrate ion concentration / It is preferable to contain so that it may become L. If it exceeds 1000 mg / L, the cost becomes too high, and if it is less than 50 mg / L, a sufficient effect of suppressing odor generation cannot be obtained.

The second additive substance, the concentration of the second additive material in odor substance, usually, such that 5 to 300 mg / L, is contained in the odor substance, 7.5～200Mg / It is preferable to contain so that it may become L. If it exceeds 300 mg / L, the cost becomes too high, and if it is less than 5 mg / L, a sufficient effect of suppressing odor generation cannot be obtained.

  There are no particular restrictions on the method of inclusion, but examples include an aqueous solution.

In addition to the nitric acid-based substance and the second additive substance described above, for example, an acidic substance may be included in the odor-suppressing composition of the present embodiment from the viewpoint of the storage stability of the second additive substance. it can.

  Below, the odor control method and odor control composition of the odor generating substance of the present invention will be described more specifically using examples. Note that the present invention is not limited in any way by the following examples.

Example 1
Mixing the same amount of initial sludge pond sludge (SS concentration = 12,000 mg / L) and excess sludge (SS = 10,000 mg / L) collected from a sewage treatment plant in a polypropylene container with a capacity of 500 mL After adding 200 mL of sludge, as the nitrate substance, sodium nitrate (hereinafter sometimes referred to as Na nitrate) is added to a concentration of 300 mg / L, and imidazole is added as the second additive. They were simultaneously added at a time so as to be 50 mg / L, sealed and allowed to stand at 20 ° C. After 24 or 48 hours, the container was opened, and immediately, the concentration of hydrogen sulfide in the gas phase in the container was measured using a detector tube manufactured by Gastec. The results are shown in Table 1.

  In Table 1, THPS represents tetrakis (hydroxymethyl) phosphonium sulfate.

(Example 4,5,8,9,12)
The same procedure as in Example 1 was performed except that the addition concentration of the nitric acid-based substance and the type and addition concentration of the second addition substance were changed to those shown in Table 1. The results of measuring the hydrogen sulfide concentration are shown in Table 1.

(Comparative example 1 , 2 , 5-8 )
The same procedure as in Example 1 was performed except that the addition concentration of the nitric acid-based substance and the type and addition concentration of the second addition substance were changed to those shown in Table 1. The results of measuring the hydrogen sulfide concentration are shown in Table 1.

From the measurement results shown in Table 1, the following can be understood. That is, when the concentration of Na nitrate in Examples 1 and 4 is 300 mg / L, in the case of containing only Na nitrate without containing the second additive substance (Comparative Example 6), within a short period of 24 hours. Hydrogen sulfide was generated. In contrast, imidazole Example 1 and 4, the addition of T HPS it is seen that the generation of hydrogen sulfide over a long period of more than 48 hours was suppressed completely. However, when neither the nitric acid-based material of Comparative Example 1 nor the second additive material is contained, when Comparative Example 2 and 5 containing only the second additive material without containing Na nitrate, Comparative Example 7 No significant suppression of hydrogen sulfide generation was observed when either Na nitrate 8 or 8 or the second additive was less than the specified amount. Further, in Examples 5 , 8, 9, and 12, in which either the corresponding sodium nitrate concentration or the second additive substance concentration is low compared to Examples 1 and 4, generation of hydrogen sulfide was observed after 48 hours. However, the generation of hydrogen sulfide was not observed in 24 hours, and was remarkable as compared with Comparative Examples 1 , 2 , 5-8 (when the concentration of Na nitrate or / and the second additive substance was less than the specified amount). It can be seen that the generation of hydrogen sulfide is suppressed.

  INDUSTRIAL APPLICABILITY The present invention is effectively used for the treatment of industrial wastewater containing organic substances such as sewage treatment plants, human waste treatment plants, food factories and paper pulp factories.

Claims (7)

An odor control method for an odor generating substance that suppresses an odor generated from the odor generating substance,
The odor substance, nitric acid or a salt thereof (first additive substance), with the concentration of the first additive material in the odor substance is added in an amount of 50 to 1000 mg / L as nitrate ion concentration ,
The odor substances, imidazole or a salt thereof, at least one selected from 及 beauty tetrakis group consisting of (hydroxymethyl) phosphonium salt (second additive material), the second additive before Symbol odor substance An odor control method for an odor-generating substance, wherein the substance is added in an amount such that the concentration of the substance is 5 to 300 mg / L. The method for suppressing odor of an odor generating substance according to claim 1, wherein the odor generating substance is any of the following (1) to (4) in a sewage treatment plant.
(1) Sludge generated in the first sedimentation basin and its concentrate (2) Sludge generated in the final sedimentation basin and its concentrate (3) Mixture of (1) and (2) (4) Dehydrated cake   The odor generation method according to claim 1 or 2, wherein the odor generated from the odor generating substance is an odor derived from hydrogen sulfide or methyl mercaptan. The odor control method for an odor generating substance according to any one of claims 1 to 3, wherein the first additive substance and the second additive substance are simultaneously added to the odor generating substance simultaneously. As an active ingredient for suppressing odor generated from the odor-generating substance, at least a nitric acid or a salt thereof (first additive substance), imidazole or a salt thereof, selected from 及 beauty tetrakis group consisting of (hydroxymethyl) phosphonium salt 1 One contains the (second additive substance) and,
In an amount concentration of said first additive material before Symbol odor substance is 50 to 1000 mg / L as nitrate ion concentration, The concentration of the second additive material in the odor substance is 5 ~ An odor-suppressing composition which is added to the odor-generating substance in an amount of 300 mg / L and used for suppressing the odor. The odor-suppressing composition according to claim 5, wherein the odor-generating substance is any one of the following (1) to (4) in a sewage treatment plant.
(1) Sludge generated in the first sedimentation basin and its concentrate (2) Sludge generated in the final sedimentation basin and its concentrate (3) Mixture of (1) and (2) (4) Dehydrated cake   The odor suppressing composition according to claim 5 or 6, wherein the odor generated from the odor generating substance is an odor derived from hydrogen sulfide or methyl mercaptan.