JP2006075703A - Deodorant and deodorizing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a one agent type deodorant which has high dispersion stability and defoaming properties, and can prevent malodors generated from sludge or a dehydrated case in a small amount of chemical for a long time, and to provide a deodorizing method. <P>SOLUTION: The deodorant for sludge or a dewatered cake comprises: a metal salt-based or oxidizer-based odor killer; an organic bacteriostatic agent; a thickener; and a defoamer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a deodorizer and a deodorizing method for sludge or dehydrated cake.

  A large amount of sludge is generated in organic wastewater treatment such as sewage. Such sludge is usually dewatered, and the dewatered cake is finally disposed of by landfill or incineration. Sludge and dewatered cake generated in wastewater treatment decays during storage, producing sulfurous odors such as hydrogen sulfide and methyl mercaptan, which causes a worsening working environment and complaints from neighboring residents. Various deodorizers are used to solve this problem.

Oxidizing-type deodorants such as sodium chlorite and sodium nitrite are effective in extinguishing the odor that has already occurred, but their durability is poor. Metallic deodorants such as zinc chloride are effective in removing hydrogen sulfide, but it is difficult to remove bad odors such as methyl mercaptan and its durability is poor. On the other hand, when a metal-based or oxidizing agent-based deodorant and an organic bacteriostatic agent such as zinc pyrithione are used in combination, sustainability can be improved (Patent Document 1). However, since it is necessary to add two agents separately to the sludge, two tanks and two pumps are required, and there is a problem that the control of the amount of the agent added becomes complicated. A deodorant mixed with a deodorant and an organic bacteriostatic agent is also known (Patent Document 2). Generally, an organic bacteriostatic agent is insoluble in water, so that the organic bacteriostatic agent over time. Since the agent settles, there is a problem that a device such as stirring is necessary so as not to settle. In addition, when a thickener is added to prevent sedimentation, foaming is severe and handling becomes difficult, and when an antifoaming agent is added, dispersion stability deteriorates.
JP 2000-70999 A JP 2003-33797 A

  The present invention provides a deodorizing agent and a deodorizing method that is a single agent type, has high dispersion stability and defoaming performance, and can prevent malodor generated from sludge and dehydrated cake over a long period of time with a small amount of drug. Objective.

In order to solve the above-mentioned problems, the present inventor is a one-component type deodorizing agent that has high dispersion stability and defoaming performance, and can prevent malodor generated from sludge and dehydrated cake over a long period of time with a small amount of drug. And the deodorization method was discovered and it came to make this invention. That is, the present invention is as follows.
1. A deodorizer for sludge or dehydrated cake, comprising a metal salt-based or oxidizing agent-based deodorant, an organic bacteriostatic agent, a thickener and an antifoaming agent.
2. 1. Deodorant is zinc chloride or nitrite Deodorizer according to 1.
3. 1. The organic bacteriostatic agent is a pyrithione compound Or 2. Deodorizer according to 1.
4). 1. Thickener is xanthan gum To 3. Deodorizer according to any one of the above.
5. 1. Antifoam is basic To 4. Deodorizer according to any one of the above.
6.1. To 5. A deodorizing method for a dehydrated cake, comprising adding the deodorizer according to any of the above to sludge and then dehydrating.

  The deodorizing agent and the deodorizing method of the present invention are one-pack type, have high dispersion stability and defoaming performance, and have an effect of preventing a bad odor generated from sludge and dehydrated cake with a small amount of medicine over a long period of time.

The present invention will be specifically described below with a focus on preferred forms thereof.
In the present invention, deodorization refers to a concept including both removal of a malodor that has already occurred and prevention of a malodor that would occur if left untreated.
The target sludge in the present invention is an organic sludge containing an organic substance and the like, and may contain an inorganic substance in addition to the organic substance. Examples of such sludge include sludge generated by treatment of organic wastewater such as sewage, human waste, and industrial wastewater, and include coagulated sediment sludge, primary sediment sludge, activated sludge, surplus sludge, digested sludge, mixed raw sludge, etc. It is. The dehydrated cake which is the object in the present invention is obtained by dehydrating these sludges.

  As the metal salt deodorant in the present invention, a known metal salt deodorant can be used. For example, zinc salt, iron salt, copper salt, nickel salt, molybdenum salt, cobalt salt, silver salt and the like can be mentioned. These metal salt deodorants can be used alone or in combination of two or more if necessary. Such a metal salt is preferably a water-soluble salt. In particular, zinc chloride is preferable because it has high solubility in water, is not colored, and is inexpensive.

As the oxidant deodorant in the present invention, a known oxidant deodorant can be used. For example, hypochlorite, chlorite, nitrite, nitrate, hydrogen peroxide, percarbonate, persulfate, permanganate, iodate, bromate and the like can be mentioned. These oxidant-based deodorants can be used alone or in combination of two or more if necessary. Nitrite is preferred because there is no harmful effect on the incineration of the dehydrated cake and there is little risk of decomposing the thickener coexisting with the deodorizer. Nitrite includes ammonium nitrite, sodium nitrite, potassium nitrite, rubidium nitrite, cesium nitrite, calcium nitrite, strontium nitrite, magnesium nitrite, barium nitrite, nickel nitrite, copper nitrite, silver nitrite, Examples thereof include zinc nitrite and thallium nitrite. These nitrites can be used alone or in combination of two or more. Among these, sodium nitrite and potassium nitrite are less adversely affected by secondary use of the dehydrated cake, and can be particularly preferably used.
The amount of the deodorant in the deodorizer in the present invention is preferably 1 to 80% by mass, more preferably 10 to 50% by mass.

  As the organic bacteriostatic agent in the present invention, a known organic bacteriostatic agent can be used. For example, pyrithione compounds such as zinc pyrithione, aluminum pyrithione, iron pyrithione, sodium pyrithione, 2,2′-dithiobis-pyridine-1,1′-dioxide, 1,2-benzoisothiazolin-3-one and 5-chloro-2- Thiazoline compounds such as methylisothiazoline-3-one, 2-n-octyl-4-isothiazolin-3-one, 3,5-dimethyltetrahydro-1,3,5-thiadiazine-2-thione and 3,3′-ethylene Thiadiazine compounds such as bis (tetrahydro-4,6-dimethyl-1,3,5-thiadiazine-2-thione), cyanate compounds such as methylthiocyanate and methylenebisthiocyanate, ethylenebis (dithiocarbamate) zinc, ethylenebis (dithiocarbamine) Acid) carbamic acid such as manganese, zinc dimethyldithiocarbamate Compound, bis (dimethylthiocarbamoyl) disulfide, p-chloro-m-cresol, diisopropyl-1,3-dithiolane-2-ylidenemalonate, 5,5'-dichloro-2,2'-dihydroxydiphenylmethane 4,5-dichloro-1,2-dithiolane-3-one, dichlorophen, 2,3-dichloro-1,4-naphthoquinone, 2,5-dichloro-4-bromophenol, 5,6-dihydro-2 -Methyl-1,4-oxatin-3-carboxanilide-4,4'-dioxide, 1,2-dibromo-2,4-dicyanobutane, 2,3,3-triiodo alcohol, N- (fluorodichloromethylthio) Examples include phthalimide, 4-bromo-3-ethoxycarbonyloxy-1,2-diiodo-1-propene, and α-bromocinnamaldehyde. These organic bacteriostatic agents may be used alone or in combination of two or more. In particular, zinc pyrithione and 2,2′-dithiobis-pyridine-1,1′-dioxide are preferable because they are effective in a smaller amount and do not contain coloring components, and 1,2-benzoisothiazoline-3- A combined use of ON is also preferable.

  The amount of the organic bacteriostatic agent in the deodorizer in the present invention is preferably 0.1 to 30% by mass, more preferably 0.5 to 10% by mass. Since an organic bacteriostatic agent is generally often insoluble or hardly soluble in water, it is preferably dispersed in a deodorizing agent using a dispersant. In this case, the average particle size of the organic bacteriostatic agent is preferably less than 20 μm, and more preferably less than 5 μm. The dispersant is preferably nonionic or anionic or a mixture thereof. Suitable nonionic dispersants include ethylene oxide or propylene oxide condensates and block copolymers thereof. Suitable anionic dispersants include sodium lignin sulfonate and polynaphthalene sulfonate sodium salt. A suitable amount of the dispersant is 3 to 30% by mass with respect to the organic bacteriostatic agent.

  Examples of the thickener in the present invention include xanthan gum, guar gum, pectin, carboxymethyl cellulose, polyvinyl alcohol and the like. In particular, xanthan gum is preferable because of its high stability in the presence of a deodorant and high dispersion stabilizing ability of the organic bacteriostatic agent. The blending amount of the thickener with respect to the deodorizer is preferably 0.01 to 5% by mass, more preferably 0.05 to 1% by mass.

  Examples of antifoaming agents in the present invention include silicone emulsions, silica silicones, silicone compounds, mineral oils, vegetable oils, metal soaps, polyethers, higher alcohol emulsions, amides, and mixtures thereof. Can be mentioned. These antifoaming agents can be classified into basic, neutral, and acidic from the pH indicated by the 1% by mass aqueous solution, but they have little adverse effect on the dispersion stability of the organic bacteriostatic agent and have a high antifoaming effect. Therefore, a basic antifoaming agent is preferable. The blending amount of the antifoaming agent with respect to the deodorizer is preferably 0.01 to 5% by mass, more preferably 0.05 to 1% by mass.

In the deodorizer of the present invention, a metal salt-based or oxidizer-based deodorant, an organic bacteriostatic agent, a thickener and an antifoaming agent are essential components. , Masking agents, colorants, pH adjusting agents, and the like.
The deodorizer can be added to the sludge or dehydrated cake, but it is preferable to add the deodorizer to the sludge not only when the sludge is expected to deodorize but also when only the deodorized cake is expected to be deodorized. The sludge to be added is preferably a concentrated sludge in which primary sludge or excess sludge is concentrated. In addition, the location where the concentrated sludge is transferred is preferably a place where the concentrated sludge is transferred, or a sludge storage tank that stores the transferred concentrated sludge before dehydration.

  Since the deodorizer of the present invention is excellent in the immediate effect and sustainability of the deodorizing effect, only one agent exhibits a sufficient deodorizing effect. However, if necessary, the above-described metal salt-based or oxidizing agent-based deodorant It is also possible to use in combination with one or more deodorizers selected from the agents or one or more organic bacteriostatic agents selected from the aforementioned organic bacteriostatic agents.

  The amount of addition of the deodorizer of the invention to sludge varies depending on the concentration of malodor already generated in the sludge, the concentration of organic matter in the sludge, the time required for deodorization, etc. 10-10000 mg is preferable and 100-1000 mg is more preferable. When the amount is 10 mg or more with respect to 1 liter of sludge, the deodorizing effect can be continuously expressed. When the amount is 10,000 mg or less, the running cost is suppressed and the economy is excellent. In order to add a deodorizing agent, it can be supplied using a diaphragm-type or plunger-type metering pump and added to sludge or dehydrated cake. In order to make the addition amount of the deodorizing agent per sludge uniform, the metering pump is preferably interlocked with a pump for transferring sludge. The sludge dewatering means is not particularly limited. Usually, the sludge is concentrated from a concentrator such as a gravity concentrator or a centrifugal concentrator to be concentrated sludge, and after adding a flocculant, a belt press machine, a filter press machine, It is dehydrated by a dehydrator such as a screw press machine to form a dewatering cake. As the flocculant, for example, a polymer of dimethylaminoethyl acrylate quaternary salt, a polymer of dimethylaminoethyl methacrylate quaternary salt, a copolymer of these quaternary salts and acrylamide, polyamidine, or the like can be used. .

The present invention will be described based on examples.
[Example 1]
(1) Preparation of deodorant: After adding 0.09 part by mass of xanthan gum and 0.2 part by mass of antifoaming agent A (mainly silica and polyether) to 9 parts by mass of water, the particle size is 3 μm or less. 9 parts by mass of a dispersion of 50% by mass of zinc pyrithione powder dispersed in water with 1% by mass of sodium polynaphthalene sulfonate and 100 parts by mass of a deodorant dispersed uniformly by adding 82 parts by mass of a 48% by mass zinc chloride aqueous solution Got.
(2) pH measurement of antifoaming agent: An aqueous solution in which 1% by mass of antifoaming agent A was dissolved was prepared, and the pH was measured.
(3) Measurement of dispersion stability: The deodorizer prepared above was placed in a 100 mL graduated cylinder and allowed to stand at room temperature for 21 days. The height of the settled interface was read and used as the sedimentation rate.
(4) Measurement of defoaming performance: 100 mL of the deodorant prepared above was placed in a 200 mL graduated cylinder, and air was bubbled through a bubbler installed at the bottom by adding 100 mL / min. The foam height after foaming for 10 minutes was read as the defoaming performance.

(5) Measurement of deodorization performance: Add 80 mg of deodorizer prepared above (400 mg / L to sludge) to a 500 mL Erlenmeyer flask containing SS concentration 3.3%, pH 5.7 sewage mixed sludge 200 mL. Stir for 10 seconds. After standing at 25 ° C. for 16 hours, the gas concentration in the Erlenmeyer flask was measured with a detector tube described later. Thereafter, a cationic polymer flocculant (C-68P: manufactured by Asahi Kasei Clean Chemical Co., Ltd., trademark) was added to carry out a flocculation treatment. The agglomerated sludge was filtered with a resin filter cloth and then pressed with a press at a pressure of 9.8 kPa for 2 minutes to obtain a dehydrated cake. This dehydrated cake was sealed in a resin bag together with 20 mL of air per 1 g of wet mass, stored in a thermostatic bath at 25 ° C., and the gas concentration in the bag was measured with a detector tube described later at regular intervals. In addition, the following model numbers of gas detector tubes (manufactured by Gastec Co., Ltd.) were used for gas concentration measurement: hydrogen sulfide 4LL, methyl mercaptan 71.
The results are shown in Tables 1 and 2.

[Examples 2 to 6]
It carried out like Example 1 except having used antifoamer BF instead of antifoamer A. FIG. The results are shown in Table 1.

[Comparative Example 1]
A deodorant was prepared in the same manner as in Example 1 except that xanthan gum and antifoam A were not used. The results are shown in Table 1.

[Comparative Example 2]
A deodorant was prepared in the same manner as in Example 1 except that the antifoam A was not used. The results are shown in Table 1.

[Example 7]
(1) Preparation of deodorant: After adding 0.2 parts by mass of xanthan gum and 0.4 parts by mass of antifoam A to 40 parts by mass of water, 2,2′-dithiobis-pyridine-1 having a particle size of 3 μm or less , 1'-dioxide powder 10% by weight dispersion of sodium polynaphthalene sulfonate 0.2% by weight in water 20 parts by weight, and sodium nitrite 40 parts by weight added uniformly deodorant 100 parts by mass were obtained.
(2) to (5) Various measurements: performed in the same manner as in Example 1.
The results are shown in Tables 1 and 2.

[Comparative Example 3]
Deodorizing performance was evaluated in the same manner as in Example 1 except that no deodorizing agent was used. The results are shown in Table 2.

  From the results in Table 1, it can be seen that the deodorizer of the present invention is excellent in dispersion stability and antifoaming performance. Moreover, it turns out that it is especially excellent when the basic defoamers A and B are used.

  From the results shown in Table 2, the deodorizer of the present invention was added in a small amount of 400 mg / L, and compared with the case where no deodorizer was added, hydrogen sulfide and methyl mercaptan, which are malodors generated from sludge and dewatered cake. It can be seen that the concentration can be significantly reduced, and in particular, the generation of malodor from the dewatered cake can be prevented for 2 days or more.

  The deodorizing agent and the deodorizing method of the present invention can be suitably used in the field of organic wastewater treatment.

Claims (6)

  A deodorizer for sludge or dehydrated cake, comprising a metal salt-based or oxidizing agent-based deodorant, an organic bacteriostatic agent, a thickener and an antifoaming agent.   The deodorizer according to claim 1, wherein the deodorizer is zinc chloride or nitrite.   The deodorizer according to claim 1 or 2, wherein the organic bacteriostatic agent is a pyrithione compound.   The deodorizer according to any one of claims 1 to 3, wherein the thickener is xanthan gum.   The deodorizer according to any one of claims 1 to 4, wherein the defoamer is basic.   A method for deodorizing sludge or dehydrated cake, wherein the deodorizer according to any one of claims 1 to 5 is added to sludge and then dehydrated.