JP2022175164A - Organic sludge dehydrating agent - Google Patents

Abstract

To provide a sludge dehydrating agent to be used for sludge dehydration treatment, having a deodorant function and higher in performance, and a sludge dehydration method.SOLUTION: A sludge dehydrating agent can deodorize or diminish a sulfur-based odor such as hydrogen sulfide or methyl mercaptan that causes a foul smell and achieve improvement in sludge dehydrating performance by using the sludge dehydrating agent containing water-soluble polymer having a specified composition and isothiazoline compound. It is preferable that a content ratio of the isothiazoline compound to the water-soluble polymer be 0.005-0.1 mass% in a sludge dehydrating agent product.SELECTED DRAWING: None

Description

The present invention relates to a water-soluble polymer that is widely used as a sludge dewatering agent, and more specifically, a sludge dewatering agent containing a water-soluble polymer that has a deodorizing effect and improves sludge dewatering performance, and a sludge dewatering agent that uses the same. The present invention relates to a sludge dewatering method.

Sludge for dehydration treatment of organic sludge such as pre-settled sludge from sewage, surplus sludge or mixed raw sludge from effluent from activated sludge tank, digested sludge obtained by anaerobic digestion of these sludges, or livestock sludge. A water-soluble polymer is used as a dehydrating agent.
Polyacrylamide (PAM)-based water-soluble polymer is widely used as a general sludge dehydrating agent, and the sludge added with the sludge dehydrating agent is dewatered by a suitable dehydrator such as a belt press or a screw press and processed as a dehydrated cake. be.
These sludge and dehydrated cake generate a sulfur-based odor caused by hydrogen sulfide, methyl mercaptan, and the like, which may pose a problem by deteriorating the working and living environments in the sludge dehydration process and subsequent treatment processes. Accordingly, application of various compounds as deodorants for sludge or dehydrated cake has been devised.
For example, Patent Document 1 discloses a deodorant for dehydrated cake using a 1,2-benzisothiazolin-3-one salt. Patent Document 2 discloses a deodorant for sludge or dehydrated cake containing 1,2-benzisothiazolin-3-one and a pyrithione compound.
Also disclosed is a method for preventing the generation of odor using a deodorant and a polymer flocculant in the sludge dehydration process. Patent Document 3 discloses a method for preventing odor generation by adding a polymer flocculant after adding a metal salt of 2-mercaptobenzimidazole or a divalent metal salt of 2-mercaptobenzothiazole to sludge.
Furthermore, a sludge dewatering agent containing a deodorant and a polymer flocculant is disclosed.
Patent Document 4 discloses an emulsified PAM-based polymer sludge dewatering agent containing terpenes such as menthol and essential oils such as peppermint oil and eucalyptus oil as deodorants. Patent Document 5 discloses a polymer flocculant having a deodorizing function by mixing a PAM-based polymer flocculant with humus soil to which p-dichlorobenzene or vegetable essential oil is adsorbed.
However, there are cases where a satisfactory deodorizing effect cannot be obtained even with these, or a large addition rate is required to obtain a deodorizing effect or a dehydrating effect. Therefore, there is a demand for a more efficient sludge dehydrating agent having deodorant and dehydrating effects.

JP-A-6-134492 JP 2006-75704 A JP-A-2005-763 JP-A-59-173110 JP-A-59-112811

The present invention relates to a sludge dehydrating agent used for sludge dewatering treatment, and an object of the present invention is to provide a sludge dehydrating agent and a sludge dehydrating method that have deodorant action and higher performance.

As a result of intensive studies to solve the above problems, the use of a sludge dehydrating agent containing a water-soluble polymer with a specific composition and an isothiazoline compound has a deodorizing effect and achieves improved sludge dewatering performance. The inventors have found that it is possible to achieve the present invention.

By using the sludge dehydrating agent of the present invention, it is possible to deodorize or deodorize sulfur-based odors such as hydrogen sulfide and methyl mercaptan, which cause bad odors, for organic sludge, which is a problem due to the generation of bad odors. and improve sludge dewatering performance.

一般式（１）
Ｒ_１は水素又はメチル基、Ｒ_２、Ｒ_３は炭素数１～３のアルキルあるいはアルコキシ基、Ｒ_４は炭素数１～３のアルキルあるいはアルコキシ基、７～２０のアルキル基あるいはアリール基、Ａは酸素またはＮＨ、Ｂは炭素数２～４のアルキレン基を表わす、Ｘ_１ ^－は陰イオンをそれぞれ表わす。

一般式（２）
Ｒ_５は水素、メチル基またはカルボキシメチル基、ＱはＳＯ_３ ^－、Ｃ_６Ｈ_４ＳＯ_３ ^－、ＣＯＮＨＣ（ＣＨ_３）_２ＣＨ_２ＳＯ_３ ^－、Ｃ_６Ｈ_４ＣＯＯ^－あるいはＣＯＯ^－、Ｒ_６は水素またはＣＯＯＹ_２、Ｙ_１あるいはＹ_２は水素または陽イオンをそれぞれ表わす。 As the water-soluble polymer in the present invention, 1 to 99 mol% of a cationic monomer represented by the following general formula (1) and 0 to 99 mol of an anionic monomer represented by the following general formula (2) % and 1 to 99 mol % of nonionic monomers as structural units.
The cationic monomer represented by formula (1) is preferably 20 to 99 mol %, more preferably 30 to 99 mol %, and even more preferably 40 to 99 mol %. This is because medium to high molar proportions of cationic monomers are more versatile for sludge species. When the anionic monomer represented by the general formula (2) is contained, the content of the anionic monomer is preferably 1 to 20 mol%, more preferably 1 to 15 mol%.

General formula (1)
_{A _ _ _} represents oxygen or NH, B represents an alkylene group having 2 to 4 carbon atoms, and X ₁ ^- represents an anion.

general formula (2)
R ₅ is hydrogen, a methyl group or a carboxymethyl group, Q is SO ₃ ⁻ , C ₆ H ₄ SO ₃ ⁻ , CONHC(CH ₃ ) ₂ CH ₂ SO ₃ ⁻ , C ₆ H ₄ COO ⁻ or COO ⁻ , R ₆ represents hydrogen or COOY ₂ , Y ₁ or Y ₂ represents hydrogen or a cation, respectively.

The cationic monomer represented by the general formula (1) is a quaternized product of dimethylaminoethyl (meth)acrylate or dimethylaminopropylacrylamide with a halide of a lower alkyl group such as methyl chloride or ethyl chloride. For example, (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth)acryloylaminopropyltrimethylammonium chloride, (meth)acryloylaminopropyldimethylbenzylammonium chloride, (meth) ) acryloyloxy-2-hydroxypropyltrimethylammonium chloride and the like. Two or more of these may be used in combination. Examples of the anionic monomer represented by the general formula (2) include (meth)acrylic acid or its alkali metal salt or ammonium salt such as sodium salt, maleic acid or its alkali metal salt, acrylamido-2-methylpropanesulfone. acrylamidoalkanesulfonic acids such as acids, alkali metal salts or ammonium salts thereof, and the like. Two or more of these may be used in combination.

Nonionic monomers used in the present invention include (meth)acrylamide, N,N'-dimethylacrylamide, acrylonitrile, (meth)acrylate-2-hydroxyethyl, diacetoneacrylamide, N-vinylpyrrolidone, N -vinylformamide, N-vinylacetamide, acryloylmorpholine and the like. Among these, (meth)acrylamide is preferred. Two or more of these may be used in combination.

A water-soluble polymer in the present invention can be produced by a known method. It can be produced by copolymerizing one or more monomers or a mixture of monomers selected from cationic monomers, nonionic monomers and anionic monomers. Copolymerization is carried out by any polymerization method. For example, after polymerization by aqueous solution polymerization, water-in-oil emulsion polymerization, water-in-oil dispersion polymerization, salt-water dispersion polymerization, etc., it can be used in any desired product form, such as an aqueous solution, salt-water dispersion, water-in-oil emulsion, or powder. can do. Among these, the water-in-oil emulsion polymerization is preferable because the molecular weight and polymer structure can be easily adjusted.

In the case of a water-in-oil emulsion, it can be produced appropriately according to the methods described in JP-A-10-140496, JP-A-2011-99076, and the like. That is, a monomer mixture containing one or more selected from cationic monomers, nonionic monomers, and anionic monomers is combined with water, and an oily substance composed of at least a water-immiscible hydrocarbon. , an amount effective to form a water-in-oil emulsion and at least one surfactant having an HLB are mixed, vigorously stirred to form a water-in-oil emulsion, and then polymerized.

Examples of oily substances composed of hydrocarbons used as dispersion media include paraffins, naphthenes, mineral oils such as kerosene, light oil, medium oil, etc., or properties such as boiling point and viscosity in substantially the same range as these. and a hydrocarbon-based synthetic oil, or a mixture thereof. The content is in the range of 20% by mass to 50% by mass, preferably in the range of 20% by mass to 35% by mass, based on the total weight of the water-in-oil emulsion.

Examples of the at least one surfactant having an effective amount and HLB to form a water-in-oil emulsion are nonionic surfactants with an HLB of 1 to 15, specific examples of which include sorbitan monooleate, Sorbitan monostearate, sorbitan monopalmitate, polyoxyethylene nonylphenyl ether and the like. The amount of these surfactants to be added is 0.5 to 10% by mass, preferably 1 to 5% by mass, based on the total amount of the water-in-oil emulsion.

The polymerization concentration of the monomer is in the range of 20 to 60% by mass, and the polymerization concentration and temperature are appropriately set according to the composition of the monomer and the selection of the initiator. The polymerization temperature is 20 to 80°C, preferably 20 to 60°C. A radical polymerization initiator is used for polymerization initiation. These initiators may be either oil-soluble or water-soluble, and can polymerize any of azo, redox, and peroxide initiators. Examples of oil-soluble azo initiators include 2,2'-azobisisobutyronitrile, dimethyl-2,2'-azobisisobutyrate, and 1,1'-azobis(cyclohexane-1-carbonitrile). , 2,2′-azobis(2-methylbutyronitrile), dimethyl-2,2′-azobis(2-methylpropionate), 2,2′-azobis(4-methoxy-2,4-dimethylvalero nitrile) and the like.

Examples of water-soluble azo initiators include 2,2′-azobis(amidinopropane) dihydrochloride, 2,2′-azobis[2-(5-methyl-imidazolin-2-yl)propane] dichloride hydride, 4,4'-azobis(4-cyanovaleric acid) and the like. Examples of redox systems include combinations of ammonium peroxodisulfate with sodium sulfite, sodium hydrogen sulfite, trimethylamine, tetramethylethylenediamine, and the like. Further examples of peroxide systems include ammonium or potassium peroxodisulfate, hydrogen peroxide, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, succinic peroxide, t-butylperoxy-2-ethylhexanoate, t-butyl hydroperoxide and the like can be mentioned.

A crosslinkable monomer can be used as a structural modifier during or after polymerization when producing the water-soluble polymer in the present invention. From the viewpoint of product stability when mixed with an isothiazoline-based compound, a water-soluble crosslinked type produced by allowing a crosslinkable monomer to exist within the range of 0.00005 to 0.050% by mass with respect to the total amount of monomers Polymers are preferred. Although it varies depending on the monomer composition and polymerization conditions, if it exceeds 0.050% by mass, the cross-linking proceeds too much and the composition becomes insoluble in water, which is not preferable for the use of the present invention. Examples of crosslinkable monomers include N,N'-methylenebis(meth)acrylamide, triallylamine, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, di 1,3-butylene glycol methacrylate, polyethylene glycol di(meth)acrylate, N-vinyl(meth)acrylamide, N-methylallylacrylamide, glycidyl acrylate, polyethylene glycol diglycidyl ether, acrolein, glyoxal, vinyltrimethoxy Examples include silane, and N,N'-methylenebis(meth)acrylamide is preferred.

In order to control the degree of polymerization, it is effective to use 0.1 to 5% by mass of isopropyl alcohol or 0.01 to 0.5% by mass of sodium formate based on the monomer.

After polymerization, if necessary, a hydrophilic surfactant called a phase inversion agent is added to make the emulsion particles covered with a film of oil more compatible with water, making it easier for the water-soluble polymer inside to dissolve. and dilute with water and use for each application. Examples of hydrophilic surfactants include cationic surfactants and nonionic surfactants with an HLB of 9 to 15, such as polyoxyethylene polyoxypropylene alkyl ethers and polyoxyethylene alcohol ethers.

The water-soluble polymer in the present invention needs to have a certain molecular weight in order to exhibit performance as a sludge dewatering agent. In the present invention, the 4% by mass saline solution viscosity (SLV; 0.5% by mass salt solution viscosity) measured with a rotational viscometer at 25 ° C. when completely dissolved so that the polymer concentration is 0.5% by mass ) can be used as an indicator of the molecular weight. The water-soluble polymer in the present invention preferably has an SLV of 5 mPa·s or more and 100 mPa·s or less, more preferably 10 mPa·s or more and 100 mPa·s or less, and even more preferably 10 mPa·s or more and 70 mPa·s or less. This 0.5% by mass salt aqueous solution viscosity is a value measured with a No. 1 rotor at 60 rpm with a Brookfield viscometer. Toki Sangyo TVB-10M or the like is used as the B-type viscometer. The polymer solution is prepared by stirring at 800 rpm for 30 minutes.
Also, the weight average molecular weight is preferably 1 million to 8 million, more preferably 2 million to 8 million, and even more preferably 2 million to 6 million.

The isothiazoline compound in the present invention includes 1,2-benzisothiazolin-3-one, N-butyl-1,2-benzisothiazolin-3-one, 2-methylisothiazolin-3-one, 5-chloro-2-methyl -4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 4,5-dichloro-2-methyl-4-isothiazolin-3-one, 2-ethyl-4-isothiazolin-3-one , 2-n-octyl-4-isothiazolin-3-one, 5-chloro-2-ethyl-4-isothiazolin-3-one, 5-chloro-2-t-octyl-4-isothiazolin-3-one, 4 ,5-dichloro-2-n-octyl-4-isothiazolin-3-one and 4,5-dichloro-2-cyclohexyl-4-isothiazolin-3-one and salts thereof are used. . Among these, 1,2-benzisothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one and salts thereof are preferred, Most preferred are 1,2-benzisothiazolin-3-ones and salts thereof. This is because when it is mixed with the water-soluble polymer of the present invention, it tends to have higher product stability than other isothiazoline compounds.

Mixing of the water-soluble polymer and the isothiazoline-based compound can be performed by preparing an aqueous solution containing the isothiazoline-based compound and then mixing it with the water-soluble polymer product. Alternatively, the isothiazoline compound may be added to the water-soluble polymer solution, or an aqueous solution of the isothiazoline compound may be prepared and then mixed with the water-soluble polymer solution. From the viewpoint of practicality, it is preferable to prepare an aqueous isothiazoline compound solution and mix it with a water-soluble polymer product to obtain a sludge dehydrating agent. In this case, the isothiazoline-based compound aqueous solution is preferably contained in an amount of 1% by mass or less relative to the sludge dehydrating agent product, depending on the concentration of the aqueous solution. This is because if the amount exceeds 1% by mass, problems may arise in the stability and solubility of the sludge dehydrating agent product. The isothiazoline compound aqueous solution is an isothiazoline compound solution containing 50% by mass or more of water.

When an aqueous solution containing an isothiazoline compound is prepared and then mixed with a water-soluble polymer product, first, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, or polyethylene glycol is used to dissolve the isothiazoline compound in the aqueous solution. , glycols such as polypropylene glycol; glycol ethers such as propylene glycol ether, diethylene glycol monobutyl ether, ethylene glycol ethyl ether and ethylene glycol monobutyl ether; alcohols such as methanol, ethanol, propanol and isopropanol;
Also, an inorganic salt may be used or used in combination at the time of dissolution. Inorganic salts include sodium chloride, potassium chloride, lithium chloride, sodium sulfate, potassium sulfate, sodium nitrate, potassium nitrate, sodium phosphate, potassium phosphate, calcium chloride, magnesium chloride, magnesium sulfate, sodium nitrate, calcium nitrate, magnesium nitrate, etc. is mentioned.

Acids or salts thereof such as sulfuric acid, hydrochloric acid, nitric acid, acetic acid, formic acid, sulfamic acid, citric acid, fumaric acid, phthalic acid, succinic acid, adipic acid, oxalic acid, malic acid, salicylic acid, etc., for adjusting the pH of aqueous solutions of isothiazoline compounds. , sodium hydroxide, potassium hydroxide, ferric sulfate, ferric chloride, ferric nitrate, copper sulfate, copper chloride, or hydrate salts thereof can be added. By adjusting the pH of the isothiazoline-based compound aqueous solution to 5.8 to 8.0, the product stability and effect of the sludge dehydrating agent in the present invention tend to be improved, which is preferable. These isothiazoline-based compound aqueous solutions are prepared by mixing under arbitrary mixing conditions using a stirrer, a mixer, a homogenizer, or the like. Forming a fine particle colloid by a mixing treatment is preferable because the diffusibility with the water-soluble polymer sample is further increased, and the effect is improved. It is preferable to adjust the isothiazoline compound concentration in the isothiazoline compound aqueous solution to 3 to 20% by mass.

Further, as the isothiazoline compound used in the present invention, those commercially available as general industrial raw materials can be used. For example, "PROXEL (registered trademark) GXL" (20% by mass of 1,2-benzisothiazolin-3-one, dipropylene glycol solution), "PROXEL (registered trademark) BDN" (1,2-benzisothiazolin-3- 35 wt. 1.3% by weight mixture of 2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one in propylene glycol), commercially available from Chemicrea, "KATHON® LX1400" (5-chloro-2 KATHON® WT (5-chloro -13.9% by weight as a 3:1 mixture of 2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one, Rohm and Haas Japan Co., Ltd. as a solution containing magnesium nitrate) Those commercially available from , etc. can be used.

The isothiazoline compound is preferably contained in an amount of 0.005 to 0.1% by mass with respect to the sludge dehydrating agent product. If it is less than 0.005% by mass, the deodorant effect and dehydration effect cannot be greatly improved, and if it exceeds 0.1% by mass, the stability of the sludge dehydrating agent product becomes poor and problems may occur in long-term storage. Because.

Although the mechanism of action of the sludge dehydrating agent in the present invention is unknown, the chemical reaction between the sulfur-based odorous component in the sludge suspension and the functional group of the isothiazoline compound provides an odorous component-adsorbing action. It is presumed that the blocking of the sulfur-based odorous components that act as sludge enhances the cross-linking adsorption action between the water-soluble polymer and the suspended solids in the sludge, thereby improving the coagulation effect. That is, it is considered that the effect of the sludge dehydrating agent of the present invention is exhibited by the synergistic effect of the odorous component adsorption action and the cross-linking adsorption action.

Sludge species to which the sludge dehydrating agent of the present invention can be applied include excess sludge generated during biological treatment such as paper manufacturing wastewater, chemical industrial wastewater, and food industrial wastewater, or organic sludge generated in the treatment of urban sewage, night soil, and industrial wastewater. Sludge (so-called raw sludge, surplus sludge, mixed raw sludge, digested sludge, sedimentation/floating sludge and mixtures thereof), livestock sludge, etc. However, the organic content ratio is particularly difficult to dewater and tends to cause odor problems. effective for organic sludge with a high Specifically, the sludge has an organic matter amount (VSS, ignition loss in suspended solids, mass % vs. SS) of 45% by mass or more, which is an indicator of organic matter.
In recent years, in these organic sludges, VSS and VTS (ignition loss in evaporation residue, mass % vs. TS) tend to increase, and the effect of the sludge dehydrating agent of the present invention compared to conventional sludge dehydrating agents becomes more pronounced, sludge having a VSS of 60% by mass or more is preferable, and 70% by mass or more is more preferable. In addition, various measured values are based on the measurement based on the standard method (sewage test method).

The sludge dehydrating agent in the present invention is diluted with water to an arbitrary concentration and added to these sludges. A range of 0.01 to 1.0 mass % is preferred. The addition rate to sludge varies depending on the type of sludge and dehydrator type, but is 1 to 1000 ppm with respect to the amount of sludge liquid. The type of dehydrator used can be a belt press, a centrifugal dehydrator, a screw press, a multi-disc dehydrator, a rotary press, a filter press, or the like. Inorganic flocculants such as aluminum sulfate, aluminum chloride, polyaluminum chloride, polyferrous sulfate, polyferric sulfate, and ferric chloride may also be used in combination.

The sludge dewatering agent in the present invention will be specifically described below, but the present invention is not limited to the following examples.

(Production of water-soluble polymer sample)
Water-soluble polymer samples A to in the present invention are prepared by the conventional method of water-in-oil emulsion disclosed in JP-A-59-130397, JP-A-10-140496, JP-A-2011-99076, etc. made C. These products are widely used as sludge dewatering agents. These compositions and physical properties are shown in Table 1.

単量体；ＤＭＱ：アクリロイルオキシエチルトリメチルアンモニウム塩化物、ＡＡＭ：アクリルアミド、ＡＡＣ：アクリル酸
形態；ＥＭ：油中水型エマルジョン
０．２質量％水溶液粘度：高分子濃度が０．２質量％になるように水で溶解したときの２５℃において測定した粘度（ｍＰａ・ｓ）。
０．５質量％塩水溶液粘度：４質量％食塩水中に高分子濃度が０．５質量％になるように溶解したときの２５℃において測定した粘度（ｍＰａ・ｓ）。 (Table 1)

Monomer; DMQ: acryloyloxyethyltrimethylammonium chloride, AAM: acrylamide, AAC: acrylic acid Form; EM: 0.2% by mass aqueous solution of water-in-oil emulsion Viscosity: polymer concentration becomes 0.2% by mass Viscosity (mPa·s) measured at 25° C. when dissolved in water as
Viscosity of 0.5% by weight aqueous salt solution: Viscosity (mPa·s) measured at 25° C. when the polymer concentration is 0.5% by weight in 4% by weight saline solution.

(Preparation of isothiazoline-based compound aqueous solution)
To a dipropylene glycol solution of 1,2-benzisothiazolin-3-one, ferric sulfate heptahydrate, 10% by mass sodium hydroxide, and pure water were added in a ratio of 24:15:4:57% by mass, respectively. , mixing treatment, and a 5% by mass aqueous solution (pH 6) of 1,2-benzisothiazolin-3-one was prepared.

(Example 1)
(Preparation of sludge dewatering agent)
A sludge dehydrating agent sample containing 0.01 to 0.03% of the isothiazoline compound relative to the sludge dehydrating agent product was prepared by mixing the water-soluble polymer sample A in Table 1 and the aqueous solution of the isothiazoline compound. . Similarly, the water-soluble polymer samples B and C were mixed with the isothiazoline compound aqueous solution to prepare sludge dehydrating agent samples containing 0.01 to 0.03% of the isothiazoline compound relative to the sludge dehydrating agent product. These were used as Example 1 as sludge dewatering agents in the following practical test examples.

(Test Example 1, sludge dehydration test)
Livestock sludge generated from a livestock farm (pH 7.2, electrical conductivity 146 mS/m, SS content 14250 mg/L, VSS 89.5 mass%, VTS 87.5 mass%, M-alkalinity 562 mg/L, anion content 5.81 meq /L) was subjected to a dehydration test.
200 mL of sludge was collected in a polybeaker, and a 0.2% by mass aqueous solution of a sludge dehydrating agent containing 0.02% by mass (relative to the sludge dehydrating agent product) of the water-soluble polymer sample A of Example 1 and an isothiazoline compound was added. After 200 ppm of sludge liquid was added (polymer pure content), the mixture was stirred upside down 10 times, filtered through 40 mesh, and the amount of filtered water was measured. Thereafter, the sludge was dehydrated using a nylon filter cloth (#202) at a press pressure of 3 kg/cm ² for 30 seconds, and the moisture content of the cake (dried at 105°C for 20 hours) was measured. The same test was conducted under the same conditions for the water-soluble polymer sample B of Example 1 and a sludge dehydrating agent containing 0.02% by mass of an isothiazoline compound (relative to the sludge dehydrating agent product). These results are shown in Table 2.

(Comparative Test Example 1, Sludge Dehydration Test) Using the same sludge as in Experimental Test Example 1, water-soluble polymer samples A and B in Table 1 were used to conduct the same test as in Experimental Test Example 1. These results are shown in Table 2.

(Table 2)

(Practical test example 2, odor measurement test)
200 mL of the same sludge as in Test Example 1 was collected in a polybeaker, and 0.02% by mass of the sludge dehydrating agent containing the water-soluble polymer sample A of Example 1 and an isothiazoline compound (relative to the sludge dehydrating agent product) was added. Add 100 ppm of 2% by mass aqueous solution to the sludge liquid (polymer pure content), stir upside down 10 times, put 100 mL of sludge filtered through 40 mesh into a 300 mL Erlenmeyer flask, and attach a rubber stopper to the Erlenmeyer flask with a rubber tube. was sealed and fixed in a 40° C. water bath, and after 3 hours the concentration of hydrogen sulfide (H ₂ S) was measured with a gas detector tube (manufactured by Gastech).
The same test was conducted under the same conditions for the water-soluble polymer sample B of Example 1 and a sludge dehydrating agent containing 0.02% by mass of an isothiazoline compound (relative to the sludge dehydrating agent product). These results are shown in Table 3.

(Comparative Test Example 2, Odor Measurement Test) Using the same sludge as in Experimental Test Example 1, water-soluble polymer samples A and B in Table 1 were used to conduct the same test as in Experimental Test Example 2. These results are shown in Table 3.

(Table 3)

In Experimental Test Examples 1 and 2 in which the sludge dehydrating agent of the present invention was added, compared to the case of using the same kind of water-soluble polymer sample in Comparative Test Examples 1 and 2, the amount of filtered water was large, the moisture content of the cake was reduced, and It was found that the hydrogen sulfide concentration decreased, and the dehydrating effect and deodorizing effect of the sludge dehydrating agent containing the water-soluble polymer and the isothiazoline compound in the present invention were excellent.

(Test Example 3, sludge dehydration test)
Excess sludge generated from a food factory (pH 7.2, electrical conductivity 199 mS / m, SS content 11750 mg / L, VSS 74.5 mass%, VTS 70.6 mass%, M-alkalinity 980 mg / L, anion amount 6.54 meq /L) was subjected to a dehydration test.
200 mL of sludge was collected in a polybeaker, and a 0.2% by mass aqueous solution of a sludge dehydrating agent containing 0.01% by mass (relative to the sludge dehydrating agent product) of the water-soluble polymer sample A of Example 1 and an isothiazoline compound was added. After adding 175 ppm of sludge liquid (pure polymer content), the mixture was transferred to a beaker and stirred 20 times, filtered through 40 mesh, and the amount of filtrate was measured. Thereafter, the sludge was dehydrated using a nylon filter cloth (#202) at a press pressure of 3 kg/cm ² for 60 seconds, and the moisture content of the cake (dried at 105°C for 20 hours) was measured. Also, using other sludge dehydrating agent samples of Example 1, similar tests were carried out under similar conditions. These results are shown in Table 4.

(Comparative Test Example 3, Sludge Dehydration Test) Using the same sludge as in Experimental Example 3, water-soluble polymer samples A to C in Table 1 were used to conduct the same test as in Experimental Example 3. These results are shown in Table 4.

(Table 4)

(Test Example 4, sludge dehydration test)
Pressurized flotation sludge generated from a food factory (pH 6.5, electrical conductivity 209 mS/m, SS content 81500 mg/L, VSS 95.1 mass%, VTS 94.6 mass%, M-alkalinity 733 mg/L, anion amount 4.85 meq/L) was performed.
200 mL of sludge was collected in a polybeaker, and a 0.2% by mass aqueous solution of a sludge dehydrating agent containing 0.01% by mass (relative to the sludge dehydrating agent product) of the water-soluble polymer sample A of Example 1 and an isothiazoline compound was added. After 200 ppm or 350 ppm of sludge liquid was added (polymer pure content), the mixture was transferred to a beaker and stirred 20 times, filtered through 40 mesh, and the amount of filtered water was measured. Thereafter, the sludge was dehydrated using a nylon filter cloth (#202) at a press pressure of 3 kg/cm ² for 60 seconds, and the moisture content of the cake (dried at 105°C for 20 hours) was measured. Also, using other sludge dehydrating agent samples of Example 1, similar tests were carried out under similar conditions. These results are shown in Table 5.

(Comparative Test Example 4, Sludge Dehydration Test) Using the same sludge as in Experimental Example 4, and using the water-soluble polymer sample A in Table 1, the same test as in Experimental Example 4 was carried out. These results are shown in Table 5.

(Table 5)

(Test Example 5, sludge dehydration test)
Excess night soil sludge generated from a livestock farm (pH 7.0, electrical conductivity 719 mS/m, SS content 17500 mg/L, VSS 40.0 mass%, VTS 39.8 mass%, M-alkalinity 664 mg/L, anion amount 9. 83 meq/L) was tested for dehydration.
200 mL of sludge was collected in a polybeaker, and a 0.2% by mass aqueous solution of a sludge dehydrating agent containing 0.02% by mass (relative to the sludge dehydrating agent product) of the water-soluble polymer sample A of Example 1 and an isothiazoline compound was added. After 75 ppm of sludge liquid was added (polymer pure content), the mixture was inverted and stirred 10 times, filtered through 40 mesh, and the amount of filtered water was measured. Thereafter, the sludge was dehydrated using a nylon filter cloth (#202) at a press pressure of 3 kg/cm ² for 30 seconds, and the moisture content of the cake (dried at 105°C for 20 hours) was measured. Also, using other sludge dehydrating agent samples of Example 1, similar tests were carried out under similar conditions. These results are shown in Table 6.

(Comparative Test Example 5, Sludge Dehydration Test) Using the same sludge as in Experimental Test Example 5, water-soluble polymer samples A and B in Table 1 were used to conduct the same test as in Experimental Test Example 5. These results are shown in Table 6.

(Table 6)

(Test Example 6, sludge dehydration test)
Sludge sludge generated from a pharmaceutical factory (pH 6.9, electrical conductivity 167 mS/m, SS content 21500 mg/L, VSS 18.6 mass%, VTS 18.5 mass%, M-alkalinity 21 mg/L, anion content 4.06 meq /L) was subjected to a dehydration test.
200 mL of sludge was collected in a polybeaker, and a 0.2% by mass aqueous solution of a sludge dehydrating agent containing 0.02% by mass (relative to the sludge dehydrating agent product) of the water-soluble polymer sample A of Example 1 and an isothiazoline compound was added. After adding 320 ppm of sludge liquid (pure polymer content), the mixture was transferred to a beaker and stirred 20 times, filtered through 40 mesh, and the amount of filtrate was measured. Thereafter, the sludge was dehydrated using a nylon filter cloth (T-1179L) at a press pressure of 3 kg/cm ² for 60 seconds, and the moisture content of the cake (dried at 105°C for 20 hours) was measured. Also, using other sludge dehydrating agent samples of Example 1, similar tests were carried out under similar conditions. These results are shown in Table 7.

(Comparative Test Example 6, Sludge Dehydration Test) Using the same sludge as in Experimental Test Example 6, water-soluble polymer samples A to C in Table 1 were used to conduct the same test as in Experimental Test Example 6. These results are shown in Table 7.

(Table 7)

(Test Example 7, sludge dehydration test)
Night soil sludge generated from a sewage treatment plant (pH 6.6, electrical conductivity 269 mS / m, SS content 2750 mg / L, VSS 90.0 mass%, VTS 76.5 mass%, M-alkalinity 790 mg / L, anion amount 1. 30 meq/L) was tested for dehydration.
200 mL of sludge was collected in a polybeaker, and a 0.2% by mass aqueous solution of a sludge dehydrating agent containing 0.02% by mass (relative to the sludge dehydrating agent product) of the water-soluble polymer sample C of Example 1 and an isothiazoline compound was added. After 40 ppm or 80 ppm of sludge liquid was added (polymer pure content), the mixture was transferred to a beaker and stirred 20 times. Thereafter, the sludge was dehydrated using a nylon filter cloth (#202) at a press pressure of 3 kg/cm ² for 60 seconds, and the moisture content of the cake (dried at 105°C for 20 hours) was measured. These results are shown in Table 7.

(Comparative Test Example 7, Sludge Dehydration Test) Using the same sludge as in Experimental Test Example 7 and water-soluble polymer sample C or A in Table 1, the same test as in Experimental Test Example 7 was carried out. These results are shown in Table 8.

(Table 8)

In Experimental Test Examples 3 to 7 in which the sludge dehydrating agent of the present invention was added, compared to the case of using the same kind of water-soluble polymer sample in Comparative Test Examples 3 to 7, the amount of filtered water was large, and the moisture content of the cake was reduced. It was found that the sludge dehydrating agent containing a water-soluble polymer and an isothiazoline compound in the present invention has an excellent dehydrating effect on a wide variety of sludges.

(Test Example 8, odor measurement test)
Excess night soil sludge generated from a pig farm (pH 7.4, electrical conductivity 708 mS / m, SS content 23500 mg / L, VSS 69.1 mass%, VTS 63.4 mass%, M-alkalinity 2613 mg / L, anion amount 8. 73 meq/L) was subjected to an odor measurement test.
200 mL of sludge was collected in a polybeaker, and a 0.2% by mass aqueous solution of a sludge dehydrating agent containing 0.02% by mass (relative to the sludge dehydrating agent product) of the water-soluble polymer sample A of Example 1 and an isothiazoline compound was added. Add 300 ppm of sludge liquid (polymer pure content), transfer to a beaker and stir 20 times, put 100 mL of sludge filtered through 40 mesh into a 300 mL Erlenmeyer flask, seal the Erlenmeyer flask with a rubber stopper attached with a rubber tube, 40 ° C. It was fixed in a water bath, and the hydrogen sulfide (H ₂ S) concentration after 2 hours was measured with a gas detector tube (manufactured by Gastech). Also, using other sludge dehydrating agent samples of Example 1, similar tests were carried out under similar conditions. These results are shown in Table 9.

(Comparative Test Example 8, Odor Measurement Test) Using the same sludge as in Experimental Test Example 8, water-soluble polymer samples A and B in Table 1 were used to conduct the same test as in Experimental Test Example 8. These results are shown in Table 9.

(Table 9)

(Test Example 9, odor measurement test)
Raw sludge generated from a sewage treatment plant (pH 6.7, electrical conductivity 114 mS / m, SS content 6000 mg / L, VSS 87.5 mass%, VTS 84.6 mass%, M-alkalinity 260 mg / L, anion amount 1. 48 meq/L) was subjected to an odor measurement test.
200 mL of sludge was collected in a polybeaker, and a 0.2% by mass aqueous solution of a sludge dehydrating agent containing 0.01% by mass (relative to the sludge dehydrating agent product) of the water-soluble polymer sample A of Example 1 and an isothiazoline compound was added. Add 100 ppm of sludge liquid (polymer pure content), transfer to a beaker and stir 20 times, put 200 mL of sludge filtered through 40 mesh into a 300 mL Erlenmeyer flask, seal the Erlenmeyer flask with a rubber stopper attached with a rubber tube, 40 ° C. It was fixed in a water bath, and hydrogen sulfide (H ₂ S) and methyl mercaptan (CH ₃ SH) concentrations after 1 hour were measured with a gas detector tube (manufactured by Gastech). Also, using other sludge dehydrating agent samples of Example 1, similar tests were carried out under similar conditions. These results are shown in Table 10.

(Comparative Test Example 9, Odor Measurement Test) Using the same sludge as in Experimental Test Example 9, water-soluble polymer samples A to C in Table 1 were used to conduct the same test as in Experimental Test Example 9. These results are shown in Table 10.

(Table 10)

In Experimental Test Examples 8 and 9 in which the sludge dehydrating agent of the present invention was added, the concentration of hydrogen sulfide or methyl mercaptan decreased compared to the case of using the same kind of water-soluble polymer sample in Comparative Test Examples 8 and 9, respectively. , it was found that the deodorant effect of the sludge dehydrating agent containing the water-soluble polymer and the isothiazoline compound in the present invention is excellent.

When the sludge dehydrating agent containing a water-soluble polymer and an isothiazoline-based compound in the present invention is applied to a wide variety of sludges, especially organic sludge containing a large amount of organic matter, it deodorizes or suppresses sulfur-based odors, and sludge dewatering performance is improved. was confirmed to improve.

Claims (5)

1 to 99 mol% of the cationic monomer represented by the following general formula (1), 0 to 99 mol% of the anionic monomer represented by the following general formula (2) and 1 to 99 mol% of the nonionic monomer A sludge dehydrating agent containing a water-soluble polymer and an isothiazoline compound having 99 mol % of constituent units.

General formula (1)
_{A _ _ _} represents oxygen or NH, B represents an alkylene group having 2 to 4 carbon atoms, and X ₁ ^- represents an anion.

general formula (2)
R ₅ is hydrogen, a methyl group or a carboxymethyl group, Q is SO ₃ ^- , C ₆ H ₄ SO ₃ ^- , CONHC(CH ₃ ) ₂ CH ₂ SO ₃ ^- , C ₆ H ₄ COO ^- or COO ^- , R ₆ represents hydrogen or COOY ₂ , Y ₁ or Y ₂ represents hydrogen or a cation, respectively. The isothiazoline compound is 1,2-benzisothiazolin-3-one, N-butyl-1,2-benzisothiazolin-3-one, 2-methylisothiazolin-3-one, 5-chloro-2-methyl-4 -isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 4,5-dichloro-2-methyl-4-isothiazolin-3-one, 2-ethyl-4-isothiazolin-3-one, 2 -n-octyl-4-isothiazolin-3-one, 5-chloro-2-ethyl-4-isothiazolin-3-one, 5-chloro-2-t-octyl-4-isothiazolin-3-one, 4,5 -dichloro-2-n-octyl-4-isothiazolin-3-one and 4,5-dichloro-2-cyclohexyl-4-isothiazolin-3-one and salts thereof The sludge dewatering agent according to claim 1. 3. The sludge dewatering agent according to claim 1, wherein the sludge dewatering agent is in the form of a water-in-oil emulsion. The sludge dehydrating agent according to claim 1 or 2, wherein the content of said isothiazoline-based compound is 0.005 to 0.1% by mass relative to the sludge dehydrating agent product. A method for dewatering sludge, comprising adding the sludge dewatering agent according to any one of claims 1 to 4 to sludge and dehydrating the sludge.