JPH029500A - Method for dehydrating sludge and sludge dehydrating agent - Google Patents

Abstract

PURPOSE:To perform dehydration at high dehydration efficiency by mixing water-in-oil type emulsion having a cationic and an anionic high molecular flocculating agent in the dispersed aq. phase to obtain a sludge dehydrating agent and mixing this dehydrating agent with specified acid and adding this mixture to sludge. CONSTITUTION:A sludge dehydrating agent is obtained by mixing water-in-oil type emulsion which has a cationic high molecular flocculating agent in a dispersed aq. phase and holds an organic solvent as a continuous phase with water- in-oil type emulsion which has an anionic high molecular flocculating agent in the dispersed aq. phase and holds the organic solvent as the continuous phase. This sludge dehydrating agent is mixed with acid wherein the rate of utilization is regulated to two times equivalent or more of M-alkalinity of dissolving water in the dissolving water. Flocculated floc is formed by adding the obtained mixed liquid to sludge and thereafter dehydrated. Since both components of a cationic component and an anionic component are utilized, dehydration efficiency is made extremely high. Further, both components are not allowed to react with each other and therefore its handling is made easy.

Description

Detailed Description of the Invention [Field of Application in Industry A] The present invention relates to a sludge dewatering method and a sludge dehydrating agent, and uses a combination of cationic and anionic emulsion polymers to form strong flocs and dewater the sludge. The present invention relates to a sludge dewatering method and a sludge dewatering agent that can significantly improve efficiency.

[Prior Art] In the treatment of sewage, human waste, or each FF1 industrial wastewater, sludge such as surplus sludge and IJJ collected sludge is generated. As a dehydrating agent for such sludge, organic polymer flocculants have recently come to be used instead of conventional non-mva agents.

The mainstream of current sludge dewatering methods is sludge dewatering methods.
This method uses a nonionic or cationic polymer flocculant. In this method, the ranges of the optimum ionic strength and optimum molecular density of the polymer flocculant for sludge are both narrow, making it difficult to always obtain a good dewatering condition.

On the other hand, it is known that when coagulating and dewatering sludge, a cationic flocculant is added to the sludge and then an anionic flocculant is added to form flocs with good dewatering properties. In this case, when preparing an aqueous solution of flocculants, if both flocculants are dissolved in the same water, they will react, so it is necessary to prevent ion dissociation of one of them. Therefore, a method has been proposed in which anionic and cationic powdered polymer flocculants and powdered acids are mixed and used as an aqueous solution (for example, JP-A-58-216707;
-43800), this method suppresses the dissociation of the carboxyl group of an anion flocculant by acid.

[Problems to be Solved by the Invention] Among the above conventional methods, the method described in JP-A-58-216707 uses powdered polymer, which has poor solubility and requires more than 2 hours to completely dissolve. However, there is a drawback that the melting equipment for the same usage amount is 2 to 5 times larger than a normal case.

On the other hand, in the method of Japanese Patent Publication No. 60-43800, depending on the target sludge, inorganic metal salts must be used together.
Operability and workability are complicated.

An object of the present invention is to solve the above conventional problems and provide a sludge dewatering method and a sludge dewatering agent that can dewater sludge with extremely high dewatering efficiency.

[Means for Solving the Problems] The sludge dewatering method of the present invention comprises a water-in-oil emulsion having a cationic polymer flocculant in a dispersed water phase and an organic solvent as a continuous phase, and an anionic polymer. A water-in-oil emulsion containing a flocculant in a dispersed water phase and an organic solvent as a continuous phase is mixed with an acid in dissolved water, and the resulting mixture is added to sludge to form coagulated flocs. , a method for dehydrating sludge by dehydration, characterized in that the proportion of acid used is at least twice the equivalent of the M-alkalinity (calculated as CaCOs) of the dissolved water.

The sludge dewatering agent of the present invention comprises a water-in-oil emulsion having a cationic polymer flocculant in the dispersed aqueous phase and an 8M solvent as a continuous phase, and an anionic polymer flocculant in the dispersed aqueous phase. and a water-in-oil emulsion having an organic solvent as a continuous phase.

That is, as a result of intensive studies by the present inventors to obtain a highly efficient sludge dewatering agent using a polymer instead of a powdered polymer,
We obtained the knowledge that even if a cationic emulsion polymer and an anionic emulsion polymer are mixed, the cationic polymer and anionic polymer do not react, and developed the sludge dewatering method and sludge dehydrating agent of the present invention that use these polymers together. did.

The present invention will be explained in detail below.

In carrying out the sludge dewatering method of the present invention, it is advantageous to use the sludge dewatering agent of the present invention.

In the present invention, the cationic polymer flocculant is a cationic unit represented by the following formula (I), or a tertiary salt thereof (hydrochloric acid, sulfuric acid, li# acid, formic acid, acetic acid, etc.) or a quaternary salt thereof. (meth)acrylamide, (meth)acrylonitrile, alkyl (meth)acrylate ester,
1f selected from structural units such as vinyl acetate and styrene!
A copolymer with the above nonionic monomer; or a cationic unit represented by the above formula (I) and the following formula (II
) and the like, but are not limited to these.

Examples of anionic polymer flocculants for anionic emulsion polymers include those disclosed in Japanese Patent Publication No. 52-18224, i.e., acrylic acid, methacrylic acid, or alkali metal salts thereof, represented by the following formula: Homopolymer of one or more anionic groups selected from ammonium salts and carboxylic acids thereof: Anionic units represented by the above general formula (II) and (meth)
Acrylamide, (meth)acrylonitrile, (meth)
A copolymer with one or more nonionic units selected from structural units such as acrylic acid alkyl ester, vinyl acetate, and styrene; or a terpolymer with an anionic unit represented by the above general formula (II). ; etc., but are not limited to these.

A water-in-oil (WO type) emulsion having such a cationic polymer flocculant or anionic polymer flocculant in a dispersed aqueous phase and an organic solvent as a continuous phase can be prepared, for example, by the following method (1) or (2). It can be easily manufactured by this method.

■ Emulsion polymerization method or suspension polymerization method: Polymerization that is soluble in organic solvents that forms a continuous phase by keeping the monomers that produce the desired polymer flocculant in a completely emulsified state in the presence of a surfactant. Emulsion polymerization is carried out using a catalyst, or J# polymer is suspended in a continuous phase using a surfactant, mainly by selective stirring, and a polymerization catalyst that is soluble in the monomer and insoluble in the continuous phase is added. Suspension polymerization is carried out using

In this case, the surfactant is one that can form a W10 type emulsion by dispersing the monomer-water mixture used in an organic solvent, that is, a surfactant with an HLB value (Hydrophi 1
ir Lipophilir Balance)3
~10 and the hydrophilic group is relatively small compared to the lipophilic group,
For example, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene fatty acid esters, or fatty acid esters of polyhydric alcohols, which have a relatively low number of oxyethylene group additions, are suitable, and the amount used depends on the reaction. It is preferably 40% by weight or less based on the monomer-water mixture used.

In addition, when polymerization is reverse phase emulsion polymerization, oil-soluble catalysts such as benzoyl peroxide and azobisisobutyronitrile are used as polymerization catalysts. It is also possible to use a redox catalyst system in combination with a reducing agent and a reducing agent. The amount of these catalysts to be used is determined by considering the catalyst activation rate, reaction temperature,
It is necessary to adjust the molecular weight of the target polymer flocculant as appropriate, but - numerically, it is 0 to the amount of monomer used.
．． In the case of reversed-phase suspension polymerization, water-soluble catalysts such as persulfates and hydrogen peroxide are preferably used in an amount of 0.001 to 0.1 mol %.
These polymerization catalysts, which are preferably 1 mol %, can be added to the total amount of the monomer-water mixture used, but
There is a method in which the entire amount is added to the monomer-water mixture that is mixed with a solvent and emulsified at the beginning of polymerization, and the polymerization catalyst is not included in the mixture that is divided and added sequentially later. Particularly preferred.

■ Method of adding polymer II admixture powder to the W10 type emulsion and dissolving it in the dispersed aqueous phase: W10 type using an emulsifier, preferably a low HLB emulsifier, if necessary, by high-speed stirring method or ultrasonic method, etc. Adjust the emulsion, preferably the average particle size is 5 mm or less,
More preferably, add polymer flocculant powder pulverized to an average particle size of 1 to 5 μm, and stir with a stirring device such as a stirrer shaker or homogenizer to dissolve the polymer flocculant powder in the dispersed water phase of the W10 emulsion. let

In addition, in the present invention, the organic solvent constituting the continuous phase of the W10 type emulsion is one that hardly dissolves the cationic and anionic polymer flocculants and water, does not adversely affect the polymerization reaction, and is easy to recover and use. Specifically, linear or branched saturated hydrocarbons such as normal hexane and isopentane, which have a carbon number of 7 or less and a boiling point above room temperature, or aromatic hydrocarbons such as toluene, or these A mixture of solvents is used.

In the present invention, W10 containing a cationic polymer flocculant
The volume ratio of organic solvent to water in the mold emulsion is 7:
The ratio is 1 to 1:1, preferably about 1:1. Also, W1
The concentration of cationic polymer flocculant in type 0 emulsion is 1
It is 5 to 65% by weight, preferably 30 to 60% by weight.

In addition, the volume ratio of the organic solvent to water in the W10 type emulsion containing the anionic polymer flocculant is 7=1 to 1:1.
, preferably about tit.

Also, the concentration of anionic polymer flocculant in the W10 emulsion is 15 to 65! ! Amount%, preferably 30-601
! The amount is %.

There is no particular restriction on the mixing ratio of the W10 type emulsion containing such a cationic polymer flocculant and the W10 type emulsion containing an anionic polymer flocculant, and it is 1 to 99%.
: Can be selected within a wide range of 99 to Ilt amount %.

In general, although it varies depending on the properties of the sludge to be treated, the weight ratio of the cationic polymer flocculant and anionic polymer flocculant contained in each W10 emulsion is 90 =
10-10;90, preferably 80:20-20:80
are selected to be within the range of .

In the sludge dewatering method of the present invention, the W10 type emulsion containing the above-mentioned cationic polymer flocculant and the W10 type emulsion containing the anionic polymer flocculant are used in combination with an acid. Prevents dissociation of carboxyl groups of molecular flocculants. Acids used include sulfuric acid, hydrochloric acid, sodium hydrogen sulfate, sodium dihydrogen phosphate, boric acid, sulfamic acid, maleic acid, malic acid, malonic acid, succinic acid, tartaric acid, oxalic acid, citric acid, fumaric acid, etc. Examples include, but are not limited to.

If the amount of these acids used is too small, it will not be possible to obtain a good dissolution state of W10 type emulsicon, so the M-alkalinity (CaCOat
The amount should be at least 2 times equivalent, preferably 4 times or more, relative to Jl calculation).

In addition, when the sludge dewatering agent of the present invention is added to sludge,
It is sufficient that the W10 type emulsion containing a cationic polymer flocculant and the W10 type emulsion containing an anionic polymer flocculant are mixed, and these may be provided in advance in a mixed state, or each may be provided separately. Therefore, as the method of adding it, for example, the following methods 0 to 2 can be mentioned.

(2) A W10 type emulsion containing a cationic polymer flocculant, a W10 type emulsion containing an anionic polymer flocculant, and an acid aqueous solution are each added to a dissolution tank, mixed, and added to the sludge.

(2) Add an acid aqueous solution to a mixture of the cationic polymer flocculant-containing W10 emulsion and the anionic polymer flocculant-containing W10 emulsion, mix, and add to the sludge.

■ A mixture of W10 emulsion containing an anionic polymer flocculant and an acid aqueous solution, and W containing a cationic polymer flocculant.
Mix with Type 10 emulsion and add to the sludge.

The sludge to be treated in the present invention includes anaerobic digested sludge of human waste, aerobic digested sludge of human waste, human waste septic tank sludge, human waste distillation desorption liquid, sewage, surplus sludge in activated sludge treatment of various industrial wastewater, and sewage. First settling tank sludge, human waste, flocculated sludge generated during tertiary treatment of sewage, etc., each f! Examples include, but are not limited to, coagulated sludge of industrial wastewater.

The amount of the sludge dehydrating agent of the present invention is determined by the properties of sludge (PH, S
(S, VSS, electrical conductivity, etc.), but numerically, W10 type emulsion containing a cationic polymer flocculant and WZO type emulsion containing an anionic polymer flocculant for suspended solids (SS) of sludge SS with the total amount of
In contrast, it is set to about 0.1% to 5%.

By adding the sludge dewatering agent of the present invention to the sludge and stirring it according to the methods ① to ① above, the cationic polymer flocculant neutralizes the charge (negative) of SS in the sludge, and this neutralization This produces fine flocs, and since the pH value is high as that of sludge, the anionic polymer flocculant becomes anionic, which causes the fine flocs to grow into coarser and stronger flocs. . This frock is a 5! , has excellent facultability and dehydration properties.

Stirring during aggregation is not limited to stirring by a stirring blade in the stirring tank, but may also be by Ii in the piping. In the case of a stirring tank equipped with a stirrer, the circumferential speed of the stirring blade is set to 0.5 as a guide.
~5m/,,c.

The flocs generated by coagulation are fed as they are or after removing the separated water to a dehydrator and dehydrated in the same manner as the conventional method. Examples of dehydrators include centrifugal dehydrators, vacuum dehydrators, belt press type dehydrators, Conventionally used dehydrators such as screw presses or filter presses can be used.

In addition, in the present invention, inorganic flocculants such as aluminum sulfate, polyaluminum chloride, and ferric chloride can also be used together with the sludge dewatering agent of the present invention.

[Function] In the present invention, since both the cationic component and the anionic component are used, it is possible to obtain a coagulated floc with extremely high dehydration efficiency, large size, and high strength. Moreover, since both of these components are made into W10 type emulsions, they do not react with each other and can be stored in the same storage tank, making handling easy. Furthermore, since it is a W10 type emulsion, the dissolution time is faster than that of powdered emulsions.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Examples 1-9. Comparative Examples 1 to 3 W10 type emulsion containing a cationic polymer flocculant was prepared using a cationic emulsion polymer (containing 401i mass % of homopolymer of methyl chloride quaternized dimethylaminoethyl methacrylate, hereinafter referred to as rE CI
) is anionic polymer flocculant-containing W10
Anionic emulsion polymer (as type emulsion)
It contains 40 fifi% of a copolymer of acrylic acid and acrylamide in a molar ratio of 2:8. Below, this is referred to as rEA I
Use ECI (21 parts) and EA in advance.
1 (1 part by weight) was dissolved in dissolution water to which a predetermined amount of acid (HCfL) shown in Table 1 was added to give a concentration of 1% by weight, and the state of dissolution was observed in B. In addition, it was added to human waste lA buried mixed sludge with the following properties at an amount of 200 mg/λ,
A flocculation test was conducted to examine the size of the flocs produced.

The results are shown in Table 1.

Note that the M-alkalinity of the dissolved water was adjusted using a NaHCOz reagent.

k1 亙 1 り 11 pH near, 0 SS: 2.7% VSS near 3.9%/SS Fiber content: 2.7%/55 As is clear from the M1 table, the amount of acid used is the M of the dissolved water. −
Examples 10 to 1 that the alkalinity is twice equivalent or more
5. Comparative Examples 4 to 11 Cationic emulsion polymer EC1i and anionic emulsion polymer EAI and HCl2 (reagent: containing 35% by weight of HCA) as an acid were mixed at the mixing ratio shown in Table 2, and the active ingredient concentration was 0. Adjust to 4% by weight,
It was added to the same human waste treated mixed sludge as used in Example 1 in the amounts shown in Table 3 to generate flocs. This material was poured onto a Buchner funnel lined with 100 mesh nylon 5 mulberry cloth (Nutsche test), and the amount of liquid at the third tip was measured after 20 seconds. The results are shown in Table 3.

A dehydration test was conducted in the same manner as in Example 3. The results are shown in Table N4.

1 person plate hill engineered bean j pH: 6.0 SS: 2.2% VSS: 77.6%/5S Ta fiber: 19.6%/SS Table 4 Examples 16-19. Comparative Examples 12 to 10 Samples B-2, 3, 4, and 5 in Table 2 were added to sewage mixed raw sludge with the following properties in the amounts shown in Table 4 in Tables 3 and 4.
From the table, it is clear that according to the method of the present invention, human waste treatment mixed sludge and sewage mixed raw sludge can be efficiently dewatered.

Example 4 A comparison was made in solubility between the sludge dewatering agent of the present invention and the sludge dehydrating agent disclosed in JP-A-58-216707.

75 g of a homopolymer of methyl chloride quaternized dimethylaminoethyl methacrylate as a cationic polymer aggregating agent powder, and 25 g of a copolymer of acrylic acid and acrylamide in a ratio of 2:8 as an anionic polymer flocculant powder. are combined and diluted with an acid aqueous solution (HCIL: 14
When dissolving the compound at a concentration of 0.5% by weight in an aqueous solution containing 6 mg/IL, the dissolution time was 2 hours. For this reason, when using ffiloOKg/day (4.2Kg/Hr),
According to the calculation formula below, 16,801 or more dissolving tanks are required.

On the other hand, in the sludge dewatering agent of the present invention, the cationic emulsion polymer and anionic emulsion polymer are blended so that the active ingredients are in the same amount as the powder, and dilution water with an M alkalinity of 50 mg-Ca CO3/f is used. ,
When dissolving 1.25% by weight in an aqueous solution containing 146mg/f as HCl2, the dissolution time is 10 minutes, so the amount of sludge dehydrating agent used is 250Kg/day (10.4Kg/Hr)
In this case, it is clear from the following calculation formula that a dissolution tank of approximately 140 IL is sufficient.

[Effects of the Invention] As detailed above, according to the present invention, (1) Since both the anionic component and the cationic component are used, the sludge flocculation efficiency is extremely high.

■ Since both components do not react and become insolubilized, they can be stored in one storage tank.

■ There is no need to use inorganic metal salts, improving process operability and workability.

■ Since it takes a short time to completely dissolve the sludge dewatering agent, it is possible to downsize the dissolving equipment.

■ The resulting coagulated flocs are large and strong, resulting in the following effects.

■ The amount of sludge treated can be increased by improving gravity and turbidity.

■ Since it has good peelability even with strong squeezing pressure, it is possible to lower the water content of the dehydrated cake.

■ Since it has good peelability, recovery of sludge solids can be improved.

With these effects, it is possible to easily and efficiently dewater various types of sludge.

Representative Patent Attorney Tsuyoshi Shigeno

Claims (2)

[Claims] (1) A water-in-oil emulsion with a cationic polymer flocculant in the dispersed aqueous phase and an organic solvent as a continuous phase, and a water-in-oil emulsion with an anionic polymer flocculant in the dispersed aqueous phase and an organic solvent as a continuous phase. A method for dewatering sludge by mixing a water-in-oil emulsion as a phase and an acid in dissolved water, adding the resulting mixed liquid to sludge to form coagulated flocs, and then dewatering the sludge. A sludge dewatering method, characterized in that the proportion of acid used is at least twice the equivalent of the M-alkalinity (calculated as CaCO_3) of the dissolved water. (2) A sludge dehydrating agent used in the sludge dewatering method according to claim 1, which is an oil containing a cationic polymer flocculant in a dispersed aqueous phase and an organic solvent as a continuous phase. A sludge dewatering agent made by mixing a water-in-oil emulsion and a water-in-oil emulsion having an anionic polymer flocculant in the dispersed water phase and an organic solvent in the continuous phase.