JPH0819796A - Dehydration of sludge - Google Patents

Abstract

PURPOSE:To flocculate and dehydrate sludge advanced in spoilage by adding a cationic vinyl polymer which is obtained by adding a polyfunctional monomer to all of monomers within a specific range and polymerizing the resulting monomer compsn. to sludge whose acidity becomes a specific value or more by the advance of spoilage. CONSTITUTION:A cationic vinyl polymer which is obtained by adding a polyfunctional monomer to all of monomers within the range of 0.0005-0.003wt.% and polymerizing the resulting monomer compsn. is added to sludge with acidity of 100mg/l. or more to treat the sludge. When the amt. of the polyfunctional monomer is below 0.0005wt.%, only the effect of the same degree as a polymeric flocculant is obtained and, when the amt. of the polyfunctional monomer exceeds 0.003wt.%, the addition amt. to sludge becomes excessive. The cation polymerization degree of the cationic vinyl polymer to be used is 1meq/g or more, pref., 1.5meq/g or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of aggregating and dehydrating sludge such as sewage which has been spoiled.

[0002]

2. Description of the Related Art As sludge in a sewage treatment plant advances in spoilage, acidity increases, pH also decreases, and cohesion generally deteriorates (Toshiji Fuchigami 28th Sewer Research Conference 560-56
2. Hiroaki Shimabukuro 28th Sewer Research Presentation 563-56
5).

The cause of this is not clear, but it is considered that one factor is that coarse suspended matter in the sludge is reduced by the decomposition of the sludge. No coagulant effective against such sludge has been reported.

[0004]

[Problems to be Solved by the Invention] Sludge rotting in the concentration tank of the first settled sludge in a sewage treatment plant or the like, or rotting over time in the collection pipe of sewage causes deterioration of the sedimentation property and causes sludge / water treatment It has a great influence and generally tends to deteriorate the aggregation / dehydration treatment.

This is because coarse suspended matter is caused by microorganisms in sludge,
It is thought to be due to decomposition into acetic acid, propionic acid, butyric acid, etc.

The present inventors have studied the dehydration property depending on the amount of acid (acidity) produced by the decomposition of coarse suspended matter which progresses during sludge rotting, for the purpose of solving the problem of deterioration of dehydration property. The present invention has been reached.

[0007]

The present invention provides a polyfunctional monomer in an amount of 0.0005 wt% to 0.0
The polymer added and polymerized in the range of 03 wt% has an acidity of 1
This is a sludge dewatering method in which the sludge is added to 00 mg / l or more and treated.

[0008]

[Function] Sludge, which has deteriorated due to deterioration and increased acidity, has a small amount of fibers and loses the core of coagulation, which is considered to be one of the causes of poor coagulation in ordinary polymers. It has not been done.

Surprisingly, however, the polymers described in this invention form sufficient flocs for the dehydration process.

The present invention will be described in detail below.

As the cationic vinyl polymer used in the present invention, one or two nonionic vinyl monomers are used.
Copolymers obtained by polymerizing one or more and one or more cationic vinyl monomers with one or more polyfunctional monomers, and a cationic vinyl monomer 1.
There are copolymers obtained by polymerizing one or more polyfunctional monomers by adding one or more polyfunctional monomers.

Further, one or more kinds of nonionic monomers are added to one or more kinds of polyfunctional monomers to form a copolymer obtained by polymerization, and then the functional groups are modified. A method of finally using a cationic polymer may be used.

For example, a method in which methylenebisacrylamide is added in advance to polymerize acrylamide to form polyacrylamide, which is then converted into a cationic polymer by a Mannich reaction, a Hoffmann decomposition reaction, and the like are included.

The vinyl monomer used in the present invention is (a) nonionic, (b) cationic and water-soluble.

A specific example is as follows. (A) Nonionic vinyl monomer (meth) acrylamide, vinyl methyl ether, vinyl ethyl ether, etc.

(B) Cationic vinyl monomer The following (1-A), (2-A), (3-A), (4
-A) selected from the group.

(1-A) Quaternary nitrogen-containing (meth) acrylate [(meth) acrylate refers to acrylate or methacrylate. The same applies below. ]

(I) (meth) acryloyloxyalkyltrialkylammonium salt such as 2- (meth) acryloyloxyethyltrimethylammonium chloride,
2- (meth) acryloyloxyethyltrimethylammonium methosulfate, 2- (meth) acryloyloxyethyltriethylammonium ethosulfate, 3
-(Meth) acryloyloxypropyldimethylethylammonium methosulfate and the like.

(Ii) (meth) acryloyloxyhydroxyalkyltrialkylammonium salt, eg 3-
Methacryloyloxy-2-hydroxypropyltrimethylammonium chloride, 3-methacryloyloxy-2
-Hydroxypropylmethyldiethylammonium chloride, 3-methacryloyloxy-2-hydroxypropyltrimethylammonium methosulfate and the like.

(2-A) Salt of tertiary nitrogen-containing (meth) acrylate and acid

(I) Dialkylaminoalkyl (meth)
Acrylate salts such as 2-dimethylaminoethyl (meth) acrylate sulfate and 2-diethylaminoethyl (meth) acrylate hydrochloride.

(Ii) Dialkylaminohydroxyalkyl (meth) acrylate salts such as 3-dimethylamino-2-hydroxypropyl (meth) acrylate hydrochloride, 3-diethylamino-2-hydroxypropyl (meth) acrylate sulfate and the like.

(3-A) quaternary nitrogen-containing (meth) acrylamide

(I) (Meth) acrylamidoalkyltrialkylammonium salt such as 3-acrylamidopropyltrimethylammonium chloride, 2- (meth) acryloylaminoethyltrimethylammonium methosulfate.

(Ii) (meth) acrylamidohydroxyalkyltrialkylammonium salt, eg 3-
(Meth) acryloylamino-2-hydroxypropyltrimethylammonium chloride, 3- (meth) acryloylaminoethyltrimethylammonium methosulfate and the like.

(4-A) Salt of tertiary nitrogen-containing (meth) acrylamide and acid

(I) Dialkylaminoalkyl (meth)
Acrylamide salts such as 2-dimethylaminoethyl (meth) acrylamide hydrochloride and 2-diethylaminopropyl (meth) acrylamide sulfate.

(Ii) Dialkylaminohydroxyalkyl (meth) acrylamide salts such as 3-dimethylamino-2-hydroxypropyl (meth) acrylamide acetate, 3-diethylamino-2-hydroxypropyl (meth) acrylamide sulfate and the like.

As the polyfunctional monomer, N,
N'-methylenebisacrylamide, N, N'-methylenebismethacryamide, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, divinyl compound such as divinylbenzene, vinyl methylol compound such as methylol methacrylamide , Vinyl aldehyde compounds such as acrolein, and vinyl compounds such as methyl acrylamide glycolate methyl ether.

The polyfunctional monomer of the polymer used in the present invention is 0.000 based on the total amount of the water-soluble vinyl monomer.
It is a mixture of 5 to 0.003 wt% and copolymerization.

If the amount of the polyfunctional monomer is less than 0.0005 wt%, only the effect equivalent to that of the commonly used polymer flocculant can be obtained, and if it exceeds 0.003 wt%, the amount added to sludge becomes too large. The effect cannot be recognized within a realistic range of addition amount.

The cationic degree of the cationic vinyl polymer used in the present invention (cationic polymer flocculant physical property display method and analytical method-3, Polymer Coagulant Industry Association) is 1 meq.
/ G or more, preferably 1.5 meq / g or more is particularly effective.

Particularly, the acidity of sludge of 100 mg / l or more is effective in carrying out the method of the present invention. 10
If it is 0 mg / l or less, it can be treated with a usual drug or a flocculant in many cases, but if it is 100 mg / l or more, dehydration becomes very difficult as described above. It will be possible.

The acidity is measured by the total acidity measuring method described in Section 15 of the sewer test method.

The polymer used in the present invention can be copolymerized by a commonly used known polymerization method.

Particularly preferred is a method of copolymerizing the water-soluble vinyl monomer and a small amount of a polyfunctional monomer in a hydrophobic surfactant and an organic solvent.

Further, a chain transfer agent, a chelating agent or the like can be used if necessary. Further, the polyfunctional monomer may be added before, during, or after the polymerization.

For example, an aqueous solution containing a water-soluble vinyl monomer and a polyfunctional monomer and an organic dispersion medium containing a hydrophobic surfactant having an HLB of 3 to 6 are mixed and emulsified, and then a radical polymerization catalyst is present. There is a method of producing a water-in-oil type cationic polymer emulsion by polymerizing at a temperature of 30 to 80 ° C. (Japanese Patent Application No. 61-236250).

To this water-in-oil emulsion, a hydrophilic surfactant is added and mixed with water, and the emulsion is converted into an oil-in-water emulsion for use.

The method for obtaining the cationic polymer of the present invention is as follows:
A method in which a cationic polymer is finally obtained by modifying the functional group may be used.

For example, a method in which acrylamide is preliminarily polymerized to form polyacrylamide, which is then converted into a cationic polymer by a Mannich reaction, a Hoffmann decomposition reaction, or the like is included.

The polymer used in the present invention may be in the form of powder or liquid such as emulsion and suspension, but emulsion having good water dispersibility is preferable.

Next, such a polymer was added with an acidity of 100 mg /
When added to sludge containing 1 or more and stirred and mixed, a firm and hard floc is obtained.

The method of adding the polymer to the sludge, stirring, and mixing is not limited because it varies depending on the condition of the sludge to be treated. 0.1 wt% or more and 5 wt% or less, preferably about 2 to 0.3 wt% of a polymer active ingredient is added to a product (according to the sewer test method), and rapid stirring is performed for a short time to form flocs, which are dehydrated. The method of doing is mentioned.

Hereinafter, the present invention will be described more specifically with reference to examples.

[0046]

Examples and Comparative Examples 300.0 g of dimethylaminoacrylate methyl chloride quaternary compound (DMAEA), 100.0 g of acrylamide, and 0 g of methylenebisacrylamide (MBA) (Sample A, 0 wt).
%), 0.004 g (Sample B, 0.001 w
t%), 0.01 g (Sample C, 0.0025)
wt%), 0.02 g (Sample D, 0.005
wt%) was dissolved in 307 g of distilled water to prepare an HLB solution.
15.4 g of 4.2 nonionic surfactant was poured into 204.7 g of paraffin oil and emulsified with a homogenizer.

This was degassed with nitrogen gas, and a water-soluble azo catalyst was added to polymerize it.

240.0 g of methyl chloride quaternary product of dimethylamino acrylate, and acrylamide 160.0
g, and 0 g of methylenebisacrylamide (Sample
eE, 0 wt%), 0.004 g (Sample F,
0.001 wt%), 0.01 g (Sample G,
0.0025 wt%), 0.02 g (SampleH,
An aqueous solution of 0.005 wt%) dissolved in 307 g of distilled water was poured into 204.7 g of paraffin oil, and 15.4 g of a nonionic surfactant having HLB 4.2 was added to the mixture to emulsify the mixture.

This was degassed with nitrogen gas, and a water-soluble azo catalyst was added to polymerize it.

270.0 g of methyl chloride quaternary product of dimethylamino acrylate and 130.0 of acrylamide
g, and 0 g of methylenebisacrylamide (Sample
eI, 0 wt%), 0.004 g (Sample J,
0.001 wt%), 0.01 g (Sample K,
0.0025 wt%), 0.02 g (SampleL,
An aqueous solution of 0.005 wt%) dissolved in 307 g of distilled water was poured into 204.7 g of paraffin oil, and 15.4 g of a nonionic surfactant having HLB 4.2 was added to the mixture to emulsify the mixture.

This was degassed with nitrogen gas, and a water-soluble azo catalyst was added to polymerize it.

These polymers were collected from a sewage treatment plant and putrid sludge with an acidity of 112 mg / l (TS (evaporation residue)
2.01%, SS (suspended matter) 1.96%)
After stirring at 1000 rpm for 30 seconds with the ST mixer,
Flock size standard chart Visual comparison, 60m
The amount of drainage was measured 10 seconds after pouring on the screen of esh.

Further, the sludge remaining on the screen was dehydrated by a centrifuge tube type centrifugal separator at 2000 rpm for 5 minutes to measure the water content. The results are shown in Table 1.

From Table 1, according to the method of the present invention, sludge can be efficiently dehydrated. Further, as a result of conducting a test using polyethylene glycol diacrylate instead of methylenebisacrylamide added at the time of the above-mentioned polymerization and using it in the above sludge, the same effect was obtained.

The above-mentioned polymer was collected from a wastewater treatment plant of a public use facility, and the septic sludge (TS having an acidity of 320 mg / l (TS
(4.64%, SS 4.56%) and stirred with a CST mixer at 1000 rpm for 30 seconds, and then visually compared to determine the floc size standard chart, and then poured on a screen of 60 mesh and the amount of drainage after 10 seconds was measured. .

Further, the sludge remaining on the screen was dehydrated with a centrifuge tube type centrifugal separator at 2000 rpm for 5 minutes to measure the water content. Table 2 shows the results.

From Table 2, according to the method of the present invention, sludge can be efficiently dehydrated.

The above-mentioned polymer, powdery dimethylaminoethyl methacrylate methyl chloride quaternary homopolymer (Sample M) produced by a known method, and dimethylaminoethyl methacrylate methyl chloride quaternary-acrylamide ( 50/50 mol%) copolymer (S
sludge (TS 3.84%, SS 2.6) with an acidity of 60 mg / l immediately after collecting the sample N) from the sewage treatment plant.
4%) and 30 ° C. for 2 days, spoilage progressed, and added to sludge whose acidity increased to 180 mg / l.
After stirring at 1000 rpm for 30 seconds with the ST mixer,
Flock size standard chart Visual comparison, 60m
The amount of drainage was measured 10 seconds after pouring on the screen of esh. Further, the sludge remaining on the screen was dehydrated with a centrifuge tube type centrifugal separator at 2000 rpm for 5 minutes to measure the water content. The results are shown in Table 3.

From Table 3, according to the method of the present invention, sludge can be efficiently dehydrated.

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

[Table 3]

[0063]

According to the present invention, sludge having a high acidity can be efficiently dehydrated.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masuzou Machida 1190 Kasama-cho, Sakae-ku, Yokohama Mitsui Cytec Co., Ltd. Ofuna Technical Research Institute

Claims (1)

[Claims] 1. An organic acid having a degree of acidity of 100 due to the progress of decay.
0.0005 wt% to 0.003 wt% of polyfunctional monomers in sludge that has exceeded mg / l
A sludge dewatering method, which comprises adding a cationic vinyl polymer polymerized in the range of 10% to form flocs to dehydrate.