JPH0321399A - Flocculation method of organic sludge - Google Patents

Abstract

PURPOSE:To efficiently carry out flocculation treatment of sludge and lower the water content of dewatered cake by adding a flocculant of amphoteric electrolytic polymer having a specific formula to an organic sludge after a metal salt is added to and stirred with the sludge and then dewatering the sludge. CONSTITUTION:After a metal salt, which is an inorganic flocculant, is added to and stirred with an organic sludge, an amphoteric electrolytic polymer having a formula I [n is 1-5 integer number and average value >=2; a+b+c=1; R1, R2, R3, R4, stand for H, alkyl; R5 stands for H, alkyl, omega-hydroxy-substituted alkyl; HY stands for basic acid group; and Z stands for amide groups having a formula II (R6, R7 stand for H, alkyl)] is added to the sludge to form flocs. Then, the flocs are dewatered using a dewatering machine such as a screw press-type dewatering machine.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an efficient method for dewatering inorganic and organic sludge generated from various industrial wastewaters, sewage, human waste treatment, etc. [Prior Art] Conventionally, flocculated and precipitated sludge and surplus sludge are generated in various industrial wastewater, sewage, and human waste treatments. Inorganic metal salts and organic polymer flocculants have been used as flocculants for these sludges. However, depending on the properties of the sludge, these methods cannot sufficiently reduce the water content of the dehydrated cake. In addition, recently, there has been an increase in the use of separate flow systems in sewage treatment facilities, which has resulted in an increase in organic matter in sludge, and in particular when using a belt press type dehydrator, peeling of the dewatered cake from the belt is becoming more difficult. As a result, dehydration has been stopped at a relatively high moisture content. As a sludge flocculation method to solve these problems, a method using a non-molecular flocculant and an organic polymer flocculant in combination, such as JP-A-61-216800, JP-A-61-200897, JP-A-63-1 58200 etc. have been proposed. [Problems to be solved by the invention] JP-A-59-16599, JP-A-61-216800
For example, the method of using polyferric sulfate (@Ki A2 collector) in combination with an organic polymer flocculant, and using a nonionic, anionic or cationic organic polymer flocculant alone as the organic polymer flocculant. has been described, but this method does not sufficiently reduce the moisture content of the dehydrated cake. Also, JP-A-61-200897, JP-A-61-2
0 0 8 9 No. 8 Ni! ．． A method is described in which a tmfiaf collector and an organic polymer flocculant are used together, and a cationic organic polymer flocculant and an anionic organic polymer flocculant are used simultaneously as the organic polymer flocculant. However, the removability of the dehydrated cake from the cloth is often insufficient, and it is also difficult to reduce the moisture content of the dehydrated cake. Furthermore, JP-A-63-158200 describes a method in which a non-R flocculant and an organic polymer li-collecting agent are used in combination, and an amphoteric organic polymer flocculant is used as the organic polymer flocculant. It is necessary to strictly adjust the PH value to 5-8,
The cation equivalent value, anion equivalent value, or cation equivalent jlfiff/anion equivalent value ratio of the amphoteric organic polymer 'a collector has its own limits, and a sludge flocculation method that combines flocculation performance and dewatering performance has not been found. The purpose of the present invention is to solve the above-mentioned drawbacks and provide an efficient method for collecting organic sludge. [Means for solving the problem] In the present invention, after adding a metal salt to organic sludge and stirring it, the following general formula (1) R 1 R 2 R 3 ? -CI+2-C- ] [-CIl■ -C- 1
b[-Cl2-C-]Ca C=O CO 011 2 0 (Ctl2CI1-N)nH-n(IIY) R4R5...(1> (wherein, n is an integer from 1 to 5, and n The average value of is 2 or more.The ratio of a, b, and c in the formula is a+b+c=1
, R , R , R , R4 is so 1 2
3 Each is a hydrogen atom or an alkyl group. R5 is a hydrogen atom, an alkyl group, or an alkyl group substituted with an ω-hydroxy group. HY is a monobasic acid. 2 is an amide group represented by the general formula <<2>> 1CQNR R ... (2) 67 (in the formula, R and R7 each represent a hydrogen atom or 6 represents an alkyl group), or the general formula (3) -CO2Cll- CIIOI+...(3)
I R8R9 (In the formula, R and R9 each represent a hydrogen atom or 8 represents an alkyl group.) Or a hydroxyalkyl group represented by the general formula (4
) -CN...(4) represents a nitrile group. ] This relates to a method for flocculating organic sludge, which is characterized by adding an amphoteric polymer flocculant consisting of an amphoteric polymer electrolyte shown in the following, and then dewatering. The organic sludge that is the subject of the present invention refers to sludge generated through biological treatment of high BOD wastewater, examples of which include sludge generated in sewage and human waste treatment plants, and sludge generated in the food industry and chemical industry. These include, but are not limited to. Examples of the inorganic flocculant used in the present invention include aluminum salts or iron salts as metal salts. Preferred aluminum salts include aluminum chloride, aluminum sulfate, and polyaluminum chloride (PAC). As an iron salt,
Ferric chloride, ferrous chloride, ferrous sulfate, ferric sulfate, polyferrous sulfate, etc. are suitable. Further, there is no need to particularly consider the reaction time etc. when adding the inorganic A2 collector; for example, the order of addition can be such that the inorganic flocculant is added first, and then the amphoteric polymer flocculant is added. The amphoteric polymer flocculant used in the present invention has the following general formula (1)
Ampholytic polymer electrolytes shown in can be used. R1 R2 R3 [-CIIz -C- ]a[-Cl12 -C-
16 [ -CI+2 -C- ], 11 C = Q COOH Z
iO(CH2Cll-N), H-n(IIY
)l R4 R5 ... (1) (In the formula, n = an integer from 1 to 5, and the average value of n is 2 or more. The ratio of a, b, c = 1, .R , R , R , R4 are each 1
2 3 A hydrogen atom or an alkyl group. R5 is a hydrogen atom, an alkyl group or an ω-hydroxy group; 'I1. It is a substituted alkyl group. 11Y is a monobasic acid. Z is an amide group represented by the general formula (2) -CONR R (2)67 (in the formula, R6 and R7 each represent a hydrogen atom or an alkyl group), or a general formula (3) -C0 2CH- CIIOI1...(3)R8
R9 (wherein R8 and R9 each represent a hydrogen atom or an alkyl group, or a hydroxyalkyl group represented by the general formula (4)
) -CN...(4) represents a nitrile group. ] The X value (Cv) per pl17 cation is 0.8 to 7.0 m
eq/a, anion. The equivalent value (Ay) is 0.1 to 4.
Omeq/o, Cv/Ay ratio is 1.0 to 25.0
It is characterized by being in the range of In addition, one or more anionic monomers (I) selected from acrylic acid and methacrylic acid are polymerized in water or copolymerized with nonionic monomers (II), and the vinyl carboxylic acid polymerization #% (ff) and the anionic monomer (I) at a molar ratio of 1. This is an amphoteric polymer flocculant having an aminoalkyl group and a carboxylic acid group, which is characterized by reacting an alkylene imine to a concentration of 2nol/not or more, aminoalkylating it, and then acidifying it with a monobasic acid. The amphoteric polymer flocculant in the present invention is not particularly limited; ,
The obtained vinyl carboxylic acid polymer (II) is reacted with an alkyleneidine such that the molar ratio with the anionic monomer (I) is 1.2 mol/mol or more, aminoalkylated, and then It is an amphoteric polymer electrolyte having an aminoalkyl group and a carboxyl group obtained by acidification with a basic acid, and the anionic monomer (I) is acrylic acid,
Methacrylic acid is preferred. The nonionic monomer (II) was selected in consideration of its acid dissociation properties. The acid dissociation index of acrylic acid and methacrylic acid at 25°C is 4.3 and 4.7, respectively, and acrylic acid or its salt has a pl14. ．． In water with H3 or less, the proportion of methacrylic acid or its salts as ions rapidly decreases in water with H4 or less, and I) in water with H3.5 or less, the proportion of methacrylic acid or its salts decreases rapidly. The body is also essentially in a non-dissociated state. On the other hand, in the case of anionic monomers having sulfonic acid groups etc. with a small acid dissociation index, the abundance of ionic species is large even in the low pll range of about pt+2 to 3, so even if these monomers are used, the It is not possible to obtain the superior effects of the invention. As the nonionic monomer (II), the above-mentioned monomer (I
) Any nonionic monomer copolymerizable with CH2 11R2 R1-C - can be used, for example, a vinyl type monomer having an amide group represented by the general formula (5>) can be used. C-N < II R3...(5)0 1a In formula (5), R, R2 and R3 are water or an alkyl group, specific examples include acrylamide, methacrylamide, N,N-dimethylacrylamide , N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, etc.Also, vinyl monomers having a hydroxyalkyl group represented by general formula (6) 11 R, -C -Co Cll-CI+ -011
... (6) 110 R2R3 -fi In the formula (6), R, R2 and R3 are hydrogen or an alkyl group, and specific examples include hydroxyethyl allylate, hydroxyethyl methacrylate, hydroxypropyl acrylate. , hydroxypropyl methacrylate, etc. Other examples include acrylonitrile. The nonionic monomer (II) is used for the purpose of adjusting the molecular weight and ionic equivalent of the amphoteric polymer dehydrating agent. Usually, it is preferably 50 mol% or less of the vinyl carboxylic acid polymer (III). The amphoteric polymer dehydrating agent produced by the method of the present invention has a cation equivalent value Cv of 0.8 to 7. OIleq/g, anion equivalent value ^vIfi0. 1 to 4. During the polymerization of the vinyl carboxylic acid polymer (II), the anionic monomer (I), Nonionic monomer (II
) is necessary to determine the use l. Furthermore, during aminoalkylation, it is necessary to determine the amounts of vinyl carboxylic acid polymer (I[) and alkylene imine to be used. The alkylene imines used are 1,2-alkylene imines (aziridines), of which 1,2 propylene imine and ethylene imine are particularly preferred because of their availability and relative cost. Other substituted 1,2 aziridines may be used if desired. If the cation equivalent value Cv is less than 0.8 neq/g, amphoteric characteristics will appear, which is not preferable because the dewatering property will be poor in sludge flocculation treatment and dewatering treatment, and if the cation equivalent value Cv is less than 7. If it is larger than 0 nec+/g, it is difficult for hermaphrodite characteristics to appear. Furthermore, the anion equivalent value ^V is O. When it is smaller than leq/g, amphoteric characteristics are difficult to appear, and the anion equivalent value Ay is 4. O
If it exceeds n+eq/g, the solubility in water tends to decrease, which is not preferable. If the Cv/^V value is less than 1.0 and the anion value is too large, the effect of the cationic group will be destroyed, which is not preferable.
When /Av flU exceeds 25, the proportion of anionic groups is too small and sufficient amphoteric action cannot be expected. The vinyl carboxylic acid polymer (III) can be polymerized by a conventional method using a conventional radical polymerization initiator such as an azo type or a redox type. Aminoalkylation is also carried out using known methods. When synthesizing, the Cv value is 0.
．． 8-7. 0meq/a. Av value is 0.

1-4. 0 +1eQ/Q, CV/^V ratio 1.0~
The composition amount of the monomer can be controlled to be within the range of 25.0. In addition, the intrinsic viscosity [η] value is [η] = 1.0 to 25.0 d
It is desirable to control the polymerization conditions, amount of polymerization catalyst, etc. so that the amount is J/g. In the present invention, an amphoteric organic polymer flocculant is added to form a floc, which is then dehydrated by a known method.
Examples of dehydrators include screw press type dehydrators,
Filter press type dehydrators, belt press type dehydrators, screw decanters, etc. can be used. [Examples] The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto in any way. The carboxylic acid polymer (III) was aminoethylated using ethyleneimine while taking into account the balance of cation equivalent/anion equivalent, and then acidified with nitric acid to obtain an aqueous solution containing 20% by weight of the active ingredient. The composition, cation equivalent value/anion equivalent value, and intrinsic viscosity of the combined amphoteric polymer flocculant are shown in Table 1. On the other hand, for comparison, for example, quaternized methylaminoethyl methacrylate (4-DAM) acrylamide (AA
Amphoteric polymer flocculants obtained by copolymerizing acrylic acid (AA) and acrylic acid (AA) using known methods are also shown in the same manner. Table 1 shows the composition and physical properties of the polymer. The physical properties of the quaternized homopolymer of dimethylaminoethyl methacrylate and polyethyleneimine are also shown. [Synthesis Example of Amphoteric Polymer Flocculant, etc.] Amphoteric polymer flocculant, etc., can be produced by, for example, aqueous solution polymerization of acrylic acid and acrylamide using ammonium persulfate and sodium bisulfite. Ethyleneimine, AAm; Acrylamide, M; Acrylic acid, 4-DAM; Dimethylaminoethyl methacrylate quaternized compound composition is the weight % of the monomer, the cation equivalent value is the value at -17, and the intrinsic viscosity is 30'C. Value at 1N-NaN03, R-1 -R
-3 (f) Acid neutralization is nitric acid tlN03/E1=0.
7 mol/mo/k polyethyleneimine is evomin ■p-i
ooo cday#W騨M] was used. [Examples 1 to 6, Comparative Examples 1 to 6J In the Examples and Comparative Examples, the amphoteric organic polymer flocculants shown in Table 1 were used, and the inorganic flocculants were used as a 10% by weight aqueous solution. The flocculant is 0.21! It was used as a % aqueous solution. In addition, the amounts of these flocculants added were expressed as the weight percent of aluminum or iron relative to the SS in the sludge. Mixed raw sludge from a certain sewage treatment plant (Ell+6.5, SS
2.2 t%, VSS/SS 70.4%> 1 5
Add a predetermined amount of inorganic flocculant listed in Table 2 to 0 ml, stir at 300 rtll1 for about 2 minutes, then add a predetermined amount of polymer flocculant, and stir at 200 rpm for 30 min.
Secondrffl#j! Stir to collect W. Coagulated sludge 100m
1 was poured onto a Buchner funnel lined with 100 mesh nylon cloth, and the amount of water poured after 10 seconds was measured. Next, the sludge that had been defiltered for 5 minutes was placed between P plates and dehydrated by pressing at 0.5 kg/1 for 2 minutes, and the water content of the sludge (cake) after dewatering was measured. In all cases, the flocs produced had sufficient size and strength, and the dehydrated cakes were flaky and less sticky, giving good results in terms of cake moisture content, etc. The results are shown in Table 2. For comparison, when agglomeration was performed under the same conditions in combination with a conventional drug (ampholyte) (Comparative Examples 1 and 4), in combination with cationic DAM (Comparative Examples 2 and 5), and in combination with polyethylene Table 2 also shows the combination with imine (Comparative Example 3) and the case where the amphoteric polymer flocculant was used alone (Comparative Example 6). It can be seen that aggregates were obtained, and the dehydration properties were also very good.Also, even under the same conditions, sufficiently good granular aggregates could not be obtained using a combination of chemicals or a polymer flocculant alone according to the conventional method. However, in both cases, the dehydration properties were not sufficiently good. [Effects] The flocculation method of the present invention adds a combination of a metal salt and a specific polymer electrolyte to organic sludge and granulates it. Even with sludge, granular aggregates with extremely good properties can be obtained.The granular aggregates also have excellent dewatering properties, and their water content can be greatly improved compared to conventional methods. The cation equivalent value, anion equivalent
Add 5 ml of 1% 11C1 or 1% Na0
11 to adjust the pH to 7.0 and stir for about 1 minute, then add 2 to 3 drops of toluidine blue indicator solution at N/400PV.
Titrated with SK (polyvinyl potassium sulfate solution). The titration rate was 2 ml per minute, and the color of the sample water changed from blue to reddish-purple.
The end point was when the hold was held for 0 seconds or more. Cation equivalent value (Cv) [Ileq/g] = (sample titer [
ml] 1 blank titer [ml]) x F/2x (Amount of active ingredient in sample [g]) Note that the active ingredient is the solid content of the sample excluding the neutralizing acid. (2) Anion per Jl [50ml of distilled water was placed in a beaker, and approximately 0.3g of the sample was accurately weighed and added. While stirring, titrate with N/10 NaOH solution and read the conductivity. Read the titer corresponding to the last of several inflection points (the point at which all the acid has been neutralized). Anion equivalent value (^v) [neq/a]=O. t
xFx (N/10 Appropriate amount of NaOtl [.nl]
) - (mNumber of millimoles of neutralized acid charged in the weighed sample [l'le
ql)/(Amount of active ingredient in sample [g]) (1) Dissolve 0.2 parts by weight of the sample polymer in 100 parts by volume of water and adjust to p114 with hydrochloric acid.

Collect 50 ml of this solution into a 200 ml Erlenmeyer flask with a stopper, add 50 ml of 2N-NaNO3, and stir gently to dissolve uniformly. Then from this solution,
0.02%, 0.04%, 0.06%, 0.08
% solution. Use IN-NaN03 for dilution and adjust the pH to 4. A Canon Fenske viscometer was set on a constant temperature coil adjusted to 30°C ± 0.1°C, and sample 1 was measured.
Put 0ml into the viscometer, let it flow down naturally, and measure the time required for it to pass between the upper and lower marked lines of the measuring ball. Repeat this operation 11 times at least 3 times and calculate the average value. Use is-NaN03 solution as a blank. This same operation is performed for 0.02-0.08% solutions. Calculate the reduced viscosity using the following calculation. Relative viscosity ηrel=t/to Specific viscosity ηSp= (t −to) /to = ηr
el -1 reduced viscosity ηsp/c Take each sample concentration on the horizontal axis of the graph, take the reduced viscosity on the vertical axis, plot each measured value, draw a straight line passing through each point, and calculate the value on the vertical axis when the sample concentration is O. Let be the intrinsic viscosity. to=IN − NaN03 flow time t=sample solution flow time ηrel=relative viscosity ηsp=specific viscosity C=concentration of sample solution

Claims (4)

[Claims] (1) After adding metal salts to organic sludge and stirring, the general formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(1) (In the formula, n = an integer from 1 to 5) Moreover, the average value of n is 2 or more.The ratio of a, b, and c in the formula is a+b+c=1.R_1, R_2, R_3, and R_4 are each a hydrogen atom or an alkyl group.R_5 is hydrogen It is an alkyl group substituted with an atom, an alkyl group, or an ω-hydroxy group. HY is a monobasic acid. Indicates a hydrogen atom or an alkyl group), or an amide group represented by the general formula (3) ▲Mathematical formula, chemical formula, table, etc.▼...(3) (In the formula, R_8 and R_9 each represent a hydrogen atom or represents an alkyl group) or a hydroxyalkyl group represented by the general formula (4
) -CN...(4) represents a nitrile group. ] A method for flocculating organic sludge, which comprises adding an amphoteric polymer flocculant consisting of an amphoteric polymer electrolyte represented by the formula below, and then dewatering. (2) The cation equivalent value (Cv) of the amphoteric polymer flocculant is 0
．． 8 to 7.0 meq/g, anion equivalent value (Av) is 0
．． 1 to 4.0 meq/g, Cv/Av ratio 1.0 to 2
5. The method of claim 1, wherein the polyampholyte is in the range of 5.0. (3) the amphoteric polymer flocculant polymerizes one or more anionic monomers (I) selected from acrylic acid and methacrylic acid in water, or copolymerizes with a nonionic monomer (II), The vinyl carboxylic acid polymer (III) is reacted with an alkylene imine such that the molar ratio with the anionic monomer (I) is 1.2 mol/mol or more, aminoalkylated, and then treated with a monobasic acid. The method according to claim 1 or 2, wherein the amphoteric polymer electrolyte has an aminoalkyl group and a carboxylic acid group and is produced by acidification. (4) The method according to claim 1, wherein the metal salt is an aluminum or iron salt.