JPH0938700A - Treatment of organic sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve treating efficiency of organic sludge and to simultaneously simplify the treating operation and treating equipment by developing such a flocculant that a superior flocculation work is exhibited for various organic sludge-containing waste water liquid at a relatively small addition quantity to give a dehydrated cake being low in water content and having excellent peelability from filter cloth and a screen. SOLUTION: A polyalkylene imine type high molecular flocculant having a molecular weight of one million to eight million and a cation type high molecular flocculant having quartenary amino groups are jointly used as the flocculant in the treatment of the organic sludge using a high molecular flocculant.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sewage palm urine treatment plant,
The present invention relates to an improved treatment method capable of efficiently aggregating organic sludge generated from organic industrial wastewater and the like and performing treatment such as dehydration more easily.

[0002]

2. Description of the Related Art As a method for treating organic sludge produced from a sewage sewage treatment plant, an organic industrial wastewater, etc., a high-molecular flocculant is added to and mixed with a sludge-containing liquid, which is then subjected to a belt press, A method of dehydration treatment using a centrifugal dehydrator, a filter press or the like is adopted. The sludge that has been dehydrated (hereinafter, also referred to as dehydrated cake) is dumped to a landfill or incinerated.

By the way, in the dumping to the landfill site, not only the decrease of the landfill site has become a social problem in recent years, but also the dump site tends to become remoter and the transportation cost increases. On the other hand, in the incineration method, it has been pointed out that the fuel cost increases because most of the fuel is consumed for the evaporation of the water remaining in the dehydrated cake. Generally, the water content in the dehydrated cake decreases by 1%. Then, it is said that the fuel consumption can be saved by about 10%. In recent years, due to changes and diversification of the properties of the waste liquid to be treated, the number of organic sludges that are difficult to dehydrate has increased, and even from such organic sludge-containing waste liquids, organic sludge can be more efficiently agglomerated and hydrated. It is desired to develop a treatment method capable of obtaining a dehydrated cake having a low rate.

As a means for meeting such demands, much research has been conducted so far with a focus on improving the aggregating performance of an aggregating agent, such as a normal nonionic polymer aggregating agent and a cationic or anionic aggregating agent. Of course, recently, a method of using a cationic and anionic coagulant in combination (Japanese Patent Publication No. 39-17492), a method of using an inorganic coagulant such as ferric chloride (JP-A-57-162700), and high amphoteric properties Method using molecular flocculant (Japanese Patent Publication No. 56199/1993)
Etc. have also been proposed.

However, in the coagulation method in which the cationic coagulant and the anionic coagulant are used in combination, the total amount of the coagulant used is larger than that in the case of using the cationic coagulant alone, and the drug cost is more than doubled. It may increase. In addition, the coagulation method that uses both an inorganic coagulant and an organic coagulant causes not only an increase in ash content at the time of incineration but also a serious problem such as shortening the life due to the inclusion of heavy metals in the treated wastewater or the corrosion of the dehydrator. May be invited. On the other hand, in the method using the amphoteric polymer flocculant, the above-mentioned difficulties do not occur, but depending on the type of sludge, a satisfactory flocculation effect may not be exhibited, and it is difficult to obtain a stable treatment effect. .

As another improvement method, a method in which a low molecular weight amphoteric flocculant as a charge neutralizing agent for sludge and a high molecular weight cationic or amphoteric polymer flocculant are used in combination (JP-A-3-849)
Although 8) has also been proposed, this method has a drawback in economical efficiency because the amount of the coagulant used as a whole becomes extremely large although a high dehydration property is obtained. As yet another alternative,
A method in which an amphoteric polymer flocculant containing a carboxyl group and an acrylate-based cationic polymer flocculant are used in combination (Japanese Patent Application Laid-Open No. HEI-2)
, 31899), but this method has a slightly higher dehydration ability than the method of using a cationic polymer flocculant alone, and satisfies the recently required high aggregation ability and dehydration ability. Not up to.

[0007]

As described above, in the prior art, in coagulating the organic sludge, it is desired to reduce the amount of the coagulant used or the water content of the dehydrated cake. Since there is a limit to the improvement of the coagulation performance of the coagulant itself, there is no choice but to adopt a method of reducing the water content of the dehydrated cake by improving the coagulation treatment step or the subsequent dehydration treatment step or modifying the equipment. This is the actual situation, and it is inevitable that the process and equipment will be complicated. Further, in the treatment of the aggregated dehydrated cake, it is desirable to obtain an aggregated state in which the dehydrated cake can be easily peeled off from a filter cloth, a screen, etc., but it is considered that the aggregating agent has been sufficiently examined from this viewpoint. I can't say.

The present invention has been made by paying attention to such a situation, and its purpose is to exhibit an excellent coagulation action to any kind of organic sludge with a relatively small addition amount, We have developed a coagulant that gives a dehydrated cake with a low water content and good peelability from filter cloths and screens, thereby improving the treatment efficiency of organic sludge and simplifying treatment operations and facilities at the same time. It aims to establish a processing method that can be done.

[0009]

[Means for Solving the Problems] The treatment method of the present invention that has been able to solve the above-mentioned problems is that when treating organic sludge with a polymer flocculant, a polycoagulant having a molecular weight of 1 to 8,000,000 is used as a flocculant. Alkyleneimine polymer flocculant and 4
There is a gist in using a cationic polymer flocculant having a graded amino group together.

The polyalkyleneimine polymer flocculant used in the present invention has a cation equivalent value (Cv) of 0.8 to 13.0 meq / g and an anion equivalent value (Av) of 0.1 to 6. An amphoteric polymer flocculant having an amount of 0 meq / g is particularly preferable, and the amphoteric polymer flocculant is a polymer or copolymer of a polymerizable monomer essentially containing a carboxyl group-containing polymerizable monomer. It is preferable that a part of the carboxyl groups in the molecule be present as a monobasic acid addition salt of a primary to tertiary aminoalkyl ester.

Of the above polyalkyleneimine-based polymer flocculants, the repeating unit represented by the following formulas [1] and [2] is most preferably 0.0 mol of the former to 1 mol of the former.
It is an amphoteric polymer flocculant present in a ratio of 05 to 7.5 mol.

[0012]

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[0013]

Embedded image

Further, as the cationic polymer flocculant having a quaternized amino group, particularly preferable is a quaternary ammonium salt of dialkylaminoalkyl (meth) acrylate and / or dialkylaminoalkyl (meth) acrylamide. Cationic polymer flocculant containing,
Alternatively, it is a cationic polymer flocculant containing a quaternary ammonium salt of at least one amine selected from the group consisting of dimethyldiallylamine, allylamine and vinylamine.

Then, the polyalkyleneimine polymer flocculant and the cationized polymer flocculant having a quaternized amino group are used together in a weight ratio of 90:10 to 10:90. The excellent coagulation performance and dehydration performance can be exhibited more reliably.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, in the present invention, a polyalkyleneimine polymer flocculant having a molecular weight of 1 to 8,000,000 and a cationized polymer flocculant having a quaternized amino group (hereinafter referred to as 4 Amino polymer-containing cationic polymer flocculants are sometimes used together, and their flocculating effects are synergistically exerted, so that a relatively small addition amount can be stably achieved regardless of the type of organic sludge. The present invention succeeds in forming agglomerated flocs having excellent dewaterability and excellent peelability from filter cloths, screens and the like.

Specific examples of the polyalkyleneimine polymer flocculant used in the present invention will be described in detail later.
It is necessary to use one having a molecular weight in the range of 1 to 8 million. If the molecular weight is less than 1 million, it may be used in combination with a quaternary amino group-containing cationic polymer flocculant described later. However, if it is not possible to obtain the excellent aggregation effect as intended in the present invention, and if the molecular weight becomes excessively high molecular weight exceeding 8 million, the dispersibility in the liquid to be treated containing organic sludge decreases, Homogeneous flocs with excellent dehydration are less likely to be formed. The more preferable molecular weight of the polyalkyleneimine polymer flocculant is in the range of 1,000,000 to 5,000,000. The range of 1 to 8,000,000, which is the preferable molecular weight of the polyalkyleneimine-based polymer coagulant, is approximately [η] = 3.5 to 14.0 ml / g in terms of intrinsic viscosity.

Among the polyalkyleneimine polymer flocculants, the cation equivalent value (Cv) is particularly preferably 0.8 to 13.0 meq / g, and more preferably 8.0.
In the range of 12.8 meq / g and the anion equivalent value (A
v) is 0.1 to 6.0 meq / g, more preferably 0.
An amphoteric polymer flocculant having a cation equivalent value (Cv) of less than 0.8 meq / g in the range of 5 to 3.0 meq / g, the amphoteric characteristic is difficult to appear, and the sludge flocculating floc dewatering property is low. Tends to be insufficient, and conversely 13.
Even if it exceeds 0 meq / g and becomes too high, the characteristics as an amphoteric character hardly appear. Also, anion equivalent value (Av)
Is less than 0.1 meq / g, the characteristics of amphotericity are not exhibited, and when it exceeds 6.0 meq / g, the solubility in the liquid to be treated containing organic sludge is lowered and the aggregation action tends to be difficult to be effectively exhibited. It is not preferable because it exists.

As such a polyalkyleneimine-based polymer flocculant, a carboxyl group in a molecule of a polymer or copolymer of a polymerizable monomer essentially containing a carboxyl group-containing polymerizable monomer is used. Include a polymer compound in which a part of the compound exists as a monobasic acid addition salt of a primary to tertiary aminoalkyl ester, and such a polymer compound has a carboxyl group such as acrylic acid or methacrylic acid. A carboxyl group-containing polymer obtained by polymerizing or copolymerizing one or more anionic polymerizable monomers (a), or a monomer component containing a nonionic polymerizable monomer (b) together with these ( It can be obtained by reacting c) with alkyleneimine to convert the carboxyl group into an aminoalkyl ester, and then converting this to a monobasic acid addition salt.

There is no limitation on the polymerization method for producing the polyalkyleneimine type polymer coagulant, and either aqueous solution polymerization or water-in-oil emulsion polymerization may be used. In this case, the polymerization initiator is a general radical polymerization. A catalyst can be used, and the hydrophobic organic solvent or surfactant used when adopting the water-in-oil emulsion polymerization method is
Known compounds can be used in any combination and in any ratio, and preferred examples of the polymerization initiator in the case of water-in-oil emulsion polymerization include azobisisobutyronitrile and dimethyl azobisbutyrate. When the water-in-oil emulsion polymerization method is adopted, preferred hydrophobic organic solvents include alicyclic solvents such as isoparaffin and cyclohexane, and kerosene.
In the above-mentioned polymerization or copolymerization, the kind and amount of the polymerization initiator, and further the temperature, etc., should be adjusted so that the molecular weight of the finally obtained polyalkyleneimine-based polymer flocculant falls within the range of 1 to 8,000,000. It is necessary to control the polymerization conditions.

A nonionic polymerizable monomer (b) which can be copolymerized with the anionic polymerizable monomer (a) in the production of the polyalkyleneimine-based polymer flocculant.
Can be any nonionic monomer copolymerizable with the anionic polymerizable monomer (a),
For example, acrylamide, methacrylamide, N, N-
Acrylamide monomers such as dimethylacrylamide;
(Meth) acrylate-based monomers such as hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate; and acrylonitrile. These nonionic monomers (b) are used as necessary for the purpose of adjusting the molecular weight and ionic equivalent of the polyalkyleneimine-based polymer flocculant, and the amount used is too large. And the ratio of the anionic monomer (a) component in the carboxyl group-containing polymer (c) becomes insufficient, and a preferable cation equivalent value as a polyalkyleneimine-based polymer flocculant finally obtained ( Cv) and the anion equivalent value (Av) are difficult to obtain. Therefore, the copolymerization ratio of these nonionic monomers (b) is 50 mol% in the monomer component ratio in the carboxyl group-containing polymer (c). It is desirable to keep the amount below.

Further, in the present invention, as described above, the cation equivalent value (C
v) is preferably 0.8 to 13.0 meq / g and the anion equivalent value (Av) is in the range of 0.1 to 6.0 meq / g. Therefore, when producing the carboxyl group-containing polymer (c). In consideration of these points, the amounts of the anionic monomer (a) and the nonionic monomer (b) to be used should be determined, and the carboxyl group-containing polymer (c) should be used as an aminoalkyl ester. At the time of conversion, it is necessary to determine the amounts of the carboxyl group-containing polymer (c) and alkyleneimine to be used.

Examples of the alkyleneimine used for the aminoalkyl esterification include 1,2-alkyleneimine (aziridine), and among them, 1,2-propyleneimine and ethyleneimine are the most preferable in view of availability and cost. Recommended as a thing. In the aminoalkyl esterification, the molar ratio to the carboxyl group in the carboxyl group-containing polymer (c) is 1.2.
It is preferable to react twice or more times of alkyleneimine, and when the amount of alkyleneimine used is insufficient, the above-mentioned suitable cation equivalent value (Cv) and anion equivalent (Av) as the polyethyleneimine-based polymer flocculant can be obtained. It gets harder.

As the monobasic acid used for forming the acid addition salt after aminoalkyl esterification, for example, mineral acids such as hydrochloric acid and nitric acid, acetic acid and formic acid can be used. 50 to 100 mol%, more preferably 60 to 9 with respect to the added alkyleneimine.
It is particularly preferable that the repeating unit represented by the formula [1] and the formula [2] is 0.005 mol to 1 mol of the former, in the range of 5 mol%. 7.5
Mol, more preferably 0.01 to 3.0 mol, and still more preferably 0.02 to 1.0 mol in a random or block sequence, and the sequence is devised in terms of polymerization conditions and polymerization procedure. Although it can be arbitrarily changed by doing so, when the monomer components constituting the repeating unit are subjected to simultaneous copolymerization reaction, a random one is most easily obtained.

In the repeating unit represented by the above formulas [1] and [2], the lower alkyl group has a carbon number of 1 to 1.
6 represents a linear or branched alkyl group, particularly preferably a methyl group, an ethyl group or a propyl group.
Further, among the integers of 1 to 5 represented by n, the integers of 1 to 3 are preferable, and it is not necessary that all of the structural units have the same number, and those having different n numbers are usually used. Coexist. Then, after the aminoalkyl esterification of the carboxyl group in the carboxyl group-containing polymer, not all of the carboxyl groups are aminoalkylated, some remain as free carboxyl groups and show anionic character, amphoteric Acts as a polymer flocculant.

The preferred proportion of the repeating units represented by the formulas [1] and [2] is 0.005 to 7.5 moles of the latter, and more preferably 1 mole of the former.
The amount is in the range of 0.01 to 3.0 mol based on the mol, whereby the synergistic effect due to the combined use with the quaternary amino group-containing cationic polymer flocculant can be more effectively exhibited. .

Next, the quaternary amino group-containing cationic polymer flocculant used in combination with the polyalkyleneimine polymer flocculant includes dialkylaminoalkyl (meth) acrylate and dialkylaminoalkyl (meth) acrylamide. It is composed of a cationic polymer having a quaternary ammonium salt as an essential component, and a nonionic monomer may be copolymerized as another monomer component therein. Examples of the cationic monomer constituting the cationic polymer include dimethylaminoethylethyl (meth) acrylate, diethylaminoethylethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide and the like. After polymerizing more than one species, or after copolymerization with other nonionic monomers,
It can be obtained by converting the amino group of the obtained polymer or copolymer into a quaternary ammonium salt with methyl chloride, benzyl chloride or the like. At this time, as the nonionic monomer copolymerized as necessary, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N,
Non-limiting examples include N-diethyl (meth) acrylamide.

Another quaternary amino group-containing cationic polymer flocculant that can be used in the present invention is obtained by methylating an amino group in a polymer such as dimethyldiallylamine, allylamine or vinylamine with methyl chloride or the like. Examples thereof include quaternary ammonium salts. The polymer is a copolymer of nonionic monomers such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide. Of course, it does not matter even if it has been done.

The polymerization for producing the quaternary amino group-containing cationic polymer flocculant can be carried out by a known method, and the quaternary amino group-containing cationic polymer flocculant is in the form of powder. Or a liquid such as a water-in-oil emulsion.

The preferred molecular weight of the quaternary amino group-containing cationic polymer flocculant is in the range of 10,000 to 8,000,000, more preferably 1,000,000 to 6,000,000, and those having a molecular weight of 10,000 to 8,000,000 are unique. When expressed in terms of viscosity, it is approximately [η] = 0.1
It will be in the range of 5 to 14.0 ml / g. If the molecular weight is less than 10,000, equilibrium occurs in adsorption to sludge particles, and the amount of addition required to exert a sufficient cohesive action is large.
If it exceeds 0,000, it becomes difficult to uniformly disperse the coagulant in the organic sludge.

The present invention is characterized in that the above-mentioned two types of polymer flocculants are used in combination, and the reason why a remarkable effect is exhibited by the combined use is not clear, but it is a polyalkyleneimine type. It is considered that polymer flocculants, especially amphoteric polymer flocculants, have a stable structure due to the entanglement and repulsion of positive and negative ions in the molecule. It is considered that the releasability can be favorably maintained, and that the quaternary amino group-containing cationic polymer flocculant can favorably perform charge neutralization even for organic sludge having high pH and organic sludge having high alkalinity, It is considered that these functions complement each other and exert excellent aggregation ability and dehydration ability.

Typical examples of organic sludge to which the present invention is applied include sludge generated when high BOD wastewater is subjected to biological treatment and the like. For example, sludge generated in sewage and night soil treatment plants, food factories, and livestock. All including surplus sludge and first settled sludge generated by the activated sludge method treatment of wastewater and wastewater generated from plants, chemical plants, etc., or mixed raw sludge, and digested sludge generated by anaerobic digestion of wastewater and wastewater It can be applied to organic sludge.

The method of adding the above two types of coagulants to the organic sludge is not particularly limited, but one method is to add the respective coagulants at substantially the same time to act on the organic sludge, for example, to separate the coagulants separately. It is a method of dissolving in water, adding them to the organic sludge at about the same time with stirring and mixing, or premixing each coagulant and adding this to the organic sludge-containing liquid to be treated, as another method, A method of adding a quaternary amino group-containing cationic polymer flocculant to the liquid to be treated containing organic sludge and mixing them well, and then adding a polyalkyleneimine polymer flocculant to act on the organic sludge can be mentioned.
However, if the procedure of adding the polyalkyleneimine polymer flocculant first and then adding the quaternary amino group-containing cationic polymer flocculant is used, satisfactory flocculation performance may not be exhibited. It costs.

Optimum conditions for the use ratio of each coagulant and the amount added to the organic sludge differ depending on the type of the coagulant, the properties of the organic sludge and the like. Therefore, the sludge-containing liquid should be collected in a beaker or the like before practical use. It is advisable to add various amounts of each aggregating agent to this and add the same to select conditions under which the best aggregating performance and dewatering property are obtained. However, in the usual case, when the use ratio of either of the two types of coagulant is 10% by weight or less of the whole, the coagulation performance and the dehydration performance are often low. The weight ratio of the cationic polymer flocculant containing a primary amino group is 90:
From the range of 10 to 90, it is preferable to appropriately select and determine the ratio at which the best aggregation performance and dehydration performance are exhibited.

The total amount of these coagulants added to the organic sludge is not particularly limited, but the standard preferable amount is
Approximately 0.4 ~ for suspended matter (ss) components in sludge
5% by weight. When the addition amount is small, the coagulation performance is lowered, but when it is too large, the organic sludge is often redispersed and satisfactory coagulation performance cannot be obtained.

Generally, the performance of the aggregating agent is governed by ionicity, ionic equivalent value, molecular weight, chemical structure, etc., but the quaternary amino group-containing cationic polymer aggregating agent used in the present invention is a cationic group. As long as it has a quaternized amino group, the ion equivalent value and the molecular weight are not particularly limited, while the polyalkyleneimine-based polymer flocculant is
Any amphoteric polymer having a molecular weight of 1,000,000 to 8,000,000, preferably having the above-mentioned structural unit and ionic equivalent value may be used.

However, considering the aggregating property and the dehydrating property, the cationic polymer coagulant containing a quaternary amino group has a cation equivalent Cv of 1.0 meq / g or more, more preferably 2.0 m.
eq / g or more is effective, and Cv value is 1.0 me
When it is less than q / g, the aggregation performance and the dewatering performance with respect to the organic sludge tend to be slightly lowered. There is no particular upper limit to the Cv value, and a higher value tends to be more preferable, but in the usual case, the limit is inevitably about 12 meq / g due to the relationship with the molecular weight. The cation equivalent value Cv and the anion equivalent value Av of these polymer flocculants can be determined by the colloid titration method shown below.

(1) Measurement of Cation Equivalent Value I: Take 95 ml of distilled water in a beaker and add 1
After adding 5 ml of a 000 ppm solution, the pH is adjusted to 3.0 with a 1% aqueous hydrochloric acid solution or a 1% aqueous sodium hydroxide solution, and the mixture is stirred for about 1 minute. Then, add 2-3 drops of toluidine blue indicator solution and titrate with N / 400 PVSK (polyvinylsulfate potassium solution). The titration rate is 2 ml per minute, and the end point is when the test water changes from blue to magenta and is held for 10 seconds or longer. II: Calculation method Cation equivalent value (Cv) [meq / g] = (Sample titer [ml]-
Blank titration [ml]) x F / 2 x (concentration of active ingredient in sample [ppm]) The active ingredient is the solid content of the sample minus neutralizing acid, or the solid content in the case of quaternary salt. is there.

(2) Measurement of anion equivalent value I: 90 ml of distilled water was placed in a beaker, and a sample of 500 p
8 ml of a pm aqueous solution is slowly dropped, and the pH is adjusted to 11 with an N / 10 sodium hydroxide aqueous solution. Then, 10 ml of N / 200 methyl glycol chitosan reagent is added with stirring, and after stirring for 10 minutes, 2-3 drops of toluidine blue indicator is added and titrated with N / 400 PVSK.

The titration rate is 2 ml / min, and the end point is when the test water changes from blue to magenta and is held for 10 seconds or more. In addition, in the above operation, the case where no sample is added is used as a blank test. II: Preparation of 500 ppm aqueous solution of sample 0.1 g of the sample was precisely weighed and placed in an Erlenmeyer flask with a stopper,
Dissolve in 100 ml of distilled water. This 50 ml is 100 m
l Make up the volume with a measuring flask. III: Calculation method Anion equivalent value (Av) [meq / g] = (blank titration amount [ml]-
Sample titer [ml]) × F / 2 × (concentration of active ingredient in sample
[ppm])

The active ingredient is the solid content of the sample minus the neutralizing acid, or the solid content in the case of a quaternary salt. In carrying out the present invention, the above-mentioned two types of flocculants are added to the organic sludge to form flocs, and then dehydration is carried out by a known method. As the dehydrator, an ordinary sludge dehydrator can be used. For example, a belt press, a filter press, a centrifugal dehydrator, a screw press or the like can be used.

[0042]

The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and may be appropriately applied within the scope of the above and the following points. It is also possible to make changes and carry out,
All of them are included in the technical scope of the present invention.

[Synthesis Example of Polyalkyleneimine Polymer Coagulant] Water-in-oil emulsion using dimethyl azobisisobutyrate in Exol D-80 (manufactured by Exxon Chemical Co.) in the presence of acrylic acid and acrylamide as activators. Polymerize. The obtained carboxyl group-containing polymer (c) is aminoethyl esterified with ethyleneimine and then acidified with nitric acid to obtain a polyalkyleneimine polymer coagulant as a water-in-oil emulsion containing 20 wt% of an active ingredient. . Table 1 shows the composition, Cv value, Av value, and molecular weight of the obtained polyalkyleneimine polymer flocculant.

On the other hand, for comparison, it was obtained by polymerizing or copolymerizing dimethylaminoethyl methacrylate (4DAM), dimethylaminoethyl acrylate (4DAA), acrylamide (AAm) and acrylic acid (AA) by a known method. Table 1 also shows the composition and physical properties of the quaternary amino group-containing cationic polymer flocculant and the amphoteric polymer flocculant.

[0045]

[Table 1]

Example 1 pH: 5.7, SS: 2.1%, VSS: 78%, M alkalinity: 540 ppm The following experiment was carried out using a mixed sludge of the first settling sludge and excess sludge. It was Both the quaternary amino group-containing cationic polymer flocculant C-1 and the polyalkyleneimine polymer flocculant R-1 were used as 0.2 wt% aqueous solutions. The amount of each of these flocculants added is
All are shown as the weight% of sludge to SS.

After each coagulant was added simultaneously and mixed to form coagulated flocs, the mixture was stirred by a jar tester for 30 seconds, sandwiched between filter cloths for belt press and squeezed at a pressure of ² kg / cm ² for 1 minute. A dehydration test was conducted. The results are shown in Table 2. The flocs produced had a sufficient size and strength, the dehydrated cake had low tackiness, good releasability from the filter cloth, and good cake water content. .

Examples 2 to 3 The same sludge as in Example 1 was used, and the polyalkyleneimine polymer flocculants and the quaternary amino group-containing cationic polymer flocculants shown in Table 2 were used in combination. The test was conducted in the same manner as in Example 1, and good results were obtained as shown in Table 2.

Comparative Examples 1 to 5 The same sludge as in Example 1 was used, and the amphoteric polymer flocculant and the quaternary amino group-containing cationic polymer flocculant were used in the combinations shown in Table 2. The test was conducted in the same manner as in Example 1 and the results shown in Table 2 were obtained.

[0050]

[Table 2]

Comparative Example 1 is an example in which the polyalkyleneimine polymer flocculant used in Example 1 is used alone.
The peelability was normal and the dehydration performance was better than usual as compared with Example 1, but the result was clearly worse than that of Example 1.

Comparative Example 2 is the same as that used in Example 4
This is an example in which a cationic polymer flocculant containing a primary amino group was used alone, but in this case, the peelability was further deteriorated and the dehydration property was further worse than in Comparative Example 1.

In Comparative Examples 3 and 4, the 4DAM-based amphoteric polymer flocculant was used alone and the same quaternary amino group-containing cationic polymer flocculant used in Example 2 was used in combination. Although Comparative Example 4 is better than Comparative Example 3, the peelability and dehydration property are obviously poorer than those of Example 2, and Comparative Example 5 is the same as that used in Example 3.
Example in which a low-molecular-weight polyalkyleneimine-based polymer flocculant R-5 having a molecular weight of 500,000 (equivalent to [η] = 2.2 dl / g in terms of intrinsic viscosity) was used instead of -3 However, although the performance is not inferior, it is found that the amount added as the coagulant is large and the economy is poor as compared with Example 3.

[0054]

INDUSTRIAL APPLICABILITY According to the present invention, it can be expected that sludge can efficiently react up to near the charge neutralization of organic sludge by the addition of a quaternary amino group-containing cationic polymer, and polyalkyleneimine It is considered that the sludge's electric charge is neutralized by the addition of the polymer coagulant and the flocs grow greatly as aggregate flocs. By using these two coagulants together, the sewage produced from sewage, night soil treatment plants, etc. The organic sludge can be efficiently flocculated and flocculated, the water content of the dehydrated cake can be significantly reduced, and the peelability of the dehydrated cake can be significantly improved.

Claims (7)

[Claims] 1. When treating organic sludge with a polymer flocculant, a polyalkyleneimine polymer flocculant having a molecular weight of 1 to 8 million and a cation-based polymer having a quaternized amino group are used as the flocculant. A method for treating organic sludge, which is characterized by using a molecular flocculant together. 2. A polyalkyleneimine-based polymer flocculant having a cation equivalent value (Cv) of 0.8 to 13.0 meq /
The method for treating organic sludge according to claim 1, wherein an amphoteric polymer flocculant having a g and anion equivalent value (Av) of 0.1 to 6.0 meq / g is used. 3. A polyalkyleneimine polymer flocculant is a polymer derived from a polymerizable monomer essentially containing a carboxyl group-containing polymerizable monomer, wherein one of the carboxyl groups in the molecule is 3. The method for treating organic sludge according to claim 1 or 2, wherein the part is present as a monobasic acid addition salt of a primary to tertiary aminoalkyl ester. 4. A polyalkyleneimine polymer flocculant, wherein the repeating unit represented by the following formulas [1] and [2] is present in a ratio of 0.005 to 7.5 mol of the latter to 1 mol of the former. The method for treating organic sludge according to any one of claims 1 to 3. Embedded image Embedded image 5. A cationic polymer containing a quaternary ammonium salt of dialkylaminoalkyl (meth) acrylate and / or dialkylaminoalkyl (meth) acrylamide as a cationic polymer flocculant having a quaternized amino group. The method for treating organic sludge according to claim 1, wherein a flocculant is used. 6. A cationic high-molecular weight flocculant having a quaternized amino group, which comprises a quaternary ammonium salt of at least one amine selected from the group consisting of dimethyldiallylamine, allylamine and vinylamine. The method for treating organic sludge according to claim 1, wherein a molecular flocculant is used. 7. The polyalkyleneimine polymer flocculant and the cationized polymer flocculant having a quaternized amino group are used together in a weight ratio of 90:10 to 10:90. 6. The method for treating organic sludge according to any of 6.