JP3064878B2 - Organic sludge treatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a sewage and night soil treatment plant,
The present invention relates to an improved treatment method for efficiently coagulating organic sludge generated from organic industrial wastewater or the like and performing treatment such as dehydration more easily.

[0002]

2. Description of the Related Art As a method for treating organic sludge generated from sewage, human waste treatment plants, organic industrial wastewater, etc., a polymer-based flocculant is added to and mixed with the sludge-containing liquid, and the mixture is coagulated. A method of performing a dehydration treatment using a centrifugal dehydrator, a filter press, or the like is employed. Dewatered sludge (hereinafter sometimes referred to as dewatered cake) is dumped in landfills or incinerated.

[0003] Disposal in landfills has not only been a social problem in recent years as the number of landfills has been reduced, but also has a problem in that disposal locations tend to be further remote and transportation costs increase. On the other hand, in the incineration method, it has been pointed out that the fuel cost is increased because most of the fuel is consumed for evaporating the water remaining in the dewatered cake, and the water in the dewatered cake is generally reduced by 1%. Then, it is said that fuel consumption can be reduced by about 10%. In addition, in recent years, due to changes in properties and diversification 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, the organic sludge can be more efficiently coagulated to contain water. It is desired to develop a processing method that can obtain a dewatered cake having a low rate.

[0004] As a means for meeting such a demand, many studies have hitherto been made with a focus on improving the coagulability of the coagulant, and ordinary nonionic polymer coagulants, cationic or anionic coagulants have been developed. Of course, recently, a method using a cationic and an anionic flocculant in combination (Japanese Patent Publication No. 39-17492), a method using a coagulant with an inorganic flocculant such as ferric chloride (JP-A-57-162700), and the like. Method using molecular coagulant (Japanese Patent Publication No. 5-56199)
Etc. have also been proposed.

However, in the coagulation method using both a cationic coagulant and an anionic coagulant, the total amount of the coagulant used is larger than in the case of using the cationic coagulant alone, and the drug cost is more than doubled. May increase. In addition, the coagulation method using an inorganic coagulant and an organic coagulant not only causes an increase in ash content during incineration, but also causes serious problems such as the incorporation of heavy metals into the treated wastewater or the shortening of the service life due to the corrosion of dehydrators. May be invited. On the other hand, the method using an amphoteric polymer flocculant does not cause the above-described difficulties, but a satisfactory flocculant effect may not be exhibited depending on the type of sludge, and it is difficult to obtain a stable treatment effect. .

As another improvement method, a low molecular weight amphoteric flocculant as a sludge charge neutralizer 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 high economical efficiency because a high amount of coagulant is used as a whole although high dehydration properties can be obtained. As yet another alternative,
A method in which a carboxyl group-containing amphoteric polymer flocculant is used in combination with an acrylate cationic polymer flocculant
However, this method only slightly increases the dehydration ability as compared with the method using a cationic polymer flocculant alone, and satisfies the recently required high aggregating ability and dehydration ability. Not yet.

[0007]

As described above, in the prior art, in the case of coagulating organic sludge, it is desired to reduce the amount of coagulant used or to reduce the water content of the dewatered cake. Since there is a limit to the improvement of the coagulation performance of the coagulant itself, it is necessary to adopt a method of reducing the water content of the dewatered cake by improving the coagulation treatment step or the subsequent dehydration treatment step or remodeling the equipment. This is the actual situation, and the processing steps and equipment have to be complicated. In the treatment of the agglomerated dewatered cake, it is desirable to obtain an agglomerated state such that the dewatered cake can be easily peeled off from a filter cloth, a screen, or the like, but it is considered that a coagulant has been sufficiently studied from such a viewpoint. I can't say.

The present invention has been made in view of such circumstances, and an object thereof is to exhibit an excellent coagulation action with a relatively small addition amount to any kind of organic sludge, Developed a flocculant that gives a dewatered cake with low water content and good removability from the filter cloth and screen, thereby simultaneously improving the efficiency of organic sludge treatment and simplifying the treatment operation and treatment equipment. The aim is to establish a treatment method that can be performed.

[0009]

Means for Solving the Problems The treatment method of the present invention, which can solve the above-mentioned problems, relates to a method of treating organic sludge with a polymer flocculant. Alkyleneimine polymer flocculant and 4
The point is that a cationic polymer flocculant having a graded amino group is used in combination.

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. Particularly preferred is an amphoteric polymer flocculant of 0 meq / g. 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 group in the molecule is present as a monobasic acid addition salt of a primary to tertiary aminoalkyl ester.

Among the above-mentioned polyalkyleneimine-based polymer flocculants, particularly preferred are the repeating units represented by the following formulas (1) and (2):
It is an amphoteric polymer flocculant present in a ratio of 0.05 to 7.5 moles.

[0012]

Embedded image

[0013]

Embedded image

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

The above polyalkyleneimine polymer flocculant and the cationic polymer flocculant having a quaternized amino group are used together in a weight ratio of 90:10 to 10:90, 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 polyalkylenimine polymer flocculant having a molecular weight of 1 to 8 million and a cationic polymer flocculant having a quaternized amino group (hereinafter referred to as 4 Combined use of secondary amino group-containing cationic polymer flocculant) and synergistically exert their flocculation action, stably with a relatively small amount of addition regardless of the type of organic sludge. In addition to exhibiting excellent dewatering properties, it has succeeded in forming a flocculated floc having excellent releasability from a filter cloth, a screen or the like.

Specific examples of the polyalkyleneimine polymer flocculant used in the present invention will be described later in detail.
It is necessary to use those having a molecular weight in the range of 1,000,000 to 8,000,000, and if the molecular weight is less than 1,000,000, regardless of the combined use with a quaternary amino group-containing cationic polymer flocculant described later. When the excellent coagulation effect as intended in the present invention cannot be obtained, and when the molecular weight is too high, the dispersibility in the liquid to be treated containing organic sludge is reduced, It is difficult to form a homogeneous and excellent dewatering floc. The more preferable molecular weight of the polyalkyleneimine-based polymer flocculant is in the range of 1,000,000 to 5,000,000. The preferred molecular weight of the polyalkyleneimine-based polymer flocculant in the range of 1 to 8,000,000 is generally in the range of [η] = 3.5 to 14.0 ml / g in terms of intrinsic viscosity.

Among the polyalkyleneimine-based polymer flocculants, particularly preferred are those having a cation equivalent value (Cv) of 0.8 to 13.0 meq / g, and more preferably 8.0 to 13.0 meq / g.
In the range of 12.8 meq / g and an anion equivalent value (A
v) is 0.1 to 6.0 meq / g, more preferably 0.1 to 6.0 meq / g.
If the amphoteric polymer flocculant is in the range of 5 to 3.0 meq / g and has a cation equivalent value (Cv) of less than 0.8 meq / g, the characteristics as amphoteric hardly appear and the dewatering property of the sludge flocculated floc Tend to be insufficient, and conversely 13.
If it exceeds 0 meq / g and becomes too high, the characteristics as amphoteric will hardly appear. In addition, anion equivalent value (Av)
Is less than 0.1 meq / g, the amphoteric feature is not exhibited. If it exceeds 6.0 meq / g, the solubility in the organic sludge-containing liquid to be treated is reduced, and the coagulation action tends to be hardly exhibited effectively. Is not preferred.

Such a polyalkyleneimine-based polymer coagulant includes, in a polymer or copolymer of a polymerizable monomer essentially containing a carboxyl group-containing polymerizable monomer, a carboxyl group in the molecule. May be a high molecular compound present as a monobasic acid addition salt of a primary or secondary aminoalkyl ester. Such a high molecular 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 therewith ( It can be obtained by reacting c) with an alkylene imine to convert the carboxyl group into an aminoalkyl ester, and then converting this into a monobasic acid addition salt.

The polymerization method for producing the polyalkyleneimine polymer flocculant is not limited at all, and may be aqueous solution polymerization or water-in-oil emulsion polymerization, in which case the polymerization initiator is a general radical polymerization. A catalyst can be used, and a hydrophobic organic solvent or a surfactant used when a water-in-oil emulsion polymerization method is used is, for example,
Known compounds can be used in any combination and in any ratio. Preferred examples of the polymerization initiator in the case of water-in-oil emulsion polymerization include azobisisobutyronitrile and dimethyl azobisbutyrate. In addition, as a preferable hydrophobic organic solvent when the water-in-oil emulsion polymerization method is employed, for example, an alicyclic solvent such as isoparaffin or cyclohexane, or kerosene is used.
In the above polymerization or copolymerization, the type and amount of the polymerization initiator, and further the temperature, etc., so that the molecular weight of the finally obtained polyalkyleneimine polymer flocculant falls within the range of 1,000,000 to 8,000,000. It is necessary to control the polymerization conditions.

In producing the above-mentioned polyalkyleneimine polymer flocculant, a nonionic polymerizable monomer (b) copolymerizable with an anionic polymerizable monomer (a)
Can be used any nonionic monomer copolymerizable with the anionic polymerizable monomer (a),
For example, acrylamide, methacrylamide, N, N-
Acrylamide monomers such as dimethylacrylamide;
(Meth) acrylate monomers such as hydroxyethyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate; and acrylonitrile. These nonionic monomers (b) are used as needed for the purpose of adjusting the molecular weight and ion 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, so that the cation equivalent value of the finally obtained polyalkyleneimine polymer flocculant ( Cv) and the anion equivalent value (Av) are hardly obtained, so that the copolymerization ratio of these nonionic monomers (b) is 50 mol% in terms of the monomer component ratio in the carboxyl group-containing polymer (c). It is desirable to keep it below.

In the present invention, as described above, the cation equivalent value (C
v) is preferably in the range of 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, so that the carboxyl group-containing polymer (c) is produced. In consideration of these points, the amount of the anionic monomer (a) and the amount of the nonionic monomer (b) to be used should be determined. In the conversion, it is necessary to determine the amounts of the carboxyl group-containing polymer (c) and the alkyleneimine to be used.

Examples of the alkyleneimine used for the aminoalkyl esterification include 1,2-alkyleneimines (aziridines). Among them, 1,2-propyleneimine and ethyleneimine are most preferable in terms of availability and cost. Recommended as one. In the aminoalkyl esterification, the molar ratio of the carboxyl group in the carboxyl group-containing polymer (c) to the carboxyl group is 1.2.
The alkyleneimine is preferably reacted twice or more times. When the amount of the alkyleneimine used is insufficient, the above-mentioned suitable cation equivalent value (Cv) and anion equivalent (Av) as the polyethyleneimine-based polymer flocculant are obtained. It becomes difficult.

As the monobasic acid used for converting the aminoalkyl ester into an acid addition salt, for example, mineral acids such as hydrochloric acid and nitric acid, acetic acid, formic acid and the like can be used. , 50 to 100 mol%, more preferably 60 to 9 mol% based on the added alkyleneimine.
Among the above polyalkyleneimine-based polymer flocculants having a range of 5 mol%, particularly preferred is the repeating unit represented by the formulas [1] and [2], wherein the repeating unit represented by the formula [1] and the formula [2] is 0.005 to the mole of the former. 7.5
Moles, more preferably 0.01 to 3.0 moles, still more preferably 0.02 to 1.0 moles in a random or block arrangement, and the arrangement is devised by polymerization conditions and polymerization procedures. Can be changed arbitrarily, but when a monomer component constituting the above repeating unit is subjected to a simultaneous copolymerization reaction, a random one is most easily obtained.

In the repeating unit represented by the formulas [1] and [2], the lower alkyl group has 1 to 1 carbon atoms.
6 represents a linear or branched alkyl group, and particularly preferable are a methyl group, an ethyl group, and a propyl group.
Further, among the integers 1 to 5 represented by n, preferred are integers 1 to 3, which are not necessarily all the same in the structural unit, but usually have different n numbers. Coexist. After the carboxyl group in the carboxyl group-containing polymer is aminoalkyl-esterified, not all of the carboxyl groups are aminoalkylated, but some remain as free carboxyl groups and exhibit anionic properties. Acts as a polymeric flocculant.

The preferred proportion of the repeating units represented by the formulas [1] and [2] is 0.005 to 7.5 mol, more preferably 1 mol, per 1 mol of the former.
It is in the range of 0.01 to 3.0 moles with respect to the mole, whereby the synergistic effect of the combined use with the quaternary amino group-containing cationic polymer coagulant can be more effectively exerted. .

Next, the quaternary amino group-containing cationic polymer coagulant used in combination with the polyalkyleneimine polymer coagulant includes dialkylaminoalkyl (meth) acrylate and dialkylaminoalkyl (meth) acrylamide. It is made of a cationic polymer containing a quaternary ammonium salt as an essential component, and may be a nonionic monomer copolymerized as another monomer component. Examples of the cationic monomer constituting the cationic polymer include dimethylaminoethylethyl (meth) acrylate, diethylaminoethylethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide and the like. After polymerizing the seeds or more, or copolymerizing with other nonionic monomers,
It is 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, the nonionic monomers copolymerized as required include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N,
Non-limiting examples include N-diethyl (meth) acrylamide.

Another cationic polymer flocculant containing a quaternary amino group 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 of the polymer include nonionic monomers such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, and N, N-diethyl (meth) acrylamide. Of course, it does not matter.

The polymerization for producing the above quaternary amino group-containing cationic polymer flocculant can be carried out by a known method. 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 specific. When expressed in terms of viscosity, approximately [η] = 0.1
It will be in the range of 5-14.0 ml / g. When the molecular weight is less than 10,000, an equilibrium is generated in adsorption to the sludge particles, and the amount of addition necessary for exhibiting a sufficient coagulation action becomes large.
If it exceeds 10,000, it is difficult to uniformly disperse the flocculant in the organic sludge.

The present invention is characterized in that the above two kinds of polymer flocculants are used in combination, and it is not clear why the remarkable effect is exhibited by the combination of these two kinds. Polymer flocculants, especially amphoteric polymer flocculants, are considered to have a stable structure due to the entanglement and repulsion of positive and negative ions in the molecule. It is conceivable that the peelability can be favorably maintained, and that the quaternary amino group-containing cationic polymer flocculant can favorably neutralize the charge even for organic sludge having a high pH or high alkalinity, It is considered that these functions are complemented by each other and exhibit excellent coagulation ability and dehydration ability.

Representative examples of the 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 a sewage / sewage treatment plant, a food factory, livestock farming, and the like. Including excess sludge and primary sludge generated by activated sludge treatment of wastewater and wastewater generated from plants, chemical plants, etc., or mixed raw sludge of these, as well as digested sludge generated by anaerobic digestion of wastewater and wastewater It can be applied to organic sludge.

The method for adding the two types of flocculants to the organic sludge is not particularly limited. One method is to add the respective flocculants almost simultaneously and to act on the organic sludge, for example, to separate each flocculant separately. It is a method of dissolving in water, adding these to the organic sludge almost simultaneously and stirring and mixing, or mixing each coagulant in advance and adding this to the organic sludge-containing liquid to be treated, as another method, First, a method of adding a quaternary amino group-containing cationic polymer flocculant to an organic sludge-containing liquid to be treated and mixing well, and then adding a polyalkyleneimine-based polymer flocculant to act on the organic sludge may be mentioned.
However, if a procedure in which a polyalkyleneimine-based polymer flocculant is added first and then a quaternary amino group-containing cationic polymer flocculant is adopted is employed, satisfactory flocculation performance may not be exhibited. It costs.

The optimum conditions for the use ratio of each flocculant and the amount added to the organic sludge vary depending on the type of the flocculant, the properties of the organic sludge, and the like. Therefore, the sludge-containing liquid is collected in a beaker or the like before being put into practical use. It is preferable to add various amounts of each coagulant to the mixture and to select conditions under which the best coagulation performance and dehydration properties can be obtained. However, in a normal case, when the use ratio of either of the two types of coagulants is 10% by weight or less, the coagulation performance and dehydration performance often decrease, so that the polyalkyleneimine-based polymer coagulant and 4 The amino-group-containing cationic polymer flocculant has a weight ratio of 90:
From the range of 10 to 10 to 90, the ratio at which the best coagulation performance and dehydration performance are exhibited may be appropriately selected and determined.

The total amount of the coagulant added to the organic sludge is not particularly limited.
Approximately 0.4 to the suspended solid (ss) component in sludge
5% by weight. When the addition amount is small, the coagulation performance is reduced, but when it is too large, the organic sludge is often re-dispersed and satisfactory coagulation performance cannot be obtained.

In general, the performance of the flocculant is governed by ionicity, ion equivalent value, molecular weight, chemical structure and the like. The quaternary amino group-containing cationic polymer flocculant used in the present invention is a cationic group flocculant. As long as it has a quaternized amino group, the ion equivalent value and 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 ion equivalent value may be used.

However, considering the cohesiveness and dehydration, the quaternary amino group-containing cationic polymer coagulant has a cation equivalent value Cv of 1.0 meq / g or more, more preferably 2.0 meq / g.
eq / g or more are effective, and Cv value is 1.0me
When it is less than q / g, the flocculation performance and the dewatering performance on organic sludge tend to slightly decrease. There is no particular upper limit of the Cv value, and a higher value tends to be more preferable. However, in the normal case, the limit is inevitably about 12 meq / g from the relation 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 described below.

(1) Measurement of cation equivalent value I: 95 ml of distilled water was placed in a beaker, and 1 part of the sample was added thereto.
After adding 5 ml of the 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. Next, 2-3 drops of a toluidine blue indicator solution are added and titrated with N / 400 PVSK (polyvinyl potassium sulfate solution). The titration speed is 2 ml per minute, and the end point is the time point at which the sample changes color from blue to magenta and is held for 10 seconds or more. II: Calculation method Cation equivalent value (Cv) [meq / g] = (sample titer [ml]-
Blank titer [ml]) x F / 2 x (concentration of active ingredient in sample [ppm]) The active ingredient is the solid content of the sample excluding the neutralizing acid, or the solid content in the case of a quaternary salt. is there.

(2) Measurement of anion equivalent value I: 90 ml of distilled water was placed in a beaker, and 500 p
8 ml of a pm aqueous solution is slowly dropped, and the pH is adjusted to 11 with an N / 10 aqueous sodium hydroxide solution. Next, 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 speed is 2 ml / min, and the time when the sample changes color from blue to magenta and is maintained for 10 seconds or more is defined as the end point. In the above operation, a case where no sample is added is defined as a blank test. II: Preparation of 500 ppm aqueous solution of sample 0.1 g of sample was precisely weighed and placed in a stoppered Erlenmeyer flask.
Dissolve in 100 ml of distilled water. This 50ml is 100m
Make up in a 1 volumetric flask. III: Calculation method Anion equivalent value (Av) [meq / g] = (blank titration [ml]-
Sample titer [ml]) x F / 2 x (concentration of active ingredient in sample)
[ppm])

The active ingredient is a component obtained by removing the neutralizing acid from the solid content of the sample, or a 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 organic sludge to form flocs, and then dewatered by a known method.A dewatering machine can use a normal sludge dewatering machine. For example, a belt press, a filter press, a centrifugal dehydrator, a screw press and the like can be used.

[0042]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and may be appropriately determined within a range that can conform to the purpose of the preceding and the following. Changes can be made and implemented.
They are all included in the technical scope of the present invention.

[Synthesis example of polyalkyleneimine polymer flocculant] 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 Perform polymerization. The obtained carboxyl group-containing polymer (c) is aminoethyl-esterified with ethyleneimine and then acidified with nitric acid to obtain a polyalkyleneimine-based polymer flocculant as a water-in-oil emulsion having an active ingredient of 20 wt%. . Table 1 shows the composition, Cv value, Av value, and molecular weight of the obtained polyalkyleneimine-based 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 The following experiment was carried out using mixed sludge of primary sewage sludge and excess sludge of pH: 5.7, SS: 2.1%, VSS: 78%, M alkalinity: 540 ppm. Was. Both the quaternary amino group-containing cationic polymer flocculant C-1 and the polyalkylenimine polymer flocculant R-1 were used as 0.2% by weight aqueous solutions. The amount of each of these coagulants is
In each case, the sludge was shown as a percentage by weight based on the SS.

Each flocculant was simultaneously added and mixed to form flocculated floc, stirred for 30 seconds by a jar tester, sandwiched between filter cloths for belt press, and squeezed at a pressure of ² kg / cm ² for 1 minute. A dehydration test was performed. The results are as shown in Table 2. The generated floc had a sufficient size and strength. The dehydrated cake had low tackiness, good releasability from the filter cloth, and good cake moisture content. .

Examples 2-3 Using the same sludge as in Example 1, a polyalkyleneimine polymer flocculant and a quaternary amino group-containing cationic polymer flocculant were used in combination with those shown in Table 2. The test was performed 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 an amphoteric polymer flocculant and a quaternary amino group-containing cationic polymer flocculant were used in combination in Table 2. The test was performed 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 was used alone.
The releasability was about the same as in Example 1, and the dewatering performance was better than usual. However, the result was clearly worse than in Example 1.

Comparative Example 2 is the same as Comparative Example 2 used in Example 2.
This is an example in which a quaternary amino group-containing cationic polymer flocculant was used alone. In this case, the releasability was further deteriorated and the dewaterability was further worse than in Comparative Example 1.

In Comparative Examples 3 and 4, the case where the 4DAM type amphoteric polymer flocculant was used alone and the case where the same quaternary amino group-containing cationic polymer flocculant as used in Example 2 were used in combination Although Comparative Example 4 was better than Comparative Example 3, the peelability and dehydration properties were clearly worse than Example 2, and Comparative Example 5 was the same as Comparative Example 4.
Example in which a low molecular weight polyalkyleneimine polymer flocculant R-5 having a molecular weight of 500,000 (equivalent to approximately [η] = 2.2 dl / g in terms of intrinsic viscosity) is used in place of -3 However, although the performance is not inferior, the amount of the coagulant added is larger than that in Example 3, and it is inferior in economy.

[0054]

According to the present invention, it can be expected that sludge can be efficiently reacted to near the charge neutralization of organic sludge by the addition of a quaternary amino group-containing cationic polymer. It is considered that the addition of a polymer-based flocculant neutralizes the charge of the sludge and the flocs grow large as aggregate flocs. By using these two flocculants together, the sewage generated from sewage, human waste treatment plants, etc. In addition to efficiently coagulating the organic sludge into flocs, the water content of the dewatered cake can be significantly reduced, and the removability of the dewatered cake can be greatly improved.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-31899 (JP, A) JP-A-3-8498 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 11/00-11/20 B01D 21/01 C02F 1/52-1/56

Claims (7)

(57) [Claims] In the treatment of organic sludge with a polymer flocculant, a polyalkyleneimine polymer flocculant having a molecular weight of 1,000,000 to 8,000,000 and a cationic high-molecular compound having a quaternized amino group are used as a flocculant. A method for treating organic sludge, comprising using a molecular coagulant in combination. 2. A polyalkyleneimine polymer flocculant having a cation equivalent value (Cv) of 0.8 to 13.0 meq /.
2. The method for treating organic sludge according to claim 1, wherein an amphoteric polymer flocculant having an anion equivalent value (Av) of 0.1 to 6.0 meq / g is used. 3. The polyalkyleneimine-based polymer coagulant is a polymer derived from a polymerizable monomer essentially containing a carboxyl group-containing polymerizable monomer, and one of the carboxyl groups in the molecule. 3. The method for treating organic sludge according to claim 1, 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 units represented by the following formulas [1] and [2] are present in a ratio of 0.005 to 7.5 mol per mol of the former. The method for treating organic sludge according to claim 1. 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 any one of claims 1 to 4, wherein a coagulant is used. 6. A cationic polymer containing at least one quaternary ammonium salt of an amine selected from the group consisting of dimethyldiallylamine, allylamine and vinylamine as a cationic polymer flocculant having a quaternized amino group. The method for treating organic sludge according to any one of claims 1 to 4, wherein a molecular coagulant is used. 7. The polyalkyleneimine polymer flocculant and a cationic polymer flocculant having a quaternized amino group are used together in a weight ratio of 90:10 to 10:90. 7. The method for treating organic sludge according to any one of 6.