JP5464315B2 - Sludge dewatering method - Google Patents

Description

  The present invention treats wastewater discharged from general factories such as chemical factories, semiconductor factories, food factories, paper and pulp factories, printing factories, automobile factories, biologically treated water discharged from human waste treatment plants and sewage treatment plants. The present invention also relates to an organic coagulant, a sludge dewatering composition, a wastewater treatment method, and a sludge dewatering method used in the treatment of sludge generated by the treatment.

  From the viewpoint of protecting the global environment and ensuring human health, regulations relating to wastewater treatment are becoming stricter on a global scale year by year. In particular, for river discharges and discharges into closed water areas, movements in the national and local governments have become active, such as reviewing the regulatory values for water quality management items. In addition, sludge, which is a turbid coagulated sediment, is generated in wastewater treatment, but volume reduction of sludge is required from the viewpoint of transportation costs and securing of disposal site.

  Here, for example, in the case of treatment of wastewater discharged from factories and the like, biological wastewater treatment such as activated sludge is usually performed on organic wastewater, and then turbidity removal is performed before discharge into rivers etc. For the purpose, coagulation sedimentation treatment or pressure levitation treatment is performed.

  General coagulation-precipitation and pressure flotation methods include adding inorganic flocculants such as aluminum sulfate, polyaluminum chloride, polyiron, ferric chloride, and aluminum chloride to the wastewater, and then organic polymer flocculation. The fine turbidity is agglomerated by adding the agent. Thereafter, a solid-liquid separation process is performed with a thickener or a pressure levitation device, whereby treated water with low turbidity can be obtained. The purpose of adding the inorganic flocculant is to charge the turbidity, primary aggregate the fine turbidity, and then add the high molecular weight organic polymer flocculant to further increase the primary flocculated fine flocculated floc ( Agglomerated), and easily settled in the coagulation sedimentation process, and floated easily in the pressure levitation process.

  The proper coagulation condition for the treatment with the inorganic coagulant and the organic polymer coagulant is that the pH is near neutral, so that a metal hydroxide derived from the inorganic coagulant is generated. Therefore, since the metal hydroxide also becomes sludge, the wastewater treatment method has a problem that the amount of sludge increases.

  Moreover, with recent diversification of products at factories, fluctuations in drainage components have increased and more and more non-aggregated components such as nonionic components have been included.

  Therefore, in the wastewater treatment of factory wastewater, reduction of the amount of inorganic flocculant used in recent years and stabilization and improvement of the agglomeration effect are particularly desired. Such a problem is not limited to wastewater discharged from factories, but also exists in other wastewater discharged from human waste treatment plants and sewage treatment plants.

  In response to such a request, a method of using diallyldimethylammonium chloride (DADMAC) -based polymer in combination with an inorganic flocculant (see Patent Document 1), or a method of using polyamine or a dialkylamine / epichlorohydrin condensate in combination with an inorganic flocculant ( Patent Document 2) has been proposed.

  However, the methods of Patent Documents 1 and 2 have a problem that the effect varies due to fluctuations in drainage components and a stable treatment effect cannot be obtained, and a reduction effect of the inorganic flocculant varies depending on the type of drainage.

In addition, sludge is generated during wastewater treatment as described above, and it is necessary to reduce the volume of sludge in terms of transportation costs and securing the disposal site, but in sludge volume reduction, after sludge is mechanically dehydrated. The point is how to lower the moisture content of the dehydrated cake. By reducing the moisture content, the cake weight and volume are reduced, so the problem of insufficient landfill is alleviated. In addition, when incinerating cakes, the amount of heavy oil used can be significantly reduced by lowering the moisture content, which not only reduces costs and saves energy, but also can be expected to reduce CO ₂ emissions, thus preventing global warming. Connected.

  However, diversification of products in factories is causing sludge properties that are more difficult to dehydrate than before, such as a high proportion of organic matter, and fluctuations in the sludge properties are increasing, making it difficult to perform stable sludge treatment. ing. In addition, due to diversification of eating habits, sludge discharged from human waste treatment plants and sewage treatment plants is difficult to dehydrate and has a large variation in properties, making it difficult to perform stable sludge treatment.

  Here, a high molecular weight cationic polymer is generally used for the sludge dewatering treatment, but recently it is difficult to obtain a cake with a low water content because a sufficient amount cannot be obtained. For example, a method of adding an amphoteric polymer after adding an inorganic flocculant and dewatering sludge (see Patent Document 3) and a method of using polyalkyleneimine for sludge dewatering (see Patent Document 4) have been proposed. ing.

  However, due to fluctuations in sludge properties, especially the increase in VSS (volatile floating solids) and the decrease in fiber content, it is difficult to obtain a cake with a low water content by the above method, and it is possible to apply it to recent high-efficiency dehydrators. There is a need for improvements in the sludge dewatering method, such as the difficulty in obtaining floc strength.

JP-A-6-126286 JP 2002-346572 A JP 7-256299 A JP 2003-53400 A

  In view of the circumstances described above, the present invention provides an organic coagulant that is excellent in coagulation performance and can perform wastewater treatment and sludge dewatering, and a wastewater treatment method and sludge dewatering method using the organic coagulant. With the goal.

  As a result of intensive investigations to achieve the above object, the present inventor has found that the above object is achieved by using an organic coagulant containing a cationic polymer obtained by reacting a polymer having a primary amino group or a secondary amino group with a diepoxide compound. And the present invention has been completed.

That is, the sludge dewatering method of the present invention is a cationic polymer obtained by reacting at least one of a cationic polymer flocculant and an amphoteric polymer flocculant with a polymer having a primary amino group or a secondary amino group and a diepoxide compound. After adding the organic coagulant containing the organic flocculant and the inorganic flocculant to the sludge, the sludge dewatering method, wherein the polymer having the primary amino group or the secondary amino group is polyethyleneimine or polyvinylamine, The diepoxide compound is at least one selected from the group consisting of 1,7-octadiene diepoxide, polyethylene glycol diglycidyl ether, and bisphenol A type liquid epoxy resin, and 25% by mass of a 30% by mass aqueous solution of the cationic polymer. Rotational viscosity measured with B-type viscometer at 600 ° C. and 30 rpm is 600 to A 0000mPa · s, the cationic polymer flocculating agent, a quaternary ammonium salt of dimethylaminoethyl (meth) acrylate, quaternary ammonium salts of dimethylaminopropyl (meth) acrylamide, or, cationic diallyl dimethyl ammonium chloride Cation which is a homopolymer consisting of monomers, or a copolymer of nonionic monomers copolymerizable with these cationic monomers, wherein the amphoteric polymer flocculant is a quaternary ammonium salt of dimethylaminoethyl (meth) acrylate what sex monomer and (meth) copolymer der of anionic monomer is acrylic acid, and towards the anionic monomer is characterized der Rukoto greater mole% than the cationic monomer .

The ratio of the diepoxide compound may be 0.001 to 0.1 mol% with respect to the amino group of the polymer having the primary amino group or the secondary amino group.

  According to the present invention, an organic coagulant excellent in coagulation performance can be provided by including a cationic polymer obtained by reacting a diepoxide compound with a polymer having a primary amino group or a secondary amino group. And when this organic coagulant is used in wastewater treatment, the coagulation effect is stabilized and improved, so that clear treated water can be obtained, and the amount of inorganic coagulant used can be reduced to suppress sludge generation. it can. Moreover, when this organic coagulant is used for sludge dehydration, floc strength is increased, and a cake having a low water content can be obtained. Furthermore, the mud dewatering composition containing the organic coagulant, the polymer flocculant, and the like can be satisfactorily sludge dewatered.

  Hereinafter, the present invention will be described in detail based on embodiments.

  The organic coagulant of the present invention contains a cationic polymer obtained by reacting a polymer having a primary amino group or a secondary amino group with a diepoxide compound.

  The polymer having a primary amino group or a secondary amino group is a polymer having a primary amino group, a polymer having a secondary amino group, a polymer having both a primary amino group and a secondary amino group, or a mixture thereof. Examples of the polymer having a primary amino group include a cationic polymer having a vinylamine structure obtained by hydrolysis of a polymer containing N-vinylformamide or N-vinylacetamide as a monomer unit, a cationic polymer having a vinylaniline unit, Examples include, but are not limited to, acrylamide Hoffman degradation products, cationic polymers having an allylamine structure, polyvinylamidine, and mixtures thereof. The polymer having a secondary amino group is not particularly limited, and may have a secondary amino group in the side chain of the polymer or in the main chain. Examples of the polymer having a secondary amino group include, but are not limited to, polyethyleneimine, cationic polymer having ethyleneimine and ethylene oxide units, and a mixture thereof.

  Examples of diepoxide compounds include 1,5-hexadiene diepoxide, 1,7-octadiene diepoxide, butadiene diepoxide, polyethylene glycol diglycidyl ether (polyethylene glycol polymerization degree: 2 to 30), and glycerin / epichlorohydrin adduct. Polyglycidyl ether, polyglycidyl ether of ethylene glycol / epichlorohydrin adduct, neopentyl glycol diglycidyl ether, trimethylolpropane polyglycidyl ether, bisphenol A type liquid epoxy resin, and mixtures thereof, but are not limited thereto. It is not something.

  The method of reacting the polymer having a primary amino group or secondary amino group and the diepoxide compound is not particularly limited, and for example, the reaction can be performed by the following method. First, the diepoxide compound is added as it is or as an acetone or alcohol solution at room temperature or lower while stirring a 5 to 50 mass% aqueous solution of the polymer having the primary amino group or the secondary amino group. And although reaction occurs even at room temperature, in order to reduce unreacted substances as much as possible, the cationic polymer can be obtained by preferably heating to 50 ° C. or higher and reacting for 2 to 3 hours.

  The addition amount of the diepoxide compound is preferably 0.001 to 0.1 mol%, more preferably 0.003 to 0.05 mol%, based on the amino group of the polymer having a primary amino group or a secondary amino group. is there. This is because the diepoxide compound is a crosslinking agent, and if it is too much, the resulting cationic polymer gels and becomes insoluble in water, and if it is too low, the effect of the crosslinked structure is difficult to appear. Excess or deficiency in the degree of crosslinking can be determined by the aqueous solution viscosity. The cationic polymer obtained in the above mol% range has a rotational viscosity of 600 to 10000 mPa · s as measured with a B-type viscometer at 25 ° C. and 30 rpm in a 30% by mass aqueous solution (evaporation residue conversion).

For example, when the polymer having a primary amino group or a secondary amino group is a polymer having a repeating unit represented by the following formula (i) and the diepoxide compound is the following formula (ii), the resulting cationic polymer The structure has a repeating unit represented by the following formula (1). In each formula, R ₁ and R ₃ are each independently a single bond, a phenylene group, a phenylene group-containing alkylene group, — (CH ₂ ) _n — or — (CH ₂ CH ₂ O) _n — (n is 1 And R ₂ represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or a benzyl group.

  Further, when the polymer having a primary amino group or a secondary amino group is a polymer having a repeating unit represented by the following formula (iii) and the diepoxide compound is the above formula (ii), the resulting cationic polymer The structure has a repeating unit represented by the following formula (2).

  As shown in the above formula, a cationic polymer obtained by reacting a polymer having a primary amino group or a secondary amino group with a diepoxide compound is such that the diepoxide compound crosslinks the polymer having the primary amino group or secondary amino group. Has the structure.

  In this way, the cationic polymer obtained by reacting a polymer having a primary amino group or a secondary amino group with a diepoxide compound has a crosslinked structure with a high cation density. Can be formed. Therefore, when the cationic polymer is used, waste water treatment and sludge dewatering treatment can be performed satisfactorily.

  Specifically, in the wastewater treatment method of the present invention, the organic coagulant, the inorganic flocculant, and the polymer flocculant of the present invention are added to the wastewater to perform solid-liquid separation treatment.

  In the wastewater treatment method of the present invention, first, the inorganic flocculant and the organic coagulant of the present invention are added to the wastewater and reacted with the turbidity contained in the wastewater.

  Examples of wastewater include wastewater discharged from general factories such as chemical factories, semiconductor factories, food factories, paper and pulp factories, printing factories, automobile factories, and biologically treated water discharged from human waste treatment plants and sewage treatment plants. However, it is not limited to these. With recent diversification of products in factories, fluctuations in drainage components have increased and more and more non-aggregated components such as nonionic components have been included. However, in the waste water treatment method of the present invention, since the predetermined organic coagulant is used, it can be treated well. The amount of the organic coagulant of the present invention is not particularly limited and may be adjusted according to the properties of the wastewater, but is about 1 to 100 mg / L (evaporation residue conversion) with respect to the wastewater.

  Examples of the inorganic flocculant include, but are not limited to, a sulfate band, polyaluminum chloride, aluminum chloride, ferric chloride, ferrous sulfate, and a mixture thereof. The amount of the inorganic flocculant added is not particularly limited and may be adjusted according to the properties of the wastewater, but is about 100 to 5000 mg / L for ordinary waste products with respect to the wastewater to be treated.

  The order in which the organic coagulant and inorganic flocculant of the present invention are added to the wastewater is not particularly limited, and the organic flocculant of the present invention may be added after the inorganic flocculant is added. An inorganic flocculant may be added after the addition of the coagulant, and further, the organic coagulant and the inorganic flocculant of the present invention may be added simultaneously.

  Next, the pH of the waste water to which the organic coagulant and inorganic flocculant of the present invention are added is adjusted to about 5 to 7 as necessary.

  Next, a polymer flocculant is added to the waste water. There is no particular limitation on the polymer flocculant, and an organic polymer flocculant usually used in wastewater treatment can be used. For example, poly (meth) acrylic acid, copolymers of (meth) acrylic acid and (meth) acrylamide, and anionic organic polymer flocculants such as alkali metal salts thereof, and nonionics such as poly (meth) acrylamide Organic polymer flocculants, homopolymers composed of cationic monomers such as dimethylaminoethyl (meth) acrylate or quaternary ammonium salts thereof, dimethylaminopropyl (meth) acrylamide or quaternary ammonium salts thereof, and those cationic monomers Examples thereof include cationic organic polymer flocculants such as a copolymer with a copolymerizable nonionic monomer. Moreover, there is no limitation in particular also in the addition amount of a polymer flocculant, Although it should just adjust according to the property of waste_water | drain, it is 1-100 mg / L in solid content with respect to the waste_water | drain to process.

  After adding a polymer flocculant and reacting by stirring or the like to agglomerate turbidity in the wastewater, the generated flocs are solidified by agglomeration precipitation treatment, pressurized flotation treatment, filtration, membrane separation treatment, etc. By performing liquid separation treatment, turbidity can be removed from waste water.

  In addition to the organic coagulant, inorganic coagulant, and polymer coagulant of the present invention, a general organic coagulant can be used in combination. Typical organic coagulants include, for example, cationic organic polymers used in normal wastewater treatment such as polyethyleneimine, diallyldimethylammonium chloride, ethylenediamine epichlorohydrin polycondensate, polyalkylene polyamine, and mixtures thereof. It is done. The addition amount is not particularly limited and may be adjusted according to the properties of the waste water. However, it may be generally added in an amount of 1 to 100 mg / L as a solid content to the waste water to be treated.

  Furthermore, if necessary, bactericides, deodorants, antifoaming agents, anticorrosives and the like may be used in combination.

  In such a wastewater treatment method, since the organic coagulant of the present invention containing a cationic polymer having a high cation density and a cross-linked structure and excellent in coagulation performance is used, fine aggregation flocs generated by the inorganic coagulant are more dense. To form a dense floc. Therefore, since the coagulation effect is stabilized and improved, clear treated water can be obtained, and the amount of inorganic coagulant used can be reduced, so that the amount of sludge generated can be suppressed. The aggregation state can be confirmed by evaluating the floc formation time, floc system and sedimentation speed. In addition, the clarity of the treated water can be confirmed by measuring turbidity, chromaticity, and in some cases TOC and COD.

  The sludge dewatering method of the present invention is to dehydrate after adding the organic coagulant and polymer flocculant of the present invention to the sludge. Specifically, first, the organic coagulant of the present invention is added to the wastewater and reacted with the turbidity contained in the wastewater.

  As sludge, organic sludge generated by coagulation sedimentation and pressure flotation treatment of wastewater from general factories such as chemical factories, semiconductor factories, food factories, paper and pulp factories, printing factories and automobile factories, and surplus generated by biological treatment Although organic sludge produced | generated mainly by the coagulation sedimentation in a sludge, a human waste treatment plant, and a sewage treatment plant and biological treatment is mentioned, it is not limited to these. In recent years, diversification of products in factories has led to sludge properties that are more difficult to dehydrate than before, such as a high proportion of organic matter, and fluctuations in sludge properties have increased, making it difficult to perform stable sludge treatment. Yes. Furthermore, due to diversification of eating habits, sludge discharged from human waste treatment plants and sewage treatment plants is difficult to dehydrate and has a large variation in properties, making it difficult to perform stable sludge treatment. Therefore, although it is difficult to obtain a cake having a low water content by the conventional method, the sludge dewatering method of the present invention uses the above-mentioned predetermined organic coagulant, so that it can be treated well. The amount of the organic coagulant of the present invention is not particularly limited and may be adjusted according to the properties of the sludge, but is about 5 to 200 mg / L (evaporation residue conversion) with respect to the sludge slurry.

  Here, when adding the organic coagulant | flocculant of this invention to sludge, you may use together an inorganic flocculant. Examples of the inorganic flocculant include, but are not limited to, a sulfate band, polyaluminum chloride, aluminum chloride, ferric chloride, ferrous sulfate, and a mixture thereof. The amount of the inorganic flocculant added is not particularly limited, and may be adjusted according to the properties of the sludge, but is generally about 100 to 5000 mg / L for a sludge slurry to be treated with a normal commercial product.

  The order of adding the organic coagulant and inorganic flocculant of the present invention to the sludge is not particularly limited, and the organic coagulant of the present invention may be added after the inorganic flocculant is added, and the present invention is applied to sludge. After adding the organic coagulant, an inorganic flocculant may be added, and further, the organic coagulant of the present invention and the inorganic flocculant may be added simultaneously.

  After adding the organic coagulant of this invention and the inorganic flocculant to sludge as needed, pH is adjusted to about 3-7 as needed.

  Next, a polymer flocculant is added to the sludge. The polymer flocculant is not particularly limited, and an organic polymer flocculant usually used in sludge treatment can be used. For example, dimethylaminoethyl (meth) acrylate tertiary salts or quaternary ammonium salts thereof, dimethylaminopropyl (meth) acrylamide tertiary salts or quaternary ammonium salts thereof, homopolymers made of cationic monomers such as diallyldimethylammonium chloride. Examples thereof include cationic polymer flocculants such as polymers or copolymers of nonionic monomers copolymerizable with these cationic monomers. Further, Hoffman degradation products, Mannich modified products, polyamidines, and the like of polyvinylamine and polyacrylamide are also included. Further, a cationic monomer such as a tertiary salt of dimethylaminoethyl (meth) acrylate or a quaternary ammonium salt thereof, a tertiary salt of dimethylaminopropyl (meth) acrylamide or a quaternary ammonium salt thereof or diallyldimethylammonium chloride (meta ) Amphoteric polymer flocculants such as copolymers with anionic monomers such as acrylic acid, acrylamido-2-methylpropane sulfonic acid, vinyl sulfonic acid, maleic acid and itaconic acid. At this time, a copolymerizable nonionic monomer such as (meth) acrylamide may be copolymerized. Furthermore, amphoteric polymers obtained by copolymerizing N-vinylformamide or acetamide with an anionic monomer and hydrolyzing them may also be mentioned. And a homopolymer of (meth) acrylic acid soda, a copolymer of (meth) acrylic acid soda and (meth) acrylamide, and a sulfone monomer such as acrylamide-2-methylpropanesulfonic acid or vinylsulfonic acid An anionic polymer flocculant obtained by copolymerization of In addition, there is no limitation in particular in the addition amount of a polymer flocculant, and what is necessary is just to adjust according to the property of sludge, but it is about 10-2000 mg / L in solid content with respect to the sludge slurry to process.

  After adding a polymer flocculant and reacting by stirring or the like to form a floc floc of sludge, the sludge on which the floc floc has been formed is dewatered by, for example, applying to a sludge dehydrator. There is no restriction | limiting in particular in sludge dehydrator, For example, a belt press, a centrifugal dehydrator, a screw press, a multiple disk type etc. can be selected arbitrarily.

  In addition to the organic coagulant of the present invention and the polymer flocculant, a general organic coagulant can be used in combination. Typical organic coagulants include, for example, cationic organic polymers used in ordinary sludge dewatering treatment, such as polyethyleneimine, diallyldimethylammonium chloride, ethylenediamine epichlorohydrin polycondensate, polyalkylene polyamine, and mixtures thereof. Can be mentioned. The addition amount is not particularly limited and may be adjusted according to the properties of the sludge, but it may be added in an amount of 1 to 100 mg / L as a solid content to the sludge slurry to be treated.

  Furthermore, if necessary, bactericides, deodorants, anticorrosives and the like may be used in combination.

  In such a sludge dewatering method, since the organic coagulant of the present invention containing a polyalkylene polyamine having a high cation density and a crosslinked structure and having excellent coagulation performance is used, a floc having a high density can be formed. Therefore, it becomes difficult for the sludge to be pulverized by mechanical dehydration by the dehydrator, and moisture is easily released from the sludge. Therefore, a cake having a low water content can be obtained. In addition, the aggregation state of sludge can be confirmed by evaluating the floc diameter, gravity filterability, and turbidity of the filtrate. The dehydration effect can be confirmed by measuring the moisture content of the pressed cake.

  In the above, the method of adding the polymer flocculant after adding the organic coagulant to the sludge has been described. However, in the sludge dewatering method of the present invention, the organic coagulant and the polymer flocculant are simultaneously added to the sludge. Also good. In addition, when adding simultaneously, it is set as the sludge dewatering composition which mixed the organic coagulant and the polymer flocculant, the inorganic flocculant added as needed, the said disinfectant, etc. beforehand, and this sludge dewatering composition is added to sludge. You may do it.

  EXAMPLES Hereinafter, although this invention is explained in full detail based on an Example and a comparative example, this invention is not limited at all by this Example.

Example 1
100 g of polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd.) having a solid content concentration of 30% was placed in a three-necked 300 mL separable flask equipped with a stirring blade and a cooling tube. Next, the mixture was ice-cooled to 5 ° C. or lower with stirring, 0.5 mL of a 10 mass% acetone solution of 1,7-octadiene diepoxide, which is a commercially available reagent, was added, and the mixture was stirred for 30 minutes. Next, it was placed in a constant temperature water bath at 60 ° C. and stirring was continued for 2 hours. The obtained solution was used as the organic coagulant of Example 1. The obtained solution was made into a 30 mass% aqueous solution (evaporation residue conversion), and the rotational viscosity measured with a B-type viscometer at 25 ° C. and 30 rpm was 8600 (mPa · s).

(Example 2)
The diepoxide was synthesized with polyethylene glycol diglycidyl ether (manufactured by NOF Corporation, Epiol E-400) under the same conditions and operation as in Example 1 except that 0.7 mL of 10% acetone solution was added. The obtained solution was used as the organic coagulant of Example 2. Moreover, the rotational viscosity which measured the obtained solution by the method similar to Example 1 was 1020 (mPa * s).

(Example 3)
The diepoxide was bisphenol A type liquid epoxy resin (manufactured by Japan Epoxy Resin, JER828) and synthesized under the same conditions and operation as in Example 1 except that 1.3 mL of 10% acetone solution was added. The obtained solution was used as the organic coagulant of Example 3. Moreover, the rotational viscosity which measured the obtained solution by the method similar to Example 1 was 2500 (mPa * s).

Example 4
100 g of polyvinylamine (manufactured by Mitsubishi Chemical Corporation) having a solid content concentration of 10% was placed in a three-necked 300 ml separable flask equipped with a stirring blade and a condenser tube. Next, the mixture was ice-cooled to 5 ° C. or lower with stirring, 0.2 mL of a 10 mass% acetone solution of 1,7-octadiene diepoxide, which is a commercially available reagent, was added, and the mixture was stirred for 30 minutes. Next, it was placed in a constant temperature water bath at 60 ° C. and stirring was continued for 2 hours. The obtained solution was used as the organic coagulant of Example 4. Moreover, the rotational viscosity which measured the obtained solution by the method similar to Example 1 was 1260 (mPa * s).

(Comparative Example 1)
Polyethyleneimine (inherent viscosity (1 N · NaCl, measured at 30 ° C.) = 0.4 dL / g) was used as the organic coagulant of Comparative Example 1.

(Comparative Example 2)
Poly-diallyldimethylammonium chloride (inherent viscosity (1N · NaCl, measured at 30 ° C.) = 0.8 dL / g) was used as the organic coagulant of Comparative Example 2.

(Comparative Example 3)
Polyvinylamine (inherent viscosity (1N · NaCl, measured at 30 ° C.) = 0.6 dL / g) was used as the organic coagulant of Comparative Example 3.

(Comparative Examples 4-6)
Pulp and paper mill general wastewater (SS (turbidity) concentration = 3130 mg / L, raw water turbidity = 860 NTU) 500 mL beakers containing 500 mL were placed in a jar tester, and each beaker was mixed with a sulfuric acid band (18 wt% Al ₂ O ₃ aqueous solution) was added at 200 mg / L (Comparative Example 4), 400 mg / L (Comparative Example 5), and 600 mg / L (Comparative Example 6), and stirred at 150 rpm for 1 minute. Next, after adjusting the pH to 5.5 with 5% NaOH and stirring at 150 rpm for 1 minute, the polymer flocculant P1 (sodium acrylate: acrylamide = 20: 80 (mol%) copolymer, 1N-NaCl). Intrinsic viscosity dL / g = 22) measured at 30 ° C. was added to each beaker in an amount of 1 mg / L and stirred at 150 rpm for 1 minute and then at 50 rpm for 3 minutes to aggregate SS. Table 3 shows the results of measuring the turbidity and floc diameter of each supernatant after 3 minutes of stirring. The floc diameter was measured visually. As a result, the optimum amount of the sulfuric acid band that clarifies the turbidity by an order of magnitude was 600 mg / L.

(Example 5)
500 mL of pulp and paper mill general wastewater used in Comparative Example 4 was placed in a 500 mL beaker and placed in a jar tester. A sulfuric acid band (18 wt% Al ₂ O ₃ aqueous solution) was added to the beaker at 400 mg / L, and 1 at 150 rpm. Stir for minutes. Next, the organic coagulant of Example 1 was added to the waste water so as to be 0.5 mg / L in terms of evaporation residue, and stirred at 150 rpm for 1 minute. The pH was then adjusted to 5.5 with 5% NaOH and stirred for 1 minute at 150 rpm. Thereafter, 1 mg / L of the polymer flocculant P1 was added, and the mixture was first stirred at 150 rpm for 1 minute and then at 50 rpm for 3 minutes to aggregate SS. Table 3 shows the results of measuring the turbidity and floc diameter of the supernatant after 3 minutes from stopping the stirring.

(Examples 6 to 13 and Comparative Examples 7 to 13)
The same operation as in Example 5 was performed except that the type and addition rate of the organic coagulant were as shown in Table 2. The results are shown in Table 2.

  As a result, in Examples 5 to 13 using the organic coagulant of the present invention, clear treated water was obtained as compared with Comparative Examples 7 to 13 using ordinary uncrosslinked organic coagulant, and inorganic agglomeration was performed. As compared with Comparative Example 6 in which the amount of the agent added was large, clear treated water of the same degree was obtained, and it was confirmed that the inorganic coagulant reducing effect and the turbidity removing effect were excellent.

(Comparative Example 14)
The polyamine obtained by the reaction of dimethylamine and epichlorohydrin (1N · NaCl, measured at 30 ° C.) = 0.5 dL / g) was used as the organic coagulant of Comparative Example 14.

(Example 14)
Sludge I Food factory surplus sludge (SS concentration = 1.8% by mass, VSS / SS = 87% by mass, pH 6.5, fiber content / SS = 1.25% by mass) In a 300 mL poly beaker containing inorganic coagulation As an agent, 2000 mg / L of 38 ° Baume ferric chloride was added, and the mixture was stirred for 20 seconds at 250 rpm with a propeller blade stirrer. Next, the organic coagulant of Example 1 was added to the sludge slurry so as to be 20 mg / L in terms of evaporation residue, and stirred for 20 seconds at 250 rpm with a propeller blade stirrer. Next, 150 mg / L of P3 shown in Table 3 below was added as a polymer flocculant, and the mixture was stirred with a spatula at 180 rpm for 30 seconds to coagulate sludge. The floc diameter at that time was measured visually. Next, a vinyl chloride cylinder was placed on a Buchner funnel laid with a 40 mesh nylon filter cloth, and aggregated sludge was poured into it at once, and the amount of filtrate after 10 seconds and the clarity of the separated filtrate were measured. Subsequently, a small amount of sludge remaining on the funnel was taken and pressed at a surface pressure of 1 kg / cm ^{2 for} 60 seconds, and the cake was dried overnight at 105 ° C. to determine the moisture content of the cake. The results are shown in Table 4. In addition, the clarity of the filtrate was observed by visual observation. The case where there was almost no SS (suspended substance) and was transparent was ○, the case where SS was slightly present was △, and the case where SS was cloudy was ×. .

(Examples 15 to 33 and Comparative Examples 15 to 37)
The same operation as in Example 14 was performed except that the types and addition ratios of sludge, inorganic flocculant, organic flocculant and polymer flocculant were shown in Tables 4 and 5. In the table, the examples are indicated as “actual” and the comparative examples as “ratio”. Sludge II is a pulp and paper factory pressurized floating sludge (SS concentration = 2.6 mass%, VSS / SS = 73 mass%, pH 5.5, fiber content / SS = 36 mass%), and sulfuric acid band is 18 wt%. An Al ₂ O ₃ aqueous solution was used. The results are shown in Tables 4 and 5.

  As a result, in Examples 14 to 33 using the organic coagulant of the present invention, the floc strength is higher than that of Comparative Examples 15 to 37 using an ordinary organic coagulant, and a cake having a low water content is obtained. I was able to confirm.

Claims (2)

At least one of a cationic polymer flocculant and an amphoteric polymer flocculant, an organic coagulant containing a cationic polymer obtained by reacting a polymer having a primary amino group or a secondary amino group with a diepoxide compound, and inorganic flocculence A sludge dewatering method in which a sludge is added to sludge and then dehydrated.
The polymer having the primary amino group or the secondary amino group is polyethyleneimine or polyvinylamine,
The diepoxide compound is at least one selected from the group consisting of 1,7-octadiene diepoxide, polyethylene glycol diglycidyl ether and bisphenol A type liquid epoxy resin;
The rotational viscosity of a 30% by weight aqueous solution of the cationic polymer measured with a B-type viscometer at 25 ° C. and 30 rpm is 600 to 10,000 mPa · s,
A homopolymer comprising the cationic polymer flocculant comprising a quaternary ammonium salt of dimethylaminoethyl (meth) acrylate, a quaternary ammonium salt of dimethylaminopropyl (meth) acrylamide, or a cationic monomer of diallyldimethylammonium chloride, Or a copolymer of nonionic monomers copolymerizable with these cationic monomers,
The amphoteric polymer flocculant is I copolymer der the anionic monomer is a cationic monomer and (meth) acrylic acid, a quaternary ammonium salt of dimethylaminoethyl (meth) acrylate, and the anionic sludge dewatering methods towards the monomer is characterized der Rukoto having a large mole% than the cationic monomer.   The sludge dewatering method according to claim 1, wherein a ratio of the diepoxide compound is 0.001 to 0.1 mol% with respect to an amino group of the polymer having the primary amino group or the secondary amino group. .