JP2011167651A - Treatment method of sewage sludge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment method for treating sludge using a dissolving facility providing a dissolving performance equal to that of the dissolving method using the conventional dissolving facility, and usable even in a narrow space, when efficiently dewatering a large amount of sludge from a sewage treatment facility. <P>SOLUTION: A dispersion type polymer coagulant and dilution water are fed into a pipe to be brought into contact with each other. The mixed diluted liquid is fed to a sludge coagulation/mixing tank or a mechanical condensing facility in the sludge treatment facility, to coagulate or condense the sludge produced from sewage biological treatment. That is, the coagulated sludge is transferred to a belt type condenser from the sludge coagulation/mixing tank for condensing, or the diluted liquid is directly fed to a centrifugal condenser for condensing operation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a method for treating sewage sludge, and more specifically, a dispersion polymer flocculant and dilution water are supplied into a pipe, brought into contact with each other in the pipe, and mixed and prepared as a sludge treatment facility. It is related with the processing method of the sewage sludge characterized by supplying to the concentrator in and performing a coagulation operation and concentration operation.

Since the polymer flocculant is usually used after being diluted 200 times or more by using a dissolution facility, the dissolution facility has become relatively large and has been difficult to install. Dispersion type organic polymer flocculant dissolution equipment suitable for a processing facility having a small installation area and no place for newly installing a dissolution tank is desired.

Sludge generated from sewage, human waste, or various industrial effluents is hardly dehydrated due to various causes. Further, since it is important to minimize the energy required for drying and incineration for final disposal of the dehydrated cake, it is an important issue to reduce the water content of the dehydrated cake as much as possible. An effective flocculation method for solving this problem has been demanded, and many proposals have been made to use a combination of a plurality of organic polymer flocculants. For example, instead of using a conventional cationic organic polymer flocculant alone, a combination of a cationic organic polymer flocculant and an anionic organic polymer flocculant (Patent Document 1 or Patent Document 2) is used. The optimum method is selected according to the type and dehydrator, and is now widely used. However, since these methods use a plurality of organic polymer flocculants, it is necessary to add a new dissolution facility to a processing facility that has only one dissolution facility so far. This method could not be adopted. As a method for solving this problem, equipment that efficiently supplies a liquid organic polymer flocculant with a line mixer is equivalent to this (Patent Document 3). As a result of reproducing and verifying this equipment, the equipment is discharged from the line mixer. The viscosity of the dissolved liquid organic polymer flocculent solution was 70% or less when completely dissolved, and an undissolved one was confirmed visually. In this state, it is presumed that not only is the amount of addition more than a predetermined amount not economical, but also undissolved material adheres to piping facilities, dehydrators and the like.
Japanese Patent Laid-Open No. 10-249399 JP 2001-286898 A JP 7-328319 A

The problem to be solved by the present invention is that the dispersion performance of the dispersion type polymer flocculant adjusted by the dissolution equipment that can be used even in a narrow place is obtained, which is equivalent to the dissolution method using the conventional dissolution equipment. An object of the present invention is to provide a sludge treatment method that is more efficient than conventional methods, in which a sludge is dehydrated after a liquid is provided, subjected to a concentration operation by a mechanical concentration facility using the diluted liquid.

As a result of repeated studies to solve the above problems, the present inventors have reached the invention described below. That is, the invention of claim 1 is that the dispersion type polymer flocculant and the dilution water are supplied into the pipe, brought into contact with the pipe, mixed and prepared, and the diluted liquid is supplied to the concentrator in the sludge treatment facility to perform the flocculation operation. And a sewage sludge treatment method characterized by performing a concentration operation.

The invention of claim 2 is the sewage sludge treatment method according to claim 1, wherein the concentrator is a centrifugal concentrator.

According to a third aspect of the present invention, the dilution liquid is supplied to a sludge coagulation mixing tank, and after the coagulation operation is performed, the dilution liquid is transferred to a belt concentrator and the concentration operation is performed. It is a processing method.

The invention of claim 4 uses a T-shaped joint as means for bringing the dispersed polymer flocculant and the dilution water into contact with each other in a pipe, and the dispersion polymer flocculant and the The sewage sludge of the sewage sludge according to claim 1 or 3, wherein a nozzle having a function of increasing a flow rate of the dilution water and generating a turbulent flow is installed at a position of 10 mm or more and 100 mm or less in front of the portion in contact with the dilution water. It is a processing method.

The invention of claim 5 is the sewage sludge treatment method according to claim 4, wherein the nozzle is a wing nozzle.

The invention of claim 6 is characterized in that a check valve is installed in a pipe of the dispersed polymer flocculant within 200 mm from the point where the dispersed polymer flocculant and the dilution water come into contact. 4. A method for treating sewage sludge as described in 4.

The invention according to claim 7 is the sewage sludge treatment method according to claim 1 or 3, wherein the dispersion-type polymer flocculant is a water-in-oil polymer emulsion.

The invention of claim 8 is characterized in that the water-in-oil emulsion is one or two selected from a hydrophobic monomer, a cationic monomer, an anionic monomer, and a monomer having a polyoxyethylene chain. The sewage sludge treatment method according to claim 7, wherein an oil-soluble polymer comprising a copolymer with a seed is blended.

The method of treating sewage sludge according to the present invention is to supply a dispersion polymer flocculant and dilution water into a pipe, contact the pipe in the pipe, and mix and prepare the diluted solution to a concentration facility in the sludge treatment facility. It is characterized by carrying out an agglomeration operation and a concentration operation. When the concentrator coagulation mixing tank is a centrifugal concentrator, the diluting solution can be injected into the line, and aggregation and centrifugal concentration can be performed continuously. In the case of a belt concentrator, the diluting solution is supplied to a sludge flocculation mixing tank, and after the flocculation operation is performed, the concentration operation is performed. By concentrating the sludge before the dehydration operation, the dehydration effect can be improved and the moisture content of the cake can be reduced. The treatment method of the present invention is expected to be an effective method in a facility that must treat a large amount of sludge, such as a sewage treatment plant. For example, in facilities such as sludge treatment centers in large cities, it is effective for equipment that concentrates excess sludge sent from each sewage treatment plant and sludge generated from the first sedimentation basin, that is, mixed raw sludge, and then dewaters. It is thought that it is a method.

In the present invention, a water-in-oil emulsion is used as a dispersion type polymer flocculant, and a hydrophobic monomer, a cationic monomer, an anionic monomer, and a polyoxygen are added to the water-in-oil emulsion. It is preferable to blend an oil-soluble polymer composed of a copolymer with one selected from monomers having an ethylene chain. That is, by adding the oil-soluble polymer, the solubility is improved and the generation of undissolved dispersed particles can be suppressed, for example, in the case of mixing with dilution water in a line to prepare a diluted solution.

As an effect of the present invention, a dilute solution of a dispersed polymer flocculant can be easily prepared even in a small installation area. In sewage treatment plants, treated water is often used for dissolved water, such as polymer flocculants. In general, treated water has poor water quality compared to tap water, such as a high salt concentration, and the flocculant deteriorates quickly. However, tap water is expensive and may not be used. In the case of the line dissolution according to the present invention, it is considered that there is almost no deterioration because it takes a short time until it is dissolved and used. Therefore, performance different from the case where it is dissolved and used in a batch type can be expected.

In the sludge treatment method of the present invention, the dilute solution is supplied to the coagulation mixing tank to coagulate the sludge, and then transferred to a mechanical sludge concentrating facility for concentration operation and temporarily stored in a tank or the like. Thereafter, it can be mixed with other sludge to dehydrate the sludge. That is, when a large amount of sludge is efficiently treated as in a sewage treatment plant, there is an advantage that sludge can be treated efficiently. In the case of surplus sludge from a sewage treatment plant, there is usually no chemical injection, but when the coagulation state deteriorates due to seasonal fluctuations in the sludge, etc., a polymer flocculant is added, concentrated by a concentration facility, and then concentrated to the sludge. If a polymer flocculant is added, supplied to a dehydrator and dehydrated, the recovery rate can be improved by about 10 percentage points, and as a result, it can be expected to save electricity costs. Furthermore, by reducing the load of the return water by improving the recovery rate, it can be expected to reduce the electricity bill of the biological treatment blower.

In the present invention, since a dispersion type polymer flocculant is used, it is easy to prepare a diluted solution. The dispersed particles are dissolved to some extent by simply contacting and mixing the dispersion type polymer flocculant and the dilution water in the pipe, and the remaining dispersed particles are supplied to the sludge dehydrator as they are. In the sludge dewatering machine, a mixture of diluted solution and undissolved dispersed particles is added, and sludge and undissolved dispersed particles are mixed. At this time, the undissolved dispersed particles are dissolved, and as a result, new agglomerated flocs are dissolved. It also produces a positive effect on the sludge aggregation process. That is, it can be expected that the agglomeration flocs that have been dissolved by agitation will also agglomerate.

In order to further secure the basic form, the following means can be additionally installed in the present invention. That is, the dispersion of the dispersion type polymer flocculant used in the present invention has a T-shaped joint connected to the dilution water pipe, and the dilution water pipe and the dispersion type polymer flocculant pipe are connected by the T-shaped joint. A nozzle having a function of increasing the flow rate of water and generating turbulence at a position 10 mm or more and 100 mm or less in front of the T-shaped joint with respect to the flow direction of the dilution water is installed in the dilution water pipe, and the dispersion It can be prepared by bringing the type polymer flocculant and the dilution water into contact with each other in a pipe, mixing them, and then diluting with a line mixer.

Conventionally, in order to prepare a dilute solution of a polymer flocculant not only in a dispersion type but also in a powder type, a dissolving water is put into a dissolution tank equipped with a stirrer, and a polymer is prevented from generating coarse particles while rotating the stirrer. Add a flocculant little by little, disperse and stir for a certain time to prepare a diluted solution. This equipment requires a large tank and a powerful motor in order to prepare a diluting solution of several t to several tens of t at a time, and it is necessary to secure a certain area for the installation area. If it adjusts like this invention compared with the said installation, an installation area and installation expense can be reduced significantly. For example, when dewatering by supplying 10 tons of sludge per hour, the sludge solid content concentration is 4% by mass, and the polymer flocculant is supplied at an addition amount of 0.2% by mass with respect to 1% by mass of sludge solid content. Then, it is necessary to prepare a 24 t solution in 12 hours. Even a 0.3% by mass solution requires 16 t.

However, on the other hand, when supplying the polymer flocculant with the same sludge, addition amount and dissolution concentration as above, the supply amount per minute is 33.3 kg / min at 0.2% by mass. In the method of the present invention in which the flocculant and the dilution water are mixed to prepare a dilute solution, the flow rate is 167 mL / min when the concentration of the stock solution of the dispersive polymer flocculant is 40% by mass and the specific gravity is 1. A pump is sufficient. If dilution water is supplied at 33.3 L / min, the flow rate is 18.5 m / min when the inner diameter of the dilution water pipe is 1.5 cm, and the stock solution of the dispersed polymer flocculant is 1/10 of this speed. At a flow rate of 167 mL / min. In this case, when the dilution water pipe and the dispersion type polymer flocculant pipe are connected by a T-shaped joint, the inner diameter of the dispersion type polymer flocculant pipe is 3.4 mm. Therefore, if a check valve is installed within 200 mm from the point where the T-shaped joint and the dispersive polymer flocculant pipe are in contact, the amount of undiluted solution remaining in the pipe is only about 1.8 cc.

In the present invention, a nozzle having a function of increasing the flow rate of water and generating a turbulent flow at a position 10 mm or more and 100 mm or less in front of the T-shaped joint with respect to the flow direction of the dilution water is installed in the dilution water pipe. When contacted with dilution water in the tube, a mechanism for suppressing the generation of insoluble particles of dispersible polymer flocculant (particles dissolved only on the surface but not dissolved on the inside, so-called lumps or fish eyes) can be installed. This mechanism disperses dispersed polymer flocculant particles in the pipe at a high flow rate and disperses them in a turbulent water stream, minimizing the generation of insoluble particles, and making mixing and dilution in a line mixer more efficient. Can be done automatically. Specific members having such a function include those manufactured by Noritake Company Limited.

Thereafter, the suspension in which the dispersed polymer flocculant particles and the dilution water are mixed is passed through a line mixer to dissolve the particles to prepare a diluted solution. This line mixer is relatively inexpensive compared to a pump, has a simple structure, is light in weight, is easy to handle, and is very convenient to use. Specific examples include Kalman Mixer Series-F1, F2, F3, KS2, and KT2 manufactured by Chilling Industries Co., Ltd. When dissolution is insufficient with one unit, two units can be connected in series.

The dispersion type polymer flocculant used in the present invention includes a water-in-oil polymer emulsion and a salt water polymer dispersion. Among these, a polymer dispersion of salt water is prepared by preparing an aqueous solution of a polyvalent anion salt such as ammonium sulfate, charged with a mixture of a cationic monomer or a nonionic monomer, and having amphoteric water solubility. In the case of a polymer, an anionic monomer can be squeezed, and a polymer dispersant soluble in the aqueous salt solution can be used as a dispersant in the presence of stirring to carry out dispersion polymerization and synthesis.

Next, the dispersant will be described. As the polymer dispersant, either a nonionic or cationic polymer can be used, but a cationic polymer is more preferable. Cationic polymers include acrylic cationic monomers such as inorganic acid and organic acid salts such as dimethylaminoethyl (meth) acrylate and dimethylaminopropyl (meth) acrylamide, or methyl chloride and benzyl chloride. It is a copolymer of quaternary ammonium salt and acrylamide. For example, (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxy 2-hydroxypropyltrimethylammonium chloride, (meth) acryloylaminopropyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, ( Examples thereof include (meth) acryloyloxy 2-hydroxypropyldimethylbenzylammonium chloride, (meth) acryloylaminopropyldimethylbenzylammonium chloride, and a copolymer of these monomers and nonionic monomers may be used. Also, diallylamine polymers such as dimethyldiallylammonium chloride polymer can be used.

Examples of nonionic polymers include (co) polymers of the above nonionic monomers, polyvinyl alcohol, styrene / maleic anhydride copolymers or fully amidated products of butene / maleic anhydride copolymers. Etc.

The molecular weight of the ionic polymer is 5,000 to 3 million, preferably 50,000 to 1.5 million. The molecular weight of the nonionic polymer is 1,000 to 1,000,000, preferably 1,000 to 500,000. The amount of these polymer dispersants added to the monomer is 1/100 to 1/10, preferably 2/100 to 5/100.

  The temperature at the time of superposition | polymerization is 5-50 degreeC, Preferably it is 15-40 degreeC. When the temperature is higher than 50 ° C., it is difficult to control the polymerization, and a rapid temperature rise or agglomeration of the polymerization solution occurs, so that a stable dispersion with a high degree of polymerization is not generated.

On the other hand, a water-in-oil polymer emulsion is an ionic monomer, or an ionic monomer, a monomer that can be copolymerized, and a molar ratio that maintains a water-soluble polymer formed with these monomers. The monomer mixture containing the added crosslinkable monomer is water, at least one oily substance consisting of at least water and an immiscible hydrocarbon, and an amount effective to form a water-in-oil emulsion and HLB. These surfactants are mixed and vigorously stirred to form a water-in-oil emulsion and polymerize.

Examples of oily substances composed of hydrocarbons used as dispersion media include paraffins, mineral oils such as kerosene, light oil, and middle oil, or hydrocarbon-based synthetics having characteristics such as boiling point and viscosity substantially in the same range as these. An oil or a mixture thereof may be mentioned. As content, it is the range of 20 mass%-50 mass% with respect to the water-in-oil type emulsion whole quantity, Preferably it is the range of 20 mass%-35 mass%.

Examples of at least one surfactant having an amount effective to form a water-in-oil emulsion and HLB are HLB 1-8 nonionic surfactants, specific examples of which include sorbitan monooleate Sorbitan monostearate, sorbitan monopalmitate and the like. The addition amount of these surfactants is 0.5 to 10% by mass, preferably 1 to 5% by mass, based on the total amount of the water-in-oil emulsion.

In this case, the emulsion emulsified with a high HLB surfactant to form a water-in-oil emulsion and polymerized is compatible with water as it is, so there is no need to add a phase inversion agent. The HLB of these surfactants is 9-20, preferably 11-20. Examples of such surfactants are cationic surfactants and HLB 9-15 nonionic surfactants, such as polyoxyethylene polyoxypropylene alkyl ether systems, polyoxyethylene alcohol ether systems, and the like It is.

When emulsified and polymerized with a low-HLB surfactant, a hydrophilic interfacial modifier called a phase inversion agent is added after the polymerization to make the emulsion particles covered with the oil film easy to adapt to water, The molecule is treated so that it is easily dissolved, diluted with water and used for each application. Examples of hydrophilic surfactants are cationic surfactants and nonionic surfactants of HLB 9-15, such as polyoxyethylene polyoxypropylene alkyl ether systems and polyoxyethylene alcohol ether systems. is there.

The polymerization is carried out under a nitrogen atmosphere under a polymerization initiator such as 2,2′-azobis (amidinopropane) dichloride or 2,2′-azobis [2-
(5-Methyl-2-imidazolin-2-yl) propane] Adds a water-soluble azo polymerization initiator such as dihydrochloride or a water-soluble redox polymerization initiator such as ammonium persulfate and sodium bisulfite in combination. Then, radical polymerization is performed with stirring.

In the case of producing a dispersion type polymer flocculant, as a raw material monomer, (meth) acryloyloxyethyltrimethylammonium chloride which is a quaternized product of a tertiary amino-containing monomer with methyl chloride or benzyl chloride, (Meth) acryloyloxy 2-hydroxypropyltrimethylammonium chloride, (meth) acryloylaminopropyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloyloxy 2-hydroxypropyldimethylbenzylammonium chloride And (meth) acryloylaminopropyldimethylbenzylammonium chloride. A dimethyldiallylammonium monomer represented by the general formula (2) can also be used, and examples thereof include dimethyldiallylammonium chloride and diallylmethylbenzylammonium chloride.

When producing an amphoteric water-soluble polymer, in addition to the cationic and nonionic monomers, an anionic monomer represented by the general formula (3) is further copolymerized. For example, either a sulfone group or a carboxyl group may be used, and both may be used in combination. Examples of the sulfone group-containing monomer are vinyl sulfonic acid, vinyl benzene sulfonic acid, 2-acrylamido 2-methylpropane sulfonic acid, and the like. Examples of the carboxyl group-containing monomer include methacrylic acid, acrylic acid, itaconic acid, maleic acid, and p-carboxystyrene.

Examples of nonionic monomers include (meth) acrylamide, N, N-dimethylacrylamide, vinyl acetate, acrylonitrile, methyl acrylate, 2-hydroxyethyl (meth) acrylate, diacetone acrylamide, and N-vinyl pyrrolidone. N-vinylformamide, N-vinylacetamide, acryloylmorpholine, acryloylpiperazine and the like.

The water-in-oil polymer emulsion used in the present invention can be made into a crosslinkable water-soluble polymer in the presence of a crosslinkable monomer or a heat crosslinkable monomer. Examples of such crosslinkable monomers include monomers having a plurality of polymerizable double bonds such as methylene bisacrylamide and ethylene glycol di (meth) acrylate, or N, N-dimethylacrylamide monomers. And a heat-crosslinkable monomer. The addition amount is 0.0005 to 0.1 mol%, preferably 0.0010 to 0.05%, more preferably 0.0015 to 0.03%, based on the total number of moles of the monomer mixture. is there. In order to adjust the degree of polymerization, it is effective to use isopropyl alcohol together with 0.1 to 5% by mass of the monomer.

If the water-in-oil type polymer emulsion used in the present invention has a very high liquid viscosity, it is difficult to disperse in the sludge. Therefore, the water-in-oil polymer emulsion is preferably several tens to 10,000 mPa · s, more preferably 50 to 5,000 mPa · s. The molecular weight of the cationic and / or amphoteric water-soluble polymer constituting the water-in-oil polymer emulsion is preferably 3 million to 20 million, and more preferably 5 million to 10 million.

However, sludge is generally high in concentration, so it is an important factor to efficiently mix the dispersion into the sludge. Therefore, when the water-in-oil polymer emulsion is added, if it is vigorously stirred, a good agglomerated state can be obtained, but this condition cannot always be obtained at the dehydration site. In the present invention, in order to improve this point, the water-in-oil emulsion is examined from a hydrophobic monomer, a cationic monomer, an anionic monomer, and a monomer having a polyoxyethylene chain. It has been found that if an oil-soluble polymer composed of a copolymer of one or two types selected is added to a water-in-oil polymer emulsion, the dispersibility in sludge and the solubility of the emulsion can be improved.

The oil-soluble polymer will be described below. The oil-soluble polymer used in the present invention is selected from a hydrophobic monomer and a monomer having a cationic group, a monomer having an anionic group, or a monomer having a polyoxyethylene chain in the molecule It can be produced by copolymerization with one or two of the above. The hydrophobic monomer is a monomer having an aromatic ring such as styrene or α-methylstyrene or an aromatic ring to which an alkyl group is added, an aromatic ring having 6 to 20 carbon atoms such as an α-olefin, or an aliphatic vinyl compound. Moreover, the alkyl (meth) acrylate which has a C4-C18 alkyl group can also be used.

Specific examples of the alkyl (meth) acrylate include the following. That is, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, and the like.

The monomer having a cationic group is dialkylaminoalkylacrylamide or dialkylaminoalkyl (meth) acrylate. Specific examples of the dialkylaminoalkylacrylamide include dimethylaminopropylacrylamide and diethylaminopropylacrylamide. Specific examples of the dialkylaminoalkyl (meth) acrylate include dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate and the like.

Examples of the monomer having an anionic group are methacrylic acid or acrylic acid. Moreover, as an example of the monomer which has a polyoxyethylene chain in a molecule | numerator, it is a polyoxyethylene (meth) acrylate, and is 3-20 as a polymerization degree of a polyoxyethylene.

Of these hydrophobic monomers, a monomer having a cationic group, a monomer having an anionic group, or a combination of copolymerization with a monomer having a polyoxyethylene chain in the molecule is most preferable. Is a hydrophobic monomer such as 2-ethylhexyl acrylate or lauryl acrylate, dimethylaminoethyl methacrylate as a cationic monomer, methacrylic acid or acrylic acid as a monomer having an anionic group, and a single unit having a polyoxyethylene chain. It is polyoxyethylene (meth) acrylate as a monomer, and the polymerization degree of polyoxyethylene is most preferably 4 to 10.

The molar ratio of the hydrophobic monomer in the oil-soluble polymer is preferably 60 to 95 mol%, more preferably 80 to 95 mol%. On the other hand, the molar ratio of the monomer having a cationic group, the monomer having an anionic group, and the monomer having a polyoxyethylene chain is preferably 5 to 40 mol%, more preferably 5 to 20 mol. %.

The oil-soluble polymer can be prepared by a conventional polymerization method after preparing the monomer mixture. Examples of the polymerization method include solution polymerization, bulk polymerization, and suspension polymerization. A preferred method is solution polymerization which is easy to handle and handle the polymerization. In the case of solution polymerization, polymerization is carried out at a monomer concentration of 20 to 80% by mass%, preferably 40 to 60%. In this case, the polymerization solvent is preferably a nonpolar organic solvent. That is, aromatic and aliphatic hydrocarbons are particularly preferred, and it is convenient to use the same organic solvent as the organic solvent used as a dispersion medium for water-in-oil emulsion polymerization, and paraffin having a boiling point of 190 ° C to 230 ° C. Or isoparaffin is preferable.

The method for adding the oil-soluble polymer of the present invention can be arbitrarily used. That is, after polymerizing the oil-soluble polymer, an appropriate amount is added and dispersed in the water-in-oil polymer emulsion. Alternatively, in particular, when adding a cationic oil-soluble polymer, an acid in an amount proportional to the amino group in the cationic oil-soluble polymer is added to the water-in-oil dispersion in advance, and the cation after polymerization is added. An oil-soluble polymer can also be added. Preferably, an acid is added in advance, and a cationic oil-soluble polymer is added after polymerization. When other oil-soluble polymers are used, there is no particular limitation.

The acid added as described above is to neutralize and dissociate the amino group of the cationic oil-soluble polymer to enhance the dispersibility of the cationic oil-soluble polymer and improve the function as a dispersion stabilizer. Another object is to prevent degradation of the water-soluble polymer by adjusting the pH of the water-in-oil dispersion after polymerization. As the acid used for such a purpose, any acid may be used as long as it does not adversely affect the water-soluble polymer in the aqueous phase and the dispersion form retention. Specific examples include succinic acid, acetic acid, citric acid, adipic acid and the like.

The amount of acid to be added is 30 mol% or more based on the amino group in the molecule of the cationic oil-soluble polymer in the water-in-oil monomer dispersion before polymerization or the water-in-oil polymer dispersion after polymerization. Added. Further, it is preferably 30 mol% or more and 1000 mol% or less, more preferably 50 mol% or more and 500 mol% or less.

When the water-in-oil polymer emulsion is diluted with water, the oil-soluble polymer used in the present invention is improved in compatibility with water and can be prepared earlier than when no oil-soluble polymer is added. An oil film is present on the surface of the emulsion particles, and it is difficult to mix with water, so water-soluble polymers cannot be easily dissolved. The so-called phase inversion agents help this, but these phase inversion agents are generally high HLB, ie, hydrophilic surfactants, and low molecular weight compounds. The hydrophilic surfactant does not mix with the oil and helps to disperse the oil film that separates from the emulsion particle surface in water. Since the oil-soluble polymer used in the present invention is also dissolved in oil, it is presumed that it is also present in the oil film on the surface of the emulsion particles. Therefore, when diluting with water, the diluting solution can be prepared quickly, and when it is not diluted and added to sludge etc. in the state of dispersion, it is quickly diluted and dissolved with moisture in the sludge, resulting in excellent agglomeration. It seems to be effective.

Here, the sludge concentrator will be described. At present, two types of belt concentrators and centrifugal concentrators are the mainstream. As with dehydrators, in the case of belt concentrators, sludge and coagulant are coagulated and mixed in a coagulation mixing tank and then supplied to the belt concentrator and concentrated. Mix with other sludge and perform dehydration operation. In the case of a centrifugal concentrator, it is directly supplied to the concentrator and mixed in the concentrator. Such mechanical concentration equipment has an advantage of efficiently treating the next sludge dewatering when efficiently treating a large amount of sludge as in a sewage treatment plant, and is not common in treatment facilities of other industries. In the case of a belt concentrator, regardless of the type of sludge such as mixed raw sludge and surplus sludge, sludge and flocculant are mixed in a sludge agglomeration mixing tank and then supplied to the concentrator. The amount of the flocculant added is about 0.2 to 0.4% of the solid content with respect to sludge. In the case of a centrifugal concentrator, when a flocculant is added, the solid content with respect to sludge is about 0.03 to 0.2% and is directly supplied to the centrifugal concentrator.

In the case of a centrifugal concentrator, a flocculant is usually added to the mixed raw sludge in an amount of about 0.1%, but the excess sludge can usually be added without a flocculant. If the excess sludge from the sewage treatment plant is concentrated by a concentration facility under non-chemical injection conditions, then a polymer flocculant is added to the concentrated sludge, and then supplied to a dehydrator and dehydrated to improve the recovery rate by about 10 percentage points. As a result, it can be expected to save electricity costs. Furthermore, by reducing the load of the return water by improving the recovery rate, it can be expected to reduce the electricity bill of the biological treatment blower. Usually, there is no chemical injection equipment in the centrifugal concentration equipment for excess sludge, but if you use the diluted polymer flocculant prepared by the line dissolution of the present invention, it will not take place, so it can be installed easily. Is also possible.

(Examples) Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

(Synthesis Example 1) In a reaction vessel equipped with a stirrer and a temperature control device, 24.75 g of isoparaffin having a boiling point of 190 ° C. to 230 ° C., 5.48 g (30 mol%) of dimethylaminoethyl methacrylate (hereinafter abbreviated as DMM), lauryl Acrylate (12 carbon atoms, hereinafter abbreviated as LA) 19.52 g (70 mol%), 3-mercapto 1,2-propanediol 0.25 g, dimethyl-2,2-azobisisobutyrate (V made by Wako Pure Chemical Industries, Ltd.) -601) 0.5 g (2% by mass of monomer) was charged and dissolved. The temperature of the monomer solution was kept at 70 to 73 ° C., nitrogen substitution was performed for 30 minutes, and the polymerization reaction was started. The reaction was completed at a reaction temperature of 71 ± 2 ° C. for 5 hours to complete the reaction. The weight average molecular weight determined by gel permeation chromatography was 8100. This is referred to as prototype-1.

(Synthesis Example 2) In a reaction vessel equipped with a stirrer and a temperature control device, 24.75 g of isoparaffin having a boiling point of 190 ° C to 230 ° C was added to 13.6 g (35 mol%) of polyoxyethylene methacrylate (polyoxyethylene polymerization degree 6). ), 2-ethylhexyl acrylate 18.60 g (65 mol%), 3-mercapto 1,2-propanediol 0.16 g, dimethyl-2,2-azobisisobutyrate (V-601, manufactured by Wako Pure Chemical Industries, Ltd.) 0 0.5 g (2% by mass of monomer) was charged and dissolved. The temperature of the monomer solution was kept at 70 to 73 ° C., nitrogen substitution was performed for 30 minutes, and the polymerization reaction was started. The reaction was completed at a reaction temperature of 71 ± 2 ° C. for 5 hours to complete the reaction. The weight average molecular weight determined by gel permeation chromatography was 7500. This is designated as prototype-2.

(Synthesis Example 3) In a reaction vessel equipped with a stirrer and a temperature controller, 24.75 g of isoparaffin having a boiling point of 190 ° C to 230 ° C was added to 11.3 g (35 mol%) of methacrylic acid, and 44.8 g of 2-ethylhexyl acrylate ( 65 mol%), 0.28 g of 3-mercapto 1,2-propanediol, 0.5 g of dimethyl-2,2-azobisisobutyrate (V-601, manufactured by Wako Pure Chemical Industries) (2% by mass of monomer) Was charged and dissolved. The temperature of the monomer solution was kept at 70 to 73 ° C., nitrogen substitution was performed for 30 minutes, and the polymerization reaction was started. The reaction was completed at a reaction temperature of 71 ± 2 ° C. for 5 hours to complete the reaction. The weight average molecular weight determined by gel permeation chromatography was 6200. This is Prototype-3.

(Synthesis Example 4) In a reaction vessel equipped with a stirrer and a temperature controller, 24.75 g of isoparaffin having a boiling point of 190 ° C to 230 ° C was added to 6.3 g of polyoxyethylene methacrylate (polyoxyethylene polymerization degree 6) (20 mol%). ), 2-ethylhexyl acrylate 24.4 g (75 mol%), dimethylaminoethyl methacrylate 1.4 g (5 mol%), 3-mercapto 1,2-propanediol 0.16 g, dimethyl-2,2-azobis 0.5 g of isobutyrate (V-601, manufactured by Wako Pure Chemical Industries, Ltd.) (2% by mass of monomer) was charged and dissolved. The temperature of the monomer solution was kept at 70 to 73 ° C., nitrogen substitution was performed for 30 minutes, and the polymerization reaction was started. The reaction was completed at a reaction temperature of 71 ± 2 ° C. for 5 hours to complete the reaction. The weight average molecular weight determined by gel permeation chromatography was 8500. This is Prototype-4.

1% by mass of each of each of oil-soluble polymer prototype-1 to oil-soluble polymer prototype-4 prepared in Synthesis Examples 1 to 4 was added to the water-in-oil polymer emulsion described in Table 1 with respect to the total amount of the liquid, Test emulsion aggregating agents EM-1 to EM-3 having a water-soluble polymer concentration of 40% by mass were prepared. In addition, water-in-oil polymer emulsion EM-5 to which oil-soluble polymer prototype-1 to oil-soluble polymer prototype-4 were not added was also prepared. Further, a salt water dispersion type DI-1 to which no oil-soluble polymer was added was also prepared. The results are shown in Table 1.

(Table 1)
DMQ: acryloyloxyethyltrimethylammonium chloride DMC: methacryloyloxyethyltrimethylammonium chloride AAM: acrylamide, AAC: acrylic acid,
MBA: Methylenebisacrylamide (mass% with respect to the total amount of monomers)
EM: water-in-oil emulsion, DI: salt water dispersion emulsion coagulant viscosity: mPa · s,

FIG. 1 shows a dilution / concentration / dehydration system of the present invention. The dilution water supply pump 2 is operated, dilution water is supplied at a rate of 20 L / min from a water tank (not shown) through the dilution water pipe 1, and from the dispersion type polymer flocculant stock solution tank (not shown) through the pipe 8. The dispersion type polymer flocculant stock solution supply pump 9 was operated, and the water-in-oil emulsion EM-1 was supplied at a rate of 100 mL / min. The diluting water passes through the diluting water flow rate adjusting valve 4 and the nozzle 5 having a function of generating turbulent flow, and at the T-shaped joint 6, the diluting water is combined with the dispersed polymer flocculant stock solution that has passed through the check valve 10 and mixed. -Dilution is performed, almost dilution is performed in the line mixer 7, and it is supplied to the sludge coagulation mixing tank 12. The sludge is supplied from a sludge storage tank (not shown) to the sludge agglomeration mixing tank 12 through the pipe 11, stirred and mixed, transferred to the sludge dehydrator (not shown) through the pipe 14, and dewatering is performed. When dilution water and a dispersion type polymer flocculant stock solution are supplied under the above conditions, the dilution ratio is 200 times. The batch type polymer flocculant dilution tank 13 is used for comparison, and can be stirred for 1 hour by the batch type polymer flocculant dilution tank 13 by propeller rotation shown in the dilution system flow of FIG. .

Next, the diluted solution prepared by the dilution system was directly supplied to the sludge treatment apparatus, and a sludge dewatering test was performed. Using the sewage mixed raw sludge (mixture of surplus sludge and first precipitated sludge, pH 7.54, ss 11,000 mg / L), the sludge is supplied to a sludge coagulation mixing tank equipped with a stirrer at 11 m ³ / hr. Moreover, dilution water is supplied at a rate of 40 L / min with tap water, and the water-in-oil emulsion EM-1 is supplied from the stock solution tank at a rate of 200 mL / min, so that 40% by mass of the stock solution is reduced to 0.2% by mass. Each pump was set to dilute. Thereafter, the dilute water-in-oil emulsion EM-1 discharged from the line mixer was supplied to the sludge aggregation / mixing tank at 183 L / hr (corresponding to an addition amount of 0.3 mass% with respect to ss). This agglomerated sludge was concentrated using a belt concentrator (not shown) and transferred to a concentrated sludge storage tank. The sludge after concentration was 30,740 mg / L. Similarly, similar tests were conducted for EM-3 and DI-1. The results are shown in Table 2.

(Comparative Example 1)
A water-in-oil emulsion EM-1 was fed at a rate of 2 L / min for 12.5 minutes while charging 5 m ³ of tap water into a polymer flocculant dilution tank equipped with a stirrer shown in the dilution system flow of FIG. A 2% by weight dilution was prepared. After preparing a diluted solution by stirring for 1 hour, using the same sewage mixed raw sludge as used in Example 1, the sludge was supplied to the sludge agglomeration mixing tank at 11 m ³ / hr, and the 0.2% by weight dilution was performed. The liquid was supplied to the sludge coagulation mixing tank at 183 L / hr (corresponding to an addition amount of 0.3% by mass with respect to ss). This agglomerated sludge was concentrated using a belt type concentrator (not shown) and transferred to a concentrated sludge storage tank. The sludge after concentration was 29,300 mg / L.
Similarly, similar tests were conducted for EM-3 and DI-1. The results are shown in Table 2.

Since the diluted liquid was prepared by stirring for 1 hour, the physical properties of the polymer flocculant were presumed to be slightly deteriorated, and the flocculation effect was reduced compared to the diluted liquid that was diluted in the line and used as it was for sludge treatment. It can be seen that the concentration has decreased.

(Table 2)
SS content in desorption water: mg / L, cake water content: mass%, chemical injection amount: ss mass%

A sludge treatment test was conducted using a dilution / concentration / dehydration system as shown in FIG. The dilution water supply pump 2 is operated, dilution water is supplied at a rate of 20 L / min from a water tank (not shown) through the dilution water pipe 1, and from the dispersion type polymer flocculant stock solution tank (not shown) through the pipe 8. The dispersion type polymer flocculant stock solution supply pump 9 was operated, and the water-in-oil emulsion EM-1 was supplied at a rate of 100 mL / min. The diluting water passes through the diluting water flow rate adjusting valve 4 and the nozzle 5 having a function of generating turbulent flow, and at the T-shaped joint 6, the diluting water is combined with the dispersed polymer flocculant stock solution that has passed through the check valve 10 and mixed.・ Dilution is performed, and almost dilution is performed in the line mixer 7,
It is supplied to the centrifugal concentrator 15. Sludge supply 11 is performed, and aggregation and concentration operations are performed.

The same operation as in Example 1 is performed. Using the sewage surplus sludge (pH 6.48, ss content 10,300 mg / L), the sludge is supplied to the centrifugal concentrator 15 at 11 m ³ / hr. In addition, dilution water is supplied from the water tank at a rate of 40 L / min, and water-in-oil emulsion EM-2 is supplied from the stock solution tank at a rate of 200 mL / min, so that 40% by mass of the stock solution is reduced to 0.19% by mass. Each pump was set to dilute. The water-in-oil emulsion EM-2 diluted solution discharged from the line mixer was supplied to the centrifugal concentrator 15 at a rate of 30.5 L / hr to the sludge flocculation mixing tank (to an addition amount of 0.05 mass% relative to the ss). Equivalent). It was supplied, concentrated, and transferred to a concentrated sludge storage tank. The concentration of sludge after concentration was 28,800 mg / L. Similarly, the same test was conducted on EM-4 and EM-5. The results are shown in Table 3.

(Comparative Example 2)
A 5 g ³ tap water is charged into a polymer flocculant dilution tank equipped with a stirrer shown in the dilution system flow of FIG. 1, and a water-in-oil emulsion EM-2 is supplied at a rate of 2 L / min for 12.5 minutes. A 19% by weight dilution was prepared. After preparing the diluted solution, the same sludge mixed raw sludge as used in Example 1 was used, the sludge was supplied to the centrifugal concentrator 15 at 11 m ³ / hr, and the water-in-oil emulsion discharged from the line mixer. The EM-2 diluted solution was supplied to the sludge agglomeration mixing tank at 30.5 L / hr (corresponding to an addition amount of 0.05 mass% with respect to ss), concentrated, and transferred to a concentrated sludge storage tank. The concentration of sludge after concentration was 27,800 mg / L. Similarly, the same test was conducted on EM-4 and EM-5. The results are shown in Table 3.

Since the diluted liquid was prepared by stirring for 1 hour, the physical properties of the polymer flocculant were presumed to be slightly deteriorated, and the flocculation effect was reduced compared to the diluted liquid that was diluted in the line and used as it was for sludge treatment. It can be seen that the concentration has decreased.

(Table 3)

SS content in desorption water: mg / L, cake water content: mass%, chemical injection amount: ss mass%

It is a system diagram for preparing a diluting solution of a dispersion type polymer flocculant, supplying the sludge and diluting solution to a sludge coagulating tank, and then performing concentration and sludge dewatering by a belt concentrator. It is a system diagram for preparing a dilute solution of a dispersion type polymer flocculant, supplying sludge and dilute solution to a centrifugal concentrator, and then performing mechanical concentration and sludge dewatering.

1 Dilution water 2 Dilution water supply pump 3 Flow meter 2
4 Dilution water flow control valve 5 Nozzle having a function of generating turbulent flow 6 T-shaped joint 7 Line mixer 8 Dispersive polymer flocculant 9 Dispersive polymer flocculant supply pump 10 Check valve 11 Sludge supply 12 Sludge Coagulation mixing tank 13 Batch type polymer flocculant dilution tank 14 After coagulation treatment, transfer to belt concentrator and then to sludge dehydrator 15 Centrifugal concentrator,
16 Transfer to sludge dehydrator

Claims (8)

Dispersing polymer flocculant and diluting water are supplied to a pipe, brought into contact with the pipe, mixed and prepared, and the diluted liquid is supplied to a concentrator in a sludge treatment facility to perform a coagulation operation and a concentration operation. To treat sewage sludge. The method for treating sewage sludge according to claim 1, wherein the concentrator is a centrifugal concentrator. The method for treating sewage sludge according to claim 1, wherein the dilution liquid is supplied to a sludge flocculation mixing tank, and after a flocculation operation, the dilution liquid is transferred to a belt concentrator and concentrated. A T-shaped joint is used as a means for bringing the dispersion-type polymer flocculant and the dilution water into contact with each other in the pipe, and from the portion where the dispersion-type polymer flocculant and the dilution water contact with respect to the flow direction of the dilution water. The sewage sludge treatment method according to claim 1 or 3, wherein a nozzle having a function of increasing a flow rate of dilution water and generating a turbulent flow is installed at a position of 10 mm or more and 100 mm or less. The method for treating sewage sludge according to claim 4, wherein the nozzle is a wing nozzle. 5. The sewage sludge according to claim 4, wherein a check valve is installed in a pipe of the dispersed polymer flocculant within 200 mm from the point where the dispersed polymer flocculant and the dilution water come into contact. Processing method. The method for treating sewage sludge according to claim 1 or 3, wherein the dispersed polymer flocculant is a water-in-oil polymer emulsion. From the water-in-oil emulsion, a copolymer of one or two selected from a hydrophobic monomer, a cationic monomer, an anionic monomer, and a monomer having a polyoxyethylene chain The method for treating sewage sludge according to claim 7, wherein an oil-soluble polymer is blended.