JP3458455B2 - Sludge dewatering method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial sludge containing 0.3% or more of a soluble inorganic salt in organic sludge, domestic wastewater such as human waste and sewage, and a chemical plant / organic sludge. The present invention relates to a method for dewatering sludge generated from wastewater from a dyeing and sorting factory. 2. Description of the Related Art A polymer flocculant is used for dehydration of excess sludge generated from sewage, night soil, and industrial wastewater, but sludge from a treatment plant using seawater as a diluting water for sludge is used. However, sludge having a high concentration of soluble inorganic salts has a drawback that conventional polymer flocculants do not form sufficient flocs and cannot be dewatered. It has been reported that the use of a quaternized benzyl halide polymer flocculant in such sludge is effective (Japanese Patent Application Laid-Open No. 54-121557), and is still widely used. [0003] Seawater is used as a diluting water for the sludge, and sludge from a treatment plant where seawater flows in, such as a seaside treatment plant, and a chemical plant and a dyeing and sorting plant are formed of soluble inorganic salts. It is considered that the concentration is high, and even if a polymer flocculant is added, the polymer is considered to be in a yarn ball state due to the effect of the soluble inorganic salts in the sludge, and thus often does not have sufficient performance as a flocculant. The present inventors have conducted intensive studies with the aim of solving such a problem, and as a result, have reached the present invention. According to the present invention, a polyfunctional monomer is used in an amount of 0.0005 wt% to 0.0
A sludge dewatering method characterized in that a polymer obtained by adding and polymerizing in a range of 03 wt% is added to sludge containing 0.3% or more of soluble inorganic salts in organic sludge, and flocs are formed and dewatered. When a polymer flocculant is added to sludge diluted with seawater containing soluble inorganic salts, it is considered that the polymer is likely to become thread-yellow due to the effect of the soluble inorganic salts in the sludge. It is considered that sufficient cohesiveness is not obtained. [0007] However, in the case of a polymer obtained by adding a polyfunctional monomer and polymerizing, even if it is added to a sludge containing soluble inorganic salts, it is possible to prevent or reduce the formation of thread and to form a floc sufficient for a dehydration treatment. It is considered something. Hereinafter, the present invention will be described in detail. The cationic vinyl polymer used in the present invention includes one or more nonionic vinyl monomers.
A copolymer obtained by adding one or more polyfunctional monomers to one or more kinds of cationic vinyl monomers and one or more kinds of cationic vinyl monomers, and a cationic vinyl monomer 1
There is a copolymer obtained by adding one or more kinds of polyfunctional monomers to the kind or two or more kinds and polymerizing them. Further, one or more nonionic monomers are added to one or more polyfunctional monomers to form a copolymer obtained by polymerization, and then the functional groups are modified. A method of finally forming a cationic polymer may be used. For example, there is a method in which methylenebisacrylamide is added in advance to polymerize acrylamide to obtain polyacrylamide, and then the resulting polymer is converted into a cationic polymer by a Mannich reaction, a Hoffman decomposition reaction, or the like. As the vinyl monomers used in the present invention, (a) nonionic, (b) cationic and water-soluble monomers are used. Specific examples are as follows. (A) Nonionic vinyl monomers (meth) acrylamide, vinyl methyl ether, vinyl ethyl ether and the like. (B) Cationic vinyl monomer (1-A), (2-A), (3-A), (4
-Selected from the group of A). (1-A) Quaternary nitrogen-containing (meth) acrylate [(meth) acrylate refers to acrylate and methacrylate. The same applies hereinafter. (I) (meth) acryloyloxyalkyltrialkylammonium salts such as 2- (meth) acryloyloxyethyltrimethylammonium chloride;
2- (meth) acryloyloxyethyltrimethylammonium methosulfate, 2- (meth) acryloyloxyethyltriethylammonium ethosulfate, 3
-(Meth) acryloyloxypropyldimethylethylammonium methosulfate and the like. (Ii) (meth) acryloyloxyhydroxyalkyltrialkylammonium salt such as 3-
Methacryloyloxy-2-hydroxypropyltrimethylammonium chloride, 3-methacryloyloxy-2
-Hydroxypropylmethyldiethylammonium chloride, 3-methacryloyloxy-2-hydroxypropyltrimethylammonium methosulfate and the like. (2-A) Salt of tertiary nitrogen-containing (meth) acrylate and acid (i) dialkylaminoalkyl (meth)
Acrylate salts such as 2-dimethylaminoethyl (meth) acrylate sulfate, 2-diethylaminoethyl (meth) acrylate hydrochloride, and the like. (Ii) Salts of dialkylaminohydroxyalkyl (meth) acrylates such as 3-dimethylamino-2-hydroxypropyl (meth) acrylate hydrochloride, 3-diethylamino-2-hydroxypropyl (meth) acrylate sulfate and the like. (3-A) Quaternary nitrogen-containing (meth) acrylamide (i) (meth) acrylamidoalkyltrialkylammonium salt such as 3-acrylamidopropyltrimethylammonium chloride, 2- (meth) acryloylaminoethyltrimethyl Ammonium methosulfate and the like. (Ii) (meth) acrylamido hydroxyalkyltrialkylammonium salts such as 3-
(Meth) acryloylamino-2-hydroxylpropyltrimethylammonium chloride, 3- (meth) acryloylaminoethyltrimethylammonium methosulfate and the like. (4-A) Salt of tertiary nitrogen-containing (meth) acrylamide and acid (i) dialkylaminoalkyl (meth)
Acrylamide salts such as 2-dimethylaminoethyl (meth) acrylamide hydrochloride, 2-diethylaminopropyl (meth) acrylamide sulfate and the like. (Ii) Salts of dialkylaminohydroxyalkyl (meth) acrylamide such as 3-dimethylamino-2-hydroxypropyl (meth) acrylamide acetate, 3-diethylamino-2-hydroxypropyl (meth) acrylamide sulfate and the like. Further, as the polyfunctional monomer, N,
Divinyl compounds such as N'-methylenebisacrylamide, N, N'-methylenebismethacrylamide, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, divinylbenzene, and vinyl-based methylol compounds such as methylol methacrylamide And vinyl compounds such as vinyl aldehyde compounds such as acrolein and methyl acrylamide glycolate methyl ether. The polyfunctional monomer of the polymer used in the present invention is 0.000 to the total amount of the water-soluble vinyl monomer.
It is blended and copolymerized at a ratio of 5 to 0.003 wt%. When the amount of the polyfunctional monomer is less than 0.0005% by weight, only an effect equivalent to that of a commonly used polymer flocculant can be obtained, and when the amount exceeds 0.003% by weight, the amount added to the sludge becomes excessive. In a practical range of the addition amount, the effect is not recognized. The cationic vinyl polymer used in the present invention has a degree of cation (measurement method for cationic polymer flocculant physical properties and analysis method-3, according to Polymer Flocculant Industry Association) of 1 meq.
/ G or more, preferably 1.5 meq / g or more is particularly effective. The soluble inorganic salts contained in the sludge are mainly alkali metal and alkaline earth metal salts.
Examples include potassium chloride, sodium chloride, calcium chloride, magnesium chloride, ammonium chloride, potassium sulfate, sodium sulfate, calcium sulfate, ammonium sulfate, sodium nitrate, potassium nitrate and the like. In the sludge, one of these soluble inorganic salts is contained.
Seeds or two or more kinds may be contained. The concentration of the soluble inorganic salts was measured as follows. Put 50ml of sludge in a sedimentation tube and 3000rpm
After centrifugation for 10 minutes, the supernatant was removed and
Dry at 05 ° C to 110 ° C for 2 hours. Further, at 600 ° C. ± 25 ° C. in an electric furnace for 30 to 4 hours.
The mixture is heated for 0 minutes, allowed to cool in a desiccator, weighed, and the amount of the soluble inorganic salt in the sludge is measured. The concentration of the soluble inorganic salts in the sludge is particularly 0.3
% Or more is effective in practicing the method of the present invention. When the amount is less than 0.3%, it is often possible to treat with a usual chemical or flocculant. When the amount is more than 0.3%, dehydration becomes extremely difficult as described above, but the polymer of the present invention is used. Thus, dehydration can be easily performed. The upper limit of the concentration of the soluble inorganic salt is not particularly limited, and the dehydration can be carried out without any practical problem until the precipitation of the salt. The polymer used in the present invention can be copolymerized by a commonly used known polymerization method. In particular, a method of copolymerizing the water-soluble vinyl monomer and a small amount of a polyfunctional monomer in a hydrophobic surfactant and an organic solvent is preferable. If necessary, a chain transfer agent, a chelating agent and the like can be used. The polyfunctional monomer may be added at any time before, during or after the polymerization. For example, an aqueous solution containing a water-soluble vinyl monomer and a polyfunctional monomer and an organic dispersion medium containing a hydrophobic surfactant having an HLB of 3 to 6 are mixed and emulsified. There is a method of producing a water-in-oil cationic polymer emulsion by polymerizing at a temperature of 30 to 80 ° C (Japanese Patent Application No. 61-236250). A hydrophilic surfactant is added to this water-in-oil type emulsion, mixed with water, and phase-inverted into an oil-in-water type emulsion for use. The method for obtaining the cationic polymer of the present invention is as follows:
A method in which the functional group is finally modified into a cationic polymer by modifying the functional group may be used. For example, there is a method in which acrylamide is polymerized in advance to obtain polyacrylamide, and then this is converted into a cationic polymer by a Mannich reaction, a Hoffman decomposition reaction, or the like. The polymer used in the present invention may be in the form of a powder or a liquid such as an emulsion or a suspension, but an emulsion having good water dispersibility is preferred. Next, such a polymer is added to a sludge containing 0.3% or more of a soluble inorganic salt, and the mixture is stirred and mixed to obtain a tight hard floc. The method of adding, stirring and mixing the polymer to the sludge is not specified because it varies depending on the conditions of the sludge to be treated. 0.1 wt% or more and 5 wt% or less, preferably about 2 to 0.3 wt%, of a polymer active ingredient is added to the product (according to the sewer test method), and the mixture is rapidly stirred for a short time to form flocs, which are then dehydrated. And the like. Hereinafter, the present invention will be described more specifically with reference to examples. EXAMPLES AND COMPARATIVE EXAMPLES 300.0 g of methyl quaternary chloride of dimethylaminoacrylate (DMAEA), 100.0 g of acrylamide (AMD), and 0 g of methylenebisacrylamide (MBA) (Sample A,
0 wt%), 0.004 g (Sample B, 0.0
01 wt%), 0.01 g (Sample C, 0.0
025 wt%), 0.02 g (Sample D, 0.
005 wt%) in 307 g of distilled water.
15.4 g of a nonionic surfactant having an LB of 4.2 was poured into 204.7 g of paraffin oil, and emulsified with a homogenizer. This was degassed with nitrogen gas, and a water-soluble azo catalyst was added for polymerization. 239.0 g of methyl quaternary chloride of dimethylaminoacrylate (DMAEA), 160.0 g of acrylamide (AMD), and 0 g of methylenebisacrylamide (MBA) (Sample E, 0 wt.
%), 0.004 g (Sample F, 0.001w)
t%), 0.01 g (Sample G, 0.0025
wt%), 0.02 g (Sample H, 0.005
wt%) is dissolved in 307 g of distilled water.
15.4 g of 4.2 nonionic surfactant was poured into 204.7 g of paraffin oil and emulsified by a homogenizer. This was degassed with nitrogen gas, and a water-soluble azo catalyst was added for polymerization. Dimethylaminoacrylate (DMAE)
An aqueous solution prepared by dissolving 239.0 g of a benzyl chloride quaternary product of A) and 160.0 g of acrylamide (AMD) in 307 g of distilled water was used as a nonionic surfactant 1 having an HLB of 4.2.
5.4 g was poured into 204.7 g of paraffin oil and emulsified with a homogenizer. This was degassed with nitrogen gas, and a water-soluble azo catalyst was added for polymerization (Sample I). Excess sludge (TS (evaporation residue): 3.73%, activated sludge) containing 0.8% of soluble inorganic salts, which was collected from a human wastewater treatment plant in which these polymers were diluted with seawater.
(Floating substance) 2.47%, VTS (Ignition loss of evaporation residue) 59.7%, VSS (Ignition loss of floating substance) 77.
4%) and stirred with a stirrer at 1000 rpm for 30 seconds, visually compared and determined by a floc size standard chart, and then poured onto a 60 mesh screen to measure the amount of drainage after 10 seconds. Further, the sludge remaining on the screen was dewatered at 2000 rpm for 5 minutes using a centrifugal separator with a circular sedimentation tube, and the water content was measured. Table 1 shows the results. As shown in Table 1, the sludge can be efficiently dewatered according to the method of the present invention. In addition, the same effect was obtained as a result of conducting a polymerization using polyethylene glycol diacrylate instead of the methylene bisacrylamide added at the time of the above-mentioned polymerization and using it for the above-mentioned sludge. The above-mentioned polymer was treated with excess sludge (T) of activated sludge having a soluble inorganic salt concentration of 0.55% collected from a chemical plant.
S 2.14%, SS 1.75%, VTS 65.4
%, VSS 80.0%) and 1000r with a stirrer
After stirring at pm for 30 seconds, a floc size standard chart was visually compared and judged, and then poured onto a 60-mesh screen, and the drainage amount after 10 seconds was measured. Further, the sludge remaining on the screen was dewatered at 2000 rpm for 5 minutes using a centrifuge with a circular sedimentation tube, and the water content was measured. Table 2 shows the results. As can be seen from Table 2, sludge can be efficiently dewatered according to the method of the present invention. The above-mentioned polymer was treated with excess sludge (TS) of activated sludge having a soluble inorganic salt concentration of 1.8% collected from a chemical factory.
4.22%, SS 1.59%, VTS 28.09
%, VSS 70.45%) and 1000 with a stirrer.
After stirring at rpm for 30 seconds, a floc size standard chart was visually compared and judged, and then poured onto a 60-mesh screen, and the drainage amount after 10 seconds was measured. Further, the sludge remaining on the screen was dewatered at 2000 rpm for 5 minutes by a centrifuge with a circular sedimentation tube, and the water content was measured. Table 3 shows the results. [Table 1] [Table 2] [Table 3] According to the method of the present invention, sludge can be efficiently dewatered.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masuzo Machida 1190 Kasama-cho, Sakae-ku, Yokohama Mitsui Cytec, Inc. Ofuna Research Laboratory (56) References JP-A-64-85199 (JP, A) JP-A Sho JP-A-57-135099 (JP, A) JP-A-59-16599 (JP, A) JP-A-7-313999 (JP, A) JP-A-7-313997 (JP, A) A) JP-A-7-314000 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 11/12-11/14

Claims (1)

(57) [Claims 1] In a sludge containing 0.3% or more of a soluble inorganic salt, a polyfunctional monomer is added in an amount of 0.000 to the total monomer.
A sludge dewatering method characterized by adding a cationic vinyl polymer obtained by adding and polymerizing in a range of 5 wt% to 0.003 wt% to form flocs and dewatering.