JPH0359760B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] This invention relates to a method for flocculating organic sludge, and more specifically, by adding specific inorganic and organic flocculants to organic sludge and granulating it, it is possible to obtain a highly processed sludge. The present invention relates to a method for agglomerating organic sludge that can easily produce granules. [Prior Art] A large amount of organic sludge is generated from treatment plants for human waste, sewage, organic wastewater, etc. Conventionally, inorganic metal salts and cationic polymer flocculants have been used to flocculate such organic sludge. Furthermore, as a general sludge treatment method, a method has been proposed in which a metal salt and an organic polymer flocculant are added under conditions where the two react and granulation is carried out (Patent No. 1070602). [Problems to be solved by the invention] Although these conventional techniques are effective to some extent, in the former method, depending on the type of sludge, the metal salt may not be able to be used as a cationic polymer flocculant alone. The flocculating effect was not sufficient, and even if an attempt was made to dehydrate the aggregates, dehydration was sometimes difficult. In addition, the latter granulation method also produces good results when the target sludge is inorganic, but in the case of organic sludge like the one used in the present invention, the strength of the aggregates is not sufficient. Therefore, there was a problem in that even if this aggregate was dehydrated, satisfactory results could not be obtained. Furthermore, a relatively preferable method that has recently been proposed is a method using an acrylic acid hydrazide polymer compound for dewatering sludge (Japanese Patent Application Laid-open No. 36697/1983). However, even with this method, the sludge flocs are still fine and gravity separation is insufficient.
Another disadvantage is that the moisture content of the dehydrated cake is high. Even if heavy metal ions such as iron and manganese are used in combination with the polymer compound, the above-mentioned drawbacks cannot be sufficiently overcome. [Means for Solving the Problems] This invention has been carried out to solve the problems of the above-mentioned prior art.After adding and stirring a metal salt of organic sludge, acrylic acid is further added. This is an organic sludge flocculation method characterized by adding a hydrazine polymer compound and a cationic polymer compound containing an amino group or a quaternary ammonium salt and granulating it. The organic sludge that is the subject of this invention includes anaerobic digested sludge of human waste, aerobic digested sludge of human waste, human waste septic tank sludge, surplus sludge generated from activated sludge treatment of sewage and various industrial wastewater, and first-settled sludge of sewage. , tertiary treatment coagulated sludge of human waste, sewage, etc., coagulated sludge of various organic wastewaters, mixed sludge of these, and biological dephosphorization sludge by activated sludge method of human waste, sewage, industrial wastewater, etc. It is not limited. In this invention, a metal salt is first added to such organic sludge. The metal salt to be added is preferably an aluminum or iron salt, and an aluminum salt is particularly preferred from the viewpoint of handling. As the aluminum salt, aluminum chloride, aluminum sulfate, and polyaluminum chloride (PAC) are suitable. When using iron salts, ferric chloride, ferrous chloride, ferrous sulfate, ferric sulfate,
Polyferric sulfate and the like are preferred. After adding such a metal salt, stirring is performed, but the purpose is to bring the added metal salt and organic sludge into sufficient contact and cause a reaction, and stirring may be performed using a stirring blade in a stirring tank. , or may be due to the flow in the piping. In the former case, stirring is usually carried out at a circumferential speed of about 40 to 120 m/min with a residence time of 2 minutes or more. In this invention, the preferable addition amount of the metal salt is 0.1 to 10 wt.% as metal based on the SS of the sludge.
Particularly preferably 1.0 to 3.0 wt.%. To the organic sludge thoroughly mixed and stirred with the metal salt in this manner, an acrylic acid hydrazide polymer compound and a cationic polymer compound containing an amino group or a quaternary ammonium salt are subsequently added and granulated. The acrylic acid hydrazide polymer compound (hereinafter referred to as AH polymer) used in the present invention has the general formula (In the formula, R represents H or _CH3 , A represents a monomer unit of acrylamide, methacrylamide, acrylic ester, methacrylic ester, and B represents acrylic acid or a salt thereof, methacrylic acid or a salt thereof, or the above-mentioned Preferably, the compound represents a monomer unit copolymerizable with A, and l, m, and n have the following relationship: 0 mol%<l≦100 mol%, n+m+l=100 mol%. Examples of the B unit copolymerizable with the A unit include vinyl chloride, vinyl acetate, butadiene, styrene, acrylonitrile, and the like. The polymerization form of AH polymer is block type.
It may be either an alternating type or a random type. Further, the intrinsic viscosity of the AH polymer is preferably [η] ³⁰ °C _1N - _NaNO3 >0.1 (dl/g). An example of the production of AH polymer is shown below, but the method for producing AH polymer is described in Japanese Patent Application Laid-Open No.
-Details are disclosed in Publication No. 144004. Examples of the polymer compound containing an amino group or a quaternary ammonium salt (hereinafter referred to as AA polymer) used in the present invention include aminoalkyl acrylates such as dimethylaminoethyl acrylate, aminoalkyl methacrylates such as dimethylaminoethyl methacrylate, Examples include aminoalkylacrylamides such as dimethylaminopropylacrylamide, aminoalkylmethacrylamides such as dimethylaminopropylmethacrylamide, and quaternized products thereof. Also,
Copolymers of these and other copolymerizable monomers can also be used, such as acrylamide,
Examples include methacrylamide acrylonitrile, methacrylonitrile, vinyl acetate, acrylic ester, and methacrylic ester. The intrinsic viscosity of the AA polymer is [η] ³⁰ °C _0.1N - Desirably _NaCl is 5 dl/g or more. The usage ratio of AH polymer and AA polymer is
Weight ratio of 1:9 to 9:1, preferably 2:8 to
The ratio is 8:2. The amount of these polymers added is preferably 0.3 to 5.0% in total based on the SS of the sludge. As for the method of adding the AH polymer and the AA polymer, they may be made into aqueous solutions in advance in separate containers and then made into one liquid before use, or they may be added separately and simultaneously. Furthermore, both powders may be added to the same container, made into an aqueous solution, and then added. However, when converting these polymers into one liquid, AH
Hydrolysis of the polymer often produces acrylic acid or methacrylic acid, and if the amount of these produced increases, a reaction between the AH polymer and the AA polymer will occur, and sufficient effects will not necessarily be obtained. Therefore, it is desirable to prevent the reaction between the AH polymer and the AA polymer by making the liquid containing both polymers contain an acid, an acidic salt, or an alkali or an alkaline salt to adjust the pH to 3 or lower or 9 or higher. Such acids or acidic salts include HCl,
Examples of alkali or alkaline salts include H ₂ SO ₄ , sulfamic acid, NaHSO ₄ , etc.
Examples include NaOH, KOH, NH ₄ OH, Na ₂ CO ₃ and the like. In addition, the effect can be similarly improved by using alkaline earth metal ions, which are neutral salts such as CaCl ₂ , MgCl ₂ , and BaCl ₂ . In this way, the organic sludge to which the acrylic acid hydrazine polymer compound and the cationic polymer compound containing amino groups or quaternary ammonium salts are added is granulated, and the granulation is carried out using a stirrer. Perform in a stirring tank. The stirring conditions are such that the circumferential speed of the stirring blade is 25 to 250 m/min and the residence time is about 3 to 30 minutes. If the conditions deviate from this range, favorable results will not be obtained. Note that the polymer compound may be added before the organic sludge is supplied to the stirring tank, or may be added directly into the stirring tank. In this way, granular aggregates of organic sludge are obtained, and these aggregates may be fed to a dehydrator, dehydrated, and then disposed of. Dewatering is carried out by known means such as a belt press type dehydrator, centrifugal dehydrator, rotary screen/roll press, screw press, filter press, etc. [Function] By thoroughly mixing and stirring the organic sludge with the metal salt, the negative charge of the organic sludge is neutralized by the metal salt, and the organic sludge is made hydrophobic, forming minute flocs. Next, an acrylic acid hydrazide polymer compound and a cationic polymer compound containing an amino group or a quaternary ammonium salt are added and granulated, so that the micro flocs and these polymer compounds react. As a result, the flocs become coarser and grow to form strong granular aggregates. Note that flocs are brittle aggregates with irregular shapes, but granules here are strong granular aggregates with a fixed particle size distribution, and they differ widely in appearance and physical properties. It is something to do. Next, the effects of the present invention will be specifically explained using manufacturing examples and examples. The Preparation Example is an example of the preparation of the AH polymer used in the Examples. Polymethyl acrylate in the 4-necked flask of Production Example 3
Add 200g and 2kg of hydrazine hydrate aqueous solution,
The reaction was carried out at 80° C. for 5 hours while stirring. The resulting viscous solution was poured into about 20 methanol to obtain a white precipitate. This was taken, purified by a reprecipitation method, and then dried under reduced pressure at 60°C to obtain an acrylic acid hydrazide polymer compound (hereinafter referred to as A). Intrinsic viscosity of A [η] ³⁰ °C _1N - _NaCl was 2.5 dl/g, and colloid equivalent was -1.7 meq/g (PH10.5). When the composition of the polymer was determined in conjunction with the results of iodometric titration, it was found that acrylic acid hydrazide-methyl acrylate-acrylic acid hydrazine salt = 70/15/15 (molar ratio). [Example of the Invention] The method of the invention was carried out on surplus sewage sludge exhibiting properties of PH6.8, SS1.1%, and VSS69%/SS. First, the above surplus sludge is supplied to a coagulation tank equipped with stirring blades that rotates at a circumferential speed of 63 m/min.
PAC was added at 4.5% (relative to SS, the same applies hereinafter) and allowed to stay for 4 minutes. Next, the effluent from the coagulation tank was supplied to a granulation tank equipped with stirring blades rotating at a circumferential speed of 41 m/min, and a predetermined amount of the polymer compound composition shown in the table was added to this granulation tank. It was allowed to stay for a minute. Thereafter, the particle size of the flocculated granular sludge was measured, and then 200 ml of this flocculated sludge was collected and subjected to a dewatering test. The dehydration test was conducted on the liquid volume after 10 seconds and the water content of the dehydrated cake. The former method involves injecting flocculated sludge into a Buchner funnel lined with 100 mesh nylon cloth and determining the amount of liquid after 10 seconds. The latter was passed through a Buchner funnel for 1 minute, and then the sludge was passed through a belt press type dehydrator cloth (made of polyester,
The water content of the dehydrated cake was measured after it was squeezed between a sponge and a sponge and compressed for 60 seconds at a pressure of 3.0 kg/cm ² . For comparison, when inventive example No. 1 was agglomerated under the same conditions except that the residence time in the granulation tank was 2 minutes (No. 3), the polymer A (No. 3) was agglomerated.
4), the case where only B (No. 5) was added was also carried out. The results are shown in the table. From this table, it can be seen that according to the method of this invention, extremely good granular aggregates can be obtained, and the dehydration properties thereof are also extremely good. In addition, even if the same drug is used, if the granulation time is shortened, granular aggregates cannot be obtained, and even if the stirring conditions are the same, granular aggregates cannot be obtained with the combination of drugs according to the conventional method. It can be seen that in both cases, the dehydration properties are also extremely poor.

【table】

〔Effect of the invention〕

In this invention, by adding a combination of a metal salt and a specific polymer compound to organic sludge and granulating it, granular aggregates with extremely good properties can be obtained even with organic sludge. In addition, the granular aggregates have extremely high dehydration properties,
Compared to conventional methods, moisture content etc. can be greatly improved.

Claims (1)

[Claims] 1. After adding a metal salt to organic sludge and stirring, an acrylic acid hydrazide polymer compound and a cationic polymer compound containing an amino group or a quaternary ammonium salt are further added. A method for agglomerating organic sludge, which is characterized by granulating the organic sludge. 2 Acrylic acid hydrazide polymer compound has the general formula (In the formula, R represents H or _CH3 , A represents a monomer unit of acrylamide, methacrylamide, acrylic ester, methacrylic ester, and B represents acrylic acid or a salt thereof, methacrylic acid or a salt thereof, or the above-mentioned A represents a monomer unit copolymerizable with , and l, m and n have the following relationship: 0 mol%<l≦100 mol% n+m+l=100 mol%) according to claim 1. Method for flocculating organic sludge. 3. Claims in which the cationic polymer compound containing an amino group or a quaternary ammonium salt is a compound selected from aminoalkyl acrylate, aminoalkyl methacrylate, aminoalkyl acrylamide, aminoalkyl methacrylamide, or quaternized products thereof. The method for flocculating organic sludge according to item 1 or 2. 4. The method for aggregating organic sludge according to any one of claims 1 to 3, wherein the metal salt is an aluminum or iron salt.