JP2000126800A - Dehydration of organic sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cake low in the concn. of a suspended substance in separeated water, high in the recovery ratio thereof, high in the strength of floc and low in water content by efficiently dehydrating org. sludge containing biologically treated sludge generated from sewage, excretion or industrial waste water by the addition of a small amt. of a chemical agent. SOLUTION: In a dehydration method, a cationic org. polymeric flocculant is added to org. sludge and org. sludge and the cationic org. polymeric flocculant are reacted under a strong shearing force applied condition to dehydrate org. sludge. In this case, the cationic org. polymeric flocculant wherein inherent viscosity is 3 dl/g or more and the quotient obtained by dividing the product of the viscosity (meats) of a 0.2 wt.% aq. soln. measured at a rotational speed of 30 rpm using a Brookfield rotational viscometer and the inherent viscosity (dl/g) by the stringing length (mm) of a 0.4 wt.% aq. soln. is 50-200 is added and sludge is mechanically dehydrated by a dehydrator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for dehydrating organic sludge. More specifically, the present invention relates to a method for dehydrating organic sludge that can efficiently dehydrate organic sludge containing biologically treated sludge generated from sewage, human waste, industrial wastewater, and the like.

[0002]

2. Description of the Related Art In recent years, organic sludge including biologically treated sludge generated from municipal sewage or human waste treatment has increased the rate of addition of a dehydrating agent required for sludge dewatering due to an increase in organic matter content and decay. There is a tendency for dewatering to be difficult, for example, the water content of the dewatered cake is high, and the sludge treatment amount must be kept low. Various dehydration methods have been attempted for these hardly dewaterable sludges. For example, JP-A-63-1582
No. 00, the moisture content of the dewatered cake is low, as a method of dewatering sludge having a good filter cloth releasability, after adding an inorganic flocculant,
A method of dewatering sludge has been proposed in which an amphoteric organic polymer flocculant is added to organic sludge having a pH value of 5 to 8, and then dewatered. Japanese Patent Application Laid-Open No. 2-180700 discloses that sludge treatment capacity is large, suspended solids recovery rate is high, dewatered cake is easily separated from filter cloth, and the water content of dewatered cake is reduced. As an organic sludge dewatering method, an inorganic coagulant is added to organic sludge, and an amphoteric organic polymer coagulant having a specific colloid equivalent value and a ratio of anion amount / cation amount is added. A way to do that has been proposed. In addition, Japanese Patent Publication No. 3-4716
No. 0 discloses a method of dehydrating organic sludge in which the strength of the generated floc is large, the dewatering is easy, the water content of the cake is low, and the amount of suspended solids flowing out to the separated water is small. There has been proposed a method of performing a coagulation treatment using a metal salt such as described above and further adding a cationic polymer coagulant having a quaternary ammonium group to perform dehydration. Such a method of dehydrating by using two or more kinds of chemicals in combination is effective in improving the dehydration of hardly dewaterable sludge and has been widely used. However, these conventional techniques have problems such as high chemical cost, poor versatility in effect, and complicated equipment and work. On the other hand, as for the dewatering machine, a high-efficiency centrifugal dewatering machine with a dewatering mechanism incorporating the concept of consolidation was developed, and the Japan Sewage Works Agency issued a
It is certified by the private development technology examination certificate in fiscal year. By using this high-efficiency centrifugal dehydrator, cakes with a low moisture content are being obtained, but applicable sludge types are limited. For this reason, it can be widely applied to organic sludge including biologically treated sludge generated from sewage, night soil, industrial wastewater, etc. There has been a demand for a method for dehydrating organic sludge, which has good releasability from water and can obtain a cake having a low water content.

[0003]

DISCLOSURE OF THE INVENTION The present invention is directed to a method of efficiently dehydrating organic sludge containing biologically treated sludge generated from sewage, night soil, industrial wastewater, etc. by adding a small amount of a chemical, and removing SS from separated water. An object of the present invention is to provide a method for dehydrating organic sludge, which can obtain a cake having a low concentration, a high SS recovery rate, a high floc strength and a low moisture content.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, organic sludge has been obtained.
When the intrinsic viscosity is 3 dl / g or more, the product of the viscosity (mPa · s) of the 0.2% by weight aqueous solution and the intrinsic viscosity (dl / g) is 0.4% by weight.
By adding a cationic organic polymer flocculant whose quotient divided by the spinning length (mm) of the aqueous solution is in a specific range, reacting the sludge with the flocculant under conditions of strong shearing force, and dehydrating , Found that effective dehydration can be performed easily,
Based on this finding, the present invention has been completed. That is, the present invention relates to (1) adding a cationic organic polymer flocculant to organic sludge, reacting the organic sludge with the cationic organic polymer flocculant under conditions of strong shearing force, and dehydrating the organic sludge. Organic sludge dewatering method, the intrinsic viscosity is 3dl
/ G or more and a rotational speed of 30 using a B-type rotational viscometer.
Viscosity of 0.2 wt% aqueous solution measured at rpm (mPa · s)
And the intrinsic viscosity (dl / g) divided by the spinning length (mm) of a 0.4% by weight aqueous solution are added, and a cationic organic polymer flocculant having a quotient of 50 to 200 is added. Organic sludge dewatering method characterized in that mechanical dehydration is performed by using a homogenizer (2).
(1) which is a condition corresponding to stirring at 00 rpm for 5 seconds or more.
(3) The organic sludge dewatering method according to (1), wherein the organic sludge is organic sludge generated from sewage / human wastewater treatment or industrial wastewater, and the dehydrator is a centrifugal dehydrator. A method for dehydrating organic sludge. Further, as a preferred embodiment of the present invention, (4) a cationic organic polymer coagulant using a B-type rotational viscometer with a rotational speed of 30.
Viscosity of 0.2 wt% aqueous solution measured at rpm (mPa · s)
The method for dehydrating an organic sludge according to Item (1), wherein the quotient obtained by dividing the product of the intrinsic viscosity (dl / g) by the spinning length (mm) of the 0.4% by weight aqueous solution is 55 to 80, (5) The method for dehydrating organic sludge according to (1), wherein the cationic organic polymer flocculant is a copolymer of a cationic vinyl monomer and a nonionic vinyl monomer, (6) a cationic organic polymer flocculant Is a copolymer of a cationic vinyl monomer, an anionic vinyl monomer and a nonionic vinyl monomer, (7) a cationic vinyl monomer as a cationic organic polymer flocculant, The ratio of the units is 30 to 80 mol% of the total monomer units.
(5) The method for dehydrating organic sludge according to item (6) or (6), wherein (8) the centrifugal dehydrator is a high-efficiency centrifugal dehydrator.
The method of dewatering organic sludge described in the item (3) can be mentioned.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention comprises adding a cationic organic polymer flocculant to organic sludge and reacting the organic sludge with the cationic organic polymer flocculant under conditions of strong shearing force. In the method of dewatering organic sludge,
The intrinsic viscosity is 3 dl / g or more, and the product of the viscosity (mPa · s) of the 0.2% by weight aqueous solution and the intrinsic viscosity (dl / g) measured at a rotation speed of 30 rpm using a B-type rotational viscometer is 0. A cationic organic polymer flocculant having a quotient of 50 to 200 divided by the spinning length (mm) of a 0.4% by weight aqueous solution is added, and mechanically dewatered using a dehydrator. Examples of the cationic organic polymer flocculant used in the method of the present invention include a cationic vinyl copolymer obtained from a cationic vinyl monomer and a nonionic vinyl monomer, and a cationic vinyl copolymer obtained from a cationic vinyl monomer, an anionic vinyl monomer and a nonionic vinyl monomer. And the like. The cationic vinyl monomer for obtaining such a cationic organic polymer flocculant is not particularly limited, and examples thereof include a monomer represented by the general formula [1].

Embedded imageIn the general formula [1], R¹Is a hydrogen or methyl group
R^TwoRepresents a methylene group, an ethylene group, a propylene group,
An alkylene group having 1 to 4 carbon atoms such as a tylene group;
Even if the propylene group and the butylene group are linear,
You may have. R^ThreeAnd R^FourIs a methyl group, d
Tyl group, n-propyl group, isopropyl group, n-butyl
Group, isobutyl group, sec-butyl group, tert-butyl group
Any alkyl group having 1 to 4 carbon atoms;^FiveIs hydrogen, charcoal
It is an alkyl group or a benzyl group having a prime number of 1 to 4. Also,
A is -O- or -NH-, and X is^-Is chlorine ion, smell
Halogen ion such as elementary ion and iodine ion, 1/2
SO_Four ^2-, NO_Three ^-, CH_ThreeCOO ^-, CH_ThreeSO_Four ^-, C_TwoH_Five
SO_Four ^-And negative ions.

Examples of the monomer represented by the general formula [1] include dimethylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, diethylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, di-n -Propylamino
(Methyl, ethyl, propyl or butyl) acrylate or methacrylate, diisopropylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, di-n-butylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, di-sec -Butylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, diisobutylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, dimethylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, diethylamino (methyl , Ethyl, propyl or butyl) acrylamide or methacrylamide,
Di-n-propylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, diisopropylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, di-n-butylamino (methyl, ethyl, propyl or butyl) ) Acrylamide or methacrylamide, di-sec-butylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, diisobutylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, hydrogen halide, sulfuric acid, Examples include neutralized salts with nitric acid and acetic acid, and quaternized compounds with alkyl halide, benzyl halide, dimethyl sulfate, diethyl sulfate and the like. Examples of the hydrogen halide include hydrogen chloride and hydrogen bromide, and examples of the alkyl halide include methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, and ethyl iodide. Examples of benzyl bromide include benzyl chloride and benzyl bromide. One of these cationic vinyl monomers can be used alone, or two or more can be used in combination.

The nonionic vinyl monomer used in the synthesis of the cationic organic polymer flocculant includes, for example, amides such as acrylamide, methacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, acrylonitrile, methacrylic acid and the like. Vinyl cyanide compounds such as lonitrile, alkyl esters of (meth) acrylic acid such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinyl esters such as vinyl acetate, styrene, α-methyl Examples thereof include aromatic vinyl compounds such as styrene and p-methylstyrene. One of these nonionic vinyl monomers can be used alone, or two or more can be used in combination. In the method of the present invention, examples of the anionic vinyl monomer used in the synthesis of the amphoteric vinyl copolymer which can be used as the cationic organic polymer flocculant include, for example, unsaturated monohydric acids such as acrylic acid, methacrylic acid and α-ethylacrylic acid. Examples thereof include carboxylic acids and their sodium, potassium, and ammonium salts, and unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, and their sodium, potassium, and ammonium salts. One of these anionic vinyl monomers can be used alone, or two or more can be used in combination. The method for producing the cationic organic polymer flocculant used in the method of the present invention is not particularly limited, and any of ordinary methods such as solution polymerization, suspension polymerization, and emulsion polymerization can be used. In aqueous solution polymerization, after dissolving the monomer in water, replacing the atmosphere with an inert gas, and raising the temperature to the polymerization temperature, ammonium persulfate, potassium persulfate, and 2,2 ′ are used as polymerization initiators.
Polymerization can be carried out by adding a water-soluble polymerization initiator such as azobis (2-amidinopropane) dihydrochloride.

In the method of the present invention, a small amount of a cationic organic polymer flocculant having a crosslinked structure can be used. Cationic organic polymer flocculant having a cross-linked structure,
In the synthesis, it can be produced by adding a covalent crosslinking agent to the monomer mixture. Such covalent cross-linking agents include diethylenically or polyethyleneically unsaturated monomers commonly used to provide cross-linking to the water-soluble polymer, such as methylene bisacrylamide. The amount of the covalent crosslinking agent to be added is preferably a trace amount of 100 ppm or less. In the cationic organic polymer flocculant used in the method of the present invention, the ratio of cationic vinyl monomer units is preferably 30 to 80 mol% of all monomer units, and is preferably 40 to 80 mol%.
More preferably, it is about 70 mol%. The proportion of the cationic vinyl monomer unit is 30 mol% of all the monomer units.
If it is less than 30, the gravity filterability becomes poor, the water content of the cake and the SS concentration of the separated water increase, and sometimes flocculent flocs may not be formed. If the proportion of the cationic vinyl monomer unit exceeds 80 mol% of all monomer units, the gravity filterability becomes poor, and the water content of the cake and the SS concentration of the separated water may increase. In the method of the present invention, the intrinsic viscosity of the cationic organic polymer flocculant is 3 dl.
/ G or more, more preferably 4 dl / g or more,
More preferably, it is 5 dl / g or more. When the intrinsic viscosity of the cationic organic polymer flocculant is less than 3 dl / g, the flocculence is weak, the filterability is poor, and the dehydration ability is insufficient,
The water content of the cake may not be sufficiently reduced. In the method of the present invention, the intrinsic viscosity of the cationic organic polymer flocculant is determined by using a 1N aqueous solution of sodium nitrate as a solvent.
This is a value measured at 0 ° C. The intrinsic viscosity is pH 4 when the cationic organic polymer flocculant is a copolymer of a cationic vinyl monomer and a nonionic vinyl monomer.
When the cationic organic polymer flocculant is a copolymer of a cationic vinyl monomer, an anionic vinyl monomer and a nonionic vinyl monomer, the pH is preferably measured at pH 3.

In the method of the present invention, a rotational speed of 30 rpm is measured using a cationic organic polymer flocculant B-type rotational viscometer.
The product of the viscosity (mPa · s) of the 0.2% by weight aqueous solution and the intrinsic viscosity (dl / g) measured by the above method is defined as the string length (m) of the 0.4% by weight aqueous solution.
The quotient divided by m) is 50 to 200, more preferably 55 to 80. Rotation speed 3 using a B-type viscometer
Viscosity of 0.2 wt% aqueous solution measured at 0 rpm (mPa ·
s) and the intrinsic viscosity (dl / g) divided by the spinning length (mm) of the 0.4% by weight aqueous solution are less than 50 even if the quotient is less than 50.
Even if it exceeds, the filterability may be poor, the dewatering ability may be insufficient, and the water content of the cake may not be sufficiently reduced.
In the method of the present invention, a 0.2% by weight aqueous solution of a cationic organic polymer flocculant can be prepared as follows. That is, 1.00 g of the purified cationic organic polymer flocculant was precisely weighed, and 499 g of deionized water was added little by little while stirring with a stirrer so as to prevent generation of a granular lump, followed by stirring at 500 rpm for 2 hours. Allow to dissolve for 1 day at room temperature. A 0.4% by weight aqueous solution of the cationic organic polymer flocculant was prepared using 2.00 g of the purified cationic organic polymer flocculant and 498 g of deionized water.
It can be prepared similarly. In the method of the present invention, the viscosity (mPa) of a 0.2% by weight aqueous solution measured at a rotation speed of 30 rpm using a B-type viscometer of a cationic organic polymer flocculant.
・ S) is a value measured at 30 ° C. As the B-type viscometer, a Brookfield single cylinder viscometer such as a B-type viscometer manufactured by Tokyo Keiki Co., Ltd. can be used.
The rotation speed of the rotor is set to 30 rpm, and a combination of the rotation speed and the rotor number is selected such that the scale plate pointer falls within the range of 20 to 100% during viscosity measurement. It is preferable that the rotor rotation time is about 5 minutes until the pointer stabilizes. In the method of the present invention, the spinning length of a 0.4% by weight aqueous solution of the cationic organic polymer flocculant is 30.
It is a value measured at ° C. The spinning length measures the stringiness of the aqueous flocculant solution, and is used as an index relating to the presence or absence of cross-linking or branching between or within the flocculant molecules, and the molecular weight distribution. As a measuring instrument to be used, for example, a string length measuring instrument manufactured by Kyowa Interface Science Co., Ltd. can be exemplified. About 100 ml of a 0.4% by weight aqueous solution of a cationic organic polymer flocculant is placed in a beaker, and the glass spheroid of the thread length measuring device is placed at a height of 11 mm below the liquid level corresponding to the major axis.
After the immersion is continued for 10 to 15 seconds, the film is pulled up at a rising speed of 15.2 mm / sec, and the rising distance from the liquid surface until the yarn breaks is measured. The measurement is repeated 10 times, and the average value is defined as the spinning length.

The dewatering machine used in the method of the present invention is not particularly limited as long as it can be mechanically dewatered. For example, a centrifugal dewatering machine using centrifugal force, and two filter cloths are continuously arranged between many rolls. Belt press dewatering machine which performs the dewatering by gravity, filtering and squeezing and compression by one machine,
A vacuum dewatering machine that sucks and dewaters the sludge adhering to the filter cloth by vacuum, a pressure dehydrator that dewaters by pressing and pressing, and a screw press dewatering that rotates the spiral blade to dewater by pressing Machine and the like. Among these dehydrators, a centrifugal dehydrator can be preferably used, and a high-efficiency centrifugal dehydrator can be particularly preferably used. The high-efficiency centrifugal dewatering machine is a centrifugal dewatering machine with a dewatering mechanism that incorporates the concept of consolidation. As mentioned above, it has been certified by the Japan Sewage Works Agency with a private development technology examination certificate in fiscal 1994. . Examples of the high-efficiency centrifugal dehydrator include, for example, a high-efficiency centrifugal dehydrator (Sentry Ace) manufactured by Tsukishima Kikai Co., Ltd., a high-efficiency centrifugal dehydrator (DM type) manufactured by Tomoe Kogyo, and Kotobuki Giken Kogyo (stock)
High efficiency centrifugal dehydrator (Centrepress). In the method of the present invention, conditions under which a strong shearing force is applied are set to 5,000 rpm using a homogenizer,
It is preferable that the conditions correspond to stirring for 5 seconds or more.
The correspondence between the conditions in which a strong shearing force is applied in the centrifugal dehydrator and the stirring conditions of the homogenizer can be determined as follows. That is, the addition rate (mg / liter) of the flocculant to the sludge is calculated from the sludge supply amount and the flocculant aqueous solution injection amount in the actual apparatus, and the residual flocculant amount in the dehydrated filtrate (separated water) at this time is calculated as Determined by colloid titration. On the other hand, the sludge of the actual apparatus is put into a homogenizer, and after stabilizing at a predetermined rotation speed, a flocculant is added at the same addition rate as the actual apparatus, and the mixture is stirred for a predetermined time and then filtered. Measure. The amount of the residual coagulant in the filtrate after the homogenizer treatment is the same as the amount of the residual coagulant in the dewatered filtrate in the actual apparatus, and the rotation speed of the homogenizer corresponding to the condition where a strong shear force is applied in the centrifugal dehydrator and Stirring time. As a homogenizer to be used, for example, EXC manufactured by NIHONSEIKI KAISHA is used.
EL AUTO HOMOGENIZER ED-7 type,
HIGH-FLEX HOMOGENI manufactured by SMT Corporation
ZER HF93-4, HIGH made by Hirosawa Iron Works Co., Ltd.
POWER HOMOGENIZER PII-C type and the like can be mentioned. According to the organic sludge dewatering method of the present invention, the cake is effectively dewatered by adding a small amount of a chemical, and has a low SS concentration in the separated water, a high SS recovery rate, a high floc strength, and a low water content. Can be obtained.

[0011]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. In addition, the composition of the flocculants A-1 to A-7, the viscosity of the 0.2% by weight aqueous solution, the intrinsic viscosity, the spinning length of the 0.4% by weight aqueous solution, and [(aqueous solution viscosity × intrinsic viscosity)] Table 1 shows the values of the compositions of the coagulants B-1 to B-6, the viscosity of the 0.2% by weight aqueous solution, the intrinsic viscosity, and the value of the 0.4% by weight aqueous solution. Table 2 shows the yarn length and the value of [(aqueous solution viscosity x intrinsic viscosity) / string length].

[0012]

[Table 1]

[0013]

[Table 2]

Test methods in Examples and Comparative Examples are shown below. (1) Estimation of reaction conditions between organic sludge and cationic polymer flocculant Reaction conditions between organic sludge and cationic polymer flocculant in the actual apparatus were estimated by the following method. (1) The sludge supply amount (m ³ / h) and the coagulant aqueous solution injection amount (m ³ / h or liter / min) in the actual apparatus are obtained from a flow meter or a pump stroke, respectively, and the concentration of the coagulant aqueous solution is taken into consideration. The addition rate of flocculant to sludge (mg /
Liters). (2) The amount of the remaining flocculant in the dehydrated filtrate (separated water) at that time is determined by a colloid titration method. 20 ml of the filtrate is collected in a beaker, and 3 to 4 drops of toluidine blue indicator is dropped and titrated with an N / 400 polyvinyl potassium sulfate (PVSK) solution to determine the N / 400 PVSK consumption. (3) 200 ml of the sludge from the actual apparatus was collected in a 500 ml stainless steel container for a homogenizer, and the homogenizer [NIHONSEIKI KAISHA, EXCE
L AUTO HOMOGENIZER ED-7 type], and at the stage where it is stabilized at a predetermined rotation speed, the flocculant of the above (1) is quickly added at the same addition rate as in the actual apparatus, and stirred for 5 seconds. (4) The number of rotations is, for example, 500, 1,000, 2,000
0, 3,000, 5,000, 7,000, 10,000,
For example, 15,000 rpm. (5) After reacting at each rotation speed, a hard vinyl chloride cylinder having an inner diameter of 50 mm is placed on a Buchner funnel covered with a nylon filter cloth, and the flocculated sludge is poured into the cylinder at once, and the filtrate is collected. (6) The amount of residual coagulant in the filtrate is measured by the same method as in (2) above. (7) It is estimated that the number of revolutions at which the same amount of residual flocculant as obtained in (2) above is obtained is a condition in which a strong shearing force is applied to the actual apparatus corresponding to the case where a homogenizer is used. (2) Evaluation of Flock Strength In Examples and Comparative Examples, the flock strength was evaluated by the following method. Place a hard vinyl chloride cylinder with an inner diameter of 50 mm on a Buchner funnel covered with a nylon filter cloth, pour flocculent sludge into the cylinder at a stretch, take up the sludge deposited on the nylon filter cloth, and squeeze it slowly. The strength is determined as follows. Strong: With one hand squeezing, the cake is immediately squeezed and can be squeezed to the end with the maximum grip. Middle: It is narrowed down by one hand squeezing, but at the maximum grip strength,
Cake penetrates between fingers. Weak: When squeezed slowly 4 to 5 times, water comes out and a solid cake is obtained, but when the grip strength is increased, it comes out between the fingers. Impossible: There is no cake left in the hands, almost falling out between the fingers. (3) Application test of conventional centrifugal dehydrator Among the performance evaluation tests, the desktop evaluation test applied to the conventional centrifugal dehydrator was performed by the following method. (1) 200 ml of sludge is collected in a 500 ml stainless steel container for a homogenizer. (2) The stainless steel container containing the sludge is placed in a homogenizer [NIHONSEIKIKAISHA, EXCEL
AUTO HOMOGENIZER ED-7 type], and when it becomes stable at a predetermined speed,
A predetermined amount of a 0.2% by weight aqueous solution of a flocculant is quickly added, followed by stirring for 5 seconds. (3) After measuring the particle size of the formed floc, the hard vinyl chloride cylinder having an inner diameter of 50 mm is placed in a Buchner funnel covered with a nylon filter cloth, and the flocculated sludge is poured into the cylinder at a stretch, and after 20 seconds. Measure the gravity filtrate volume of. (4) Furthermore, regarding the sludge deposited on the nylon filter cloth,
The floc strength is measured, and a certain amount thereof is taken on a filter cloth for a belt press and pressed for 1 minute at a pressure of 0.5 kg / cm ² to measure the water content of the dehydrated cake. (4) Application test of high-efficiency centrifugal dehydrator (1) 200 ml of sludge is collected in a 500 ml stainless steel container for a homogenizer. (2) The stainless steel container containing the sludge is placed in a homogenizer [NIHONSEIKIKAISHA, EXCEL
AUTO HOMOGENIZER ED-7 type], and when it becomes stable at a predetermined speed,
A predetermined amount of a 0.2% by weight aqueous solution of a flocculant is quickly added, followed by stirring for 5 seconds. (3) After measuring the particle size of the formed floc, the hard vinyl chloride cylinder having an inner diameter of 50 mm is placed in a Buchner funnel covered with a nylon filter cloth, and the flocculated sludge is poured into the cylinder at a stretch, and after 20 seconds. Measure the gravity filtrate volume of. (4) Measure the floc strength of the sludge deposited on the nylon filter cloth, take the whole amount into a centrifuge tube,
Centrifuge at 3,000 G for 10 minutes.
The cake deposited on the bottom of the centrifuge tube is collected, mixed well, and then the centrifuge tube is filled with about 100 ml and centrifuged under the same conditions. After repeating this operation 5 times,
The dewatered cake on the bottom side of the centrifuge tube is scraped with a cutter and the moisture content is measured.

In Comparative Examples 1-2 and Examples 1-3, the digested sludge in the night soil treatment plant was subjected to a dehydration treatment. Comparative Example 1 At present, coagulant B-2 is added to digested sludge in a night soil treatment plant by using a centrifugal dehydrator by injecting 210 mg / liter into the machine. The digested sludge has a pH of 6.
9, electric conductivity 205 mS / m, SS 1.61% by weight,
VSS / SS 74.5% by weight, fiber content / SS 2.5% by weight
It is. At present, the water content of the dehydrated cake is 82.0.
~ 83.0 wt%, SS concentration of separation water 200 ~ 600mg
/ Liter, SS recovery rate of 96-98% by weight. The amount of residual flocculant in the dehydrated filtrate of the current product B-2 is 1.2 ml N
/ 400 PVSK / 20 ml filtrate, and the equivalent stirring condition determined by desktop evaluation was 5,000 rpm × 5 seconds with homogenizer stirring. 200 ml of digested sludge is collected in a stainless steel container having a capacity of 500 ml, and a homogenizer [EXCEL manufactured by NIHOHSEIKI KAISHA]
AUTO HOMOGENIZER ED-7 type], and when the number of revolutions became stable at 5,000 rpm, a 0.2% by weight aqueous solution of flocculant B-2 was added to a flocculant concentration of 210 mg.
/ Liter and then stirred for 5 seconds. Next, a hard vinyl chloride cylinder having an inner diameter of 50 mm was placed on a Buchner funnel covered with a nylon filter cloth, and the flocculated sludge was poured into the cylinder at a stretch, and the amount of gravity filtrate after 20 seconds was measured to be 112 ml. The floc strength of the sludge deposited on the nylon filter cloth was medium to strong. The filtered sludge was collected on a filter cloth for a belt press and pressed for 1 minute at a pressure of 0.5 kg / cm ² to obtain a dewatered cake. The water content of the obtained dehydrated cake was 82.0% by weight. Comparative Example 2 Comparative Example 1 using flocculant B-1 instead of flocculant B-2
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
After 2 seconds, the gravity filtrate volume was 106 ml, the floc strength of the sludge was medium to strong, and the water content of the dewatered cake was 82.1% by weight. Example 1 Comparative Example 1 using flocculant A-1 instead of flocculant B-2
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
After seconds, the gravity filtrate volume was 134 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 80.5% by weight. Example 2 Comparative Example 1 using flocculant A-2 instead of flocculant B-2
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
After s, the gravity filtrate volume was 145 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 80.0% by weight. Example 3 Comparative Example 1 using flocculant A-3 instead of flocculant B-2
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
The amount of gravity filtrate after 140 seconds was 140 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 79.8% by weight. Further, using the flocculant A-3 instead of the flocculant B-2,
The actual machine was evaluated. The water content of the dehydrated cake is 79.5 to 8
0.3 wt%, SS concentration of separated water was 34 to 52 mg / liter, and SS recovery was 99.8 wt% or more. Comparative Example 1
Table 2 shows the results of Examples 1 to 3.

[0016]

[Table 3]

As can be seen from the results of the desktop evaluation in Table 3, the quotient obtained by dividing the product of the viscosity of the 0.2% by weight aqueous solution and the intrinsic viscosity by the spinning length of the 0.4% by weight aqueous solution is less than 50. Comparing Comparative Examples 1-2 using the cationic organic polymer flocculant with Examples 1-3 using the cationic organic polymer flocculant whose quotient is 50-200, Better than 2
It can be seen that the amount of filtrate after 0 seconds is large, the floc strength is high, the water content of the cake is low, and the cake is effectively dehydrated. Also, comparing the results of the actual operation of Comparative Example 1 and Example 3, the water content of the cake and the SS concentration of the separated water are lower in Example 3, and the SS recovery rate is higher. It can be seen that a good dehydration effect corresponding to the evaluation was obtained.

In Comparative Examples 3 to 6 and Examples 4 to 7, dewatering was performed on the mixed sludge in the sewage treatment plant. Comparative Example 3 At present, coagulant B-3 is added to mixed sludge in a sewage treatment plant using a centrifugal dehydrator by injecting into a 280 mg / liter machine. The mixed sludge has a pH of 5.
4, electric conductivity 355 mS / m, SS 2.70% by weight,
VSS / SS 75.7% by weight, fiber content / SS 10.8% by weight. At present, the water content of the dewatered cake is 78.
0 to 80.0% by weight, SS concentration of separated water 300 to 1,50
0 mg / l, SS recovery 96-98% by weight.
The amount of residual flocculant in the dehydrated filtrate of the current product B-3 is 0.8.
The stirring conditions were 5 ml N / 400 PVSK / 20 ml filtrate, and the equivalent stirring conditions determined by desktop evaluation were 10,000 rpm × 5 seconds with homogenizer stirring. 200ml of mixed sludge
Was collected in a stainless steel container having a capacity of 500 ml, and a homogenizer [manufactured by NIHOHSEIKI KAISHA, EX
CEL AUTO HOMOGENIZER ED-7
And a 0.2% by weight aqueous solution of flocculant B-3 is added when the rotational speed becomes stable at 10,000 rpm so that the flocculant concentration becomes 280 mg / l.
Stirred for seconds. Next, a hard vinyl chloride cylinder having an inner diameter of 50 mm was placed on a Buchner funnel covered with a nylon filter cloth, and the flocculated sludge was poured into the cylinder at a stretch, and the amount of gravity filtrate after 20 seconds was measured to be 88 ml. The floc strength of the sludge deposited on the nylon filter cloth was medium. The sludge after filtration is taken on a filter cloth for a belt press, and 0.5 kg / cm ²
At a pressure of 1 minute to obtain a dehydrated cake. The water content of the obtained dehydrated cake was 79.7% by weight. Comparative Example 4 Comparative Example 3 using flocculant B-4 instead of flocculant B-3
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
The gravity filtrate volume after 82 seconds is 82ml, and the floc strength of sludge is weak
The water content of the dehydrated cake was 79.9% by weight. Comparative Example 5 Comparative Example 3 was performed using flocculant B-5 instead of flocculant B-3.
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
The gravity filtrate volume after 79 seconds is 79 ml, and the floc strength of sludge is weak
The water content of the dehydrated cake was 80.0% by weight. Comparative Example 6 Comparative Example 3 was performed using the flocculant B-6 instead of the flocculant B-3.
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
After 76 seconds, the gravity filtrate volume is 76 ml, and the floc strength of the sludge is low.
The water content of the dehydrated cake was 80.1% by weight. Example 4 Comparative Example 3 using flocculant A-4 instead of flocculant B-3
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
After 2 seconds, the gravity filtrate volume was 112 ml, the floc strength of the sludge was medium to strong, and the water content of the dewatered cake was 77.6% by weight. Example 5 Comparative Example 3 using flocculant A-5 instead of flocculant B-3
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
The amount of gravity filtrate after 115 seconds was 115 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 76.5% by weight. Example 6 Comparative Example 3 using flocculant A-6 instead of flocculant B-3
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
The gravity filtrate volume after 128 seconds was 128 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 76.4% by weight. Example 7 Comparative Example 3 using flocculant A-7 instead of flocculant B-3
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
The amount of gravity filtrate after 130 seconds was 130 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 76.4% by weight. Further, using a flocculant A-7 instead of the flocculant B-3,
The actual machine was evaluated. The water content of the dehydrated cake is 75.8-7
7.0% by weight, SS concentration of separated water was 114 to 342 mg / L, and SS recovery was 99.9% by weight or more. Table 4 shows the results of Comparative Examples 3 to 6 and Examples 4 to 7.

[0019]

[Table 4]

As can be seen from the results of the desktop evaluation in Table 4, the quotient obtained by dividing the product of the viscosity of the 0.2% by weight aqueous solution and the intrinsic viscosity by the spinning length of the 0.4% by weight aqueous solution is less than 50. Comparison of Comparative Examples 3 to 6 using a cationic organic polymer flocculant with Examples 4 to 7 using a cationic organic polymer flocculant whose quotient is 50 to 200 shows that Examples 4 to 7 Better than 2
It can be seen that the filtrate amount after 0 seconds is large, the floc strength is strong, the water content of the cake is low, and the cake is effectively dehydrated.
Also, comparing the results of the actual operation of Comparative Example 3 and Example 7, the water content of the cake and the SS concentration of the separated water are lower in Example 7, and the SS recovery rate is higher. It can be seen that a good dehydration effect corresponding to the evaluation was obtained.

In Comparative Examples 7 to 12 and Examples 8 to 14, dewatering treatment was performed on the mixed sludge in the sewage treatment plant. Comparative Example 7 At present, coagulant B-3 is added to a mixed sludge in a sewage treatment plant by using a centrifugal dehydrator by injecting 230 mg / liter into the machine. The mixed sludge has a pH of 4.
8, electric conductivity 436 mS / m, SS 4.18% by weight,
VSS / SS 77.2% by weight, fiber content / SS 7.4% by weight
It is. At present, the water content of the dewatered cake is 76.0.
~ 77.0% by weight, SS concentration of separated water 200 ~ 500mg
/ Liter, SS recovery rate of 99.9% by weight or more. The amount of residual flocculant in the dehydrated filtrate of the current product B-3 is 0.7 ml.
The N / 400 PVSK / 20 ml filtrate was used, and the equivalent stirring conditions determined by desktop evaluation were 10,000 rpm × 5 seconds with homogenizer stirring. 200 ml of mixed sludge was collected in a stainless steel container having a capacity of 500 ml, and a homogenizer [manufactured by NIHOHSEIKI KAISHA, EXCE
L AUTOMOGENIZER ED-7 type], and when the rotation speed became stable at 10,000 rpm, a 0.2% by weight aqueous solution of the flocculant B-3 was added to the flocculant at a concentration of 2%.
After adding to 30 mg / liter, the mixture was stirred for 5 seconds. Next, a hard vinyl chloride cylinder having an inner diameter of 50 mm was placed on a Buchner funnel covered with a nylon filter cloth, and the flocculated sludge was poured into the cylinder at a stretch, and the amount of gravity filtrate after 20 seconds was measured to be 19 ml. The floc strength of the sludge deposited on the nylon filter cloth was low to medium. The filtered sludge was collected on a filter cloth for a belt press and pressed for 1 minute at a pressure of 0.5 kg / cm ² to obtain a dewatered cake. The water content of the obtained dehydrated cake was 76.3% by weight. Comparative Example 8 Comparative Example 7 was conducted using the flocculant B-1 instead of the flocculant B-3.
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
Seconds, the gravity filtrate volume is 22ml, the sludge floc strength is medium,
The water content of the dehydrated cake was 76.8% by weight. Comparative Example 9 Comparative Example 7 was conducted using the flocculant B-2 instead of the flocculant B-3.
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
After 21 seconds, the gravity filtrate volume is 21 ml, and the floc strength of the sludge is medium.
The water content of the dehydrated cake was 76.5% by weight. Comparative Example 10 Comparative Example 7 using flocculant B-4 instead of flocculant B-3
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
After 18 seconds, the gravity filtrate volume is 18 ml, the floc strength of the sludge is weak,
The water content of the dehydrated cake was 76.0% by weight. Comparative Example 11 Comparative Example 7 was carried out using flocculant B-5 instead of flocculant B-3.
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
After 18 seconds, the gravity filtrate volume is 18 ml, the floc strength of the sludge is weak,
The water content of the dehydrated cake was 76.1% by weight. Comparative Example 12 Comparative Example 7 was conducted using a flocculant B-6 instead of the flocculant B-3.
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
The gravity filtrate volume after 17 seconds is 17 ml, the floc strength of sludge is weak,
The water content of the dehydrated cake was 76.0% by weight. Example 8 Comparative Example 7 using flocculant A-1 instead of flocculant B-3
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
The gravity filtrate volume after 41 seconds was 41 ml, the floc strength of the sludge was slightly strong, and the water content of the dewatered cake was 75.4% by weight. Example 9 Comparative Example 7 using flocculant A-2 instead of flocculant B-3
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
After 2 seconds, the gravity filtrate volume was 42 ml, the floc strength of the sludge was slightly strong, and the water content of the dewatered cake was 75.1% by weight. Example 10 Comparative Example 7 using flocculant A-3 instead of flocculant B-3
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
The gravity filtrate volume after 42 seconds is 42 ml, the floc strength of the sludge is strong,
The water content of the dehydrated cake was 74.1% by weight. Example 11 Comparative Example 7 using flocculant A-4 instead of flocculant B-3
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
The gravity filtrate volume after 44 seconds is 44 ml, the floc strength of the sludge is strong,
The water content of the dehydrated cake was 73.7% by weight. Example 12 Comparative Example 7 using flocculant A-5 instead of flocculant B-3
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
The gravity filtrate volume after 41 seconds is 41 ml, the floc strength of the sludge is strong,
The water content of the dehydrated cake was 73.4% by weight. Furthermore, actual machine evaluation was performed using flocculant A-5 instead of flocculant B-3. The water content of the dehydrated cake is 73.2 to 75.
The SS concentration of separated water was 97 to 297 mg / liter, and the SS recovery rate was 99.9% by weight or more. Example 13 Comparative Example 7 using flocculant A-6 instead of flocculant B-3
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
The gravity filtrate volume after 44 seconds is 44 ml, the floc strength of the sludge is strong,
The water content of the dehydrated cake was 73.2% by weight. Example 14 Comparative Example 7 using flocculant A-7 instead of flocculant B-3
A coagulation filtration test and a squeeze test were performed in the same manner as described above. 20
The gravity filtrate volume after 46 seconds is 46 ml, the floc strength of sludge is strong,
The water content of the dehydrated cake was 73.1% by weight. Table 5 shows the results of Comparative Examples 7 to 12 and Examples 8 to 14.

[0022]

[Table 5]

As can be seen from the results of the desktop evaluation in Table 5, the quotient obtained by dividing the product of the viscosity of the 0.2% by weight aqueous solution and the intrinsic viscosity by the spinning length of the 0.4% by weight aqueous solution is less than 50. Comparing Comparative Examples 7 to 12 using the cationic organic polymer flocculant with Examples 8 to 14 using the cationic organic polymer flocculant whose quotient is 50 to 200, the results of Examples 8 to 14 One can see that the amount of filtrate after 20 seconds is large, the floc strength is high, the water content of the cake is low, and the cake is effectively dehydrated. Also, comparing the results of the actual operation of Comparative Example 7 and Example 12, the water content of the cake and the SS concentration of the separated water were lower and the SS recovery rate was higher in Example 12, and even in the actual operation, It can be seen that a good dehydration effect corresponding to the evaluation was obtained.

In Comparative Examples 13 to 14 and Examples 15 to 17, a desktop evaluation test applied to a conventional centrifugal dehydrator was performed on digested sludge in a human waste treatment plant. Comparative Example 13 The properties of digested sludge were pH 6.9, electric conductivity 205 mS /
m, SS 1.61% by weight, VSS / SS 74.5% by weight,
Fiber content / SS 2.5% by weight. 200 ml of digested sludge was collected in a stainless steel container having a capacity of 500 ml, and a homogenizer [EXC manufactured by NIHOHSEIKI KAISHA, EXC
EL AUTO HOMOGENIZER ED-7 type]
And when the rotation speed becomes stable at 5,000 rpm, a 0.2% by weight aqueous solution of coagulant B-1 is added to the coagulant at a concentration of 2%.
After adding to 10 mg / liter, the mixture was stirred for 5 seconds. Next, a hard vinyl chloride cylinder having an inner diameter of 50 mm was placed on a Buchner funnel covered with a nylon filter cloth, and the flocculated sludge was poured into the cylinder at a stretch, and the amount of gravity filtrate after 20 seconds was measured to be 86 ml. The floc strength of the sludge deposited on the nylon filter cloth was low. The filtered sludge was collected on a filter cloth for a belt press and pressed for 1 minute at a pressure of 0.5 kg / cm ² to obtain a dewatered cake. The water content of the obtained dehydrated cake was 82.7% by weight. Comparative Example 14 Comparative Example 1 using flocculant B-2 instead of flocculant B-1
A coagulation filtration test and a compression test were performed in the same manner as in Example 3. 2
After 0 seconds, the gravity filtrate volume was 96 ml, the floc strength of the sludge was low to medium, and the water content of the dehydrated cake was 82.2% by weight. Example 15 Comparative Example 1 using flocculant A-1 instead of flocculant B-1
A coagulation filtration test and a compression test were performed in the same manner as in Example 3. 2
After 0 seconds, the gravity filtrate volume was 120 ml, the floc strength of the sludge was medium to strong, and the water content of the dewatered cake was 81.5% by weight. Example 16 Comparative Example 1 using flocculant A-2 instead of flocculant B-1
A coagulation filtration test and a compression test were performed in the same manner as in Example 3. 2
After 0 second, the gravity filtrate volume was 125 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 81.2% by weight. Example 17 Comparative Example 1 using flocculant A-3 instead of flocculant B-1
A coagulation filtration test and a compression test were performed in the same manner as in Example 3. 2
After 0 seconds, the gravity filtrate volume was 110 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 81.0% by weight. Table 6 shows the results of Comparative Examples 13 to 14 and Examples 15 to 17.

[0025]

[Table 6]

As can be seen from the results shown in Table 6, the cationic organic compound whose quotient obtained by dividing the product of the viscosity of the 0.2% by weight aqueous solution and the intrinsic viscosity by the spinning length of the 0.4% by weight aqueous solution is less than 50. Comparative Examples 13 and 14 using a polymer flocculant, and the quotient is 50 to
Comparing Examples 15 to 17 using the cationic organic polymer flocculant of 200, Examples 15 to 17 are
It can be seen that the amount of filtrate after 20 seconds is large, the flock strength is strong, the water content of the cake is low, and the cake is effectively dehydrated.

In Comparative Examples 15 to 16 and Examples 18 to 20, the digested sludge from the urine treatment plant used in Comparative Examples 13 to 14 and Examples 15 to 17 was evaluated on a desk applied to a high-efficiency centrifugal dehydrator. The test was performed. Comparative Example 15 200 ml of digested sludge was collected in a stainless steel container having a capacity of 500 ml, and the homogenizer [NIHOHSEIKI KA] was used.
EXCEL AUTO HOMOGENIZ made by ISHA
ER ED-7 type] at 5,000 rpm
When it became stable, a 0.2% by weight aqueous solution of flocculant B-1 was added so that the flocculant concentration became 210 mg / l, and the mixture was stirred for 5 seconds. Next, a hard vinyl chloride cylinder having an inner diameter of 50 mm was placed on a Buchner funnel covered with a nylon filter cloth, and the coagulated sludge was poured into the cylinder at once, and
When the gravity filtrate amount after 0 seconds was measured, it was 86 ml. The floc strength of the sludge deposited on the nylon filter cloth is
It was weak. Collect the sludge after filtration in a centrifuge tube, and
Centrifugation was performed for 10 minutes at the centrifugal force of G, the cake deposited on the bottom of the centrifuge tube was collected, mixed well, and then approximately 100 ml was further filled into the centrifuge tube and centrifuged under the same conditions. After repeating this operation five times, the dewatered cake on the bottom of the centrifuge tube was scraped off with a cutter, and the water content was measured. As a result, it was 81.0% by weight. Comparative Example 16 Comparative Example 1 using flocculant B-2 instead of flocculant B-1
A coagulation filtration test and a centrifugation test were performed in the same manner as in Example 5. After 20 seconds, the gravity filtrate volume was 96 ml, the floc strength of the sludge was low to medium, and the water content of the dewatered cake was 80.9% by weight. Example 18 Comparative Example 1 using flocculant A-1 instead of flocculant B-1
A coagulation filtration test and a centrifugation test were performed in the same manner as in Example 5. After 20 seconds, the gravity filtrate volume was 120 ml, the floc strength of the sludge was medium to strong, and the water content of the dewatered cake was 79.6% by weight. Example 19 Comparative Example 1 using flocculant A-2 instead of flocculant B-1
A coagulation filtration test and a centrifugation test were performed in the same manner as in Example 5. After 20 seconds, the gravity filtrate volume was 125 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 78.3% by weight. Example 20 Comparative Example 1 using flocculant A-3 instead of flocculant B-1
A coagulation filtration test and a centrifugation test were performed in the same manner as in Example 5. After 20 seconds, the gravity filtrate volume was 110 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 78.1% by weight. The results of Comparative Examples 15 to 16 and Examples 18 to 20,
It is shown in Table 7.

[0028]

[Table 7]

As can be seen from the results shown in Table 7, the cationic organic compound whose quotient obtained by dividing the product of the viscosity of the 0.2% by weight aqueous solution and the intrinsic viscosity by the spinning length of the 0.4% by weight aqueous solution is less than 50. Comparative Examples 15 to 16 using a polymer flocculant, and the quotient is 50 to
Comparing Examples 18 to 20 using the cationic organic polymer flocculant that is 200, Examples 18 to 20 have a lower cake moisture content, even under the conditions applied to a high-efficiency centrifugal dehydrator. It turns out that it is dehydrated effectively.

In Comparative Examples 17 to 18 and Examples 21 to 23, an on-board evaluation test applied to a conventional centrifugal dehydrator was performed on mixed sludge in a sewage treatment plant. Comparative Example 17 The mixed sludge had a pH of 4.8 and an electrical conductivity of 436 mS /
m, SS 4.18% by weight, VSS / SS 77.2% by weight,
Fiber content / SS 7.4% by weight. 200 ml of digested sludge was collected in a stainless steel container having a capacity of 500 ml, and a homogenizer [EXC manufactured by NIHOHSEIKI KAISHA, EXC
EL AUTO HOMOGENIZER ED-7 type]
When the rotational speed becomes stable at 5,000 rpm, a 0.2% by weight aqueous solution of coagulant B-4 is added to the coagulant at a concentration of 2%.
After adding to 30 mg / liter, the mixture was stirred for 5 seconds. Next, a hard vinyl chloride cylinder having an inner diameter of 50 mm was placed on a Buchner funnel covered with a nylon filter cloth, and the flocculated sludge was poured into the cylinder at a stretch, and the amount of gravity filtrate after 20 seconds was measured to be 19 ml. The floc strength of the sludge deposited on the nylon filter cloth was low to medium. The filtered sludge was collected on a filter cloth for a belt press and pressed for 1 minute at a pressure of 0.5 kg / cm ² to obtain a dewatered cake. The water content of the obtained dehydrated cake was 76.3% by weight. Comparative Example 18 Comparative Example 1 using flocculant B-5 instead of flocculant B-4
A coagulation filtration test and a compression test were performed in the same manner as in Example 7. 2
After 0 seconds, the gravity filtrate volume was 18 ml, the floc strength of the sludge was weak, and the water content of the dewatered cake was 76.0% by weight. Example 21 Comparative Example 1 using flocculant A-4 instead of flocculant B-4
A coagulation filtration test and a compression test were performed in the same manner as in Example 7. 2
After 0 second, the gravity filtrate volume was 41 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 73.4% by weight. Example 22 Comparative Example 1 using flocculant A-5 instead of flocculant B-4
A coagulation filtration test and a compression test were performed in the same manner as in Example 7. 2
After 0 seconds, the gravity filtrate volume was 44 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 73.2% by weight. Example 23 Comparative Example 1 using flocculant A-6 instead of flocculant B-4
A coagulation filtration test and a compression test were performed in the same manner as in Example 7. 2
After 0 seconds, the gravity filtrate volume was 46 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 73.1% by weight. Table 8 shows the results of Comparative Examples 17 to 18 and Examples 21 to 23.

[0031]

[Table 8]

As can be seen from the results in Table 8, the cationic organic compound having a quotient of less than 50 obtained by dividing the product of the viscosity of the 0.2% by weight aqueous solution and the intrinsic viscosity by the spinning length of the 0.4% by weight aqueous solution is less than 50. Comparative Examples 17 to 18 using a polymer flocculant and the quotient of 50 to
Comparing Examples 21 to 23 using the cationic organic polymer flocculant of 200, Examples 21 to 23 are
It can be seen that the amount of filtrate after 20 seconds is large, the flock strength is strong, the water content of the cake is low, and the cake is effectively dehydrated.

In Comparative Examples 19 to 20 and Examples 24 to 26, the mixed sludge of the sewage treatment plant used in Comparative Examples 17 to 18 and Examples 21 to 23 was evaluated on a desk applied to a high-efficiency centrifugal dewatering machine. The test was performed. Comparative Example 19 200 ml of mixed sludge was collected in a stainless steel container having a capacity of 500 ml, and the homogenizer [NIHOHSEIKI KA] was used.
EXCEL AUTO HOMOGENIZ made by ISHA
ER ED-7 type] at 5,000 rpm
When the mixture became stable in step (2), a 0.2% by weight aqueous solution of flocculant B-4 was added so that the flocculant concentration became 230 mg / l, and the mixture was stirred for 5 seconds. Next, a hard vinyl chloride cylinder having an inner diameter of 50 mm was placed on a Buchner funnel covered with a nylon filter cloth, and the coagulated sludge was poured into the cylinder at once, and
The gravity filtrate amount after 0 seconds was measured and found to be 19 ml. The floc strength of the sludge deposited on the nylon filter cloth is
Low to medium. Collect the sludge after filtration in a centrifuge tube,
Centrifugation was performed for 10 minutes at a centrifugal force of 00G, and the cake deposited on the bottom of the centrifuge tube was collected and mixed well, and then approximately 100 ml was filled in the centrifuge tube and centrifuged under the same conditions. After repeating this operation five times, the dewatered cake on the bottom of the centrifuge tube was scraped off with a cutter, and the water content was measured. As a result, it was 74.4% by weight. Comparative Example 20 Comparative Example 1 was performed using flocculant B-5 instead of flocculant B-4.
A coagulation filtration test and a centrifugation test were performed in the same manner as in Example 9. After 20 seconds, the gravity filtrate volume was 18 ml, the floc strength of the sludge was weak, and the water content of the dewatered cake was 73.8% by weight. Example 24 Comparative Example 1 using flocculant A-4 instead of flocculant B-4
A coagulation filtration test and a centrifugation test were performed in the same manner as in Example 9. After 20 seconds, the gravity filtrate volume was 41 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 70.6% by weight. Example 25 Comparative Example 1 using flocculant A-5 instead of flocculant B-4
A coagulation filtration test and a centrifugation test were performed in the same manner as in Example 9. After 20 seconds, the gravity filtrate volume was 44 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 70.2% by weight. Example 26 Comparative Example 1 using flocculant A-6 instead of flocculant B-4
A coagulation filtration test and a centrifugation test were performed in the same manner as in Example 9. After 20 seconds, the gravity filtrate volume was 46 ml, the floc strength of the sludge was strong, and the water content of the dewatered cake was 70.3% by weight. The results of Comparative Examples 19 to 20 and Examples 24 to 26,
It is shown in Table 9.

[0034]

[Table 9]

As can be seen from the results in Table 9, a cationic organic compound in which the quotient obtained by dividing the product of the viscosity of the 0.2% by weight aqueous solution and the intrinsic viscosity by the spinning length of the 0.4% by weight aqueous solution is less than 50. Comparative Examples 19 to 20 using a polymer flocculant and the quotient of 50 to
Comparing Examples 24 to 26 using the cationic organic polymer flocculant that is 200, Examples 24 to 26 have lower cake moisture content, even under the conditions applied to a high-efficiency centrifugal dehydrator. It turns out that it is dehydrated effectively.

In Comparative Example 21 and Example 27, the mixed sludge of the excess sludge in the night soil treatment plant and the septic tank sludge was used.
An actual machine evaluation test was performed using a high-efficiency centrifugal dehydrator. Comparative Example 21 The properties of the mixed sludge were pH 7.0, electric conductivity 258 mS /
m, SS 1.58 wt%, VSS / SS 75.2 wt%,
Fiber content / SS 5.1% by weight. The coagulant B-4 was added to the mixed sludge at 160 mg / liter, that is, 1.0% by weight based on SS, and the difference between the rotation speed of the ball and the screw, that is, the differential speed was 4 rpm, and the high efficiency type was used. A centrifugal dehydration treatment was performed. The water content of the obtained cake is 7
8.3% by weight, SS concentration in separated water is 1,270mg
/ Liter. Example 27 Instead of the coagulant B-4, an actual machine evaluation test using the same high-efficiency centrifugal dehydrator as in Comparative Example 21 was performed using the coagulant A-5. The water content of the obtained cake was 74.8% by weight, and the SS concentration in the separated water was 23 mg / L.
Table 10 shows the results of Comparative Example 21 and Example 27.

[0037]

[Table 10]

The cationic organic polymer flocculant B-4 used in Comparative Example 21 and the cationic organic polymer flocculant A-5 used in Example 27 were both methyl chloride 4 of dimethylaminoethyl acrylate. A 70/30 molar ratio of graded product and acrylamide, having the same composition, but as shown in Table 10, 0.2% by weight
Comparative Example 21 using flocculant B-4 having a quotient of 44 obtained by dividing the product of the viscosity of the aqueous solution and the intrinsic viscosity by the spinning length of the 0.4% by weight aqueous solution, and flocculant A- having a quotient of 61 Comparing Example 27 using No. 5, it can be seen that Example 27 has a lower cake moisture content, a lower SS concentration in the separated water, a higher SS recovery, and an effective dehydration treatment.

[0039]

According to the method for dewatering organic sludge of the present invention, dewatering is effectively performed by adding a small amount of a chemical, so that the SS concentration in the separated water is low, the SS recovery rate is high, and the floc strength is high. A cake having a low moisture content can be obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D015 BA06 BA08 BA09 BA10 BB05 CA11 DB04 DB07 DC02 DC07 EA04 EA39 4D059 AA01 AA03 AA23 BE19 BE38 BE57 DB11 DB24 DB25

Claims (3)

[Claims] 1. An organic sludge which is obtained by adding a cationic organic polymer flocculant to an organic sludge and reacting the organic sludge with the cationic organic polymer flocculant under a condition where a strong shearing force is applied. In the dehydration method, the intrinsic viscosity is 3 dl / g or more, and the viscosity (mPa · s) and the intrinsic viscosity (dl / g) of a 0.2% by weight aqueous solution measured at a rotation speed of 30 rpm using a B-type rotational viscometer. Is multiplied by the spinning length (m
A method for dehydrating organic sludge, comprising adding a cationic organic polymer flocculant having a quotient of 50 to 200 divided by m) and mechanically dehydrating using a dehydrator. 2. The method for dewatering organic sludge according to claim 1, wherein the condition under which a strong shearing force is applied is a condition corresponding to stirring at 5,000 rpm for 5 seconds or more using a homogenizer. 3. The method for dewatering organic sludge according to claim 1, wherein the organic sludge is organic sludge generated from sewage / human wastewater treatment or industrial wastewater, and the dewatering machine is a centrifugal dewatering machine.