JPH09216000A - Sludge dewatering method and sludge dewatering device used therefor - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a sludge dewatering method for obtaining a dehydrated cake having a low and stable water content and an apparatus used therefor. SOLUTION: A coagulant and a crushed product of waste paper are mixed with sludge to form a coagulated sludge 3a.
Filter cloths 1a, 1b circulating between ₁ and the pressure dehydration unit B ₂
When the water is supplied to a belt press type dehydrator B equipped with a water separator for dehydration, the water content of the obtained dehydrated cake 3b is measured by a water content meter C, and the measured value and the target water content are calculated by the arithmetic and control unit D. Is compared and calculated, and the admixture amount of crushed waste paper and / or the running speed of the filter cloth is controlled so that the water content of the dehydrated cake shows a value within a predetermined range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sludge dewatering method performed by a belt press type dewatering machine and a sludge dewatering apparatus used therefor. More specifically, the sludge dewatering apparatus is capable of treating sludge even if its concentration or properties vary. The present invention relates to a sludge dewatering method and a sludge dewatering device used therefor capable of obtaining a dehydrated cake having a low water content and a stable value regardless of fluctuations.

[0002]

2. Description of the Related Art Generally, in a large-scale sludge treatment facility,
The optimum amount of coagulant is mixed with the raw sludge to make coagulated sludge,
It is practiced to supply this coagulated sludge to a dehydrator, press and dehydrate it, and incinerate the resulting dehydrated cake. As a dehydrator used at this time, a belt press type dehydrator is widely used.

This belt press type dewatering machine is provided with a gravity dewatering section B ₁ and a pressure dewatering section B ₂ which will be described later, as shown in the schematic construction of FIG. 4, and drives a filter cloth driving motor M ₄ . Due to the force, the pair of filter cloths 1a and 1b are respectively moved by the arrows q
By traveling in the ₁ and q ₂ directions at a predetermined speed, the whole is traveling in circulation in the caging 2 between the gravity dehydration section B ₁ and the pressurized dehydration section B ₂ .

When performing the dehydration treatment, first, the coagulated sludge 3a is continuously supplied from the upper opening of the caging 2 to the upper surface of the one filter cloth 1a. The fed coagulated sludge 3a is fed to the gravity dehydration section B ₁ by the filter cloth 1a with an arrow q.
Gravity dehydration (filtration) progresses in the process of being conveyed in two directions, and a filtered material of a certain thickness remains on the filter cloth 1a.

Then, the above-mentioned filtered material is separated from another filter cloth 1b.
And is passed through a pressure dehydration unit B ₂ composed of a plurality of rollers 4 arranged in the running direction of the filter cloth. In this process, the filtered material sandwiched between the filter cloth 1a and the filter cloth 1b is squeezed by the group of rollers 4 and further dehydration proceeds. The filter cloth 1a and the filter cloth 1b are separated by the roller 4a at the rearmost portion, and the above-described operation is repeated for each. Then, the filtered matter that has been compressed and dehydrated in the pressure dehydration unit B ₂ is scraped off from each filter cloth as the dehydrated cake 3b and transferred to the next incineration process step.

The dehydrated cake 3b thus obtained
Is a cake having a certain water content which is regulated by the operating conditions of the belt press dehydrator B and the degree of agglomeration of the coagulated sludge supplied. When the dehydrated cake is incinerated, after the dehydrated cake is put into an incinerator, auxiliary fuel is added thereto by using heavy oil, coal powder or the like. At this time, the water component is first evaporated and removed from the dehydrated cake by the added combustion heat, and thereafter, the sludge of the dehydrated cake is ignited and burned.

In the above incineration process, when the water content of the dehydrated cake is high, a large amount of auxiliary fuel is required, which is not preferable from the viewpoint of energy saving. The lower the water content of the dehydrated cake, the lower the water content. Seems to be suitable. However, if the water content of the dehydrated cake becomes too low, the amount of heat generated during incineration becomes excessive and the temperature inside the furnace rises excessively, making it impossible to control the temperature. In order to prevent such a situation, it is sufficient to reduce the incineration amount of the dehydrated cake, but such a treatment causes a decrease in treatment efficiency and complicates the operating conditions of the incinerator, which is preferable. It cannot be said that.

From the above, it is considered that the dehydrated cake to be incinerated preferably has a water content in the vicinity of the self-burning range where the incinerator can be operated even with a small amount of auxiliary combustion. There is. Usually, the water content in that case is 73
It is about 75%. By the way, when the sewage sludge is dehydrated, the water content of the dehydrated cake obtained by the normal operation of the belt press dehydrator is 70% to 80% or more because the concentration and the properties of the sludge are drastically changed. It varies in the range. Therefore, when incinerating this dehydrated cake, there is a problem that proper management of the auxiliary fuel amount and selection of appropriate operating conditions of the incinerator become very complicated.

Therefore, in the case of the dehydrated cake to be incinerated, it is preferable that the water content thereof is a value in the vicinity of the self-combustion region in which the incinerator can be operated with a small amount of auxiliary combustion, but this is not sufficient. Therefore, it is necessary to supply the water to the incineration process step with a constant water content after the dehydration process. By the way, in order to reduce the water content of the dehydrated cake, it is effective to add fibrous substances such as pulp and wood flour to the raw sludge and mix them in the process of converting the raw sludge into coagulated sludge. It has been known. However, in the case of the above method, although it is possible to certainly reduce the water content of the dehydrated cake, it is difficult to suppress the variation of the water content, and to solve the above-mentioned problems during incineration treatment is not.

[0010]

DISCLOSURE OF THE INVENTION The present invention solves the above problems in a dehydrated cake obtained by mixing pulp or the like with raw sludge to obtain a flocculated sludge, and concentrating the sludge to be treated. The moisture content of the dehydrated cake can be set to a low value in the vicinity of the self-combustion range, and even if the properties change, the water content can be controlled to a constant value, and therefore the operating conditions of the incinerator It is an object of the present invention to provide a sludge dewatering method and a sludge dewatering device used therefor, which can facilitate the management of wastewater.

[0011]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventors of the present invention have conducted diligent research. As a result, the raw sludge is mixed with a pulverized waste paper together with a flocculant to form a flocculated sludge, In the case of dewatering with a press dewatering machine, the dewatering speed in the belt press dewatering machine is regulated by the admixture amount of the waste paper pulverization, and the fact that the dewatering speed is proportional to the logarithm of the squeezing time during operation of the belt press dewatering machine The present invention has led to the development of a sludge dewatering method of the present invention and a sludge dewatering apparatus used therefor.

That is, in the sludge dewatering method of the present invention, a flocculant and a crushed product of waste paper are mixed with sludge to form a flocculated sludge, and the flocculated sludge is circulated between a gravity dehydration unit and a pressure dehydration unit. When supplied to a belt press type dehydrator equipped with a filter cloth for dehydration, the water content of the obtained dehydrated cake is measured, and based on the measured value, the water content of the dehydrated cake is within a predetermined range. It is characterized by controlling the admixture amount of the pulverized waste paper and / or the traveling speed of the filter cloth so as to indicate the value of.

In the above-mentioned sludge dewatering method, in the present invention, the upper limit value and the lower limit value of the traveling speed of the filter cloth are set by the thickness of the filtered material deposited on the filter cloth in the gravity dehydration section. A method for dehydrating sludge is provided. Further, the sludge dewatering device of the present invention is a means for mixing a coagulant and a crushed product of waste paper into sludge to form coagulated sludge; a belt press type dewatering machine for dewatering the coagulated sludge; and a discharge from the belt press type dewatering machine. A water content meter for measuring the water content of the dehydrated cake; and a signal for inputting the output signal of the water content meter, calculating the output signal, and controlling the filter cloth running speed of the belt press type dehydrator and And a calculation control device for outputting a signal for controlling the admixture amount of the pulverized waste paper.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A series of processes leading to the development of the present invention will be described below. 1. Experiments that are the basis of the present invention (1) Relationship between admixture amount of waste paper pulverized product, dehydration rate, and squeezing time First, waste newspaper is dry pulverized and then classified using a sieve,
A powder having the particle size distribution shown in Table 1 was obtained.

[0015]

[Table 1]

Sewage digestion and cleaning sludge of S treatment plant (TS: 2.1
% By weight, SS: 1.98% by weight, VSS / SS: 56.8
%) 200 ml was collected in a beaker with a capacity of 300 ml, and the used paper powder having a particle size of 2 mm or less and a dehydrating agent of dimethylaminoethyl methacrylate (DAM) homopolymer (trade name: Cliffix CP604, intrinsic viscosity:
After adding the solution of 5.3) in a predetermined amount (against TS: 0.86%), the whole was stirred with a turbine blade having a diameter of 40 mm for 45 seconds to obtain coagulated sludge.

At this time, the mixing amount of the waste paper powder into the sludge is changed to 6.2% by weight, 12.4% by weight, 20% by weight and 40% by weight to form a coagulated sludge, and only the waste paper powder ( Aggregated sludge was also used in the case of 100% by weight of used paper powder) and the case where the used paper powder was not mixed (0% by weight of used paper powder, only the dehydrating polymer). Then, 60
Gravity filtration was carried out with a Buchner funnel laid with a mesh nylon filter cloth, and the filtration product obtained on the filter cloth was superposed on a water-absorbent cloth (commercial name: T-1189, Shikishima Cambes ( Column) (inner diameter 30m)
m, height 17.5 mm) was stuffed with fingers and pre-pressed.

After removing the column, the upper surface and the lower surface are sandwiched between the squeezing filter cloth and the sponge, and the whole is placed on a support stand, and a pressure of 1.0 kg / cm ² is applied from above using an air cylinder. The compression dehydration treatment was performed by changing the compression time. In the above-mentioned experiment, the result of the compression dehydration treatment when the compression time was set to 60 seconds is the standard operating condition of Hyde Press (brand name of belt press dehydrator manufactured by Kurita Water Industries Ltd., filter cloth length: 10 m). (Running speed of filter cloth: 1.0m
/ Min or dehydration time: 10 minutes, filter cloth tension: 7 kg / cm
That is, it is equivalent to the result of dehydration performed at the calculated surface pressure: 1.0 kg / cm ² .

When actually operating the above-mentioned hide press, it is practical that the running speed of the filter cloth is within the range of 0.5 to 2.0 m / min. The water content ratio (R) of each obtained dehydrated cake was determined. The water content ratio (R) described above is R =
It is a value represented by the amount of water / the amount of solid matter, for example, R is 5
If dehydrated to → 4 or 4 → 3, in this process,
This means that only the same amount of water was removed per unit solid amount.

The relationship between the water content (W) and the water content ratio (R), which is usually used, is as follows: W (%) = water content × 100 / (solid content + water content) = R × 100 / (R + 1). The result of the above-mentioned experiment is shown in FIG.

As is clear from FIG. 1, when the mixing amount of the waste paper powder is increased, the pressing time for obtaining the dehydrated cake having the same water content ratio can be shortened. And the dehydration rate is proportional to the logarithm of the pressing time. This indicates that a dehydrated cake having an arbitrary water content can be obtained in a constant state by controlling the amount of waste paper powder mixed and the pressing time.

(2) Analysis of FIG. 1 By the way, the actual calorific value of the solid matter of the sludge used in (1) was measured and found to be 3500 Kcal. The actual calorific value of the waste paper powder was 4,100 Kcal. Therefore,
For example, the true calorific value of the solid content of the dehydrated cake obtained by mixing 30% by weight of waste paper powder is 3500 Kcal × 0.7 + 4100 Kcal × 0.3 = 3680 Kc
Calculated as al.

By the way, the heat capacity of this dehydrated cake is
The following simple formula: True calorific value x ((100-W) / 100) -600 x (W
/ 100) (where W is the water content). According to the above formula, when the water content is 73%, the heat capacity of this dehydrated cake is 545 Kcal / kg cake.

By the way, in general, when the heat content of the dehydrated cake is 500 Kcal / kg or more, the dehydrated cake is said to enter the self-burning region in a fluidized bed type incinerator. Taking the above into consideration, when the mixing amount of waste paper powder changes, the pressing time required to obtain a dehydrated cake with a water content of 73% (water content ratio of 2.7) is obtained from FIG. Be organized as

In Table 2, it is necessary to obtain a dehydrated cake having a water content ratio of 2.7 (water content 73%) by using the above-mentioned Hyde Press (belt press dehydrator manufactured by Kurita Water Industries Ltd.). The estimated values of various dehydration times and the estimated running speed of the filter cloth are also shown. In the experiment of (1), the pressing time was 60 seconds (the running speed of the filter cloth was 1.
Table 2 also shows the water content ratio and water content of the dehydrated cake obtained when the water content is set to 0 m / min).

[0026]

[Table 2]

As is apparent from Table 2, when the waste paper powder was not mixed with the sludge, the squeezing in the laboratory experiment was carried out assuming the running speed of the filter cloth of the Hyde press (belt press dehydrator) to be 1.0 m / min which is the standard. At time (60 seconds), the water content of the obtained dehydrated cake is 80.4%, and the water content does not fall within the self-burning range. The squeezing time in the laboratory experiment to make it a self-burning area is 45
At 0 seconds, this is the running speed of the filter cloth in Hyde Press.
This corresponds to 0.13 m / min.

Further, the following has been clarified. That is, when the mixing amount of the waste paper powder is 12.4% by weight, the estimated value of the running speed of the filter cloth is 0.52 m / min when the moisture content of self-combustion in the Hide Press is 73%.
Further, when the mixing amount of the waste paper powder is set to 20.0% by weight, the estimated running speed of the filter cloth is 1.07 m / min. And
The practical running speed of the filter cloth in this hide press is
As described above, since the range of 0.5 to 2 m / min is suitable, when the Hydepress is operated at the running speed of the filter cloth within this range, the dehydration in the self-burning range where the water content is around 73% You can get a cake.

That is, when operating a Hyde press (belt press dehydrator), the amount of waste paper powder mixed with sludge,
By controlling the running speed of the filter cloth within the practical range described above, the water content of the obtained dehydrated cake can be adjusted to 73% of the self-burning range.
% It can be controlled in the vicinity. (3) Demonstration test based on analysis results At the S treatment plant, TS: 1.99 to 2.17% by weight, S
S: 1.87 to 2.10% by weight, VSS / SS: 56.6 to 5
The following verification tests were conducted on sludge that fluctuates to 7.2%.

That is, the above-mentioned DAM homopolymer was added to the above sludge, and further, the above-mentioned waste paper powder was added in an amount of 0% by weight (without mixing the waste paper powder), 13% by weight, 18% by weight.
The mixture was mixed into three types of coagulated sludge. Each coagulated sludge was supplied to the gravity dehydration section of the belt press dehydrator at a feed rate of 11.5 m ³ / hr and operated at a filtration rate of 76 to 81 kg / m · hr.

At this time, the running speed of the filter cloth was changed and the water content of the obtained dehydrated cake was measured. In addition, the thickness of the filtration product formed in the gravity dehydration section was also measured. The above results are shown in FIG. In the figure, the number in parentheses represents the thickness (mm) of the filtered material in the gravity dehydration section. The following is clear from FIG.

In any case, as the running speed of the filter cloth is increased, the water content of the dehydrated cake increases linearly and the thickness of the filtered material decreases. When the waste paper powder is not mixed, the practical lower limit of the running speed of the filter cloth in the belt press dehydrator is 0.5 m / mi.
When operated at n, the water content of the obtained dehydrated cake is 78%
Then, the thickness of the filtered material becomes 50 mm, which is the operation limit value of the dehydrator, and the water content of the dehydrated cake cannot be further reduced.

When 13% by weight of waste paper powder is mixed, the water content of the dehydrated cake is 73% and the thickness of the filtered product is 48 mm when the running speed of the filter cloth is 0.5 m / min. When 18% by weight of waste paper powder is mixed, the water content of the dehydrated cake is 73% when the running speed of the filter cloth is 0.85 m / min.
Can be At this time, the thickness of the filtered material is 30 mm.
However, the thickness is such that a sufficient margin is left with respect to the operation limit value of the dehydrator.

As is clear from this demonstration test, when the crushed waste paper is mixed with the coagulant into the sludge to form the coagulated sludge, the running speed of the filter cloth in the belt press dehydrator is increased, that is, the dehydration time is short. Even if it exists, a dehydrated cake with a low water content can be obtained. At this time, as is clear from FIG. 2, since the running speed of the filter cloth and the water content of the dehydrated cake have a linear relationship, the measured value of the water content of the obtained dehydrated cake is fed back to the operation system of the belt press dehydrator. Then, by adjusting the running speed of the filter cloth so as to obtain the target water content, a dehydrated cake having a constant water content can be obtained.

As is clear from FIG. 1 showing the experimental result of (1), the relationship between the water content ratio (corresponding to the water content) of the dehydrated cake and the pressing time (corresponding to the dehydration time) is A linear relationship with different slopes is shown corresponding to the admixture amount. The pressing time is proportional to the running speed of the filter cloth in the belt press dehydrator. Therefore,
Dewatering is performed with the running speed of the filter cloth kept constant, the water content of the obtained dehydrated cake is measured, and the measured value is fed back to the mixing device for the pulverized waste paper to obtain the target water content. By adjusting the admixture amount of the pulverized waste paper as described above, a dehydrated cake having a constant water content can be obtained at this time as well.

2. Sludge dewatering device and dewatering method Fig. 3 shows a schematic view of an example of the sludge dewatering device of the present invention.
This apparatus comprises means A for mixing sludge with a flocculant and pulverized waste paper to form sludge, belt press dehydrator B located downstream of this means A, and discharge from this belt press dehydrator B. The moisture content meter C for measuring the moisture content of the dehydrated cake 3b, and the output signal of the moisture content meter C are input and calculated, and a signal for controlling the running speed of the filter cloth in the belt press dehydrator B, and An arithmetic and control unit D for outputting a signal for controlling the admixture amount of pulverized waste paper is provided.

The means A described above is the sludge mixing tank A.
₁ , a sludge supply tank A ₂ arranged on the upstream side, and a crushed waste paper dispersion tank A ₃ also arranged on the upstream side. In this apparatus, first, the sludge 3 to be treated is supplied to the sludge supply tank A ₂ and is stirred by the stirrer 5a driven by the drive motor M ₁ , and then the sludge 3 is supplied to the sludge pump P _{1 at a} predetermined sludge supply amount. Is continuously supplied to the sludge mixing tank A ₁ through the pipe p ₁ .

On the other hand, after a predetermined amount of the crushed waste paper stored in the hopper 6 is weighed in the measuring tank 7, it is put into the crushed waste paper dispersion tank A ₃ , and a predetermined amount of water is further injected therein. After that, it is agitated by an agitator 5b driven by a drive motor M ₂ to prepare a slurry 8 of pulverized waste paper having a predetermined concentration. A predetermined amount of this slurry 8 is continuously conveyed by a slurry injection pump P ₂ through a pipe p ₂ and merges with the sludge 3 at an appropriate position of the pipe p ₁ and then a sludge mixing tank A ₁
Is continuously supplied to.

The sludge 3 and the slurry 8 of crushed waste paper supplied to the sludge mixing tank A ₁ are agitated by an agitator 5c driven by a drive motor M ₃ . At this time, sludge mixing tank A ₁
A predetermined amount of coagulant is added from the coagulant storage tank A ₄ . Thus, the sludge, the crushed waste paper, and the coagulant are mixed, and the coagulated sludge 3a in which a predetermined amount of the crushed waste paper is mixed is prepared.

Examples of the crushed waste paper include dry crushed newspaper waste paper, office waste paper, advertising waste paper, cardboard waste paper, and the like. In particular, newspaper waste paper,
A crushed waste paper for office use is preferable. The particle size thereof is not particularly limited, but a particle size under 10 mesh (Tyler sieve) is suitable, for example. Further, the aggregating agent may be either an inorganic type or an organic type. Examples of suitable inorganic flocculants include ferric chloride, ferric polysulfate, and polyaluminum chloride.

Suitable examples of the organic flocculant include a cationic polymer or an amphoteric polymer. Of these, examples of the cationic polymer include dimethylaminoethyl acrylate (DAA), dimethylaminoethyl methacrylate (DAM), dimethylaminopropyl (meth) acrylate, and cationic monomers such as quaternized products thereof alone. Examples thereof include a polymer or a copolymer of the above-mentioned cationic monomer and an anionic monomer such as acrylic acid (AA), sodium acrylate (NaA), methacrylic acid or sodium methacrylate.

Specific examples of the above-mentioned quaternary compound include methyl chloride quaternary compound and benzyl chloride quaternary compound, and dimethylaminopropyl acrylamide hydrochloride (DMAPAA) is used. You can also As the amphoteric polymer, a copolymer of the above-mentioned cationic monomer and anionic monomer; the above-mentioned cationic monomer and anionic monomer, for example, acrylamide (AAm), methacrylamide, N, N'-dimethyl (meth) acrylamide And a Mannich modified product or a Hoffmann degradation product of the above-mentioned copolymer of an anionic monomer and a nonionic monomer; and the like.

Specifically, examples of the coagulant used include DAA / AAm copolymer, DAM / AAm copolymer, DMAPAA / AAm copolymer, DAA / AA / A.
Am copolymer, DAM / AA / AAm copolymer, DAA
/ DAM / AA / AAm copolymer, DMAPAA / AA
Suitable examples thereof include a Mannich modified product of a / AAm copolymer or a NaA / AAm copolymer.

These coagulants are used for the TS of sludge to be treated.
About 0.1 to 1% by weight of the total solid content may be mixed. The coagulated sludge 3a prepared in the sludge mixing tank A ₁ is conveyed through the pipe p ₃ and continuously supplied to the belt press dehydrator B. In the belt press dehydrator B, a pair of filter cloths 1a, 1b
Circulates in the caging 2 at a predetermined traveling speed by the filter cloth drive motor M ₄ . The coagulated sludge 3a supplied from the pipe p ₃ to the gravity dehydration section B ₁ is gravity-filtered while being conveyed by the filter cloth 1a traveling in the direction of arrow q. Then, the formed filtrate sandwiched is filter cloth 1b, the whole passes through a pressurized dehydration section B _2, is squeezed and dewatered in the process progresses.

The water content of the dehydrated cake 3b which has passed through the pressure dehydration section B ₂ and is scraped off from the filter cloth is measured by the water content meter C. As the water content meter C used at this time, for example, the dehydrated cake 3b is sampled in a sample dish, heated and dried from above to measure the weight change of the dehydrated cake, and the water content of the dehydrated cake is determined from the weight change. An example of the heat-drying type moisture meter thus prepared can be given.

The signal of the measured value obtained by the water content meter C is input to the arithmetic and control unit D. The measured value of the water content input from the water content meter C to the arithmetic and control unit D every moment is
Each time, it is compared and calculated with the target value of the water content stored in the arithmetic and control unit D. When the measured value of the water content is lower than the target value, either the dehydration time is too short or the amount of admixture of the pulverized waste paper is too small. A control signal for increasing the traveling speed of the filter cloth is output to the motor M ₄ to control the traveling speed of the filter cloth, or the slurry injection pump P ₂
A control signal for increasing the supply amount of the crushed waste paper slurry 8 is output to control the mixing amount of the crushed waste paper into the sludge.

By repeating the above operation,
The water content of the dehydrated cake 3b discharged from the belt press dehydrator B reaches a target value of the water content stored in the arithmetic and control unit D, that is, a constant state. In addition,
In the present invention, the controlled objects are the traveling speed of the filter cloth and the amount of the crushed waste paper mixed into the sludge, and the former of the objects is the traveling speed of the filter cloth with respect to the control signal from the arithmetic and control unit D. Since the response is fast, it can be said to be a suitable control target.

At that time, when it is calculated that the traveling speed of the filter cloth must be slower than the lower limit value (0.5 m / min) of the operating condition of the belt press dehydrator B, the crushed waste paper is used. Operation controller D to increase the amount of sewage mixed with sludge
Output the control signal from the slurry injection pump P ₂ to the slurry injection pump P _2. On the contrary, the traveling speed of the filter cloth must be made higher than the upper limit value (2.0 m / min) of the operating conditions of the belt press dehydrator B. When the calculation is performed as described above, a control signal may be output from the calculation control device D to the slurry injection pump P ₂ so as to reduce the amount of the crushed waste paper mixed with the sludge.

[0049]

As is clear from the above description, according to the method and apparatus of the present invention, even if the concentration and properties of the sludge to be treated are changed, the water content of the dehydrated cake obtained can reach the self-burning range. It can be lowered and stabilized. Therefore, the dehydrated cake obtained by the method and apparatus of the present invention can be incinerated with a small amount of auxiliary fuel, and the operating conditions of the incinerator can be easily managed.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the water content ratio of coagulated sludge and the pressing time in Experiment (1) of the present invention.

FIG. 2 is a graph showing a relationship between a filter cloth running speed of a belt press dehydrator and a water content of a dehydrated cake in a verification test for sludge at an S treatment plant.

FIG. 3 is a schematic diagram showing the basic configuration of the device of the present invention.

FIG. 4 is a schematic view showing a belt press dehydrator.

[Explanation of symbols]

A Means for preparing coagulated sludge A ₁ Sludge mixing tank A ₂ Sludge supply tank A ₃ Waste paper dispersion tank A ₄ Coagulant storage tank B Belt press dewatering machine B ₁ Gravity dewatering section B ₂ Pressurized dewatering section C Water content meter D Calculation control device 1a, 1b Filter cloth 2 Caging 3 Sludge 3a Coagulated sludge 3b Dehydrated cake 4,4a Roller 5a, 5b, 5c Stirrer 6 Hopper of crushed waste paper 7 Measuring tank of crushed waste paper 8 Slurry of crushed waste paper M ₁ , M ₂ , M ₃ drive motor M ₄ filter cloth drive motor p ₁ , p ₂ , p ₃ piping P ₁ sludge pump P ₂ slurry injection pump

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kozaburo Akamatsu 2-6-2 Otemachi, Chiyoda-ku, Tokyo Within Tokyo Sewer Service Co., Ltd. (72) Inventor Yasuhiro Oi 3-4 Nishi-Shinjuku, Shinjuku-ku, Tokyo No. 7 Kurita Industry Co., Ltd. (72) Inventor Junichi Yoshiki 3-4-7 Nishishinjuku, Shinjuku-ku, Tokyo Inside Kurita Industry Co., Ltd.

Claims (2)

[Claims] 1. A belt press type equipped with a filter cloth that mixes a coagulant and a pulverized product of waste paper into sludge to form coagulated sludge, and the coagulated sludge is circulated between a gravity dehydration section and a pressure dehydration section. When supplied to a dehydrator for dehydration, the water content of the obtained dehydrated cake is measured, and based on the measured value, the water content of the dehydrated cake shows a value within a predetermined range. A method for dehydrating sludge, which comprises controlling an admixing amount of pulverized material and / or a traveling speed of the filter cloth. 2. A means for admixing a coagulant and a crushed product of waste paper into sludge to form coagulated sludge; a belt press type dehydrator for dehydrating the coagulated sludge; a water content of the dehydrated cake discharged from the belt press type dehydrator. A moisture content meter for measuring the rate; and a signal for inputting an output signal of the moisture content meter, calculating the output signal, and controlling a filter cloth running speed of the belt press type dehydrator and mixing of the pulverized waste paper. A sludge dewatering device, comprising: an arithmetic and control unit that outputs a signal for controlling the amount.