JP2001062500A - Dehydrating method using carbonate sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the water content in a dehydrated cake and to decrease the quantity of the cake generated by carbonating sewage sludge, mixing the carbonated sludge having prescribed particle diameter with sewage sludge to be dehydrated and supplying a high molecular flocculant with the mixture to a centrifugal dehydrator or a belt type dehydrator to dehydrate. SOLUTION: The concentrated sludge 1 is stored in a sludge storing vessel 2 and the carbonated sludge 3 is added thereinto in a prescribed ratio. The concentrated sludge 1, in which the carbonated sludge 3 is added, is supplied to a centrifugal dehydrator 5 by a crushing pump 4. A polymer 6 of the high molecular flocculant is added into the centrifugal dehydrator 5 in a prescribed ratio. The carbonated sludge 3 acts as a nucleus at the time of forming floc in the flocculation of the sewage sludge by the polymer 6 to form large floc and to increase the flocculation effect. Because the flocculation effect is increased by the action of the carbonated sludge 3 in the centrifugal dehydrator 5, the sludge is easily settled and the dehydration property is improved, the water content in the dehydrated cake 7 is decreased and the stripping property to the filter cloth is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technology for dewatering sewage sludge in a sewage treatment plant, and to a dewatering method using carbonized sludge obtained by carbonizing sewage sludge.

[0002]

2. Description of the Related Art Conventionally, sewage sludge generated in a sewage treatment plant has been subjected to a melting treatment of a part of a dewatered cake after dehydration in a melting furnace to form a molten slag for effective use.
The entire amount of sewage sludge cannot be melted and most of it is landfilled as dewatered cake. However, in recent years, it has become difficult to secure a final disposal site, and there is an urgent need to reduce and stabilize sludge, and there is an urgent need to promote the effective use of sewage sludge.

[0003]

In the dewatering treatment of sewage sludge, a polymer flocculant is added to sewage sludge as a dewatering aid in a centrifugal dewatering machine and a belt press to dewater. Table 1 shows the performance of this dehydrator and the water content of the dehydrated cake.
(Centrifugal dehydrator), as shown in Table 2 (belt press).

[0004]

[Table 1]

[0005]

[Table 2] However, there was a problem that the water content of the cake could not be reduced to 78% or less using only the conventional polymer flocculant. An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a dewatering method using carbonized sludge that can reduce the water content of a dewatered cake and reduce the amount of cake generated by reducing the water content.

[0006]

In order to solve the above-mentioned problems, a dewatering method using carbonized sludge according to the present invention is characterized in that sewage sludge is carbonized to form carbonized sludge, and the carbonized sludge having a predetermined particle size is subjected to dehydration. Is added to sewage sludge and mixed, and a polymer flocculant is supplied to a centrifugal dehydrator or a belt press dehydrator together with the mixture to be dehydrated.

[0007] With the above-described structure, carbonized sludge acts as a nucleus when flocs are formed during flocculation of sewage sludge by a polymer flocculant, and forms large flocs to enhance the flocculating effect. For this reason, the dewatering property can be improved and the water content of the dewatered cake can be reduced, and the amount of dewatered cake generated can be reduced by reducing the water content. Further, the dewatered cake can be deodorized by the adsorption ability of the carbonized sludge to reduce the original odor concentration, and the clarity of the dehydrated filtrate can be increased.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, concentrated sludge 1 is obtained by treating sewage by an oxidation ditch, storing the treated sewage in a concentration tank, and then concentrating by gravity sedimentation. This concentrated sludge 1 is stored in a sludge storage tank 2, and carbonized sludge 3 is added at a rate of 10 to 30% based on sludge solids. It is more effective to add the carbonized sludge 3 when the sludge is added about the day before dehydration. The concentrated sludge 1 to which the carbonized sludge 3 has been added is supplied to a centrifugal dehydrator 5 by a crushing pump 4.

[0009] To the centrifugal dehydrator 5, a polymer 6 as a polymer flocculant is added at a ratio of 0.5 to 1.2% based on sludge solids. At this time, at the time of flocculation of sewage sludge by the polymer 6, the carbonized sludge 3 acts as a nucleus at the time of floc formation,
Form large flocs to enhance coagulation effect. Therefore, the carbonized sludge 3 is preferably in the form of particles having a particle size of about 1 to 5 mmφ.

In the centrifugal dewatering machine 5, the effect of the carbonized sludge 3 enhances the coagulation effect, so that the sludge is liable to settle, the dewatering property is improved, and the water content of the dewatered cake 7 can be reduced. The presence of the sludge particles improves the releasability of the filter cloth. A part or all of the dewatered cake 7 is put into a carbonization furnace (not shown) and carbonized, and the generated carbonized sludge 3 is circulated and used as a dewatering property improving agent.

Table 3 shows the conventional structure and the carbonized sludge 3 of the present invention.
Is shown in comparison with a configuration in which is added as a dehydration improver.

[0012]

[Table 3] In Table 3, the sludge amount per dewatered cake was increased by 1.2 times by the introduction of the carbonized sludge 3, but the water content of the cake was reduced to 65 to 70% by the improvement of the dewatering property by the carbonized sludge 3. As a result, the amount of dewatered cake 7 generated can be reduced. By using a part of the dewatered cake 7 as a raw material of the carbonized sludge 3, the amount of cake to be carried out can be reduced,
When the entire amount of the dewatered cake 7 is used as a raw material of the carbonized sludge 3, the amount of cake to be carried out is eliminated, and the carbonized sludge 3 can be stored as a valuable material such as fuel. The carbonized sludge 3 exhibits a deodorizing effect due to its adsorption ability, and can obtain a removing effect of hydrogen sulfide: 90% or more, methyl sulfide: 50% or more, methyl mercaptan: 80% or more. Since the amount decreases, the effect of reducing the amount of the deodorizing agent used in the post-process and extending the life of the activated carbon can be obtained. In addition, BOD and CO in the dehydrated filtrate are determined by the adsorption capacity of the carbonized sludge 3.
As the D concentration decreases, BO in the water treatment of the dehydrated filtrate is reduced.
D load can be reduced.

As shown in FIG. 2, the concentrated sludge 1 to which the carbonized sludge 3 has been added in the sludge storage tank 2 is supplied to a belt press dewatering machine 8 together with a polymer 6 which is a polymer flocculant, and may be dewatered. it can. Also in this case, the polymer 6 is added at a ratio of 0.5 to 1.2% based on the sludge solids. Table 4 shows a comparison between a conventional configuration and a configuration in which the carbonized sludge 3 of the present invention is added as a dewatering property improving agent.

[0014]

[Table 4]

[0015]

As described above, according to the present invention, the carbonized sludge acts as a nucleus at the time of floc formation and enhances the coagulation effect, so that the dewaterability is improved and the water content of the dewatered cake can be reduced. The amount of dewatered cake generated can be reduced by reducing the water content. Further, the dewatered cake can be deodorized by the adsorption ability of the carbonized sludge to reduce the original odor concentration, and the clarity of the dehydrated filtrate can be increased.

[Brief description of the drawings]

FIG. 1 is a dehydration flow sheet according to an embodiment of the present invention.

FIG. 2 is a dehydration flow sheet according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Condensed sludge 2 Sludge storage tank 3 Carbonized sludge 4 Crushing pump 5 Centrifugal dehydrator 6 Polymer 7 Dehydration cake

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroaki Miwa 1-811 Hakusan, Moriyama-ku, Nagoya-shi, Aichi Prefecture (72) Inventor Sachi Fujiwara 31 Miyano-mae, Kuzuoka, Ouchi-cho, Yuri-gun, Akita Prefecture (72) Inventor Eiichi Shoko 48-8 Shinonome-cho, Toyoura-cho, Abuta-gun, Hokkaido (72) Inventor Yoshio Akazawa 2-8-34 Miyamoto, Urawa-shi, Saitama (72) Inventor Tetsuji Masaki 8-25-13 Maison A, Itabashi-ku, Tokyo Jules 205 (72) Inventor Kenichi Ude 2-4-147 Shizitsuhigashi, Naniwa-ku, Osaka-shi

Claims (1)

[Claims] Claims: 1. Sewage sludge is carbonized to produce carbonized sludge,
The carbonized sludge having the predetermined particle size is added to and mixed with the sewage sludge to be dewatered. Dehydration method used.