JPS61268400A - Method for modifying sludge for dehydration - Google Patents

Abstract

PURPOSE:To enhance dehydration capacity, by separating the fibrous substance in raw sludge generated from the first sedimentation basin of a sludge treatment process to add the same to excessive activated sludge. CONSTITUTION:A fibrous substance 10 is separated from the raw sludge 8 in a first sedimentation basin 3 by a fibrous substance separation apparatus 9. The sludge 11 after separation is converted to digestion sludge 13 in a digestion tank 12 and the fibrous substance 10 is mixed with the digestion sludge 13 by a mixer 14. The fibrous substance added digestion sludge 15 is applied to a belt press type dehydrator 16 to be dehydrated. The amount of the fibrous substance 10 to be added is set to 2-4wt. times the fibrous substance of digestion sludge of excessive activated sludge. By this method, dehydration capacity is enhanced and the release of a dehydrated cake from filter cloth is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for reforming dewatering sludge for effectively dewatering sewage sludge.

[Conventional technology]

Belt press type dewatering machines normally have different levels of cake moisture, slush overspeed,
The dehydration performance differs depending on the peelability.

Types of sewage sludge are generally divided into raw sludge generated from the initial settling tank, surplus activated sludge generated from the final settling tank, and digested sludge drawn from the digestion tank. Due to the decomposition of organic matter and the miniaturization of particles, the amount of fibrous material is reduced compared to the raw sludge before being put into the digester.

Fibrous substances generally have a large effect on the dewatering performance of a belt press type dehydrator, and the above-mentioned digested sludge, which has a small amount of fibrous substances, often has inferior dewatering performance compared to raw sludge.

In addition, surplus activated sludge has a large amount of organic content and a small amount of fibrous substances, so it is usually difficult to dehydrate it alone.

When dewatering digested sludge or surplus activated sludge, which is difficult to dewater, conventionally, measures were taken by increasing the addition rate of flocculant or reducing the amount of treatment, or by using cationic and anionic sludge.
Measures are being taken to maintain dehydration performance by using different types of flocculants.

On the other hand, there is also an example of a method in which a cationic polymer flocculant and pulp are mixed and added to sludge (Japanese Patent Application Laid-open No. 59-1999).
-87097).

[Problem that the invention seeks to solve]

However, in such a method, the flocculant is obtained from outside the system, which increases running costs and is not a good idea.The present invention solves the above-mentioned conventional problems. The present invention provides a method for significantly improving dewatering performance without increasing running costs.

[Means for solving problems]

The present inventors focused on the fact that raw sludge contains many fibrous substances that have a large effect on dewatering performance. It has been found that the dewatering performance of a belt press type dewatering machine can be significantly improved by adding it to sludge. This method is characterized by separating and recovering fibrous substances in sludge and adding them to surplus activated sludge or digested sludge.

[Effect]

In the present invention, fibrous substances in raw sludge are separated and recovered.
is added to surplus activated sludge or digested sludge. Therefore, since a fiber component is added to the sludge, it exhibits good dewatering performance. [Specific Examples of the Invention] The present invention will be explained in more detail below.

Figure 1 shows the sludge treatment process including the method of the present invention.
The inflowing sewage 1 flows into the settling basin 2.

Here, after the coarse particles are settled fL*, they are first led to a settling tank 3, then passed through an aeration tank 4 and a final settling tank 5, where they are cleaned and then discharged.

Surplus activated sludge 6A, 6B from the final settling tank 5 is returned to the first settling tank 3 and the aeration tank 4. On the other hand, in the present invention, the surplus activated sludge is returned to the first settling tank 3, preferably through the thickening tank 7. Fibrous substances 10 are separated from the sludge 8 by a fibrous substance separator 9, such as a screen or vibrating sieve. The sludge 11 after separation is made into digested sludge 13 in a digestion tank 12, this digested sludge 13 is mixed with fibrous material 10 in a mixer 14, and this fibrous material-added surplus sludge 15 is transferred to a belt press type dehydrator 1.
6 to dehydrate. 17 is a dehydrated cake.

On the other hand, the fibrous material 10 is mixed in the mixer 18 with surplus activated sludge 6C;
6 for dehydration.

It is also within the scope of the present invention to add a fibrous substance to both the digested sludge and surplus activated sludge for dewatering.

By the way, it is necessary to add the separated and recovered fibrous substances in a state in which water is removed as much as possible, and after addition, it is necessary to thoroughly stir the fibrous substances and disperse them in the sludge. As for the timing of addition, it is best to add the organic polymer flocculant to the sludge and mix it with the sludge before forming coagulated flocs, and the effect will be less after the flocs are formed.

As for the amount added, the dehydration performance improves as the amount added increases, but adding too much is not efficient, so
Usually, the fibrous material of digested sludge or surplus activated sludge is
4 times the weight is preferable [Example] Next, the effects of the present invention will be clarified with examples 0 In the following examples, the fibrous material is
It is defined as coarse suspended solids that can be separated with a mesh or 80 mesh sieve, and the addition ratio was set based on the ratio of this coarse suspended solid to the amount of solids in the sludge (Example 1) Solids concentration Section 3.4, organic content 53.84%, crude suspended matter 4
．． 78% crude protein and 24.78% crude protein, 100 mesh coarse suspended matter in raw sludge was added to the digested sludge at a rotation speed of 150 rpm so that the concentration of crude suspended matter after addition was 2 to 3 to 4 times.
While stirring, add the methacrylic acid ester-based 4-metal salt polymer to the solids in an amount that makes the total solids 518.1 g per 100i of molten area while maintaining the same rotation speed.
Inject and allow to flocculate for 90 seconds. Then r over area 100
Gravity flow 1 on the f cloth of d for 120 seconds, and a load of 0.02 kg/CI for another 120 seconds? Preliminary pressure was applied so that the pressure was L. The same fabric as the previous one was placed on top of the pre-pressurized cake, and a dehydration test was conducted using a table tester manufactured by Lapisho Kikai Co., Ltd.

Items measured included cake moisture per gravity, dehydrated cake moisture, and dehydrated cake spread. The test results were as shown in Table 1.Table 1 Note 1) The additive was 100 mesh coarse suspended matter.Note 2) The area magnification of the cake spread was 100cr1. To.

0 (Example 2) Example 2: Digested sludge with a solid concentration of 2.96%, an organic content of 53.55%, a crude suspended matter of 4.15%, and a crude tanno-crystalline substance of 23.4-2%. Instead of 100 mesh coarse floating matter of 1, 8
0 mesh coarse suspended solids are digested sludge coarse suspended solids concentration 3,4
The dehydration test was carried out in the same manner as in Example 1.The results are shown in Table 2, and the same effect as 100 mesh was observed.Table 2 Note 3) The additive provided 80 mesh of coarse suspended matter. (Discussion) According to the above examples, as shown in Tables 1 and 2, the dewatering performance was improved by adding fibrous substances in raw sludge. [Effect of the Invention] As described above, according to the present invention, since the fibrous material separated and recovered from raw sludge is added to excess activated sludge or digested sludge, the dewatering performance is improved. For example, compared to the conventional method, the dehydrated cake moisture is reduced by about 5 factors, the cake moisture per gravitational force is reduced by about 2φ, and the releasability from cloth is improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of sewage treatment according to the method of the present invention. 3. Initial settling tank 5. Final settling tank 6A to 6C...
Surplus activated sludge 8. Raw sludge 9. Separation device 10
... Fibrous material 12 ... Digestion tank 13 ... Digested sludge 16 ... Dehydrator procedure amendment (voluntary) July 5, 1985 Patent application No. 109651 No. 109651 2 Title of invention Improvement of sludge for dewatering Quality method 3 Relationship between the person making the amendment and the case Patent applicant 4 Agent 〒101 5 Date of amendment order Voluntary amendment 6 Drawing to be amended 7 Contents of amendment

Claims (1)

[Claims] (1) When dewatering sewage sludge, fibrous substances in raw sludge generated from the initial settling tank of the sludge treatment process are separated and recovered, and added to surplus activated sludge or digested sludge. Modification method.