JP3220874B2 - Sludge dewatering method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention improves the water permeability of coagulated sludge in the treatment of sludge such as sewage sludge, tap water sludge, bottom sludge, construction sludge, industrial waste sludge, tidal river sludge, and harbor sludge. And a method for facilitating sludge dewatering and volume reduction by mechanical dewatering and civil dewatering.

[0002]

2. Description of the Related Art Such sludge is composed of fine particles, and even if flocculated and flocculated, the dewatering property from the floc is poor, making it extremely difficult to dewater and reduce the volume of sludge. In other words, as for sludge, an example of sludge is described. When dredging and disposing of sludge, a method of mixing cement-based material with sludge and solidifying the sludge is generally employed. In addition, it was difficult to neutralize.

[0003] When dewatering and reducing the volume of sludge, since sludge contains impurities such as stones, glass fragments, relics, and string-like materials, a filter press, a belt press, and a centrifugal dehydrator are used. In such cases, economical dehydration could not be achieved.

[0004] In view of the above, the present invention provides a method for dewatering and reducing the volume of sludge, which can be effectively dewatered by a mechanically robust screw dehydrator having a coarse mesh. The purpose is to:

[0005]

SUMMARY OF THE INVENTION The present invention has been devised to solve the above-mentioned problems, and it is said that the water permeability of coagulated sludge can be improved by adding a specific coagulant and a specific crystallization agent to the sludge. It was completed with knowledge.

[0006] That is, the first method of the sludge dewatering treatment according to the present invention is used for dewatering and reducing the volume of sludge.
The present invention is characterized in that a natural polymer flocculant and a lime-based acicular crystal agent are added to the sludge.

Further, in the second sludge dewatering method of the present invention, when dewatering and reducing the volume of river sludge or harbor sludge in a tidal zone, a natural polymer flocculant, an alumina cement-based coagulant and lime are added to the sludge. A needle-like crystallization agent is added.

The natural polymer coagulants include polysaccharide-based coagulants (CaO, Na ₂ O, SiO ₂ , SO
₃ etc.) are preferably used.

As the lime-based acicular crystal agent, those containing CaO as a main component and containing SiO ₂ , MgO, Fe ₂ O _{3 and the} like are preferably used.

The natural polymer flocculant and the lime-based acicular crystallization agent may be added separately to the sludge, or two of them may be added to the sludge as a single agent.

The sludge pumping method includes (i) dredging with a pump and (ii) dredging with a gram shell (bucket). In pump dredging (i), since the concentration of sludge is low,
As a pretreatment of sludge with a dehydrator, the sludge is coagulated and precipitated, and a natural polymer flocculant and a lime-based acicular crystal agent are added to the sludge and mixed.

On the other hand, (ii) the sludge picked up by the gram shell (bucket) is considerably concentrated, so that a natural polymer flocculant and a lime-based needle-like crystallizing agent are added and mixed to create conditions that facilitate dehydration. There are things you can do.

In the first sludge dewatering method, the water content is 50%.
To a general sludge of about 0% or less, a natural polymer flocculant and a lime-based acicular crystal agent are added as two agents separately or as a mixture.

In the second sludge dewatering method, a natural polymer flocculant, an alumina cement-based coagulant and a lime-based needle-shaped crystal agent, three agents separately or mixed are added to tidal river sludge or port sludge. Add as

The treated sludge thus obtained coagulates and solidifies and changes from a liquid state to a plastic state. Even when the sludge is put into water, solid-liquid separation can be carried out at an early stage and mud does not occur. Further, even if the treated sludge is stirred and then put into water, mudification does not progress. When this treated sludge is dehydrated with a screw dehydrator, the dehydrated filtrate can be separated and the sludge can be reduced in volume.

The speed of the dehydration depends on the degree of water permeability of the sludge that has been coagulated and solidified into a plastic state, that is, the type of bonding between the coagulated particles. In order to improve water permeability, it is important that the crystals of the particles are needle-like crystals so that the filtrate can easily pass therethrough, and it is necessary that the crystals have a strength that does not cause the crystals to break in dewatering by pressing.

According to the treatment method of the present invention, the aggregated sludge crystals are converted into needle-like crystals, so that the treated sludge obtained has good water permeability, and can be used for mechanical dehydration (dehydration while containing impurities) and It can also deal with civil engineering dehydration (dehydration by laminating in soil and layers).

The above description is for the case where the sludge is sludge, but the sludge dewatering method of the present invention can of course be applied to sludge other than sludge.

In the sludge dewatering method of the present invention, when adjusting the pH of the treated sludge, an appropriate amount of an acid or alkali is added. Also, to promote solidification after dehydration,
It is advisable to add a solidifying agent separately. Further, when the sludge dewatering method of the present invention is repeated a plurality of times, more preferable results are obtained.

[0020]

According to the first sludge dewatering method of the present invention, a natural polymer flocculant and a lime-based acicular crystallizing agent are added to sludge.
In the second sludge dewatering method, a natural polymer flocculant, an alumina cement-based coagulant and a lime-based acicular crystallizer are added to tidal river sludge or port sludge, so that they are coagulated and solidified into a plastic state. The sludge crystals are made into needle-like crystals. Therefore, the obtained treated sludge shows good water permeability, and can cope with mechanical dehydration (dehydration while containing contaminants) and civil dehydration (dehydration by laminating in soil and layers).

[0021]

EXAMPLE A natural polymer flocculant, an alumina cement-based coagulant and a lime-based acicular crystal were added to three types of sludge having the properties shown in Table 1, respectively, in the amounts shown in Table 1.

Then, the treated sludge was dehydrated with a screw dehydrator, and the water content of the sludge after dehydration was determined. This value is shown in Table 1.

[0023]

[Table 1] From the results in Table 1, it is recognized that sludge can be easily dehydrated and reduced in volume by the method of the present invention.

[0024]

(1) In pump dredging of sludge or the like in which low-concentration fine particles are suspended, a natural polymer condensing agent is added as a flocculating solidifying agent to the flocculated and treated sludge, and a lime-based needle-like crystallizing agent To make the sludge plastic,
The bonding of the particles is made into a needle-like crystal, whereby the water permeability can be improved and the crystal strength can be enhanced. As a result, the obtained treated sludge can be easily subjected to mechanical dewatering and civil dewatering.

(2) Since the treated sludge can be sufficiently dehydrated even at normal temperature, there is no odor or the like generated at the time of heating, which is advantageous in environmental measures and energy saving.

(3) The natural polymer flocculant, the alumina cement-based coagulant and the lime-based acicular crystallizer are all in powder form, and absorb water when added to sludge, and are therefore preferable in the treatment system.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Masakazu Kashihara, Inventor 5--3-28 Nishikujo, Konohana-ku, Osaka-shi Inside Tachibana Shipbuilding Co., Ltd. (72) Inventor Toshihiro Yamano 5-28, Nishikujo, Konohana-ku, Osaka-shi No. Tachi Shipbuilding Co., Ltd. (72) Inventor Hiroshi Ishige 2-9-1-9, Noribori, Nishi-ku, Osaka-shi Ataka Kogyo Co., Ltd. (72) Takao Okura 2-1-1, Tachibori, Nishi-ku, Osaka-shi Ataka Kogyo (56) References JP-A-4-40287 (JP, A) JP-A-60-255200 (JP, A) JP-A-59-147700 (JP, A) (58) Fields investigated (Int. Cl. ^7, DB name) C02F 11/14

Claims (2)

(57) [Claims] 1. A method for dewatering sludge, comprising adding a natural polymer flocculant and a lime-based acicular crystallizing agent to the sludge for dewatering and reducing the volume of the sludge. 2. Dewatering of tidal river sludge or harbor sludge.
A sludge dewatering method comprising adding a natural polymer flocculant, an alumina cement-based coagulant, and a lime-based acicular crystal agent to the sludge for volume reduction.