JPH0771680B2 - Sludge dewatering method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to sludge dehydration in which sludge is coagulated by adding a cationic polymer coagulant and then gravity dehydrated, and gravity dehydrated dehydrated sludge is further forcedly dehydrated. Regarding processing method.

[Conventional technology]

In the conventional sludge dewatering method, odor is easily generated from sludge and dewatered sludge, to deteriorate the environment during storage and transfer of sludge and incineration, slaked lime to deodorize sludge,
It has been considered to add to the sludge before or simultaneously with the addition of the polymer flocculant.

[Problems to be solved by the invention]

However, while the cationic polymer flocculant works effectively on sludge at pH 5-9, even if the minimum amount of slaked lime required for deodorizing sludge is added, the sludge will be almost at pH.
Therefore, only small flocs can be formed, which not only lowers the dehydration efficiency, but also dissolves slaked lime in the water, so when sludge is gravity dehydrated, the slaked lime added to the sludge is filtered. There is a problem that it is necessary to increase the amount of slaked lime added in order to maintain a sufficient sludge deodorizing effect by dissolving in it and flowing out.

An object of the present invention is to deodorize sludge without deteriorating the aggregating function of the cationic polymer aggregating agent.

[Means for Solving Problems] The characteristic means of the sludge dewatering treatment method of the present invention is to dehydrate sludge, to deodorize by adding slaked lime, and then to perform forced dehydration. Is the street.

[Work]

In other words, the sludge before addition of slaked lime is aggregated by the addition of the cationic polymer flocculant to form large flocs, and the water liberated between the large flocs by gravity dehydration is efficiently and sufficiently dehydrated to reduce the water content. By adding slaked lime to the dehydrated sludge, slaked lime rarely dissolves in the filtrate, and since the dehydrated sludge retains sufficient water for deodorization, it is possible to sufficiently deodorize the dehydrated sludge. it can.

〔The invention's effect〕

Therefore, since slaked lime is added after the formation of flocs, the sludge can be deodorized without deteriorating the coagulation function of sludge by the cationic polymer coagulant, and the dehydration work can be performed efficiently without deteriorating the sludge treatment environment. became.

Moreover, since the amount of slaked lime that elutes in the filtrate is small, the amount of slaked lime used for deodorizing sludge can be reduced, which improves economic efficiency and is added to dehydrated sludge with low water content. Moreover, since slaked lime has a larger particle size than sludge, it has become possible to further improve the dehydration efficiency of forced dehydration as a dehydration aid.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 2, a mixer (3) for aggregating and mixing the object to be treated supplied from the first reservoir (1) and the cationic polymer flocculant supplied from the second reservoir (2). ),
Between the endless belt-shaped first rotating filter cloth (4) and the case side wall (5) and the partition wall (6), the coagulation-treated product from the kneading machine (3) is supplied to perform self-weight filtration of water. While forming the gravity dehydration section (7), the sludge cake sent out on the first rotation filter cloth (4) is sent to the gravity dehydration section (7) on the lower side in the rotating direction of the filter cloth (4). A thickness adjusting roll (8) for adjusting the thickness is provided, and on the lower side thereof, a second rotating filter cloth for pressing the thickness-adjusted cake between the first rotating filter cloth (4). (9) is provided, and the thickness dewatering zone (A) of a straight path and the compression dewatering zone (B) of a large-diameter circular arc path are provided.
And, the forced dehydration part (10) formed of the meandering path (C) is formed, and accordingly, with the rotation of the first filter cloth (4) from the gravity dehydration part (7) to the forced dehydration part (10), The belt press type dehydrator is configured to continuously dehydrate the object to be treated such as sludge generated by various water treatments such as human waste, municipal sewage or industrial wastewater. Rolls (8) for deodorizing sludge from
An addition device (12) for adding slaked lime to gravity-dehydrated dehydrated sludge is arranged in front of the.

That is, when dewatering sludge, the deodorizing method for sludge will be explained step by step with the block diagram of FIG. 1. Sludge is flocculated by adding a cationic polymer flocculant, and then gravity dehydration is performed. Slaked lime is added to the dehydrated dehydrated sludge to deodorize the sludge, and the dehydrated sludge is further forcedly dehydrated.

The above-mentioned polymer flocculant is 0.5 to 1.5 wt% and forms flocs of 1 mm to 5 mm, and at least 3 to 5% of slaked lime is added for deodorizing sludge. The deodorizing nature.

[Another embodiment]

The slaked lime added to the dehydrated sludge may be in the form of powder or in the form of a solution, and may be added immediately after the thickness adjusting roll (8).

In order to perform the forced dehydration, a centrifugal dehydrator or the like may be used instead of the belt press type dehydrator.

A stirrer may be provided at a location where slaked lime is added before the thickness adjusting roll (8) in order to improve mixing of the dehydrated sludge and slaked lime.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

Drawing shows an example of a sludge dewatering method according to the present invention,
FIG. 1 is a block diagram showing the entire processing method, and FIG. 2 is a schematic side view of a belt press type dehydrator.

Claims (1)

[Claims] 1. A sludge dewatering method for coagulating sludge by the addition of a cationic polymer coagulant, followed by gravity dehydration, and forced dehydration of gravity dehydrated dehydrated sludge. A sludge dewatering treatment method in which the above is added to deodorize and then the above-mentioned forced dewatering is performed.