JPS60143900A - Concentration device for sludge - Google Patents

Abstract

PURPOSE:To concentrate excess sludge withdrawn from a final settling basin economically by feeding a layer of concentrated sludge by floatation and a layer of concentrated sludge by settling to a centrifugal concentrator, and feeding the mixture of the separated water and the excess sludge to the centrifugal concentrator. CONSTITUTION:A layer of floated solid matters is mixed or collected in a sludge collecting box 3d provided to an intermediate chamber Q, and then enters an external box 3e. On one hand, settled sludge is withdrawn by a pump 4 from the bottom 3c, combined with the sludge withdrawn by a pump 5 from the external box 3e and enters a tank 6. The sludge in the tank 6 is withdrawn by a pump 7 and fed to a centrifugal concentrator 8. On the other hand, an intermediate clear layer contg. only small amt. of solid matters interposed between the floated solid matters layer and the settled sludge layer is discharged through a conduit pipe 9 and fed back to a filthy water treatig facility. The solid matter content of the intermediate water in this stage is reduced to less amt. than the content of solid matter in the separated water immediately after it is discharged from the centrifugal concentrator 8.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a sludge concentrator for concentrating surplus sludge generated during sewage treatment using the activated sludge method.

(Background Art) There are various variations of the activated sludge method, but as shown in Figure 1, a typical example is that sewage to be treated usually first enters settling tank A to collect raw sludge. After sedimentation and separation, return sludge is added, then enters the aeration tank B, where air (oxygen) is blown in to maintain an aerobic atmosphere, and the sewage and sludge are in a suspended state and in close contact. , biodegradation of sludge by aerobic microorganisms takes place. The wastewater is further transferred to the final settling tank C.
The sludge is then allowed to stand still and the sludge is sedimented and separated, but a portion of it is returned to the aeration tank B as return sludge, and the remainder is pulled out as so-called surplus sludge. The supernatant water is discharged as treated water (some treatment devices omit the initial settling tank A).

The present invention relates to an apparatus for treating excess sludge.

In conventional methods, excess sludge is usually dehydrated and concentrated using a centrifugal thickener as illustrated in FIG.

First, to explain the centrifugal concentrator shown in Fig. 2, the left end of the hollow cylindrical casing E (the right side part is conical) has a concentric opening F in the center, and the annular end plate G has a concentric opening F in the center. The center of the side end forms a separated water outlet i[H. Inside the casing E, there is a rotating body K in the form of a screw conveyor.
are provided for concentric rotation. The sludge is fed into the casing E from the left end of the figure, rotated by a rotating body K, and forms a liquid level M. Separated water near the center and therefore having a low specific gravity is discharged over the weir H in the direction of the thin arrow, and concentrated sludge near the inner surface of the casing E is sent by screw N to the right as shown by the bold arrow. and is ejected from the right end. It goes without saying that the centrifugal concentrator of the present invention is not limited to this example. For economical reasons, the centrifugal effect of this type of circular core shrinking machine is desirably about 800 to 2,000, and the separated water contains 10 to 2 of the solid content in the sludge.
Usually it contains 0% by weight. Therefore, this separated water cannot be released as it is, and conventionally, the first sedimentation tank A
Otherwise, the water is normally returned to the aeration tank B, which significantly reduces the efficiency and capacity of the sewage treatment system as a whole.

(Object of the Invention) In view of the above circumstances, an object of the present invention is to provide a more economical thickening device t for excess sludge drawn out from the final settling tank of a sewage treatment device using an activated sludge method.

More specifically, it is an object of the present invention to achieve a
Sludge can be pre-concentrated and separated water can be reprocessed at the same time. The object of the present invention is to provide an economical thickening device for surplus sludge.

(Structure and operation of the invention) In FIG. 3 showing an embodiment of the present invention, the excess sludge shown in FIG.
After mixing with separated water from the centrifugal concentrator, the water is sent to the separation tank (3). The separation tank (3) is a tank with a rectangular, circular, or other appropriate shape in horizontal cross section, and has partition walls 3a, 3
b, it is divided into an inner chamber P, an intermediate chamber Q1, and an outer chamber R with the lower part open.

The mixed sludge water is sent from the conduit (4) to the inner chamber P of the separation tank (3). Some of the suspended solids in the introduced sludge water float to the surface and form a floating solids layer, while some of them settle to form a separated sludge layer and accumulate at the bottom (3c). The floating solid layer overflows or collects mud in a mud collection box (3d) provided in the intermediate chamber Q, and enters the outer box (3e). On the other hand, the settled sludge is pulled out from the bottom (3c) by the pump (4) and placed in the outer box (3e).
) is combined with the sludge drawn out by the pump (5),
Enter the storage tank (6). At this time, the excess sludge is 1 to 2% by weight.
Therefore, the volume has been reduced. The sludge in storage 4 (6) is pumped (
7) and placed in a centrifugal concentrator (8).

On the other hand, the intermediate excretory layer between the floating solids layer and the settled sludge layer, which has few solids, is discharged through the conduit (9) and returned to the sewage treatment plant. The intermediate water at this time has less solid content removed than the separated water immediately after being discharged from the centrifugal concentrator.

In the case of this example, for example, the solid content is 0.12 to 0.13
The separated water containing % by weight is first mixed with excess sludge and subjected to the aforementioned treatment. On the other hand, the solid content in excess sludge is approximately 0.5 to 0.
．． 6% by weight, but due to the above treatment, a centrifugal concentrator (8%
) The solid content in the sludge supplied with K is z1 to 2. ．． 2% by weight
The intermediate water from the conduit (9) has a solid content of 0.03 to 0.
．． 1% by weight, the amount is about 84-89% by weight of the total excess sludge.

The main component of surplus sludge is activated sludge, and it is known that this activated sludge causes a kind of adsorption, but on the other hand, the centrifugal compressor separated water contains dissolved and incorporated air l'6I.
Contains a lot of gold. The flotation concentration and sedimentation concentration of solid substances that occur in the separation tank (3), and the reduction in removal of solids in the separated water as seen from the separated water side, are due to the adsorption effect of this excess sludge and the coagulation and flotation effect due to air bubbles in the separated water. This can be said to be due to the synergistic effect of

For example, the +p reduced sludge from the centrifugal concentrator (8) has a solid content of 4-
'6-chi composition, stored in storage tank QO or directly,
Appropriate treatment will be taken.

As is clear from the description of the above embodiments, in the present invention, the volumetric load applied to the centrifugal concentrator (8) is equal to the difference between the amount of intermediate water drawn out from the conduit (9) and the amount of separated liquid from the conduit (2). Its main effect is to reduce In addition, the solids ultimately returned to the sewage treatment plant have been reduced to i-1 of the conventional method, and the recovered solids (thickened sludge, minus the solids discharged as separated liquid or intermediate water in the concentration process) Assuming that the excess sludge concentration is 0.6%, the power consumption of this system is as follows: conventional method 1871 (support) Vt
On the other hand, in Kempo, it is recognized that the energy saving effect is 45 陡■se't and Nasi, Dai III.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing the general configuration of a sewage treatment device. FIG. 2 is a sectional view showing an example of the structure of a centrifugal concentrator. Third
The figure is a process diagram showing the configuration of the present invention. A... Initial settling tank B... Aeration tank C... Final settling tank - E... Casing of centrifugal concentrator K... Rotating body of centrifugal concentrator M... Liquid level N in centrifugal concentrator ...Screw of centrifugal compressor rotor 3...-Separation tank 6...Storage tank 8...Centrifugal concentrator 10...Storage tank Applicant: Takuma Co., Ltd.

Claims (1)

[Claims] 1. Biodegrading wastewater in the presence of oxygen in an aeration tank,
Next, in a sewage treatment method that includes a step of separating the sludge by sedimentation in a (final) settling tank, returning one part to the aeration tank, and taking out the remaining part as surplus sludge and treating it with a centrifugal thickener: - The surplus sludge is Before being sent to the centrifugal thickener, it is mixed with separated water produced from the centrifugal compressor, and then stratified in a separation tank into a floating thickened sludge layer, a settled thickened sludge layer, and an intermediate clarification tank.
The intermediate clarified water is discharged out of the system, the floated thickened sludge layer and the sedimented thickened sludge layer are sent to the centrifugal thickener, and this separated water (same as the separated water) is mixed with excess sludge and centrifugally concentrated. A sludge thickening device that includes a structure for sending sludge into a sludge machine and discharging it to a centrifugally concentrated sludge layer 1.