JPS5917439Y2 - Sludge treatment equipment - Google Patents

Description

[Detailed description of the invention] The present invention relates to a sludge treatment device for anaerobically treating sludge such as sewage, and includes a digestion tank 1 for anaerobically digesting thickened sludge.
The present invention relates to a sludge treatment apparatus comprising: and a deaerator 2 disposed in a pre-process of a digestion tank 1 for deaerating concentrated sludge.

A conventional sludge treatment apparatus of this type was constructed as shown in FIG.

That is, in this system, sludge such as sewage is first forcibly concentrated using a pressure flotation method or centrifugation method, and the thickened sludge, which is a mixture of surplus sludge and initial settling sludge, is sent to the first digestion tank 21 and then to the second digestion tank. The sludge was sent to 22, where it was anaerobically digested by internal anaerobic bacteria to decompose the organic matter in the sludge, and the thus treated sludge was sent to deaeration step 23 and incineration step 24, where it was dehydrated and incinerated. It will then be thrown away.

However, in this case, the sludge becomes gelatin-like with a large amount of air bubbles trapped in it when it is forcibly concentrated in advance by pressure flotation method or centrifugation method, so this thickened sludge is transferred to the first digestion tank. When the thickened sludge is sent to the second digestion tank 21 and the second digestion tank 22, the air in the bubbles of the thickened sludge is also sent into the digestion tanks 21 and 22, which absolutely require anaerobic properties, resulting in a decrease in digestion efficiency and a decrease in the organic decomposition rate. will decrease.

When the organic matter decomposition rate decreases and the amount of organic matter remaining in the sludge increases as described above, it becomes difficult to separate the desorbed liquid produced by digestion of the sludge from the digested sludge, making processing in subsequent steps difficult.

By the way, in the conventional example, the decomposition rate of organic matter during digestion is only about 40%, and the organic matter content of digested sludge is 6.
The organic matter content of the digested sludge must be 55% or less, and the decomposition rate of organic matter in the sludge is 60%.
% or more.

As described above, in the conventional example, it is difficult to separate the desorbed liquid due to the low decomposition rate of organic substances, but in addition, in the conventional example, the organic substance is concentrated and becomes gelatinous. Since the sludge that has become sludge is directly sent to the digestion tanks 21 and 22, the thickened sludge that has become gelatinous is difficult to settle.
This also makes it even more difficult to separate the desorbed liquid from the digested sludge.

Therefore, in this conventional example, the digestion tanks are provided in two stages, the first digestion tank 21 and the second digestion tank 22, in an attempt to increase the efficiency of sludge digestion.
The second digestion tank 22 only had the function of separating the desorbed liquid, and no effect could be expected.

The present invention was developed in view of the above points, and is capable of preventing air from entering the digestion tank along with sludge, allowing efficient anaerobic digestion, and increasing the rate of decomposition of organic matter in sludge. It is an object of the present invention to provide a sludge treatment apparatus that can easily separate the desorbed liquid from digested sludge.

The present invention will be explained in detail below with reference to Examples.

FIG. 2 shows an embodiment of the sludge treatment apparatus of the present invention, in which a deaerator 2, a digestion tank 1, and a post-concentration tank 3 are arranged in the order of the sludge treatment process.

The deaerator 2 is formed by installing an agitator 6 that is rotationally driven by a prime mover 5 in a tank 4, and a thickening device (see Fig. (not shown).

The digestion tank 1 is disposed in the next step of the deaerator 2, and is connected to the deaerator 2 through a sludge input pipe 10 via a sludge extraction pump 8 and a sludge input pump 9.

Furthermore, the post-concentration tank 3 is disposed in the next process of the digestion tank 1 and is connected to the digestion tank 1 via a digested sludge drawing pipe 11. A sludge scraper 13 assembled with a rod-shaped body and rotationally driven by a prime mover 12 is installed inside the post-concentration tank 3.

Sludge is treated in the sludge treatment apparatus configured as described above in the following manner.

First, sludge such as sewage is forcibly concentrated using a pressure flotation method or a centrifugal separation method.

This forcedly concentrated sludge has a gelatinous consistency with many air bubbles.

This thickened sludge is introduced into the deaerator 2 through the raw sludge input pipe 7.

The sludge introduced into the deaerator 2 is passed through the rotating agitator 6.
The gelatinous thickened sludge is stirred for about 5 days, and the air bubbles in the gelatinous thickened sludge rise to remove air bubbles from the sludge.

Moreover, by installing the heater 14 in the deaerator 2 at this time, the sludge can be heated to about 60° C. and the efficiency of deaeration can be further improved.

If the sludge is heated to about 60°C in this way, deaeration will be completed in about one day.

In the above embodiment of the degassing device 2, the sludge is degassed by stirring, but there are other mechanical methods such as degassing by drawing a vacuum, or by introducing chemicals, etc. Chemical methods such as degassing may also be used.

The sludge thus deaerated is pulled out from the bottom of the tank 4 by a sludge extraction pump 8, and then transferred to the digestion tank 1 by a sludge input pump 9.
will be put into the

At this time, an input sludge warmer 15 is installed in the middle of the sludge input pipe 10 to heat the sludge, so that the heating of the sludge allows for efficient digestion in the digestion tank 1 in the next process. It's Nishide.

Sludge introduced into the digestion tank 1 from above is digested by anaerobic bacteria, and a portion of the digested sludge is passed through the return pipe 16 and the sludge input pipe 10.
The water is returned to the upper part of the digester 1 via the

In addition, the methane gas generated in the digestion tank 1 is collected and ejected into the digestion tank 1 again from the gas stirring nozzle 17, and the sludge in the digestion tank 1 is stirred by this jet of methane gas, resulting in a digestive action. This is so that it can be done efficiently.

In addition, although it is not normally used, if necessary, remove the desorbed liquid
The desorbed liquid can be taken out from 8.

Next, the digested sludge containing the desorbed liquid digested in the digestion tank 1 is pulled out from the bottom of the digestion tank 1 by the digested sludge withdrawal pipe 11.
It is then put into the concentration tank 3.

At this time, the sludge put into the digestion tank 1 is deaerated by the deaeration device 2, so air does not enter the digestion tank 1 together with the sludge, the digestion action by anaerobic bacteria is not inhibited, and the sludge in the sludge is A high organic matter decomposition rate of about 60% can be obtained, and it is possible to exist in a state where the organic matter content is 55% or less, which is generally considered to be easy to separate from the desorbed liquid. The digested sludge in 3 settles due to sedimentation and is easily separated from the desorbed liquid.

This separated digested sludge is turned into a tapered bottom by the rotating sludge scraper 13, and then scraped to the center of the bottom of the thickening tank 3, and drawn out by the concentrated digested sludge drawing pipe 19, and this concentrated digested sludge is further processed into the next step. It is dehydrated, incinerated, and then dumped.

Next, the digestion by the sludge treatment apparatus of the present invention and that by a conventional example will be compared based on a digestion experiment.

Table 1 shows the data of the digestion experiment according to the present invention, and Table 2 shows the data of the conventional digestion experiment.

From the results in Tables 1 and 2, in the conventional example, the organic decomposition rate was 41~
While it remains at around 45%, in this invention it is 60-63%.
% organic decomposition rate was obtained, which is confirmed to be significantly superior to the conventional example.

As mentioned above, the present invention is equipped with a deaeration device for deaerating the sludge in the pre-process of the digestion tank for anaerobically digesting the sludge.
It is possible to prevent air from entering the digestion tank together with the deaerated sludge, and there is no risk that the activity of anaerobic bacteria in the digestion tank will be inhibited by the action of air. The decomposition rate of organic matter can be improved.

As a result, the organic matter content in the digested sludge is reduced, and the desorbed liquid can be easily separated from the digested sludge.

Furthermore, since the digested sludge can be easily separated from the desorbed liquid in this way, the volume of the digested sludge can be reduced, and the sludge treatment in the subsequent process becomes easier.

[Brief explanation of the drawing]

FIG. 1 is a schematic process diagram of a conventional example, and FIG. 2 is a sectional view of an embodiment of the present invention. 1 is a digestion tank, and 2 is a deaerator.

Claims (1)

[Scope of utility model registration request] A sludge treatment device comprising: a digestion tank for anaerobically digesting thickened sludge; and a deaerator for deaerating the thickened sludge, which is disposed in a pre-process of the digestion tank.