JPH0751699A - Deodorizing method in sewage sludge treatment and device therefor - Google Patents

Abstract

PURPOSE:To remove malodor of concd. sludge generated in the treatment of sewage sludge at a low cost without causing environmental pollution by aerating the concd. sludge generated in the treatment of sewage sludge in the presence of humus to decompose the org. acid in the concd. sludge with microorganisms. CONSTITUTION:The concd. sludge from a thickener generated in the treatment of sewage sludge is introduced from a receiver pipe 11 into a first tank 10 into which air is blown from an aerator 13, aerated respectively in the tanks 10a, 10b and 10c in the presence of humus and then sent to a dehydrating stage 7 from a waste water pipe 12. The sludge is aerated with the air supplied from the aerator 13 successively in the tanks 10a, 10b and 10c in the increasing direction of an ORP value. Consequently, the org. acid in the concd. sludge generated by an anaerobic reaction in the preceding stage is decomposed by the microorganisms in the humus, that is, the pH is increased, and the generation of malodor is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewage sludge treatment, and more particularly to a deodorizing method and a deodorizing apparatus for concentrated sludge generated in a sewage sludge treating step until dehydration.

[0002]

2. Description of the Related Art Conventionally, in a sewage treatment plant, generally,
As shown in FIG. 3, after collecting dusts and the like on the screen 1, solid matters and sludge are first settled and separated in the settling tank 2, and then air is blown into the sewage in the aeration tank 3 to remove the sludge. After activating the microorganisms, sludge is separated and separated in the final settling tank 4, and then discharged to the outside of the system.
On the other hand, the sludge settled in the first settling tank 2 and the final settling tank 4 is concentrated in a thickening tank 5, and the thickened sludge is caked in a dehydrating step 7 through a storage tank 6 and then incinerated, for example. ing. By the way, since the concentrated sludge has a bad odor and the working environment is bad in the dehydration work place, the present situation is to add a metallic or oxidizing deodorant to the concentrated sludge to prevent the bad odor.

[0003]

However, since the above-mentioned deodorant is used in a large amount, not only the running cost becomes high, but also in the case of the metal-based deodorant, the concentrated sludge is dehydrated,
Even after incineration, heavy metals contained in deodorants may elute and accumulate in the natural world, causing new environmental deterioration.
Therefore, it is necessary to incinerate the dehydrated cake before it is dumped at the final disposal site, and to form and incinerate the incinerated ash to treat the heavy metal so as not to elute. Further, in the case of an oxidative deodorant, sulfuric acid is generated as a result of deodorization, so it is necessary to take measures against corrosion in pipes and equipment. Furthermore, since deodorization with a deodorant is due to a chemical reaction, it will not be effective unless the concentrated sludge and deodorant are uniformly mixed, so stirring is performed with a stirring device, but it is difficult to mix them uniformly. Is. Furthermore, in deodorization with a deodorant, it is necessary to add the deodorant at any time according to the flow of the concentrated sludge, and therefore, there is a problem that a deodorant receiving facility, a storage facility, and a quantitative supply facility are required. Have. As a result of various studies in order to solve the above problems, generally, concentrated sludge has a pH of 4.5 to 6.5 and an ORP value (oxidation-reduction potential) of −150 to 280 mV, and the main components of odor are hydrogen sulfide and methyl sulfide. It was clarified that sulfur compounds such as mercaptans can suppress the generation of odors by increasing the post-deodorization value than the pH value and ORP value of the concentrated sludge before the deodorization processing.

When the microorganisms existing in the sludge settle in the settling tank, the air is insufficient to generate an organic acid by an anaerobic reaction. On the other hand, when air is blown in, the microorganism has a function of decomposing the organic acid. And, many microorganisms that perform such biological action are present in inexpensive humus soil. Therefore, the present invention provides a deodorizing method and apparatus for treating sewage sludge, which utilizes the microorganisms in the humus to decompose the organic acid in the concentrated sludge to raise the pH of the sludge and suppress the generation of odor. The purpose is to do.

[0005]

In order to achieve the above object, the present invention is directed to a deodorizing method in the treatment of sewage sludge, wherein the concentrated sludge generated in the sewage sludge treatment step is aerated in the presence of humus soil. This is a device that decomposes organic acids in concentrated sludge by microorganisms, and its deodorizing device is equipped with a pipe for receiving concentrated sludge from the concentration tank in the sewage sludge treatment process, a pipe for discharging concentrated sludge to the dehydrator, and an aeration device. One tank is provided, the aeration device is provided in parallel with this first tank, and the second tank for feeding humus soil can circulate the concentrated sludge in the second tank with the first tank. It was communicated by piping.

[0006]

EXAMPLE An example of the present invention will be described below with reference to FIG. FIG. 1 shows a deodorizing device in the treatment of sewage sludge according to the present invention, and 10 has a receiving pipe 11 for receiving the concentrated sludge from the conventional concentration tank 5 and a discharge pipe 12 for discharging the dehydration process at one end. In the tank, in the figure,
The first tank 10 is composed of three tanks 10a, 10b and 10c, and each of the tanks 10a, 10b and 10c has a known aeration device 1
3 are installed. Further, 14 is a second tank for introducing humus, which is provided in parallel with the tanks 10b and 10c,
A part of the sludge from 0c is extracted, aerated for a predetermined time as described below, and then returned to the tank 10b. A publicly known aeration device 15 is also installed in the second tank 14.

Next, the deodorizing step in the deodorizing device having the above-mentioned structure will be described. The thickened sludge from the thickening tank 5 flows into the first tank 10 from the receiving pipe 11, air is blown from the aeration device 13, and the sludge aerated in the tanks 10a, 10b, 10c is discharged from the drain pipe 12 to the dehydration step 7. Sent. Then, the air supplied from the aeration device 13 in each of the tanks 10a, 10b, 10c is induced in a direction in which the aerobic, that is, the ORP value, increases more than the inflowing concentrated sludge, and as a result, by the anaerobic reaction in the previous step. The concentrated sludge, which tends to be acidic due to the generated organic acid, is decomposed by the microorganisms present inside the sludge, that is, the pH is increased and the generation of odor is suppressed.

By the way, according to the present invention, a part of the sludge in the tank 10c is returned to the second tank 14 and mixed with the humus that has been put in, and at the same time the air from the aeration device 15 is used for OR.
The P value is increased and the sludge is stirred for a predetermined time. As described above, since the humus contains a large number of microorganisms, the microorganisms are activated by the air, further decompose the organic acid in the concentrated sludge, and the pH becomes higher than that in the first tank 10.

As described above, when the organic acid is sufficiently decomposed in the second tank 14 for a predetermined time to decompose and the pH of the concentrated sludge increases, the sludge is returned to the first tank 10, in the embodiment, the tank 10b, While raising the pH of the first tank, it further activates the microorganisms therein to decompose organic acids and raises the pH value to suppress the generation of odors.
2 to the dehydration step 7.

[0010] Incidentally, the first tank 10, the storage amount is 1.2 m ³ in the second tank 14, with 0.4 m ^3, the inflow amount from the concentration tank is 4.8 m ³ / day, fed in each aeration tank When the amount of air was 200 liters / minute, the amount of sludge supplied to and returned from the second tank was 35 liters / time x 4 times / day, and the amount of humus input was 40 kg, the results were as shown in the table below. . Further, the results of changes over time are shown in FIG.

[0011]

[Table 1]

In the method of measuring the odor aging test shown in FIG. 2, the treated sludge and the sludge containing deorane L were sampled in a bucket made of synthetic resin, and the change with time of the odor was examined. The odor components were measured in the same manner as the odor analysis of hydrogen sulfide and methyl mercaptan.

[0013]

As is apparent from the above description, according to the present invention, microorganisms in inexpensive humus are utilized for deodorizing concentrated sludge in sewage sludge treatment without using a deodorant. Since the organic acid in the sludge is decomposed and the amount of oxygen dissolved is increased by deaeration to deodorize, there is no problem of pollution to the natural world due to elution of heavy metals, and thus the burning treatment of incinerated ash becomes unnecessary. In addition, since no corrosive substance is generated, it is not necessary to take measures against corrosion on the pipes and equipment, and the maintenance is easy. Furthermore, since the concentrated sludge and the microorganisms are agitated by aeration, they can be easily and uniformly mixed. Furthermore, since once the humus is added, the microorganisms self-reproduce, it is not necessary to replenish the humus for a long period of time, and it does not adversely affect the human body. , It is not necessary to provide facilities such as storage and input. Also, with respect to changes with time, the deodorizing effect of the present invention is longer than that of the deodorant.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a deodorizing device in sewage treatment of the present invention.

FIG. 2 is a graph showing changes in odor with time.

FIG. 3 is a process diagram of conventional sewage treatment.

[Explanation of symbols]

5 ... concentration tank, 10 ... first tank, 10a, 10b, 10c ...
Tanks 13, 15 ... Aeration device, 14 ... Second tank.

Claims (2)

[Claims] 1. A deodorizing method in sewage sludge treatment, which comprises aerating the concentrated sludge generated in the sewage sludge treatment step in the presence of humus to decompose organic acids in the concentrated sludge by microorganisms. 2. A first tank provided with a receiving pipe for the concentrated sludge from the thickening tank in the sewage sludge treatment process, a discharging pipe for the concentrated sludge to the dehydrator, and an aeration device is provided in parallel with the first tank.
In a sewage sludge treatment, characterized in that a second tank equipped with an aeration device and into which humus is charged is connected to the first tank by a pipe so that the concentrated sludge in the second tank can circulate. Deodorizing device.