JP2010058045A - Method and device for preventing offensive odor generation from storage tank for dewatered sludge cake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preventing offensive odor generation from a storage tank for dewatered sludge cake. <P>SOLUTION: The method for preventing offensive odor generation from a storage tank for dewatered sludge cake comprises a normal process where pressure in the storage tank 1 for dewatered sludge cake is reduced to prevent odors from leaking from the storage tank 1 for dewatered sludge cake to the outside, a pressure process where the inside of the storage tank 1 for dewatered sludge cake is pressurized to dewater dewatered sludge cakes 12 to extract surplus water 13, and a decompression process where pressure in the storage tank 1 for dewatered sludge cake is released to make the dewatered sludge cakes 12 aerobic. When the concentration of odorants in the storage tank 1 for dewatered sludge cake exceeds a first threshold value, the normal process is switched to the pressure process. It is preferable that a cycle consisting of the normal process, the pressure process, and the decompression process is repeated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for preventing generation of malodor from a sludge dewatering cake storage tank and a malodor generation preventing apparatus.

  As a method to prevent the generation of bad odor from the sludge dewatering cake storage tank, the method of removing bad odor or aeration treatment of sludge to supply deodorized air, that is, supplying air to sludge and dissolving odor substances in microorganisms such as aerobic activated sludge A method of metabolizing the sucrose and a method of sterilizing by holding excess sludge at a temperature of 80 ° C. or higher are performed. In addition, a method for preventing malodor by adding chemicals such as nitrite to sludge has been proposed.

JP 2003-290793 A JP 2002-18695 A

  However, the bad odor cannot be sufficiently suppressed by the sludge treatment method in which the sludge is aerated or the bacteria are sterilized at a high temperature. In addition, the processing method by adding chemicals such as nitrite causes an increase in processing cost, and in some cases, special equipment may be required, or chemicals and the like may cause harm to the human body.

  This invention makes it a subject to prevent generation | occurrence | production of the malodor from a sludge dewatering cake storage tank in view of the above problems.

The above-mentioned problem is a normal process for reducing the inside of the sludge dewatered cake storage tank and preventing the odor from leaking to the outside from the sludge dehydrated cake storage tank,
Pressurizing the sludge dewatering cake storage tank, dewatering the sludge dewatering cake and taking out excess water;
The problem is solved by a method for preventing the generation of malodor from the sludge dewatered cake storage tank, which comprises a depressurizing step of opening the inside of the sludge dewatered cake storage tank to the atmosphere and aerobizing the sludge dehydrated cake.

  In this method of preventing the generation of malodor from the sludge dewatering cake storage tank, the sludge dewatering cake can be aerobically prevented by simply depressurizing and pressurizing the inside of the storage tank according to the process, and chemicals are used. There is no need. In addition, since the sludge dewatering cake storage tank has a pressure-resistant structure and is provided with a decompression pump and a pressure pump, complicated equipment is not required, and the bad smell of the sludge dewatering cake can be prevented with simple equipment.

  In addition, pressurizing the sludge dewatering cake in the pressurization process and removing excess water can further reduce the moisture content of the sludge dewatering cake, reduce the volume of the sludge dewatering cake, and reduce the anaerobic content. It will also be suppressed.

  The malodor generation prevention method preferably includes a step of deodorizing the air in the sludge dewatered cake storage tank absorbed by the decompression pump in the normal step.

  Since the air in the sludge dewatering cake storage tank absorbed by the decompression pump is deodorized, it is possible to prevent malodor from leaking to the outside.

  Further, when the concentration of the odorous substance in the sludge dewatering cake storage tank exceeds the first threshold value, it is preferable to switch from the normal process to the pressure fixing.

  Since the process is switched based on the concentration of the odorous substance, the process is switched at an appropriate timing according to the situation of the sludge dewatering cake in the storage tank, and the generation of malodor from the storage tank can be efficiently prevented. .

  Moreover, in this malodor generation prevention method, the cycle which consists of a normal process, a pressurization process, and a pressure reduction process is good to be repeated.

  Since it is realized by repeating a cycle consisting of a normal process, a pressurizing process, and a decompression process, anaerobization of the sludge dewatering cake is regularly suppressed in the decompression process, thereby suppressing the anaerobization of the sludge dewatering cake. Odor generation is prevented. Moreover, it is possible to efficiently prevent the generation of bad odor with a small amount of energy.

  In addition, when this cycle is repeated, it is preferable that the pressurizing force in the pressurizing process increases stepwise from the initial set value.

  In order to make the sludge dehydrated cake aerobic in the decompression process, it is necessary to perform an explosive treatment and include air in the sludge dehydrated cake. The pressure is different. By increasing the pressure in the pressurizing step every time the cycle is repeated, the pressure in the storage tank can be increased, and the sludge dewatered cake can be explosively processed in the depressurizing step under an appropriate pressure.

  Furthermore, when this cycle is repeated, when the concentration of the odorous substance in the sludge dewatering cake storage tank becomes equal to or lower than the second threshold value in the normal process, the pressure in the pressurizing process may return to the initial set value.

  If the sludge dewatered cake is processed to the standard that does not cause odor, the sludge dehydrated cake is blasted under the optimum pressure in the decompression process. There is no need to increase. It also leads to labor saving of unnecessary energy.

In addition, this malodor generation prevention method, the sludge dewatering cake storage tank has a pressure-resistant structure,
A decompression device for decompressing the sludge dewatering cake storage tank;
A pressurizing device for pressurizing the sludge dewatered cake storage tank;
A sludge dewatering cake storage section for storing the sludge dewatering cake;
An excess water storage section for storing excess water dehydrated from the sludge dewatering cake;
The present invention is also realized by an apparatus for preventing the generation of malodor from the sludge dewatering cake storage tank, characterized in that it comprises an air release device for opening the inside of the sludge dewatering cake storage tank to the atmosphere.

  Since this invention is as above, generation | occurrence | production of the malodor from a sludge dewatering cake storage tank can be prevented.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  The malodor generation prevention apparatus 1 shown in FIG. 1 includes a sludge dewatering cake storage tank 2 for storing a sludge dewatering cake 12 and an excess water storage unit 3 for storing surplus water 13 dehydrated from the sludge dewatering cake 12. The storage part 2 and the surplus water storage part 3 are divided by a separator 4 that partitions each other, and the separator 4 is provided with holes 4a, 4a,. An excess water discharge port 10 for discharging the excess water 12 to the outside is connected to the excess water storage unit 3.

  Further, the sludge dewatering cake storage tank 1 has a decompression pump 5 for reducing the pressure in the storage tank and a deodorizing device 7 for storing gas drawn from the storage tank by the decompression pump and deodorizing odorous substances contained in the gas. The provided deodorizing tank 6 is connected. Further, a pressurizing pump 8 that pressurizes the pressure in the storage tank and an air release valve 9 that is connected to the storage tank and takes outside air into the storage tank and opens the inside of the storage tank to the atmosphere are provided. Further, in the sludge dewatering cake storage tank 1, a concentration measuring device 11 for measuring the concentration of odorous substances in the sludge dewatering cake storage tank 1 is provided.

  Odor generation from the sludge dewatering cake storage tank is prevented by the following procedure.

<Normal process>
In order to prevent odor from being generated from the sludge dewatered cake storage tank 12 stored in the sludge dehydrated cake storage tank 1 and leaking out of the sludge dehydrated cake storage tank 1, the decompression pump 5 is operated to operate the sludge dehydrated cake storage tank. The inside of 1 is maintained at a constant reduced pressure state. Further, the odor drawn out by the decompression pump 5 is sent to the deodorizing tank 6 and deodorized by the deodorizing device 7 provided in the deodorizing tank 6. The deodorization method should just select the deodorization method suitable for the odorous substance generate | occur | produced from the sludge dewatering cake 12, for example, the deodorization by activated carbon may be performed.

  In the sludge dewatering cake storage tank 1, a concentration measuring device 11 for measuring the concentration of the odorous substance in the storage tank is provided, and the odorous substance concentration in the sludge dewatering cake storage tank 1 is measured. If the odorous substance concentration in the sludge dewatering cake storage tank 1 is equal to or less than the set threshold (first threshold), the normal process is maintained as it is. However, when the odorous substance concentration in the sludge dewatering cake storage tank 1 exceeds a set threshold value (first threshold value), the process proceeds to the next pressurizing step. Here, the threshold value (first threshold value) may be set to an odorous substance concentration suitable for the odorous substance generated from the sludge dewatering cake 12, but for example, a reference value (for example, a odor substance prevention standard for odorous substances generated) In the case of hydrogen sulfide, it may be set based on 0.02 ppm). Further, switching from the normal process to the pressurization process may be performed manually or may be performed by automatic control. Since the switching from the normal process to the pressurizing process is performed based on the odor substance concentration in the sludge dewatered cake storage tank 1, the switching is performed at an optimal timing to prevent the generation of malodor in the sludge dehydrated cake storage tank. .

<Pressurization process>
When shifting from the normal process to the pressurization process, the decompression pump 5 is stopped and the pressurization pump 8 is operated. By making the inside of the sludge dewatering cake storage tank 1 into a pressurized state, pressure is applied to the sludge dewatering cake 12 stored in the sludge dewatering cake storage section 2 in the sludge dewatering cake storage tank 1, and further from the sludge dewatering cake 12. Dehydration is promoted. The surplus water 13 generated by the dewatering is transferred from the sludge dewatering storage tank 2 side to the surplus water storage tank 3 side through the holes 4 a, 4 a... Provided in the separator 4 separating the sludge degreasing storage tank 2 and the surplus water storage tank 3. It is captured. The surplus water 3 stored in the surplus water storage tank 3 is returned to the septic tank through the surplus water discharge port 10 connected to the surplus water storage section 3. By pressurizing the sludge dewatering cake in the pressurization process and taking out excess water, the moisture content of the sludge dewatering cake can be further reduced, the volume of the sludge dewatering cake can be reduced, and anaerobic control can be suppressed. Also become.

When the pressure in the sludge dewatering storage tank 1 reaches the set pressure due to pressurization in the pressurization process, the process proceeds to the next decompression process.
Here, the pressure in the sludge dewatering storage tank 1 for shifting from the pressurizing process to the depressurizing process is not always constant, and as will be described later, stepwise for each cycle consisting of a normal process, a pressurizing process, and a depressurizing process. It is controlled to increase the set pressure. This is because the pressure in the sludge degreasing storage tank suitable for the explosion treatment of the sludge dewatering cake 12 performed in the depressurization process varies depending on the components of the sludge dewatered cake and other conditions, and the pressure is increased every cycle. The cycle is repeated until the pressure is most suitable for the detonation cake explosion process. By increasing the pressure in the pressurizing step every time the cycle is repeated, the pressure in the storage tank can be increased, and the sludge dewatered cake can be explosively processed in the depressurizing step under an appropriate pressure. The increase amount of the pressurizing force per cycle may be increased by a constant value per cycle, or the increase amount of the pressurizing force may be increased or decreased as the number of cycles increases.

<Decompression process>
In the depressurization step, the pressurizing pump 8 is stopped, the atmosphere release valve 9 connected to the sludge dewatered cake storage tank 1 and taking air into the sludge dewatered cake storage tank 1 is opened, and the pressure in the sludge dewatered cake storage tank 1 is reduced. Set to atmospheric pressure. By opening the air release valve 9 all at once, the sludge dewatered cake storage tank 1 undergoes a severe pressure fluctuation from the pressurized state to the atmospheric pressure state. Air is taken into the interior and the sludge dewatered cake becomes aerobic. In the state where the sludge dewatering cake 12 is aerobic, the generation of odor from the sludge dewatering cake 12 is suppressed.

  After the explosion process is performed in the decompression process, the air release valve 9 is closed, the sludge defatted cake storage tank 1 is again shut off from the atmosphere, and the process proceeds to a normal process in which the decompression pump 5 is operated. Here, if the odorous substance concentration in the sludge dewatering cake storage tank 1 is equal to or less than the set threshold value (second threshold value), the pressure applied in the pressurizing process of the next cycle is returned to the initial set value. If it exceeds the threshold value (second threshold value), the pressurizing step is performed with a pressure higher than the pressure applied in the previous cycle. That is, as long as the odor substance concentration does not fall below the second threshold value in the normal process, the applied pressure in each pressurizing process for each cycle increases. The increase amount of the pressurizing force per cycle may be increased by a constant value per cycle, or the increase amount of the pressurizing force may be increased as the number of cycles increases, or may be decreased. Here, the threshold value (second threshold value) may be set to an odorous substance concentration suitable for the odorous substance generated from the sludge dewatering cake 12, but a threshold value (reference value) when shifting from the normal process to the pressurizing process ( A value lower than the first threshold) is set.

  In the normal process, when the odor is generated from the sludge dewatered cake 12 and the concentration of the odorous material in the sludge dewatered cake storage tank 1 exceeds the set threshold (first threshold), the process proceeds to the next pressurizing process. Then restart the cycle to prevent odors.

  In this method for preventing the generation of malodor from the sludge dewatering cake storage tank, the generation of malodor can be prevented by simply depressurizing and pressurizing the inside of the storage tank according to the process, and there is no need to use chemicals or the like. In addition, since the sludge dewatering cake storage tank has a pressure-resistant structure and is provided with a decompression pump and a pressure pump, complicated equipment is not required, and the bad smell of the sludge dewatering cake can be prevented with simple equipment.

  In addition, pressurizing the sludge dewatering cake in the pressurization process and removing excess water can further reduce the moisture content of the sludge dewatering cake, reduce the volume of the sludge dewatering cake, and reduce the anaerobic content. It will also be suppressed.

  Furthermore, since this malodor generation prevention method is realized by repeatedly performing a cycle consisting of a normal process, a pressurizing process, and a depressurizing process, the sludge dewatering cake is periodically aerobicized in the depressurizing process. In addition, the anaerobic generation of the sludge dewatered cake is suppressed, and the generation of malodor is prevented.

  Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention. For example, in the above embodiment, the case where the depressurization pump and the pressurization pump of the sludge dewatering cake storage tank are separated from each other, but may be an integrated type.

  Moreover, the transition of each process may be performed manually or by automatic control.

  In the above embodiment,

It is explanatory drawing which shows the outline of the apparatus which prevents the bad smell generation | occurrence | production of sludge dewatering cake. It is a flowchart which shows the process of the malodor generation prevention method of sludge dewatering cake.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sludge dewatering cake storage tank 2 ... Sludge dewatering cake storage part 3 ... Excess water storage part 5 ... Depressurization pump 6 ... Deodorizing tank 7 ... Deodorizing apparatus 8 ... Pressurization Pump 9 ... Air release valve 11 ... Concentration measuring device 12 ... Sludge dewatering cake 13 ... Excess water

Claims (7)

Normal process to depressurize the sludge dewatering cake storage tank and prevent odor from leaking out from the sludge dewatering cake storage tank,
Pressurizing the sludge dewatering cake storage tank, dewatering the sludge dewatering cake and taking out excess water;
A depressurization process for opening the sludge dewatering cake storage tank to the atmosphere and aerobizing the sludge dewatering cake;
A method for preventing the generation of malodor from a sludge dewatering cake storage tank.   The method for preventing the generation of malodor from the sludge dewatering cake storage tank according to claim 1, comprising a step of deodorizing air in the sludge dewatering cake storage tank absorbed by the decompression pump in the normal process.   The method for preventing the generation of malodor from the sludge dewatering cake storage tank according to claim 1 or 2, wherein when the concentration of odorous substance in the sludge dewatering cake storage tank exceeds a first threshold value, the normal process is switched to the pressurization process.   The malodor generation prevention method according to claim 1, wherein a cycle including the normal process, the pressurizing process, and the depressurizing process is repeated.   The malodor generation prevention method according to claim 4, wherein the pressurizing force in the pressurizing step increases stepwise from an initial set value every time the cycle is repeated.   The malodor generation prevention method according to claim 5, wherein when the concentration of the odorous substance in the sludge dewatering cake storage tank becomes equal to or lower than the second threshold value in the normal process, the pressure applied in the pressurizing process returns to the initial set value. The sludge dewatering cake storage tank has a pressure-resistant structure,
A decompression device for decompressing the sludge dewatering cake storage tank;
A pressurizing device for pressurizing the sludge dewatered cake storage tank;
A sludge dewatering cake storage section for storing the sludge dewatering cake;
An excess water storage section for storing excess water dehydrated from the sludge dewatering cake;
An air release device for opening the sludge dewatered cake storage tank to the atmosphere;
An apparatus for preventing the generation of malodor from a sludge dewatering cake storage tank.

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