JP2017154117A - Odor reducing device and odor reducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove hydrogen sulfide in short time in a treatment for removing hydrogen sulfide from a wastewater to be treated after an anaerobic treatment.SOLUTION: There is provided an odor reducing device for reducing odor of wastewater to be treated after an anaerobic treatment containing hydrogen sulfide, which has a microbubble supply device supplying microbubble to the wastewater to be treated. By the device, hydrogen sulfide is removed from the wastewater to be treated in short time and the amount of hydrogen sulfide gas which evaporates from the wastewater to be treated can be reduced.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an odor reducing apparatus and an odor reducing method for reducing the odor of wastewater to be treated after anaerobic treatment containing hydrogen sulfide.

Conventionally, as a wastewater treatment method for treating organic wastewater such as domestic wastewater, a method using anaerobic microorganisms is known. In anaerobic treatment using anaerobic microorganisms, sulfate ions and the like contained in organic wastewater are reduced to generate hydrogen sulfide (H ₂ S). Therefore, it is desired to remove hydrogen sulfide from the wastewater to be treated after anaerobic treatment.

  As a method of removing hydrogen sulfide from the treated wastewater after anaerobic treatment, the treated wastewater containing hydrogen sulfide is aerated in the presence of sulfur-oxidizing bacteria to activate the sulfur-oxidizing bacteria in the treated wastewater. A method for removing hydrogen sulfide is known (Patent Document 1).

Japanese Patent Laying-Open No. 2015-192949

  An object of the present invention is to remove hydrogen sulfide in a shorter time in the treatment of removing hydrogen sulfide from the wastewater to be treated after anaerobic treatment.

As a result of earnestly examining the above problems, the present inventor has found that hydrogen sulfide in the treated wastewater can be quickly removed by supplying microbubbles to the treated wastewater after anaerobic treatment containing hydrogen sulfide. Furthermore, the present invention has been completed by finding that the amount of hydrogen sulfide volatilized from the wastewater to be treated decreases.
That is, this invention is the following odor reduction apparatuses and odor reduction methods.

  The odor reducing device of the present invention for solving the above problems is an odor reducing device for reducing the odor of treated wastewater after anaerobic treatment containing hydrogen sulfide, and supplies microbubbles to the treated wastewater. A microbubble supply device is provided.

  According to the odor reducing apparatus of the present invention, by supplying microbubbles into the wastewater to be treated, the activity of sulfur-oxidizing bacteria in the wastewater to be treated is enhanced and at the same time physical oxidation is promoted. The hydrogen sulfide can be removed in a short time. Thereby, there exists an effect that the aerobic treatment tank for carrying out the aerobic treatment of to-be-processed wastewater can be reduced.

Moreover, the effect that the amount of hydrogen sulfide in the gas which volatilizes from the to-be-processed wastewater falls by supplying microbubbles to to-be-processed waste water was recognized.
When the wastewater to be treated is aerobically treated by aeration, hydrogen sulfide in the wastewater to be treated is volatilized into the gas together with air. Therefore, the exhaust gas in the aerobic treatment tank is treated with an odor component removing device such as activated carbon, and the exhaust gas The hydrogen sulfide in the inside is removed. According to the odor reducing device of the present invention, since the amount of hydrogen sulfide volatilized from the wastewater to be treated is reduced, it is possible to reduce the load of the odor component removing device, such as reducing the replacement frequency of activated carbon.

Furthermore, as one embodiment of the odor reducing device of the present invention, the microbubble supply device has a feature that microbubbles are generated using the wastewater to be treated.
By using a part of the wastewater to be treated as water supply for generating microbubbles, the amount of water supply from the outside of the aerobic treatment tank can be reduced, so the capacity of the aerobic treatment tank is further reduced. There is an effect.
In addition, since it is not necessary to perform large-scale piping work for supplying water from a water supply source outside the aerobic treatment tank to the microbubble supply device, it can be easily installed in the existing aerobic treatment tank. Also play.

  The odor reducing method of the present invention for solving the above-mentioned problem is an odor reducing method for reducing the odor of the wastewater to be treated after anaerobic treatment containing hydrogen sulfide, wherein microbubbles are added to the wastewater to be treated. It is characterized by comprising a supplying step.

According to the odor reducing method of the present invention, as in the odor reducing apparatus of the present invention, hydrogen sulfide in the wastewater to be treated can be removed in a short time, so that the treatment work of the wastewater to be treated can be reduced. it can.
Moreover, since the amount of hydrogen sulfide volatilized from the wastewater to be treated is reduced, it is possible to reduce work for removing odorous components in the exhaust gas, such as reducing the replacement frequency of activated carbon.

ADVANTAGE OF THE INVENTION According to this invention, in the process which removes hydrogen sulfide from the to-be-processed waste water after anaerobic treatment, hydrogen sulfide can be removed in a shorter time.
Furthermore, the effect of reducing the amount of hydrogen sulfide volatilized from the wastewater to be treated is also recognized.

It is a schematic explanatory drawing which shows the structure of the odor reduction apparatus of the 1st embodiment of this invention, and the anaerobic processing tank installed in the front | former stage. A graph showing the relationship between retention time of treated wastewater and removal rate of hydrogen sulfide (%) in treated wastewater for a comparative test using microbubbles having a bubble diameter of 100 μm or less and fine bubbles having a bubble diameter of about 1 mm. It is. Relationship between retention time of treated wastewater and amount of hydrogen sulfide generated per amount of treated water (μgH ₂ S / l) for comparative tests using microbubbles with a bubble diameter of 100 μm or less and fine bubbles with a bubble diameter of about 1 mm It is a graph which shows. It is a schematic explanatory drawing which shows the structure of the odor reduction apparatus of the 2nd embodiment of this invention, and the anaerobic processing tank installed in the front | former stage. It is a schematic explanatory drawing which shows the structure of the odor reduction apparatus of the 3rd embodiment of this invention, and the anaerobic processing tank installed in the front | former stage. It is a schematic explanatory drawing which shows the structure of the odor reduction apparatus of the 4th embodiment of this invention, and the anaerobic processing tank installed in the front | former stage.

  The odor reducing apparatus of the present invention is an apparatus for treating treated wastewater containing hydrogen sulfide after anaerobic treatment to reduce hydrogen sulfide in the treated wastewater, A microbubble supply device for supplying bubbles is provided.

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that this embodiment does not limit the present invention.
[First Embodiment]
FIG. 1 is a schematic explanatory view showing the structure of an odor reducing apparatus 1a according to the first embodiment of the present invention and an anaerobic treatment tank 10 installed in the preceding stage.

(Anaerobic treatment tank)
The anaerobic treatment tank 10 is a biological treatment tank for anaerobically treating the wastewater W2 such as organic wastewater with anaerobic microorganisms, and any anaerobic treatment may be performed as long as the treatment generates hydrogen sulfide. For example, the anaerobic processing apparatus comprised by the acid production tank and the methane fermentation tank etc. are mentioned. The waste water W2 is not particularly limited, and examples thereof include organic waste water from sewage treatment plants and food factories.

(Odor reduction device)
The odor reducing apparatus 1a according to the first embodiment of the present invention includes an aerobic treatment tank 2 for storing the treated wastewater W0 and a microbubble for supplying microbubbles to the treated wastewater W0 in the aerobic treatment tank 2. This is a configuration including a supply device 3. When the microbubbles are supplied to the wastewater W0 to be treated, hydrogen sulfide is removed by the action of sulfur-oxidizing bacteria contained in the wastewater to be treated W0.

  Further, an exhaust gas outflow part for exhausting the exhaust gas G is provided in the upper part of the aerobic treatment tank 2, and the exhaust gas outflow part is provided with an odor component removing device (not shown). The odor component removed from the wastewater W0 to be treated is removed by the odor component removal device, and the emission of a strange odor due to the exhaust gas G can be prevented.

  The odor component removing device may be any device as long as the odor component is removed, for example, a device that adsorbs the odor component to an adsorbent material such as activated carbon or an ion exchange membrane, or the odor component is burned at a high temperature. And a device for dissolving the odor component in an alkaline solution, a device for oxidizing the odor component with an oxidizing agent such as ozone, and the like. From the viewpoint of simplifying the apparatus, it is preferable to use an apparatus that adsorbs an odor component to an adsorbing material such as activated carbon.

  The microbubble supply device 3 is not particularly limited as long as it is configured to generate microbubbles and supply them to the aerobic treatment tank 2. A microbubble is a bubble of 100 μm or less, and activates sulfur-oxidizing bacteria in the treated wastewater W0. The gas that forms the microbubbles is not limited as long as it has an action of activating the sulfur-oxidizing bacteria. For example, in addition to forming microbubbles of air A as in the first embodiment, microbubbles such as oxygen Bubbles may be formed.

  In the present invention, the action of supplying microbubbles to the wastewater W0 to be treated is not only biological sulfur oxidation action by activating sulfur oxidizing bacteria, but also physical sulfur oxidation by the oxidizing power of microbubbles. The effect is also expected. Therefore, the type of gas used for the microbubbles may be selected in view of these effects. For example, the use of ozone microbubbles increases the physical sulfur oxidation action, but may reduce the action of sulfur-oxidizing bacteria due to its strong oxidizing power, so the balance between biological sulfur oxidation action and physical sulfur oxidation action is reduced. Considering it, it is preferable to use air or oxygen microbubbles.

The liquid used for the generation of the microbubbles is not particularly limited, and as in the first embodiment, the treated wastewater W0 is partially extracted and used for the generation of the microbubbles. A water supply source outside the odor reducing device such as water or industrial water may be used.
When using an external water supply source such as treated water W1 or tap water, it is necessary to increase the capacity of the aerobic treatment tank 2 by the amount of incoming water, and large installation work such as piping work is also required It is. Therefore, it is preferable to remove a part of the wastewater W0 to be treated and use it as a liquid for generating microbubbles.

  Microbubble generation methods include, for example, a gas-liquid shearing method in which a gas is engulfed in a liquid vortex and the vortex is broken, or a gas that is dissolved in a large amount of liquid under high pressure and re-bubbled by decompression. There is a pressure reduction method.

The microbubble supply device that generates microbubbles by the gas-liquid shearing method may have any configuration as long as it is a structure capable of entraining gas in a liquid vortex and breaking the vortex.
For example, a member that has a shape like a bell (hereinafter referred to as a “bell-like member”) is supplied with liquid from the side to form a vortex inside. In this bell-like member, the liquid rises while turning along the inner wall surface of the bell-like member and reverses upward. The inverted liquid descends as a vortex inside the rising swirl flow. The gas is taken in from the top of the bell-like member and is entrained in the descending vortex. Then, when the descending vortex is discharged from the bottom of the bell-like member, the vortex is blown off in the lateral direction, and the vortex is destroyed. At that time, a strong shearing force is applied to the gas, and microbubbles are generated.

In addition, a swirl plate, a propeller attached to a shaft, or the like can be installed inside the cylindrical member to form a vortex.
Moreover, as a method of destroying the eddy current, there are methods such as using an obstacle or ejecting into a relatively stopped bulk water.

  The microbubble generator by the pressure-depressurization method may have any configuration as long as it can be re-bubbled by depressurization after dissolving the gas in a liquid under high pressure, for example, a nozzle having a reduced-diameter discharge port, etc. Can be used. In this nozzle, a high-pressure liquid and gas are supplied before the discharge port to dissolve the gas in the liquid. Next, the pressure is reduced by discharging the liquid from the discharge port, and the gas dissolved in the liquid is re-bubbled to generate microbubbles.

  In the gas-liquid shearing method, microbubbles can be generated by self-supplying gas, so that the gas-liquid shearing method has an excellent effect in terms of power saving as compared with the pressure-reducing method that applies high pressure to the liquid and gas.

  The microbubble supply device 3 may be installed at any position as long as microbubbles can be supplied to the wastewater W0 to be treated. For example, you may install in the inside of the aerobic processing tank 2, and you may install in the piping which supplies the to-be-processed waste water W0 to the aerobic processing tank 2. FIG. From the viewpoint that it can be quickly supplied to the wastewater W0 to be treated, it is preferable to install the wastewater W0 to be treated.

The aerobic treatment tank 2 is configured to give a sufficient residence time for removing hydrogen sulfide from the wastewater to be treated W0, and its capacity is appropriately determined depending on the supply amount of the wastewater to be treated W0 and the ability to remove hydrogen sulfide. Is set.
The aerobic treatment tank does not need to be a tank, and may be a pipe as long as it can provide a sufficient residence time.

As another aspect of the aerobic treatment tank, air may be supplied together with the microbubble supply device 3 by an aeration device such as an air diffuser.
Moreover, it is good also as a structure containing the support | carrier which fixed the microorganisms. By providing the carrier, the concentration of sulfur-oxidizing bacteria increases, so that the treatment time can be further shortened.

  Next, a comparative test using microbubbles and fine bubbles of about 1 mm was performed to verify the effects of the microbubbles. The test results are shown in FIGS. This test is intended to clarify the difference in action and effect between microbubbles and fine bubbles of about 1 mm. This test is conducted with respect to conditions such as the removal rate of hydrogen sulfide, the amount of hydrogen sulfide generated per treated water volume, and the residence time. It is not intended to limit the scope of the invention.

FIG. 2 shows the retention time of treated wastewater and the removal rate of hydrogen sulfide (%) in treated wastewater for a comparative test using microbubbles having a bubble diameter of 100 μm or less and fine bubbles having a bubble diameter of about 1 mm. It is a graph which shows a relationship. The hydrogen sulfide removal rate (%) is a value indicating the ratio of hydrogen sulfide removed from the wastewater to be treated, and is obtained by the following equation (1).

Hydrogen sulfide removal ratio _{(%) = {- H 2} S concentration / raw wastewater W0 (H ₂ S concentration in the treated waste water W0 H ₂ S concentration in the treated water W1)} × 100 ... formula (1)

  When FIG. 2 is seen, when microbubble is used, it turns out that residence time is 30 minutes-2 hours, and all the hydrogen sulfide in to-be-processed waste water is removed. On the other hand, when fine bubbles were used, the hydrogen sulfide removal rate was about 60 to 80% in 3 hours. Therefore, when the microbubbles are supplied to the wastewater W0 to be treated, an excellent effect in removing hydrogen sulfide is recognized.

FIG. 3 shows a comparison test using microbubbles having a bubble diameter of 100 μm or less and fine bubbles having a bubble diameter of about 1 mm, and the retention time of wastewater to be treated and the amount of hydrogen sulfide generated per amount of treated water (μg H ₂ S / It is a graph which shows the relationship of l). The amount of hydrogen sulfide generated per amount of treated water (μg H ₂ S / l) is the amount of hydrogen sulfide (μg) volatilized from the treated wastewater W0 and discharged as exhaust gas G with respect to the amount of treated water W1 (1 liter). ) And is obtained by the following equation (2).

Amount of hydrogen sulfide generated per amount of treated water (μg H ₂ S / l) = amount of hydrogen sulfide recovered from exhaust gas G (μg) / amount of treated water (l) Equation (2)

  Referring to FIG. 3, when fine bubbles are used, the retention time is 3 hours (hydrogen sulfide removal rate is about 60 to 80% (see FIG. 2)), about 30 to 70 μg per liter of treated water. It can be seen that the hydrogen sulfide was volatilized. On the other hand, when microbubbles were used, only about 0 to 30 μg of hydrogen sulfide was volatilized per liter of treated water at a residence time of 30 minutes (hydrogen sulfide removal rate was about 60 to 100%). That is, the amount of hydrogen sulfide volatilized from the wastewater W0 to be treated until the hydrogen sulfide removal rate reached the identification level was about 30 to 70 μg when using fine bubbles, whereas microbubbles were used. In some cases, it can be seen that the reduction was about 0 to 30 μg.

  From this result, when microbubbles are used, activation of sulfur-oxidizing bacteria by microbubbles and physical sulfur oxidation by the oxidizing power of microbubbles are added, so the amount of sulfur removed in the wastewater to be treated is reduced. It is estimated that the amount of volatilization of hydrogen sulfide decreased and increased.

[Second Embodiment]
FIG. 4 is a schematic explanatory view showing the structure of the odor reducing apparatus 1b of the second embodiment of the present invention and the anaerobic treatment tank 10 installed in the preceding stage.
In the second embodiment, the treated water W1 is used as the liquid used for generating the microbubbles.

  Further, in the second embodiment, as a configuration for stably supplying the treated water W1 to the microbubble supply device 3, the treated water tank 4 for storing a part of the treated water W1 flowing out from the aerobic treatment tank 2 is provided. I have. Even when the flow rate of the treated water W1 is reduced by the treated water tank 4, the amount of microbubbles generated by the microbubble supply device 3 can be temporarily ensured.

[Third Embodiment]
FIG. 5 is a schematic explanatory diagram showing the structure of the odor reducing apparatus 1c according to the third embodiment of the present invention and the anaerobic treatment tank 10 installed in the preceding stage.
In the third embodiment, the microbubble supply device 3 is installed at a pipe for supplying the treated wastewater W0 to the aerobic treatment tank 2 as a position where the microbubble supply device 3 is installed.

  According to this configuration, since the microbubbles can be quickly supplied to the wastewater W0 to be treated, the capacity of the aerobic treatment tank 2 for securing the residence time can be reduced. Further, by supplying the microbubbles to the pipe, there is an effect that the microbubbles can be evenly distributed in the wastewater W0 to be treated without giving a stirring force or the like.

  Moreover, in the odor reduction apparatus 1c of the third embodiment, the aerobic treatment tank 2 includes the aeration apparatus 5.

[Fourth Embodiment]
FIG. 6 is a schematic explanatory view showing the structure of the odor reducing apparatus 1d according to the fourth embodiment of the present invention and the anaerobic treatment tank 10 installed in the preceding stage.
In the fourth embodiment, instead of the aerobic treatment tank 2, a long-distance pipe is provided. The microbubble supply device 3 is configured to supply microbubbles to a plurality of locations on a long-distance pipe, and uses treated water W1 as a liquid for generating microbubbles.

  By performing the aerobic treatment by the piping, odorous substances such as hydrogen sulfide can be removed while the treated water W1 is being transferred to the next step of the aerobic treatment.

  The use of the odor reducing apparatus and the odor reducing method of the present invention is used for the purpose of treating the treated wastewater W0 containing hydrogen sulfide that has been subjected to anaerobic treatment to reduce hydrogen sulfide in the treated wastewater W0. For example, when discharging treated wastewater W0 that has been anaerobically treated with anaerobic microorganisms from organic wastewater generated from sewage treatment plants, food factories, etc. After removing hydrogen sulfide by using the odor reducing apparatus of the present invention, it is discharged.

  Moreover, the odor reducing apparatus and the odor reducing method of the present invention can reduce the amount of hydrogen sulfide volatilized from the treated wastewater W0. Therefore, in the method for removing hydrogen sulfide from the wastewater W0 to be treated containing hydrogen sulfide after anaerobic treatment, it is used for the purpose of reducing hydrogen sulfide in the exhaust gas G.

DESCRIPTION OF SYMBOLS 1a, 1b, 1c, 1d ... Odor reduction apparatus, 2 ... Aerobic treatment tank, 3 ... Micro bubble supply apparatus, 4 ... Treatment water tank, 5 ... Aeration apparatus, 10 ... Anaerobic treatment tank, W0 ... Waste water to be treated, W1 ... Treated water, W2 ... drainage, A ... air, G ... exhaust, P ... pump, B ... blower

Claims (3)

An odor reducing device that reduces the odor of treated wastewater after anaerobic treatment containing hydrogen sulfide,
An odor reducing device comprising a microbubble supply device that supplies microbubbles to the wastewater to be treated.   The odor reducing apparatus according to claim 1, wherein the microbubble supply device generates microbubbles using the wastewater to be treated. An odor reduction method for reducing the odor of wastewater to be treated after anaerobic treatment containing hydrogen sulfide,
An odor reduction method comprising a step of supplying microbubbles to the wastewater to be treated.

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