JP2008238118A - Pretreatment unit of organism deodorization plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a fart which contains a sulfuric compound such as hydrogen sulfide and organic matter such as ethanol as an odorous component from blocking a packed bed of a pretreatment system provided on the former stage of an organism deodorization tower. <P>SOLUTION: A sprinkling means 21 is provided in a gas-liquid contact tower 11 of a pretreatment unit 10 provided before the organism deodorization tower 60. An acidic liquid is sprinkled from the sprinkling means 21 to the packed bed 13 provided on an absorption chamber 12 inside the gas-liquid contact tower 11. The fart introduced from a gas introduction pipe 32 inside the gas-liquid contact tower 11 and containing the sulfuric compound such as hydrogen sulfide and the organic matter such as ethanol as the odorous component contacts the acidic liquid in the process of coming up the absorption chamber 12. The acidic liquid absorbs the odorous component in the fart and further, an increase of activated sludge in the packed bed 13 is suppressed because of the acidity. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a deodorizing equipment for odor gas containing a sulfur compound such as hydrogen sulfide and an organic substance such as alcohol, organic acid, and aldehyde. In particular, the present invention relates to a pretreatment unit provided in front of a biological deodorization tower that biologically deodorizes odorous gas.

  Adsorption methods, chemical solution cleaning methods, biological deodorization methods, and the like are known as odor gas treatment techniques. As a deodorization facility by the biological deodorization method, there is a facility including a biological deodorization tower in which microorganisms that decompose odor components are held. The biological deodorization tower is filled with a filler for holding microorganisms, and odorous gas is usually introduced into the tower from the bottom of the tower. The odor gas introduced into the tower rises in the tower and passes through the packed bed formed in the tower, so that the odor components contained in the odor gas are decomposed by the action of microorganisms held in the filler, The processing gas from which the odor component has been removed is taken out from the upper part of the tower.

  Examples of odor components contained in the odor gas include sulfur compounds, nitrogen compounds, and organic substances. Specifically, examples of the sulfur compound include hydrogen sulfide, methyl mercaptan, and methyl sulfide. Examples of the nitrogen compound include ammonia, examples of the organic substance include aliphatic oxygen compounds such as methanol, ethanol, acetaldehyde, and acetic acid.

  The said odor component is decomposed | disassembled by different microorganisms according to the kind. For example, sulfur compounds are decomposed by sulfur oxidizing bacteria, hydrogen sulfide oxidizing bacteria, and the like, and nitrogen compounds are decomposed by ammonia oxidizing bacteria, nitrite oxidizing bacteria, and the like. On the other hand, organic matter is decomposed by a group of microorganisms collectively called “activated sludge”. Activated sludge is used when biologically treating organic wastewater, and has a higher growth rate than microorganisms that decompose sulfur compounds and nitrogen compounds. For this reason, when the odor gas containing organic substance is introduced into the biological deodorization tower, activated sludge grows in the tower and the packed bed is blocked.

  When the packed bed in the biological deodorization tower is blocked, the pressure loss increases and the movement of the gas moving through the tower is hindered, and stable treatment cannot be performed. In order to solve such a problem, a treatment method is adopted in which a pretreatment unit is provided before the biological deodorization tower, and an odor gas from which organic odor components are removed is introduced into the biological deodorization tower. As a pretreatment unit, like a biological deodorization tower, it has a gas-liquid contact tower provided with a sprinkling means for sprinkling water from the upper part of the packed bed while forming a packed bed by putting a packing material inside a sealable tower Is commonly used.

Since the gas-liquid contact tower is filled with a packed bed and sprinkled, the packed bed is blocked by the growth of activated sludge in the same manner as the biological deodorization tower. As a technique for solving this problem, there is a preprocessing unit disclosed in Patent Document 1. In the pretreatment unit disclosed in Patent Document 1, a cleaning device for cleaning the filler in the gas-liquid contact tower with high-pressure water after providing watering means inside the introduction pipe for introducing odor gas into the gas-liquid contact tower Have
JP-A-10-33934

  In the pretreatment unit disclosed in Patent Document 1, the amount of water used increases because water is sprayed not only in the gas-liquid contact tower but also in the introduction pipe. In addition, since the amount of organic matter removed by watering the introduction pipe is not large, the gas introduced into the gas-liquid contact tower still contains a lot of organic matter. For this reason, in the gas-liquid contact tower, activated sludge grows using organic substances in the gas as a substrate. Therefore, in the pretreatment unit of Patent Document 1, a cleaning device that supplies high-pressure water to clean the packed bed is provided inside the gas-liquid contact tower.

  However, providing the watering means in the introduction pipe and providing the cleaning device in the gas-liquid contact tower complicate the device configuration. Furthermore, in order to be able to clean the inside of the packed bed, it is necessary to make the packed bed coarse, and the thickness of the packed bed must be reduced. Making the mesh of the packed bed coarse or reducing the thickness of the packed layer reduces the area where the gas contacts the filler and reduces the effect of removing odor components due to the gas passing through the packed layer. Furthermore, since it is necessary to use a high-pressure pump in order to supply high-pressure water to the packed bed, a power cost for moving the high-pressure pump is required.

  As described above, the technique described in Patent Document 1 cannot sufficiently prevent clogging of the packed bed of the gas-liquid contact tower due to the organic substance contained in the odor gas. Furthermore, the technique described in Patent Document 1 also has problems such as a complicated apparatus, an increase in power cost, and a reduction in odor component removal effect. In contrast to such conventional techniques, the present invention aims to solve the above problems by effectively suppressing the growth of activated sludge in the packed bed of the gas-liquid contact tower.

  In the present invention, the inside of the gas-liquid contact tower in which the packed bed is formed is sprinkled with an acidic liquid to make the packed bed an environment unsuitable for growing activated sludge, thereby suppressing the growth of activated sludge, Solve the problem. More specifically, the present invention provides the following.

(1) A gas-liquid contact tower having an absorption chamber into which an odor gas containing a sulfur compound and an organic substance is introduced, which is a pretreatment unit disposed in a front stage of a biological deodorization tower in which sulfur-oxidizing bacteria are held; A pretreatment unit for a biological deodorization plant, comprising: watering means for spraying an acidic liquid into an absorption chamber.
(2) An acid solution tank holding the acid solution, a return liquid path connected to the gas-liquid contact tower and the acid solution tank, and an acid solution supply connected to the acid solution tank and the watering means A circulating means for removing the acidic liquid sprinkled in the absorption chamber from the gas-liquid contact tower and circulating it to the sprinkling means, and a drain containing sulfuric acid discharged from the biological deodorization tower. A pretreatment unit for a biological deodorization plant according to (1), further comprising:
(3) A cleaning liquid path connected to the acid liquid tank and the gas-liquid contact tower, a liquid feeding means for supplying the liquid in the acid liquid tank to the gas-liquid contact tower via the cleaning liquid path, and the gas A cleaning device having an aeration means for aerating the inside of the liquid contact tower, a gas introduction pipe into which the odor gas is introduced and connected to the gas-liquid contact tower, and a branch from the gas introduction pipe and connected to the biological deodorization tower The pretreatment unit for a biological deodorization plant according to (2), further comprising: a bypass pipe; and a gas flow path switching unit that allows the odorous gas to flow through either the gas introduction pipe or the bypass pipe.
(4) An acid solution tank holding the acid solution, a return liquid path connected to the gas-liquid contact tower and the acid solution tank, and an acid solution supply connected to the acid solution tank and the watering means A circulating means for removing the acidic liquid sprinkled in the absorption chamber from the gas-liquid contact tower and circulating it to the sprinkling means, and discharging the acidic liquid sprinkled in the absorption chamber. The pretreatment unit for a biological deodorization plant according to any one of (1) to (3), further including a drain pipe that maintains the organic substance concentration of the liquid at 20,000 mg / L or less.
(5) A method for biological deodorization of odor gas containing a sulfur compound and an organic substance, wherein the odor gas is introduced into a gas-liquid contact tower, the acidic liquid is sprinkled to absorb the organic substance in the acidic liquid, A method for biological deodorization of odorous gas introduced into a biological deodorization tower in which sulfur-oxidizing bacteria are retained.

  The pretreatment unit according to the present invention is provided in front of a biological deodorization tower for removing odor components mainly composed of hydrogen sulfide. The odor gas introduced into the pretreatment unit includes a sulfur compound containing at least hydrogen sulfide and an organic substance decomposed by an aerobic microorganism group collectively referred to as “activated sludge”, in addition to these nitrogen compounds such as ammonia. Etc. may be included. The odor gas suitably treated according to the present invention is a gas containing about 5 to 2,000 ppm by volume of sulfur compounds and about 10 to 500 ppm by volume of organic substances as odor components. Specifically, gas generated from organic sludge and industrial waste, or gas generated when methane fermentation of these is mentioned.

  In the present specification, the “organic matter” means an odor component contained in malodor generated when waste is generated or treated. In particular, aliphatic oxygen compounds are easily assimilated into activated sludge, and odorous gas containing 10 ppm by volume or more of aliphatic oxygen compounds as organic substances is a suitable treatment target of the present invention. Examples of the aliphatic oxygen compound include alcohols such as ethanol and methanol, aldehydes, and organic acids such as acetic acid and propionic acid.

  The pretreatment unit is connected to a biological deodorization tower that holds at least sulfur-oxidizing bacteria, and is configured to introduce gas (pretreatment gas) extracted from the pretreatment unit into the biological deodorization tower. Water is also sprayed in the biological deodorization tower, and the sulfur compound is absorbed into the sprinkled liquid and is oxidized by a group of microorganisms including sulfur-oxidizing bacteria held in the biological deodorization tower.

  In particular, when the gas introduced into the biological deodorization tower contains 1.0 ppm by volume or more of hydrogen sulfide, sulfate ions are generated by oxidation of hydrogen sulfide by sulfur-oxidizing bacteria. For this reason, the waste water (drain) sprinkled in the biological deodorization tower and discharged from the biological deodorization tower contains about 100 to 10,000 mg / L sulfuric acid and has a pH of about 1 to 3. In such a case, as described in (2), the drain containing sulfuric acid may be used for the preparation of acidic water that sprinkles water in the gas-liquid contact tower of the pretreatment unit.

  In this invention, the proliferation of activated sludge is suppressed by making the inside of a gas-liquid contact tower into an environment unsuitable for the proliferation of activated sludge. However, the growth rate of microorganisms (activated sludge) in the gas-liquid contact tower is faster than the growth rate of microorganisms (such as sulfur-oxidizing bacteria) in the biological deodorization tower. Therefore, when configured so that the packed bed in the gas-liquid contact tower can be cleaned as described in (3) and odor gas can be directly introduced into the biological deodorization tower during the cleaning of the gas-liquid contact tower. Good. Thereby, the stop of the whole biological deodorization plant accompanying obstruction | occlusion of the packed bed of a gas-liquid contact tower and washing | cleaning of a gas-liquid contact tower can be avoided.

  If the acid solution is circulated between the gas-liquid contact tower and the acid solution tank using the acid circulation means, the amount of replenishment water and acid used for preparation of the acid solution can be reduced. However, since the acidic liquid absorbs the odor gas containing organic matter in the gas-liquid contact tower and contains the organic matter, the acidic liquid containing organic matter discharged from the gas-liquid contact tower as appropriate as described in (4) It is advisable to provide a drain pipe that discharges water. The connection position of the drain pipe is not limited, and may be connected to a gas-liquid contact tower, or may be connected to a member (for example, a return liquid path or an acid solution tank) constituting a circulation means.

  In this invention, the activity of activated sludge is weakened and the proliferation is suppressed by sprinkling an acidic liquid in the inside of the pre-processing unit into which the odor gas containing an organic substance is introduced. For this reason, according to this invention, without increasing the watering means provided in a pre-processing unit, the proliferation of activated sludge can be suppressed effectively and obstruction | occlusion of a packed bed can be prevented.

  Next, the present invention will be described in detail with reference to the drawings. Hereinafter, the same members are denoted by the same reference numerals, and description thereof is omitted or simplified. FIG. 1 is a schematic diagram of a biological deodorizing plant 1 according to a first embodiment of the present invention. The biological deodorization plant 1 includes a biological deodorization tower 60 and a pretreatment unit 10 </ b> A provided in the front stage of the biological deodorization tower 60.

  The pretreatment unit 10A is mainly configured of a gas-liquid contact tower 11 having an internal space and a sealable tower. The water spray means 21, the acid liquid tank 22, and the acid liquid are mixed with the gas-liquid contact tower 11 and the acid liquid. Circulating means 40 for circulating between the liquid tank 22 is included. In FIG. 1, the gas-liquid contact tower 11 and the biological deodorization tower 60 are represented by a schematic sectional view in the vertical direction in order to show the internal configuration.

  The interior of the gas-liquid contact tower 11 is a space in which a packed bed 13 formed by filling a filler 13S is formed. An outlet end of the gas introduction pipe 32 is connected to the lower part of the gas-liquid contact tower 11, and an inlet end of the gas feed pipe 33 is connected to the upper part. The space from the gas introduction pipe 32 to the gas feed pipe 33 in the gas-liquid contact tower 11 constitutes the absorption chamber 12. Odor gas is introduced into the pipe from the inlet end of the gas introduction pipe 32, enters the gas-liquid contact tower 11, rises in the absorption chamber 12, and is taken out from the gas feed pipe 33.

  The water sprinkling means 21 is disposed above the absorption chamber 12, specifically above the upper end of the packed bed 13. The water sprinkling means 21 is composed of a spray nozzle, and is connected to the outlet end of the acid solution supply path 42 that supplies the liquid for water sprinkling. The watering means 21 is not limited to a spray nozzle, and may be a watering plate or a shower nozzle.

  The inlet end of the acid supply path 42 is connected to the acid solution tank 22. The acid solution tank 22 is also connected to outlet ends of an acid replenishment passage 43 and a replenishment water passage 44 for supplying acid. An acid is supplied from the acid supply path 43 and mixed with water supplied from the supply water path 44 to prepare an acid solution. The acidic liquid preferably has a pH of 4 or less, particularly preferably about pH 2 or more and 3 or less.

  Although the kind of acid used for preparing the acidic liquid is not particularly limited, it is preferable to use a mineral acid because the organic acid assimilated to the activated sludge causes the activated sludge to grow. Specifically, hydrochloric acid, sulfuric acid, citric acid, or the like may be used. In addition, as the water supplied from the replenishing water channel 44, it is preferable to use water having a low organic matter concentration (for example, about equal to or lower than tap water). . However, it is not preferable that activated sludge is contained in the acidic liquid. Therefore, when the drain is regenerated by treating with activated sludge in an aeration tank to obtain replenishment water, treated water obtained by separating the activated sludge by solid-liquid separation of the water flowing out of the aeration tank and containing the activated sludge may be used.

  The acidic liquid is sprinkled from the sprinkling means 21 to the upper end of the packed bed 13. The acidic liquid absorbs the odor component by being countercurrently contacted with the odor gas rising up the packed bed 13 while descending the packed bed 13 and accumulates in the lower part of the gas-liquid contact tower 11. In the process of passing through the packed bed 13, the acidic liquid absorbs organic substances such as ethanol, methanol, and organic acids. In the acidic liquid, the activity of activated sludge having an optimum pH of about 6 to 7 is inhibited. For this reason, by sprinkling the acidic liquid from the water sprinkling means 21, it is possible to suppress the growth of activated sludge in the packed bed 13 of the gas-liquid contact tower 11.

  The gas-liquid contact tower 11 is connected to the inlet end of the return liquid passage 41 and the upstream drain pipe 47 at a position lower than the position where the gas introduction pipe 32 is connected. An acidic liquid (hereinafter, absorbed acid liquid) that has absorbed the odor component and accumulated in the lower part of the gas-liquid contact tower 11 is taken out from the return liquid passage 41. The outlet end of the return liquid path 41 is connected to the acid liquid tank 22, and the absorbed acid liquid is taken out from the gas-liquid contact tower 11 through the return liquid path 41 and returned to the acid liquid tank 22. If the organic liquid concentration in the acidic liquid is high, the effect of suppressing the growth of activated sludge is reduced. Therefore, the absorbed acid liquid is appropriately adjusted so that the organic liquid concentration in the acidic liquid is within about 1,000 to 20,000 mg / L. To discharge from.

The acid solution tank 22 is supplied with replenishing water from the replenishing water channel 44 as needed, and acid is added from the acid replenishing channel 43 so that the pH becomes 4 or less, preferably pH 2-3. In the middle of the acid liquid supply path 42 circulation pump P ₁ for circulation are provided. Thereby, the circulation means 40 including the return liquid path 41, the acid liquid supply path 42, and the circulation pump P ₁ is configured. The circulation supplied to is performed.

  The odor gas introduced into the gas-liquid contact tower 11 passes through the packed bed 13 so that most of the organic matter (for example, about 70 to 99%) is absorbed by the acidic liquid, and a part of the sulfur compound (for example, 50 to 90). %) Is also absorbed. Therefore, the odor component contained in the odor gas (hereinafter referred to as pretreatment gas) taken out from the gas-liquid contact tower 11 is mainly a sulfur compound. The pretreatment gas is taken out from the gas feed pipe 33 connected to the upper part of the gas-liquid contact tower 11. The outlet end of the gas feed pipe 33 is connected to the lower part of the biological deodorization tower 60.

  The biological deodorization tower 60 has the same configuration as the gas-liquid contact tower 11 and is a sealable tower having a reaction chamber 62 in which a packed bed 63 filled with a filler 13S is formed. The pretreatment gas introduced into the biological deodorization tower 60 has a small amount of components that propagate activated sludge, that is, organic matter (for example, 10 ppm by volume or less). For this reason, the packed bed 63 holds microorganisms that decompose sulfur compounds such as sulfur-oxidizing bacteria. Specifically, the packed bed 63 includes, for example, a microorganism that oxidizes hydrogen sulfide to generate sulfuric acid in the lower part, a microorganism that decomposes methyl mercaptan in the upper part, and decomposes methyl sulfide and methyl disulfide between the upper part and the lower part. It is configured to hold microorganisms.

  In the biological deodorization tower 60, water sprinkling means 64 is provided above the upper end of the packed bed 63. The watering means 64 is connected to the replenishing water channel 44, and the water supplied from the watering means 64 is sprinkled on the upper end of the packed bed 63. The sprayed water contacts the pretreatment gas that descends the packed bed 63 and ascends the packed bed 63. The packed bed 63 holds microorganisms that decompose sulfur compounds, and the sulfur compounds absorbed in water are decomposed into microorganisms. As a result, the sulfur compound is removed from the pretreatment gas, and other odor components contained in the pretreatment gas, such as organic substances and nitrogen compounds that have not been removed by the pretreatment unit 10A, are also removed. Therefore, the processing gas from which the odor component is removed is taken out from the processing gas pipe 34 attached to the upper part of the biological deodorization tower 60.

  Although the same thing may be used as the filler 13S with which the gas-liquid contact tower 11 and the biological deodorizing tower 60 are filled, another thing may be used. In the case of using a different material, a material that is difficult to retain microorganisms (for example, a hydrophobic plastic cylinder) is used as a filler to be filled in the gas-liquid contact tower 11, while a filler to be filled in the biological deodorization tower 60 is used. It is preferable to use a product having excellent ability to retain microorganisms (for example, peat, synthetic fiber molded product). In particular, a synthetic fiber molded product can be suitably used from the viewpoint of pressure tightness. The filler is filled so as to have a height of 50 to 100% of the absorption chamber (reaction chamber), but only a part of the filler 13S filled in the packed layers 13 and 63 is shown in the figure.

  The water (drain) accumulated in the lower part of the biological deodorization tower 60 after descending the packed bed 63 is generated in the process of microbial decomposition or components that are not microbially decomposed among the odor components absorbed by the contact with the pretreatment gas. Decomposition byproducts. A rear drain pipe 48 is connected to the biological deodorization tower 60 at a position lower than the position where the gas feed pipe 33 is connected, and the drain is discharged. The drain taken out from the rear-stage drain pipe 48 is led to an aeration tank (not shown) in which activated sludge is held together with the absorbing acid solution appropriately discharged from the front-stage drain pipe 47 and processed.

  The biological deodorization tower 60 may be provided with a circulating means for circulating the drain to the sprinkling means 64. When the pretreatment gas contains about 1 ppm by volume or more of hydrogen sulfide, the drain contains about 100 to 10,000 mg / L or more of sulfuric acid as a decomposition by-product and exhibits a pH of about 1 to 3. For this reason, the drain can be sent to the pretreatment unit 10A and used as an acidic liquid.

  FIG. 2 is a schematic diagram of the biological deodorizing plant 2 according to the second embodiment of the present invention. The biological deodorization plant 2 is different from the biological deodorization plant 1 according to the first embodiment of the first embodiment in that a drain supply pipe (drain supply path) 45 branched from the downstream drain pipe 48 is connected to the acid solution tank 22. Different. In the biological deodorizing plant 2, a pretreatment gas containing about 1 to 100 ppm by volume of hydrogen sulfide is introduced into the biological deodorizing tower 60 to obtain a drain containing sulfuric acid and having a pH of about 1 to 3. To supply.

  Although the acid solution is prepared in the acid solution tank 22, since the drain containing sulfuric acid is used for the preparation of the acid solution, the amount of water and acid supplied to the acid solution tank 22 can be reduced. Therefore, it is possible to reduce the amount of waste water generated from the front drain pipe 47 and the rear drain pipe 48 for processing.

  The drain contains the sulfur-oxidizing bacteria retained in the packed bed 63 of the biological deodorization tower 60, and a drain-containing acidic liquid (an acidic liquid containing a drain from the biological deodorization tower 60) sprayed into the gas-liquid contact tower 11 is provided. Contains sulfur-oxidizing bacteria. For this reason, decomposition of the sulfur compound proceeds in the gas-liquid contact tower 11 by the sulfur-oxidizing bacteria supplied into the gas-liquid contact tower 11 as the drain-containing acidic liquid is sprinkled. Therefore, the sulfur compound content of the pretreatment gas taken out from the pretreatment unit 10B can be further reduced, the load on the biological deodorization tower 60 can be reduced, and the biological deodorization tower 60 can be downsized.

FIG. 3 is a schematic diagram of the biological deodorizing plant 3 according to the third embodiment of the present invention. The biological deodorization plant 3 differs from the biological deodorization plant 2 of FIG. 2 in that the pretreatment unit 10C is provided with a cleaning device 24 and a gas flow path switching means. The cleaning device 24 includes a cleaning liquid path 24 connected to the acid solution tank 22 and the gas-liquid contact tower, a cleaning pump P ₂ as a liquid feeding means, and an aeration means 26. The cleaning liquid path 24 is connected to the lower part of the gas-liquid contact tower 11, specifically below the connection position of the gas introduction pipe 32, and a cleaning pump P ₂ is provided in the middle of the cleaning liquid path 24. The cleaning liquid is taken out from the acid solution tank 22 by the action of the cleaning pump P ₂ and supplied to the lower part of the gas-liquid contact tower 11.

  A diffuser nozzle 27 is provided at the lower part of the gas-liquid contact tower 11. The air diffusion nozzle 27 is connected to the blower B. In the biological deodorization plant 3 of the third embodiment, when the packed bed 13 of the pretreatment unit 10C is closed and the pressure loss increases, the liquid in the acid bath 22 is supplied to the gas-liquid contact tower 11 as a cleaning liquid. Then, the filling layer 13 is immersed. After the filling layer 13 is immersed in the liquid, air is blown from the blower B, whereby bubbles are generated from the aeration nozzle 27 and the filling layer 13 is aerated and washed. In addition, the immersion of the filling layer 13 is performed in order to enhance the aeration cleaning effect of the filling layer 13, and the replenishment water 44 may be supplied and immersed.

  In the biological deodorization plant 3, since the packed bed 13 is immersed in the liquid and aerated, the sludge adhering to the packed bed 13 can be easily peeled as compared with the case where the packed bed 13 is not immersed in the liquid. For this reason, it is not necessary to spray the cleaning liquid onto the filling layer 13 at a high pressure, and it is not always necessary to provide a high-pressure pump for feeding the cleaning liquid under pressure.

In the biological deodorization plant 3, a bypass pipe 35 is branched from the gas introduction pipe 32. The bypass pipe 35 is connected to the gas feed pipe 33. A first valve V ₁ is provided in the middle of the gas introduction pipe 32 and on the outlet side from the branch position of the bypass pipe 35, and a second valve V ₂ is provided in the middle of the bypass pipe 35. The first valve V ₁ and the second valve V ₂ can be opened and closed. By closing the first valve V ₁ and opening the second valve V ₂ , the odor gas introduced into the gas introduction pipe 32 is gas-liquid contact tower. 11 and is introduced into the biological deodorization tower 60 through the bypass pipe 35.

Thereby, since the odor gas can be directly introduced into the biological deodorization tower 60 via the bypass pipe 35 while cleaning the gas-liquid contact tower 11 in the biological deodorization plant 3, the gas-liquid contact tower 11 is cleaned. Odor gas processing can be continued for a while. The second valve V ₂ which opens during cleaning of the gas-liquid contact tower 11, by opening the first valve V ₁ is closed after completion of the washing, resume normal processing.

[Example 1]
In Example 1, the odor gas generated from the sludge storage tank was treated using an experimental apparatus simulating the biological treatment facility 1 of FIG. The odor gas contained ethanol as an organic substance, the sulfur compound contained hydrogen sulfide, methyl sulfide, methyl mercaptan, and the like, and also contained ammonia. The apparatus specifications and odor gas components were as follows.
<Gas-liquid contact tower>
Tower volume: 10L
Tower vertical height: 2.0m
Vertical height of absorption chamber: 1.5m
Vertical height of packed bed: 1.0m
Filler: Toyo Tire & Rubber Co., Ltd., 35mm cylindrical shape and bowl shape <biological deodorization tower>
Tower volume: 10L
Tower vertical height: 2.0m
Vertical height of absorption chamber: 1.5m
Vertical height of packed bed: 1.0m
Filling material: manufactured by Kurita Kogyo Co., Ltd., 100 mm × 100 mm × 1000 mm fiber molding <odor gas component>
Ethanol concentration: 140 volume ppm
Other organic matter concentration: 5 vol ppm
Hydrogen sulfide concentration: 200 volume ppm
Methyl sulfide concentration: 0.2 volume ppm
Methyl mercaptan concentration: 1.5 volume ppm
Other sulfur compound concentrations: 2.0 ppm by volume
Ammonia concentration: 0.5 volume ppm

The odor gas was vented to the gas-liquid contact tower at an air flow rate of 20 L / hr and a space velocity (SV) of 150 hr ⁻¹ . The acidic liquid was sprinkled from the watering means. The acidic liquid is circulated and used with a circulating water volume of 75 L, and tap water (pH 6.8) as make-up water and hydrochloric acid (70%) as acid are appropriately added to the acid bath to adjust the pH to 2.0 to 3.0. The concentration was adjusted to 1,000 mg / L.

The pretreatment gas taken out from the gas-liquid contact tower had a concentration of 4 ppm by volume of the entire organic substance and a concentration of 82.5 ppm by volume of the entire sulfur compound. The pretreatment gas was introduced into the biological deodorization tower and aerated under the conditions of an air flow rate of 20 L / hr, a space velocity (SV) of 300 hr ⁻¹ , and a linear velocity (LV) of 90 m / min. In the biological deodorization tower, tap water collected from the makeup water supply channel was sprinkled from the sprinkling means.

  The processing gas taken out from the biological deodorization tower in Example 1 had a concentration of the whole organic matter of 0.1 volume ppm and a concentration of the entire sulfur compound of 0.13 volume ppm. The results are shown in Table 1. The values in the table are all average values during the test period, and the symbol “ND” means that the value was below the detection limit.

  Table 2 shows the pressure loss in each of the gas-liquid contact tower and the biological deodorization tower during the 40-day test period.

  As shown in Table 1 and Table 2, pressure loss in the gas-liquid contact tower and the biological deodorization tower did not occur for 40 days from the start of the test, and the odor components in the odor gas could be removed well.

[Example 2]
In Example 2, the odor gas of Example 1 was processed under the same conditions as in Example 1 except that the biological deodorization tower was downsized using an experimental apparatus simulating the biological treatment facility 2 of FIG. The specifications of the biological deodorization tower are shown below.
<Biological deodorization tower>
Tower volume: 5L
Tower vertical height: 2.0m
Vertical height of absorption chamber: 1.5m
Vertical height of packed bed: 0.5m
Filler: Kurita Kogyo Co., Ltd., 100 mm × 100 mm × 500 mm fiber molded product

  In Example 2, the pretreatment gas extracted from the gas-liquid contact tower had a concentration of the whole organic substance of 3.5 ppm by volume and a concentration of the whole sulfur compound of about 50 ppm by volume. In addition, the processing gas taken out from the biological deodorization tower had a concentration of the whole organic substance of 0.1 volume ppm and a concentration of the whole sulfur compound of 0.14 volume ppm. The results are shown in Table 3. Table 4 shows the pressure loss in each of the gas-liquid contact tower and the biological deodorization tower during the 60-day test period.

  As shown in Table 3 and Table 4, pressure loss in the gas-liquid contact tower and the biological deodorization tower did not occur for 60 days from the start of the test, and the odor components in the odor gas could be removed well.

  As shown in Table 3 and Table 4, in Example 2, the pressure loss in the gas-liquid contact tower and the biological deodorization tower does not occur for 60 days from the start of the test as in Example 1, and the odor component in the odor gas is also good. Could be removed. In Example 2, the amount of water used for sprinkling, the amount of acid added, and the amount of wastewater generated from the biological treatment facility were less than in Example 1, and the biological deodorization tower was smaller than that in Example 1.

[Example 3]
In Example 3, a test was performed under the same conditions as in Example 2 using an experimental apparatus simulating the biological treatment facility 3 of FIG. The third embodiment is different from the second embodiment in that when the pressure loss of the gas-liquid contact tower reaches 2000 Pa or more, the liquid in the tank is supplied from the acid bath to the gas-liquid contact tower and aeration cleaning is performed. . The results are shown in Tables 5 and 6.

  As shown in Table 5 and Table 6, in Example 3, the same effect as in Example 2 was obtained, and further, no pressure loss occurred in the gas-liquid contact tower and the biological deodorization tower for 90 days or more from the start of the test. The gas treatment was continued.

[Comparative Example 1]
As Comparative Example 1, a test was conducted in which tap water having a pH of 6.8 was sprinkled into the gas-liquid contact tower instead of the acidic liquid by stopping the replenishment of acid to the acid liquid tank. In Comparative Example 1, the test was performed under the same conditions as in Example 1 except that neutral tap water was sprinkled instead of the acidic solution. The results are shown in Table 7 and Table 8.

  In Comparative Example 1, the pressure loss of the gas-liquid contact tower exceeded 2000 Pa after 20 days from the start of the test, and it was difficult to continue the test after 30 days from the start of the test. For this reason, the odor component density | concentration of the process gas during a test period also deteriorated after 20-day progress from the test start.

  As described above, according to the present invention, the blockage of the pretreatment unit in the biological deodorization plant of odor gas containing an organic substance and a sulfur compound as odor components can be effectively prevented over a long period of time.

  It can be used in biological deodorization plants such as methane gas generated in sludge treatment facilities.

It is a schematic diagram of the biological deodorizing plant which concerns on 1st Embodiment of this invention. It is a schematic diagram of the biological deodorizing plant which concerns on 2nd Embodiment of this invention. It is a schematic diagram of the biological deodorizing plant which concerns on 3rd Embodiment of this invention.

Explanation of symbols

1 to 3 Biological deodorization plant 10A to C Pretreatment unit 11 Gas-liquid contact tower 12 Absorption chamber 13, 63 Packing layer 13S Filling material 21, 64 Sprinkling means 22 Acid solution tank 32 Gas introduction pipe 33 Gas feed pipe 34 Processing gas pipe 40 Circulating means 42 Acid solution supply path 43 Acid supply path 44 Supply water path 60 Biological deodorization tower 62 Reaction chamber

Claims (5)

A pretreatment unit disposed in front of a biological deodorization tower in which sulfur-oxidizing bacteria are retained,
A gas-liquid contact tower having an absorption chamber into which an odor gas containing a sulfur compound and an organic substance is introduced;
A pretreatment unit for a biological deodorization plant, comprising: watering means for spraying an acidic liquid into the absorption chamber. An acid bath for holding the acid solution;
The acidic liquid sprayed into the absorption chamber has a return liquid path connected to the gas-liquid contact tower and the acid liquid tank, and an acid liquid supply path connected to the acid liquid tank and the watering means. A circulation means for removing the liquid from the gas-liquid contact tower and circulating it to the sprinkling means;
The pretreatment unit of the biological deodorization plant according to claim 1, further comprising: a drain supply path that sends a drain containing sulfuric acid discharged from the biological deodorization tower to the acid bath. A cleaning liquid path connected to the acid liquid tank and the gas-liquid contact tower, a liquid feeding means for supplying the liquid in the acid liquid tank to the gas-liquid contact tower via the cleaning liquid path, and the gas-liquid contact tower A cleaning device having an aeration means for aerating the interior;
A gas introduction pipe into which the odor gas is introduced and connected to the gas-liquid contact tower, a bypass pipe branched from the gas introduction pipe and connected to the biological deodorization tower, and the odor gas to the gas introduction pipe or the bypass The pretreatment unit for a biological deodorization plant according to claim 2, further comprising a gas flow path switching unit configured to flow through one of the pipes. An acid bath for holding the acid solution;
The acidic liquid sprayed into the absorption chamber has a return liquid path connected to the gas-liquid contact tower and the acid liquid tank, and an acid liquid supply path connected to the acid liquid tank and the watering means. A circulation means for removing the liquid from the gas-liquid contact tower and circulating it to the sprinkling means;
The biological deodorization plant according to any one of claims 1 to 3, further comprising a drain pipe for discharging the acidic liquid sprayed into the absorption chamber to maintain an organic substance concentration of the acidic liquid at 20,000 mg / L or less. Pre-processing unit. A method for biological deodorization of odorous gas containing sulfur compounds and organic substances,
A method for biological deodorization of odor gas, which is introduced into a biological deodorization tower in which sulfur-oxidizing bacteria are retained after the odor gas is introduced into a gas-liquid contact tower, the acidic liquid is sprinkled to absorb the organic matter in the acidic liquid.

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