JP2008114166A - Treatment apparatus of voc gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment apparatus of a VOC gas constituted so as to perform stable and economical operation while supplying a necessary minimum amount of nutriments by minimizing the amount of the nutriments flowing out along with drainage. <P>SOLUTION: In the treatment apparatus for collecting the exhaust gas a containing water soluble VOC and guiding the collected gas to a biological treatment tank 1 filled with carrier having microorganisms adhered thereto to biologically decompose the same, a storage water tank 15 for storing circulating water (c) containing the nutriments is provided on the bottom part of the biological treatment tank 1, a hopper like separation water tank 13 for receiving the washing water (d) falling from a carrier filling bed 11 is provided to the upper part of the storage water tank 15 and the solid substance of excess microorganisms or the like contained in the washing water (d) is sedimented on the bottom part of the separation water tank 13 while supernatant water containing the nutriments is allowed to overflow to the storage water tank 15 from the separation water tank 13. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention replenishes the minimum amount of nutrients by minimizing the amount of nutrients flowing out along with the drainage when biologically treating exhaust gases containing VOCs (volatile organic compounds). The present invention also relates to a VOC gas processing apparatus that performs stable and economical operation.

  Conventionally, various VOC gases are generated in paint factories, printing factories, chemical factories, etc. due to paints, adhesives, and chemical substances used as raw materials. Therefore, it is necessary to take measures to prevent bad odor pollution and photochemical oxidant generation due to VOCs. Therefore, after these gases are collected as exhaust gas, they are usually led to a combustion furnace and subjected to oxidative decomposition treatment.

However, in the conventional combustion method, fire must be used in a factory that handles flammable VOCs, and fuel such as heavy oil is required for auxiliary combustion. Therefore, in recent years, it is safe and most energy efficient. Biological treatment research is ongoing.
In the most efficient packing method for biological treatment, usually, decomposing microorganisms are attached to the surface of a carrier such as ceramic or plastic, these carriers are filled to a predetermined height, and the packed layer is replenished with moisture necessary for the microorganisms. However, biodegradation is performed by introducing VOC gas.

On the other hand, in order to maintain the amount of microorganisms, it is necessary to grow more than the microorganisms that die, but since microorganisms require trace nutrient sources such as nitrogen and phosphorus in addition to VOC as a carbon source, nutrients It is supplied to the microorganisms by sprinkling water in which the water is dissolved.
In addition, if microorganisms grow more than necessary, the gap between the filled carriers decreases, the pressure loss increases, and it becomes difficult for the VOC gas to flow. Therefore, it is necessary to separate a part of the microorganisms from the carrier.
Usually, the separated microorganisms and the solid matter trapped between the carrier and the carrier are dropped into a water tank at the bottom by performing watering or washing operation of the carrier packed bed to prevent clogging of the carrier.

By the way, because nutrients are consumed with the growth of microorganisms, it is necessary to replenish nutrients to the bottom tank, but because excess sludge microorganisms and solids accumulate in the tank, For the purpose of discharging these, it is usually overflowed by supplying fresh water in addition to nutrients.
Since the overflowed wastewater contains nutrients in addition to the solids that should be discharged, the nutrients are wasted.
In particular, when the VOC concentration is high, it is necessary to increase the nutrient concentration in proportion to the VOC concentration, so that there is a problem in that the amount of nutrient discharged with the drainage increases and the running cost increases. there were.

  In view of the problems of the above-mentioned conventional VOC gas processing apparatus, the present invention is stable while supplying the minimum amount of nutrients by minimizing the amount of nutrients flowing out along with drainage. It is another object of the present invention to provide a VOC gas processing apparatus capable of operating economically.

  In order to achieve the above object, a VOC gas processing apparatus of the present invention collects exhaust gas containing VOC, and guides it to a biological processing tank filled with a carrier to which microorganisms are attached, thereby biodegrading the VOC gas processing apparatus. In addition, a reservoir tank for storing circulating water containing nutrients is provided at the bottom of the biological treatment tank, and a hopper-shaped separation tank for receiving the wash water dropped from the packed bed of the carrier is provided at the top of the reservoir tank for cleaning. It is characterized in that solid matter such as surplus microorganisms contained in water is precipitated at the bottom of the separation water tank, and the supernatant water containing the nutrient is overflowed from the separation water tank to the storage water tank.

  In this case, a drainage pipe for discharging the precipitated solid matter can be provided in the separation water tank, and a valve or a drainage pump can be provided in the drainage pipe.

According to the VOC gas treatment apparatus of the present invention, surplus microorganisms separated from the carrier surface of the packed bed and solid matter trapped in the gap between the carriers are washed away with water sprayed from the water spray pipe and dropped from the carrier packed bed. The washed water received in a hopper-shaped separation water tank and allowed to stand still causes solids such as excess sludge to settle to the bottom of the separation water tank, and overflow the supernatant water containing nutrients from the separation water tank. Since the nutrient solution is reused by returning to the storage tank, the running cost due to the consumption of the nutrient solution can be reduced without wastefully discharging the nutrient solution.
In addition, by discharging solids such as excess sludge from the separation tank, it is possible to prevent troubles such as sludge and other organic matter decaying and producing malodors during operation, and supplying appropriate moisture and nutrients. However, since it can be operated while maintaining a desired amount of microorganisms, it has an effect of maintaining stable processing performance.

  In addition, a drainage pipe for discharging the precipitated solid matter is provided in the separation water tank, and by providing a valve or a drainage pump in the drainage pipe, the valve is opened intermittently or the drainage pump is operated intermittently. The solid matter precipitated at the bottom of the separation water tank can be discharged periodically.

  Embodiments of a VOC gas processing apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the VOC gas processing apparatus of the present invention.
This VOC gas processing apparatus collects exhaust gas a containing VOC, leads it to a biological treatment tank 1 filled with a carrier to which microorganisms are attached, and biodegrades the nutrient solution at the bottom of the biological treatment tank 1 And a hopper-like separation water tank 13 for receiving the wash water d dropped from the carrier packed bed 11 is provided on the upper part of the reservoir water tank 15 and contained in the wash water d. Solid substances such as surplus microorganisms are allowed to settle to the bottom of the separation water tank 13 and the supernatant water containing nutrients is allowed to overflow from the separation water tank 13 to the storage water tank 15.
The separation water tank 13 is provided with a drainage pipe for discharging the precipitated solid matter, and a valve 14 or a drainage pump (not shown) is provided in the drainage pipe, and the valve 14 is intermittently opened or the drainage pump is intermittently provided. The solid matter settled at the bottom of the separated water tank can be discharged periodically by operating in the above manner.

The exhaust gas a collected and discharged by the exhaust fan 2 from a VOC generation source such as a painting factory is guided to the biological treatment tank 1.
The biological treatment tank 1 is provided with a packed bed 11 filled with a carrier having microorganisms attached to the central part, and a sprinkling pipe 12 having a spray nozzle disposed on the upper part, and is stored by a watering pump 3 from a water tank 15 at the bottom. A pipe for supplying the circulating water c inside the water tank 15 to the water spray pipe 12 is arranged.

As the microorganism-adhering carrier, various materials such as ceramics, plastics, synthetic fibers processed into various shapes, or foamed ones can be used, and are not particularly limited. It is desirable to use a carrier made of a material that is large in quantity and difficult to wear.
In addition, the height of the packed bed 11 is set to a desired height in consideration of the weight of the carrier, air permeability, the amount of biological adhesion, etc., but is not limited to one stage, and may be stacked in two or three stages. Is possible.

On the other hand, a hopper-shaped separation water tank 13 for receiving the washing water dropped from the carrier packed bed 11 is provided on the upper part of the storage water tank 15, and further, a drain pipe for draining from the bottom of the separation water tank 13 is provided. A valve 14 or a drain pump (not shown) is provided in the drain pipe.
A gap is provided between the inverted conical separation water tank 13 and the inner wall of the biological treatment tank 1, so that overflow water from the separation water tank 13 falls into the storage water tank 15.

Next, the operation of the VOC gas processing apparatus of this embodiment will be described.
In FIG. 1, VOC in the exhaust gas a sent to the lower part of the packed bed 11 of the biological treatment tank 1 by the exhaust fan 2 gradually flows into the moisture on the surface of the carrier while flowing through the gap between the packed bed carriers. It is usually decomposed into carbon dioxide and water by microorganisms that dissolve and subsequently adhere to the carrier.
Therefore, the VOC concentration decreases as it flows upward in the packed bed 11, is removed to a concentration corresponding to the amount of microorganisms and the contact time, and is discharged out of the tank as the processing gas b.
At this time, in addition to VOC as a carbon source, a decomposing microorganism grows while taking in a trace amount of nutrient sources such as nitrogen and phosphorus.

Further, since it is necessary to dissolve the VOC in moisture before the VOC is taken into the microorganism, it is necessary to keep the carrier always wet with water.
Therefore, the watering pump 3 is operated at intervals of about 1 to 3 hours, and the circulating water c containing nutrients is sprinkled from the watering pipe 12.
Since the nutrient contained in the circulating water c is consumed as the VOC is decomposed by the microorganisms and the microorganisms are propagated, it is necessary to supply the nutrient and the makeup water f to the storage tank 15 from another pipe.

On the other hand, from the state where the decomposed microorganisms are sufficiently spread on the carrier, the microorganisms grown will block the gap between the carriers and the pressure loss will increase, making it difficult for the exhaust gas to flow. This prevents clogging of the carrier gap.
Although the method for this is omitted in the figure, a mechanical stirring device is provided in the packed bed 11 of the carrier, a nozzle is provided in the packed bed and pressure water is injected, or a bottom plate is provided in the packed bed. It is necessary to provide a structure such as providing and filling the water up to a predetermined water level for washing.

As a result, microorganisms separated from the carrier and solid matter such as dust in the exhaust gas trapped in the carrier gap are included in the washing water d and fall from the packed bed 11 to the separation water tank 13.
Since solids such as surplus microorganisms and dust have a high specific gravity, they settle in the separation water tank 13 in a short time and are collected at the bottom center of the separation water tank 13.
Accumulated solid matter is discharged out of the tank as waste water e that concentrates solid matter at high concentration by opening the valve 14 intermittently (regularly) or by operating the drain pump intermittently (regularly). Is done.
Moreover, the separated supernatant water overflows from the upper part of the separation water tank 13 and falls to the lower storage tank 15, and the residual components of the nutrient contained in the supernatant water are reused as the circulating water c. .

As described above, the VOC gas treatment apparatus of the present embodiment is configured to wash away excess microorganisms separated from the carrier surface of the packed bed 11 and solid matter trapped in the gaps of the carrier with the water sprayed from the water spray pipe 12. The washing water d dropped from the packed bed is received in the hopper-shaped separation water tank 13 and allowed to stand, thereby precipitating solids such as excess sludge to the bottom of the separation water tank 13 and separating the supernatant water containing nutrients. Since overflowing from the water tank 13 and returning to the lower storage tank 15 to reuse the nutrient, the running cost due to consumption of the nutrient can be reduced without wastefully discharging the nutrient.
In addition, by discharging solid matter such as excess sludge from the separation water tank 13, it is possible to prevent troubles such as sludge and other organic matter decaying during operation and causing bad odors. Since it can be operated while supplying a desired amount of microorganisms while being supplied, it has the effect of maintaining stable processing performance.

  As mentioned above, although the processing apparatus of the VOC gas of this invention was demonstrated based on the Example, this invention is not limited to the structure described in the said Example, The structure described in the Example is combined suitably, etc. The configuration can be changed as appropriate without departing from the spirit of the invention.

  The VOC gas processing apparatus of the present invention replenishes the minimum amount of nutrients by minimizing the amount of nutrients flowing out along with drainage when treating exhaust gas containing VOCs with microorganisms. However, since it has the characteristic of being able to operate stably and economically, it can be used widely and suitably for the use of a processing apparatus for VOC gas by microorganisms.

It is sectional drawing which shows one Example of the processing apparatus of the VOC gas of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Biological treatment tank 11 Packing layer 12 Sprinkling pipe 13 Separation water tank 14 Valve 15 Reservoir tank 2 Exhaust fan 3 Sprinkling pump a Exhaust gas b Treatment gas c Circulating water d Washing water e Drainage f Nutrient and makeup water

Claims (2)

  In a VOC gas treatment apparatus that collects exhaust gas containing VOC and guides it to a biological treatment tank filled with a carrier to which microorganisms are attached and biodegrades it, circulating water containing nutrients is stored at the bottom of the biological treatment tank. A reservoir tank is provided, and a hopper-shaped separation water tank that receives the wash water dropped from the packed bed of the carrier is provided at the top of the reservoir tank, and solid matter such as surplus microorganisms contained in the wash water is transferred to the bottom of the separation water tank. A processing apparatus for VOC gas characterized in that the supernatant water containing nutrients is allowed to overflow from the separation water tank to the storage water tank.   2. The VOC gas processing apparatus according to claim 1, wherein a drain pipe for discharging the precipitated solid matter is provided in the separation water tank, and a valve or a drain pump is provided in the drain pipe.

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