JP2010247008A - Activated sludge tank, activated sludge treatment apparatus, gasified gas refining apparatus and activated sludge treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an activated sludge tank or the like capable of activating activated sludge and performing efficient treatment. <P>SOLUTION: In the activated sludge tank 12 for nitrifying and denitrifying organic matters and nitrogen inside one tank, calcium carbonate is supplied into the tank 12. The calcium carbonate is supplied as a carrier. In the activated sludge treatment apparatus B, an initial sedimentation basin 9, a coagulating sedimentation tank 10, an ammonia stripping portion 11, the activated sludge tank 12, and a final sedimentation tank 13 are serially connected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to an activated sludge tank, an activated sludge treatment apparatus, a gasification gas purification apparatus, and an activated sludge treatment method.

A method is known in which waste is pyrolyzed to obtain a pyrolysis gas containing a combustible gas, tar / light oil, and scattered char, and the pyrolysis gas is purified and used as a fuel gas.
For example, Patent Documents 1 and 2 show general technical levels of a gasification gas purification method and a fuel gas reformer.

And the drainage discharged | emitted from a gasification gas refiner | purifier is discharged after being purified through an activated sludge tank. This activated sludge tank is a technique for adsorbing and decomposing organic matter in wastewater by various species such as bacteria, protozoa, and metazoans, and is widely used for sewage treatment and industrial wastewater treatment.
Since the activated sludge treatment takes a long time, it is required to activate the activated sludge and perform the treatment efficiently. For this reason, for example, as shown in Patent Document 3, in a nitrogen removal method in which waste water is passed through a nitrification tank and then a denitrification tank in order to perform nitrification and denitrification, the waste water is discharged by introducing a carrier containing activated sludge or nitrifying bacteria into the nitrification tank. Techniques for maintaining near neutrality are disclosed.

JP 2007-45857 A JP 2005-60533 A JP 2001-79592 A

The activation of activated sludge is greatly influenced by the pH in the tank. In the activated sludge tank, fluctuations in pH when nitrifying and denitrifying organic matter and nitrogen are significant, and the treatment is not performed when the pH deviates from the reference value. For this reason, conventionally, an alkali such as an aqueous NaOH solution is used to adjust the pH.
However, there is a problem that it takes time to add the alkali as needed. Moreover, since it is difficult to grasp the exact amount of alkali input due to the properties of the waste water, there is a problem that the amount of input is excessive or insufficient.

  Moreover, the technique disclosed in Patent Document 3 is a two-tank type having a nitrification tank and a denitrification tank, and there is a problem that it is not suitable for nitrification / denitrification of organic substances and nitrogen in one tank.

  The present invention has been made in view of the above-described circumstances. An activated sludge tank, an activated sludge treatment apparatus, a gasification gas refining apparatus, and an activated sludge treatment method capable of activating activated sludge to achieve efficient treatment. The purpose is to propose.

In the activated sludge tank, the activated sludge treatment apparatus, the gasification gas purification apparatus, and the activated sludge treatment method according to the present invention, the following means are adopted in order to solve the above problems.
The first invention is characterized in that in an activated sludge tank that nitrifies and denitrifies organic matter and nitrogen in one tank, calcium carbonate is introduced into the tank.

  According to the present invention, the fluctuation of the pH of the activated sludge is reduced by the buffer effect of calcium carbonate. Therefore, activation of activated sludge can be achieved easily and reliably.

The calcium carbonate is added as a carrier.
Thereby, there is an effect that there is no case where the input amount becomes excessive or insufficient.

The second invention is an activated sludge treatment apparatus in which a first sedimentation tank, a coagulation sedimentation tank, an ammonia stripping, an activated sludge tank, and a final sedimentation tank are connected in series. It is characterized by using a sludge tank.
According to the present invention, activated sludge treatment can be performed efficiently.

According to a third aspect of the present invention, there is provided an oxidation reforming furnace for oxidizing and reforming a gasification gas from a gasification furnace, a heat exchanger for recovering heat by cooling the gasification gas reformed in the oxidation reforming furnace, A cooler that cools the gasification gas after cooling with a heat exchanger to condense water vapor, a booster that pressurizes the gasification gas cooled by the cooler, and a gasification gas pressurized by the booster and CO ₂ absorber that separates the CO ₂ cooling, the gasification gas purification system and a waste water treatment unit for treating the waste water generated in the condenser and the booster 6, the second to the wastewater treatment unit The activated sludge treatment apparatus according to the invention is connected.
According to the present invention, gasification gas purification can be performed efficiently.

  The fourth invention is characterized in that in the activated sludge treatment method in which organic matter and nitrogen are nitrified and denitrified in one tank, calcium carbonate is introduced into the tank.

  According to the present invention, the fluctuation of the pH of the activated sludge is reduced by the buffer effect of calcium carbonate. Therefore, activation of activated sludge can be achieved easily and reliably.

The calcium carbonate is added as a carrier.
Thereby, there is an effect that there is no case where the input amount becomes excessive or insufficient.

According to the present invention, the fluctuation of the pH of the activated sludge is reduced by the buffer effect of calcium carbonate. Therefore, activation of activated sludge can be achieved easily and reliably.
Moreover, since the calcium carbonate is added as a carrier, there is an effect that there is no case where the input amount becomes excessive or insufficient.

It is a figure which shows schematic structure of the gasification gas purification apparatus which concerns on embodiment of this invention. It is a figure which shows schematic structure of the activated sludge processing apparatus and activated sludge tank which concern on embodiment of this invention.

  Hereinafter, embodiments of an activated sludge tank, an activated sludge treatment apparatus, a gasification gas purification apparatus, and an activated sludge treatment method according to the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a gasification gas purification apparatus A according to an embodiment of the present invention.
As shown in FIG. 1, a gasification gas purification apparatus A such as coal includes a gasification furnace 1, an oxidation reforming furnace 2, a heat exchanger 3, a direct cooler 4, an indirect cooler 5, a booster 6, and a desulfurizer. and de-CO ₂ unit 7, and a waste water treatment unit 8.

  The gasification furnace 1 supplies gas and steam as gasification raw materials to generate gasification gas. That is, the gasification furnace 1 is set to gasify coal at a temperature of 700 ° C. to 900 ° C., and further, not only coal and water vapor but also tar content, char, and circulation from the waste water treatment device 8. The remaining gasification gas and the like are supplied.

  The oxidation reforming furnace 2 oxidizes and reforms the gasification gas from the gasification furnace 1 at a high temperature. That is, the oxidation reforming furnace 2 is set so that oxygen and air are introduced and hydrogen is burned to reach a high temperature of about 1100 ° C. to 1300 ° C. Further, cooling water is sprayed on the outlet side to gas temperature. Is reduced to about 1000 ° C. to 1200 ° C.

The heat exchanger 3 cools the gasified gas reformed in the oxidation reforming furnace 2 and recovers heat.
That is, the heat exchanger 3 is configured by a heat recovery structure such as a boiler.

  The direct cooler 4 cools the gasified gas after being cooled by the heat exchanger 3. That is, the direct cooler 4 is provided with a cooling means such as water spray, and directly cools the gasified gas from the heat exchanger 3.

  The indirect cooler 5 further indirectly cools the gasified gas cooled by the direct cooler 4. That is, the indirect cooler 5 includes indirect cooling means such as heat exchange pipes, and indirectly cools the gasified gas from the direct cooling means.

  The booster 6 pressurizes the gasified gas indirectly cooled by the indirect cooler 5. That is, the booster 6 is a gas compressor that pressurizes the gasified gas to about 1 MPa to 5 MPa, and lowers the saturated vapor concentration of tar in the gasified gas.

The desulfurizer / de-CO ₂ unit 7 removes sulfur / CO ₂ from the gasified gas pressurized by the booster 6. That is, the desulfurizer / de-CO ₂ unit 7 is configured to separate sulfur and CO ₂ from the gasification gas.

  The waste water treatment device 8 is for treating waste water generated by the direct cooler 4, the indirect cooler 5, and the booster 6. That is, the waste water treatment device 8 is connected to the direct cooler 4, the indirect cooler 5, and the booster 6, and treats the waste water generated in these to separate the combustible substance tar and char from the treated water. Is configured to do.

In such a configuration, the gasification gas purification apparatus A gasifies coal or the like in the gasification furnace 1 when processing the gasification gas.
Then, the gasified gas from the gasification furnace 1 is oxidized and steam reformed in the oxidation reforming furnace 2 to remove the tar content contained in the gasification gas.
The reformed gasification gas is cooled by the heat exchanger 3 to recover the heat, and the cooled gasification gas is cooled by the direct cooler 4 and the indirect cooler 5 to condense the water vapor remaining in the gasification gas.
The cooled gasification gas is pressurized by the booster 6, and the pressurized gasification gas is cooled by the desulfurizer / deCO ₂ unit 7 to separate sulfur and CO ₂ .
The gasification gas is purified and supplied to a desired supply destination, and CO ₂ is discarded and fixed.

On the outlet side of the oxidation reforming furnace 2, cooling water (quenching water) of about 20% (molar flow ratio) of the gasification gas is sprayed to lower the gas temperature to about 1000 ° C. to 1200 ° C. The durability of the heat exchanger 3 etc. is guaranteed. The sprayed cooling water is condensed with a temperature drop by the direct cooler 4, the indirect cooler 5, and the booster 6 on the downstream side, and sent to the waste water treatment device 8.
The waste water treatment device 8 separates the combustible substance tar and char from the waste water and supplies them to the gasification furnace 1.

Next, the activated sludge treatment apparatus B and the activated sludge tank 12 connected to the waste water treatment device 8 will be described with reference to FIG.
FIG. 2 is a diagram showing a schematic configuration of the activated sludge treatment apparatus B and the activated sludge tank 12 according to the embodiment of the present invention.

As shown in FIG. 2, a first sedimentation tank 9, a coagulation sedimentation tank 10, an ammonia stripping 11, an activated sludge tank (aeration tank) 12, and a final sedimentation tank 13 are connected to the waste water treatment device 8 in series. The facilities from the first settling tank 9 to the final settling tank 13 are called activated sludge treatment apparatus B.
Then, the treated water discharged from the waste water treatment device 8 passes through the activated sludge treatment device B, that is, the first settling basin 9 and the final settling tank 13 to be discharged to the outside as discharged water.

  The first sedimentation basin 9 precipitates and removes solids contained in the treated water discharged from the waste water treatment device 8.

  In the coagulation sedimentation tank 10, a coagulant is added to the treated water discharged from the sedimentation tank 9 first, and the solidified solids are precipitated and removed.

The ammonia stripping 11 removes ammonia nitrogen from the treated water discharged from the coagulation sedimentation tank 10 by a chemical reaction.
That is, ammonium ions (NH ₄ ⁺ ) and hydroxide ions (OH ⁻ ) in the treated water are reacted to change into water (H ₂ O) and ammonia gas (NH ₃ ), and the ammonia gas is released to the atmosphere. .

The activated sludge tank (aeration tank) 12 purifies by adsorbing and decomposing organic substances contained in the treated water discharged from the ammonia stripping 11 by bacteria.
Activated sludge is mainly composed of bacteria (bacteria), protozoa, metazoans and the like. Bacteria grow by eating organic matter in the treated water, and protozoa and metazoans grow by eating the bacteria and particulate organic matter. As a result, the organic matter and particulate matter in the treated water are reduced, so that the treated water is purified.

  And the final sedimentation tank 13 settles and removes the solid substance contained in the treated water discharged | emitted from the activated sludge tank 12, and discharges it outside as discharge water.

In the activated sludge tank 12, the influence of pH in the tank greatly influences when nitrifying and denitrifying organic substances (for example, C ₆ H ₁₂ O ₆ ) and nitrogen (ammonia nitrogen: NH ₄ ⁺ N ⁻ ) of treated water. If the pH deviates from the reference value, the purification process may not be performed. This is particularly noticeable in nitrification and denitrification reactions.

In order to avoid such an inconvenience, in the activated sludge tank 12, a carrier of calcium carbonate (CaCO ₃ ) is introduced into the tank. By introducing the calcium carbonate carrier into the activated sludge tank 12, the pH fluctuation of the activated sludge can be reduced.

This is because calcium carbonate freely changes between hydrogen carbonate ions (HCO ₃ ⁻ ) and carbonate ions (CO ₃ ²⁻ ) in the activated sludge tank 12 to reduce the pH fluctuation in the tank and maintain the equilibrium. This is because it works like this (buffer effect). Therefore, the pH of the activated sludge is stabilized near neutrality, and the activated sludge is activated.

Moreover, since the specific gravity of activated sludge increases by taking in Ca ^<2+> which activated sludge melt | dissolved, sedimentation improvement occurs. Therefore, it is possible to increase the sludge concentration MLSS, and it is also possible to treat wastewater having a higher concentration.

  In this way, by introducing the calcium carbonate carrier into the tank of the activated sludge tank 12, fluctuations in the pH of the activated sludge are reduced due to the buffer effect. Accordingly, it is possible to eliminate the use of an alkali such as an aqueous NaOH solution that has been added to maintain the pH of activated sludge. Moreover, it is effective in improving the sedimentation property of sludge.

  The reason why calcium carbonate is added as a carrier is that it is slightly soluble in water and can be easily retained in the tank of the activated sludge tank 12 for a long time. In other words, in the case of a carbonate having a high solubility, there is a possibility that it will immediately flow out of the tank.

  As described above, according to the activated sludge tank 12 according to the present embodiment, since calcium carbonate is introduced into the activated sludge tank 12 that nitrifies and denitrifies organic matter and nitrogen in one tank, the activated sludge tank 12 is activated by the buffer effect of calcium carbonate. The fluctuation of sludge pH is reduced. Therefore, activation of activated sludge can be achieved easily and reliably.

  Further, since the calcium carbonate is added as a carrier, there is an effect that the amount of the input becomes excessive or insufficient.

  Note that the operation procedures shown in the above-described embodiment, or the shapes and combinations of the components are examples, and can be variously changed based on process conditions, design requirements, and the like without departing from the gist of the present invention. is there.

A ... Gasification gas purification device, B ... Activated sludge treatment device, 1 ... Gasification furnace, 2 ... Oxidation reforming furnace, 3 ... Heat exchanger, 4 ... Direct cooler, 5 ... Indirect cooler, 6 ... Booster , 7 ... desulfurizer and de CO ₂ unit, 8 ... waste water treatment unit, 9 ... primary sedimentation, 10 ... flocculation tank, 11 ... ammonia stripping, 12 ... activated sludge tank, 13 ... final sedimentation tank

Claims (6)

In an activated sludge tank that nitrifies and denitrifies organic matter and nitrogen in one tank,
An activated sludge tank, wherein calcium carbonate is introduced into the tank.   The activated sludge tank according to claim 1, wherein the calcium carbonate is introduced as a carrier. In the activated sludge treatment equipment where the first sedimentation tank, coagulation sedimentation tank, ammonia stripping, activated sludge tank, and final sedimentation tank are connected in series,
An activated sludge treatment apparatus using the activated sludge tank according to claim 1 or 2 as the activated sludge tank. An oxidation reforming furnace for oxidizing and reforming gasification gas from the gasification furnace;
A heat exchanger for recovering heat by cooling the gasified gas reformed in the oxidation reforming furnace;
A cooler that cools the gasified gas after cooling with the heat exchanger and condenses water vapor;
A booster for pressurizing the gasified gas cooled by the cooler;
A CO ₂ absorber that separates CO ₂ by cooling the gasification gas pressurized by the booster;
A waste water treatment device for treating waste water generated in the cooler and the booster;
In a gasification gas purification apparatus comprising:
A gasification gas purification apparatus, wherein the activated sludge treatment apparatus according to claim 3 is connected to the waste water treatment apparatus. In the activated sludge treatment method that nitrifies and denitrifies organic matter and nitrogen in one tank,
An activated sludge treatment method, wherein calcium carbonate is introduced into the tank.   The activated sludge tank treatment method according to claim 5, wherein the calcium carbonate is added as a carrier.

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