JPH09271793A - Fluidized bed type biological treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the quantity of dissolved oxygen with hydrogen peroxide to prevent the deterioration of the treated water quality without causing the carryover of a carrier constituting a packed bed and without exerting a bad influence on living things stuck on the carrier by providing a means for feeding hydrogen peroxide to a fluidized bed type biological reaction tank. SOLUTION: In mid-way of a feeding pipe 10 for feeding waste washing water whose pH has been regulated to the bottom part of a biological reaction tank 6 from a pH regulating tank 1 by a pump, an injection pipe 12 for injecting hydrogen peroxide from a tank 11 by a pump P2 is connected. Downstream of the connected position, a line mixer 13 is installed in the feeding pipe 10 to uniformly mix hydrogen peroxide from a tank 11 with waste washing water to be fed to the biological reaction tank 6 and dissolve it in it. In this case, oxygen to be fed consists essentially of dissolved oxygen from an oxygen dissolving tank 8 fundamentally, but it is preferable that is be replenished with hydrogen peroxide by such a quantity that organic matter in waste washing water is decomposed in the biological reaction tank 6 to bring to an excessive quantity.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to organic matter concentration (TO
C) and a fluidized bed biological treatment apparatus for treating wastewater having a high ammonia concentration.

[0002]

2. Description of the Related Art Ultra-pure water is used for cleaning products in semiconductor and liquid crystal manufacturing plants. In recent years, however, due to restrictions on water intake and drainage, Japanese Patent Application No. 8- 180
As described in No. 38, as shown in FIG. 2, the washing wastewater is recovered, the pH is neutralized in the pH adjusting tank 1, and then the liquid is fed to the fluidized bed biological treatment apparatus 2 by a pump to supply isopropyl to the wastewater. Organic substances (TOC) such as alcohol, methanol, acetic acid, and acetone, and NH ₄ + are decomposed and removed, and the treated water is supplied from a tank 3 to a sterilizing tank to which Cl ₂ is continuously supplied as a sterilizing agent. From the flow-type biological treatment equipment by separating the bacterial cells from the flow type biological treatment device by supplying pressure to the membrane separation device 5 such as ultrafiltration membrane or microfiltration membrane with a pump for producing ultrapure water. The raw water is sent to the ultrapure water production system. The continuous addition of Cl _{2 in} the sterilization tank is for preventing the bacterial cells from adhering to the membrane surface of the membrane separation device at the subsequent stage and lowering the flux due to continuous operation.

As shown in FIG. 3, a conventional fluid-type biological treatment apparatus conventionally used comprises a biological reaction tank 6 and an oxygen dissolution tank 8, and the biological reaction tank 6 is in the form of granules or pellets carrying microorganisms. Having a packed bed 7 of activated carbon, the wastewater to be treated flows through the packed bed in an upward flow to spread the packed bed constantly. Then, an air diffuser 9 is provided in the oxygen dissolving tank 8, the air diffuser aerates air into the water and dissolves it in water, and the circulation pump P1 converts the water containing the dissolved oxygen in the oxygen dissolving tank into the biological reaction tank. Oxygen is supplied to the microorganisms adhering to the activated carbon in the bioreactor, which is supplied to the bottom of No. 6.

[0004]

As the waste water of the cleaning waste water is positively reused, the TOC in the cleaning water has been increased from 1 to 2 ppm at the highest in the past to several tens of ppm in recent years. May reach. In order to treat high-concentration cleaning wastewater with the fluid biological treatment device, it is necessary to supply the biological reaction tank with an amount of dissolved oxygen commensurate with the TOC in the wastewater. The method of increasing the supply amount of the recycled water to the biological reaction tank has been taken. However, if the amount of circulating water supplied to the biological reaction tank is increased, the expansion rate of the activated carbon, which is the carrier with the microorganisms attached in the biological reaction tank, will increase, and the activated carbon will carry over and mix with the treated water to cause the biological reaction tank to flow. There is a problem of spillage from. Further, in order to increase the amount of circulating water, the circulating pump P1 needs to have a large capacity, which increases the installation cost and running cost.

Therefore, in order to increase the amount of dissolved oxygen in the biological reaction tank without increasing the amount of circulating water from the oxygen dissolving tank, ozone O ₃ is washed as wastewater to be decomposed into water to generate oxygen. , And the reactivity and oxygen dissolution rate in the biological reaction tank were investigated. The reaction in which ozone is decomposed into water to generate oxygen is O ₃ → O ₂ + O ⁰ , and the oxygen dissolution rate is improved, but the oxygen (O ⁰ ) of its own nascent stage causes the reaction of activated carbon as a carrier. Microorganisms (bacteria) adhering to the surface are separated from the activated carbon and mixed with treated water from the biological reaction tank and flow out,
The quality of the treated water deteriorated significantly.

[0006]

Means for Solving the Problems Accordingly, the present inventors have
By using hydrogen peroxide (H ₂ O ₂ ) as an oxidant, it was confirmed that the amount of oxygen supplied to the biological reaction tank increased, the reaction in the biological reaction tank did not change, and the treated water quality was stable. The present invention was developed.

[0007]

Accordingly, the fluidized bed type biological treatment apparatus of the present invention has a fluidized bed type bioreactor holding a carrier having organisms attached thereto, and means for supplying oxygen to the biological reaction vessel. The fluidized bed biological treatment apparatus is characterized in that means for supplying hydrogen peroxide to the fluidized bed biological reaction tank is provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a fluidized bed type biological treatment apparatus according to the present invention. As in the conventional apparatus shown in FIG.
And the oxygen dissolution tank 8, the biological reaction tank 6 has a packed bed 7 of activated carbon in the form of granules or pellets carrying microorganisms, and the wastewater to be treated passes through the packed bed in an upward flow. , The packed bed is developed uniformly. Then, an air diffuser 9 is provided in the oxygen dissolving tank 8, the air diffuser aerates air into the water and dissolves it in water, and the circulation pump P1 converts the water containing the dissolved oxygen in the oxygen dissolving tank into the biological reaction tank. Oxygen is supplied to the microorganisms adhering to the activated carbon in the bioreactor, which is supplied to the bottom of No. 6.

An injection pipe 12 for injecting hydrogen peroxide from a tank 11 by a pump P2 is connected in the middle of a supply pipe 10 for supplying pH-adjusted cleaning wastewater from the pH adjustment tank 1 to the bottom of the biological reaction tank 6 by a pump. There is. Then, a line mixer 13 is provided in the supply pipe 10 downstream of the connection position, and the cleaning wastewater supplied to the biological reaction tank through the supply pipe 10 is added to the tank 1
The hydrogen peroxide from 1 is mixed and dissolved uniformly.

Basically, the oxygen to be supplied is mainly dissolved oxygen from the oxygen dissolving tank. However, hydrogen peroxide is replenished with hydrogen peroxide in an amount sufficient to decompose TOC in the cleaning wastewater in the biological reaction tank. It is preferable that the amount is excessive. For example, a TOC monitor 14 is connected to the supply pipe 10 upstream of the connection position of the injection pipe 12, the TOC monitor of the wash waste water is measured by the TOC monitor, and a pump P2 of the injection pipe is supplied according to the TOC of the wash waste water.
May be controlled to control the injection amount of hydrogen peroxide. or,
The amount of dissolved oxygen contained in the cleaning wastewater itself and the amount of dissolved oxygen supplemented by the circulating water from the oxygen dissolving tank are T of the cleaning wastewater.
Hydrogen peroxide may be used to supplement the amount of dissolved oxygen that is insufficient to decompose OC.

In the embodiment shown in FIG. 1, hydrogen peroxide was injected from the neutralization tank 1 into the supply pipe 10 for washing wastewater to the biological reaction tank 6. However, the hydrogen peroxide was neutralized or a recovery water tank in front of it. Alternatively, it may be injected into an oxygen dissolution tank or a line having a circulation pump P1 from the oxygen dissolution tank to the biological reaction tank. Furthermore, even if hydrogen peroxide is injected into the biological reaction tank, there is almost no adverse effect on the microorganisms attached to the carrier, and especially when the hydrogen peroxide is continuously supplied to the biological reaction tank, the biological activity is reduced. Since it does not interfere, it may be directly injected into the bioreactor.

Although an oxygen dissolving tank is used as an oxygen supplying means to the biological reaction tank, oxygen is mixed with compressed air and water by an ejector and supplied to a pressure tank as described in the above-mentioned prior application. However, any device such as one that supplies pressurized water from this pressurized tank to the biological reaction tank can be used.

As cleaning wastewater of ultrapure water, ultrapure water to which 10 ppmasC of isopropyl alcohol was added was treated by the apparatus shown in FIGS. In addition, 20-40 mesh coal-based granular activated carbon is used as the carrier for the biological reaction tanks of both devices, the carrier amount is 15 minutes as HRT, the amount of washing wastewater supplied, and the oxygen dissolution tank to the biological reaction tank. The circulating water amount is 1: 1. In the apparatus of the present invention shown in FIG. 1, 50 ppm of hydrogen peroxide was injected into the supply pipe 10. As a result, the TOC of the treated water in the apparatus shown in FIG.
It became 400 to 800 ppb from pm, but the TOC of treated water when hydrogen peroxide in FIG. 1 was injected was 10 ppm.
To 250 ppb. As a result, it has been found that the TOC of the treated water deteriorates fluctuatingly in the apparatus of FIG. 3 due to the shortage of dissolved oxygen, while the TOC can be reduced and stabilized by adding hydrogen peroxide.

[0014]

As is clear from the above, since the amount of circulating water to the biological reaction tank is not increased, carry-over of the carrier constituting the packed bed does not occur, and the organisms attached to the carrier are not adversely affected. Hydrogen peroxide can increase the amount of dissolved oxygen and prevent deterioration of treated water quality.

[Brief description of drawings]

FIG. 1 is an explanatory view of a fluidized bed type biological treatment apparatus according to the present invention.

FIG. 2 is a flow sheet of a device for collecting and purifying cleaning wastewater of ultrapure water.

FIG. 3 is an explanatory view of a conventional fluidized bed type biological treatment apparatus.

[Explanation of symbols]

 6 Bioreaction Tank 7 Packed Bed of Bioreaction Tank 8 Oxygen Dissolution Tank (Oxygen Supply Means) 9 Diffuser of Oxygen Dissolution Tank 10 Supply Pipe for Washing Wastewater to Bioreaction Tank 11 Hydrogen Peroxide Tank 12 Hydrogen Peroxide Injection tube (hydrogen peroxide supply means) 13 line mixer

Claims (1)

[Claims] 1. A fluidized bed bioreactor comprising: a fluidized bed bioreactor holding a carrier having organisms attached thereto; and a means for supplying oxygen to the bioreactor. A fluidized bed-type biological treatment apparatus, characterized in that a means for supplying hydrogen peroxide is provided in the.