WO2013015128A1

WO2013015128A1 - Biological treatment method and treatment device for amine-containing waste water

Info

Publication number: WO2013015128A1
Application number: PCT/JP2012/067817
Authority: WO
Inventors: 小野　徳昭; 哲朗深瀬
Original assignee: 栗田工業株式会社
Priority date: 2011-07-22
Filing date: 2012-07-12
Publication date: 2013-01-31
Also published as: JP2013022536A; CN103648989B; TW201318980A; JP5799633B2; CN103648989A; KR20140037837A

Abstract

In biological treatment of amine-containing waste water, which is organic waste water in an ultrapure water recovery system, the treatment during fluctuating conditions is stabilized and stable treatment is carried out at the start of operation, and during fluctuating load and waste water composition. A method for introducing amine-containing waste water, which is organic waste water in an ultrapure water recovery system, to a biological treatment tank to carry out biological treatment, wherein an acid is added to the biological treatment tank on the basis of the pH value of the liquid in the biological treatment tank. When amine-containing waste water, which is organic waste water in an ultrapure water recovery system, is to be biologically treated, an increase is detected in the pH of the liquid in the biological treatment tank caused by ammonia generated by amine oxidation, and an acid is added to the biological treatment tank in accordance with the pH value, whereby the liquid in the biological treatment tank can be adjusted to an optimal pH value. Therefore, stable and efficient treatment can be carried out without a reduction in the activity of the biological treatment, even during operation startup, or during fluctuating waste water composition or waste water load.

Description

Biological treatment method and treatment equipment for amine-containing wastewater

The present invention relates to a method and apparatus for biological treatment of amine-containing organic wastewater from an ultrapure water recovery system.

From manufacturing processes of semiconductors, liquid crystals, plasma displays, etc., ultrapure water recovery system organic wastewater contains various amines such as ethanolamine and alkaline components such as N-methylformamide and tetramethylammonium hydroxide (TMAH). Amine-containing wastewater containing is discharged. As the biological treatment method for these amine-containing wastewater, the activated sludge method (AS), the membrane separation activated sludge method (MBR), the fluidized bed biological treatment method (FB), and the like are applied. In either case, in order to neutralize the alkaline components in the wastewater and adjust the pH to about 6.5 to 7.5, which is suitable for biological treatment, a pH adjustment tank is provided in front of the biological treatment tank to automatically adjust the pH. Adjustment is performed (Patent Document 1).

In the biological treatment tank, amine is biodegraded, and nitrification occurs by oxidizing the ammonia produced by the biodegradation into nitric acid. The production of this nitric acid lowers the pH in the biological treatment tank. For this reason, in a biological treatment tank, it is necessary to add alkali and maintain pH neutral.
In order to reduce the amount of alkali added to neutralize the pH that has decreased due to this nitrification, a part of the alkali may be recovered by performing a denitrification treatment. This denitrification process is often employed in MBR. As the denitrification method, a circulation method using amine in wastewater as an organic substance source is usually used.

JP-A-8-80497

In the conventional biological treatment equipment, when the treatment is performed well, the optimum operating conditions can be obtained by adding a slight amount of acid to the pH adjustment tank in front of the biological treatment tank and adding alkali to the biological treatment tank. Can be maintained.
However, at the start of operation or when the drainage composition or drainage load changes extremely, there is a problem that the pH of the liquid in the biological treatment tank changes greatly and the treatment becomes unstable. This problem was remarkable when the amine-containing wastewater was treated from the ultrapure water recovery system.

The present invention stabilizes the treatment at the time of fluctuation of conditions in the biological treatment of amine-containing organic wastewater from the ultrapure water recovery system, and can perform stable treatment even at the start of operation, wastewater composition and load fluctuation. It is an object of the present invention to provide a biological treatment method and treatment apparatus for wastewater contained.

The present inventors examined the cause of the instability of the treatment at the time of condition change in the biological treatment of amine-containing wastewater that is an ultrapure water recovery organic wastewater, and obtained the following knowledge.

As described above, when amine biodegradation progresses in the biological treatment tank, ammonia is first generated by decomposition of the amine to raise the pH, and then ammonia is oxidized to nitric acid to lower the pH. Follow.
When these reactions occur in biological treatment tanks close to plug flow or multi-stage biological treatment tanks, as the treatment progresses, in the middle part of the biological treatment tanks, pH increases due to ammonium generation due to amine decomposition, and acclimatization occurs. As the process proceeds, the pH decreases due to the production of nitric acid by oxidation of ammonia. Therefore, in the biological treatment tank, it is necessary to add both acid and alkali in all parts. That is, it is necessary to add an acid in the pH increase region and an alkali in the pH decrease region.

In the biological treatment of amine-containing wastewater, which is normal general wastewater such as sewage, food wastewater, chemical wastewater, etc., the alkalinity of the wastewater is high, so the pH of Small fluctuation. For this reason, in many cases, it is not necessary to add acid or alkali to the biological treatment tank, and the pH of the biological treatment tank can be maintained sufficiently neutral only by alkali recovery by denitrification. Even when the alkalinity is exceptionally low, a slight amount of alkali may be added to the biological treatment tank, and in any case, it is not necessary to add acid to the biological treatment tank. That is, conventionally, in the biological treatment of amine-containing wastewater from general wastewater, there is no recognition that ammonia generation in the biological treatment tank causes a decrease in biological treatment activity, and acid is added to the biological treatment tank. It wasn't.

However, the organic wastewater from the ultrapure water recovery system such as semiconductors, liquid crystals, plasma displays, etc. has only a slight amount of organic matter dissolved in the ultrapure water and contains almost no alkalinity. The pH fluctuation is extremely large. For this reason, it is greatly affected by the pH increase due to ammonia generated by the decomposition of amine, and greatly deviates from the pH range necessary for biological reaction. As a result, the biological treatment activity is reduced and the treatment becomes unstable. Become. This tendency is promoted when the inflow of wastewater into the biological treatment tank becomes intermittent, and is reduced as it approaches continuously. This tendency is further promoted when the biological treatment tank is a plug flow type, and is reduced when the biological treatment tank is a fully mixed biological treatment tank.

The present invention has been achieved on the basis of such knowledge, and the gist thereof is as follows.

[1] In a method for biological treatment by introducing amine-containing wastewater, which is organic wastewater from ultrapure water recovery, into a biological treatment tank, an acid is added to the biological treatment tank based on the pH value of the liquid in the biological treatment tank A biological treatment method for amine-containing wastewater.

[2] The method for biological treatment of amine-containing wastewater according to [1], wherein the amine-containing wastewater is continuously introduced into the biological treatment tank having a structure in which the solution in the tank is completely mixed.

[3] A biological treatment method for amine-containing wastewater, wherein in [1] or [2], an acid is added to the biological treatment tank so that the pH value is 8.5 or less.

[4] In a biological treatment apparatus for amine-containing wastewater that is an ultrapure water recovery system organic wastewater, a biological treatment tank into which the amine-containing wastewater is introduced, a pH meter that measures the pH of the liquid in the biological treatment tank, An amine-containing wastewater biological treatment apparatus, comprising: an acid addition means for adding an acid to the biological treatment tank based on a measurement value of the pH meter.

[5] In [4], the biological treatment tank is a biological treatment tank having a structure in which the solution in the tank is completely mixed, and the amine-containing wastewater is continuously introduced into the biological treatment tank. Biological treatment equipment for wastewater containing amine.

[6] The biological treatment apparatus for amine-containing wastewater according to [4] or [5], wherein an acid is added by the acid addition means so that a measured value of the pH meter is 8.5 or less.

According to the present invention, in the biological treatment of amine-containing wastewater that is an ultrapure water recovery system organic wastewater, an increase in the pH of the liquid in the biological treatment tank due to ammonia generated by the oxidation of amine is detected and the pH value is determined. By adding acid to the biological treatment tank, the solution in the biological treatment tank can be adjusted to an optimum pH value for biological treatment. A stable and efficient treatment can be performed without reducing the activity of the treatment.

Hereinafter, embodiments of the biological treatment method and treatment apparatus for amine-containing wastewater of the present invention will be described in detail.

The amine-containing wastewater to be treated in the present invention is organic wastewater from ultrapure water recovery systems such as semiconductors, liquid crystals, plasma displays, and such ultrapure water recovery system organic wastewater is usually as follows. Water quality.
<Water quality of organic wastewater from ultrapure water recovery system>
pH: 8-11
TOC: 10-200mg / L
TOC component: amine such as monoethanolamine, N-methylformamide, TMAH, etc. Ratio of amine in TOC component: 50-95%

In the present invention, when the amine-containing organic waste water from the ultrapure water recovery system is introduced into the biological treatment tank for biological treatment, the pH of the liquid in the biological treatment tank is measured, and the biological treatment is performed based on the measured value. Add acid to the bath.

As described above, the organic waste water from the ultrapure water recovery system is usually alkaline with a pH of about 8-11.
Since the wastewater does not contain nutrients necessary for biological treatment, it is preferable to add the necessary nutrients for biological treatment.

There is no restriction | limiting in particular as a biological treatment tank, A normal aeration tank can be used. As described above, if the biological treatment tank is a plug flow type, the influence of pH fluctuation is large. Therefore, as the biological treatment tank, a tank in which the liquid in the tank can be completely mixed, specifically, the following (1) and / or Alternatively, it is preferable to use the one as in (2), and it is preferable to use a single tank structure without providing a plurality of biological treatment regions in series.
(1) Biological treatment tank with full aeration (2) As the tank shape, the length from drainage inflow to outflow is less than 5 times the width

As described above, when wastewater is intermittently introduced into the biological treatment tank, the influence of pH fluctuation becomes large. Therefore, it is desirable to introduce the wastewater continuously into the biological treatment tank, preferably at a constant flow rate.

The acid is added to the biological treatment tank so that the pH value of the liquid in the biological treatment tank becomes pH 7 to 8.5 suitable for biological treatment. Therefore, when the pH value of the liquid in the biological treatment tank exceeds 8.5, an acid such as sulfuric acid or hydrochloric acid is added to adjust the pH so that the liquid in the biological treatment tank has a pH of 8.5 or less. It is preferable. When the pH of the liquid in the biological treatment tank is below 7, it is preferable to add an alkali such as sodium hydroxide or potassium hydroxide.

The addition of acid or alkali based on the pH value of the liquid in the biological treatment tank can be automatically performed by a chemical injection means linked to a pH meter provided in the biological treatment tank.

The biological treatment tank may be filled with a carrier for holding sludge. The carrier may be either a fluidized bed or a fixed bed, but a fluidized bed type carrier is preferred for mixing the liquid in the tank, and the filling rate is preferably about 10 to 50% with respect to the tank volume.

Hereinafter, the present invention will be described more specifically with reference to experimental examples, examples and comparative examples.

In the following experimental examples, examples and comparative examples, sulfuric acid was added to water of pH 9.5 to which nutrient salts were added as follows, to the amine-containing organic waste water from the ultrapure water recovery system of the following water quality liquid crystal factory. Then, the water adjusted to pH 7.5 was treated as raw water.

<Organic wastewater quality>
TOC: 103mg / L
Main component: Monoethanolamine Other components: N-methylformamide, TMAH, etc. (90% or more of total TOC in total of monoethanolamine, N-methylformamide, and TMAH)
In addition, since P, Ca, K, Mg, Na, S, etc. were hardly contained in the said organic waste water, it becomes 1 mg / L as a phosphorus conversion addition amount in total with disodium phosphate and 1 potassium phosphate. In addition, magnesium sulfate was added so as to be 1 mg / L as a magnesium equivalent addition amount, and calcium chloride was added as 1 mg / L as a calcium equivalent addition amount. The pH of the waste water after the addition was 9.5.

[Experimental Example 1]
The raw water was biologically treated using a biological treatment apparatus in which three 3L aeration tanks were connected in series, and each aeration tank was filled with 20% by volume of a 10 mm square polyurethane sponge carrier. A pH meter is installed in the first aeration tank (first stage aeration tank) and the third aeration tank (third stage aeration tank), and when the measured value of the pH meter decreases to 7.0, 1N NaOH aqueous solution is added. To be added. The air was aerated so that all three tanks would be 3 vvm, a small amount of biological sludge from the septic tank wastewater in other places was added, and raw water was continuously passed through the three aeration tanks to start treatment. The residence time in the aeration tank was 3 hours each, for a total of 9 hours.
As a result, the TOC (soluble TOC) of the treated water (outflow water of the third aeration tank) on the second day of treatment was 50 mg / L, and the treated water TOC was 42 mg / L on the third day of treatment.
When the pH was measured, the treated water had a pH of 9.0, and the liquid in the second aeration tank (second stage aeration tank) rose to pH 8.8. Even on the fourth day, the TOC of the treated water was 39 mg / L, pH 8.8 to 9.0.
Thereafter, the treatment was continued for 2 weeks, but the treated water TOC did not become 20 mg / L or less.

[Comparative Example 1]
Using the same biological treatment apparatus as in Experimental Example 1, 20% by volume of a sponge carrier to which nitrifying bacteria were sufficiently adhered separately was charged, and biological treatment was performed by passing raw water of the same water quality under the same conditions.
As a result, the treated water TOC became 10 mg / L after 4 days of water flow and decreased to 3 mg / L after 5 days. The ammonia nitrogen concentration of the treated water was 2 mg / L or less, and the nitrate nitrogen concentration was 40 mg / L or more.
Since the treated water TOC of 3 to 5 mg / L was continued for one week, the load was increased three times.
As a result, the nitrate nitrogen of the treated water was hardly detected on the next day after the increase in load, and ammonia nitrogen was detected at about 45 mg / L instead. Further, the TOC exceeded 20 mg / L, and the treated water TOC of 20 to 25 mg / L was continued for 3 days. The pH of the treated water was 8.8 to 9.1.
Thereafter, the treatment gradually deteriorated, and after one week, the treated water TOC exceeded 30 mg / L.
Since the process did not recover, the load was reduced and restored. However, after that, the treatment hardly recovered for more than one week, and the treated water TOC did not become 10 mg / L or less.

[Example 1]
Comparative Example 1 is set such that a pH meter is provided in each of the first aeration tank and the third aeration tank, and a 1N H ₂ SO ₄ aqueous solution is automatically added to each aeration tank when the measured value of the pH meter exceeds 8. The process was continued.
As a result, the TOC of the treated water became 5 mg / L or less after 3 days, and the ammoniacal nitrogen concentration of the treated water became 1 mg / L or less after one week.
Therefore, the load was tripled. As a result, after 5 days from the increase in load, the treated water TOC was stabilized at 5 mg / L or less and the treated water ammonia nitrogen concentration was 1 mg / L or less, and then the treatment did not deteriorate.

[Example 2]
A pH meter and a 1N NaOH aqueous solution or a 1N H ₂ SO ₄ aqueous solution are added to a 9 L aeration tank (one tank) so that the measured value of the pH meter is 7.0 to 8.5 in conjunction with the pH meter. After installing chemical injection equipment and adding 20% by volume of 10mm square polyurethane sponge carrier to the aeration tank, and adding a small amount of septic tank activated sludge in other places, the same load of raw water of the same quality as in Example 1 (load increase) The water was passed at the later load.
As a result, the treated water TOC became 3 to 5 mg / L after one week. Further, nitrification was completed after 2 weeks, and the ammoniacal nitrogen concentration of the treated water was about 1 mg / L.

Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention.
This application is based on a Japanese patent application filed on July 22, 2011 (Japanese Patent Application No. 2011-161104), which is incorporated by reference in its entirety.

Claims

In a method for biological treatment by introducing an amine-containing organic wastewater from an ultrapure water recovery system into a biological treatment tank, an acid is added to the biological treatment tank based on the pH value of the liquid in the biological treatment tank. A biological treatment method for amine-containing wastewater.
2. The amine-containing wastewater according to claim 1, wherein the biological treatment tank has a structure in which the liquid in the tank is completely mixed, and the amine-containing wastewater is continuously introduced into the biological treatment tank. Biological treatment methods.
The biological treatment method for amine-containing wastewater according to claim 1 or 2, wherein an acid is added to the biological treatment tank so that the pH value is 8.5 or less.
The biological treatment method for amine-containing wastewater according to claim 3, wherein an alkali is added when the pH value is less than 7.
In the device for biological treatment of amine-containing organic wastewater from the ultrapure water recovery system,
A biological treatment tank into which the amine-containing wastewater is introduced;
A pH meter for measuring the pH of the liquid in the biological treatment tank;
A biological treatment apparatus for amine-containing wastewater, characterized by comprising acid addition means for adding an acid to the biological treatment tank based on the measured value of the pH meter.
6. The amine-containing tank according to claim 5, wherein the biological treatment tank has a structure in which the liquid in the tank is completely mixed, and the amine-containing wastewater is continuously introduced into the biological treatment tank. Wastewater biological treatment equipment.
The biological treatment apparatus for amine-containing wastewater according to claim 5 or 6, wherein an acid is added by the acid addition means so that the measured value of the pH meter is 8.5 or less.
The biological treatment apparatus for amine-containing wastewater according to claim 6, comprising means for adding an alkali when the pH value is less than 7.