JPS63291692A - Treatment of waste water containing high concentration tmah - Google Patents

Abstract

PURPOSE:To decompose TMAH efficiently by treating waste water containing tetramethylammonium hydroxide (TMAH) of high concentration with the help of a device provided with fillers with aerobic microbes permitted to grow on their surface in a tank. CONSTITUTION:TMAH of waste water containing TMAH of high concentration is biologically decomposed in a tank containing fillers with aerobic microbes allowed to grow on their surface and an immersion filter bed biological treatment device provided in the tank, with the pH value of waste water maintained to 5.0-7.5. Application of this method allows the concentration of sludge in the tank, especially the concentration of TMAH decomposition bacteria to be maintained at a higher level than a conventional flotation activated sludge method. Subsequently, a TMAH load can be increased 3-5 times that of the conventional method. Further, the subject method allows direct treatment of waste water of high concentration such as 20,000-30,000mg/l of TMAH concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is directed to the use of refractory tetramethylammonium hydroxide (hereinafter abbreviated as TMA), which is used as a remover for printed circuit boards in semiconductor manufacturing factories, for example.
For example, 20°000 to 30,000 leaps/l
The present invention relates to a method for biologically and efficiently oxidizing and decomposing TMAR by treating wastewater containing a high concentration of TMAR using a submerged filter biological treatment device.

<Prior art> TMAH ((CH3)4N・OH) is an alkaline stripping agent that is comparable to choline stripping agents and has very excellent effects, and has recently been used in semiconductor manufacturing factories and other places for printing. Widely used as a substrate stripper. In the process of peeling off the printed board, a silicon wafer (printed board) on which a circuit was optically printed in the previous process is immersed in a concentrated TMAH aqueous solution (TMAH concentration of about 3%) and unnecessary parts are peeled off. It is a process. That is, the printed substrate is first immersed in a concentrated TMAH aqueous solution tank, and then taken out from the tank and washed with a surfactant aqueous solution, ultrapure water, etc. to remove TMAH and other impurities that have adhered to the printed substrate. is removed and then sent to the next process. If the peeling performance of the TMAH aqueous solution in the TMAH aqueous solution tank deteriorates after processing a predetermined amount of printed substrates, a part of it should be extracted and replaced with new solution, or the entire amount should be discarded and a new one should be replaced. Replace with liquid. Therefore, from the stripping process, there are two types of wastewater: cleaning wastewater containing low concentration TMAH, which is continuously discharged in the cleaning operation, and used concentrated TMAH wastewater, which is intermittently discharged from the TMAH aqueous solution tank. Wastewater is discharged.

The TMAH is a strongly alkaline substance with strong toxicity, and it is environmentally unfavorable to discharge the wastewater containing TMAR as it is. However, TM
AH is a chemically very stable substance, and it is not decomposed at all even when treated with strong oxidizing agents such as chlorine, hydrogen peroxide, ozone, and ultraviolet light, or in combination with these, and it is not degraded by activated carbon. It is a substance that is very difficult to treat and cannot be adsorbed. At present, proposed methods for treating TMAH-containing wastewater include adsorption using ion exchange resins, concentration using reverse osmosis membranes, and biological treatment using floating activated sludge. The adsorption method and the concentration method using a reverse osmosis membrane do not decompose TMAH into harmless substances, but simply concentrate them, so the problem remains as to how to treat the concentrated solution, which is not practical. Therefore, at present, the floating activated sludge method using aerobic microorganisms can be said to be the most practical method for treating TMAH-containing wastewater.

<Problems to be solved by the invention> However, although TMAH is a biologically treatable substance, it is extremely difficult to decompose biologically. is, T
Bacteria that specifically degrade MAH (hereinafter referred to as TMAH-degrading bacteria) require a long period of 1 to 2 months to acclimatize, and in addition, for example, 0.1 kg TMAH/n The TMA H concentration that can be treated by the floating activated sludge method is as follows:
However, in order to perform stable processing, it was necessary to lower the TMA H concentration to about 200 μ/l or less. Of the wastewater discharged from the process, wastewater with a low concentration of TMAH, such as washing wastewater, can be treated, but T
20,000~ discharged when renewing MAH aqueous solution tank
When treating wastewater with a high TMAHfM concentration of 30,000 μ/l, there is a problem that a large amount of dilution water and large-capacity treatment equipment are required. Currently, waste disposal is outsourced to waste disposal companies at a reasonable cost.

Furthermore, even when treatment is carried out using the floating activated sludge method, the TMAR load cannot be treated unless it is extremely low as mentioned above, and therefore the growth rate of sludge, especially the growth rate of TMAH-degrading bacteria, is slow, resulting in , outflow of the decomposing bacteria from the aeration tank (
Washout) is also severe, making it impossible to maintain a high sludge concentration in the tank, especially the concentration of TMAH-degrading bacteria.

Therefore, it is difficult to stably treat TMAH-containing wastewater, and there are also problems in that a large amount of other organic matter must be added as a supplementary nutrient source in order to maintain a high sludge concentration in the tank.

The present invention has been made in view of the above-mentioned problems in the treatment of TMAH-containing wastewater discharged from the peeling process of printed circuit boards in semiconductor manufacturing factories, etc., and in particular, treatment has traditionally been outsourced at a high cost. The purpose of the present invention is to provide a method for biologically and efficiently oxidizing and decomposing wastewater containing high concentration TMAH.

Means for Solving the Problems> The present invention is an immersed filter biological system in which wastewater containing high concentration of TMAH is filled in a tank with a filling material on which aerobic microorganisms are grown. It is characterized by biologically treating the water in the tank under conditions of pH 5.0 to 7.5 using a biological treatment device.

Submerged filter bed method biological treatment device (hereinafter referred to as
In a submerged filter bed device, a tank is filled with a filler such as artificial stone, gravel, crushed stone, Raschig ring, or inorganic filler such as activated carbon, and the water to be treated containing organic matter is poured from the top or bottom of the filler layer. On the other hand, oxygen-containing gas such as air is supplied from the bottom of the filler layer, and organic matter in the water to be treated is biologically decomposed and removed by the action of aerobic microorganisms grown on the filler layer. This is a conventionally known method. In addition,
The filler used may either float or settle in the water to be treated.

For example, water to be treated and air for aeration are supplied from the bottom of a submerged filter bed device, which is made by filling a tank with filler such as gravel that settles in water, and overflow is performed from the top of the tank. The case of treating high concentration TMAH-containing wastewater using an upflow type submerged filter device of the water extraction type will be described in detail below.

As mentioned above, TMAH is a strongly alkaline substance, so for example, used high-concentration TMAH aqueous solution (high-concentration TMAR
Containing wastewater, TMAH concentration approximately 20,000 to 30,000
■/N) exhibits strong alkalinity with a pH of 13. Therefore, when the wastewater is treated with a submerged filter apparatus, an acid is first added to the wastewater to neutralize it. In addition, since there are almost no organic substances other than TMAH in the wastewater,
In order to stabilize the treatment, organic substances such as meat extract, peptone, glucose, corn steep liquor are added to the wastewater as supplementary nutritional sources.

However, as shown in Examples below, the amount added may be smaller than in the case of treatment by the conventional floating activated sludge method.

In addition, in the conventional floating activated sludge method, the high concentration TMA
R-containing wastewater cannot be treated directly, and as mentioned above, it has been treated by diluting it so that the TMA H concentration is 200 mg/l or less, but in the present invention, TMA
Since it is possible to directly process high-concentration materials with a H concentration of 2,000 to 30°,000/l, as mentioned above, the TMA HtH degree is 20,000 to 30,000/l.
/l of wastewater can be treated directly without dilution.

Highly concentrated TMAH-containing wastewater that has been neutralized and supplemented with a supplementary nutrient source is supplied from the bottom of a filler layer made of a filler on which TMAH-degrading bacteria have grown on the surface through acclimatization,
On the other hand, aeration is also performed by supplying air from the lower part of the layer. The supplied wastewater containing high concentration TMAR is oxidized and decomposed by the action of aerobic microorganisms, mainly TMAH-degrading bacteria, while passing through the packing material layer, and TMAH in the wastewater is converted into NH
.

-N, or further oxidized to No3-N, N02-
Changes to N. At this time, in the present invention, unlike the conventional floating activated sludge method, aerobic microorganisms mainly consisting of TMAH-degrading bacteria are adhered to the surface of the filler, so T
There is almost no outflow of MAH-degrading bacteria, and TMAH-degrading bacteria can be retained at a high concentration on the surface of the filler. Therefore, the tank as a whole can hold TMAH-degrading bacteria at a higher concentration compared to conventional floating types, and therefore the T
It is possible to increase the MAH load by 3 to 5 times that of the conventional method.

In addition, the present inventors adjusted the pH of the water in the tank to 5.0 during treatment.
If the pH of the water in the tank is adjusted to the pH range of 0 to 7.5, that is, neutral to slightly acidic, the treatment will be performed well, and the pH of the water in the tank will be 5.0 to 7.
．． It has been found that processing performance deteriorates when the value is outside the range of 5. This will be explained in the examples described later. The pH of the water in the tank is adjusted using TMA supplied to the immersion filter device.
This can be done by controlling the amount of acid added during neutralization of H-containing wastewater.

The treated water in which TMAH has been decomposed as described above is discharged from the upper part of the immersion filter device to the outside of the tank by an overflow method. The treated water may be subjected to post-treatments such as nitrification and denitrification as necessary, and then released.

<Effects> As explained above, in the present invention, high concentration TMAH-containing wastewater is treated using a submerged filter bed device in which the tank is filled with a filler for microbial adhesion, so that the sludge concentration in the tank, especially The concentration of TMAH-degrading bacteria can be maintained higher than in the conventional floating activated sludge method, and the TMAH load can be increased 3 to 5 times as much as in the conventional method. Therefore, the device capacity can be made compact to 173 to 115 of the conventional method.

In addition, the method of the present invention has a TMA H concentration of 2°000, which was difficult to process without dilution in the conventional method.
Since it is possible to directly treat wastewater with a high concentration of ~30,000 μ/l, the amount of dilution water can be significantly reduced compared to conventional methods, and in some cases, it is possible to completely eliminate the need for dilution water. has advantages.

Furthermore, the treatment of the high concentration TMA H-containing wastewater no longer needs to be outsourced at a high cost as in the past, and the amount of organic matter added as a supplementary nutrient source is also shown in the examples below. As compared to the conventional method, it requires less, so it is also superior in terms of cost reduction.

It goes without saying that even when the present invention is applied to wastewater with a low TMAR concentration, such as the above-mentioned cleaning wastewater, excellent effects are exhibited.

<Examples> Examples will be described below to further clarify the effects of the present invention.

A submerged filter bed device was used in which 52 approximately spherical artificial stones with a particle size of 5 to 20 m and a specific gravity of 1.2 to 1.3 were packed into an acrylic column with an inner diameter of 8I1 m (packed bed approximately 1 m). , high-concentration TMAH-containing wastewater discharged from the printed circuit board stripping process of a semiconductor manufacturing factory (TMAH concentration 21.0
Table 1 shows the results of diluting 00 μl/l, pH=12.8) to an appropriate concentration or directly treating it without diluting it.

During the treatment, hydrochloric acid was added as a neutralizing agent, meat extract was added as a supplementary organic nutritional source, and N was added as a phosphorus source.
The required amount of az HP O4 was added. Also, TMAH
The concentration was determined by ion chromatography.

For comparison, the above wastewater was diluted to an appropriate concentration using a floating activated sludge system (composite tank with aeration section and settling section integrated, aeration section capacity: 51), and the results are also shown in Table 1. Shown below.

As shown in Comparative Example-1, Comparative Example-3, and Comparative Example-4 in Table 1, in the conventional method, the TMAH load was approximately 0.1 kg.
Good processing can be achieved with the /ryr/grain level, but TMA
In Comparative Example 2 in which the H load was increased to 0.24 kg/day, the TMAH removal performance deteriorated. Regarding the TMAH concentration in the raw water to be treated, Comparative Example-1 and Comparative Example-
3. Comparative Example-4 was processed without any problem, but T M
A H>74 degrees is 2.0OOff1r/j! In Comparative Example-5, the TMAH load was 0.09 kg/rr.
Despite the low load of one day and the pH of the treated water (in other words, the pH of the tank water) being within the appropriate range, TMA
Deterioration of H removal performance is observed.

On the other hand, in the embodiment of the present invention, the TMAH concentration ranged from 500 to 21.000 (undiluted) ■/l, and the TMAH load ranged from 0.3 to 0,4 kg/l.
n?・It was possible to process a high load of 1 day.

(Example-1, Example-2, Example-4, Example-6, and Example-7) In addition, in the present invention, the pH of the treated water is 5.0 to 7.5.
If the pH of the treated water is within this range, the treatment is good, but Example 3 where the pH of the treated water deviates from this range (treated water pH 4,
5), Example-5 (treated water pH 8°0) and Example-
8 (treated water pH 4, 6), both TMA
H removal performance has deteriorated.

Furthermore, regarding the amount of meat extract added as a supplementary organic nutrient source, in the present invention, as shown in Example 7, raw water T
Even when the MAH concentration is as high as 21,000 μ/1, good treatment can be achieved with the addition amount of meat extract of 500 μ/2, whereas in the conventional method, for example, as shown in Comparative Example 4, the raw water TMAH concentration is The meat extract must be diluted to 1.500 μ/l and 500 μ/l of meat extract must be added to the diluted raw water. Therefore, the amount added is sufficient to treat a unit weight of TMAH. Become.

Procedural amendment (voluntary) August 15, 1988 Director General of the Japan Patent Office Yoshi 1) Moon Takeshi 1, Indication of the case 1988 Patent Application No. 123896 2, Name of the invention Method for treating wastewater containing high concentration TMAH 3, Relationship with the case of the person making the amendment Patent applicant address 5-5-16 Hongo, Bunkyo-ku, Tokyo Name
(440) Organo Co., Ltd. Representative
1) Rong Ke 4, Agent Address: 113, 812-5151 5. Please correct the following matters in the specification subject to amendment.

1. In the 9th line from the bottom of the 5th line, change the phrase ``because it's tough'' to ``
It’s intense,” he corrected.

2. In the 8th line from the bottom of the 6th line, "Inorganic fillers such as activated carbon" should be corrected to "Inorganic fillers such as activated carbon, or plastic fillers such as nets, honeycomb tubes, etc." .

that's all

Claims (1)

[Claims] Tetramethylammonium hydroxide (TMA
Wastewater containing a high concentration of H) is treated by using a submerged filter biological treatment device in which a tank is filled with a filler on which aerobic microorganisms have grown, and the pH of the water in the tank is adjusted. 5.0-7.5
A method for treating wastewater containing high concentration TMAH, characterized by biologically treating it under the following conditions.