KR100648494B1 - TMAH Method for Treating Waste Water Containing Tetramethyl Ammonium Hydroxide - Google Patents

Abstract

A method for treating wastewater is provided to be able to efficiently remove tetramethyl ammonium hydroxide from the wastewater through membrane bio-reactor process using Acinetobacter sp. IBN-H6. The method for treating wastewater comprising tetramethyl ammonium hydroxide is characterized in that it uses Acinetobacter sp. IBN-H6(deposition number : KCTC 10809BP) for the wastewater treatment. For the treatment, at least one strain selected from the group consisting of Kluvermyces delphenisis IBN-H1(deposition number : KCTC 0834BP), Bacillus cereus IBN-H4(deposition number : KCTC 0835BP) and Acinetobacter sp. IBN-H7(deposition number : KCTC 0836BP) is further added thereto.

Description

Method for Treating Waste Water Containing Tetramethyl Ammonium Hydroxide

1 is a schematic diagram of an MBR wastewater treatment apparatus according to the present invention.

Figure 2 is a schematic diagram of a conventional sedimentation tank wastewater treatment apparatus according to the prior art.

Figure 3 is a graph showing the survival density by TMAH concentration of the strains according to the present invention.

4 is a schematic diagram of IBN-H6 according to the present invention.

5 is a graph showing the growth curve according to the culture temperature of IBN-H6 according to the present invention.

Figure 6 is a graph showing the growth curve according to the culture pH of IBN-H6 by the present invention.

Figure 7 is a graph showing the concentration of the strain in MBR wastewater treatment according to the present invention.

The present invention relates to a novel strain for the decomposition of tetramethyl ammonium hydroxide and to a wastewater treatment method using an electrical strain. More specifically, the present invention relates to a wastewater treatment method using novel strains and electric strains, which are contained in a large amount in the waste liquid of the optoelectronic industry, and efficiently decompose TMAH which is difficult to decompose and toxic.

The opto-electronics industry is a high-tech industry that is developing very rapidly in recent years worldwide. The demand for products in the optoelectronics industry is soaring, many countries are spurring product development. Many semiconductor industries include processes for (1) arrays, (2) color filters, and (3) liquid crystals, which use large amounts of organic solvents as developer, cleaning solution, and etchant. As a result, a large amount of waste water is generated. These wastewaters are characterized by a very high content of tetramethylammonium hydroxide (TMAH) in addition to organic solvents such as dimethyl sulfoxide (DMSO) or isopropyl alcohol (IPA).

Because TMAH is a biodegradable and highly toxic substance (toxicity LC 50 = 460 PPM), there is a severe fluctuation in the biological oxygen demand (BOD) of wastewater treatment plants in semiconductor manufacturing plants. Therefore, the removal of TMAH from industrial wastewater is a very important issue for environmental protection.

Currently, the treatment of TMAH in the wastewater is concentrated waste method in which the wastewater is concentrated and discarded by ion exchange resin column, UF (ultrafiltration) or RO (reverse osmosis), or by burning the concentrated TMAH. The degree of supercritical treatment to remove is known. However, this conventional purification method has a serious drawback that not only goes through very complicated steps but also causes secondary pollution problems due to concentration or combustion. Accordingly, there is a need for a more economical and efficient method for biological treatment of TMAH in response to the increasing demand for environmental protection.

In the wastewater treatment, the MBR process (Fig. 1) can completely remove the suspended solids due to the separation characteristics of the membrane, so that stable treatment is possible regardless of the sedimentation property of the sludge. As the concentration of microorganisms can be accumulated in a short time, a large amount of water treatment, that is, a numerical processing time (HRT) can be maximized even in a small space, so the volume of the process is also reduced, making the process compact. Among the advantages of MBR, the most important thing is that it can be operated stably. It can maximize the sludge residence time (SRT), which can greatly reduce not only biological treatment time but also treatment efficiency. Therefore, deterioration of sedimentation, inflow of high concentration of toxic substance, change of treatment conditions, etc. It has been spotlighted as a technology that can compensate for various problems of the existing activated sludge process such as being vulnerable to impact load or low treatment efficiency.

The separator used in the environmental field is a barrier capable of separating two phases, i.e., a semipermeable membrane in which only an interface between two fastening phases or a material of an optional type passes through the structure. It can be defined as a semipermeable barrier.

The commercially available precision separators are classified into polymer and inorganic materials, and inorganic materials include ceramic (primarily α-alumina), glass, and carbon. And a sintering method (ceramic film).

Advantages of the double ceramic separator are first, high stability against high temperature, acid, and alkali compared to the polymer membrane. Second, it is possible to manufacture a ceramic film having a more advantageous shape and form than the polymer film. Third, since the mechanical strength is high, there are few micropore changes at high pressure, so normal operation at high pressure is possible. Fourth, the actual service life is about 3 ~ 5 years, which is longer than the organic membrane, and the inorganic material is less contaminated with microorganisms or organic substrates, and the CIP is processed at higher temperature, acid, and alkali than the polymer membrane. Much longer. In addition, it has better permeability than organic membranes and has high stability against toxic substances, organic solutes, contaminants, etc., and thus may be much more useful than polymer membranes in environmental treatment.

The present invention for solving the above problems is an object of the present invention to provide a wastewater treatment method that can efficiently remove TMAH in the wastewater by the MBR process using the above strain.

It is another object of the present invention to provide a novel strain capable of efficiently decomposing and removing TMAH having difficulty in degradability and toxicity.

The present invention for achieving the above object relates to a biological wastewater treatment method using a novel strain and an electric strain that is contained in a large amount in the waste solution of the optoelectronic industry, and efficiently decomposes TMAH having a difficult decomposition and toxicity at room temperature.

The strain according to the present invention was isolated and identified through the following process.

First, after collecting the wastewater of the domestic semiconductor factory as a sample, inoculating the sample into a nutrient-rich medium, firstly multiplying the strains present in the wastewater, selecting 12 strains and naming each of them as IBN-H01 ~ H12 It was. Subsequently, the strains were grown by growing at 30 ° C. in a medium containing TMAH, that is, five strains resistant to TMAH and excellent in TMAH resolution were isolated.

Three strains with excellent TMAH resolution were identified using a biolog system, MIDI and partial sequencing of 16s RNA, and two of the three strains were described in detail in Korean Patent Laid-Open Publication No. 2002-0009060. It was confirmed that the same strain as IBN-H1 and IBN-H7. The other one was identified as a novel strain corresponding to the genus Acinetobacter sp. And was named as IBN-H6 in the genus Acinetobacter sp. On May 24, 2005. Deposited as KCTC 10809BP.

The isolated new strain was found to be capable of growing to an OD value of about 0.2 in a minimum medium containing only TMAH as an essential mineral component and carbon source. In addition, it was possible to grow without significant difference at 30 ℃, it was excellent growth in neutral to weak acid conditions.

Since the strain according to the present invention is not only resistant to TMAH but also can be grown as the only carbon source, the strain can be used for biological treatment of wastewater containing TMAH. At this time, the strain may be used independently, three or more strains described in detail about the TMAH resolution in the Republic of Korea Patent Publication 2002-0009060, IBN-H1, IBN-H4 and IBN-H7 and 2 to 4 mixed culture state Can also be used.

In the TMAH treatment system, a large amount of microorganisms with high preference of microorganisms existing in existing wastewater treatment plants and toxic and organic wastes such as TMAH coexist and must be operated in an absolute carbon source depletion state to decompose TMAH. In the treatment step, it is preferable that the microorganism IBN-H6 alone or the mixed microorganism of IBN-H6 and other microorganisms of the present invention having excellent TMAH resolution is artificially cultured and separated from general wastewater to be treated independently.

The wastewater treatment process can be applied to any process of a known biological treatment process, but the TMAH-treated microorganisms are smaller in size than the microorganisms of a general wastewater treatment plant, maximizing the characteristics and treatment efficiency of the microorganisms and impacting them. Considering the capacity to cope with the load, it is more preferable to use the MBR treatment method. The treatment of TMAH, which is highly biologically toxic as described above, by MBR method does not affect other water treatment processes such as denitrification and dephosphorization, does not require secondary treatment, generates less sludge, and affects TMAH concentration in influent. There is an advantage that does not receive much. In addition, in space efficiency, as shown in Table 1, only about 1/20 ~ 1/38 of space is required compared to the existing equipment. Therefore, according to the treatment method according to the invention it is possible to minimize the required site for the treatment of waste water containing TMAH, it can be cheaper equipment and maintenance costs.

공간효율성은 다음과 같이 계산되며, 본원발명의 경우 각 데이터는 하기 실시예 6의 표 5로부터 얻었다.
공간효율성 m³/kg(TMAH)
= [폐수(m³)/처리되는 TMAH(kg)] ÷ [24(시간)/잔류시간(시간)]

The space efficiency is calculated as follows, in the case of the present invention each data was obtained from Table 5 of Example 6.
Space efficiency m ³ / kg (TMAH)
= [Wastewater (m ³ ) / TMAH (kg) treated] ÷ [24 (hours) / remaining time (hours)]

It is particularly preferable that the membrane in the MBR is a ceramic membrane. Unlike conventional polymer membranes, ceramic membranes can overcome the operational problems due to chemical stability, physical robustness, and the introduction of back pulses to the wastewater and microorganisms.

In addition, it is preferable to use the strain fixed to a predetermined carrier for the continuous use of the strain and easy removal of the strain in the treated water for general biological process applications other than the MBR method. In this case, the carrier may utilize a conventional microorganism fixing material such as alginate and urethane foam.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only to specifically describe the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples.

Example

Example 1 Isolation of Strains Resistant to TMAH

(1) Propagation of Strains Existing in Wastewater in Semiconductor Plants

Wastewater samples such as influent water, aeration water, and return sludge were prepared in the biological and organic treatment and denitrification processes at each semiconductor manufacturing plant in Korea.

After diluting the sample sequentially, plated on nutrient agar plate medium (beef extract 0.3% (DIFCO), peptone 0.5% (DIFCO), agar 1.5% (DIFCO)) rich in carbon source and incubated for 18 hours at 30 ℃ Twelve strains were selected and named for each of IBN-H01 to IBN-H12.

(2) Isolation of strains resistant to TMAH

It was confirmed whether the strains obtained in the growth step to the TMAH resistance.

In a nutritious medium rich in carbon sources (beef extract 0.3% (DIFCO), peptone 0.5% (DIFCO)), the TMAH concentration was prepared to be 0.25%, 0.5%, 1.0%, 1.5%, and 2.0%, respectively. After spreading, shaking was incubated at 30 ° C. for 24 hours at a rate of 250 rpm.

Among them, five mediums (IBN-H01, IBN-H04, IBN-H05, IBN-H06, and IBN-H08) in which the growth of the cells is visually selected are selected, and the nutrient agar plate is selected by the serial dilution method. The total number of bacteria was smeared on the medium and represented as the number of colony forming units (CFU) per ml of culture (FIG. 3).

As can be seen in Figure 3, all five strains of IBN-H01, IBN-H04, IBN-H05, IBN-H06, and IBN-H08 all exhibited strong inhibition against TMAH except for a slight inhibition of survival in the presence of 1.7% or more TMAH. It has a high survival rate of 10 ⁸ to 1.5%. In particular, IBN-H06 shows excellent survival rate even from low TMAH concentration to high concentration range of 2.0%.

Example 2 investigation of TMAH degradation rate of strain selected as TMAH resistant strain

The TMAH degradation rate of the TMAH resistant strains selected in Example 1 was investigated.

Minimum medium containing (NH4) ₂ SO ₄ 3g / L, Trace element (H ₃ BO ₃ 0.3g, CoSO _{4 ·} 7H ₂ O 0.2g, ZnSO ₄ H ₂ O 0.1 g, MnCl ₂ H ₂ O 0.03 g, NaMoO ₄ H ₂ O 0.03 g, NiCl ₂ H ₂ O 0.02 g, CuSO ₄ H ₂ O 0.01 g, FeSO ₄ H ₂ O 20 g, CaCl ₂ H ₂ O 10 g / L) 2 ml / L, MgSO ₄ 7H ₂ O (40%) 2 ml / L, 1M phosphate buffer (pH 7)) was added with 1% TMAH as a carbon source and incubated for 72 hours at 30 ℃.

The BOD of the final culture was measured by a triple test, and showed over 90% BOD removal rate in IBN-H04, IBN-H05 and IBN-H06 strains (Table 2).

Example 3 Identification of Strains with Excellent TMAH Resolution

Three strains IBN-H4, IBN-H5 and IBN-H6 selected in Example 1 and confirmed to have excellent TMAH resolution in Example 2 using BIOLOG test, fatty acid analysis, MIDI and 16S rRNA partial sequencing, etc. The strains were identified.

As a result of the identification, four strains IBN-H04 and IBN-H05 were identified as the same strains as IBN-H1 and IBN-H7 identified in Korean Patent Laid-Open Publication No. 2002-0009060, respectively, and thus detailed data are omitted and IBN-H06 was omitted. Only the identification results for are described in detail.

First, as a result of examining the morphological and biochemical characteristics of the strain IBN-H06 of the present invention, it had catalase activity, and showed a negative response to the Gram staining reaction observed when identifying bacteria (Table 3).

As a result of homology analysis of the 16s RNA partial sequence (SEQ ID NO: 1) of the strain, it was determined to be 94% to 97% homology with the genus Acinetobacter (Table 4).

There are currently 8 species of Acinetobacter, and it is considered a new species because there is no species with a similarity of more than 98%. As described above, the strain IBN-H06 according to the present invention was identified as a novel strain that has not yet been reported, and named as Acinetobacter sp. IBN-H6 (Acinetobacter sp. IBN-H6) on May 24, 2005 The deposit was made with the deposit number KCTC 10809BP to the Biotechnology Research Institute Gene Bank (KCTC), an international depository institution (hereinafter referred to as strain IBN-H06 as IBN-H6). In addition, the microorganisms and other related strains are expressed in a phylogenic tree (FIG. 4) to indicate that they are new strains different from the existing TMAH degradation strains Acinetobacter genus IBN-H7 and Bacillus cyrius IBN-H4. It was.

Example  4: screening Identified  Strain TMAH  Usability

It was confirmed that the strain IBN-H6 strain of the present invention identified above can use TMAH as the only carbon source.

Add 0.5% TMAH as a carbon source to a minimal medium containing minerals essential for the growth of strains (see Example 2), then inoculate the strain and incubate for 72 hours at 30 ° C. It was. The culture medium was diluted sequentially to prepare and spread a plate medium having the same composition as the culture solution components.

It was observed that the strains of the present invention each form colonies on the plate medium, it was confirmed that the strains of the present invention can be grown using TMAH as the only carbon and energy source.

For comparison, it was confirmed the TMAH availability of the strains that are related to the strains according to the present invention.

Instead of the strains of the present invention, Acinetobacter low blood, Acinetobacter calcoaceticus or Acinetobacter genospersis were cultured, respectively, and the presence or absence of TMAH carbon source was investigated.

As a result, all strains having a flexible relationship with the strain according to the present invention did not form colonies, and thus, the strains did not use TMAH as a carbon source.

From this result, IBN-H6, a strain according to the present invention, belonged to the genus Acinetobacter, but it was also confirmed that it is a novel strain that differs in physicochemical properties from conventional strains.

Example 5: Growth Characteristics of Identified Strains

(1) Growth Characteristics According to Culture Temperature

To determine the optimum incubation temperature of the isolated strain, 200 µl of the same component as the medium used in Example 2 was added to a 96-well microplate and shaken at 250 rpm for 25 hours at 25 ° C and 30 ° C. It was. OD values of the strains were measured at 600 nm using a microplate reader (MR5000, Dynatech, U.S.A.) (FIG. 5).

As can be seen in Figure 5, the growth was better than the case of the temperature of 30 ℃ in the total incubation process than the case of 25 ℃, the number of cells (OD value) according to the incubation time at each temperature condition is almost constant 30 ℃ and About 0.2 and 0.15 were shown at 25 degreeC, respectively.

(2) growth characteristics according to pH

In order to determine the optimum culture pH of the isolated strain, 200 µl of the same component as the medium used in Example 3 was added to a 96-well microplate, and the temperature was reduced to 30 ° C, 72 at pH 5, pH 7 and pH 9. Shake culture was performed at 250 rpm for an hour. The OD value of the strain was measured at 600 nm using a microplate reader (MR5000, Dynatech, U.S.A.) (FIG. 6).

As shown in FIG. 6, the OD value was almost 0 at pH 9, but showed an OD of about 0.2 in the pH range of 5 to 7, indicating that it grows well in neutral to slightly acidic conditions.

Example 6 MBR Formulation Process of TMAH Using Strain according to the Present Invention

In the above embodiment, the strain according to the present invention was confirmed that the growth is possible by using TMAH as the only carbon source, the efficiency of the wastewater containing TMAH was treated by MBR formula. In general, since a single strain may have a problem in stability, a mixed strain of IBN-H6, which is a strain according to the present invention, and another strain was used in this example.

(1) High Density Cultivation of Cells for Use in Process

In order to utilize the TMAH-containing wastewater treatment, the strain of IBN-H6, the strain of the present invention, and the three strains IBN-H1, 4, and 7 described in Korean Patent Laid-Open Publication No. 2002-0009060 were each cultured at high density.

High concentration medium (20g / L glucose, 15g / L yeast extract, MgSO ₄ ㆍ 7H ₂ O 2g / L, KH ₂ PO ₄ 5g / L, (NH ₄ ) 2SO ₄ 4g / L, pH 7.0 (HCl) ) Inoculated strains according to the present invention into a 500L fermenter containing 350L and stirred culture at 30 ℃, followed by incubation for 24 to 48 hours by adding a carbon source of 10g / L equivalent glucose 12 hours after inoculation. .

1200 L of strain IBN-H6 and IBN-H1,4,7 strain culture medium of the present invention in which the OD was incubated at a high concentration of 40 or more was seeded in 12 ton of TMAH wastewater.

(2) Applied to the TMAH wastewater treatment process of the invention strain

The operating conditions of the fermenter were maintained at a culture temperature of 25-35 ° C., 0.5vvm of inflow air, and the TMAH concentration of the incoming wastewater was 3-5 g / L, adjusted to pH 6.5-7.5 using sulfuric acid. In order to stabilize the cells, 1/10 concentration of culture medium and 11 tons of TMAH wastewater were introduced for 3 days every 24 hours, and TMAH 5g / L, (NH ₄ ) 2.SO ₄ 3 g / L, yeast extract 0.3g / L, MgSO ₄ 7H ₂ O was further added at a concentration of 0.3g / L. After stabilizing the cells in the reactor, the operating capacity was 14-16 tons, pH 6.5-7.5, and treatment temperature 25-35 ℃. MBR type continuous treatment was performed to recover the cells to the fermenter through membrane separation of the treated water discharged while flowing in and out of the wastewater containing 3 to 5 g / L concentration of TMAH from 4 days after straining.

The concentration of microorganisms in the reactor according to time after continuous operation was shown in FIG. 7 by measuring the dry cell mass and the total number of viable cells. As can be seen in Figure 7, the cell concentration was continuously increased until the 5th day of continuous operation and after the MLSS concentration was activated to about 3000ppm was carried out sludge withdrawal to 5 ~ 20 kg / L level. The average numerical residence time was 7-8 hours and the wastewater treatment amount was 50m ³ / day. The pH of the introduced wastewater was 12 to 13, and the pH of the wastewater was adjusted to 9.5 to 10.5 in a pH control tank. TMAH treatment efficiency was treated more than 90% from 3 days after the start of continuous operation, MLSS in the fermenter was maintained at 3,000 ~ 15,000ppm after 15 days of continuous operation, and the transmembrane pressure difference (TMP) was about 0.7 bar in the membrane separation process. Detailed operating conditions in continuous operation are shown in Table 5.

As shown in FIG. 5, the concentration of the strain in the fermenter according to the wastewater treatment was not significantly affected by the TMAH inflow, and remained stable. Even after three months of continuous operation, the concentration of the strain remained stable without significant change. The average was over 90%.

The present invention is mainly used when etching the surface of the silicon in the semiconductor manufacturing process, a wastewater treatment method containing a TMAH using a novel strain and an electric strain to decompose tetramethylammonium hydroxide which is difficult to decompose and toxic to provide.

Wastewater treatment method according to the present invention provides an eco-friendly water treatment method of maximizing TMAH treatment efficiency by introducing MBR that can maintain microbial concentration and high concentration of microorganisms using hardly degradable TMAH as the only carbon source.

 In addition, separate treatment of TMAH, which has low installation and maintenance costs, very high space efficiency, and high biological toxicity, does not affect other water treatment processes. In addition, it is not affected by TMAH concentration in influent, does not require secondary treatment, and has a small amount of slush generation, so it will be widely used in industrial sites as an environmentally friendly wastewater treatment method.

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Claims (10)

delete A microbiological water treatment method of wastewater containing tetramethyl ammonium hydroxide (TMAH) characterized by using Acinetobacter sp. IBN-H6 ( Acinetobacter sp. IBN-H6; KCTC 10809BP). The method of claim 2, Kluvermyces delphenisis IBN-H1; KCTC 0834BP), Bacillus cereus IBN-H4 ( Bacillus cereus IBN-H4; KCTC 0835BP) or IBN-H7 (Acinetobacter sp. -H7; KCTC 0836BP) Microbiological water treatment method of the waste water containing TMAH, characterized in that any one or more strains of strains are added. delete The method of claim 2 or 3, Microbiological water treatment method of TMAH-containing wastewater, characterized in that the strain is immobilized. delete The method of claim 2 or 3, Microbiological water treatment method for wastewater containing TMAH, characterized in that the treatment in aerobic conditions. The method of claim 2 or 3, A microbiological water treatment method for wastewater containing TMAH, characterized by a continuous treatment method for recovering and circulating microbial cells using a ceramic membrane having chemical resistance to TMAH. The method of claim 8, TMAH of influent wastewater is 1-7 g / L, Adjust the pH of the influent wastewater to the range 5.0-8.0, Microbiological water treatment method of TMAH-containing wastewater, characterized in that the continuous operation at 20 ~ 40 ℃ condition of residence time 6-10 hours. The method of claim 8, Microbiological treatment method of wastewater, characterized by maintaining the space efficiency for TMAH treatment at 0.074 ~ 0.123 m ³ / kg (TMAH).

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