KR20140111756A

KR20140111756A - Optimum process for nitrogen removal in semiconductor rinsing waste water

Info

Publication number: KR20140111756A
Application number: KR1020130026033A
Authority: KR
Inventors: 정의택
Original assignee: 미래와환경이엔지주식회사
Priority date: 2013-03-12
Filing date: 2013-03-12
Publication date: 2014-09-22

Abstract

The present invention relates to an optimal process for removing nitrogen in semiconductor wastewater, and more particularly, to a process for removing NH ₃ OH, H ₂ O ₂ , and Citric Acid.
SC-1 (Standard Clean 1) wastewater is a hydrophilic material mixed at a ratio of DI (deionized water): NH ₄ OH: H ₂ O ₂ = 13: 1: 1. Double NH ₄ OH is to the essential removal of the TN as absolute causative agent of _{^{_{TN NH 4 + → NH 3 →}}} NO 3 _ → NO 2 _, NO - is removed through the process of → N _2, the invention is in cleaning semiconductor Considering that the removal amount of TN can be controlled by controlling the MLSS (mixed liquer suspended solid) concentration in the aeration tank in the treatment of nitrogen removal in the wastewater, the inflow amount of the semiconductor cleaning wastewater, which is a parameter of the MLSS concentration, SS concentration, SS concentration of influent water, and return sludge amount, and to maintain optimal MLSS concentration and to develop optimal process for nitrogen removal in semiconductor cleaning wastewater.

Description

[0001] OPTIMUM PROCESS FOR NITROGEN REMOVAL IN SEMICONDUCTOR RINSING WASTE WATER [0002]

The invention of NH ₄ main components of the present invention relates to the optimal process for the high concentration of nitrogen removed in the semiconductor cleaning waste water, the SC-1 (Standard Clean 1) More specifically, the semiconductor cleaning, processing the substance in the waste water-based wastewater OH, H ₂ O ₂ , and Citric Acid.

Nitrogen compounds in wastewater are essential nutrients in addition to phosphorus, but if they are not adequately treated and excessively discharged into the water system, eutrophication is caused, and water pollution caused by the growth of algae is increased, which is costly to purify . Eutrophication waters may cause the clogging of the filter paper and the taste of tap water to be reduced during the treatment of the water, causing odors to be lost, and the water-based role to be lost.

SC-1 (Standard Clean 1) semiconductor cleaning wastewater is chemically separable because it is a hydrophilic material mixed at a ratio of DI (deionized water): NH ₄ OH: H ₂ O ₂ = 13: 1: 1. Double NH ₄ OH is an absolute causative agent of TN, to a fundamental elimination of the _{^{_{TN NH 4 + → NH 3 →}}} NO 3 _ → NO 2 _, NO - is removed through the process of → N _2, a conventional main processing The method is as follows.

1) Physicochemical removal method

(1) Break point The chlorination process is a process in which ammonia nitrogen of wastewater is removed by nitrogen gas through chemical reaction with chlorine. When organic nitrogen and nitrate oxygen are contained in wastewater, the removal effect is small.

(2) Stripping ammonia

Raise the pH of the waste water with at least 10-11, modified by the hand of NH ₄ ⁺ NH ₃ to molecular form, in a manner that removed by contacting with air to Air Stripping, pH 7 in the presence of water as NH ₄ ^+, but Since it exists in ammonia state at pH 11 or higher, the pH of wastewater is elevated to above 11, and it is removed by ammonia gas in contact with air in a degassing tower. In this process, removal efficiency of organic nitrogen, nitrite nitrogen and nitrate nitrogen is low.

(3) ion exchange method

It is a method of removing ammonium ions by passing a column having a strong characteristic of selectively substituting ammonium salts in the waste water and wastewater. The removal efficiency of ammonia is as high as 90% or more, but organic nitrogen, nitrite nitrogen, nitrate nitrogen and the like are not treated.

2) Biological removal method

The principle of biological nitrogen removal is divided into two categories: first, nitrogen removal method by microbial assimilation; second, ammonia and organic nitrogen in influent and wastewater are converted into nitrate nitrogen and nitrite nitrogen under certain conditions A nitrification process, and a denitrification process, which is a process of removing nitrogen compounds by reducing nitric acid and nitrogen through nitrification in a treatment system and discharging the nitrogen gas into the atmosphere.

(1) Nitrogen removal by assimilation of microorganisms

(2) Nitrification

Nitrification is a process in which ammonia is oxidized into nitric acid by nitrite and nitrite by nitrite and nitrite in an aerobic condition.

[Energy response 1 step]

[Energy Reaction Phase 2]

(3) Denitrification and digestion

When microorganisms decompose organic matter, it is denitrification that nitric acid changes into nitrogen gas while nitric acid is used as a final electron acceptor instead of oxygen. Therefore, it is reported that the denitrification proceeds in the absence of oxygen, but the denitrification proceeds even in the presence of oxygen in a weakly acidic state. Since denitrification is a decomposition reaction of organic matter, a carbon source is required, and methanol is mainly used as a carbon source. The reaction is as follows.

[Energy response 1 step]

[Energy Reaction Phase 2]

3) Biological nitrogen removal process

The biological nitrogen removal process is a process of denitrifying nitrified wastewater. In order to remove nitrogen in the wastewater, both nitrification and denitrification are required. The processes for these reactions are Single Sludge Process, Dual Sludge Process, Triple Sludge Process and 4-stage Bardenpho Process.

(1) Singe - sludge Process

Since there is one settling tank and nitrifying bacteria and denitrifying bacteria coexist, the baffle is used to prevent the denitrifying bacteria from being exposed to oxygen, or the reaction proceeds in the different reaction tank. The characteristic of this process is that it does not supply the carbon source (methanol) needed for the denitrification reaction and uses the carbon source that is generated when the microorganism is decomposed or existing.

- Ludzack and Ettinger process

(2) Dual - Sludge Process

In the first step, organic matter removal and nitrification are promoted. In the first step, most of the carbon source is removed from the first step. Therefore, methanol should be added as a carbon source for denitrification.

- Rotating Biological Contactor (RBC)

(3) Triple Sludge Process

In this process, in order to reduce the influence of the organic substances on the nitrification reaction, the reaction tank for removing the organic substances and the nitrification tank are separated from each other, so that the maximum efficiency can be obtained Process stability is high.

(4) Four - Stage Bardenpho Process

The denitrification reaction proceeds by using the carbon source generated when the waste water and the return sludge are introduced into the first reactor (Anoxic) and the carbon source or microorganisms in the wastewater are decomposed. Ammonia passing through the first reactor is oxidized via nitrification in the second reactor, and the nitrogen gas produced in the first reactor is removed there. Again, the residual nitrogen source is removed via Anoxic / Aerobic.

(5) Oxidation ditch Process

As a loop type reaction tank that promotes nitrification and denitrification in one reactor, wastewater flows into the Anoxic region, and organic matter and nitrogen source are removed through the aerobic region. Since this process causes a denitrification reaction once, the nitrogen removal rate is lower than the Bardenpho Process.

Such a nitrogen removal process is described in Japanese Patent Application No. 2010-290588

Method and drainage

And Korean Patent Application No. 1020030095157 (microorganism activator for nitrogen removal of refractory wastewater and method for producing the same).

Application No. (1020060117388) / Nitrification culture method for improving nitrogen removal efficiency (Concentrating culture methods of nirifying bacteria for improving nitrogen removal.) Application No. (1019990055224) / Nitrogen-removing microorganism (ammonia nitrogen → nitrate nitrogen) immobilization method (THE METHOD FOR IMMOBILIZING BACTERIA INNITRIFICATION) Application No. (1020030095157) / Microorganism Activator for Removing Nitrogen from Nitrogen-Deficient Wastewater and Method for Producing the Same (Microorganism Activator for Nitrogen Removal from Non-degrable Waste-Water and Method for Preparing the Microorganism Activator)

Methane Production and Nitrogen Removal from Swine Wastewater in Combined Two Phase Anaerobic Digestion Process (Chungbuk National University, Biological Nitrogen Removal (Pohang University of Science)

The present invention relates to an optimal process for removing nitrogen in semiconductor wastewater, and more particularly, to a process for removing NH ₃ OH, H ₂ O ₂ , and Citric Acid.

More particularly, the present invention relates to a more efficient method of biologically treating nitrogen in various organic semiconductor wastewater. In particular, in the treatment of semiconductor wastewater containing a large amount of nitrogen, which is one of eutrophication-inducing substances, by a biological treatment method, mixed liquer suspended solid can be effectively removed by a method of grasping and controlling the wastewater inflow amount Q, the sludge return amount Q _r , and the return sludge SS concentration R, which are potential factors affecting the TN removal efficiency, To develop the optimal process to be able.

The present invention can control the removal amount of TN by controlling the concentration of MLSS (mixed liquer suspended solid) in the aeration tank in removing nitrogen in the semiconductor cleaning wastewater as described above, Development of a process for efficiently removing nitrogen in the semiconductor cleaning wastewater by continuously controlling the optimum MLSS concentration by determining a controllable factor among the inflow amount of the washing wastewater, the SS concentration of the return sludge, the SS concentration of the influent water, and the sludge return amount I want to.

In order to determine the latent factors of the mixed liquer suspended solids (MLSS) as a parameter of the process for nitrogen removal, we used the following equation (1) as a means for deriving the optimum MLSS concentration, And the amount of surplus activated sludge drained was determined.

Q is the influent flow (m ³ / d), Q is the flow rate (m ³ / d), M is the concentration of the MLSS in the aeration tank (mg / L), R is the concentration of SS in the return sludge _r : Return sludge amount (m ³ / d)]

[Q _r: excess sludge withdrawal amount ^{(m 3 / d), V} : aeration tank volume (m ^3), M _A: present in the aeration tank MLSS concentration (mg / L), M _L: an aeration tank to be managed MLSS concentration (mg / L), R: SS concentration of returned sludge (mg / L)]

In order to solve the problem inherently inherent in the removal of nitrogen in semiconductor cleaning wastewater, it has been invented as a result of repeating experiments after examining various conventional wastewater treatment methods.

Hereinafter, the structure of the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. Further, the present invention is not limited to the semiconductor wastewater, but is not limited thereto.

According to the above-described process development, by appropriately managing the MLSS concentration, which is difficult to control in the conventional biological treatment method, the wastewater inflow amount, the return sludge discharge amount, and the return sludge SS concentration, It can be used.

In addition, it will contribute to the management performance by reducing the wastewater treatment cost by efficiently operating the wastewater treatment plant, and will contribute to the improvement of the image as an environmentally friendly company through continuous environmental improvement activities.

[Figure 1] Optimal process diagram for removing high concentration TN
[Fig. 2] Process chart for removing TN
[Fig. 3] TN removal rate according to parameters
[Fig. 4] TN removal ratio according to MLSS
5] Denitrification change due to stepwise load operation (range of 50.0 ppm)
6 is a graph showing changes in denitrification (in the range of 100.0 ppm)
7 is a graph showing changes in denitrification (in the range of 150.0 ppm)
8 is a graph showing changes in denitrification (200.0 ppm range)
9] Denitrification change due to stepwise load operation (in the range of 250.0 ppm)

1) Determination of the parameters of MLSS concentration

Based on the basic formula for maintaining the MLSS concentration in the aeration tank, the inflow amount Q (m ³ / d) of the wastewater, the SS concentration S (mg / L) of the return sludge, and the SS concentration mg / L) and the sludge return amount Q _r (m ³ / d), the optimum MLSS concentration is determined through proper management and maintained, and the nitrogen removal amount can be maximized.

On the other hand, MLSS concentration can be maintained by determining the MLSS concentration to be controlled and controlled and determining the excess sludge withdrawal from the following equation.

Therefore, the controllable parameters are selected as the incoming sludge amount (Q, S) and the returned sludge amount ( _Qr , R). However, as a result of the analysis of Q and S during the analysis period, the experiment is regarded as a fixed factor within the error range of Q (± 3.0 m ³ / d) and S (± 200 ppm) of the fluctuation value.

2) Determination of MLSS concentration

The controllable parameters are set as the return sludge amount ( _Qr ) and the SS concentration (R) of the return sludge, and the respective levels are determined as follows. The sludge return amount setting considering the pump capability and the sludge withdrawal amount to the outside are adjusted Adjust the SS concentration of the sludge. That is, Q is 30 m ³ / d and R is 20,000 ppm. The conveying sludge amount (Q _r ) is in the range of 1 to 10, 2 to 20 and ^{3 to 30} m ³ / d, and the SS concentration (R) of the conveyed sludge is in the range of 1 to 18,000, 2 to 20,000 and ³ to 30,000 ppm , The total Batch method was applied in the range of 2 factors 3 as shown in [Table 3-1].

[Table 3-1]

3) Application process design

The MLSS concentration of each process was set as a criterion, and the removal efficiency of T-N according to the concentration increase / decrease concentration of each group was analyzed. In order to find the optimum condition, the process as shown in FIG. 2 was designed.

T-N removal efficiency according to MLSS concentration change

Table 2 shows the changes of T-N concentration in the process for T-N treatment in the current semiconductor wastewater to determine the parameters affecting the T-N removal rate according to MLSS concentration change.

As shown in [Table 2], the treatment efficiency of TN decreased from the point of merging with the wastewater of SC-1 (Standard Clean 1) wastewater. The parameters affecting the TN removal rate And to set priorities and conduct experiments.

[Table 2] shows the results of the experiment to examine the T-N treatment efficiency according to MLSS concentration change.

[Table 2]

In addition, TN removal efficiency according to the parameter control of the amount of return sludge Q _r and the return sludge SS concentration is R [Table 3] and equals, Q _r is 20m ³ / d, R is removed, the most favorable concentration in TN 2,2000ppm Efficiency. However, this is an effect that occurs when each factor is independent, not because it does not take into account the level of each factor.

[Table 3]

In the interaction effect, Q _r 20 m ³ / d, R 20,000 ppm and Q _r 10 m ³ / d, R 22,000 ppm are almost equal, and the average values of these are Q _r 15 m ³ / d and R 21,000 ppm It is necessary to confirm whether the efficiency is similar or not.

Therefore, although Q _r can be easily controlled by controlling the pump operation time, it is difficult to maintain 22,000 ppm due to the draw-out cycle of sludge, capitalization and corruption. Therefore, The results are shown in Table 4 as a result of reviewing whether MLSS concentration and TN removal rate were satisfied at the level of 21,000 ppm.

As a result, the TN removal rate was 82.7 ~ 86.4%, and the MLSS concentration in the aeration tank remained in the range of 3,490 ~ 3,580ppm. That is, the MLSS concentration in the aeration tank was kept constant at 3,500 ± 50 when the operation conditions of Q _r 15 ^{~ 20} m ³ / d and R 20,000 ~ 21,000 ppm were maintained, and 84.4% removal exceeding the TN removal target of 75.0% The effect was shown, and it was determined as the operating condition.

[Table 4]

Change of T-N removal rate due to stepwise load operation

As a result of evaluating the adequacy of the nitrification reaction by the stepwise load operation of the semiconductor cleaning wastewater, as shown in FIGS. 5 to 9, when the TN concentration of the influent water was 50%, 100 ppm, 150 ppm, 200 ppm and 250 ppm, respectively, The average concentrations of the treated water were 9.0 ppm, 16.0 ppm, 38.0 ppm, 111.0 ppm, and 143 ppm, and the TN removal ratios were 83.0%, 85.0%, 76.0%, 46.0%, and 43.0%, respectively. Especially, at T-N concentration of 100.0 ppm, the removal rate was the best at 85.0%, and the denitrification reaction was mostly denitrification when ammonia nitrogen was oxidized to nitrate nitrogen.

Since the average concentration of BOD in the semiconductor wastewater is 1,500 ppm and the average concentration of nitrogen is 300 ppm, the C / N ratio is 3 or more, so that external organic carbon injection is unnecessary. .

Above 200 ppm, the nitrification-induced microbial impact was expected and the T-N removal rate was decreased. It is important to sufficiently dilute the concentration of the raw water in consideration of the treatment capacity when introducing it into the demonstration plant, and to introduce the nitrate microorganism below the limit concentration. In order to prevent the impact load of the nitrifying microorganism and increase the activation, Expansion or improvement is necessary.

Optimal process design for removal of high concentration T-N

Based on the experimental results, the optimum process was designed as shown in Fig. 10 to remove the high concentration TN. The operation conditions were set to 30 m ³ / d, 700 ppm, and S 20,500 ± 500 ppm of precipitated sludge at 15 to 20 m ³ / d And the MLSS concentration in the aeration tank is designed to control Q _r and R so as to maintain 3,500 ± 50 ppm.

The TN removal rate is as shown in [Table 5]. The average TN concentration of influent is 101.0 ppm, the average TN concentration of treated water is 15.0 ppm, and the TN removal rate is 85.0% The water quality of treated water was confirmed to be good.

Claims

Maintaining an MLSS concentration of 3,500 ± 50 ppm by installing an anoxic tank and constructing a return line between an aeration tank and a settling tank for high efficiency treatment of semiconductor wastewater containing high concentration nitrogen;

The method of claim 1, further comprising:
The sedimentation sludge 15 to ²⁰ m ³ / d of the inflow amount (Q) 30 cm ³ / d of the semiconductor cleaning wastewater, the SS concentration (S) 700 ppm of the inflow water and the SS concentration (R) 20,500 ± 500 ppm of the return sludge is returned to the anoxic tank MLSS concentration in the step of transferring the appropriate Q _r and R to maintain 3,500 ± 50ppm.