• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.659-663
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• 2021

10 m³/min (CMM) multi-pollutants abatement system was successfully developed by effectively integrating ozone oxidation, wet scrubbing, and wet electrostatic precipitation for the simultaneous removal of particulate matters (PMs) and NOx in a semiconductor fabrication process. The sophisticated control and optimization of operating parameters were conducted to maximize the destruction and removal efficiency of NOx. In particular, the stability test of a wet electrostatic precipitator was carried out in parallel for 30 days to validate the reliability of core parts including a power supply. An O₃/NO ratio, which is the most important operating parameter, was optimized to be about 1.5 and the optimization of wet scrubbing with a reducing agent made it possible to analyze the contribution of neutralization reaction.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.178-182
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• 2010

Simultaneous removal reaction for NOx, soot over Pt catalysts using various $TiO_2$ as support was studied. The catalytic tests ware carried out injectin NO, soot, NO and soot simultaneously on each catalysts. As results, it showed different NOx removal efficiency and soot oxidation rate according to various kinds of $TiO_2$. Onset temperature of soot oxidation has a correlation to $NO_2$ generated for the independently performed NOx. It was investigated that NO to $NO_2$ oxidation was intimately related to crystallite size and surface area, and it has a tremendous impact on Pt aggregation on the catalyst surface and catalyst' reducibility. Therefore, we concluded that major index of the reaction was physico-chemical properties of catalyst' supports.

• Journal of Environmental Science International
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• v.23 no.5
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• pp.903-910
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• 2014

This study examined the treatment characteristics of hard-to-degrade pollutants such as TCE which are found in organic solvent and cleaning wastewater by nZVI that have excellent oxidation and reduction characteristics. In addition, this study tried to find out the degradation characteristics of TCE by Fenton-like process, in which $H_2O_2$ is dosed additionally. In this study, different ratios of nZVI and $H_2O_2$, such as 1.0 mM : 0.5 mM, 1.0 mM : 1.0 mM, and 1.0 mM : 2.0 mM were used. When 1.0 mM of nZVI was dosed with 1.0 mM of $H_2O_2$, the removal efficiency of TOC was the highest and the first order rate constant was also the highest. When 1mM of nZVI was dosed with 0.5 mM of $H_2O_2$, the first order rate constant and removal efficiency were the lowest. The size of first order rate constant and removal efficiency was in the order of nZVI 1.0 mM : $H_2O_2$ 1.0 mM > nZVI 1.0 mM : $H_2O_2$ 2.0 mM > nZVI 1.0 mM : $H_2O_2$ 0.5 mM > $H_2O_2$ 1.0 mM > nZVI 1.0 mM. It is estimated that when 1.0 mM of nZVI is dosed with 1.0 mM of $H_2O_2$, $Fe^{2+}$ ion generated by nZVI and $H_2O_2$ react in the stoichiometric molar ratio of 1:1, thus the first order rate constant and removal efficiency are the highest. And when 1.0 mM of nZVI is dosed with 2.0 mM of $H_2O_2$, excessive $H_2O_2$ work as a scavenger of OH radicals and excessive $H_2O_2$ reduce $Fe^{3+}$ into $Fe^{2+}$. As for the removal efficiency of TOC in TCE by simultaneous dose and sequential dose of nZVI and $H_2O_2$, sequential dose showed higher first order reaction rate and removal efficiency than simultaneous dose. It is estimated that when nZVI is dosed 30 minutes in advance, pre-treatment occurs and nanoscale $Fe^0$ is oxidized to $Fe^{2+}$ and TCE is pre-reduced and becomes easier to degrade. When $H_2O_2$ is dosed at this time, OH radicals are generated and degrade TCE actively.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.4
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• pp.439-446
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• 2009

This study was performed to evaluate SND(simultaneous nitrification and denitrification)efficiency, nitrogen removal efficiency and filtration function of non-woven fabric by using submerging MBR packed with granular sulfur covered with non-woven fabric filter. Synthetic wastewater was used as influent wastewater. Concentration of $NH_4{^+}-N$ in influent was maintained about 40 mg/L and the experiment was performed in four phases according to the flow rate. Nitrogen loading rate divided four phases ranging from $0.04 kg\;NH_4{^+}-N/m^3-day$ to $0.16 kg\;NH_4{^+}-N/m^3-day$. As a result, the maximum $NH_4{^+}-N$ removal rate was accomplished at $0.142 kg\;NH_4{^+}-N/m^3-day$ in nitrogen loading of $0.147 kg\;NH_4{^+}-N/m^3-day$. Nitrification efficiency was higher than 95% in all phases. $NO_3{^-}-N$ loading rate was adjusted ranging from $0.22 kg\;NO_3{^-}-N/m^3-day$ to $0.89 kg\;NO_3{^-}-N/m^3-day$. The maximum $NO_3{^-}-N$ removal rate was accomplished up to $0.71 kg\;NO_3{^-}-N/m^3-day$ in $NO_3{^-}-N$ loading of $0.89 kg\;NO_3{^-}-N/m^3-day$. The maximum $NO_3{^-}-N$ removal efficiency was 95% in $NO_3{^-}-N$ loading of $0.22 kg\;NO_3{^-}-N/m^3-day$. T-N removal rate was 90% and concentration of T-N in effluent was 3.7 mg/L in T-N loading rate of $0.039 kg\;NO_3{^-}-N/m^3-day$. In this study, TMP in reactor with and without non-woven fabric filter were observed to define fouling of hollow-fiber membrane module. Reaching time to standard washing pressure(22 cm Hg) of two reactors were 29 days with non-woven fabric But the reactor without non-woven fabric reached standard washing pressure only after 4 days. Accordingly, non-woven fabric was demonstrated the superiority as a filtration ability. With high nitrogen removal rate and decreasing of fouling of membrane, MBR packed with granular sulfur covered with non-woven fabric filter submerging in activated sludge aeration tank can be used as an advanced treatment process.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.3
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• pp.248-256
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• 2016

The main purpose of this paper was to analyze the removal characteristics of gas/particulate phase pollutants for the present system. Experimentally, we performed to estimate the pressure drop and air pollution removal efficiency with physical variables such as stage number, tube velocity, tube diameter, water spray ($NH_4OH$), and so on. It was concluded that the pressure drop was shown below $111mmH_2O$ lower than that of the existing scrubber (centrifugal spray chamber, over 200 mmAq) at inlet velocity 3.46 m/s and 5 stage. The particular removal efficiency of this system was to be significantly higher at 99.8% in comparison with that of the existing scrubber for 5 stage, inlet velocity 3.46 m/s and $NH_4OH$ (aq) 300 mL/min. It was estimated that the removal efficiencies of $SO_2$ and $NO_2$ were 80% and 70% at system inlet velocity 2.07 m/s and $NH_4OH$ (aq) 300 mL/min respectively. Additionally, the present collection system was to be considered as an effective compact system for simultaneous removal of air pollutants (gas/particulate) due to much higher removal efficiency and appropriate pressure drop without a demister.

• Journal of Microbiology and Biotechnology
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• v.10 no.3
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• pp.419-422
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• 2000

A three-phase fluidized-bed bioreactor including Thiobacillus sp. IW was tested to remove H_2S and $NH_3$ simultaneously. The inlet $H_2S$ was oxidized to $SO_4^{2-}$ by Thiobacillus sp. IW, and the $NH_3$ reacted with the $SO_4^{2-}$ to form $(NH_4)_2SO_4$. The removal efficiency of $H_2S$ was 98.4-99.9% for an inlet concentration of 36-730 ppm and that of $NH_3$ was 60.2-99.2% for an inlet concentration of 45-412 ppm. The removal efficiency of $NH_3$ was reduced when the inlet loading rate of $NH_3$ was increased above 10 mg/l/h. When the bioreactor was operated for 25 days with a lower inlet concentration of $NH_3$ compared with the of $H_2S$, the bioreactor exhibited an excellent performance with a stable pH, dissolved oxygen content, and cell concentration.

• Journal of Environmental Science International
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• v.14 no.9
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• pp.861-871
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• 2005

This study was carried out to get more operational characteristics of Anoxic(anaerobic)-Oxic-Anoxic-Oxic $(AO)_2$ sequencing batch biofilm reactors (SBBRs) at the low TOC concentration, The operating time in anoxic (anaerobic) time to oxic time was I : I. Experiments were conducted to find the effects of the aeration time distribution on the organic matters and nutrients removal. Three lab-scale reactors were fed with synthetic wastewater based on glucose as carbon source. During studies, the operation mode was fixed. The first aeration time to the second aeration time in SBBR-I was 2 : 3, and those in SBBR-2 and SBBR-3 were I : 4 and 3 : 2, respectively. The organic removal efficiency didn't show large difference among three reactors of different aeration time distribution. However, from these study results, the optimum aeration time distribution in the first and the second aeration time for biological nutrient removal was shown as 3 : 2. The release of phosphorus was inhibited at the second non-aeration period because of the low TOC concentration and the nitrate produced by the nitrification at the first aeration period.

• Journal of Soil and Groundwater Environment
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• v.16 no.4
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• pp.31-37
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• 2011

The feasibility study of soil flushing was investigated to remediate lubricant oil and zinc contaminated railway soil. In this study, mixed washing agents of surfactant and inorganic acid/base were used for the simultaneous removal. The mixed washing agent of non-ionic surfactant and HCl removed 15% of the lubricant oil and 40% of zinc, respectively. Alkaline-enhanced soil washing process increased the removal of lubricant oil up to 40%. This is because alkaline solution reduced the interfacial tension between water phase and lubricant oil phase due to the soap formation reaction. To simulate in-situ soil flushing for the remediation of railroad-related contamination, two dimensional soil flushing was carried out based on the results of batch soil washing. In the soil flushing, the removal efficiencies of lubricant oil and zinc were 34% and 16%, respectively. Even though the removal efficiency was low, the mixed washing agent can remove metal and lubricant oil simultaneously.

• Environmental Engineering Research
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• v.14 no.4
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• pp.238-242
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• 2009

This study investigated the effects of organic loading rates on simultaneous carbon and nitrogen removal in an innovative fixed-film aerobic bioreactor. The fixed-film bioreactor (FFB) was composed of a two-compartment aeration tank, in which a synthetic filamentous carrier was submerged as biofilm support media, and a settling tank which polyvinylidene media (Saran) was used as settling aid for suspended solids. Three different organic loading rates, ranging from 0.92-2.02 kg chemical oxygen demand/$m^3$/day were applied by varying hydraulic retention time (HRT). The total soluble organic carbon removal efficiencies were in the range of 90-97%. The removal efficiency of ammonia was found to be in the range of 70-84%. Total nitrogen removal efficiency was found to be in the range of 40-45%, which indicates that denitrification reactions occurred simultaneously in the attached biofilm on the fibrous media in the aeration tank. The settling performance of suspended solids was significantly improved due to the presence of Saran media in the settling compartment, even for a short HRT. The fixed-film aerobic bioreactor used in this study demonstrated efficient treatment efficiency even at higher organic loading rates and at short HRTs.

• The Korean Journal of Ceramics
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• v.5 no.3
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• pp.284-287
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• 1999

CuO catalyst-coated alumino-silicate fiber filters were prepared for the simultaneous removal of particulate matter and gaseous contaminants such as NOx and SOx. Hot gas cleaning experiments similar to Shell UOP process other than the catalyst supporting materials were carried out between 300 and $500^{\circ}C$ for the evaluation of the gas removal efficiency of the catalytic filter. Experimental results showed that removel efficiency for $SO_2$ was greater than 99% in the temperature range 450~$500^{\circ}C$ and more than 90% of NO was collected between 350 and $370^{\circ}C$. It was found that the higher the CuO content, the higher the removal efficiency for $SO_2$. Removal efficiency for NO was more affected by the gas cleaning temperature than by the CuO content in the catalyst-filter.