• Journal of Environmental Health Sciences
• /
• v.26 no.4
• /
• pp.49-57
• /
• 2000

This study was carried out to find the optimal condition to treat refractory organic matter which can’t treat clearly with biological treatment and to find the optimal division dosage and division dose timing in the modification of Fenton oxidation which is used resolve the problem that hydrogen peroxide is too expensive. The results are following; 1. The highest TOC removal efficiency was 41% and color removal efficiency was 64% when the dilution magnitude of leachate is fold. This suggests that dilution is efficiency when high concentration of leachate is treated. 2. The removal efficiency of TOC and color increased up to the molar ratio between ferrate and hydrogen peroxide was 1:1. However above that ratio, removal efficiency hardly increased. The highest removal efficiency of TOC and color were 38% and 71% when the mole ratio of ferrate to hydrogen peroxide was 1.5:1. 3. When the mole ratio between ferrate and hydrogen peroxide was fixed, the removal efficiency of TOC and color increased as the dosage of hydrogen peroxide increased. 4. pH of samples were adjusted at pH 3, 5, 7, 9, 11. After oxidation reaction, pH of samples were dropped to 2.59, 2.54, 5.34, 6.36 and 9.68. The highest color removal efficiency was 75.7% when initial pH was at pH 7. 5. The removal of TOC and color was ended within 10. min. and the removal efficiency increased logarithmically within 10min. However after 10 min., the removal efficiency of hardly increased. 6. The color removal efficiency was higher with modification of fentone oxidation than that with fentone oxidation by 5%. Optimal division dosage ratio was 1:1 and optimal dose timing ratio was 2:1. However the TOC removal efficiency was not higher with modification of Fenton oxidation than that with Fenton oxidation.7. The CO $D_{Mn}$ /BO $D_{5}$ Ratio decreased with the time went by. It meant bioresolution increased as time went by. However, after 15 min., the CO $D_{Mn}$ /BO $D_{5}$ Ratio did not decrease any more. 8. In the case of $H_2O$$_2$ Divisiom Dose experiment, the increase of bioresolution was highest at the $H_2O$$_2$ Division dosage Ratio of 3:7.3:7.

• Journal of Environmental Science International
• /
• v.17 no.3
• /
• pp.335-342
• /
• 2008

This study based on electro-coagulation & oxidation reaction is applied to wastewater treatment. Electro-oxidation reaction is used to remove cyanide(CN) which is contained in plating wastewater. Cyanide is transferred by gases such as $NH_3,\;NO_x,\;CO_2$. Analysis result and removal efficiency of Cyanide which is contained in heavy metal wastewater of plating plant, are shown as following paragraph. In electrode arrangement experiment, removal efficiency of carbon electrode(-)/STS316L electrode(+) arrangement method is superior to carbon electrode(-)/carbon electrode(+) arrangement method. Removal efficiencies of cyanide in different HRT such as 30 min, 45 min, 60 min, 75 min and 90 min are 85.5%, 93.1%, 98.0%, 98.7% and 99.4% respectively in carbon electrode(-)/STS316L electrode(+) arrangement method. Finally we can estimate the critical point at HRT of 60 min which the variation of removal efficiency is decreased and HRT to obtain removal efficiency of less than 1 mg/LCN is minimum 90 min.

• Nuclear Engineering and Technology
• /
• v.36 no.4
• /
• pp.304-315
• /
• 2004

The ageing effects of radionuclides in radioactive soil on remediation using the electrokinetic method were analyzed. Comparative experiments were conducted for the reactive soil around a TRIGA research? reactor contaminated with $^{137}Cs\;and\;^{60}Co$ for 15 years and the non-reactive soil that was intentionally contaminated with $Cs^+\;and\;Co^{2+}$ for 3 days. It was observed that because of an aging effect on $^{137}Cs$, the efficiency of removing it decreased. $H_{2}SO_4$ used as an additive to increase the removal efficiency showed a higher removal capability than other chemicals for both $^{137}Cs\;and\;^{60}Co$. The efficiency of removing radionuclides from the radioactive soil in the column was proportional to the capability of the added chemical to extract radionuclides. It took 10 days to achieve a $54\%$ removal of $^{137}Cs$ and a $97\%$ removal of $^{60}Co$ from the soil. The volume of the soil wastewater discharged from the soil column by the electrokinetic method was $20\%$ below that for soil washing.

• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2116-2121
• /
• 2008

Removal of particles at rich $CO_2$ condition has been important in the gas cleaning for $CO_2$ capture in Oxy-fuel combustion. Electrostatic precipitators (ESPs) have been widely used to remove particles in exhaust gases from present air combustion. However, few studies on characteristics of ESPs under a $CO_2$ rich gas condition have been conducted. In this study, we investigated integration of electrostatic precipitators (ESP) for removing submicron particles along with corona discharge characteristics and collection efficiency of submicron particles at $CO_2$ rich condition. The overall performance of ESP is represented by collection efficiency as function of energy consumption. The experiment results showed that higher the concentration of $CO_2$ gas, the corona discharge currents were lower at the same applied voltages and the spark over occurred at lower voltages, and the collection efficiency of submicron particles under 50, 80% $CO_2$ conditions was much lower than that under 100% Air.

• Journal of Environmental Health Sciences
• /
• v.26 no.4
• /
• pp.9-14
• /
• 2000

In this study, the removal efficiencies of organics, nitrogens and phosphorus from municipal wastewater using $A^2$/O process were investigated. BO $D_{5}$ removal efficiencies were indicated 95% and 94% with HRT of 12 hr and 10 hr, respectively. CO $D_{Cr}$ average removal efficiency and concentration of effluent were indicated 87% and 34mg/$\ell$. SS average removal efficiency and concentration of effluent were indicated 93% and 4~17mg/$\ell$. T-N removal efficiency and concentration of effluent were shown as 60~80% and below 15mg/$\ell$. In aerobic basin, removal efficiency of N $H_4$-N was shown over 97% with N $H_4$-N volume load 0.16kg N $H_4$-N/㎥.d and in anoxic basin, denitrification efficiency was indicated over 80% with return sludge rate 0.5Q and internal recirculation rate 2.5Q. Removal efficiency and effluent concentration of phosphorus were shown over 80% and below 2 mg/$\ell$ with return sludge rate 0.5Q.Q.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.62 no.5
• /
• pp.39-46
• /
• 2020

This study evaluated the nitrogen oxide (NO_x) removal efficiency by air purification concrete blocks with titanium dioxide (TiO₂). The concrete in the mixtures had a 30% water:cement ratio, to which TiO₂ was added at 0%, 5%, and 10% of cement weight. The compressive strength reduction rate and removal efficiency of NO_x were investigated. The result of the compressive strength test in the study indicated that addition rate of TiO₂ did not lead to signifcant effect. In terms of the average removal efficiency of NO_x, mix No. 1 using a TiO₂ mixing ratio of 0% had a removal efficiency of 0.57% on average; thus, the removal effect w as not significant. For the other samples prepared by mixing, the average removal efficiencies for mix No. 2 (5% TiO₂) were 58.86% and 62.05% for normal and washing surface treatments, respectively, and those of sample No. 3 (10% TiO₂) were 59.94% and 67.61%. mixs No. 4 (5%) and No. 5 (10%), in which TiO₂ diluted with distilled water was sprayed onto the block surface, had an average NO_x removal efficiency of 61.72% and 68.48%, respectively. In terms of NOx removal efficiency, Mixs No. 3 and No. 5 with 10% TiO₂ were better than Mixs No. 2 and No. 4 with 5% TiO₂. In addition, analyzing the NO_x removal efficiency results from the fixing method, it was capable to apply mixing (washing) and the diluted spray methods. Therefore, it was found that the diluted spray method applied in this study can be employed in any manufacture of air purification concrete blocks.

• Journal of Korean Society for Atmospheric Environment
• /
• v.23 no.5
• /
• pp.539-546
• /
• 2007

Increasing emission of $CO_2$ significantly effects the global warming. Chemical absorption is one of separation methods of $CO_2$ from the industrial flue gases. In this study, the $CO_2$ removal efficiency as well as the $CO_2$ absorption amount of aqueous AMP (2-amino-2-methyl-1-propanol) solutions were measured using the continuous absorption and regeneration apparatus. We investigated the effect of aqueous AMP+AEPD(2-amino-2-ethyl-1, 3-propanediol) and AMP+TIPA (triisopropanolamine) solutions to enhance absorption characteristics of AMP. As a result of this study, the absorption amount and $CO_2$ removal efficiency were increased with adding TIPA into 30 wt.% AMP. The absorption amount and $CO_2$ removal efficiency of aqueous 30 wt.% AMP+5 wt.% TIPA solution were $1.70\;kg-CO_2/kg-absorbent$ and 91.1%, while those of aqueous 30 wt.% AMP solution were $1.58\;kg-CO_2/kg-absorbent$ and 89.3%. In addition, aqueous 30 wt.% AMP+5 wt.% TIPA solution used in the study revealed the high stripping efficiency, which was almost 98%, at the temperature of $110^{\circ}C$. Thus, the temperature of regenerator should be operated at $110^{\circ}C$.

• Journal of Korean Society of Water and Wastewater
• /
• v.25 no.3
• /
• pp.307-312
• /
• 2011

The potential of algal-bacterial culture was investigated for advanced treatment of animal wastewater. Fed-batch experiments were carried out to examine treatability of nitrogen and phosphorus in different microbial consortium: Chlorella vulgaris, activated sludge, three microalgae strains (Scenedesmus, Microcystis, Chlorella) and Bacillus consortium, and three microalgae strains and sludge consortium. Single culture of C. vugaris showed the better efficiency for nitrogen removal but was not good at organic matter and phosphorus removal compared with activated sludge. Three microalgae and Bacillus consortium was best culture among the culture and consortium for pollutants removal tested in this experiment. Effect of $CO_2$ addition was studied by using three microalgae and Bacillus consortium. $CO_2$ addition enhanced T-P removal efficiency up to 60%. However, removal efficiencies of T-N and ammonia nitrogen reduced on the contrary.

• Journal of the Semiconductor & Display Technology
• /
• v.11 no.3
• /
• pp.7-11
• /
• 2012

Among various wet cleaning methods, megasonic and jet spray gained their popularity in single wafer cleaning process for the efficient removal of particulate contaminants from the wafer surface. In the present study, we evaluated these two cleaning methods for particle removal efficiency (PRE) and pattern damage on the aluminum layered wafer surface. Also the effect of $CO_2$ dissolved water in jet spray cleaning is assessed by measuring PRE. It is observed that the jet spray cleaning process is more effective in terms of PRE and pattern damage compared to megasonic cleaning and the mixing of $CO_2$ in the water during jet sprays further increases the PRE. We believe that the outcome of the present study is useful for the semiconductor cleaning process engineers and researchers.

• Applied Chemistry for Engineering
• /
• v.28 no.5
• /
• pp.565-570
• /
• 2017

Tobacco smoke emitted during smoking is divided into a main-stream and side-stream smoke. Most of the tobacco smoke that spreads to a room while smoking is a side-stream one. The side-stream tobacco smoke is two to three times more harmful than that of the main-stream tobacco smoke. In this study, the removal efficiency of CO, $H_2S$, $NH_3$ and HCHO in a side-stream tobacco smoke using the doping component of $TiO_2$ photocatalysts was confirmed. As a result, CO was removed up to 78.37%, which indicated that the $TiO_2$ photocatalytic process is effective for CO removal. Also, the removal efficiencies of CO, $H_2S$ and HCHO were greatly affected by the amount of doped O and Si components of the $TiO_2$ photocatalyst. In conclusion, the more doped O and Si components had, the higher removal efficiencies of harmful substances were achieved.