• Proceedings of the Korea Air Pollution Research Association Conference
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• 2005.11a
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• pp.175-176
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• 2005

• Journal of Wetlands Research
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• v.18 no.3
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• pp.286-291
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• 2016

This study was carried out to evaluate the feasibility of air-stripping by DIWS(Dip Injection Wet Scrubber) system on high concentration of ammonia wastewater more than 10,000 mg/L. In the case of changing temperature from $30^{\circ}C$ to $70^{\circ}C$ maintaining pH 12.5 within the 72 hours, the removal efficiency of T-N by the present treatment plant was increased to 90.5% which was initially kept 70.3%. Although the high concentration of T-N with 9,120~12,955 mg/L was treated by micro-bubble through DIWS system maintaining the temperature of $30^{\circ}C$ within the 20 hours, the removal efficiency of T-N reached 91.9%, which indicated the possibility of air-stripping.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.8
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• pp.767-773
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• 2010

In recent years, there has been considerable concern over the release of methyl tert-butyl ether (MTBE), a gasoline additive, into the aquifers used as potable water sources. MTBE readily dissolves in water and has entered the environment via gasoline spills and leaking storage tanks. In this study air stripping and ozonation of MTBE in aqueous solution were performed in a laboratory scale batch reacter. The mass transfer rate (N) was evaluated and a values about $1.24{\times}10^{-6}\;mol{\cdot}sec^{-1}$ was found. In the ozonation of MTBE a 8.3% decrease of the COD and a 6.5% decrease of the TOC lead to BOD/COD = 0.03. The peudo first-order rate constants of the ozonation of MTBE was $3.75{\times}10^{-5}\;sec^{-1}$. The resulting Ea of 4.80 kcal；mol-1 was observed for molecular ozone reactions.

• Clean Technology
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• v.29 no.4
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• pp.297-304
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• 2023

The rapid advancement of the high-tech electronics industry has led to a significant increase in high-concentration ammonia wastewater. Various methods have been attempted to reliably treat wastewater containing high concentrations of ammonia, but no successful technology has yet been developed and applied. In this study, the removal efficiency and characteristics of ammonia nitrogen was evaluated according to changes in temperature, air loading rate, and liquid loading rate using a closed circulation countercurrent packed tower type demonstration facility for wastewater containing high concentrations of ammonia generated in the high-tech electronics industry. The temperature was varied while maintaining operating conditions of a wastewater flowrate of 20.8 m³ h^-1 and an air flow rate of 18,000 Nm³ h^-1. The results showed that at temperatures of 45,50,55, and 60℃, the removal efficiencies of ammonia nitrogen (NH₃-N) were 87.5%, 93.4%, 96.8%, and 98.7%, respectively. It was observed that temperature had the most significant impact on the removal efficiency of NH₃-N under these conditions. As the air loading rate increases, the removal rate also increases, but the increase in removal efficiency is not significant because droplets from the absorption tower flow into the stripping tower. Even if the liquid loading rate was changed by ±30%, the removal rate did not change significantly. This does not mean that the removal rate was unaffected, but was believed to be due to the relatively high air load rate. Through demonstration research, it was confirmed that ammonia stripping is a reliable technology that can stably treat high-concentration ammonia wastewater generated in the high-tech electronics industry.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.2
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• pp.73-79
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• 2006

Aeration is the most important and indispensable operation unit for the treatment of swine manure using aerobic liquid-composting process. The composting of swine manure depends on biological treatment process, but the highly concentrated ammonia nitrogen is required a pretreatment to expect the appropriate efficiency of the biological treatment process. In this study, pilot experiments have been carried out to estimate of the fit condition about ammonia stripping process as a pretreatment to aerobic liquid- composting. pH adjustment with $Ca(OH)_2$ was economically superior to use of NaOH and optimum pH of ammonia stripping was 12.3, ammonia nitorgen was rapidly removed as pH were increased at $$35^{\circ}C$$. When air stripping is performed before aerobic liquid-stripping, a high initial pH is required for complete ammonia removal and is additional effects such as organic substances, phosphorus, turbidity, and color removal. Stripping process was very efficient in the pretreatment of highly concentrated ammonia nitrogen for composting of swine manure. Emission rate of gaseous ammonia was $0.5355mole\;s^{-1}$ at initial time and $0.0253mole\;s^{-1}$ at finitial time. The fit condition of ammonia stripping in this study were at the temperature of $$35^{\circ}C$$, and the pH of 12.3 during 48 hours.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.135-147
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• 2007

Segregation in asphalt pavements occurs as a result of the non-uniform distribution of coarse and fine aggregates and causes premature distresses, such as cracking, raveling, and stripping. The effect of segregation on rutting, however, has not been clearly identified. Experimental and analytical work performed in this study indicates that rutting performance is affected by segregation of mixtures. However, the aggregate structure of mixtures appears to be a more critical factor that determines the rutting performance, rather than the level of segregation. Based on the field mixtures evaluated, an increase of coarse aggregate volume in an asphalt mixture is an important factor that results in good rutting performance. This effect holds true for mixtures with lower levels of air voids, but for mixtures with higher levels of air voids, the air voids effect becomes dominant, resulting in a reduction in rutting performance. An air void content of 10% appears to be a threshold that determines the rutting performance of Superpave mixtures. Once the air void content exceeds 10%, the rutting performance of Superpave mixtures decreases significantly, despite the coarse aggregate volume.

• Journal of Environmental Health Sciences
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• v.28 no.1
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• pp.51-65
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• 2002

This study was carried out to apply some basic physical and chemical treatment options including Fenton's oxidation, and to evaluate the performances and the characteristics of organic and nitrogen removal using lab-scale biological treatment system such as complete-mixing activated sludge and sequencing batch reactor(SBR) processes for the treatment of leachate from a municipal waste landfill in Gyeongnam province. The results were as follows: Chemical coagulation experiments using aluminium sulfate, ferrous sulfate and ferric chloride resulted in leachate CO $D_{Cr}$ removal of 32%, 23% and 21 % with optimum reaction dose ranges of 10,000～15,000 mg/$\ell$, 1,000 mg/$\ell$ and 500～2,000 mg/$\ell$, respectively. Fenton's oxidation required the optimum conditions including pH 3.5, 6 hours of reaction time, and hydrogen peroxide and ferrous sulfate concentrations of 2,000 ～ 3,000 mg/$\ell$ each with 1:1 weight ratio to remove more than 50% of COD in the leachate containing CO $D_{Cr}$ between 2,000 ～ 3,000 mg/$\ell$. Air-stripping achieved to remove more than 97% of N $H_3$-N in the leachate in spite of requiring high cost of chemicals and extensive stripping time, and, however, zeolite treatment removing 94% of N $H_3$-N showed high selectivity to N $H^{+}$ ion and much faster removal rate than air-stripping. The result from lab-scale experiment using a complete-mixing activated sludge process showed that biological treatability tended to increase more or less as HRT increased or F/M ratio decreased, and, however, COD removal efficiency was very poor by showing only 36% at HRT of 29 days. While COD removal was achieved more during Fenton's oxidation as compared to alum treatment for the landfill leachate, the ratio of BOD/COD after Fenton's oxidation considerably increased, and the consecutive activated sludge process significantly reduced organic strength to remove 50% of CO $D_{Cr}$ and 95% of BO $D_{5}$ . The SBR process was generally more capable of removing organics and nitrogen in the leachate than complete-mixing activated sludge process to achieve 74% removal of influent CO $D_{Cr}$ , 98% of BO $D_{5}$ and especially 99% of N $H_3$-N. However, organic removal rates of the SBR processes pre-treated with air-stripping and with zeolite were not much different with those without pre-treatment, and the SBR process treated with powdered activated carbon showed a little higher rate of CO $D_{Cr}$ removal than the process without any treatment. In conclusion, the biological treatment process using SBR proved to be the most applicable for the treatment of organic contents and nitrogen simultaneously and effectively in the landfill leachate.e.

• KSBB Journal
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• v.9 no.2
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• pp.180-185
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• 1994

The productivity of alkaloid in the airlift fermentor operation was less than that of suspension coltures of Eschscholtzia californica cells in the shake flask. To overcome the productivity reduction, a gas recycle airlift fermentor was developed because the gas-stripping in normal airlift fermentor was believed to play a significant role for productivity reduction. The alkaloid content in the gas recycle system with Eschscholtzia californica suspension cells was 2.7 times higher than that of normal airlift fermentor. The productivity of alkaloids and $CO_2$ concentration were affected by the volume of gas reservoir in the gas recycle airlift fermentor.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.261-266
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• 2001

Three innovative technologies to remediate trichloroethylene (TCE) in situ were (or currently are being) evaluated at a TCE-contaminated groundwater site at Edwards Air Force Base (AFB), California. The three technologies all make use of groundwater recirculation to obviate the need to pump contaminated groundwater to the surface fer treatment. The first technology, which implements aerobic cometabolic bioremediation to destroy TCE in situ, successfully reduced dissolved TCE concentrations from above 1 mg/L to 20-30 $\mu\textrm{g}$/L. The second technology, in-well vapor stripping (IWVS), is capable of treating dissolved TCE at concentrations in the tens to hundreds of mg/L. Finally, the third technology, bioenhanced in-well vapor stripping (BEHIVS): is a combination of the first two technologies, and is designed to reduce very high levels of TCE (tens to hundreds of mg/L) to concentrations that meet regulatory requirements 5 $\mu\textrm{g}$/L). Results of field evaluations of tile first two technologies are presented, and the design of the BEHIVS system. as well as model predictions of BEHIVS performance and the current status of the technology field evaluation. is discussed.

• Membrane Journal
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• v.1 no.1
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• pp.78-95
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• 1991

Water factory 21(WF 2) in Orange County California, is a advanced wastewater treatment(AWT) plant designed to reclaim biologically treated munidpal wastewater for injection into a seawater barrier system. Processes included are lime treatment air stripping, filtration, activated carbon adsorption, reverse osmosis(RO), and chlorination. The effectiveness of each treatment process is presented including pretreatment, RO dimineralization. The data collected show that the processes, including RO, used at WF-21 are capable of producing a very high quality water on a reliable basis. Treatment reduced all contaminants, to levels below national primary drinldng water regulation maximum contaminant levels. It was found that lime clarified secondary effluent can be used as feedwater to a RO dimineralizer. Experiments with new low pressure membrane(250psi) show great potential for reducing RO cost.