• Journal of Korean Society of Environmental Engineers
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• v.38 no.9
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• pp.513-520
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• 2016

It is well known that volatile compounds including disinfection by-products as well as emissive dissolved gas in water can be removed effectively by air stripping. The micro-bubbles of flotation unit are so tiny as microns while the diameter of fine bubbles applied to air stripping is ranged from hundreds to thousands of micrometer. Therefore, the micro-bubbles in flotation can supply very wide specific surface area to transfer volatile matters through gas-liquid boundary. In addition, long emission time also can be gained to emit the volatile compound owing to the slow rise velocity of micro-bubbles in the flotation tank. There was a significant difference of the THMs species removal efficiency between air stripping and flotation experiments in this study. Moreover, the results of comparative experiments on the removal characteristics of THMs between air stripping and flotation revealed that the mass transfer coefficient, $K_La$ showed obvious differences. To overcome the limit of low removal efficiency of dissolved volatile compounds such as THMs in flotation process, the operation range of bubble volume concentration is required to higher than the operation condition of conventional particle separation.

• 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.

• Environmental Engineering Research
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• v.25 no.2
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• pp.135-146
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• 2020

This study was aimed to investigate the possibility of using raw and anaerobically-digested piggery wastewater as culture media for a green microalga Chlorella vulgaris (C. vulgaris). Due to high concentration of ammonia and dark color, the microalga did not grow well in this wastewater. In order to solve this problem, air stripping and NaOCl-treatment were applied to reduce the concentration of NH₃-N and the color intensity from the wastewater. Algal growth was monitored in terms of specific growth rate, biomass productivity, and nutrient removal efficiency. As a result, C. vulgaris grew without any sign of inhibition in air-stripped and 10-folds diluted anaerobically-digested piggery wastewater with enhanced biomass productivity of 0.57 g/L·d and nutrient removal of 98.7-99.8% for NH₃-N and 41.0-62.5% for total phosphorus. However, NaOCl-treatment showed no significant effect on growth of C. vulgaris, although dark color was removed greatly. Interestingly, despite that the soluble organic concentration after air stripping was still high, the biomass productivity was 4.4 times higher than BG-11. Moreover, air stripping was identically effective for raw piggery wastewater as for anaerobic digestate. Therefore, it was concluded that air stripping was a very effective method for culturing microalgae and removing nutrients from raw and anaerobically-digested piggery wastewaters.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.9
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• pp.935-939
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• 2006

The biological nutrient removal from domestic wastewater with low C/N ratio is difficult. Therefore, this study was performed to examine effect of operational parameters such as air supply, hydraulic retention time, pH on the nitrogen removal by ammonia stripping and to increase influent C/N ratio without required carbon source. The ammonia stripping system used for the bench-scale experiment in laboratory had a dimension of 15 cm diameter and 150 cm height. The ammonia stripping reactors were classified into two types, type AS I and type AS II, according to there using or not media. Results of the research showed that the T-N removal efficiency of AS I using plastic media is slightly higher than AS II without media. In experimental condition of air supply 30 L/min and pH 12.5, T-N removal efficiencies increased as HRT of ammonia stripping reactor became longer from 8 hr to 36 hr. In experimental condition of HRT 36 hr, it was also found that the T-N removal efficiencies improved through increase of air supply. On the other hand, C/N ratio of wastewater was increased from average 3.9 to 5.4 by ammonia stripping.

• Journal of Chest Surgery
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• v.43 no.4
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• pp.387-393
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• 2010

Background: The aims of the present study were to assess and compare mid-term clinical outcomes including recurrences between endovenous laser therapy (EVLT) and stripping. Material and Method: Between January 2007 and February 2010, 318 limbs in 237 patients with saphenous truncal varicosities were treated by laser energy using a 980 nm diode or were treated with conventional stripping. At the initial visit and at 1, 2, 6, 12, 18, 24, and 36 months postoperatively, clinical examination and questioning for Venous Clinical Severity Score (VCSS) as well as duplex ultrasonography were done. In order to compare clinical outcomes between the two treatment groups, EVLT versus stripping, all data were processed and analyzed. Result: There were no significant differences between the two treatment groups in the extent of the reflux and the number of insufficient perforating veins. The in EVLT and the stripping group at 12 months were $90.3{\pm}4.5%$ and $93.9{\pm}4.2%$, respectively (p>0.05). Total recurrence rates were 4.4% in the EVLT group and 1.5% in the stripping group (p>0.05). In both groups, the VCSS scores were significantly reduced at week 1, 1 month, and 2 months after EVLT or stripping (p<0.001). Conclusion: Efficiency in eliminating truncal saphenous vein incompetence and reducing venous clinical severity were equal in the two treatment groups.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.77-80
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• 2001

Groundwater, contaminated predominantly with aromatic compounds and chlorinated ethylene, could be biologically treated in a fluidized-bed reactor with immobilized cells. The decomposition efficiency for the aromatics was over 90% at the retention time of 2.5 h. The chlorinated ethylenes, especially trichloroethylene (TCE) and cis-dichloroethylene (DCE), could be decomposed only insufficiently. No anaerobic methane formation was observed for this groundwater even at a very low dissolved oxygen (DO) concentration of 0.75 mg/L. The variation of DO concentration resulted in an optimal value of 1.5 mg/L. The recycle of air waste could increase the utilization of oxygen. The amount of low boiling pollutants stripped out remained constant with the recycle, while for the higher boiling pollutants the stripping slightly increased. Using air instead of oxygen increases the flow rate of air waste, which is connected to a higher stripping of pollutants. In this investigation, the pollutant concentration in the air waste remained constant. The stripping of main pollutants did not exceed 0.3 %.

• 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.

• 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.

• Korean Membrane Journal
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• v.7 no.1
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• pp.28-33
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• 2005

The feasibility of producing sulfuric acid and ammonia water from ammonium sulfate was investigated by an integrated process including ammonia stripping (AS) and electrodialysis with bipolar membrane (EDBM). It was suggested that the production of sulfuric acid using ammonia stripping-electrodialysis with bipolar membrane (ASEDBM) was effective in obtaining high concentration of sulfuric acid compared with EDBM alone. AS was carried out over pH 11 and within the range of temperatures, $20^{\circ}C{\~}60^{\circ}C$. Sodium sulfate obtained using AS was used as the feed solution of EDBM. The recovery of ammonia increased from $40\%$ to $80\%$ at $60^{\circ}C$ due to the increased mobility of ammonium ion. A pilot-scale EDBM system, which is composed of two compartments and 10 cell pairs with an effective membrane area of $200 cm^2$ per cell, was used for the recovery of sulfuric acid. The performance was examined in the range of 0.1 M${\~}$1.0 M concentration of concentrate compartment and of $25 mA/cm^2{\~}62.5 mA/cm^2$ of current density. The maximum current efficiency of $64.9\%$ was obtained at 0.1 M sulfuric acid because the diffusion rate at the anion exchange membrane decreased as the sulfuric acid of the concentrate compartment decreased. It was possible to obtain the 2.5 M of sulfuric acid in the $62.5 mA/cm^2$ with a power consumption of 13.0 kWh/ton, while the concentration of sulfuric acid was proportional to the current density below the limiting current density (LCD). Thus, the integrating process of AS-EDBM enables to recover sulfuric acid from the wastewaters containing ammonium sulfate.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.6
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• pp.849-855
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• 2006

Taste and odor (T&O) problems in drinking water supplies caused by eutrophication have become increasingly important because aesthetic qualities are the primary measures by which consumers estimate the quality of their drinking water. In order to overcome T&O problem, it is necessary to early detection method for T&O compounds before these compounds enter to water treatment plant. In this background, a early waming device for T&O compounds was developed and its performance tested under different operating condition. According to the experimental results on the adsorption efficiency of T&O compounds, when the raw water flowrate was 5 mL/min, the optimum stripping time and air flowrate were 5 hrs and 0.5 L/min, respectively. Comparison of activated carbon showed that foreign activated carbon was better than domestic activated carbon in terms of adsorption efficiency.