• Economic and Environmental Geology
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• v.55 no.5
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• pp.511-519
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• 2022

In order to develop an air-stripping based remediation process to remove the TOC (Total Organic Carbon) in groundwater around the underground LPG storage cavern, the laboratory scale experiments at various conditions (change of air injection volume and temperature, the application of ultrasonic treatment, etc.) for two types of groundwater (initial TOC concentration of 608 mg/L and 153 mg/L, respectively). From results of experiment, as the air injection rate for stripping into groundwater increased from 2 L/min to 11 L/min and as the air-stripping time increased from 1 hour to 24 hour, the TOC removal efficiency of air-stripping increased. However, the TOC concentration of treated groundwater was higher than the discharge tolerance limit (100 mg/L) even after 24 hour stripping at the maximum air injection rate of 11 L/min. The main compounds of the TOC in groundwater were identified as methanol and propane and the long stripping time (more than 24 hour) was needed to separate the methanol from groundwater because of the affinity between water and methanol. At 20℃ and 4 L/min of air injection, the TOC removal efficiency increased to 59.1% after 24 hour air-stripping. When the temperature of groundwater increased to 30℃ and 40℃, the TOC removal efficiency increased up to 80.0% and 82.8%, suggesting that more than 24 hour air-stripping at 40℃ is needed to lower the TOC concentration to below 100 mg/L and the additional TOC removal process as well as the air-stripping is necessary. When the temperature increased to 60℃ and the ultrasonic treatment was conjugated with the air-stripping, the TOC removal efficiency increased to 87.8% within 5 hour stripping and the final TOC concentration (72.4 mg/L) was satisfied with the TOC discharge tolerance limit. The TOC removal efficiency for groundwater having low TOC concentration (153 mg/L) also showed similar removal efficiency of 89.7% (the final TOC concentration: 18.9 mg/L). Results in this study supported that the air-stripping conjugated with the ultrasonic treatment could remove successfully the TOC in groundwater around the underground LPG strorage cavern.

• Resources Recycling
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• v.12 no.3
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• pp.31-37
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• 2003

A study on the characteristics of ammonia desorption from aqueous solutions has been performed by air stripping as the first stage of ammonia recycling for the preparation of ammonium sulfate from it. For air stripping experiments, a stripping column made with acrylic tube of 40 mm diameter was employed and compressed air was injected into solutions through air sparger equipped at the bottom of stripping column. As a result of experiments, the stripping efficiency was increased with the aqueous pH and it was found that the appropriate pH for air stripping of ammonia was between pH 10 and 12. As far as the effect of air flow rate on ammonia stripping was concerned, ammonia stripping was not proportional to the air flow rate although it was affected by the air flow rate to some extent. Moreover, when more than 20 cm of water height was maintained, total ammonia desorbed from solution was not varied with the water height. Stripping temperature was also found to play an important role in ammonia desorption and about 90fo of initial ammonia was desorbed in 14 hours at pH 12.8 and at $60^{\circ}C$ Finally, it was believed that stripping temperature as well as the aqueous pH was one of the most important factors in air stripping of ammonia.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.5
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• pp.523-529
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• 2008

Algal blooms in a local eutrophic lake often produces the musty and earthy taste & odor problems. Since the odor causing compounds(OCCs) including geosmin and 2-MIB have their own volatility, the OCCs can be removed from water by air stripping methods. Removal of TON(threshold odor number) as an index for OCCs could be fitted well with the first order equations($R^2=0.9$ above), where the air stripping coefficient of TON, k was in the range between 0.0055 and 0.0097 according to the aeration time. k within 30min aeration tests was 0.0097, while it was 0.0055 where the aeration time extended to 150min. With 15 mg/L of PAC, removal of TON was not simulated with 1st order equation within 30min aeration. Within 30min aeration, OCCs rather than geosmin and/or 2-MIB could be removed easily by air stripping or PAC adsorption, while OCCs such as geosmin and/or 2-MIB could be removed slowly by air stripping after 30min aeration. Geosmin and 2-MIB were not readily removed by air stripping(k of them were 0.0018~0.0047 and 0.0018~0.0034, respectively at different air flow rates). Geosmin could be removed by air stripping a little better than 2-MIB.

• Journal of the Korean Society of Industry Convergence
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• v.5 no.3
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• pp.213-218
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• 2002

Total nitrogen is a major pollutant which mostly causes eutrophication and red tide. Wastewater effluent from printing of cotton-viscose rayon containing high concentrations of total nitrogen can not be effectively treated with a typical biological treatment process. This paper provides a new treatment process and experimental results for the removal of high strength nitrogen from dyeing wastewater. The optimum conditions of air stripping for the removal of total nitrogen include around pH 12, temperature $60^{\circ}C$ with 60 minutes of stripping time. In case of a filtration-air stripping process, an initial level ($500mg/{\ell}$) of total nitrogen was significantly reduced to below $60mg/{\ell}$. Deconite was synthesised for further decomposition of organic nitrogen. Thus, a filtration-decomposition-air stripping process was possibly achieved, by which a high level ($900mg/{\ell}$) of total nitrogen was effectively removed to below $60mg/{\ell}$ P. Finally, a continuous new process for the removal of total nitrogen is proposed and confirmed, based on batch experimental results, and its process validity is further discussed throughout.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.455-460
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• 2008

Powered activated carbon(PAC) has been widely applied for controling odor causing compounds(OCCs) from water treatment plants. Because of their volatility, the OCCs can also be removed from water by air stripping methods. In this study, OCCs removal was tested with PAC adsorption, air stripping, and both PAC adsorption and air stripping from the Taecheong lake water. Removal efficiency of OCCs in terms of threshold odor number(TON) were 39.6% by both PAC (15mg/L) adsorption and aeration for 30 min, 33.6% by PAC(15mg/L) adsorption alone for 30 min, and 22.9% by aeration alone for 30 min, respectively. OCCs could be removed up to 50% by aeration for 120 min without PAC adsorption. At an extended aeration with 15mg/L of PAC, OCCs removal occurred mainly by PAC adsorption within 30 min aeration while it continued by air stripping afterward. At simulated jar tests with the raw water, removal efficiencies of geosmin and MIB were 48.3, 36.1% by coagulation and sedimentation without PAC addition. With 15mg/L of PAC on the same jar tests, the removal efficiencies were 83.1, 60.1%, respectively. Without PAC, OCCs could be possibly removed by stripping during the agitation processes.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.1
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• pp.119-125
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• 1999

Conventional interproximal stripping using abrasive strips is normally limited to the anterior teeth. The strips must be forced between the contact points of the teeth creating patient discomfort and the risk of cutting gingival tissue. Air-rotor stripping(ARS) with Essix anterior anchor enables the clinician to remove a precise amount of interproximal enamel to create space, primarily in the buccal quadrants, for aligning or retracting teeth. In selected cases, ARS can resolve significant differences in ratios of tooth site to arch length, and the technique can become an alternative to extraction or expansion. ARS can create substantially more space than that is usually obtained by conventional interproximal stripping, and it can be done at any time during treatment without discomfort to the patient and without adversely affecting the function of the dentition, interocclusal relations, or tooth form.

• Korean Journal of Food Science and Technology
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• v.27 no.2
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• pp.176-180
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• 1995

Direct contact heat exchange (DCHE) method has been employed to investigate the separation of ethanol from dilute aqueous solutions. Bubbles at high temperature were dispersed into a continuous liquid phase, generating temperature gradient in air-liquid interface, which causes heat and mass transfer accordingly. The experiments were performed in the ranges of jet regime air flow. The air-water stripping coefficient increased $5{\sim}10,\;and\;1{\sim}1.5$ times as temperature and air flow rate increased, respectively. The recovery ratio based on the initial ethanol concentration reached into 80% at the air flow rate of 84.88 m/min. The initial ethanol concentration showed little effect on the stripping coefficient and the recovery ratio.

• 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 for Atmospheric Environment
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• v.9 no.E
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• pp.382-389
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• 1993

An evaluation of a plasma reactor was conducted to investigate its potential as a feasible and economical off-gas control technology for an air stripping tower (AST). The plasma reactor was powered by an alternating current with frequencies up to 1000Hz. The study showed that over 90% conversion of gas-phase trichloroethylene (TCE) can be achieved. An optimum frequency for the laternating current existed for maximum power input. The optimum frequency was dependent on the reactor geometry and the primary voltage applied. for a fixed geometry, a plasma reactor has a limited capacity for flow rate. Even though it is a feasible process to control off-gases, further investigations should be conducted to develop a more economic process.

• 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.