• Journal of the Korean Wood Science and Technology
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• v.22 no.3
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• pp.51-58
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• 1994

Environmental conservation has become one of the greatest concerns of all the people in the world. This issue is related to wood utilization in two major view points such as carbon dioxide emitted by the use of manufacturing energy and absorbed during the growth of trees. Wood construction materials require less manufacturing energy, which, in turn, means less carbon dioxide emission. In addition, wood keeps absorbed carbon in itself as far as it is not burnt. Therefore, wood is environmentally superior to other materials in terms of potential effects on atmospheric carbon dioxide. As examples of the environmental effect of wood utilization, the following two results were obtained: 1) If wood construction becomes popular in Korea as in Japan, more than 24% of carbon dioxide emission during construction of residential housings can be reduced: and 2) If aluminum windows are substituted by wood windows, more than 19% of carbon dioxide emission can be reduced. If the principle of "cut and plant" is kept well, wood is the best construction material for environmental protection as well as human residence.

• 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.