• Journal of Soil and Groundwater Environment
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• v.10 no.4
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• pp.45-53
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• 2005

The objective of this study is to evaluate the effects of changes in soil temperature on biodegradation rate of diesel compounds from a field pilot test using hot air injection process. Total remediation time was estimated from in-situ biodegradation rate and temperature for optimum biodegradation. All tests were conducted by measuring in-situ respiration rates every about 10 days on highly contaminated area where an accidental diesel release occurred. The applied remediation methods were hot air injection/extraction process to volatilize and extract diesel compounds followed by a bioremediation process to degrade residual diesels in soils. Oxygen consumption rate varied from 2.2 to 46.3%/day in the range of 26 to $60^{\circ}C$, and maximum $O_2$ consumption rate was observed at $32.0^{\circ}C$. Zero-order biodegradation rate estimated on the basis of oxygen consumption rates varied from 6.5 to 21.3 mg/kg-day, and the maximum biodegradation rate was observed at $32^{\circ}C$ as well. In other temperature range, the values were in the decreasing trend. The first-order kinetic constants (k) estimated from in-situ respiration rates measured periodically were 0.0027, 0.0013, and $0.0006d^{-1}$ at 32.8, 41.1, and $52.7^{\circ}C$, respectively. The estimated remediation time was from 2 to 9 years, provided that final TPH concentration in soils was set to 870 mg/kg.

• Journal of Chest Surgery
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• v.38 no.4 s.249
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• pp.271-276
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• 2005

We analysed differences in operative methods and postoperative outcome according to the severity of preoperative cyanosis in adult ToF (Tetralogy of Fallot) patients. Material and Method: From August 1989 to June 2001, thirty three adult patients, 18 females and 15 males, underwent total correction for ToF. Their age ranged from 15 years to 54 years (median: 34). Patients were divided into 2 groups by preoperative $SaO_2$ (arterial oxygen saturation): group I$(n=cyanotic,\;SaO_2\;\geq94\%)$ and group II $(acyanotic,\; SaO_2\geq95%)$. Preoperative median hemoglobin level was higher in group I compared to group II (17.5 g/dl vs 15 g/dl). Postoperative follow-up duration ranged from 1 to 94 months (670 patient-month, median: 14 months), and 63 two-dimensional echocardiographic examinations were done during this period. Result: There were no early or late mortality. With regard to RVOT (right ventricular outflow tract) reconstruction, trans-annular patch and RV-PA extracardiac conduit were used in 7 and 3 patients respectively, and all of them belonged to group I. In group I, cardiopulmonary bypass time, aortic cross-clamping time, ICU day, hospital day were significantly longer than in group II, and postoperative inotropic support was significantly greater than in group II. There was no ventricular arrhythmia in both groups, and one patient in group I suffered from atrial arrhythmia, which was resolved spontaneously after tricuspid and pulmonary valve replacement. During follow-up periods, functional class, residual RVOT stenosis and pulmonary regurgitation, tricuspid regurgitation, occurrence of ventricular and atrial arrhythmias were comparable between two groups. Conclusion: In adult ToF patients with severe preoperative cyanosis, more aggressive RVOT reconstruction and careful postoperative care are mandatory. However intermediate-term outcome of this group of patients is comparable to the patients with minimal or no preoperative cyanosis.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.355-361
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• 2006

In this study, effects of influent C/N(COD/Nitrate) ratio and dissolved oxygen(DO) concentration on biological nitrate removal from groundwater were investigated in the fixed-type biofilter. Influent nitrate of 30 mg/L was removed completely by biological denitrification at the C/N ratio of 10 and 4.0, while residual nitrate of 5 mg/L occurred at the C/N ratio of 2.0, which resulted from deficiency of organic electron donor. Furthermore, nitrite was accumulated up to about 5 mg/L as the C/N ratio decreased to 2.0. Increase in DO concentration also inhibited denitrification activity at the relatively high C/N ratio of 5.0, which decreased the nitrate removal efficiency. Although the influent DO concentration was reduced as low as 0.3 mg/L using sodium sulfite($Na_2SO_3$), effluent nitrite was up to 3.6 mg/L. On the other hand, nitrate was completely removed without detection of nitrite at the DO concentration of 0.3 mg/L using nitrogen gas($N_2$) sparging. The organic matter for denitrification in biofilter were in the range from 3.0 to $3.5gSCOD/g{NO_3}^--N$, while utilized these values increased at the high DO concentration of 5.5 mg/L. In addition to the high DO concentration and the low influent C/N ratio, DO control by chemical such as sodium sulfite affected on biological denitrification, which resulted in the reduction of nitrate removal efficiency and nitrite build-up in a biofilter.