• Journal of Korean Society of Environmental Engineers
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• v.31 no.2
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• pp.109-113
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• 2009

This study was performed to investigate the characteristics of nutrient removal of municipal wastewater in membrane bioreactor system. Membrane bioreactor consists of four reactors such as the anaerobic, the stabilization, the anoxic and the submerged membrane aerobic reactor with two internal recycles. The hydraulic retention time (HRT), sludge retention time (SRT) and flux were 6.2 h, 34.1 days and 19.6 L/$m^2$/hr (LMH), respectively. The removal efficiency of $COD_{Cr}$, SS, TN and TP were 94.3%, 99.9%, 69.4%, and 74.6%, respectively. The estimated true biomass yield, specific denitrification rate (SDNR), specific nitrification rate (SNR), specific phosphorus release rate (SPRR) and specific phosphorus uptake rate (SPUR) were 0.653 kgVSS/kgBOD/d, 0.044 $mgNO_3$-N/mgVSS/d, 0.035 $mgNH_4$-N/mgVSS/d, 51.0 mgP/gVSS/d and 5.4 mgP/gVSS/d, respectively. The contents of nitrogen and phosphorus of biomass were 8.86% and 3.5% on an average.

• Journal of Ginseng Research
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• v.28 no.3
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• pp.157-164
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• 2004

The study was conducted to investigate the tissue and chemical characteristics of rusty root epidermal cells. In histological study, the rusty symptoms were frequently observed in the epidermis of ginseng root and to be yellow under microscopic observation. Disks of the epidermal cell tissue of the rusty root were usually 2 and 3 times greater in the number of cell layer and thickness of cell wall than the healthy root, respectively. The color degree of methanol extracts from the rusty root epidermis was 5.5 times higher than that of the healthy root. And the extracts of rust matter in the root epidermis were easily dissolved in polar solvents compared to nonpolar solvents. UV-absorption spectra of methanol extracts in various fractions of phenolics showed a maximum peak between 275∼280 nm. The crude lipids and phenolic compounds such as acid insoluble bound phenolics, acid insoluble esterified phenolics, acid insoluble condensed phenolics, insoluble bound phenolics and free phenolics were also more in the rusty root epidermis than in the healthy one. Fe content in the rusty root epidermis was 2.7 times higher than that of healthy one. It was presumed that the phenolic compounds(precursor of the rusty) in association with lipid and iron in the root epidermis might defence the root when ginseng root was depressed by the unfavorable conditions in soil and/or portions of a root system were subjected to anoxic conditions.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.385-389
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• 2012

In this study, torrefaction of mixed softwood chips under anoxic condition was performed to improve energy density and maintain consistent quality of biomass. Characteristics of torrefied biomass depending on reaction time (30 min) and temperature (240, 260,$280^{\circ}C$) were investigated. Torrefaction of mixed softwood chips significantly improved the heating value compared to that of untreated biomass. As the torrefaction temperature was increased, the carbon content of torrefied biomass increased from 46.55 to 55.73%, while its hydrogen and oxygen contents decreased from 6.00 to 5.87% and from 30.55 to 27.21%, respectively. Most of hemicelluloses and volatile compounds were removed during torrefaction. The highest heating value was 5132 kcal/kg when torrefaction was performed at$280^{\circ}C$ for 30 min. It implied that the heating value increased by 13% compared to that of original biomass. However, the condition of effective torrefaction was at $240^{\circ}C$ for 30 min when weight loss and energy yield was considered.

• KSBB Journal
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• v.24 no.4
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• pp.353-360
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• 2009

This study was accomplished using Anaerobic/Anoxic/Oxic upflow packed-bed column reactors with fixed media and Loop Reactor with fluidized media instead of Oxic reactor. The objectives of this study was to investigate the characteristics of organics, nitrogen and phosphorus removal from sewage with the HRT. The average removal efficiencies of $BOD_5$ and SS increase as increasing the hydraulic retention time (HRT) until 16 h of the HRT, and they were constant over 16 h of the HRT. The removal efficiency of $BOD_5$ in case of packed-bed reactor and Loop Reactor was about 86.6% and 90.9% respectively at 16 h of the HRT. The removal efficiency of SS in packed-bed reactor and Loop Reactor was about 78.0% and 88.2% respectively at 16 h of the HRT. The average removal efficiencies of $COD_{Cr}$ and $COD_{Mn}$ showed similar trends as those of $BOD_5$ and SS. At the HRT of 16 h, the removal efficiency of $COD_{Cr}$ in case of packed-bed reactor and Loop Reactor was 63.5%, 75.2% and that of $COD_{Mn}$ was 60.7%, 73.6% respectively. The average removal efficiencies of T-N and T-P increase as increasing the HRT. The removal efficiencies of T-N and T-P in Loop Reactor were 33.6% and 54.5% respectively at 16 h of the HRT and T-N and T-P were better removed in Loop Reactor. From this result, it was found that the performance of Loop Reactor was much higher than the performance of packed-bed reactor and the optimum HRT was 16 h.

• Proceedings of KOSOMES biannual meeting
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• 2007.05a
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• pp.91-96
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• 2007

Lab scale experimental study was carried out for SBR process, to investigate the effects of influent ship sewage organic compound removal and Bacillus sp. state on design parameters. This process was able to remove nitrogen and phosphorus as well as organic matter efficiently. More than 95% of chemical oxygen demand(COD) were removed. In addition, about 97% of total nitrogen (T-N) was reduced. The total phosphorus(T-P) reduction averaged 93%. The performance load of SBR process was shown to be $0.095kg{\cdot}TOC/m^3{\cdot}day$. The pH was decreased from 8.1 to 7.0 within 30 min and increased to 7.3 at the end of anoxic stage, and these phenomena were explained. The sludge produced in the SBR process is characterized by low generation rate (about $0.36kg{\cdot}MLSS/kg{\cdot}TOC$) and excellent settleability. The number of Bacillus sp. in the SBR was 24.2%, indicating that Bacillus sp. was a predominant species in the reactor.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.1
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• pp.68-74
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• 2010

Since ${NO_3}^-$ is amore favorable electron acceptor than Fe, high ${NO_3}^-$ loads function as a redox buffer limiting the reduction of Fe and following release of ${PO_4}^{3-}$ in flooded paddy soil. The effect ${NO_3}^-$ loaded through irrigation water on Fe reduction and ${PO_4}^{3-}$ release in paddy soil was investigated. Pot experiment was conducted where irrigation water containing 5 or 10 mg N $L^{-1}$ of ${NO_3}^-$ was continuously applied at 1 cm $day^{-1}$, and changes of ${NO_3}^-$, $Fe^{2+}$ and ${PO_4}^{3-}$ concentrations in soil solution at 5 and 10 cm depths beneath the soil surface were monitored as a function of time. Irrigation of rice paddy with water containing 5 mg N $L^{-1}$ of ${NO_3}^-$ led to reduced release of $Fe^{2+}$ and prevented solubilization of P at 5 cm depth beneath the soil surface. And application of irrigation water containing 10 mg N $L^{-1}$ of ${NO_3}^-$ could further suppress Fe reduction and solubilization of P through 10 cm depth soil layer beneath the surface. These results suggest that the introduction of high level ${NO_3}^-$ with irrigation water in rice paddy can strongly limit Fe reduction and P solubilization in root zone soil layer in addition to the excessive supply of N to rice plants.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.9 no.2
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• pp.86-96
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• 1997

In order to investigate the formation of a shallow water front and its relation to water quality distributions, oceanographic measurements were made, and the numerical computations of the Simpson-Hunter stratification parameter log(H/U$^3$) were performed. It is shown from satellite image and hydrographic data that the shallow water front is formed near the northern Kaduk channel, and the stratification parameter log(H/U$^3$) near the front is in a range of 2.0-2.5. Measured COD (Chemical Oxygen Demand) concentrations in offshore region of the front and in the western part of the bay are below 2.0 mg/1. whereas the concentrations in Masan Bay located in the northern inside of the frontal zone are high as 3.0-5.5 mg/1. COD concentrations decrease gradually from Masan Bay toward the offshore due to the dilution by strong water mixing. Anoxic and hypoxic water masses at the bottom layer in summcr occur in the western part of Chinhae Bay and in Masan Bay, and DO (Dissolved Oxygen) concentrations become low with increasing the stratification parameter. DO concentrations outside the front are more than about 4.0 mg/1, whereas the concentrations inside the front are low. The shallow water front plays a significant role for material transport from coastal area to oceanic area, and the frontal region seems to be important physical and chemical boundaries.

• Journal of Wetlands Research
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• v.11 no.1
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• pp.115-121
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• 2009

The hybrid constructed wetland(HCW) as tertiary treatment process of a bio industrial wastewater treatment plant was employed to estimate applications for the reuse of final effluent. Raw wastewater was sequently treated through chemical and biological treatment processes and the biologically treated water was flowed into the HCW. The HCW system was composed of two constructed wetlands connected in series; The one is the aerobic constructed wetland with natural air draft system whose driving force for air supply was the difference between the temperature of the air inside the wetland and the ambient air, and the other is the anaerobic/anoxic constructed wetland. Average influent concentrations of BOD, SS, T-N and T-P in the HCW were 53mg/L, 48mg/L, 34mg/L and 3mg/L, respectively. After being treated at HCW, final effluent concentrations of BOD, SS, T-N and T-P were 2.3mg/L, 1.2mg/L, 7.95mg/L and 0.83mg/L, respectively. Referring to a reuse standard for a sewage wastewater, final effluent could sufficiently be reuse as landscaping, washing or agriculture water. HCW system with the aerobic/anaerobic combined constructed wetland could be achieved a high removal efficiency because each constructed wetland was functionalized to be removed efficiently organics, nitrogen and phosphorus. HCW system could be estimated to be successful application as tertiary treatment process of a various industrial and municipal wastewater.

• Journal of Navigation and Port Research
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• v.29 no.5 s.101
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• pp.475-480
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• 2005

Lab scale experimental study was carried out for SBR process, to investigate the effects of influent ship sewage organic compound removal and Bacillus sp. state on design parameters. This process was able to remove nitrogen and phosphorus as well as organic matter efficiently. More than $92.0\%$ of chemical oxygen demand(COD) were removed. In addition, about $84.0\%$ of total nitrogen (T-N) was reduced. The total phosphorus(T-P) reduction averaged $93\%$. The performance load of SBR process was shown to be $0.095kg{\cdot}TOC/m3{\cdot}day$. The pH was decreased from 8.1 to 7.0 within 30 min and increased to 7.3 at the end of anoxic stage, and these phenomena were explained. The sludge produced in the SBR process is characterized by low generation rate (about $0.36kg{\cdot}MLSS/kg{\cdot}TOC$) and excellent settleability. The number of Bacillus sp. in the SBR was $24.2\%$, indicating that Bacillus sp. was a predominant species in the reactor.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.141-148
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• 2000

In this study, effects of substrates and nitrate on biological phosphorus release in EBPR(enhanced biological phosphorus removal) process were examined using batch test apparatus at anaerobic conditions. The sludge used in this experiments was taken from SBR(sequencing batch reactor) treating swine wastewater at aeration period. Phosphorus release rates obtained with substrates of FSW(fermented swine wastewater), acetate, propionate, domestic wastewater and methanol were 6.19, 5.99, 1.52, 1.2 and $1.03mgP/gVSS{\cdot}hr$, respectively. Those observed with acetate and FSW were 4~5 times greater than those with propionate, methanol and domestic wastewater. Therefore phosphorus release rates were significantly affected by type of substrate added at anaerobic condition. Phosphorus release was greatly affected by concentration of nitrate in anoxic condition. Comparing to acetate, propionate and FSW, phosphorus release was observed after almost completely depletion of nitrate concentration with methanol and domestic wastewater added as substrate. In the cases supplied with acetate, propionate and FSW, phosphorus release rates were less influenced by a nitrate concentration than those with methanol and domestic wastewater.