• Korean Journal of Ecology and Environment
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• v.39 no.4 s.118
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• pp.489-497
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• 2006

The feasibility of the Natural and Ecological Wastewater treatment System (NEWS) was examined for rural wastewater treatment in Korea. The intermittent trickling biofilter with high hydrophilic filter media was used for pretreatment for suspended solids and organic pollutants. The subsequent constructed wetland with porous granule materials was used for promoting nutrient removal. The results show that the removal efficiencies of the system were high with respect to the water quality parameters except COD. Even if the effluent from the biofilter did not meet the guidelines for wastewater treatment plant effluent in Korea in terms of $BOD_5$ and TN, the final effluent of the system meets the guidelines us to good performance of the constructed wetland. The regression analysis between pollutant loading rate and removal rate indicated that the system could have stable removal for SS, $BOD_5$, TN, and TP in the given influent ranges. The analysis in the winter period indicated that the wetland covered with transparent polycarbonate glass had the statble performance during the winter period dus to increase of temperature inside the wetland without any heating system. With the stable performance, effective poilutant removal, low maintenance, and cost-effectiveness, the NEWS could be considered as an alternative treatment system for decentralized regions and rural communities in Korea.

• Korean Journal of Microbiology
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• v.45 no.4
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• pp.354-361
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• 2009

This study was carried out to develop an effective biocarrier-mediated bioaugmentation technology which will be useful for remediation of the crude oil-contaminated marine sediments. Enrichment of several microbial communities was made from several oil-polluted seashore sites and the two distinctively functional consortia have been successfully selected. These two consortia were grown together and used to manufacture the microbial agents for bioaugmentation of marine sediments polluted with crude oil. The most dominant species in the mixed culture was identified as Alcanivorax borkumensis based on pure culture and DGGE analysis. Bioaugmentation of oil-polluted marine sediments with the microbial agent MA-2 formulated using the mixed culture and biocarriers (activated carbon and minerals) was more effective, especially in combination with an oxygen producing (releasing) compound (ORC). Ninty percent of TPH was removed in the presence of ORC in 35 days while 74% in the absence of ORC. This indicated that the indigenous consortial degraders could be immobilized on the active carbon as a biocarrier to manufacture microbial agents and then effectively bioaugmented for remediation of the oil-polluted sediments.

• The Korean Journal of Ecology
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• v.27 no.6 s.122
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• pp.375-381
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• 2004

We investigate the biological treatment of processed-leachate from SUDOKWON landfill site in Korea by the reed (Phragmites australis)-bed with a continuous flow system. The reed individuals showing superior growth in processed-leachate experiment were selected among the reeds of thirteen natural habitats by means of the comparisons between the removal rates of nutrient salts, eco-physiological responses and growth. The reed-beds (combination of the reed individuals showing superior growth with helper microorganisms) were continuously supplied with processed-leachate. We monitored the effluents that passing through the reed-beds during the experiment period. After five weeks, analysis results of effluent from each reed-bed were as follows; chromaticity, total nitrogen, total phosphorus, biological oxygen demand, chemical oxygen demand, total dissolved solid and salinity decreased $29.5{\sim}36.9\%,\;49.4{\sim}67.2\%,\;42.1{\sim}94.6\%,\;74.5{\sim}88.8\%,\;15.6{\sim}20.8\%,\;17.5{\sim}35.4\%\;and\;15.3{\sim}34.7\%$, respectively. These results represented the substantial improvement of water-quality after passing through reed-bed in a continuous flow system.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.4
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• pp.179-185
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• 2005

Polycyclic aromatic hydrocarbons (PAHs) are a kind of toxic environmental pollutants and has been accumulated usually in marine sediments. Due to their potential hazardous to human, removal of PAHs from environments has been great concern. In the present study, the effect of microbial inoculation and the supplementation of mixed form cyclodextrin (M-CD) was assessed in the pre-sterilized or nonsterilized microcosms for optimizing operational conditions for ex situ bioremediation of sediments contaminated by PAHs. Activity of electron transport system (ETSA) was increased by the addition of M-CD regardless of inoculation of microorganisms in microcosms without sterilization. The degradation rate of PAHs in sterilized microcosms was app. 9-20% by the inoculation of single strain and 24-37% by the inoculation of microbial consortium supplemented with 1% M-CD, respectively. The degradation was not observed in microcosms without sterilization under the same conditions. The proportion of inoculated microorganisms also decreased in nonsterilized microcosms. Signals of inoculated bacteria were decreased to detection limit after 2 days in the microcosms without M-CD. In conclusion, microbial inoculation with appropriate carbon sources and removal of natural flora and grazers are required for the efficient ex situ bioremediation of sediments contaminated by PAHs in bioslurry reactor.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.4
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• pp.311-318
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• 2010

U. S. NRC Regulation Guide 1.52 regulating ESF ACS in nuclear power plants has been revised to revision 3. To apply reduction of operability test time, allowance of alternative challenge agents for in-place leak test of HEPA filters, and upgrade of Methyl Iodide penetration acceptance criterion in activated carbon performance test suggested in Reg. Guide 1.52(Rev.3) on Yonggwang units 5 and 6 ESF ACSes, technical feasibility study was carried out with on-site experiments as well as experiments with a lab-scale model. It was confirmed that the moisture in the system returned to the level before the test in 1 or 4 days even though the moisture was removed during the operability test lasting more than 10 hours. Therefore, it is appropriate to perform monthly operability test in 15 minutes just long enough to check the operability of equipment. To change challenge material for in-place HEPA filter leak test, size of aerosol, production rate, and leak detection capability were compared for DOP and PAO. It was concluded that PAO can be substituted for DOP in nuclear power plants. The upgrade of Methyl Iodide penetration acceptance criterion from 0.175 % to 0.5 % in active carbon filter bed deeper than 4 inches was to conform to the change of activated carbon performance test method to ASTM D3803(1989). It was confirmed that Methyl Iodide penetration acceptance criterion of 0.5 % under $30^{\circ}C$, relative humidity 95 % condition was conservatively good enough for testing performance of active carbon insitu. The licence change of Yonggwang units 5 and 6 has been completed based on this study.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.1-7
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• 2005

Tidal flats have been regarded to carry out transformation and removal of land-derived organic matter, and this purifying capability of organic matter by tidal flats is one of very important reasons for their conservation. However, integral biogeochemical studies on production and decomposition of organic matter by benthic microbes in tidal flats have been absent in Korea, although the information is indispensable to quantification of the purifying capability. Our major goals in this multidisciplinary research were to understand major biogeochemical processes and rates mediated by diverse groups of microbes dominating material cycles in the tidal flats, and to assess the contribution of benthic microbes to removal of organic matter and nutrients in the tidal flats. Our study sites were Ganghwa and Incheon north-port tidal flats that had been regarded as naturally well reserved and organically polluted, respectively. Our research group measured over 3 years primary production, biomass and community structure of primary producers, abundance and production of bacteria, enzyme activities, distribution of protozoa and protozoan grazing rates, rates of denitrification and sulfate reduction, early sediment diagenesis, primary production and respiration based on oxygen microelectrode. We analyzed major features of each biogeochemical process and their interactions. The results are compiled in the following articles in this special issue: An (2005), Hwang and Cho (2005), Mok et at. (2005), Na and Lee (2005), Yang et at. (2005), and Yoo and Choi (2005).

• Horticultural Science & Technology
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• v.33 no.4
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• pp.605-617
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• 2015

The ultimate goal of this research is to develop a botanical biofiltration system that combines a green interior, biofiltering, and automatic irrigation to purify indoor air pollutants according to indoor space and the size of biofilter. This study was performed to compare the stability of air flow characteristics and removal efficiency (RE) of fine dust within a wall-typed (vertical) botanical biofilter depending on humidifying cycle and to investigate RE of volatile organic compounds (VOCs) by the biofilter. The biofilter used in this experiment was designed as an integral form of water metering pump, water tank, blower, humidifier, and multi-level planting space in order to be suitable for indoor space utilization. As a result, relative humidity, air temperature, and soil moisture content (SMC) within the biofilter showed stable values regardless of three different humidifying cycles operated by the metering pump. In particular, SMCs were consistently maintained in the range of 27.1-29.7% during all humidifying cycles; moreover, a humidifying cycle of operating for 15 min and pausing for 45 min showed the best horizontal linear regression (y = 0.0008x + 29.09) on SMC ($29.0{\pm}0.2%$) during 120 hour. REs for number of fine dust (PM10) and ultra-fine dust (PM2.5) particles passed through the biofilter were in the range of 82.7-89.7% and 65.4-73.0%, respectively. RE for weight of PM10 passed through the biofilter was in the range of 58.1-78.9%, depending on humidifying cycle. REs of xylene, ethyl benzene, total VOCs (TVOCs), and toluene passed through the biofilter were in the range of 71.3-75.5%, while REs of benzene and formaldehyde (HCHO) passed through the biofilter were 39.7% and 44.9%, respectively. Hence, it was confirmed that the wall-typed botanical biofilter suitable for indoor plants was very effective for indoor air purification.

• Economic and Environmental Geology
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• v.48 no.6
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• pp.491-500
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• 2015

Batch experiments were performed to determine the feasibility of the surfactant-enhanced soil washing process at various washing conditions for the Kuwait soil seriously contaminated with the crude oil. The soil was sampled at a dried oil pond in Kuwait and its average TPH concentration was 223,754 mg/kg, which was too high to apply the conventional remediation process. Nine commercialized non-ionic surfactants were used for the batch experiment to measure the surfactant solubility for the crude oil because it was reported that they have worked for the soil remediation. Among them, three surfactants having high crude oil solubility were used for the soil washing experiment. From the result of batch experiment, 5% TritonX-100 washing solution showed the highest TPH removal efficiency (67%) for the crude oil contaminated soil. However, because the residual TPH concentration in the washed soil was still higher than the clean-up level in Kuwait (10,000 mg/kg), the repeated soil washing was performed. After five washings with 2% surfactant solution, the cumulative TPH removal efficiency was higher than 96% and the residual TPH concentration in the soil went down below the clean-up level. To measure the desorption capacity of TritonX-100 remained in the soil after the soil washing, the silica beads and the soil were washed five times with 2% TritonX-100 surfactant solution and then they were washed again with distilled water to detach the surfactant adsorbed on beads or soil. After five washings with surfactant solution, 7.8% and 19.6% of the surfactant was adsorbed on beads and soil, respectively. When additionally washed with distilled water, most of the residual surfactant were detached from beads and only 4.3% of surfactant was remained in soil. From the results, it was investigated that the surfactant-enhanced soil washing process with TritonX-100, Tergitol S-15-7, and Tergitol S-15-9 has a great capability for the remediation of the Kuwait soil seriously contaminated by crude oil (more than 220,000 mg/kg).

• The Journal of Engineering Geology
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• v.19 no.3
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• pp.295-306
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• 2009

The risk assessment of groundwater and soil in Sasang industrial complex in Busan Metropolitan City was carried out in order to estimate risks to human health and the environment. The carcinogenic risk (CR) of receptors to soil and air was not identified. However, the CRs for TCE and PCE were 6.7E-6 and 1.0E-5, respectively. Hazard quotient (HQ) and hazard index (HI) did not appear through air exposure pathways. Yet the HQ and HI of soil were 3.4E-5 and 5E-5, respectively, and lower than the critical value (1.0). On the contrary, HQ and HI with respect to groundwater were calculated as 0.7 (not hazardous) and 1.4 (hazardous). The constituent reduction factor (CRF) for TCE in the study area was determined as 2.5, and thus remediation work is demanded. As a result of sensitivity analysis for 18 exposure factors, eight exposure factors (life time of carcinogens, age, body weight, exposure duration, exposure frequency, dermal exposure frequency, water ingestion rate, and soil ingestion rate) varied with the variation of risk.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.56-68
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• 2005

We measured nitrate and other nutrients in sediment pore waters retrieved from three sites at the southern upper-tidal flats of the Ganghwa Island. Denitrification rate is estimated by applying a simple 1-D model to the nitrate profiles. Results from Jangwha and Dongmak sites are $7.8{\sim}9.4{\times}10^{-7}{\mu}mol{\cdot}cm^{-2}{\cdot}sec^{-1}$, and $1.4{\sim}3.6{\times}10^{-7}{\mu}mol{\cdot}cm^{-2}{\cdot}sec^{-1}$, respectively. Rates are comparable to those reported around the world in an order of magnitude. Denitrification was lower in summer. The rates were about 1.5 times higher at site where the surface sediments consist of relatively coarser particles. This implies that particle size would control the reactant supply to the subsurface sediment. One may claim the denitrification as an evidence of the biogeochemical purification function of tidal flat. However, the purification seems not a general attribute of a tidal flat when whole system is scrutinized by a thermodynamic criterion. Currently the term 'tidal flat' is used when describing the diverse coastal wetlands such as salt marshes, sandy tidal flats and muddy tidal flats, which exhibit quite different ecological functions. Thus it is worthy of mentioning that the classification of coastal wetlands on the basis of sedimentological characteristics and biogeochemical functions should facilitate our understanding.