• Korean Journal of Environmental Agriculture
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• v.16 no.2
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• pp.156-160
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• 1997

The combination of biological wastewater treatment process and membrane separation has many advantages such as better effluent quality and system stability over the conventional biological wastewater treatment process. In this study, direct membrane separation using nonwoven fabric was applied to biological wastewater treatment. A nonwoven fabric module was submerged in the aerated bioreactor. And accumulated biomass in the bioreactor was separated by suction. The system was operated with various condition to investigate pollutant removal efficiencies and flux. After formation of biomass layer on nonwoven fabric surface, a day, the stable effluent water quality was obtained. The flux decreased at a high suction pressure faster than a low pressure. The stable flux was obtained at the pressure of $21{\sim}25cmHg$. In spite of variation of hydraulic retention time, organic loading rate, the removal efficiencies of BOD, $COD_{Cr}$. $COD_{Mn}$ were very high as follows : $95.2%(0.14{\sim}0.97\;BODKg/m^3/day)$, $86.0%(0.17{\sim}1.39\;COD_{Cr}Kg/m^3/day)$, $90.0%(0.097{\sim}0.61\;COD_{Mn}Kg/m^3/day)$.

• Korean Journal of Environmental Agriculture
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• v.13 no.2
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• pp.231-239
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• 1994

A reed-sand-filter system was used to purify swine wastewater economically. Reeds (Phragmites communis Trin) were planted on the sand / gravel bed of a 20/30cm layer depth. After the input of waste-water up to a depth of l0㎝, the effluent was monitored for pollutants on the 1st, 3rd, 5th and 7th day thereafter. As swine wastewater stayed longer, the pollutants in the effluent such as T-N, $PO_4^{3-}$, COD and BOD were removed more effectively. The sand-filter system with reeds showed a superior removal efficiency to that without reeds. Especially in summer, the former showed greater purification rates than the latter, being 30% greater in T-N, 37% in $PO_4^{3-}$, 42% in COD and 30% in suspended solids. The seasonal purification efficiency was in the decreasing order of July, October and April. Reeds took up 40.1g N, 10.8g $P_2O_5$, 38.9g $K_2O$, 2.8g CaO, 2.1g MgO per square meter of the above surface area.

• Applied Biological Chemistry
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• v.20 no.2
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• pp.228-235
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• 1977

The yeast strain was isolated from food industry waste water and its identification and biological characteristics were investigated. The optimum condition for cultivations and its activities for the reduction of B.O.D. on the food industry waste water were also confirmed. The results are as follows; 1) The isolated was identified as Candida curvata. 2) Candida curvata grew well in all of the experimented media, so and it can be regarded as a useful strain in the treatment of food industry waste water. 3) There was only a slight difference in the induction period between sterilized cultivation and unsterilized cultivation. But in the ice cream waste water, the period was considerably longer in unsterilized cultivation. 4) Specific rate of growth of Candida curvata in sugar waste water was 0.50/hr, ice cream waste water 0.50/hr, and beer waste water 1.0/hr. 5) Increasing of innoculum reduced the induction period in unsterilized cultivation. 6) The amount of dried yeast from sugar waste water were $175mg/{\ell}$, ice cream waste water $628mg/{\ell}$, and beer waste water $857mg/{\ell}$. Crude protein content in the dried yeast from sugar waste water were 52%, ice cream waste water 54%, and beer waste water 54%. 7) The rate of BOD reduction in sugar waste water were 49%, ice cream waste water 80%, and beer waste water 64%.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.581-589
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• 2005

Recently, membrane processes have been replacing the conventional processes for waste water treatment to produce better quality of effluent and to meet more stringent regulations because of water shortage. However, using membrane processes for water treatment has confronted with fouling and difficulty in treating dissolved organic pollutants. In this study, membrane process equipped with crossflow microfiltration is combined with coagulation process using alum and PAC to improve permeability and treatment efficiency. The effects of coagulant dosage and optimum membrane operating conditions were investigated from measurement of permeate flow, cumulative volume, total resistance, particle size, dissolved organic pollutant, dissolved aluminium and quality of effluent. Characteristic of PAC coagulation was compared with that of alum coagulation. PAC coagulation reduced membrane fouling because of forming larger particle size and increased permeate velocity and cumulative volume. Less dissolved organic pollutants and dissolved aluminum made decreasing-rate of permeate velocity being lowered. At using $0.2\;{\mu}m$ membrane, cake filtration observed. At using $0.45\;{\mu}m$ membrane, there was floc breakage due to shear stress occurred born circulating operation. It made floc size smaller than membrane pore size, which subsequently to decrease permeate velocity and to increase total resistance. The optimum coagulation dosage was $300{\pm}50\;mg/L$ for both alum and PAC. PAC coagulation was more efficiently used with $0.2\;{\mu}m$ membrane, and the highest permeate flux was in using $0.45\;{\mu}m$membrane. The greatest efficiency of treatment was as follows; turbidity 99.8%, SS 99.9%, $BOD_5$ 94.4%, $COD_{Cr}$ 95.4%, T-N 54.3%, T-P 99.8%.

• Membrane Journal
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• v.15 no.2
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• pp.114-120
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• 2005

The purpose of this study is to obtain practical information about membrane coupled $ A_2O$ system for muncipal wastewater treatment. A flat-plate microfiltration (MF) module with a pore size $0.25\;{\mu}m$ was submerged into the aeration basin and treated water was filtrated through the membrane by continuous suction with low pressure. The system was operated with synthetic wastewater to find operational parameters of internal recycle ratio and maximum MLSS showing best water quality and long-term stability. The internal recycle was defined as type 1 for aerobic to anoxic tank and type 2 for anoxic to anaerobic tank, respectively When the flux was maintained at $0.015\;m^3/m^2/hr$ (15 LMH) with 2Q type 1 internal recycle ratio, the optimal operational setting were 10 internal recycle ratio for type 2 and maximum MLSS of 11,000 mg/L among tested conditions. At this condition, removal efficiencies of BOD, CODcr, T-N and T-P showed $97.3\%,\;94.2\%,\;64.0\%,\;63.0\%$, respectively.

• Journal of Wetlands Research
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• v.22 no.2
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• pp.145-152
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• 2020

Highways are characterized by high non-point pollutant emissions due to high traffic volumes and sections that cause abrupt change in driving speed (i.e. rest stations, ticketing office, etc.). Most highways in Korea were constructed with layers that do not allow adequate infiltration. Moreover, non-point pollution reduction facilities were not commonly installed on domestic highways. This study was conducted to evaluate a facility treating highway runoff and develop a cost-effective design for infiltration facilities by using soil amendment techniques. Performing soil amendment increased the hydraulic retention time (HRT) and infiltration rate in the facility by approximately 30% and 20%, respectively. The facility's efficiency of removing non-point pollutants (Total Suspend Soiled (TSS), Chemical Oxygen Demand(COD), Biological Oxygen Demand(BOD), Total Nitrogen (TN) and Total Phosphorus, (TP) were also increased by 20%. Performing soil amendment on areas with low permeability can increase the infiltration rates by improving the storage volume capacity, HRT, and infiltration area. The application of infiltration facilities on areas with low permeability should comply with the guidelines presented in the Ministry of Environment's Standards for installation of non-point pollution reduction facilities. However, soil amendment may be necessary if the soil infiltration rate is less than 13 mm/hr.

• Journal of Korean Society of Disaster and Security
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• v.13 no.2
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• pp.65-75
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• 2020

The efficiency of sewage treatment was ananlyzed selecting a sewage treatment plant in Gyeonggi-do where A₂O process was applied. Statistical techniques based on the operation data of the sewage treatment were used. The main factors directly affecting the efficiency of the treatment process were analyzed using a GPS-X model. The correlation analysis and one-way ANOVA were performed. The T-N and NH₄⁺-N values of the effluent did not generate statistically significant level (p-value:>0.05) when compared with C/N ration values. Removel of nitrogen components form sewage treatment plants were affected by temperature, HRT, SRT and DO. In the case of BOD, all operating factors were affected, while COD was affecte by factors of HRT, STR and DO. In simulations using GPS-X, the parameters that greatly influence was included the maximum sedimentation rate, the dependent nutrient microbial yield (anoxic), the phosphorus saturation coefficient, the dependent nutrient microbial killing rate, the dependent nutrient microbial maximum growth rate, and the independent trophic microorganisms. The maximum growth rate and the maximum setting rate were identified.

• Korean Journal of Ecology and Environment
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• v.51 no.1
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• pp.86-95
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• 2018

The objective of this study was to describe the development and testing of an initial ecological health assessment model, based on the index of biological integrity (IBI) using fish assemblages, before establishing the final and currently used model for ecological health assessment, conservation and management of freshwater fish in Korea. The initial fish IBI model was developed during 2004~2006 and included 10 metrics, and in 2007 the final IBI 8-metric model was established for application to streams and rivers in four major Korean watersheds. In this paper, we describe how we developed fish sampling methods, determined metric attributes and categorized tolerance guilds and trophic guilds during the development of the multi-metric model. Two of the initial metrics were removed and the initial evaluation categories were reduced from six to four (excellent, good, fair, poor) before establishing the final national fish model. In the development phase, IBI values were compared with chemical parameters (BOD and COD as indicators of organic matter pollution) and physical habitat parameters to identify differences in IBI model values between chemical and physical habitat conditions. These processes undertaken during the development of the IBI model may be helpful in understanding the modifications made and contribute to creating efficient conservation and management strategies for stream environments to be used by limnologists and fish ecologists as well as stream/watershed managers.

• Journal of the Korean GEO-environmental Society
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• v.11 no.5
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• pp.5-13
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• 2010

The research is intended to develop and verify a biological complex soil treatment process to treat and restore soil and groundwater which is contaminated with oil, heavy metals, and nutrients through experiments with the series of treatment process such as bioreactor, rolled pipe type of contact oxidation system(RPS), and chemical processing system. 5 microbial strains were separated and selected through experiment, whose soil purification efficiency was excellent, and it was noted that anion- and nonion-series of complex agent was most excellent as a surfactant for effectively separating oils from soils. Method to mix and apply selected microbes after treating the surfactant in the contaminated soil was most effective. The removal efficiencies of total petroleum hydrocarbon (TPH)-contaminated soil about 5,000mg/L and above 10,000mg/L were approximatly 90.0% for 28 days and 90.7% for 81 days by soil remediation system and the average removal efficiencies of BOD, $COD_{Mn}$, SS, T-N, and T-P in leachate were 90.6, 73.0, 91.9, 73.8, 65.7% by the bioreactor and RPS. The removal efficiency was above 99.0% by chemical processing system into cohesive agents.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.8
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• pp.780-786
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• 2010

The bacterial community structure in biological reactor in wastewater treatment system was investigated by denaturing gradient gel electrophoresis (DGGE) and fluorescent in situ hybridization (FISH). Samples were collected at different three points in wastewater treatment system. Through treatment processes, BOD (biochemical oxygen demand) and COD (chemical oxygen demand) of was removal efficiency was 83.1~98.6%, 67.2~85.2% respectively. Microbial community of aerobic tank and oxic tank were similar but anoxic tank was different (RRP group was increased about tripple) by DGGE and FISH in sludge (2007 October and 2008 January). Samples in 2007 October and 2008 January were dominant ${\alpha}$-Proteobacteria and CF group respectively. Sludge in 2008 April were different comparing former results dominant others as 65~80%. Others group was dominant. Eubacteria by FISH with the probe EUB338 was about $1.7{\sim}7.6{\times}10^9\;cells/mL$. It could be successfully observed bacterial community in biological wastewater system.