• Journal of Korean Society of Water and Wastewater
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• v.27 no.6
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• pp.779-785
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• 2013

This study investigated the applicability of a two step microfiltration(MF) and reverse osmosis(RO) membrane system for reuse of tunnel wastewater. In this two step process, the MF system first treated only micropollutants in tunnel wastewater such as suspended solids(SS) and heavy metals, achieving less than 0.2 NTU turbidity, less than 1.1 mg/L chemical oxygen demand($COD_{Mn}$) and less than 0.8 mg/L total manganese(Mn). The RO system then removed over 95 % of the remaining pollutnats and particles, resulting in less than 0.02 NTU turbidity, less than 0.5 mg/L chemical oxygen demand($COD_{Mn}$), less than 0.04 mg/L total nitrogen(T-N) and less than 0.01 mg/L total phosphorus(T-P). In particular, addition of an RO system could lead to markedly reduced high salt concentrations in tunnel wastewater, approaching almost zero. Thus, reclaimed water using the combined membrane system could satisfy current South Korean regulations concerning wastewater reuse(turbidity ${\leq}2.0$ NTU; T-N ${\leq}10mg/L$; T-P ${\leq}0.5mg/L$; Salinity ${\leq}250mg{\cdot}Cl/L$).

• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.573-576
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• 2006

The efficacy of integrated ozone oxidation-biodegradation treatment was examined in the treatment of petrochemical wastewater with a special focus on the overall treatment time. When raw wastewater with chemical oxygen demand(COD) of 70-80 mg/L was oxidized by ozone, approximately 20% of initial COD was removed in less than 1.5 min at a dosing rate of 400 mg $O_3/L{\cdot}h $. No further decrease in COD was observed for the extended ozone treatment up to 30 min. Biological treatment alone showed a rapid reduction of COD to 40-50 mg/L, subsequently resulting in the decreased rate of COD removal. Pre-treatment by ozone before biological treatment did not significantly affect the specific rate of COD removal in a biological treatment. When ozone oxidation followed biological treatment, the extent of COD removal by ozone oxidation was greater compared to that of biologically-treated wastewater for a shorter time. Taken together, it was decided that the biological treatment time could be reduced if the treatment processes of concern will be properly arranged.

• Journal of Microbiology and Biotechnology
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• v.24 no.7
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• pp.987-997
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• 2014

The mature landfill leachate, which is characterized by a high concentration of ammonia nitrogen ($NH_3$-N) and humic acid (HA), poses a challenge to biotreatment methods, due to the constituent toxicity and low biodegradable fraction of the organics. In this study, we applied bioaugmentation technology in landfill leachate degradation by introducing a domesticated $NH_3$-N and HA resistant bacteria strain, which was identified as Bacillus cereus (abbreviated as B. cereus Jlu) and Enterococcus casseliflavus (abbreviated as E. casseliflavus Jlu), respectively. The isolated strains exhibited excellent tolerant ability for $NH_3$-N and HA and they could also greatly improved the COD (chemical oxygen demand), $NH_3$-N and HA removal rate, and efficiency of bioaugmentation degradation of landfill leachate. Only 3 days was required for the domesticated bacteria to remove about 70.0% COD, compared with 9 days' degradation for the undomesticated (autochthonous) bacteria to obtain a similar removal rate. An orthogonal array was then used to further improve the COD and $NH_3$-N removal rate. Under the optimum condition, the COD removal rate in leachate by using E. casseliflavus Jlu and B. cereus Jlu increased to 86.0% and 90.0%, respectively after, 2 days of degradation. The simultaneous removal of $NH_3$-N and HA with more than 50% and 40% removal rate in leachate by employing the sole screened strain was first observed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.6
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• pp.619-626
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• 2014

In this paper, it was constructed the halophyte Mesocosm experimental which was used tidal flat and dredged sediment as a substrate material. Depending on the vegetation and substrate material of Mesocosm, Mesocosm A(tidal flat sediment + Salicornia herbacea), Mesocosm B (only dredged sediment), Mesocosm C(dredged sediment + Salicornia herbacea). Monitoring was carried out of Warter quality factots(Chemical Oxygen Demand(COD), Total Nitrogen(T-N), Total Phosphorus(T-P), water temperature, salinity), Sediment factors(Chemical Oxygen Demand(COD), Total Nitrogen(T-N), Total Phosphorus(T-P)) and growth of Salricornia herbacea. Habitat Stability Index of vegetation was calculating by using the monitoring results. HSI of Mesocosm C was calculated from 0.87 to 0.95 as compared to the relatively high HSI in Mesocosm A, it was evaluated to be able to be used in the restoration and construction of the coastal salt marsh with dredged sediment.

• Environmental Engineering Research
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• v.19 no.4
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• pp.355-361
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• 2014

The wastewater treatment with a two-phase expanded granular sludge bed (EGSB) system for anaerobic degradation of acetate, benzoate, terephtalate and p-toluate from purified terephtalic acid (PTA) production was studied. The feasibility and effectiveness of the system was evaluated in terms of organic oxidation by chemical oxygen demand (COD), gas production, bacterial adaptability and stability in the granular sludge. Average removal efficiencies 93.5% and 72.7% were achieved in the EGSB reactors under volumetric loading rates of $1.0-15kg-COD/m^3/day$ and terephtalate and p-toluate of 351-526 mg/L, respectively. Gas production reached total methane production rate of 0.30 L/g-COD under these conditions in the sequential EGSB reactor system. Higher strength influent COD concentration above 4.8 g-COD/L related to field conditions was fed to observe the disturbance of the EGSB reactors.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.626-631
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• 2005

Monitoring data from agricultural reservoirs throughout the country were analyzed to evaluate the limiting factor for algal growth and correlationship between Chl-a, total phosphorus (TP), total nitrogen (TN), and chemical oxygen demand (COD). It was used for the analysis to monitored data of 394 reservoirs such as TP, TN, Chl-a, and COD from 1999 to 2003. This study analyzed water quality items in terms of areas, seasons. It turned out that phosphorus in agricultural reservoirs (about 80%) was dominant limiting factor for algal growth. Therefor, it appears that the appropriate managements of phosphorus in the agricultural watershed are crucial to prevent excessive on algal growth. Generally, there is correlation between Chl-a and TP while Chl-a do not have effect on TN. Also, Chl-a have influence on COD. This study could be used beneficially for water quality management of agricultural reservoirs and related water quality modeling.

• Advances in environmental research
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• v.5 no.3
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• pp.169-178
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• 2016

This study aimed at determining the treatability of high-strength wastewater (chemical oxygen demand, COD>4000 mg/L) using combined anaerobic-aerobic granular sludge in lagoon systems. The lagoon systems were simulated in laboratory-scale aerated and non-aerated batch processes inoculated with dried granular microorganisms at a dose of 0.4 g/L. In the anaerobic batch, a removal efficiency of 25% was not attained until the 12th day. It took 14 days of aerobic operation to achieve sCOD removal efficiency of 94% at COD:N:P of 100:4:1. The best removal efficiency of sCOD (96%) was achieved in the sequential anaerobic-aerobic batch of 12 days and 2 days, respectively at COD:N:P ratio of 200:4:1. Sequential anaerobic-aerobic treatment can achieve efficient and cost effective treatment for high-strength wastewater in lagoon systems.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.4
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• pp.819-827
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• 2013

Water quality has been considered to be one of sanitation standard operating procedures (SSOP) for hazard analysis critical control points (HACCP) application in aquaculture farms. This study was conducted to evaluate a hazard caused by water used in aquaculture farm of rainbow trout. The water quality was analyzed to investigate both physiochemical and bacteriological level in water samples collected from aquaculture farm of rainbow trout, Oncorhynchus mykiss. No significant difference were observed on water temperature and pH from season to season. However, the levels of dissolved oxygen were decreased as the outside temperature was increased, even if the levels were adequate for aquaculture. Also, other physiochemical analysis including biochemical oxygen demand (BOD), chemical oxygen demand (COD) and suspended solid (SS) revealed that the waters for aquaculture analyzed in this study was suitable for rainbow trout aquaculture. The bacterial analyses were also revealed that the waters for aquaculture were met to both coliform group (<18 MPN/100mL) and viable cell count (<100 CFU/mL). However, some of waste waters from aquaculture farms showed higher levels of BOD and COD than those of waste water standard (<2 ppm), suggesting that regular cleaning of fish tank and precipitation tank is needed.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.355-358
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• 2002

In this study, we have tried to find the maximum microbial efficiency at the various dissolved oxygen (DO) concentration conditions in the treatment of pharmaceutical wastewater. Experiments of activated sludge process were performed to examine the relation between microbial activity and DO concentration in a continuous bioreactor. The reduction rate of COD (chemical oxygen demand) was low at the DO concentration between 0 ppm and 1.0 ppm, but it went higher and showed maximum between 1.5 ppm and 3.0 ppm. Then the COD reduction rate was quickly decreased above the DO concentration of 3.0 ppm.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.4
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• pp.207-216
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• 2014

Total organic carbon (TOC) is an important indicator used as an direct biological index in the research field of the marine carbon cycle. It is possible to produce the sufficient TOC estimation data by using the Chemical Oxygen Demand(COD) data because the available TOC data is relatively poor than the COD data. The outlier detection and treatment (removal) should be carried out reasonably and objectively because the equation for a COD-TOC conversion is directly affected the TOC estimation. In this study, it aims to suggest the optimal regression model using the available salinity, COD, and TOC data observed in the Korean coastal zone. The optimal regression model is selected by the comparison and analysis on the changes of data numbers before and after removal, variation coefficients and root mean square (RMS) error of the diverse detection methods of the outlier and influential observations. According to research result, it is shown that a diagnostic case combining SIQR (Semi - Inter-Quartile Range) boxplot and Cook's distance method is most suitable for the outlier detection. The optimal regression function is estimated as the TOC(mg/L) = $0.44{\cdot}COD(mg/L)+1.53$, then determination coefficient is showed a value of 0.47 and RMS error is 0.85 mg/L. The RMS error and the variation coefficients of the leverage values are greatly reduced to the 31% and 80% of the value before the outlier removal condition. The method suggested in this study can provide more appropriate regression curve because the excessive impacts of the outlier frequently included in the COD and TOC monitoring data is removed.