• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.727-735
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• 2007

The use of water by cities is increasing owing to industrialization, the concentration of population, and the enhancement of the standard of living. Accordingly, the amount of waste water is also increasing, and the degree of pollution of the water system is rising. In order to solve this problem, it is necessary to remove organisms and suspended particles as well as the products of eutrophication such as nitrates and phosphates. This study developed a high-end treatment engineering solution with maximum efficiency and lower costs by researching and developing a advanced treatment engineering solution with the use of Biosorption. As a result, the study conducted a test with a $50m^3/day$ Pilot Scale Plant by developing treatment engineering so that only the secondary treatment satisfies the standard of water quality and which provided optimal treatment efficiency along with convenient maintenance and management. The removal of organisms, which has to be pursued first for realizing nitrification during the test period, was made in such a way that there would be no oxidation by microorganisms in the reactor while preparing oxygen as an inhibitor for the growth of microorganism in the course of moving toward the primary settling pond. The study introduced microorganisms in the endogeneous respiration stage to perform adhesion, absorption, and filtering by bringing them into contact with the inflowing water with the use of a sludge returning from the secondary settling pond. Also a test was conducted to determine how effective the microorganisms are as an inner source of carbon. The HRT(Hydraulic Retention Time) in the nitrification tank (aerobic tank) could be reduced to two hours or below, and the stable treatment efficiency of the process using the organisms absorbed in the NAR reactor as a source of carbon could be proven. Also, given that the anaerobic condition of the pre-treatment tank becomes basic in the area of phosphate discharge, it was found that there was excellent efficiency for the removal of phosphate when the pre-treatment tank induced the discharge of phosphate and the polishing reactor induced the uptake of phosphate. The removal efficiency was shown to be about 94.4% for $BOD_5$. 90.7% for $COD_{Cr}$ 84.3% for $COD_{Mn}$, 96.0% for SS, 77.3% for TN, and 96.0% for TP.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.1
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• pp.89-99
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• 2006

The growth and biomass of reeds(Phragmites australis) growing in a subsurface treatment wetland system were investigated from April 2003 to October 2003. Nitrogen(N) and phosphorous(P) concentrations in above-ground(AG) and below-ground(BG) tissues of reeds were examined and the removal rate of N and P by reeds were analyzed. The system, 29 m in length, 9 m in width and 0.65 m in depth, was constructed in June 2001 on a floodplain in the down reach of the Kwangju Stream in Korea in order to purify polluted water of the stream. A bottom layer of 45 cm in depth was filled with crushed granites(15~30 mm in diameter) and a middle layer of 10 cm in depth was filled with pea pebbles(10 mm in diameter). An upper layer of 5 cm contained course sand. Reeds were transplanted on the surface of the system, which were dug out of natural wetlands, and their shoots were trimmed 40 cm in height. The height and density of the shoots averaged 237.7 cm and 244.0 shoot/$m^2$, respectively, when the reeds grew fully. The maximum biomass of AG and BG tissues were 1,964 and 1,577 g/$m^2$, respectively, and the AG : BG ratio of biomass was 1.26. Mean AG and BG dry weights were recorded as 1,355 and 748 g/$m^2$, respectively. The AG and BG tissue concentrations of N averaged 12.37 and 10.01 mg/g, respectively, and those of P 2.37 and 2.03 mg/g, respectively. Inflow to the system averaged 40 $m^3$/day. The concentrations of total nitrogen(T-N) in influent and effluent were 8.4 mg/L and 3.2 mg/L, respectively, and those of total phosphorous(T-P) were 0.73 and 0.38 mg/L, respectively. The total removal of T-N and T-P by the system during the investigation period averaged 140.2 and 9.7 g/$m^2$, respectively, and the total uptake of N and P by the reeds were calculated as 24.39 and 4.73 g/$m^2$, respectively. Average removals of about 17% of N and about 49% of P by reeds were recorded. The N and P concentrations in AG tissues were significantly different among the three zones of the system:near to inflow(St1), in the middle of system(St2), and near to outflow(St3). The N and P concentrations in BG tissues were also significantly different among St1, St2 and St3. N and P concentrations in AG and BG tissues of reeds growing in St1 were higher than those in St2 and St3. The height and density of shoots of reeds in St1 were larger than those in St2 and St3. Significant amounts of N and P in the influent were taken up by reeds in St1.

• Journal of Wetlands Research
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• v.14 no.1
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• pp.121-130
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• 2012

This study is to investigate the removal rates of nutrient in water, the biomass of water plants, and the total amounts of T-N and T-P uptakes by water plants to evaluate the ecological characteristics of the constructed wetland for treatment of livestock wastewater in Yangji-ri, Nonsan-si from June through November 2011. During the experimental period, the monthly plant biomass of constructed wetland in July were the highest as 669.4 kg, while the lowest in November as 200.1 kg. The research showed that the average nitrogen and phosphorus contents in aboveground and underground biomass of Phragmites australis were $21.9{\pm}0.6{\sim}32.1{\pm}1.5mg/g$, $15.1{\pm}5.5{\sim}24.9{\pm}5.7mg/g$, $1.5{\pm}0.3{\sim}2.4{\pm}0.2mg/g$ and $1.6{\pm}0.6{\sim}2.5{\pm}0.6mg/g$, respectively. The maximum amount of T-N and T-P uptake by Phragmites australis were 28.0 kg in July and 2.5 kg in June, respectively, while the minimum amount of T-N and T-P uptake by Phragmites australis were 9.7 kg and 0.7 kg in November, respectively. The removal rates of T-N and T-P in constructed wetland for treating livestock wastewater were 23.0 % and 59.1 %, respectively. The results of this study is expected to deduce the circulation of contaminants and nutrient in the wetland afterwards.

• Korean Journal of Environmental Biology
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• v.17 no.1
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• pp.117-124
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• 1999

Nutrients removal by water hyacinth, Eichhornia crassipes (Mart.) Solms from nutrient enriched waters and swinery wastewater were evaluated. The contents of nitrogen and phosphorus of dried water hyacinth increased from 1.4 to 3.3% and 0.21 to 0.80% when water hyacinth available N and P in the culture medium were increased from 0.7 to 5.0 mgN/1 and 0.06 o 1.5 mgP/l. respectively. Maximum N and P contents were found to be 4.1 and 0.90%, respectively. The significant relationship was observed between the standing crop of water hyacinth and the biomass yield per unit area and time. Biomass yield increased gradually until standing crop reached 15 kg wet wt./m$^2$, and then rapidly decreased. The high biomass yield of up to 0.5 kg/m$^2$/day was obtained in the range of 7 to 20 kg/m$^2$of standing crop. The potential removal rates of N and P by the water hyacinth during summer were found to be 2,250 to 2,710 mgN/m$^2$/day and 570 to 595 mgP/m$^2$/day, respectively, when 15 kg/m$^2$in standing crop and nutrient concentrations of culture medium were ranged from 1.24 to 6.2 mgP/1 and 3.2 to 32.5 mgN/1, respectively, Inorganic N and P concentrations of swinery wastewater were in the range of 82 to 121 mgN/1 and 22 to 79 mgP/1, respectively. Nitrogen and P removal rates of water hyacinth cultured in swinery wastewater were found to be in the ranges of 2,000 to 2,600 mgN/m$^2$/day and 157 to 254 mgP/m$^2$/day, respectively, at 10 times diluted water of swinery wastewater.

• Journal of Environmental Impact Assessment
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• v.28 no.6
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• pp.549-555
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• 2019

The purpose of this study is to ensure optimal operating conditions for improving the removal efficiency of phosphorus (P) and nitrogen (N) that are the causative agents of eutrophication by utilizing functional media. The main ingredients of the functional media used in this study are Si, Al, and Fe, SiO₂, KAlSiO₃O₈, Al₂O₂·2SiO₂O, H₃Al₂Si₂O₉, Fe₃O₄O), and berylite. To identify the maximum efficiency of the filtration process, the processing efficiency experiment was carried out according to flow method, velocity, and thickness of residual media. The flow method carried out two experiments, 50 m/day, 100 m/day, 150 m/day, 200 m/day, 250 m/day, and 20 cm, 40 cm, 50 cm, 60 cm, 80 cm of lead depth. Experiments have shown that SS, T-N, and T-P all showed higher elimination efficiency of the upflow current conditions than the downflow current conditions, and that the processing efficiency of the linearity is the highest at SS 50 m/day, T-N 150 m/day and T-P 100 m/day. In addition, the analysis of the removal efficiency according to the residual thickness showed that SS, T-N, and T-P all showed the highest efficiency at 60 cm. In addition, the analysis of the removal efficiency according to the residual thickness showed that SS, T-N, and T-P all showed the highest efficiency at 60 cm. It is considered desirable to set the top-down flow conditions and residual thickness of 60 cm and adjust the velocity of the line according to the target media for removal.

• KSBB Journal
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• v.14 no.5
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• pp.585-592
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• 1999

This study was aimed to enhance the Fe(II) oxidation rate using immobilized cells of Thiobacillus ferroxidans. For this purpose, a medium for the minimization of jarosite formation was developed first. Secondly, cell immobilization in celite beads was carried out. And then, repeated-batch and continuous operatons of Fe(II) oxidation by using immobilization cells were performed. In a series of flask cultures, three types of media were tested: media with a much lower salt concentration than that of the 9K medium; media which contained different nitrogen sources from that of the 9K medium, that is $(NH_4)_2HPO_4$, $NH_4Cl and HNO$_3$; media which contained $(NH_4)_2HPO_4$ as nitrogen and phosphate source, but without $K_2HPO_4$ as nitrogen and phosphate source in the 9K medium. As a result, the M16 medium which contained 3 g/L of $(NH_4)_2HPO_4$ as nitrogen and phosphate source was found to be the optimal one. It sustained good cell growth allowing no jarosite formation. In the repeated-batch operations, the rate of Fe(II) oxidation gradually increased to reach a maximum value as the batch was repeated. As a result of repeated-batch operations. a maximum Fe(II) oxidation rate was 2.33 g/L . h. In the continuous operations, the iron oxidation rate could be increased to 2.14 g/L .h at a dilution rate of 0.25 $h^{-1}$ which is greater than the maximum specific growth rate (0.12 $h^{-1}$) of the bacteria.

• Membrane Journal
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• v.23 no.3
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• pp.226-236
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• 2013

The effect of $N_2$ back-flushing period (FT) and time (BT) was compared with the previous result used PES (polyethersulfone) beads loaded with titanium dioxide photocatalyst in hybrid process of alumina microfiltration and PP (polypropylene) beads coated with photocatalyst in viewpoints of membrane fouling resistance ($R_f$), permeate flux (J), and total permeate volume ($V_T$). The reason of nitrogen back-washing instead of the general air back-washing method is to minimize the possible effect of oxygen included in air on water quality analysis. As decreasing FT, $R_f$ decreased and J and $V_T$ increased. Treatment efficiency of dissolved organic matters (DOM) was 82.0%, which was the higher than 78.0% of the PES beads result. This means that PP beads coated with photocatalyst was the more effective than PES beads loaded with photo-catalyst in the DOM removal. As increasing BT, the final $R_f$ decreased and the final J increased, but $V_T$ was the maximum at BT 15 sec. The average treatment efficiency of turbidity did not have any trend as changing BT. As BT increasing from 6 sec to 30 sec, the treatment efficiency of DOM increased 11.8%, which was a little higher than the result of PES beads.

• Korean Journal of Environmental Agriculture
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• v.33 no.2
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• pp.111-120
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• 2014

BACKGROUND: This study was conducted to investigate the levels of pesticide residues in fruits and to assess their risk to human health. METHODS AND RESULTS: Monitoring of 215 samples of fruits collected from local markets in incheon during 2013 was performed. 259 pesticides were analyzed by multi-residue method and Quick, Easy, Cheap, Effective, Rugged, and safe/Mass/Mass(QuEChERS/MS/MS) method using Gas Chromatography-Electron Capture Detector/Nitrogen Phosphorus Detector(GC-ECD/NPD), GC-MS, LC(Liquid Chromatography-Mass/Mass(LC-MS/MS) and High Performance Liquid Chromatography-Photodiode Array/Fluorescence Detector(HPLC-PDA/FLD). In 56.3% of the samples detected pesticide residues and were not found to exceed Maximum Residue Limits(MRL). The highest detected samples were found in citrus fruits(83.9%). Among the detected compounds, carbendazim(13.1%), imazalil (11.7%), thiabendazole(10.7%) and fludioxonil(9.8%) were frequently found in fruits. A risk assessment of pesticide residues in fruits was performed by calculating Estimated Daily Intake(EDI) and Acceptable Daily Intake(ADI). Also, we were evaluated removal efficiency of pesticide residues by washing and peeling. The removal efficiency of pesticide residues in citrus and tropical fruits by peeling processes were 91.6%. After the washing process, the removal rates were 43.1%(Cherry, Grape, Blueberry). CONCLUSION: The level of pesticide residues in fruits was within the MRL. The range of %ADI values was from 0.00011 to 0.98795%. The process of washing or peeling reduces the level of pesticide residues. The results of this research concluded that the detected pesticides are not harmful to human being.

• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.145-151
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• 2000

A porous silicate material named as CellCaSi was tested for the removal of microalgae in the water sample from a eutrophic pond. The effects of the CellCaSi on water qualities were investigated on the basis of both the particle size (under 1, 2,and 4 mm) and the added amount (0, 1, 5, and 10 g/l) of the CellCaSi. The removal efficiency of chlorophyll-a was highest at 79% by the addition of 10 g/l of the CellCaSi (under 1 mm) at day 3 after treatment. That is, the removal efficiency of chlorophyll-a by the CellCaSi increased with smaller particle size and more added amount. The dominant species, Chlorella ellipsoidea, was not changed by the addition of the CellCaSi, but the species number and standing crop of the algae diminished. Total nitrogen concentration was not changed much by the addition of the CellCaSi, whereas total phosphorus concentration was reduced. pH and turbidity were not changed by the addition of the CellCaSi, whereas conductivity showed a high correlation with the amount of added CellCaSi ($Y\;=\;29.2 {\cdot}X+306$, $r^2\;=0.984$). Therefore, it seems to be necessary to limit the amount of the CellCaSi under 6.6 g/1 in consideration of a registered maximum conductivity of $500\;{\mu}mhos/cm$ for raw and potable waters.

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.129-135
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• 2011

The possibility of nutrient removal during Scenedesmus sp. growth in Lake Paldang, Geongan cheon stream, and the outflow from a wastewater treatment system was examined. Scenedesmus sp. grew well in Lake Paldang water when total nitrogen (TN) and total phosphorus (TP) values were 1.9 and 0.02 mg $L^{-1}$, respectively, and 50% of the nutrients were removed. In Geongan cheon stream, the TN and TP was 3.0 mg $L^{-1}$ and 0.09 mg $L^{-1}$, respectively, chlorophyll-${\alpha}$ reached a maximum of 239~259 $m^{-3}$, and 50% of the nutrients were removed. In the wastewater treatment outflow, where Scenedesmus sp. already existed, the organism grew well without inoculation. Scenedesmus sp. can grow with proper inoculation and physical turbulence in natural waters, such as lake and stream water, and nutrients can be eliminated as phytoplankton growth occurs.