• Clean Technology
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• v.25 no.4
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• pp.302-310
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• 2019

A constructed wetland with the aerobic tank and anaerobic/anoxic tank connected in series was employed in order to treat highly polluted stream water. The aerobic tank was maintained aerobic with a continuous supply of air through the natural air draft system. Five pilot plants having different residence times were employed together to obtain parameters for the best performances of the wetland. BOD and COD removals at the aerobic tank followed the first order kinetics. COD removal rate constants were slightly lower than BOD. The temperature dependence of COD (θ = 1.0079) and BOD (θ = 1.0083) was almost the same, but the temperature dependence (θ_N) of T-N removal was 1.0189. The SS removal rate was as high as 98% and the removal efficiency showed a tendency to increase with increasing hydraulic loading rate (Q/A). The main mechanism of BOD and COD removal at the anaerobic/anoxic tank was entirely different from that of the aerobic tank. BOD and COD were supplied as the carbon source for biological denitrification. T-P was believed to be removed though the cation exchange between orthophosphate and gravels within the anaerobic and anoxic tanks. The wetland could successfully be operated without being blocked by the filtered solid which subsequently decomposed at an extremely fast rate.

• Ecology and Resilient Infrastructure
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• v.4 no.3
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• pp.142-148
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• 2017

Nitrogen and phosphorus are key factors in causing eutrophication of water body. In this study, ceramics media was selected to increase the removal efficiency of nitrogen and phosphorus. We designed vertical, horizontal flow constructed wetlands to create aerobic and anaerobic flow conditions by using the media, then proceeded to performance evaluations after acrylic reactors were produced. In the case of vertical and horizontal flow constructed wetlands, we measured oxygen concentrations to evaluate aerobic and anaerobic conditions. we got the result of 2.7 mg/L in the aerobic condition, N.D in the anaerobic condition respectively, which suited our purpose. The result of the combined vertical and horizontal flow condition showed that the removal efficiency of SS was 94%, 91%, 61% at 140 min, 80 min, 60 min of running times, respectively, and the removal efficiency of T-P was 84%, 71%, 63% during each running time. In case of T-N, the removal efficiency was 63%, 49%, 42% during each running time. We found that the reactor exerted better removal efficiency when in the short time compared to 12 - 24 hr residence time of existing wetlands. In this study, we conducted experiments to explore functional effects after applying combined vertical and horizontal flow methods in the field. Further study will be carried out to identify its mechanism and administrative perspective.

• Membrane Journal
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• v.19 no.3
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• pp.183-188
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• 2009

After membrane fouling factors in acrylic wastewater were minimized by pretreatment process accompanied with $TiO_2$, it was utilized in MF/UF/RO process. After composing of ultrafiltration/reverse osmosis or microfiltration/reverseosmosiss module set according to types and kinds of membrane, the separation characteristics were examined with the variation temperature and pressure using pretreated acrylic wastewater by membrane module sets. The permeate of ultrafiltration or microfiltration module was sent to reverse osmosis module. It was found that final permeate flux of reverse osmosis module in module set 2 (MWCO 200,000 UF+RO) was excellent. It was shown that the removal efficiency of TDS, T-N and COD was very low and was not dependent on the variation of temperature and pressure in UF and MF modules. From the above result, the removal efficiency of TDS, T-N and COD was very excellent in RO module. The removal efficiency of turbidity in UF and MF module was very high (> 99% removal efficiency). Final water quality of acrylic wastewater treated by the membrane module set was satisfied with effluent allowances limit and membrane module sets were ascertained to reuse wastewater.

• Korean Journal of Environmental Agriculture
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• v.25 no.2
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• pp.129-137
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• 2006

A study was conducted to investigate the behavior of pollutant forms at each area in the sewage treatment plant by natural purification method. The sewage treatment plant by natural purification method that consisted of aerobic and anaerobic area was constructed. The efficiency of sewage treatment depending on the operation time, the loading amount of pollutant season variation were investigated. The removal amount of BOD, COD, TOC and SS in the aerobic area was significantly increased as the treatment proceeded. Decreased BOD, COD, TOC, SS, T-N and T-P depending on the loading amount of pollutants in the aerobic and ananerobic area were mostly insoluble BOD (IBOD), insoluble COD (ICOD), soluble TOC (STOC), volatile SS (VSS), dissolved T-N (DTN) and dissolved T-N (DTP) types, respectively. The removal efficiency of BOD, COD, TOC, SS, T-N and T-P in hot season (summer and autumn) were more than that in cold season (spring and winter). The removal efficiencies of BOD, COD, TOC, SS, T-N and T-P of the effluent were about 92, 89, 73, 95, 46 and 84% in all seasons, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.1
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• pp.37-48
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• 2004

The purpose of this study was to evaluate adaptability of external carbon source using GPS-X program in pilot plant composed with 2-stage denitrification process. The result from analysis of pilot plant operation and GPS-X simulation showed that effluent concentration could be simulated similarly by modifying operation conditions, such as DO concentration, C/N ratio and other calibrated parameter. In order to satisfy the standard of the effluent water quality on T-N of 20mg/L, it required approximately 3.1 of C/N ratio and 50% of nitrogen removal efficiency when influent T-N is 36.9mg/L. To maintain the stable water quality of the receiving water, the effluent T-N concentration should be less than 10-15mg/L and the appropriate C/N ratio to remove nitrogen was 4.27-6.82. The analysis of sensitivity to kinetic coefficient and reaction constant showed that $Y_H$ and ${\mu}_{mAUT}$ were most sensitive to nitrate and ammonia nitrogen, relatively and sensitivity coefficient of their were 1.32, 1.98. It was concluded that as $Y_H$ decreased and ${\mu}_{mAUT}$ increased, the reaction rates of denitrification and nitrification increased and the removal efficiencies of $NO_3{^-}-N$ and $NH_4{^+}-N$ improved.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.3
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• pp.126-133
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• 2004

This study is performed to examine the removal efficiency of organic materials,$NH_4-N$ and P in Swine-Wastewater Treatment using Hybrid-process. It named SBR process, Hybrid-process as RunI(SBR), and Run II(Struvite Tank-SBR), and compared the removal efficiency of each Run. The removal efficiency of the organic materials in each Run is like this; In Run I, TS, VS and COD was 43%, 39%, and 70%, respectively. And in Run II, TS VS, and COD was 52%, 52%, and 82%, respectively. It shows that the removal efficiency of Run II using Strutive Tank is higher. And as for the removal efficiency of $NH_4-N$ and T-P in each Run, Run II using Strutive Tank was 90% and 57%, higher than 56% and 49% of RunI. Especially for $NH_4-N$, Run II showed much higher efficiency, and this proved that Strutive Tank was very efficient process of all for the removal of N and P. As a result of this study, Hybrid-process that combines Strutive Tank and SBR is proved to be a very good process in Swine Wastewater Treatment.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.4
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• pp.63-70
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• 1997

The objectives of this study were to find out the optimum treatment conditions for removing nitrogen in a synthetic wastewater by using microorganisms immobilized with PVA-Freezing method. The samples used as influents to the laboratory scale treatment units were a synthetic wastewater. The experiments in this study were mainly directed to collect the data of nitrogen and organic matter removal efficiencies for the different hydraulic and internal recycle rates conditions, temperature and influent C/N ratios. The removal efficiencies of nitrogen and organic matters were investigated for the operating conditions of HRT 2~12hours, internal recycle rates 50~400%, temperatures $15{\sim}30^{\circ}C$ and C/N ratios 2.5~7.5. The adequate internal recycle rate for removing T-N and $BOD_5$ in the synthetic wastewater was found to be about 300% at the temperature of $30^{\circ}C$ when the ratio of carbon contents to the nitrogen (C/N) in the influent was around 5.5. Under these conditions, the final effluent concentrations of T-N and $BOD_5$ were 8.7 and 8.4 mg/l, respectively.

• Korean Journal of Environmental Agriculture
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• v.30 no.2
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• pp.144-152
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• 2011

BACKGROUND: Eutrophication occurs occasionally in flood control reservoirs around Juam lake in summer and early autumn. Lakeside macrophyte which is one of internal pollutants effects on water quality when it is submerged during water surface is rising after rainy season. METHODS AND RESULTS: To improve water the quality of water from water supply source and to establish the management plan of submerged plants in flood control reservoirs around Juam Lake, the removal and release velocities of nutrients by submerged plants in site 1 and 2 were investigated. Removal or release velocity constant (K) of COD by Carex dimorpholepis Steud in column was 0.07~0.18 $day^{-1}$ at 0~4 days after flooding, -0.23~-0.17 $day^{-1}$ at 5~19 days after flooding and -0.28~0.03 $day^{-1}$ at 20~33 days after flooding. Removal or release velocity constant (K) of T-N by Carex dimorpholepis Steud was 0.02 $day^{-1}$ at 0~4(8) days after flooding, -0.13~-0.10 $day^{-1}$ at 5(9)~33 days after flooding in column. Removal or release velocity constant (K) of T-P by Carex dimorpholepis Steud was 0.05~0.06 $day^{-1}$ at 0~4 days after flooding, -0.14~-0.09 $day^{-1}$ at 5~33 days after flooding. Release velocity constant (K) of nutrients by Miscanthus sacchariflorus Benth was lower than that by Carex dimorpholepis Steud. In site 1, the amount of nutrients release by Carex dimorpholepis Steud was 6,719 kg/month/area for COD, 2,397 kg/month/area for T-N and 466 kg/month/area for T-P. The amounts of nutrients release by Carex dimorpholepis Steud were higher than those by Miscanthus sacchariflorus Benth in both sites. CONCLUSION(s): The results of this study suggest that COD, T-N and T-P in water quality of Juam lake were strongly influenced by submerged plants in flood control reservoirs.

• Korean Journal of Environmental Agriculture
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• v.28 no.2
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• pp.97-105
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• 2009

A constructed wetland which was composed of aerobic and anaerobic areas was evaluated for 3 years to effectively treat the sewage produced in farming and fishing communities. For 3 years in a constructed wetland, biochemical oxygen demand(BOD), chemical oxygen demand(COD), suspended solids(SS), total nitrogen(T-N), and total phosphorus(T-P) in effluent were 0.2${\sim}$11.8, 1.0${\sim}$41.9, 1.1${\sim}$6.5, 4${\sim}$60 and 0.02${\sim}$3.51 mg/L, respectively. Removal rate of BOD, COD and SS in effluent were 97, 92 and 99%, respectively, in the third year. As time goes by, removal rate of T-N and T-P in treated water in aerobic area and effluent were gradually increased in a constructed wetland. In the third year, removal rate in effluent were 62 and 73%, respectively. By the seasons, removal rate of BOD, COD, SS, T-N and T-P were 97${\sim}$98, 87${\sim}$91, 99, 43${\sim}$61 and 76${\sim}$86%, respectively. Removal rate of BOD, COD, SS and T-P were not affected by the seasons, but that of T-N in winter and spring were decreased than the other seasons.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.499-506
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• 2005

This study was performed to investigate the effects of influent C/N ratio on the removal of organic and nitrogenous compounds by two nonwoven fabric filter bioreactors. The reactors were alternately aerated at an aeration/nonaeration period ratio of 60 min/60 min, and fed with wastewater only during nonaeration period. The influent C/N ratio (COD/TKN) was gradually reduced from 10 to 2. The influent was prepared by diluting the leachate from a foodwaste treatment facility in I city so that the COD concentration could be about 2,500 mg/L. The C/N ratio of the wastewater was adjusted by adding ammonium chloride. The results of the experiment showed that the COD and BOD concentration of the effluent was $40{\sim}54\;mg/L$ and $1{\sim}4\;mg/L$, respectively at the C/N ratios of $10{\sim}3$, and the effluent SS concentration was always below 2.0 mg/L. The T-N removal efficiencies were 96% or higher at C/N ratios of $10{\sim}5$, but decreased to 83% and 81%, respectively at the C/N ratios of 3 and 2.8. At the C/N ratios of 2.6 and 2, the effluent quality deteriorated due to ammonia toxicity. The fraction of nitrifying microorganism in the reactors increased from 10% to 20% as the C/N ratio decreased from 5 to 2.6. Alkalinity consumed were $3.12{\sim}3.49\;g$ alkalinity/g T-N removed at the C/N ratios of $10{\sim}5$, which are lower than the theoretical value of 3.57. However, the ratio increased to 4.63 and 4.87 g alkalinity/g T-N removed, respectively at the C/N ratios of 3 and 2.8.