• 한국물환경학회지
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• 제20권2호
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• pp.104-109
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• 2004

Removal of nutrients from domestic sewage or industrial wastewater is needed to protect surface waters from eutrophication. This research was carried out to remove the nitrogen (N) and phosphorus (P) from the wastewater using the iron oxide obtained from the steel industry and the natural zeolite, respectively. This research was conducted in both batch and continuous systems. The removal efficiency of the nutrients was evaluated in the batch system using the varying concentrations of zeolite and iron oxide added. The removal efficiency of N was 60% at the 8g of zeolite added. In the same condition, the removal efficiencies of N were 76% and 82% at 12g and 16g of zeolite added, respectively. Removal efficiency of P was 80% as 8g of iron oxide was added. The removal efficiency of P was correspondingly increased as the concentration of iron oxide was increased. Continuous column system was also used to evaluate the removal efficiency of N and P by the addition of zeolite and ferric oxide, respectively. Removal efficiencies of N were compared in the mixed packing, two stage, and four stage columns, respectively. The removal efficiencies (80%) of N in the separate packed columns (two and four stages) were higher than the mixed packing column (400%) after 90 hr. Whereas, the removal efficiencies of P were similar to each other in the three columns.

• 한국응용과학기술학회지
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• 제23권2호
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• pp.130-136
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• 2006

Theoretical total nitrogen removal efficiency and reactor volume ratio in oxic-anoxic-oxic system can be found by influent water quality in this study. The influent water quality items for calculation were ammonia, nitrite, nitrate, alkalinity, and COD which can affect nitrification and denitrification reaction. Total nitrogen removal efficiency depends on influent allocation ratio. The total nitrogen removal follows the equation of 1/(1+b). Optimal reactor volume ratio for maximum TN removal efficiency was expressed by those influent water quality and nitrification/denitrification rate constants. It was possible to expect optimal reactor volume ratio by the calculation with the standard deviation of ${\pm}14.2$.

• 상하수도학회지
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• 제27권3호
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• pp.383-394
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• 2013

A sedimentation basin is used to remove suspended sediments which can cause abrasive and erosive wear on hydraulic turbines of hydropower plants. This sediment erosion not only decreases efficiency of the turbine but also increases maintenance costs. In this study, the three-dimensional numerical simulations were carried out on the overseas hydropower project. The simulations of flow and suspended sediment concentration were obtained using FLOW-3D computational fluid dynamics code. The simulations provide removal efficiency of a sedimentation basin based on particle sizes. The influence of baffles on the flow field and the removal efficiency of suspended sediments in the sedimentation basin has been investigated. This paper also provides the numerical simulations for sediment-induced density currents that may occur in the sedimentation basin. The simulation results indicate that the formation of density currents decreases the removal efficiency. When a baffle is installed in the sedimentation basin, the baffle provides intensive settling zones resulting in increasing the sediments settling. Thus the enhanced removal efficiency can be achieved by installing the baffle inside the sedimentation basin.

• 분석과학
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• 제29권3호
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• pp.126-135
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• 2016

상수원으로 유출될 가능성이 높은 잔류의약물질 대상으로 정수처리공정의 단위 공정별 잔류의 약물질 제어 효율을 평가하였다. 응집 공정에서는 Sulfonamide계 항생제는 22.6~42.1 % 제거 되었으며, Naproxen 28.2 %, Acetaminophen 20 %가 제거되었다. Trimethoprim은 4.4 %, Erythromycin은 2.4 %로 낮은 제거율을 보여 주었으며, Aspirin은 전혀 제거되지 않았다. 염소처리와 응집 혼합 공정을 적용하였을 때, 염소 주입량이 증가할수록 제거율이 증가되었다. 염소주입농도 3 mg/L일 때 Sulfonamide계 항생제, Acetaminophen, Naproxen은 100 %, Trimethoprim은약 98%로높은제거효율을나타내었으며 Erythromycin은 약 55 %, Aspirin은 약 10 %로 낮은 제거율을 보여 주었다. 분말활성탄 흡착 공정을 적용하였을 때, 분말활성탄 주입 농도가 증가할수록 제거율이 증가되었다. Sulfonamide계 항생제의 경우 1 mg/L에서 약 18~50 % 제거율을 보였으며, 25 mg/L에서는 약 80 % 이상으로 제거율이 증가하였다. 정수처리 공정에서 잔류의약물질의 효율적인 처리를 위한 염소처리와 흡착, 응집 공정의 적정 주입농도를 평가한 결과 염소 3 mg/L, 분말활성탄 10 mg/L, 응집제 15 mg/L을 적용했을 때 약 90 % 이상이 제거되었다.

• 한국환경보건학회지
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• 제23권1호
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• pp.50-54
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• 1997

The removal efficiency of nutrient was investicated by using Glycine max Meer seedling. After budding, Glycine max Merr was raised at darkness for 4 days. During cultivation, the removal efficiency of $NO_2-N+NO_3-N$ was up to 90% with initial concentration of 20-100 ppm. The removal efficiency of PO$_4$-P was up to 80% with initial concentration at 30 ppm, but it was down to 22% and 27% at 40 ppm and 50 ppm. When the removal efficiency of nutrient was compared with alternating 12 hours' light and darkness, the removal efficiency of NO$_2$-N + NO$_3$-N was up to 90% at below 60 ppm. It was not different from each other. But it was particularly low about 62% and 34% at 80 ppm and 100 ppm in alternating 12 hours' light. The removal efficiency of PO$_4$-P was low at alternating 12 hours' light between 10-50 ppm on the whole range. The neutralizing capacity of pH was shown in acidity and alkalinity except strong acidity(below pH 3). The initial pH was neutralized at 6.0-7.7 of pH after 4 days. Particularly, Glycine max Meer seedling that was difference from other water plants, was shown the neutralizing capacity in strong alkalinity.

• 한국물환경학회지
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• 제31권4호
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• pp.351-359
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• 2015

The study on the improvement of discharge water quality from domestic wastewater treatment plant (DWTP) was performed in a filter type bioelectrochemical system. The COD removal efficiency for a synthetic discharge water was about 88%, and the effluent COD was less than 5mg/L. The nitrification efficiency of the bioelectrochemical system was over 97%, but a considerable amount of the nitrogen was remained as nitrate form in the effluent. The total nitrogen removal efficiency was only around 30%. There are no significant differences in the removal of COD and nitrogen at 0.6 and 0.8V of the applied voltages between anode and cathode. The removal of COD and nitrogen in the system were quite stable when the HRT ranged from 60 to 15 minutes, and at 10 minutes of HRT, the nitrification efficiency was slightly decreased. The performance of the bioelectrochemical system has quickly recovered from the shocks in the influent due to high concentration of COD and nitrogen. For the effluent that discharged from the DWTP, the removal efficiencies of COD and total nitrogen from the bioelectrochemical system were 50 and 30%, respectively. Thus the bioelectrochemical system was a feasible process for further polishing the effluent quality from DWTP.

• 한국환경과학회지
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• 제8권6호
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• pp.699-704
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• 1999

The Photodegradation efficient of total organic compounds in the drinking water has been studied using the methods of photocatalytic reaction and laser beam irradation. The results are summarized as follows; 1. The photodegradation efficiency of total organic compounds shows as $50\%\;to\;80\%$ as within one hour and after this the efficiency is decreased slowly. 2. The photodegradation efficiency of total organic compounds shows as 65 to $90\%$ within 3.3min. when Nd : YAG beam is irradiated to the water layer. 3. An excellent observation of the organic compound removal efficiency gives revealed in that case of the longest wavelength of 532nm is irradiated among the three kinds of laser beam sources of 532nm, 355nm and 266nm. 4. The organic compound removal efficiency shows high in the case of UV beam irradiation in the thin layer of water. However the efficiency is not depended on the thickness of water layer severely. 5. The removal efficiency of the organic compounds in the direct irradiation shows higher than the indirect irradiation in the case of UV beam, but the efficiency is not depended on the direction of irradiation in the case of Nd : YAG beam irradiation.

• 상하수도학회지
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• 제13권4호
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• pp.27-34
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• 1999

An experimental study on improvement of the paper-mill wastewater treatment using the pure oxygen activated sludge process was conducted. The effects of hydraulic retention time(HRT) and BOD loading on organic removal efficiency were investigated. The BOD removal efficiencies were above 90% under all examined HRTs except for HRT of 3 hours. The increase of HRT from 3 hours to 6 hours, and to 12 hours significantly improved BOD and COD removal efficiencies, respectively. However, additional increase of HRT did not affect organic removal efficiency. F/M ratio change at fixed HRT did not affect organic removal efficiency. However, F/M ratio investigated in this study(0.11~1.98kgBOD/kgMLVSS/day) was 5 times greater in maximum than that of conventional activated sludge process, which implies that pure oxygen activated sludge process can treat wastewater with high organic strength. Under the same HRT, the volumetric BOD loading change cause no effect on organic removal efficiency also.

• 한국물환경학회지
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• 제37권4호
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• pp.286-295
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• 2021

The removal efficiency of road-deposited sediment (SDR) by road sweeping was analyzed by performing particle size analysis before and after road sweeping at four highways during May to December 2019. The SDR accounted for the largest proportion in the range of 250 to 850 ㎛ and the degree of its proportion had an effect on the particle size distribution curve. The particle size distribution of the collected sediments showed a similar distribution at all sites. Below 75 ㎛, the removal efficiency of SDR showed a constant value around 40%, but above 75 ㎛, it increased as the particle size increased. The removal efficiency was 82-90% (average 86%) for gravel, 66-93% (average 79%) for coarse sand, 35-92% (average 64%) for fine sand, 29-69% (average 44%) for very fine sand, 19-58% (average 40%) for silt loading, 10-59% (average 40%) for TSP, 13-57% (average 40%) for PM10, and 15-61% (average 38%) for PM2.5. SDR removal efficiency showed an average of 69% for the four highways. It was found that if the amount of SDR was less than 100 g/m², it was affected by the road surface condition and had a large regional deviation. As such, the amount of SDR and the removal efficiency increased. The fine particles, which have relatively low removal efficiency, contained a large amount of pollutants, which is an important factor in water and air pollution. Therefore, various measures to improve the removal efficiency of fine particles in SDR by road sweeping are needed.

• 한국환경복원기술학회지
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• 제8권1호
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• pp.37-44
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• 2005

Nitrate($NO_3-N$) and total nitrogen(TN) removal by a reed wetland with open water(Wetland 1) was compared with that of a reed wetland without open water(Wetland 2) from March to October 2002. The two wetlands were 25mL by 6mW. An open water area, 3mL by 6mW was designed at the middle of Wetland 1. Reeds(Phragmites australis) were transplanted into the wetlands in June 2000. Water of Sinyang Stream flowing into the Kohung Estuarine Lake located in the southern part of Korea was pumped into a primary treatment pond, whose effluent was discharged into the secondary pond. Effluent from the secondary pond was funneled into the wetlands. Inflow into the wetlands averaged about 20.0$m^3$/day and their hydraulic retention time was approximately 1.5 days. Average $NO_3-N$ removal by Wetland 1 was 117.61mg/$m^2{\cdot}day$ and that by Wetland 2 was 106.39mg/$m^2{\cdot}day$. $NO_3-N$ removal efficiency of Wetland 1 and 2 was 37% and 34%, respectively. TN removal by Wetlands 1 and 2 averaged 226.80 and 214.54mg/$m^2{\cdot}day$, respectively. TN abatement efficiency of Wetland 1 was 43% and that of Wetland 2 was 40%. $NO_3-N$ removal efficiency of Wetland 1 was significantly higher(p=0.038) than Wetland 2. TN removal efficiency of Wetland 1 was also significantly higher(p=0.044) than Wetland 2. The wetland with open water was more efficient for removal of $NO_3-N$ and TN than one without.