• Journal of Korean Society of Environmental Engineers
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• v.30 no.1
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• pp.45-53
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• 2008

In this paper, the property of influent water and variations of removal efficiencies in each unit processes were studied based on the experiment data from the advanced water treatment plant in a city of Korea. The microbial species in the biological activated carbon(BAC) after backwashing of activated carbon filtration tank(ACFT) were also identified. The property and the removal efficiencies were evaluated by considering 8-9 items. The variations of 4 items were investigated from the influent and effluent of ACFT. SEM recording were conducted on BAC samples before and after backwashing. And the existence of attached microorganisms were identified through HPC(Heterotrophic Plate Counter) investigation. For the property of influent water, the concentrations of most items were maintained in the constant ranges, some items had seasonal properties. For the removal efficiencies, there were some items showing similar monthly-pattern and increasing with time, other items decreasing at the ozone contactor. Through these investigations, it was possible to distinguish the target items, which were removed by the advanced processes. The existence of microorganisms in ACFT could be predicted based on the variation curve of NH$_3$-N, and this fact were proved by SEM and HPC.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.2179-2183
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• 2008

지금까지 분포형 모형 개발에 대한 많은 노력이 있음에도 불구하고 여러 제약사항들에 의해 잠재력을 보여주는 정도로 활용되어 왔으나, 최근 급속도로 발전하는 컴퓨터의 계산능력, DEM 등 디지털정보의 구축이 진행되어 오고 있고, GIS 및 인공위성 영상기법의 발달로 공간적인 비균질성을 고려하여 유출과정에서 운동역학적인 이론을 기반으로 물의 흐름을 수리학적으로 추적해 나가는 물리적기반의 분포형 유출모형의 활용도가 높아지고 있다. 본 모형개발에 있어 이론적 배경이 된 모형은 1998년부터 일본 교토대학 방재연구소 코지리 연구실에서 개발 중인 Hydro-BEAM으로 유역 물순환의 건전성을 평가하기 위하여 장기간의 유역 내 유량, 수질을 시계열 및 공간적으로 파악하여 유역의 영향평가를 위해 개발된 물리적 기반의 격자구조를 가진 분포형 장기유출 모형이다. 유출량 계산은 유역내 수평 유출량산정 모듈로서 평면 분포형의 격자형을, 연직 분포형으로는 $A{\sim}B$층의 수평유출량은 하천으로 유입하고, C층은 하천유량에 영향을 미치지 않는 지하수층으로 가정하는 다층모형을 이용해서 A층, 지표 및 하도흐름은 운동파 법(kinematic wave)으로, $B{\sim}C$층의 유출량은 선형저류법으로 계산하는 모형이다. 본 연구에서는 격자흐름방향을 4방향에서 8방향으로 개선하였고, 모형의 각종 수문매개변수들을 GIS와 연계하여 직접 입력할 수 있도록 하였으며, 물리적기반의 침투과정을 모의할 수 있도록 Green & Ampt모듈을 추가하고, 향후 레이더 강우 및 수치예보강우의 홍수유출예측을 염두에 두고 격자강우량을 활용할 수 있도록 하는 등 홍수유출해석을 위한 분포형 강우-유출모형으로 개선 하였고, 이를 남강댐유역에 적용해 봄으로써 모형의 적용성을 검토해 보고자 하였다. 홍수기동안의 지표흐름과 지표하 흐름의 시간적 변화와 공간적 분포를 모의할 수 있었으며, 전처리과정으로서 ArcGIS 혹은 ArcView등의 GIS 프로그램을 이용하여 모형에 필요한 ASCII형태의 입력 매개 변수 자료들을 가공하였다. 또한 후처리과정으로서 모형의 수행결과인 유역내의 유출량 분포 등을 GIS상에서 나타낼 수 있도록 ASCII형태로 출력하도록 구성하였다. 남강댐유역을 대상으로 유역을 500m의 정방형 격자로 분할하고 수계망을 통하여 유역 출구까지 운동파이론에 의해 추적 계산하였으며, 수문곡선 비교결과 재현성 높은 결과를 보여주었다. 모형의 정확성 및 실용성에 대한 보다 정확한 평가를 위해서는 향후 다양한 강우 사상 혹은 다양한 크기의 유역에 대한 유출량의 재현성 및 매개변수 등에 검증이 이루어져야 할 것이다.

• Journal of Environmental Science International
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• v.18 no.9
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• pp.971-981
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• 2009

An objective of this study is as follows: 1) performing sensitivity analysis and parameter estimation of RMA2 and RMA4 models for the West-Nakdong River, 2) drawing up alternatives of gates-operation for water-quality enhancement, and 3) quantitative evaluation of methodology of 'flow-restoration by gates-operation' among 'Comprehensive Plan Improving Water-Quality in the West-Nakdong River(WNR)' with the target water-quality(BOD at Nakbon-N point: below 4.3 mg/L). The parameters for the RMA2 (depth-averaged two-dimensional flow model) and RMA4 (depth-averaged two-dimensional water-quality model) were determined by sensitivity analysis. Result of parameter estimation for RMA2 and RMA4 models is $1,000\;Pa{\cdot}s$ of the eddy viscosity, 20 of the Peclet number, 0.025 of the Manning coefficient, and $1.0\;m^2/s$ of the diffusion coefficient. We have evaluated the effects of water-quality enhancement of the selected alternatives by numerical simulation technique with the models under the steady-state flow condition and the time-variant transport condition. Because of no-resuspension from river bottom and considering BOD as conservative matter, these simulation results slightly differ from real phenomena. In the case of $50\;m^3/s$ of Daejeo-gate inflow, two-dimensional flow pn results result represents that small velocity occurs in the Pyungkang Stream and no flow in the Maekdo River. In the WNR, there occurs the most rapid flow near timhae-bridge. In the WNR, changes of water-quality for the four selected simulation cases(6, 10, 30, $50\;m^3/s$ of the Daejeo-gate inflow) were predicted. Since the Daejeo-Gate and the Noksan-Gate can be opened up to 7 days, it would be found that sustainable inflow of $30\;m^3/s$ at the Daejeo-gate makes BOD in the WNR to be under the target of water-quality.

• Journal of the Korean GEO-environmental Society
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• v.10 no.2
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• pp.37-43
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• 2009

With the economic development of Korea, sewage treatment facilities and waste food treatment facilities have been steadily increased. These facilities have positive effects such as the conservation of the water resources quality and waste food recycling while they also affect the neighborhood life with severe odor problems. Therefore, it was first collected sludge samples from 5 sewage treatment facilities and 5 waste food treatment facilities where the amounts of waste produced from above sites are relatively immense in Busan and estimate the $H_2S$ emission rates. Then it was selected 1 sample which has the highest emission rate of $H_2S$. Using flux chamber and GC/FPD analyses, it was tried to quantify the emitted amount of sulfonic gas concentration under anoxic condition. The sludge sample obtained from Noksan sewage treatment facility has the highest emission rate of $H_2S$. This sample contained 156.18 mg/kg $H_2S$. The odor compounds were analyzed using GC/FPD and the concentrations were converted to odor quotient. Among odor compounds the ratio of $CH_3SH$ (methylmercaptan) for the total odor quotient was 47.3% and considered to be the main odor compound in the sample.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.301-310
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• 2008

This study was to analyze characteristics of fish compositions and longitudinal distribution, based on trophic and tolerance guild at 22 sampling sites of Yeongsan River watershed during 2003$\sim$2006, and also to compare before and after the estuary dam construction. The collected fishes, based on catch per unit effort (CPUE), were 44 species in the watershed and dominant fishes were Zacco platypus, Acheilognathus macropeterus, Zacco temminckii and Carassius auratus. According to comparative analysis of fish in the non polluted sites (NPS) vs. polluted sites (PS), the number of species and individuals was lower by 70% in the PS than the NPS, indicating ecological degradations by chemical pollutions or/and habitat modifications. The relative abundance of sensitive and insectivore species decreased as the stream order increases, while tolerant and omnivore species increased with the stream order. In this survey, largemouth bass (Micropterus salmoides), which is a top-carnivore and exotic species, may influence trophic guild system throughout active predations on endemic species, resulting in modifications of ecological functions. The construction of estuary dam on Yeongsan River in 1981 resulted in wider lacustrine zone and desalinated through limitation of seawater input. These physical changes have caused increases of lentic dwelling species and limited fish migrations (i.e., eel). Overall, fish fauna and composition analyses showed that the number of species and individuals in this water body may be reduced due to inputs of pollutants from the watershed, habitat modifications, and increases of exotic species (largemouth bass). For these reasons, effective lake management strategies are required for the ecosystem conservation.

• Korean Journal of Environmental Biology
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• v.34 no.2
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• pp.116-123
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• 2016

The ecotoxicity tests for metal plating wastewater were conducted using Daphnia magna (D. magna) and Euglena agilis (E. agilis). Evaluation for sources of toxicity was performed by 1) Correlation analysis between the concentration of individual metals in the metal plating wastewater and the toxic effects on D. magna, 2) Toxicant identification evaluation methods including graduated pH method, EDTA procedure and sodium thiosulfate procedure, 3) Comparison of toxic effect value ($EC_{50}$ or $LC_{50}$) of individual metal on D. magna and it's concentration in the metal plating wastewater. To evaluate the possibility of E. agilis, a Korean domestic organism, as a test model organism for metal plating waste water, E. agilis toxicity test was also assessed using on-line euglena ecotoxicity system (E-Tox system). Based on toxicant characterization test using D. magna, it was expected that SS, oxidants and heavy metals are responsible for toxicity of metal plating waste water. Especially Cu, Hg, and Ag were the major cationic metals that caused toxicity. E. agilis is less sensitive than D. magna based on the $EC_{50}$ value however it shows prompt response to toxic test substances. E. agilis shows even a significant effect on the cell swimming velocity within 2 min to toxic metal plating wastewater. Our study demonstrates that E. agilis test can be a putative ecotoxicity test for assessing the quality of metal plating waste water.

• The Journal of Engineering Geology
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• v.26 no.3
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• pp.371-382
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• 2016

Saltwater intrusion in coastal regions can be detected by using numerous geochemical constituents in groundwater. However, insufficient numbers of groundwater data can often make us difficult to interpret saltwater intrusion. Probability statistics technique enables statistical prediction using a limited numbers of water quality data for a wider range and can make to effectively evaluate saltwater intrusion through a characterized distribution of probability. This study evaluated saltwater intrusion by applying probability statistics to the chemical constituents in groundwater, coastal discharge, and stream water in the coastal areas of Busan City. By the result of the study, it is proven that Na⁺, Mg²⁺, K⁺, SO₄²⁻, and Cl⁻, abundantly contained in seawater, are valuable indicators for evaluating saltwater intrusion. On the other hand, it is judged that Si⁴⁺, Fe²⁺, NO₃⁻, and PO₄³⁻, showing similar probability distribution in groundwater, coastal discharge, and stream water, are not appropriate indicators for the detection of saltwater intrusion.

• Journal of Navigation and Port Research
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• v.26 no.1
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• pp.137-145
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• 2002

Water flow simulations for environmental problems often require local detailed analyses for better understanding and accurate prediction of the fate of pollutant in water bodies. This study deals with the development and application of a two-dimensional flow an dispersion model to the coastal water area to find out possible changes due to the wide port development plan. As far as the spatial discretization is concerned, the finite element method is attractive because of its flexibility and ability to naturally treat complex coastal geometries. The model uses finite element theory and the Galerkin weighted-residual approach as its basis. Developed model is applied to the Busan New harbor Construction site. Results from the model were compared with the measured water level and flows in four stations. The flow pattern by the model shows to be similar to the observed data away from the construction site where the flow is not affected. From the simulation results, it is concluded that the model may be useful for numerous other studies for planning and management purposes, especially flow and pollution dispersion in the coastal water bodies where the flow is so complicated.

• Journal of Wetlands Research
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• v.19 no.1
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• pp.90-102
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• 2017

In this study, various types of nutrient models were tested by using two tears's water quality data collected from the stormwater wetland in Korea. Based on results, most important factor influencing nitrogen removal was hydraulic loading rate, which indicates that surface area of wetland is more important than its volumetric capacity, and model proposed by WEF was found to give a least error between measured and calculated values. For the phosphorus, in case assuming a power relationship between rate constant and temperature, the best prediction result were obtained, but temperature was most sensitive parameter affecting phosphorus removal. In addition, denitrification was always a limiting step for the nitrogen removal in this particular wetland mostly due to the lack of carbon source and high dissolved oxygen concentration. In this paper, several alternatives to improve nitrogen removal, including proper arrangement and designation of wetland elements and use of floating plants or synthetic fiber mat to control oxygen level and to capture the algal particles were proposed and discussed.

• Journal of Korea Water Resources Association
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• v.43 no.2
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• pp.131-138
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• 2010

Due to the increased water demand and severe drought as an effect of the global warming, the effluent from wastewater treatment plants becomes considered as an alternative water source to supply agricultural, industrial, and public (gardening) water demand. The effluent from the wastewater treatment plant is a sustainable water source because of its good quality and stable amount of water discharge. In this study, the water reuse system was developed to minimize total construction cost to cope with the uncertain water demand in future using two-stage stochastic linear programming with binary variables. The pipes in the water reuse network were constructed in two stages of which in the first stage, the water demands of users are assumed to be known, while the water demands in the second stage have uncertainty in the predicted value. However, the water reuse system has to be designed now when the future water demands are not known precisely. Therefore, the construction of a pipe parallel with the existing one was allowed to meet the increased water demands in the second stage. As a result, the trade-off of construction costs between a pipe with large diameter and two pipes having small diameters was evaluated and the optimal solution was found. Three scenarios for the future water demand were selected and a hypothetical water reuse network considering the uncertainties was optimized. The results provide the information about the economies of scale in the water reuse network and the long range water supply plan.