프러티바반다리 Pratibha Bhandari , 김동수 Dong S Kim

DOI: Vol.27(No.1) 1-8, 2011

Although Nepal is naturally bestowed with ample water resources, not all of the population has access to safe and clean drinking water. Waste water treatment is almost nonexistent. In the recent days the flow of population in the urban areas has increased the existing challenges of providing safe water and promoting sanitation. The prevalence of water borne diseases is high. This paper presents overview of issues like water pollution, arsenic contamination of drinking water, waste water treatment and effects of water contamination on public health. Comparison between waste water treatment regulations in South Korea and Nepal has also been made. Implementation strategies to tackle the existing water related problem for promoting public health is also recommended.

Arsenic contamination, Nepal, Public health, Safe water, Water pollution, Waste water

최대규 Daeg Yu Choi , 김진관 Jin Kwan Kim , 이재관 Jae Kwan Lee , 김상단 Sang Dan Kim

DOI: Vol.27(No.1) 9-18, 2011

In this study the optimal volume for non-point source control retention is estimated considering spatio-temporal variation of land surface. The 3-parameter mixed exponential probability density function is used to represent the statistical properties of rainfall events, and NRCS-CN method is applied as rainfall-runoff transformation. The catchment drainage area is divided into individual 30 m×30 m cells, and runoff curve number is estimated at each cell. Using the derived probability density function theory, the stormwater probability density function at each cell is derived from the rainfall probability density function and NRCS-CN rainfall-runoff transformation. Considering the antecedent soil moisture condition at each cell and the spatial variation of CN value at the whole catchment drainage area, the ensemble stormwater capture curve is established to estimate the optimal volume for an non-point source control retention. The comparison between spatio-temporally varied land surface and constant land surface is presented as a case study for a urban drainage area.

Non-point source management, NRCS-CN, Stormwater capture curve, Urban hydrology

유승훈 Seung Hoon Yu , 이범연 Bum Yeon Lee , 이강현 Kang Hyun Lee , 박신정 Shin Jung Park , 이창희 Chang Hee Lee

DOI: Vol.27(No.1) 19-29, 2011

In order to assess the influences of bottom sediment on water quality, following measurement were made. (1) Estimations of pollutant loads from the bottom sediment based on mass balance concept, (2) measurements of pollutant concentrations in the sediment to assess the pollution level and influence potential, (3) in situ and laboratory measurements of Sediment Oxygen Demants (SOD) and pollutant load (sediment release) from bottom sediment. Analyses of inflow and outflow loadings using simple mass balance show that there are some variations found according to the pollutants. However, there is no consistent evidence that the sediment can be a source of pollutants. Pollutant concentrations in the sediment range 16~724.8 mg/kg (COD), 1.68~12.64 mg/kg (T-P), 5.6~76.8 mg/kg (T-N), 0.32~21.6 mg/kg (NH3-N), 0.092~0.544 mg/kg (NO2-N), 4.8~18.4 mg/kg (NO3-N), and 1.59~11.23 mg/kg (PO4-P). Measured SOD ranges 0.190~0.802 g·m-2·d-1 and measured release rate ranges -1618.42~10 mg/m2·d(COD), -12~16 mg/m2·d(T-P), -197.37~140 mg/m2·d(T-N), 0.4~74.32 mg/m2·d(NH3-N), -2.04~0.8 mg/m2·d (NO2-N), -70~40 mg/m2·d (NO3-N), and -26.11~28.55 mg/m2·d(PO4-P). All study results indicate that bottom sediments in the Seoha weir show only limited effects on the water quality. It implies that sediment dredging is not an effective option or management measure to reduce pollutant loading.

Kyongan stream, Sediment dredge, Sediment oxygen demand, Stream weir, Total pollutant Load management system

연인성 In Sung Yeon , 조용진 Yong Jin Cho

DOI: Vol.27(No.1) 30-35, 2011

2D pollutant transport model was applied to the simulation of contaminant transport in the channel. At first, two kinds of virtual channels having different slopes were designed. The distribution of contaminant, which flows from one of the three drainages to the main channel, was simulated by each 2D model. Concentrations of 745 nodes were converted to input data of neural network model (Multi-perceptron) for training and verification using matrix. The first three cases (Case A-1, A-2, A-3) were used for training Multi-perceptron, the other three cases (Case B-1, B-2, B-3) were used for verification. As a result, Multi-perceptron reasonably divided the cases into the three characteristics which have different contaminant distributions due to the different input point of water pollution source. It can be a useful methodology for the water quality monitoring and backtracking.

Backtracking, 2D model, Multi-perceptron, Water pollution source

임봉수 Bong Su Lim , 김도영 Do Young Kim , 이광춘 Kuang Chun Lee

DOI: Vol.27(No.1) 36-43, 2011

This study is selected two points of combined sewer that occurred Fish Kill after first flush, that analyzed generation of pollutants and stream runoff generation of combined sewer overflows (CSOs) as fine weather and rainfall. In addition, this study was to analyze the relationship between CSOs and sediments, to propose measures to reduce the sediment relevant with CSOs and rainfall runoff from entering sewage treatment plants and measures for discharged directly into streams when indicate relatively good water quality after overflow. Sediments in combined sewer system was discharged about 50~80% as overflows during rainfall and we can reduce the amount of the CSOs at least 50% or more if the sewer does not exist in the sediments because of the amount of discharge about the amount of intercept has been investigated by 3~5 times. Because of velocity at sediment interval in sewer is very low, sewage velocity of about 3~5 times as much as it can increase the amount of sediment can be reduced if the separation wall is installed. Effective control of BOD overflow load is respectively 77.5%, 75.8% at first point, second point by the separation wall is installed. Drainage area greater than area in this study or many combined sewer overflows region is increased the more effective control of separation wall. Turbidity to measure changes in water quality of overflows can be used as an factor to control the intercept flows because the intercept flows(3Q) after the first flush has lowered removal efficiency and increases the operational load of sewage treatment plants. Sewage water quality after a overflow when the reasonable turbidity was measured at this point flows to excluded intercept flow(1Q) can be discharged to stream.

Control of CSOs, Reasonable turbidity, Sediments, Separation wall, Velocity of sewage

이상민 Sang Min Lee , 김미형 Mi Hyung Kim

DOI: Vol.27(No.1) 44-53, 2011

Membrane bio-reactor (MBR) has several advantages over the conventional activated sludge process, including a high biomass, low sludge production, and better permeate quality. Therefore, the MBR have gained popularity for municipal and industrial wastewater treatment. However the MBR usually were used for sewage and low strength wastewater treatment because of membrane fouling problem and limitation of oxygen transfer into biomass. In this study, the hybrid process combining MBR and pure oxygen was tested for high strength organic wastewater treatment in the COD loading range from 2 to 10 kgCOD/m3·day. The hybrid process, membrane coupled pure oxygen high compact reactor (MPHCR), had been operated for one year and operation parameters, the effect of COD loading, MLSS concentration and the location of membrane module were studied for membrane fouling characteristic. Also membrane resistance test and the component of foulant was analyzed to investigate what is specific foulant in the MBR.

Exo-cellular polymer, ECP, Filtration characteristic, Fouling, Membrane Bio-reactor, MBR, Sludge particle, Sludge viscosity

정효상 Hyo Sang Jung , 이강춘 Gang Choon Lee

DOI: Vol.27(No.1) 54-60, 2011

To evaluate the feasibility of electrodialysis for copper removal from industrial wastewater, the effect of operating parameters on the removal of copper was experimentally estimated. The limiting current density (LCD) linearly increased with the copper concentration and the flow rate. The time when the copper concentration of diluate reaches to 3 mg/L was linearly proportional to initial concentration of diluate, and the concentration of concentrate did not affect the removal rate. Increase in the flow rate gave a positive effect on the removal rate and became insignificant at flow rates greater than 2.4 L/min. The removal rate increased with the applied voltage. From the operation of the electrodialysis module used in this research, the flow rate of 2.4 L/min and the voltage corresponding to the 80~90% of LCD were found be the optimum operating condition for the copper removal from highly concentrated copper solutions.

Copper Removal, Electrodialysis, Heavy metal, Limiting current density, Wastewater treatment

장원석 Won Seok Jang , 문종필 Jong Pil Moon , 김남원 Nam Won Kim , 유동선 Dong Sun Yoo , 금동혁 Dong Hyuk Kum , 김의재 Ik Jae Kim , 문유리 Yuri Mun , 임경재 Kyoung Jae Lim

DOI: Vol.27(No.1) 61-72, 2011

In order to assess hydrologic and nonpoint source pollutant behaviors in a watershed with Soil and Water Assessment Tool (SWAT) model, the accuracy evaluation of SWAT model should be conducted prior to the application of it to a watershed. When calibrating and validating hydrological components of SWAT model, the Nash-Sutcliffe efficiency coefficient (EI) has been widely used. However, the EI value has been known as it is affected sensitively by big numbers among the range of numbers. In this study, a Web-based flow clustering EI estimation system using K-means clustering algorithm was developed and used for SWAT hydrology evaluation. Even though the EI of total streamflow was high, the EI values of hydrologic components (i.e., direct runoff and baseflow) were not high. Also when the EI values of flow group I and II (i.e., low and high value group) clustered from direct runoff and baseflow were computed, respectively, the EI values of them were much lower with negative EI values for some flow group comparison. The SWAT auto-calibration tool estimated values also showed negative EI values for most flow group I and II of direct runoff and baseflow although EI value of total streamflow was high. The result obtained in this study indicates that the SWAT hydrology component should be calibrated until all four positive EI values for each flow group of direct runoff and baseflow are obtained for better accuracy both in direct runoff and baseflow.

K-means clustering EI estimation system, Nash-Sutcliffe efficiency coefficient, Soil and Water Assessment Tool, SWAT auto-calibration tool, Web-based flow clustering EI estimation system

정세웅 Se Woong Chung , 이흥수 Heung Soo Lee

DOI: Vol.27(No.1) 73-87, 2011

An abnormal mono-specific bloom of the cyanobacterium Microcystis aeruginosa had developed at a specific location (transitional zone, monitoring station of Hoenam) in Daecheong Reservoir from middle of July to early August, 2001. The maximum cell counts during the peak bloom reached 1,477,500 cells/mL, which was more than 6~10 times greater than those at other monitoring sites. The hypothesis of this study is that the timing and location of the algal bloom was highly correlated with the local environmental niche that was controled by physical processes such as hydrodynamic mixing and pollutant transport in the reservoir. A three-dimensional, coupled hydrodynamic and ecological model, ELCOM-CAEDYM, was applied to the period of development and subsequent decline of the bloom. The model was calibrated against observed water temperature profiles and water quality variables for different locations, and applied to reproduce the algal bloom event and justify the limiting factor that controled the Microcystis bloom at R3. The simulation results supported the hypothesis that the phosphorus loading induced from a contaminated tributary during several runoff events are closely related to the rapid growth of Microcystis during the period of bloom. Also the physical environments of the reservoir such as a strong thermal stratification and weak wind velocity conditions provided competitive advantage to Microcystis given its light adaptation capability. The results show how the ELCOM-CAEDYM captures the complex interactions between the hydrodynamic and biogeochemical processes, and the local environmental niche that is preferable for cyanobacterial species growth.

Algal bloom, Cyanobacteria, Daecheong Reservoir, ELCOM-CAEDYM, Microcystis

박혜경 Hae Kyung Park , 권오윤 Oh Youn Kwon , 정동일 Dong Il Jung

DOI: Vol.27(No.1) 88-97, 2011

To identify the inflow and outflow characteristics of allchthonous organic matters and examine the change of allochthonous organic matter load pattern due to the climate change, we investigated the temporal variations of DOC and POC concentrations within inflow water and dam discharge water and spatio-temporal distribution of POM within the lake water in Lake Soyang which is the largest dam reservoir in Korea in 2006. Most of allochthonous DOC flowed into the lake water during initial rain and was not affected by the amount of precipitation, whereas most of allochthonous POC flowed into during concentrated heavy rain and the concentration of POC was significantly associated with the amount of inflow water and precipitation. Calculated annual allochthonous organic matter loads in Lake Soyang from 2003 to 2006 using the regression equation between the amount of inflow water and the concentration of POC indicate allochthonous organic matter loads are mainly affected by total influx and extreme influx of inflow water. The spatio-temporal distribution of POM indicated allochthonous organic matter of inflow river during flood period in July transported from upper part to middle and lower part of the lake a month later respectively along the middle layer of water column in Lake Soyang.

Allochthonous organic carbon, Climate change, C/N ratio of POM, Lake Soyang

권수열 Soo Youl Kwon , 김영 Young Kim , Greg Roorrer , Lewis Semprini

DOI: Vol.27(No.1) 98-103, 2011

Photocatalysis using UV light and catalysts is an attractive low temperature and non-energy-intensive method for remediation of a wide range of chemical contaminants like chloroform (CF). Recently development of environmental friendly and sustainable catalytic systems is needed before such catalysts can be routinely applied to large-scale remediation or drinking water treatment. Titanium dioxide is a candidate material, since it is stable, highly reactive, and inexpensive. Diatoms are photosynthetic, single-celled algae that make a microscale silica shell with nano scale features. These diatoms have an ability to biologically fabricate TiO2 nanoparticles into this shell in a process that parallels nanoscale silica mineralization. We cultivated diatoms, metabolically deposited titanium into the shell by using a two-stage photobioreactor and used this biogenic TiO2 to this study. In this study we evaluated how effectively biogenic TiO2 nanoparticles transform CF compared with chemically-synthesized TiO2 nanoparticlesthe and effect of pretreatment of diatom-produced TiO2 nanoparticles on photocatalytic transformation of CF. The rate of CF transformation by diatom-TiO2 particles is a factor of 3 slower than chemically-synthesized one and chloride ion production was also co-related with CF transformation, and 79~91% of CF mineralization was observed in two TiO2 particles. And the period of sonication and mass transfer due to particle size, evaluated by difference of oxygen tention does not affect on the CF transformation. Based on the XRD analysis we conclude that slower CF transformation by diatom-TiO2 might be due to incomplete annealing to the anatase form.

Chloroform, Diatom-produced biogenic TiO2, Photocatalysis, Titanium dioxide

정일용 Il Yong Jeong , 차민환 Min Whan Cha

DOI: Vol.27(No.1) 104-109, 2011

The removal efficiencies of 2-methylisoborneol (MIB) and geosmin were investigated to reveal removal characteristics of typical organic compounds causing disagreeable taste and odor at the conventional water treatment plant installed with pulsator clarifier patented by the French company Degremont. The injection rate of Powdered Activated Carbon (PAC) into water was changed step wisely as we conducted jar tests in the laboratory and water treatment in the actual plant. 2-MIB concentration decreased linearly while geosmin did exponentially along with the injection rate of PAC at our jar tests. The removal efficiency of geosmin by PAC injection was considerably higher than that of 2-MIB. In the real pulsator clarifier, 2-MIB concentration started decreasing as the injection rate reached up to 10 mg/L of PAC. On the other hand, the concentration of geosmin in water decreased proportional to the injection rate of PAC. In the sand filtration, removal efficiencies of 2-MIB and geosmin on July were much higher than those on March. It was carefully suggested beforehand and found afterwards that general microorganisms notably existed in the sand filter with no chlorine in filter influent and backwash water and the sand filter biologically activated removed much more odor compounds. It was considered as the reason why the removal efficiency of 2-MIB and geosmin was increased. The microbial activity maybe increased in summer with water temperature rising and low filtration rate possibly increased contact time between odor compounds and general microorganisms.

2-methylisoborneol, MIB, Geosmin, Microorganisms, PAC, Pulsator clarifier

김대현 Dae Hyun Kim , 황수옥 Suok Hwang Hwang , 정은재 Eun Jae Jeong , 신창수 Chang Soo Shin , 유영범 Young Beom Yu , 홍승관 Seung Kwan Hong

DOI: Vol.27(No.1) 110-114, 2011

In this paper, in order to eliminate Limnoperna fortunei inhabiting the water conduction pipeline, prechlorination at the intake station was employed to improve the degradation of water quality due to the high pH of raw water taken at the downstream of Paldang Dam, algal growth, etc.. With the prechlorination concentration of 1.0mg/L at the intake station, the pH in the water well at the treatment plant decreased by 0.4, and with 1.5mg/L, by 0.6. Also, it eliminated Chlorophyll-a by about 95%, and the population of algae by about 49%. Such disinfection by-products (DBPs) as Trihalomathanes (THMs), Haloacetic Acids (HAAs), and Chloral Hydrate (CH) were under the quality standard for potable water, showing no change by the prechlorination, while raising the prechlorination rate from 1.0 up to 1.5mg/L, the DBPs in the water well increased by 1.5 to 3.1 times. As a consequence of testing Kyungan Stream, a branch stream flowing into Lake Paldang, the prechlorination (0.57mg/L, 1.14mg/L, 1.71mg/L) had no effect of eliminating the taste and odor compounds and total organic carbon (TOC) which is the DBPs precursor. As for the efficiency of Geosmin elimination by the rates of prechlorination and powder activated carbonation (PAC), it was found that the higher the concentration of PAC was (30ppm>20ppm>10ppm), the higher the efficiency was; the higher the rate of prechlorination was, the lower the efficiency by PAC was. Therefore, when taste and odor occur from raw water, suspending prechlorination at the intake or lowering the rate was proved to be more effective in eliminating the taste and odor compounds by PAC.

DBPs, Geosmin, Prechlorination, 2-MIB

최수아 Su A Choi , 최은진 Eun Jin Choi , 김동수 Dong Su Kim

DOI: Vol.27(No.1) 115-119, 2011

The mobility of groundwater in the soil environment has an important role in the soil environment and absorption of plant. Therefore, studies on the mobility of groundwater considering the physical and chemical properties of soil is very important. In this study, movement of water due to change in soil particle size were observed by capillary rise. The height of the capillaries was measured according to capillary diameter, temperature and solution concentration. The inner diameter of each capillary itself is 0.012, 0.016, 0.024, 0.027 cm, and experiments were performed at 22°C. As a result, the height of the capillaries decreased with increasing capillary diameter, and the solution temperature but increased with increasing concentration. Changes in the height of the capillaries are interpreted to related with surface tension by the Young-Laplace equation. Also on the mobility of groundwater, the increase of water and soil temperatures can be significant factors caused by ion strength and global warming as well as pores in the soil particles. The results of this study is considered to provide the basic data on the behavior of groundwater in the soil environment.

Capillary rise, Groundwater, Ionic strength, Mobility, Soil environment

방사라 Sa Ra Bang , 유근제 Keun Je Yoo , 박준홍 Joon Hong Park

DOI: Vol.27(No.1) 120-128, 2011

Korea Groundwater Quality Monitoring Network is a database of annual groundwater quality survey results to prevent groundwater pollution. We estimated contamination index (CI) values for each type of land use, and analyzed temporal trends of pollutant concentration data in the Groundwater Quality Monitoring Network from 2001 to 2009. Among the pollutants considered in the database, the concentrations of nitrate and chloride were higher than their standards. In the case of nitrate, recreation parks, golf courses and general waste dumping regions showed increasing trends according to linear regression analysis, whereas industrial complexes and residential regions of urgan and recreation parks showed increasing trends in the chloride concentration data. According to multiple variable linear regression analysis, EC, pH and topography were major factors influencing CI values. These results suggest that groundwater with a high CI value and increasing trend is vulnerable for potential contamination, which requires more careful groundwater pollution control.

Contaminant index, Groundwater pollution, Korea Groundwater Qualtiy Monitoring Network, Nitrate, Trend analysis