박혜진 Hye Jin Park , 김상훈 Sang Hoon Kim , 박상우 Woo Sang Park , 이재윤 Jae Yoon Lee , 이재안 Jae An Lee

DOI:10.15681/KSWE.2014.30.3.261 Vol.30(No.3) 261-268, 2014

Four clays (both natural and commercial types) mainly used in Korea were tested for removal efficiency of Microcystis spp. and ecotoxicity on Daphnia magna and Vibrio fischeri. Four clays (clay A~D) were composed of 91.9~100% of sand (0.02~0.2 mm in particle size). Clay D consisted of lager particles than other clays. Major elements of the four clays were SiO2 (45.3~62.8%), Al2O3 (18.5~29.7%) and Fe2O3 (5.4~7.9%). They contained kaolinite (clay mineral), quartz, muscovite, and so on. Clay C and D contained montmorillonite, one of the clay minerals improving clay-cell aggregation. For clay A, B and C, removal efficiency of Microcystis spp. was over 60% at 2 g/L. It reached about 100% at over 5 g/L. For clay D, it was over 60% and 95~100% at 5 g/L and 20 g/L respectively. After adding clays, pH decreased. The greatest drop of pH appeared at clay C. Except for addition of 100 g/L clay C, ecotoxicity on D. magna and V. fischeri didn’``t appeared at all dose of clays.

Clay, Daphnia magna, Ecotoxicity, Microcystis, Removal efficiency, Vibrio fischeri

유광태 Kwang Tae Yoo , 김종락 Jong Rack Kim , 윤주환 Zuw Han Yun , 황호재 Hojae Hwang , 이한샘 Han Saem Lee , 김성표 Sung Pyo Kim

DOI:10.15681/KSWE.2014.30.3.269 Vol.30(No.3) 269-282, 2014

The objective of this study is to find out whether the developed semi-empirical biofilm model can be applicable to real BAF pilot-scale wastewater treatment. In addition, the optimum operating conditions of BAF as a function of process variables such as organic loading change can be drawn based on the simulation results of model. The results will provide the economic and efficient BAF process design and operating control. As a result, developed semi-empirical biofilm model which is relatively simple compared to mathematical model can simulate three BAF processes consisted of 25 layers within 1 seconds. When this model was used for simulating real pilot scale BAF process and the simulated water quality values were compared to experimental ones, simulated TCOD, SCOD, TN, NH4 +-N, NOx --N, alkalinity values were different to experimental ones within 21%, 20%, 8.1%, 48%, 10%, and 23%, respectively. Therefore, if the BAF system was equipped with automatic control, the BAF process can be better efficiently adapted under the condition of significant change of influent loading.

Biological aerated filter, semi-empirical biofilm model, simulation, wastewater treatment

조인환 In Hwan Cho , 황순진 Soon Jin Hwang , 김백호 Baik Ho Kim , 김용재 Yong Jae Kim

DOI:10.15681/KSWE.2014.30.3.283 Vol.30(No.3) 283-291, 2014

To study the distribution characteristics of diatom communities in relation to the gradient of water quality and land-use, water samples and epilithic diatoms were collected from 90 sites including mainstream and tributaries, in the Geum River System (GRS) during no rainfall, May 2011. Of 239 taxa identified, Achnanthes convergens and Cymbella minuta were dominated over all the sites. Cluster analysis on the GRS divided into three groups. Group 1 (G1) is the mountainous upstream, a relatively good water quality, and mainly consisted of saproxenous species. Group 2 (G2) is the urban sites, polluted (high in electric conductivity, total phosphate and soluble reactive phosphorus), and saproxenous and common species. Group 3 (G3) is the agriculture sites, and polluted (turbidity, total nitrogen, nitrate), and saprophilous species. There were some discrepancies between abiotic and biotic variables in GRS; biologically similar between G1 and G2, but abiotically similar between G2 and G3. These differences may attribute to not only physiological characteristics of diatom cells, but complicate relationships between microhabitat and water quality. Thus, an urgent development of generalized or standardized methods to diminish the differences between epilithic diatom community and environments is advent.

Cluster Analysis, Epilithic Diatom, Geum River System, Indicator Species Analysis, Land-use, Water Quality

장준원 Jun Won Jang , 김혜란 Hye Ran Kim , 임형석 Hyeong Seok Lim , 박재우 Jae Woo Park

DOI:10.15681/KSWE.2014.30.3.292 Vol.30(No.3) 292-297, 2014

We synthesized the self-organized nanoporous oxide with potentiostatic anodization of iron foil. The iron oxide nanocomposite (INCs) were fabricated in 1M Na2SO4 containing 0.5wt% NaF electrolyte holding the potential at 20, 40 and 60 V for 20min, respectively. Field Emmision Scanning Electron Microscopy (FESEM) and X-ray Diffractometer (XRD) were used to evaluate the micromorphology and crystalline structure of INC film. Also, this study was performed to evaluate the fenton reaction using INC film with hydroperoxide for degradation of cyanide dissolved in water. In case of INC-40V in the presence of H2O2 3%, the first-order rate constant was found to be 1.7 × 10-2 min-1, and indicated to be 1.2 × 10-2 min-1 on commercial hematite powder. This result is shown to be good performance enough to replace the powder type for treatment of wastewater.

Anodization, Cyanide, Fenton process, Iron oxide nanocomposite (INC), Plating wastewater

이준철 Jun Cheol Lee , 박대원 Dae Won Park

DOI:10.15681/KSWE.2014.30.3.298 Vol.30(No.3) 298-303, 2014

We measured by electrochemical method for TRC (total residual chlorine) in ocean. From the results of Au electrode used for working electrode through cyclic voltammetry test, we obtained charge in voltage ranged from 0.0V-1.0V, and analyzed correlations of charge for TRC. Reduction peak TRC was investigated to be approximately 0.65 V vs. Ag/AgCl, and in the case that salt concentrations and temperatures in ocean appeared different, charge was analyzed for being different in the same TRC. However, in the case that each condition was constant, charge was measured at highly correlations for TRC.

Au electrode, Chronocoulometry, Electroanalytical method, Linear sweep voltammetry, Total residual chlorine

이준철 Jun Cheol Lee , 박대원 Dae Won Park

DOI:10.15681/KSWE.2014.30.3.304 Vol.30(No.3) 304-310, 2014

The conventional methods for total residual chlorine such as iodometry and DPD colorimetric can cause secondary pollution due to additional agents, also have a wide error range. As for alternative, electrochemical method can measure TRC(Total residual chlorine), and is not required as additional agents, also very suitable for using the fields of ballast water because test time is relatively fast. Therefore, this study was investigated for changing charge by agitation, salt concentration, and temperature change. Charge showed differences based on changes of reduction peak with or without agitation. In contrast, TRC and charge were well correlated in constant agitation speed. As TRC and charge were analyzed with high correlations in constant salinity and temperature of ocean, thereby conductivity was firstly measured, and charge had high correlation for TRC in spite of changing salinity and temperature Pt electrode revealed high reliability (r2 = 0.960) because it was rarely effected by TRC, On the other hand, Au electrode appeared inadequate (r2 = 0.767) to use sensor in less than 1.0 ppm of TRC. For high accuracy and detection of TRC, Pt and Au electrodes for test time were, respectively, 14 and 22 seconds. As a result, Pt electrode was more valuable than Au electrode in terms of response time.

Chronocoulometry, Electroanalytical method, Pt electrode, Total residual chlorine

박선재 Seon Jai Baik , 조정민 Jung Min Jo , 송현우 Hyun Woo Song , 한입섭 Lhn Sup Han

DOI:10.15681/KSWE.2014.30.3.311 Vol.30(No.3) 311-318, 2014

The purpose of this study is to investigate the effect of various types of coagulant on dewaterability and settleability of sewage sludge for the application of dewatering process. Cationic organic coagulants and inorganic coagulants of the aluminium base were used; PAC (Poly Aluminium chloride, Al2O3 17%) and C-210P (0.2%). After Jar test, PAC 26 mg/L and 0.2% C-210P 55 mg/L was decided as the optimum concentration of the coagulant according to zeta potential measurement. pH, alkalinity and viscosity were measured in all experiments and the data on sedimentation characteristics is analyzed by SDI, SVI sedimentation rate and solid flux. The SRF(Specific Resistance of Filtration) experiment was conducted with the result of single and dual injection system as the dewaterability experiment. As a result, the organic coagulant making large floc has good characteristics of sedimentation and agglutination. Also, it is observed that the organic coagulants injection has a better dewaterability efficiency of coagulants under the condition of the lowest SRF value, followed by dual and inorganic coagulants injection.

Coagulation, Dewaterbility, Floc, Sedimentation, Sludge

김해정 Hae Jung Kim , 조홍래 Hong La Echo , 구본경 Bhon Kyoung Koo

DOI:10.15681/KSWE.2014.30.3.319 Vol.30(No.3) 319-328, 2014

Dorang - the Korean term for headwater streams - occupy a large portion of the total stream length in a basin, and contribute significantly towards the quantitative and qualitative characteristics, and the ecosystem, of the main river. The Ministry of Environment of South Korea has supported the investigation of the status of Dorang in the nation’``s four major basins, since 2007. Without a widely accepted academic or legal definition of Dorang, however, there are limits to understand the distribution of Dorang at the national scale and to systematically compile a Dorang database. This paper, through a review of the stream classification system and Korean legal system delineating streams, defines Dorang as 1st and 2nd order streams according to the Strahler ordering method, in a 1:25,000 geographical scale. Analysis of the Geum River basin, with this definition, reveals that the total length of Dorang is 20,622.4 km (73.6% of total stream length), and the number of Dorang catchments is 23,639 (71.3% of the basin area). Further analysis of the geomorphological characteristics of Dorang catchments shows that the average total stream length is 1.1 km, average catchment length is 1.2 km, average drainage area is 0.4 km2, and average drainage density is 3.08/km.

Definition of Dorang, Headwater, Hydrologic analysis, Stream classification

이혁 Hyuk Lee , 남기범 Gi Beom Nam , 강태구 Tae Gu Kang , 윤승준 Seung Joon Yoon

DOI:10.15681/KSWE.2014.30.3.329 Vol.30(No.3) 329-339, 2014

This study aims to estimate chlorophyll-a concentration in rivers using multi-spectral RapidEye imagery and Spectral Mixture Analysis (SMA) and assess the applicability of SMA for multi-temporal imagery analysis. Comparison between images (acquired on Oct. and Nov., 2013) predicted and ground reference chlorophyll-a concentration showed significant performance statistically with determination coefficients of 0.49 and 0.51, respectively. Two band (Red-RE) model for the October and November 2013 RapidEye images showed low performance with coefficient of determinations (R2) of 0.26 and 0.16, respectively. Also Three band (Red-RE-NIR) model showed different performance with R2 of 0.016 and 0.304, respectively. SMA derived Chlorophyll-a concentrations showed relatively higher accuracy than band ratio models based values. SMA was the most appropriate method to calculate Chlorophyll-a concentration using images which were acquired on period of low Chlorophyll-a concentrations. The results of SMA for multi-temporal imagery showed low performance because of the spatio-temporal variation of each end members. This approach provides the potential of providing a cost effective method of monitoring river water quality and management using multi-spectral imagery. In addition, the calculated Chlorophyll-a concentrations using multi-spectral RapidEye imagery can be applied to water quality modeling, enhancing the predicting accuracy.

Chlorophyll-a concentration, Minimum noise fraction, MNF, Pixel purity index, PPI, RapidEye imagery, Spectral mixture analysis, SMA

곽근호 Geun Ho Kwak , 김계현 Kye Hyun Kim , 이철용 Chol Young Lee , 오성광 Seong Kwang Oh

DOI:10.15681/KSWE.2014.30.3.340 Vol.30(No.3) 340-350, 2014

Recently, TMDL has been implemented to estimate the amount of pollutant loads and to establish proper mitigation strategy to decrease the pollutant loads by the Ministry of Environment. To estimate the amount of pollutant loads with reasonable accuracy, securing landcover map with periodically updating is essential. However, in reality, due to the technical and financial difficulties, the landcover map has not been updated annually. Hence, this study mainly aims to suggest an effective GIS-based updating method in order to promote utilization of landcover map in the estimation of pollutant loads. Bupyeong-gu at the City of Incheon with the total area of 31.98 km2 was chosen for this study and spatial data including digital topographic maps, ortho aerial photo, and satellite images were collected and utilized. A total of 7,235 feature entities were newly produced through the updating process of five steps and it was revealed that the classification of landcover with the total area of 3.34 km2 was to be changed. The validity and feasibility of the suggested method were proved with the accuracy of 97.9% from the field verification. Further study needs to be made for devising more automated method to update landcover map to facilitate TMDL for individual local governments.

Geographic Information System, GIS, Landcover Map, Nonpoint Source Pollution, Total Maximum Daily Loads, TMDL

박준대 Jun Dae Park , 오승영 Seung Young Oh , 김용석 Yong Seok Kim

DOI:10.15681/KSWE.2014.30.3.351 Vol.30(No.3) 351-360, 2014

The allocation of margin of safety (MOS) at a uniform rate to all areas of the unit watershed makes it very difficult to keep the load allotment stable in the area for lack of reduction measures like forest land. This study developed an equation to calculate margin of safety differentially according to the regional characteristics. The equation was formulated on the basis of the regional characteristic factors such as a load contribution factor for land use type and a site conversion factor for the unit watershed. The load contribution factor represents a contribution of loads from a particular land use. The site conversion factor was derived from the site conversion ratio of a unit watershed. Margin of safety for the non-point pollution load in the land use sector decreased by 20~25% in three river basins. The margin of safety in the unit watersheds with low site occupation ratios decreased in high rate, while in the unit watersheds with large urban area decreased in low rate. With the application of the differential margin of safety considering regional characteristics, not only the reduction of pollution loads can become lighter but also it can be easier to develop plans for Total Maximum Daily Loads (TMDLs) even where the reduction measures are not available.

Allocation, Load contribution factor, Margin of safety, Regional characteristics, Site conversion factor, Total Maximum Daily Loads