노성유 Sung Yu Noh , 박혜경 Hae Kyung Park , 최희락 Hee Lak Choi , 이재안 Jae An Lee

DOI:10.15681/KSWE.2014.30.4.377 Vol.30(No.4) 377-385, 2014

To study the fluctuations and relationship in climate change, environmental factors and cyanobacteria communities, we investigated Chudong station of the Daechung reservoir. The average annual temperature showed the maximum value (13.9°C) from 1994, showed a gradually increasing pattern from 1969 to 2010 in the Daechung reservoir. The number of days with temperatures over 20°C, minimum temperature of the year and average temperature of the winter season patterns also showed a significant increase. The long-time changed in the annual precipitation were not showed a significant variation. The water temperature record comparatively high value in summer, declined in winter. At all period, the phytoplankton were highest biomass in July 2000, and then, showed comparative higher biomass in the summer months. Cyanobacteria taxa were also showed more than 50%. Emergence of cyanobacteria also appeared in November 2007, were prolonged emergence. The dominant genera of taxa were the dominant sphere (Microcystis spp.) until early 2000. After that, the dominant species were the dominant linear (Aphanizomenon spp., Anabaena spp.). Cyanobacteria were the most correlated with water temperature (r= 0.341, p<0.01) and phosphate concentration (r = 0.355, p<0.01).

Chudong, Climate change, Cyanobacteria, Daecheong reservoir

최희정 Hee Jeong Choi

DOI:10.15681/KSWE.2014.30.4.386 Vol.30(No.4) 386-393, 2014

The aim of this study was to investigate the nutrient removal and biomass productivity in the wastewater using MMBR (Microalgae Membrane Bioreactor). MMBR process was combined OPPBR (Optical Panel Photobioreactor) and MBR (Membrane bioreactor). The OPPBR and MBR were operated 3 days and 9h HRT (Hydraulic retention time), respectively, using microalgae as Chlorella vulgaris. The obtained result indicated that the biomass productivity of 0.498 g/L/d with light transmittance of 92% at a 305 mm depth in the OPPBR was achieved. The total consumption of BOD (Biochemical Oxygen Demand) and COD (Chemical Oxygen Demand) in the MMBR were found to be 97.56% and 96.06%, respectively. Additionally, the removal of TN, NO3-N, TP and PO4-P were 94.94%, 91.04%, 99.54% and 93.06% in MMBR, respectively. These results indicated that the MMBR process was highly effective for COD, BOD and nutrient removal when compared to the separate OPPBR or MBR process. The MMBR process was effective for nutrient removal and biomass productivity and can be applied to treat wastewater in sewage treatment plant.

Biomass, Microalgae Membrane Bioreactor, MMBR, Nutrient removal, Wastewater, Optical panel photobioreactor

김동석 Dong Seong Kim , 박영식 Young Seek Park

DOI:10.15681/KSWE.2014.30.4.394 Vol.30(No.4) 394-402, 2014

High-voltage dielectric discharges are an emerging technique in environmental pollutant degradation, which are characterized by the production of hydroxyl radicals as the primary degradation species. The initiation and propagation of the electrical discharges depends on several physical, chemical, and electrical parameters such as 1st and 2nd voltage of power, gas supply, conductivity and pH. These parameters also influence the physical and chemical characteristics of the discharges, including the production of reactive species such as ·OH, H2O2 and O3. The experimental results showed that the optimum 1st voltage and oxygen flow rate for RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical) degradation were 160 V (2nd voltage of is 15 kV) and 4 L/min, respectively. As the 2nd voltage (4 kV to 15 kV) was increase, RNO degradation was increased and, generated H2O2 and O3 concentration were increased. The conductivity of the solution was not influencing the RNO degradation, H2O2 and O3 generation. The pH effect on RNO degradation was not high. However, the lower pH and the conductivity, the higher H2O2 and O3 generation were observed.

Dielectric barrier discharge, H2O2, O3, OH radical, Oxidants, Plasma

정현 Hyun Jung , 박숙현 Soo Khyun Park , 황유식 Yu Sik Hwang

DOI:10.15681/KSWE.2014.30.4.403 Vol.30(No.4) 403-408, 2014

The toxicity of heavy metals (Zn, Pb) and diesel, in single and binary solution was investigated using the photobacterium Vibrio fischeri (Microtox test) as a test organism. In this experiment, the concentration of water soluble fraction of diesel was based on the total petroleum hydrocarbon (TPH). The toxicity of each single compound showed the following EC50 (15min): Zn 1.90 mg/L, Pb 0.31 mg/L, TPH 2.09 mg/L. The observed toxicity of binary mixtures increased, depending on the concentration of the mixed substance. The effects were defined as synergistic, antagonistic, or additive, in accordance with the sign of difference between the predicted and observed toxicity at binary mixtures. The interactive effects between zinc and lead were synergistic, on the other hand, antagonistic and additive effects were found in each metal and TPH mixtures on the bioluminescence of V. fischeri.

Diesel, Heavy metal, Interactive effect, Lead, Vibrio fischeri, Zinc

강태구 Tae Gu Kang , 이혁 Hynk Lee , 강일석 Il Seok Kang , 허태영 Tae Young Heo

DOI:10.15681/KSWE.2014.30.4.409 Vol.30(No.4) 409-417, 2014

Spatial prediction methods have been useful to determine the variability of water quality in space and time due to difficulties in collecting spatial data across extensive spaces such as watershed. This study compares two kriging methods in predicting BOD concentration on the unmonitored sites in the Geum River Watershed and to assess its predictive performance by leave-one-out cross validation. This study has shown that cokriging method can make better predictions of BOD concentration than ordinary kriging method across the Geum River Watershed. Challenges for the application of cokriging on the spatial prediction of surface water quality involve the comparison of network-distance-based relationship and euclidean-distance-based relationship for the improvement in the predictive performance.

Geostatistics, Kriging, Nugget, Sill, Variogram, Water quality

류지철 Ji Chul Ryu , 안기홍 Ki Hong Ahn , 한미덕 Mi Deok Han , 황하선 Ha Sun Hwang , 최재완 Jae Wan Choi , 김용석 Young Seok Kim , 임경재 Kyoung Jae Lim

DOI:10.15681/KSWE.2014.30.4.418 Vol.30(No.4) 418-428, 2014

The purpose of this study is to predict the spatio-temporal changes in land uses and to evaluate land-based pollutant loads in the future under Total Water Pollution Load Management System using CLUE-S model. For these ends, sensitive parameters of conversion elasticities in CLUE-S model were calibrated and these calibrated parameters of conversion elasticities, level II land cover map of year 2009, and 7 driving factors of land use changes were used in predicting future land uses in 2002 with two scenarios(Scenario 1: non area restriction, Scenario 2: area restriction). This projected land use map of 2020 was used to estimate land-based pollutant loads. It was expected that urban areas will increase in 2020 from both scenarios 1 and 2. In Scenario 1, urban areas are expected to increase within greenbelt areas and deforest would be expected. Under Scenario 2, these phenomena were not expected. Also the results of estimation of BOD and TP pollutant loads, the BOD difference between scenarios 1 and 2 was 719 kg/day in urban areas and TP difference was 17.60 kg/day in urban areas. As shown in this study, it was found that the CLUE-S model can be useful in future pollutant load estimations because of its capability of projecting future land uses considering various socio-economic driving factors and area-restriction factors, compared with conventionally used land use prediction model.

Area restriction, Driving factor, Land use change, Land pollutant load

공동수 Dong Soo Kong

DOI:10.15681/KSWE.2014.30.4.429 Vol.30(No.4) 429-440, 2014

This study was conducted to investigate the main cause of water quality deterioration during the spring season in the transition zone between the South Han River and the river-reservoir Paldang. A water quality model modified from QUAL2E (U.S.EPA) was used, and the model showed that eutrophication and algal production in the low flow season affected about 60% of the organic pollution at the downstream of the South Han River. This result means that phosphorus control is prior to external organic material management to ameliorate the deterioration of water quality in the water body.

Eutrophication, Transition zone, Water quality, Water quality modeling

최윤호 Youn Ho Choi , 박윤식 Youn Shik Park , 류지철 Ji Chul Ryu , 이동준 Don June Lee , 김용석 Yong Seok Kim , 최중대 Joong Dae Choi , 임경재 Kyoung Jae Lim

DOI:10.15681/KSWE.2014.30.4.441 Vol.30(No.4) 441-451, 2014

Streamflow is typically divided into two components that are direct runoff and baseflow, it is required to analyze and estimate behaviors of those two flow components to understand watershed characteristics so that watershed management plan can be effective in pollutant reductions. Since pollutant load behaviors in a stream or river are variable by flow component behaviors, best management practices need to be applied in a watershed based on the pollutant load behaviors varying with flow components. Thus, baseflow behaviors were analyzed separating baseflow from streamflow data collected from fifteen streamflow gaging stations in the 4 major river watersheds which are the Han river, Nakdong river, Guem river, and Yeongsan·Somjin river watersheds. Moreover, precipitation trends throughout the 4 River Systems were investigated, thus daily precipitation data were collected from sixty-five locations. The Hank river watershed displayed the largest precipitation (925.2 mm) in summer but the lowest precipitation (71.8 mm) in winter, indicating the watershed has the most fluctuating precipitation characteristic. While the precipitation trends in the Four River Systems varied, a distinct feature in baseflow trends was not found, moreover baseflow percentages to streamflow were typically greater than 50% in the Four River Systems. As shown in this study, it would be expected significant amount of pollutants could be contributed to the stream in the form of baseflow at the watershed.

Baseflow, Direct runoff, Pollutant load, Separating baseflow, Streamflow