이태환 Taehwan Lee , 조홍래 Hong-lae Cho , 정의상 Euisang Jeong , 구본경 Bhon K. Koo , 박배경 Baekyung Park , 김용석 Yongseok Kim

DOI:10.15681/KSWE.2017.33.2.123 Vol.33(No.2) 123-129, 2017

This study intends to identify methodologies to reasonably estimate the effectiveness of road vacuum cleaning in terms of pollution loads reduction. It proposes two empirical equations for estimating how much diffuse pollution can be removed by road vacuum cleaning. The proposed equations estimate the amount of pollution loads removed by considering (a) the distance covered by road vacuum cleaning; and (b) the amount of road-deposited sediment (RDS). All the parameters in these equations were evaluated by field monitoring and laboratory analyses, except for the RDS generation rate. The results are that pollutant removal efficiency is 46.3% for BOD₅ and 56.4% for TP; the discharge ratios for particulate and dissolved BOD₅ are 35.0% and 21.2%, respectively; and the discharge ratios for particulate and dissolved TP are 35.0% and 19.4%, respectively. The average concentrations of pollutants in RDS are BOD₅ 977.3 mg/kg and TP 317.6 mg/kg. A case study seems to show that both equations could be useful if the adopted parameters are reasonably evaluated. In particular, the RDS generation rate should be evaluated by means of monitoring data collected from various road conditions.

Diffuse pollution loads, Road deposited sediment(RDS), Road vacuum cleaning efficiency, Wash-off rates of RDS

송상환 Sanghwan Song , 박종환 Jonghwan Park , 강태우 Tae-woo Kang , 김영석 Young-suk Kim , 김지현 Jihyun Kim , 강태구 Taegu Kang

DOI:10.15681/KSWE.2017.33.2.130 Vol.33(No.2) 130-139, 2017

In order to evaluate the accuracy of real-time measurement of cyanobacterial fluorescence needed to predict cyanobacterial blooms, this research examined 357 pairs of data (from 2013-2016) consisting of both microscopic toxic cyanobacterial cell counts and concurrent real-time cyanobacterial concentrations, from two sites (YS1 and YS2) in the Yeongsan river. The high level of real-time cyanobacterial concentration was associated with exceeding 5,000 cyanobacterial cells/ml (odds ratio [OR] 1.07, 95% confidence interval [CI] 1.03-1.12) and 10,000 cells/ml (OR 1.08, 95% CI 1.04-1.12) at YS2 site. The area under the receiver operating characteristic (ROC) curve for the real-time cyanobacterial measurement at the YS2 site was 0.93; hence the measurement provides a highly accurate detection of cyanobacterial blooms. On the ROC curve, the early alert levels of real-time cyanobacteria ranging from 16 to -23 μg chl-a/L would produce an acceptable sensitivity of 79% and specificities greater than 90%. The real-time fluorescence measurement was an accurate indicator of cyanobacteria and can serve as a tool for detecting toxic cyanobacterial bloom events in the Yeongsan river.

Alert level, Cyanobacteria, Real-time measurement, Receiver operating characteristic

유광태 Kwangtae You , 김종락 Jongrack Kim , 윤주환 Zuhwan Yun , 박기정 Gijung Pakt

DOI:10.15681/KSWE.2017.33.2.140 Vol.33(No.2) 140-148, 2017

An important factor in determining the design and, therefore, the efficiency of wastewater treatment plants (WWTPs) is the influents` quantity and quality. Detailed and accurate information is essential for process control, diagnosis, and operation. In designing a plant, the optimal capacity of each bioreactor must be determined. Probabilistic models are used to predict the wastewater quantity and quality of WWTPs, which are widely used to improve plant designs and operations. In this study, the optimal probability distribution of time series data was derived to predict the influent`s water quantity and quality. Wastewater data were generated using a Monte Carlo simulation. In addition, we estimated various alternatives for the improvement of bioreactor operations based on present operation conditions, using the generated influent data and the activated sludge model, and suggested an alternative for an optimally effective plant operation. Since the influent quantity and quality were highly correlated with the actual operation data, the WWTPs` real influent characteristics were well reproduced. Adopting this suggested alternative will improve the operating conditions of WWTPs and an improvement plan for the current tele monitoring system`s effluent quality standards can be proposed.

Activated Sludge Process, ASM Model, Monte Carlo simulation, Probability Density Function, Wastewater Influent

박금주 Keumjoo Park , 이창희 Chang-hee Lee , 여형범 Hyoung Beom Yeo , 주용기 Yung-ki Ju , 김억수 Eoksu Kim , 문슬기 Seul-ki Mun

DOI:10.15681/KSWE.2017.33.2.149 Vol.33(No.2) 149-159, 2017

After an artificial barrage was constructed in 1990s, the Geumgang estuary has been experiencing considerable changes in nature as well as in socioeconomic conditions and culture in villages in the vicinity. In order to understand how the change in estuarine environment brings about conflicts among the local communities and to resolve the conflicts, this research investigated the causes of conflicts in the Geumgang estuary using the in-depth and semi-structured interview method. One hundred local people who have lived in the vicinity of the Geumgang estuary for more than 30 years were selected for the interviews. Results of the research show that local people`s jobs determine the opinions about the estuary barrage and the way of estuarine management. Gaining an understanding of the environmental change and local conflicts can help to develop a sustainable and integrated estuary management system in the region.

Conflicts, Geumgang Estuary, Qualitative Data, Semi-structured Interview

한정호 Jeong Ho Han , 이동준 Dong Jun Lee , 강부식 Boosik Kang , 정세웅 Se Woong Chung , 장원석 Won Seok Jang , 임경재 Kyoung Jae Lim , 김종건 Jonggun Kim

DOI:10.15681/KSWE.2017.33.2.160 Vol.33(No.2) 160-169, 2017

One objective of this study is to analyze changes in the future rainfall patterns in the Soyang-dam watershed according to the RCP 4.5 scenario of climate change. A second objective is to project peak flow and hourly sediment simulated for future extreme rainfall events using the SWAT model. For these, the accuracy of the SWAT hourly simulation for the large-scale watershed was evaluated in advance. The results of the model calibration showed that the simulated peak flow matched observation well within the acceptable average relative error. The results of our analysis of future rainfall pattern changes indicated that extreme storm events will become more severe and frequent as climate change progresses. We especially could see that large-scale extreme storm events may become more severe and more frequent during 2030-2040 and 2050-2060. In addition, as shown in the SWAT hourly simulation for future extreme storm events, flooding and turbid water could be even worse in the future than with the most devastating storm event in the past, as happened with the typhoon Ewiniar in 2006. Thus, countermeasures against future extreme storm events and turbid water are needed to cope with climate change.

Climate change, Extreme storm event, Hourly simulation, Sediment, SWAT, Streamflow

테킬안디넷 Andinet Tekile , 김일호 Ilho Kim , 이재엽 Jai-yeop Lee

DOI:10.15681/KSWE.2017.33.2.170 Vol.33(No.2) 170-180, 2017

This study used jet water flow, ultrasonication, and ozonation units to investigate the impact of the unit components on the water quality of the stagnant Yeo-cheon River in Korea. Samples were collected at six locations, before the experiment and at 1, 3, and 6 hrs afterward. By operating the water-flow unit only, dissolved oxygen increased by as much as 90% after 3 hrs, 25 m downstream from the device, and Chi-a was reduced by 80%. With sonication added, more than 80% of the ChI-a was removed, even at 100 m downstream from the device. In addition, total dissolved phosphorus was reduced from an average value of 420 (± to μg/L before ultrasonic irradiation to 160 (±40) \μ/L afterward. By releasing ozone into the flow with sonication, ChI-a was greatly removed from the water column, and ammonia nitrogen also decreased, to an average value of 20 n column 60 μg/L. However, because only 3*10-3 mg/L of ozone was used for safety reasons, and because of its brief reaction time, the effect of integrating ozone into the system covered only a small area. Generally, combining sonication with jet flow is promising for preventing algal bloom formation, because it effectively removed Chi-a from the water column.

Algal bloom, Jet flow, Ozone, Stagnant, Ultra-sonication, Water quality

김종민 Jongmin Kim , 신기식 Kisik Shin , 이정서 Jungseo Lee , 이택준 Taekjune Lee

DOI:10.15681/KSWE.2017.33.2.181 Vol.33(No.2) 181-186, 2017

This paper aimed to evaluate the results of an altemative acute toxicity test on 83 wastewater samples. Each sample was tested by a traditional method (laboratory-cultured D. magna as test organisms) and an alternative method (Toxkit, purchased from a specialized company, MicroBioTests Inc., Mariakerke [Gent], Belgium). The relationship between the laboratory-cultured toxicity and Toxkit`s toxicity indicated a strong relationship (r<sub>2</sub> =.84, P < .01, N = 83). The number of samples which displayed a small difference of less than .5 between the two test methods was 52 and accounted for 63% of the collected samples. In addition, these 52 samples exhibited a low average toxicity of TU .5 (laboratory culture method) and TU .45 (Toxkit`s method), whereas samples with big differences between the two methods` results displayed a tendency of higher toxicities. These results indicate that the alternative toxicity test method can be applied if samples have a toxicity of less than TU 2. Also, Toxkit`s test results displayed EC₅₀ values between 0.93 and 1.68 mg/L which can be considered to conform with quality control standard.

Alternative test method, D. magna, Toxkits, Wastewater

노유래 Yoorae Noh , 박준홍 Joonhong Park

DOI:10.15681/KSWE.2017.33.2.187 Vol.33(No.2) 187-196, 2017

To ensure the hygienic safety of drinking water in a water storage tank, the concentrations of residual chlorine should be above a certain regulated level. In this study, we conducted model simulations to investigate the effects of temperature on residual chlorine under water storage tank conditions typical for use in Seoul. To this effect, model parameter values (decomposition rate constant, sorption coefficient, and evaporation mass transfer coefficient) were determined in laboratory experiments. The model simulations under continuous flow conditions showed that the residual chlorine concentrations satisfied the Korea ministry of environment`s water quality standard level (0.1 mg/L) at all temperature conditions (5°C, 10°C, 15°C, 20°C, and 25°C). When the tanks were in a no-flow condition (i,e., no tap-water influent due to a sudden shut-down), the concentrations lowered relative to the water quality regulatory level. The findings of simulating Seoul`s water storage tanks also suggested that the disappearance rate of residual chlorine could be reduced by the tanks` design optimization with maintenance of low water temperature, minimization of air flow and volume, suppression of water dispersion, and the use of wall materials with low sorption ability.

Bulk decomposition, Evaporation, Residual chlorine, Sorption, Temperature, Water storage tank

김종민 Jongmin Kim , 신기식 Kisik Shin , 이수형 Soohyung Lee , 이정서 Jungseo Lee , 이택준 Taekjune Lee

DOI:10.15681/KSWE.2017.33.2.197 Vol.33(No.2) 197-202, 2017

This paper aimed to evaluate the test results of acute toxicity on effluents which were exempted from the application of ecotoxicity criteria. A total 316 effluent samples exempt from ecotoxicity regulation control were tested. The ratio of effluent samples which exceeded the ecotoxicity criteria (TU > I) was 23.7 %, a little bit higher than in a previous similar study (22.7 %). on effluent samples which were controlled under ecotoxicity criteria. This means that our ecotoxicity management system is inappropriate and applications of ecotoxicity criteria to all effluents (82 industriy categories) needed to improve our ecotoxicity system. Given this background, the same numeric criteria (TU I or 2) for 82 industry categories were proposed. The ratio of effluent samples which exceeded the ecotoxicity criteria (TU > I) with D. magna was 23.7 %, but V. flscheri displayed 14.6 %. As an acute toxicity organism, D. magna seemed to be more sensitive than V.flscheri. The ratio of samples which exceeded TU I with D. magna during 24 h exposure was 35 % and after 48 h 41 %.

Ecotoxicity criteria, Effluent, D. magna, V. fischeri

양윤철 Yoon-cheol Yang , 이대행 Dae-haeng Lee , 이경석 Kyung-seog Lee , 안상수 Sang-su An , 송형명 Hyeong-myeong Song , 이세행 Se-haeng Lee , 윤상훈 Sang-hoon Yoon , 김선정 Sun Jung Kim , 전홍대 Hong-dae Jeon , 조영관 Young-gwan Cho , 서광엽 Gwan

DOI:10.15681/KSWE.2017.33.2.203 Vol.33(No.2) 203-210, 2017

This study was performed to verify the replacement of COD with TOC, which is more accurate and reliable in analysis, as the water quality pollution index, and to investigate the characteristics of water quality and the correlations among organic matter, suspended solids and nutrient materials from 2012 to 2015. The oxidation rates were compared by calculating the values of BOD-C/TOC and COD-C/TOC. The average value of TOC was 3.4 mg/L (range, 1.1 - 8.0 mg/L) at 14 sites during the period. The ratios of BOD-C/TOC and COD-C/TOC, that indicate the resolvability amounts among all carbon materials, were 28.8% and 62.7%, respectively. The correlation coefficient of TOC to COD at all sites was 0.718 (p<0.01), the highest value on comparing all items. The correlation coefficient of TOC to COD in the Gwangju stream was 0.753 (p<0.01), which was the highest compared to the values in other rivers. The correlation coefficient of TOC to COD was 0.757 (p<0.01) at all sites in the range of TP-III (0.1≤TP), and the correlation coefficient value was 0.762 (p<0.01) in the range of TN-II (2.0≤TP<3.0). As a result, TOC can be used as a water pollution index of organic matter instead of COD.

COD_Mn, Correlation Coefficient, Oxidation Rate, TOC, Water Pollution Index

김태경 Tae-gyung Kim , 박복성 Bog-soung Park , 정용준 Yong Jun Jung

DOI:10.15681/KSWE.2017.33.2.211 Vol.33(No.2) 211-218, 2017

This experiment was carried out with the aim of testing cadmium adsorption abilities of multi-wall carbon nanotube (MWCNT), activated carbon, and synthesized layered double hydroxide (LDH). In the acidic condition, only MWCNT was effective in removing cadmium ion from the aqueous phase while other adsorbents rarely removed cadmium ion. The MWCNT and cadmium ion adsorption reactions followed a pseudo first-order kinetic. When the initial pH value was neutral (pH = 7), cadmium ion was rapidly removed by MWCNT and activated carbon in 4 hr (100% and 99.2%, respectively). Increasing adsorbent dosage affects the pH evolution and cadmium ion removal (0 to 99%). Cytotoxicity test showed that both MWCNT and LOH had low cytotoxic effects on three kinds of human cells (A549, HS-294t, and HT-29).

Activated carbon, Adsorption, Cadmium, CNT, Cytotoxicity, LDH

신창민 Chang Min Shin , 민중혁 Joong-hyuk Min , 박수영 Su Young Park , 최정규 Jungkyu Choi , 박종환 Jong Hwan Park , 송용식 Young Sik Song , 김경현 Kyunghyun Kim

DOI:10.15681/KSWE.2017.33.2.219 Vol.33(No.2) 219-229, 2017

A watershed-river linked modeling system was developed to forecast the water quality, particularly weekly changes in chlorophyll-a concentration, of the Yeongsan River, Korea. Hydrological Simulation Program-Fortran (HSPF) and Environmental Fluid Dynamics Code (EFDC) were adopted as the basic model framework. In this study, the EFDC model was modified to effectively simulate the operational condition and the flow of multi-functional weirs constructed in the main channel of rivers. The model was tested against hydrologic, water quality and algal data collected at the right upstream sites of two weirs in 2014. The mean absolute errors (MAEs) related to model calibration in the annual variations of the river stage, TN, TP, and algal concentration were 0.03 - 0.10 m, 0.65 - 0.67 mg/L, 0.03 - 0.04 mg/L, and 9.7 - 10.8 mg/m³, respectively. On the other hand, the MAE values of forecasting results for the chlorophyll-a level at the same sites in 2015 ranged from 18.7 to 22.4 mg/m³, which were higher than those for model calibration. Increased errors in forecasting were mainly attributed to higher uncertainties in weather forecasting data compared to the observed data used for model calibration.

Chlorophyll-a, EFDC, Forecast, HSPF, Yeongsan, Weir