최정현 Jeonghyeon Choi , 이옥정 Okjeong Lee , 김용석 Yongseok Kim , 김상단 Sangdan Kim

DOI:10.15681/KSWE.2018.34.6.569 Vol.34(No.6) 569-578, 2018

To minimize the negative alterations in hydrologic and water quality environment in urban areas due to urbanization, Low Impact Development (LID) techniques are actively applied. In Korea, LID facilities are classified as Non-point Pollution Reduction Facilities (NPRFs), and therefore they are evaluated using the performance evaluation method for NPRFs. However, while LID facilities are generally installed in small, distributed configuration and mainly work with the infiltration process, the existing NPRFs are installed on a large scale and mainly work with the reservoir process. Therefore, some limitations are expected in assessing both facilities using the same method as they differ in properties. To solve these problems, in this study, a new method for performance evaluation was proposed with focus on bio-retention LID facilities. EPA SWMM was used to reproduce the hydrologic and water quality phenomena in study area, and SWMM-LID module used to simulate TP interception performance by installing a bio-retention cell under various conditions through long-term simulations. Finally, an empirical formula for Load Capture Ratio (LCR) was derived based on storm water interception ratio in the same form as the existing method. Using the existing formula in estimating the LCR is likely to overestimate the performance of interception for non-point pollutants in the extremely low design capacity, and also underestimate it in the moderate and high design capacity.

Bio-retention, EPA SWMM, LID, Load Capture Ratio

김성진 Sung-jin Kim , 정세웅 Se-woong Chung , 박형석 Hyungseok Park , 오정국 Jungkuk Oh , 박대연 Daeyeon Park

DOI:10.15681/KSWE.2018.34.6.579 Vol.34(No.6) 579-590, 2018

The lakes’ metabolism bears important information for the assessment of the carbon budget due to the accumulation or loss of carbon in the lake as well as the dynamics of the food webs through primary production. A lake-scale metabolism is evaluated by Gross Primary Production (GPP), Ecosystem Respiration (R), and Net Ecosystem Production (NEP), which is the difference between the first two values. Methods for estimating GPP and R are based on the levels carbon and oxygen. Estimation of carbon is expensive because of the use of radioactive materials which requires a high degree of proficiency. The purpose of this study was to estimate Lake Daecheong ecosystem metabolism using high frequency water temperature data and DO measurement sensor, widely utilized in the field of water quality monitoring, and to evaluate the possibility of using the application method. High frequency data was collected at intervals of 10 minutes from September to December 2017 by installing a thermistor chain and a DO sensor in downstream of Daechung Dam. The data was then used to estimate GPP, R and NEP using the R public program LakeMetabolizer, and other metabolism models (mle, ols, kalman, bookkeep). Calculations of gas exchange coefficient methods (cole, crusius, heiskanen, macIntyre, read, soloviev, vachon) were compared. According to the result, Lake Daecheong has some deviation based on the application method, but it was generally estimated that the NEP value is negative and acts as a source of atmospheric carbon in a heterotrophic system. Although the high frequency sensor data used in this study had negative and positive GPP and R values during the physical mixing process, they can be used to monitor real-time metabolic changes in the ecosystem if these problems are solved.

Ecosystem metabolism, Gross primary production, Lake Metabolizer, Net primary production, Respiration

박윤경 Yoonkyung Park , 이재관 Jae Kwan Lee , 김정숙 Jeongsook Kim , 김상단 Sangdan Kim

DOI:10.15681/KSWE.2018.34.6.591 Vol.34(No.6) 591-601, 2018

Optimized BMP plans for controlling water quality using the Pareto trade-off surface curve in upper basin of Namgang Dam is proposed. The proposed alternatives consist of BMP installation scenarios in which the reduction efficiency of non-point pollutants is maximized in a given budget. The multi-objective optimization process for determining the optimal alternatives was performed without direct implementation of a watershed model such as SWAT analysis, thereby reducing the time taken. The shortening of the calculation time further enhances the applicability of the multi-objective optimization technique in preparing regional water quality management alternatives. In this study, different types of BMP are applied depending on the land use conditions. Fertilizer input control and vegetative filter strip are considered as alternatives to applying BMP to the field but only control of fertilizer input can be applied to rice paddies. Fertilizer input control and vegetative filter strip can be installed separately or simultaneously in a hydrologic response unit. Finally, 175 BMP application alternatives were developed for the water quality management of the upper river basin of Namgang dam. The proposed application alternative can be displayed on the map, which has the advantage of clearly defining the BMP installation location.

BMP, Multi-objective optimization, SWAT, Water quality management

민정기 Jeong-ki Min , 김동희 Dong-hee Kim , 문정숙 Jeong-suk Moon , 김진영 Jin-young Kim , 공동수 Dongsoo Kong

DOI:10.15681/KSWE.2018.34.6.602 Vol.34(No.6) 602-620, 2018

Korean benthic macroinvertebrate community from 959 sites and 14 environmental factors that could affect the biological distribution were surveyed and analyzed. The 438 taxa were divided into six groups according to TWINSPAN. Based on the environmental factor values corresponding to each taxon, the average and range of environmental factors for each biological group tended to increase or decrease in eight environmental factors (altitude, slope, current velocity, fraction of fine particles in substrates, turbidity, BOD5, T-N and T-P). As a result of discriminant analysis (hit ratio: 69.6 %), environmental factors that significantly influence the distribution of each biological group were BOD5, altitude, catchment area, T-N, T-P and fraction of fine particles in substrates. The discriminant functions 1 and 2 classified the existing six biological groups (clustered by TWINSPAN) into five (group 1: highland highly sensitive group; group 2: lowland sensitive group, group; 3 and 4: lowland slightly tolerant group; group 5: lowland tolerant group; group 6: lowland highly tolerant group). Most of the benthic macroinvertebrates were identified in the species level. However, a few others were identified in genus or family level, too. Even the organisms belonging to the same genus or family may prefer different environmental factors in the species level, the identification of characteristic of the habitat environment preferred by organism and species level identification of these organisms are utmost. The results of this study may be used as basic information on environmental factors which can be considered in preservation and restoration research for biodiversity.

Benthic macroinvertebrates, Benthic macroinvertebrate types, Discriminant analysis, Environmental factors, TWINSPAN

정상조 Sangjo Jeong

DOI:10.15681/KSWE.2018.34.6.621 Vol.34(No.6) 621-631, 2018

In this study, catalyst was made through incipient wetness method using palladium (Pd) as noble metal, indium (In) as secondary metal, and montmorillonite (MK10) and Al pillared montmorillonite (Al-MK10) as supporters. The nitrate reduction rate of the catalysts was measured by batch experiments where H2 gas was used as reducing agent and formic acid as pH controller. Transmission electron microscopy (TEM) equipped with energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were all used to determine the elemental distribution of Pd, In, Al, and Si on catalysts. It was observed that Al pillaring increased the Al/Si elemental composition ratio and point of zero charge of MK10, but decreased its BET specific surface area and pore volume. The nitrate reduction rate of Al-MK10 Pd/In was 2.0 ~ 2.5 times higher than that of MK10 Pd/In using artificial groundwater (GW) in ambient temperature and pressure. Nitrate reduction rates in GW were 1.2 ~ 1.7 times lower than those in distilled deionized water (DDW). Nitrate reduction rates in acidic conditions were higher than those in neutral condition in both GW and DDW. The amount of produced NH3-N over degraded NO3- at acid conditions was lower than that of neutral condition. Even though the leaching of Pd after reaction was measured in DDW it was not detected when both Al-MK10 Pd/In and MK10 Pd/In were used in GW. The modification of montmorillonite as a supporter significantly increased the reductive catalytic activities of nitrates. However, the ratio of producing ammonia by-products to degraded nitrates in ambient temperature and pressure was similar.

Catalyst, Indium, Nitrate, Palladium, Reduction

강미리 Mi-ri Kang , 민중혁 Joong-hyuk Min , 최정규 Jungkyu Choi , 박수영 Suyoung Park , 신창민 Changmin Shin , 공동수 Dongsoo Kong , 김한순 Han Soon Kim

DOI:10.15681/KSWE.2018.34.6.632 Vol.34(No.6) 632-641, 2018

Algal dynamics is controlled by multiple environmental factors such as flow dynamics, water temperature, trophic level, and irradiance. Underwater irradiance penetrating from the atmosphere is exponentially decreased in water column due to absorption and scattering by water molecule and suspended particles including phytoplankton. As the exponential decrease in underwater irradiance affects algal photosynthesis, regulating their spatial distribution, it is critical to understand the light extinction characteristics to find out the mechanisms of algal dynamics more systematically. Despite the significance, the recent data have been rarely reported in the main stream areas of large rivers, Korea. In this study, the euphotic depths and light extinction coefficients were determined by monitoring the vertical variation of underwater irradiance and water quality in the main channel of Nakdong River near Dodong Seowon once a week during summer of 2016. The average values of euphotic depth and light extinction coefficient were 4.0 m and 1.3 m^-1, respectively. The degree of light extinction increased in turbid water due to flooding, causing an approximate 50 % decrease in euphotic depth. Also, the impact was greater than the self-shading effect during the periods of cyanobacterial bloom. The individual light extinction coefficients for background, total suspended solid and algal levels, frequently used in surface water quality modeling, were determined as 0.305 m^-1, 0.090 m^-1/mg·L^-1, 0.013 m^-1/μg·L^-1, respectively. The values estimated in this study were within or close to the ranges reported in literatures.

Euphotic Depth, Light Extinction, Nakdong River, Underwater Irradiance, Water Quality Modeling

서지은 Jieun Seoa , 손영규 Younggyu Sonb

DOI:10.15681/KSWE.2018.34.6.642 Vol.34(No.6) 642-649, 2018

The effect of gas sparging on sonochemical oxidation was investigated in a 300 kHz sonoreactor under various liquid height/volume conditions (5 ~ 30λ, 3.4 ~ 9.0 L), determined by the wavelength of the applied frequency. The electrical input power was maintained constant for all cases < repetition of input >. Sonochemical activity drastically decreased from 15λ and the liquid height of 10λ was suggested as the optimal height for 300 kHz without gas sparging. In our previous research, the sonochemical activity observed was five-times higher when air sparging was applied for 36 kHz. On the other hand, no enhancement was obtained at 10, 15, 25 and 30λ using air sparging (1, 3, and 6 L/min) for 300 kHz in this study 2 = 80 % : 20 % (DO saturation≈100 %) was suggested as an optimal gas sparging condition.

Cavitation, DO concentration, Gas sparging, Sonochemical oxidation, Sonochemistry

김호섭 Ho-sub Kim , 김상용 Sang-yong Kim , 박윤희 Yun-hee Park

DOI:10.15681/KSWE.2018.34.6.650 Vol.34(No.6) 650-660, 2018

The objective of this study was to compare the rainfall-runoff characteristics in streams of classified urban and rural watershed using land use and population density. EMC (event mean concentration) of BOD, COD, TP and SS increased significantly in urban and rural watershed, but that of TN remained unchanged. Although there were no significant differences in EMC of BOD, COD, TN, TP depending on the watershed characteristics, EMC of BOD and COD significantly increased in the urban watershed, while EMC of TP increased in the rural watershed. In the urban watershed, the first flush time was faster and the first flush effect was stronger in BOD, COD, and TP. However, the difference between cumulative mass and cumulative volume was found to be less than 0.2 in the rural watershed, indicating a weak first flush effect. The discharged masses of BOD (70 %), COD (64 %), and TP (66 %) in the first flush of runoff were higher in urban watershed, while TN (67 %) was higher in rural watershed. The reproducibility of first flush time and the strength of first flush using CV (coefficient of variation) was found to be more reproducible for first flush time in both watersheds. In rural watershed, the CV value of first flush time for TP out of water quality parameters was lower. Whereas the CV values of first flush time for BOD, COD and TP in urban watersheds were similar.

EMC, First flush effect, Runoff, Rural watershed, Urban watershed

류희성 Hui-seong Ryu , 신라영 Ra-young Shin , 서경애 Kyung-ae Seo , 이정호 Jung-ho Lee , 김경현 Kyunghyun Kim

DOI:10.15681/KSWE.2018.34.6.661 Vol.34(No.6) 661-668, 2018

Geosmin is volatile metabolites produced by a range of filamentous cyanobacteria which causes taste and odor problems in drinking water. Molecular ecological methods which target biosynthetic genes (geoA) are widely adopted to detect geosmin-producing cyanobacteria. The aim of this study was to investigate the potential production capability of 8 strains isolated from the Nakdong River. Ultimately, a suggestion for a genetical monitoring tool for the identification of geosmin producers in domestic waters was to be made. Geosmin was detected using solid phase microextraction gas chromatography mass spectrometry (SPME GC-MS) in two strains of Dolichospermum plactonicum (DGUC006, DGUC012) that were cultured for 28 day. The highest concentrations during the experiment period was 17,535 ngL^-1 and 14,311 ngL^-1 respectively. Additionally, geoA genes were amplified using two primers (geo78F/971R and geo78F/982R) from strains shown to produce geosmin, while amplification products were not detected in any of non-producing strains. PCR product (766 bp) was slightly shorter than the expected size for geosmin producers. According to the BLAST analysis, amplified genes were at nucleotide level with Anabaena ucrainica (HQ404996, HQ404997), Dolichospermum planctonicum (KM13400) and Dolichospermum ucrainicum (MF996872) between 99 ~ 100 %. Both strains were thus confirmed as potential geosmin-producing species. We concluded that the molecular method of analysis was a useful tool for monitoring potential cyanobacterial producers of geosmin.

Dolichospermum, Nakdong River, Odorous metabolites, Off-flavor, Pseudanabaena

백종석 Baek Jongseok , 김형산 Kim Hyungsan , 신현석 Shin Hyunsuk , 김재문 Kim Jaemoon , 박경재 Park Kyungjae

DOI:10.15681/KSWE.2018.34.6.669 Vol.34(No.6) 669-677, 2018

Torrential rain and drought are repeated due to the increase in the unpredictable fluctuating of rainfall patterns. It is time for stabilize water resource management in terms of disaster prevention. Distributed control from sources is needed to minimize damages caused by torrential rains and droughts. Rain barrel can be used to reduce the runoff as they collect and store rainwater. In response to this situation, Seoul Metropolitan Government and other local governments implemented a project to support the installation of rain barrel and provided 90% of the cost of installing it in private areas. However, with limited budget, it is difficult to distribute rainwater to the city which is mostly covered by private areas. In this study, Samho-dong, Ulsan, where pilot projects of water cycle leading city are underway, analyzed the effects of reducing the runoff with respect to the amount of rainwater that can be used, and analyzed the economics of recoverable investment cost when installed. From the analysis, it was established that it is possible to show sufficient efficiency with a small capacity without the need to install large rain barrel effectively in the private sector, and to support the installation cost of less than 70 percent of the rainwater can be recovered.

Detached residential complex, EPA SWMM, Rain barrel, Rainwater reuse, Storage

김연태 Youn-tae Kim , 정의진 Euijin Chung , 박종훈 Jonghoon Park , 우남칠 Nam C. Woo

DOI:10.15681/KSWE.2018.34.6.678 Vol.34(No.6) 678-687, 2018

The purpose of this study was to understand the unique and complicated feature of urban stream receiving various inflows. The Yangjae stream, the second tier of the Han River, runs through the southern parts of Seoul, Korea and its middle part flows on the boundary of Seoul where land use is actively changing. Stream flow was greatly influenced by rainfall. Other than rainfall events, effluent discharge from wastewater treatment plant (WWTP) comprised 51 % of stream flux. As a result, majority ions water chemistry was changed at the receiving zone of the discharged effluent (Zone A). Its contribution increased to 69.9 % at the second sampling period with low stream flow. In the middle zone, inflows from the northern area, recently developed to a residential district showed low NO₃-N and high HCO₃, Ca, SO₄, and SiO₂ indicating the effects of groundwater and concrete. One inflow (T-8), with extremely high Na and Cl, median SiO₂, was assessed to have anthropogenic influence, however its contribution to main stream was under 1 %. Road construction near Y-13 also affected water chemistry leading to the highest Na and Cl concentration. These hydro chemical changes can be critically used to evaluate the changes in water budget and fate of chemicals in a peri-urban watershed occasioned by human activities on the Yangjae.

Discharge, Seoul, Urban stream, Water chemistry

유순주 Soonju Yu , 이은정 Eunjeong Lee , 박민지 Minji Park , 김갑순 Kapsoon Kim , 임종권 Jongkwon Im , 류인구 Ingu Ryu , 최황정 Hwangjeong Choi , 변명섭 Myeongseop Byeon , 노혜란 Hyeran Noh

DOI:10.15681/KSWE.2018.34.6.688 Vol.34(No.6) 688-702, 2018

Since the 1970s regulations against the pollution of drinking water have been introduced in Lake Paldang watershed area. To understand the effects of water environment management policies and the impacts of climate changes on Lake Paldang, a long-term comprehensive study of this watershed and the changes in its water environment is required. In this study, we analyzed changes in the weather, hydrology, sources of pollution, water quality, and algal development from 2000 to 2015 year based on the statistical data provided by several national information systems. While the population and amount of sewage in the Lake Paldang watershed increased by about 1.5 times, the amount of animal manure showed a decreasing trend during the same period. The wastewater also increased by about 1.5 times while the amount of water intakes rose by about 1.14 times. The water quality in front of the Paldang Dam, which is the representative monitoring site of the Lake Paldang, was stable. The annual average BOD concentration remained within 2 mg/L, which is a “Good (lb)” level according to the environment standards of Republic of Korea. The development of phytoplankton and harmful cyanobacteria were largely influenced by meteorological factors.

Algae, Paldang Watershed, Water Pollutant load, Water Quality