김지원 Ji Won Kim , 이혜원 Hye Won Lee , 이용석 Yong Seok Lee , 최정현 Jung Hyun Choi

DOI:10.15681/KSWE.2020.36.2.89 JKWST Vol.36(No.2) 89-97, 2020

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North Han River is a very unique type of water system, where Hwacheon, Chuncheon, Soyanggang, Euiam and Cheongpyeong Dams are located consecutively. These dams are operated differently in the amount of discharge and release schedule according to their structure and purpose of use. They have different water quality characteristics depending on external pollutant inflow and internal mixing condition. Therefore, this study investigated the relationship between the upper dam and down stream river with respect to water quality indicators, such as water temperature, electrical conductivity, BOD, COD, TN and TP of the North Han River. The similarities and correlations representing the relationship were analyzed by Pearson’s correlation r and t-test. The data was taken from the Ministry of Environment’s water quality monitoring from 1999 to 2018. The results show that water temperature and electrical conductivity of the dam and river are similar and correlated. However, it turned out that there was no similarities and correlations in BOD, COD, TN and TP that are significantly affected by subaqueous reaction mechanism. The results of this study present the impact of the dam on the water quality of North Han River, which can be used as useful data for management of water quality.

조현경 Hyun Kyung Cho , 김상민 Sang Min Kim

DOI:10.15681/KSWE.2020.36.2.98 JKWST Vol.36(No.2) 98-108, 2020

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The purpose of this study was to evaluate water quality in Hapcheon dam via using the Hydrological Simulation Program-Fortran (HSPF) model and applied livestock reduction scenarios. Hapcheon dam watershed input data for the HSPF model were established using the stream, land use, digital elevation map and meteorological data and others. The HSPF model was calibrated and validated using the observed water quality data from 2000 to 2016. For water quality simulation, we calculated the generated and discharge loads of the population, livestock, industry and land use following the guideline provided by the Ministry of Environment. The pollutant data were obtained from National Institute of Environmental Research (NIER). The monthly discharge load were estimated by applying the delivery rate. The calibration and validation results showed that the annual mean BOD had a difference of 0.22 mg/L and an error of ±13 %, T-N had a difference of 0.66 mg/L and an error of ±16 % and T-P had a difference of 0.027 mg/L and an error of ±13 %. In order to evaluate the nonpoint pollutants management effects, we applied livestock reduction scenarios because livestock consists of the largest portion of pollutants. As a result of the 20 % of livestock reduction, BOD, T-N and T-P decreased by 3 %, 1 % and 3 %, respectively. When 40 % of livestock reduction was applied, BOD, T-N and T-P decreased by 5 %, 3 % and 4 %, respectively. Based on the results of this study, effective pollutant management methods can be applied to improve the water quality and achieve the target water quality of Hapcheon dam watershed.

김병성 Byungsung Kim , 임석화 Seokhwa Lim , 이상진 Sangjin Lee , 백종석 Jongseok Baek , 김재문 Jaemoon Kim

DOI:10.15681/KSWE.2020.36.2.109 JKWST Vol.36(No.2) 109-115, 2020

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Recently, since impervious areas have increased due to urban development, the water cycle system of urban watersheds has been destructed. Hence, researches on LID (Low Impact Development) technique have been conducted to solve such problems environmentally. In order to verify suitability with the scale and arrangement of LID technique, the runoff reduction effect of the LID technique should be analyzed per small watershed unit. In this study, pre-post difference of the runoff by applying the LID was estimated using the rational method and rainwater treatment capacity equation. As a result, the runoff before and after the application of LID were estimated as 22,533.5 m³ and 14,992.1 m³, respectively. In addition, rainfall-runoff simulations were carried out using SWMM to evaluate the efficiency of the LID technique. The SWMM simulation results showed that the runoff before and after the application of LID were 21,174 m³ and 15,664 m³, respectively. Based on the results of the two methods, the scale and arrangement of the LID technique were revised in order to maximize the effect of the water cycle improvement. Rainfall-runoff simulations were carried out using the SWMM with the revised LID techniques. As a result, despite 34.8 % reduction of pervious pavement area, the rate of runoff reduction increased by 2.1 %. These results indicate that designing the scale and arrangement of LID technique, while considering the total amount of inflow entering into each LID techniques, is essential to effectively achieve the goals of runoff reduction in urban development.

홍정기 Jung-ki Hong , 임종권 Jong Kwon Im , 손주연 Ju Yeon Son , 노혜란 Hye-ran Noh , 유순주 Soon-ju Yu , 이보미 Bo-mi Lee

DOI:10.15681/KSWE.2020.36.2.116 JKWST Vol.36(No.2) 116-124, 2020

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This study aims to identify the characteristics of organic matter and pollutant sources using water quality and stable isotope ratios (δ¹⁵N, δ¹³C) of the two inflow tributaries (Gulpo (GP) and Anyang (AY) streams). Water samples were analyzed in June and September 2018, and the results showed that the concentrations of nutrients, such as TN and NO₃-N, were increased at GP4, which is located at the downstream of sewage treatment facilities(STFs). TOC and TN ratios showed a strong positive correlation (R² = 0.77, p<0.01) at all points except for GP4. The results of GP’s stable isotope ratio analysis do not appear to be a constant cluster compared to AY because GPs with large amounts of pollutants from the industry (metal processing companies, etc.) have less tributary, shorter waterway and significantly different external sources. This could be attributed to different sources of external inflow despite its smaller number of tributaries and shorter waterways than AY. In the first half of the year, the δ¹⁵N of GP4 was affected by discharge of STFs, while AY3 seemed to have an influence of tributary than the discharge of STFs. Consequently, using water quality, stable isotope ratio and C/N, the sources of contamination in two streams with different contaminants were identified and origin was estimated.

유재현 Jae-hyun Yu , 이한샘 Han-saem Lee , 임병란 Byung-ran Lim , 강주형 Joo-hyoung Kang , 안태웅 Tae-ung Ahn , 신현상 Hyun-sang Shin

DOI:10.15681/KSWE.2020.36.2.125 JKWST Vol.36(No.2) 125-136, 2020

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In this study, we identified the major pollution-zones of the mainstream and its tributaries of Gongneung stream and investigated their pollution sources based on water quality, flowrate and pollution-load data of the stream having the characteristics of the urban-rural complex to examine the effect of the tributaries on the water quality changes in the mainstream. The water quality and flowrate data were collected for 10 months (2018 ~ 2019) at 3 points of mainstream and ten tributaries. Water quality index (WQI), load duration curve (LDC), discharge load density (DLD)and delivery ratios for each tributary were obtained so as to investigate the pollution characteristics and some of the information visualized on GIS. The main pollution-zone in the Gongneung stream was in the middle and lower streams, and the tributaries that may affect the pollution of the area were JS, JY, SL and SM. JS and SL had low WQI levels (34.7/37.5) and DLD (kg/d/km²) of BOD and T-P were relatively high in JY (99.2/6.00) and SL (60.0/2.07). BOD and T-P delivery ratios in JS were high (0.94/0.83), suggesting that JS had significant influence on the water quality of the main pollution-zone in the Gongneung stream. Meanwhile, SM having a high T-P delivery ratio (0.97) was found to be more affected by the non-point source due to the higher LDC excess rate (%) in the low flow compared to high flow. This study provides basic data on the water quality and pollution characteristics of the Gongneung stream, and the analysis results are expected to be used as examples for identifying the main pollution-zone and tributaries of stream and their pollution sources.

Lat Lat Tun , 정다운 Dawoon Jeong , 배효관 Hyokwan Bae

DOI:10.15681/KSWE.2020.36.2.137 JKWST Vol.36(No.2) 137-147, 2020

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A direct contact membrane distillation (DCMD) was applied to treat strong nitrogenous wastewater of anaerobic digestion supernatant (ADS) and human urine (HU). The ammonia transfer was evaluated in terms of specific ammonia transfer (SAT) value, which is the ratio of total ammoniacal nitrogen divided by the amount of water transferred. The acidification resulted in low SAT values and high quality of produced water. The ammonia transfer control in the acidic condition was stronger for HU than ADS due to higher alkalinity (pH 8.8) and ammonia concentration (5700 mg-N/L) of HU. Acidified HU at pH 4 exhibited a SAT value of 1.64 × 10^-5, which was significantly smaller than the SAT value of 3.00 × 10^-3 for the original HU. The low pH enhanced the water flux for ADS, but HU showed a steep decrease in water flux due to enhanced fouling. It was considered that the fouling intensity in acidic conditions depends on the characteristics of the wastewater source. The major foulants on the MD membrane were NaCl, CaCO₃ and CuSO₄ as recognized by the SEM-EDS. Acidified ADS and HU at pH 4 showed relatively high N content of 8.18 % and 28.03 %, respectively, as organic fouling.

강주영 Ju Yeong Kang , 조아현 Ah Hyeon Jo , 박은지 Eun Ji Park , 이한철 Han Cheol Lee , 박민지 Min Ji Park , 한진섭 Jin Sub Han , 강성규 Seong Gyu Kang , 김중범 Jung Beom Kim

DOI:10.15681/KSWE.2020.36.2.148 JKWST Vol.36(No.2) 148-152, 2020

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The quantitative accuracy of dry rehydratable film method was compared with the standard culture method to analyze the applicability of dry rehydratable film in the total aerobic bacteria test for water. The materials used in this study were 500 cases of water and were tested according to the Korean official test method for drinking water. The mean value of the total aerobic bacteria in plate count agar(PCA) and MC-Media Pad AC(MAC) were 2.6 ± 1.1 Log cfu/mL and 2.6 ± 1.2 Log cfu/mL. The p value and correlation coefficient(R²) were 0.933 and 0.9985 between the PCA and MAC, respectively, indicating no significant difference and very high correlation. According to the water types, the p value and R² were 0.887 and 0.9911 in the PCA and MAC. In the purified water, the p value was 0.973 and R² was 0.9934 in the PCA and MAC of other water. In each type of water, there were no significant differences between the PCA and MAC, and the correlation was very high. Thus, it is suggested that the MAC would be available for total aerobic bacteria test for water.

저소웅 Shaoxiong Chu , 임봉수 Bongsu Lim , 최찬수 Chansoo Choi

DOI:10.15681/KSWE.2020.36.2.153 JKWST Vol.36(No.2) 153-163, 2020

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Magnetic separation technology is an efficient and environmentally friendly technology. Compared with the traditional wastewater treatment technology, the magnetic separation technology has its unique advantages and characteristics, and has been widely applied in the field of wastewater treatment. In particular, the emergence of superconducting magnetic separation technology makes possible for high application potential and value. In this paper, which through consulting with the literatures of Korea, Chinese, United States and other countries, the magnetic separation technology applied to wastewater treatment was mainly divided into direct application of magnetic field, flocculation, adsorption, catalysis and separation coupling technology. Advantages and limitations of the magnetic separation technology in sewage treatment and its future development were also studied. Currently, magnetic separation technology needs to be studied for additional improvement in processing mechanism, design optimization of magnetic carrier and magnetic separator, and overcoming engineering application lag. The selection, optimization and manufacturing of cheap magnetic beads, highly adsorbed and easily desorbed magnetic beads, specific magnetic beads, nanocomposite magnetic beads and the research of magnetic beads recovery technology will be hot application of the magnetic separation technology based on the magnetic carriers in wastewater treatment. In order to further reduce the investment and operation costs and to promote the application of engineering, it is necessary to strengthen the research and development of high field strength using inexpensive and energy-saving magnet materials, specifically through design and development of new high efficiency magnetic separators/filters, magnetic separators and superconducting magnetic separators.