장주형 Ju Hyoung Jang , 정재훈 Jae Hun Jong , 문현생 Hyun Saing Mun , 김경현 Kyung Hyun Kim , 서일원 Il Won Seo

DOI:10.15681/KSWE.2016.32.3.243 Vol.32(No.3) 243-252, 2016

In cases of water pollution accidents, accurate prediction for arrival time and concentration of contaminants in a river is essential to take proper measures and minimize their impact on downstream water intake facilities. It is critical to fully understand the behavior characteristics of contaminants on river surface, especially in case of oil spill accidents. Therefore, in this study, the effects of main parameters of advection and diffusion of contaminants were analyzed and validated by comparing the results of Lagrangian particle tracking (LPT) simulation of Environmental Fluid Dynamic Code (EFDC) model with those of Global Position System (GPS)-equipped drifter experiment. Prevention scenario modeling was accomplished by taking cases of movable weir operation into account. The simulated water level and flow velocity fluctuations agreed well with observations. There was no significant difference in the speed of surface particle movement between 5 and 10 layer modeling. Therefore, 5 layer modeling could be chosen to reduce computational time. It was found that full three dimensional modeling simulated wind effects on surface particle movements more sensitively than depth-averaged two dimensional modeling. The diffusion range of particles was linearly proportional to horizontal diffusivity by sensitivity analysis. Horizontal diffusivity estimated from the results of GPS-equipped drifter experiment was 0.096 m2/sec, which was considered to be valid for applying the LPT module in this area. Finally, the scenario analysis results showed that particle movements could be stagnant when discharge from the upstream weir was reduced, implying the possibility of securing time for mitigation actions such as oil boom installation and wiping oil contaminants. The outcomes of this study can help improve the prediction accuracy of particle tracking simulation to establish the most suitable mitigation plan considering the combination of movable weir operation.

GPS-equipped drifter, Lagrangian particle tracking, Mitigation plan, Oil spill, Sensitive analysis

정용준 Yong-jun Jung , 김예진 Ye-jin Kim

DOI:10.15681/KSWE.2016.32.3.253 Vol.32(No.3) 253-260, 2016

To reduce energy consumption in wastewater treatment plants (WWTPs), renewable energy applications such as small hydropower, solar energy, and wind energy are popular. However, it should be noticed that energy originated from operation of wastewater treatment process can be reduced through optimized operation based on analysis of factors affecting energy. In this research, the relationship to the various operational variables and influent factors was explored using correlation analysis and decision tree algorithm. Due to the non-linear characteristics of the process, it was difficult to find clear linear patterns through correlation analysis. However, decision tree algorithm showed its usefulness in uncovering hidden patterns that consume energy. As operational factors, influent flowrate, the amount of aeration, nitrate recycling pumping rate, and sludge wasting pumping rate were selected as important factors. For environmental factors associated with influent compositions and removal rate, BOD and T-N removal rate were selected as significant factors.

Correlation analysis, Decision tree algorithm, Energy consumption, Wastewater treatment plant

김용진 Yong-jin Kim , 백준수 Jun-soo Baek , 윤석제 Seok-jea Youn , 김헌년 Hun-nyun Kim , 이병천 Byoung-cheun Lee , 김귀다 Guee Da Kim , 박송은 Song Eun Park , 유경아 Kyung A You , 이재관 Jae-kwan Lee

DOI:10.15681/KSWE.2016.32.3.261 Vol.32(No.3) 261-270, 2016

We analyzed cyanobacterial community including akinete, resting cell, and benthic cyanobacteria in sediment of Bukhan, Namhan-River, Paldang-Lake, and Kyeongan-Stream and compared the physicochemical factors for water and pore water. We also performed cyanobacteria growth potential test through incubating sediment. As a result of physicochemical analysis, the concentrations of nutrients were similar for each depth of Bukhan-River. For Namhan-River and Lake Paldang sites, the concentrations of TP and DTN in bottom and deep water had higher levels. DTN in water body composed of NO3-N(73%) while DTN in pore water composed of NH3-N(77.8%). Benthic cyanobacteria in the sediment such as Oscillatoria tenuis, O. limosa, Phormidium tenue, Pseudanabaena limnetica, and Lyngbya sp. were dominant (between 0.0~243.3×103 cells/g, w/w). Cell densities of cyanobacteria in sediment depth of 0~2 cm in most sites were higher compared to those in other depths. The cell density of cyanobacteria in sediment correlated with pH, conductivity, BOD5, TP, DTP, and chl. a. Increased phytoplankton and organic matters were found to be able to inhibit the growth of benthic cyanobacteria. Results of cyanobacteria growth potential test after incubating sediment revealed that harmful cyanobacteria (Anabaena, Aphanizomenon, Microcystis, and Oscillatoria) appeared at 7 days post culturing. Base on these results, the methods used in this study are considered to be able to determine the appearance of harmful cyanobacteria.

Akinete, Benthic Cyanobacteria, Paldang, Sediment

이혜진 Hae-jin Lee , 박혜경 Hae-kyung Park , 이재학 Jae Hak Lee , 박아름 A Reum Park , 천세억 Se-uk Cheon

DOI:10.15681/KSWE.2016.32.3.271 Vol.32(No.3) 271-280, 2016

The aim of this study was to analyze spatial and temporal patterns of bacterial pollution levels and the relationship between bacterial pollutants and environmental parameters at the main stream and tributaries of Nakdong River. Water quality data including total coliform and fecal coliform were compiled from a total of 50 monitoring sites (30 at the main stream and 20 at the tributaries) along with rainfall and discharge data for three consecutive years from 2012 to 2014. During the study periods, the geometric mean values of total coliforms and fecal coliforms in the main stream were 74 (22~465) CFU/100 mL and 8 (3~42) CFU/100 mL, respectively. The geometric mean values of total coliforms and fecal coliforms in the tributaries were 275 (36~5,145) CFU/100 mL and 6 (1~1,352) CFU/100 mL, respectively. High concentrations of fecal coliforms were observed at Gumi (M 10), Hyeonpung (M 19), Hapcheon (M 23), and Namji (M 25) in the main stream, whereas Gamcheon (T 6), Bakcheon (T 7), Geumho-gang (T 8), and Gyeseongcheon (T 16) were identified as pollution hot spots in the tributaries. Although bacterial pollution levels showed complex behavior across monitoring sites and time, the highest coliform concentrations were routinely observed in the monsoon season between July and September of each year, indicating that the pollution levels were strongly dependent on precipitation in addition to other physiochemical parameters. Statistically significant correlations were found between fecal coliform concentrations and precipitation (r=0.403, p<0.01), followed by SS (r=0.425, p<0.01), nutrient TP (r=0.388, p<0.01), organic matter COD (r=0.322, p<0.01), and PO4-P (r=0.317, p<0.01) in the main stream in the order of correlation coefficient from high to low.

Coliform pollution, Environmental factors, Nakdong River, Precipitation

이용석 Yong-seok Lee , 전만식 Man-sig Jun , 김문숙 Moon-sook Kim

DOI:10.15681/KSWE.2016.32.3.281 Vol.32(No.3) 281-290, 2016

In the northernmost basin of the Bukhan River, pollution sources can have a concentrated distribution. In these basins, small streams show low flow with various and rapid water quality change in low pollutants load. Therefore, a water quality improvement plan of small streams and main stem will be necessary to establish the characteristics of small streams. This study selected a representative Hwacheon-gun in the northernmost basin of the Bukhan River. Hydro analysis was performed with GIS tools using DEM. A total of 152 small streams were listed. A total of 51 survey locations were selected after applying the selection criteria. Flow rate and water qualities were investigated. Pollution sources and pollutants loads were calculated for each basin. Pollution grade and typological classification were performed by cluster analysis using standardized environmental condition factors. As a result, G04, G01, H01 locations were found to have the worst pollution grades whereas J01, P01, and P02 had less pollution. Typological analyses were able to classify six types for the surveyed small streams. An effective water quality improvement plan was obtained based on the results of pollution grade and typological analysis using environmental condition factors of this study.

Environmental condition, Pollution grade, Small stream, Typology, Water quality

이기봉 Gi-bong Lee , 김현주 Hyeon-joo Kim , 박수경 Soo-gyeong Park , 옥용식 Yong-sik Ok , 안종화 Johng-hwa Ahn

DOI:10.15681/KSWE.2016.32.3.291 Vol.32(No.3) 291-296, 2016

This study investigated the potential use of soybean stover (SS) (0.1-0.5 g/100 mL)and rice hull (RH) (1.5-3.5 g/100 mL) derived biochars for removing methylene blue (100 mg/L) from wastewater compared to activated carbon (AC) (0.1-0.5 g/100 mL). The adsorption equilibrium data were best represented by Langmuir adsorption isotherm. The calculated maximum adsorption capacity was 71.42 mg/g for AC, 30.30 mg/g for SS, and 4.76 mg/g for RH. The adsorption kinetics was found to follow the pseudo-second order kinetics model. The rate constant was 0.0020-0.0065 g/mg.min for AC, 0.0069-0.5787 g/mg.min for SS, and 0.1370-0.3060 for RH. AC and SS biochars showed considerable potential for adsorption.

Activated carbon, Adsorption, Adsorption isotherm, Biochar, Kinetics, Methylene blue

전동걸 Dong Jie Tian , 이범 Beom Lee , 박준규 Jun Gye Park , 전항배 Hang Bae Jun

DOI:10.15681/KSWE.2016.32.3.297 Vol.32(No.3) 297-302, 2016

Microbial electrochemical technology (MET) has recently been studied to improve the efficiency of a traditional anaerobic digestion (AD). The purpose of this study was to investigate the impact of MET in the system when MET was combined with traditional AD (i.e., AD-MET). Electrodes used in the MET were Cu coated graphite electrodes. They were supplied with a voltage of 0.3 V. AD started to generate methane in 80 days. But AD-MET started to generate methane from the initial operation after the system started. It was observed that AD-MET reached steady state faster and produced higher methane yield than AD. During the steady state, the average daily methane productions in AD and AD-MET were 2.3L/d and 4.9L/d, respectively. Methane yields were 0.07-CH4/gㆍCODre in AD and 0.25L-CH4/gㆍCODre in AD-MET. In AD-MET, the production rates of total volatile fatty acids (TVFAs) and soluble chemical oxygen demand (SCOD) were 0.12 mg TVFAs/mg VSㆍd and 0.35 mg SCOD/mg VSㆍd, respectively. They were significantly (p < 0.05) higher than those in AD. However, the concentrations of residual TVFAs in both systems were not significantly (p > 0.05) different from each other, confirming that methane conversion in AD-MET was greater than that in AD.

Alkalinity, Anaerobic digestion, Biogas, Methane, Microbial electrochemical technology

엄한기 Han Ki Eom , 최유현 Yoo Hyun Choi , 주현종 Hyun Jong Joo

DOI:10.15681/KSWE.2016.32.3.303 Vol.32(No.3) 303-309, 2016

This study aimed to assay the biological removal of TDS (total dissolved solids) from RO (reverse osmosis) rejected water. Following bio-sorption of TDS with AGS (aerobic granular sludge), the effects of TDS on biological nitrogen removal were examined. The bio-sorption of TDS after AGS treatment was confirmed by checking for TDS removal efficiency and surface analysis of microorganisms with SEM and EDS. Then, the effects of TDS on biological nitrogen removal and the denitrification efficiency were evaluated using the MBR reactor. According to the results, the bio-sorption of TDS with AGS was 0.1 mg TDS/mg AGS, and we confirmed that the microorganism surfaces had adsorbed the TDS. Biological nitrogen removal efficiency was measured at inhibiting denitrification at 4,000 mg/L of TDS-injected material. Based on this study, it is necessary to pretreat TDS-containing RO rejected water and to maintain TDS concentration lower than a specific value (≤4,000 mg/L), when considering biological nitrogen removal.

Aerobic Granular Sludge, Bio-sorption, Nitrogen, RO rejected water, TDS

전환돈 Hwan Don Jun , 이지호 Ji Ho Lee , 김수전 Soo Jun Kim

DOI:10.15681/KSWE.2016.32.3.310 Vol.32(No.3) 310-317, 2016

It has been a big problem to estimate rainfall for the studies of mud-debris flows because the estimated rainfall from the nearest AWS (Automatic Weather Station) can tend to be quite inaccurate at individual sites. This study attempts to improve this problem through accurate rainfall depth estimation by applying an artificial neural network with radar rainfall data. For this, three models were made according to utilizing methodologies of rainfall data. The first model uses the nearest rainfall, observing the site from an ungauged site. The second uses only radar rainfall data and the third model integrates the above two models using both radar and observed rainfall at the sites around the ungauged site. This methodology was applied to the metropolitan area in Korea. It appeared as though the third model improved rainfall estimations by the largest margin. Therefore, the proposed methodology can be applied to forecast mud-debris flows in ungageed sites.

Artificial neural network, Automatic weather station, Mud-debris flow, Radar rainfall

박재홍 Jae Hong Park , 김용석 Yong Seok Kim , 이원석 Won Seok Lee

DOI:10.15681/KSWE.2016.32.3.318 Vol.32(No.3) 318-324, 2016

The significance of an integrated environmental management system implementation can be summarized into three sections. The first is that the paradigm of a permit system will be changed from the existing media-specific permits to cross-media permits. In the near future, the cross-media license will be granted based on the diagnostic results of the plant. The second is that it will be established through a social concensus, i.e., consultations with stakeholders and direct participation in the system design process of stakeholders. The third is that it will have flexibility in its operating system. In the near future, it will be possible to management an environment through its industrial workplace itself and determine if emission standards are being complied with or not through statistical methods. In addition there is also an urgent need for complementary parts in order to enhance the driving force of the integrated environmental management system which is based on transparency, reliability and flexibility. In other words, it is necessary to continuously promote in order to diffuse consensus and increase an understanding of implementation through an integrated environmental management system. It is also necessary to establish a new organization and educate authorized representatives so that they have the tools to smoothly perform the system.

BAT-AEL, Integrated environment management system, Paradigm shift, Social concensus