송영채 Young Chae Song , 오경근 Gyung Geun Oh

DOI:10.15681/KSWE.2015.31.4.351 Vol.31(No.4) 351-359, 2015

The study on the improvement of discharge water quality from domestic wastewater treatment plant (DWTP) was performed in a filter type bioelectrochemical system. The COD removal efficiency for a synthetic discharge water was about 88%, and the effluent COD was less than 5mg/L. The nitrification efficiency of the bioelectrochemical system was over 97%, but a considerable amount of the nitrogen was remained as nitrate form in the effluent. The total nitrogen removal efficiency was only around 30%. There are no significant differences in the removal of COD and nitrogen at 0.6 and 0.8V of the applied voltages between anode and cathode. The removal of COD and nitrogen in the system were quite stable when the HRT ranged from 60 to 15 minutes, and at 10 minutes of HRT, the nitrification efficiency was slightly decreased. The performance of the bioelectrochemical system has quickly recovered from the shocks in the influent due to high concentration of COD and nitrogen. For the effluent that discharged from the DWTP, the removal efficiencies of COD and total nitrogen from the bioelectrochemical system were 50 and 30%, respectively. Thus the bioelectrochemical system was a feasible process for further polishing the effluent quality from DWTP.

bioelectrochemical, domestic wastewater, effluent water quality, improvement

구혜민 Hye Min Koo , 이용호 Yong Ho Lee , 박대원 Dae Won Pak

DOI:10.15681/KSWE.2015.31.4.360 Vol.31(No.4) 360-366, 2015

In this study TiO2 nanotube was grown on Ti by anodic oxidation to be used as a photocatalyst. The growth and formation of TiO2 nanotube was monitored during anodization in ethylene glycol electrolyte by changing voltage and composition of electrolyte. Commercially available titanium plate (purity>99.8%, thickness:1mm) Applied voltage and concentration of NH4F and H2O were varied to find the optimum condition. Applied voltage is important to make TiO2 nanotube and the electrolyte containing ethylene glycol, 0.2 wt% NH4F and 2 vol% H2O was confirmed to be the optimum conditions for the formation and growth of TiO2 nanotubes.

Anodizing, Current density, Photocatalyst, TiO2 nanotube

정세웅 Se Woong Chung , S Geoffrey Schladow

DOI:10.15681/KSWE.2015.31.4.367 Vol.31(No.4) 367-376, 2015

The momentum and kinetic turbulent energy carried by the wind to a stratified lake lead to basin-scale motions, which provide a major driving force for vertical and horizontal mixing. A three-dimensional (3D) hydrodynamic model was applied to Lake Tahoe, located between California and Nevada, USA, to simulate the dominant basin-scale internal waves in the deep lake. The results demonstrated that the model well represents the temporal and vertical variations of water temperature that allows the internal waves to be energized correctly at the basin scale. Both the model and thermistor chain (TC) data identified the presence of Kelvin modes and Poincare mode internal waves. The lake was weakly stratified during the study period, and produced large amplitude (up to 60 m) of internal oscillations after several wind events and partial upwelling near the southwestern lake. The partial upwelling and followed coastal jets could be an important feature of basin-scale internal waves because they can cause re-suspension and horizontal transport of fine particles from nearshore to offshore. The internal wave dynamics can be also associated with the distributions of water quality variables such as dissolved oxygen and nutrients in the lake. Thus, the basin-scale internal waves and horizontal circulation processes need to be accurately modeled for the correct simulation of the dissolved and particulate contaminants, and biogeochemical processes in the lake.

Internal wave, Lake Tahoe, Stratified lake, Upwelling and downwelling

한송희 Song Hee Han , 김요용 Yo Yong Kim , 성연국 Yeon Gook Sung , 박익범 Ik Beom Park , 조덕희 Deok Hee Cho , 남우경 Woo Kyung Nam , 김창규 Chang Gyu Kim , 오조교 Jo Kyo Oh

DOI:10.15681/KSWE.2015.31.4.377 Vol.31(No.4) 377-386, 2015

The purpose of this research was to suggest the water quality improvement in streams by evaluating the distribution characteristics of organics and ammonia nitrogen discharged by pollution sources from human living. The public sewage treatment plants’(PSTPs) effluents and the waters from streams in Gyeonggi-do were sampled and analyzed. Nitrogenous oxygen demand (NOD) was measured for the stream waters as well as the PSTPs effluents, and the correlations of NOD and NH3-N, NH3-N and water temperature in the PSTPs effluents were confirmed. In the case of the stream waters, the ratios of NOD to BOD and NH3-N increased in the downstream sites after discharging the PSTPs effluents. As a result of statistical analysis of NH3-N concentrations for the national water quality monitoring streams in Gyeonggi-do, NH3-N showed the non-normal distribution which were biased to the left, but showed the considerable level because of higher coefficient of variation. Therefore, it is required to establish the water quality standard for the NH3-N as a new parameter for judging the quality of the streams. In addition, inducing complete nitrification and introducing a logical standard setting system are needed to improve the water quality of streams by identifying distribution of the nitrogen components from PSTPs effluents.

Ammonia nitrogen, NOD, nitrogenous oxygen demand, PSTPs, public sewage treatment plants, Streams

김용범 Yong Beon Kim , 안종화 Johng Hwa Ahn

DOI:10.15681/KSWE.2015.31.4.387 Vol.31(No.4) 387-391, 2015

This study was performed to evaluate the effect of pH (8-12) and molar ratio of magnesium and phosphate ([Mg2+]/[PO43-]) (0.6-1.4) on struvite crystallization of anaerobic digester supernatant using seawater as magnesium source. pH range of 9-10 is favorable for ammonium and phosphate recoveries. The recovery efficiency of ammonium was highest at [Mg2+]/[PO43-] of 1.0 and pH 10. On the other hand, high phosphate recovery efficiency (> 99%) was achieved at ([Mg2+]/[PO43-]) of 1.4 and pH 10. The results demonstrated that seawater can be considered as low-cost magnesium source to recover phosphorus from anaerobic digester supernatant.

Anaerobic digester supernatant, Nitrogen recovery, Phosphorus recovery, Seawater, Struvite crystallization

최희정 Hee Jeong Choi

DOI:10.15681/KSWE.2015.31.4.392 Vol.31(No.4) 392-398, 2015

The aim of this study was to investigate the bio-adsorption using modified zeolite with Mg (Mg-zeolite) in the dyeing wastewater treatment. Mg-zeolite adsorbed successfully 100% of the color, suspended solid (SS). chemical oxygen demand (COD), biological oxygen demand (BOD), total nitrogen (TN) and total phosphorus (TP) in the dyeing wastewater at the following optimal Mg-zeolite loading: 20 mg/L for colour, SS, TN and TP, 30 mg/L for BOD and COD. These results indicated that the amount of 1 mg/L Mg-zeolite adsorbed 11.6 mg/L for color, 9.5 mg/L for SS, 45.0 mg/L for COD, 12.7 mg/L for BOD, 0.91 mg/L for TP and 2.25 mg/L for TN. The bio-adsorbent, Mg-zeolite, can be a promising adsorption due to its high efficiency and low dose requirements.

Adsorption, Dyeing Wastewater, Modified Zeolite, Wastewater Treatment, Zeolite

안조환 Jo Hwan Ahn

DOI:10.15681/KSWE.2015.31.4.399 Vol.31(No.4) 399-406, 2015

A sequencing batch reactor was operated under different pH conditions to see the influence of free ammonia (FA) and free nitrous acid (FNA) to microbial community on ammonium partial nitrification. Long-term influences of FA and FNA were evaluated by polymerase chain reaction-denaturing gradient gel electrophoresis and fluorescence in situ hybridization. Nitrite accumulation was successfully achieved at pH 8.2 and 6.3. The shifts in the microbial community were observed when influent ammonia concentration increased to 1 g NH4-N/L at pH 8.2, and then when pH was dropped to 6.3. Both Nitrosomonas and Nitrosospira were selected during the startup of the reactor, and eventually became dominant members as ammonia-oxidizing bacteria. The results of molecular microbiological analysis strongly suggested that the composition of microbial community was changed according to the method used to control nitrite-oxidizing bacteria.

Ammonia-oxidizing bacteria, Fluorescence in situ hybridization, Free ammonia, Free nitrous acid, Nitrite- oxidizing bacteria, Polymerase chain reaction-denaturing gradient gel electrophoresis

손광익 Kwang Ik Son , 김형준 Hyung Joon Kim , 임경재 Kyoung Jae Lim , 정영훈 Young Hun Jung

DOI:10.15681/KSWE.2015.31.4.407 Vol.31(No.4) 407-417, 2015

Soil loss is one of the significant disasters which have threatened human community and ecosystem. Particularly, Korea has high vulnerability of soil loss because rainfall is concentrated during summer and mountainous regions take more than 70% of total land resources. Accordingly, the sediment control management plan are required to prevent the loss of soil resources and to improve water quality in the receiving waterbodies. In this regard, the objectives of this study are 1) to quantify the effect of the Vegetative Filter Strip (VFS) on sediment runoff reduction and 2) to analyze the relationship of rainfall intensity and sediment runoff. For this, SATEEC and VFSMOD were used to estimate sediment runoff according to rainfall intensity and to quantify the effect of VFS on sediment runoff reduction, respectively. In this study, the VFS has higher impact on sediment reduction for lower maximum rainfall intensity, which means that the maximum rainfall intensity is one of significant factors to control sediment runoff. Also, the sediment with VFS considered was highly correlated with maximum rainfall intensity. For these results, this study will contribute to extend the applicability of VFS in establishing eco-friendly sediment control plans.

SATEEC, Sediment, Soil loss, VFSMOD-w, VFS

임봉수 Bong Su Lim , 경해룡 Hai Long Jing

DOI:10.15681/KSWE.2015.31.4.418 Vol.31(No.4) 418-427, 2015

This study was carried out to evaluate the performance of a lab-scale novel septic tank system for improving the conventional septic tank in the developing countries of water shortages. The lab-scale novel septic tank system consists of sepetic tank, aeration tank with HBC-ring, and sand filter. Optimum HRT was reguired about 1.5days to get a total COD removal efficiency of 90%, COD, BOD and SS removal efficiency was about 70%, 60%, and 85% in sepetic tank only. The structure of sepetic tank with two stages results in the high removal efficiency of organic matter. When sepetic tank, aeration tank, and sand filter were more than HRT 1.5days, 18hrs, and 12hrs, respectively, final effluent was less than 20 mg/L of BOD, 14 mg/L of SS, so that there is a high potential of its use for reusing water in flush toilet. There is no significant effect of HRT change on nutrient removal. Total nitrogen removal efficiency was about 40%, final effluent was 30~40 mg/L of TN, total phosphorus removal efficiency was about 11~25%, final effluent was 9~12 mg/L of TP. Because there is very small amounts of organic nitrogen and phosphorus in effluent, it was possible to reuse water for agricultural use.

Developing Countries of Water Shortages, Optimum HRT, Reusing Water in Flush Toilet, Septic Tank System

임봉수 Bong Su Lim , 박윤해 Youn Hae Park , 김태응 Tae Eung Kim

DOI:10.15681/KSWE.2015.31.4.428 Vol.31(No.4) 428-435, 2015

This study was carried out to evaluate the performance of a inflow controller for the control of combined sewer overflows (CSOs). Because of the inflow controller could be adjusted manually by predicting the maximum amount of peak flow, the mechanical adjustment of this controller was higher than the existing fixed-type controller in field application. Standardizing the relationship between the flow and the clearance and angle of an inlet cover plate on the inflow conditions can selected to the optimum conditions for the on-site. It was concluded that BOD pollutant loading at the region in which inflow controller was installed had shown the removal efficiency rate of 42%.

Combined Sewer Overflows, CSOs, Inflow Controller, Inlet Cover Plate, Peak Flow