• Environmental Engineering Research
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• 제23권1호
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• pp.99-106
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• 2018

Lack of information on the Biochemical Oxygen Demand (BOD) decay rates of river water under the tropical environment has triggered this study with an aim to fill the gap. Raw sewage, treated sewage, river water and tap water were mixed in different proportions to represent river water receiving varying amounts and types of wastewater and fed in a laboratory flume in batch mode. Water samples were recirculated in the flume for 30 h and BOD and Carbonaceous BOD (CBOD) concentrations were measured at least six times. Decay rates were obtained by fitting the measured data in the first order kinetic equation. After conducting 12 experiments, the range of BOD and CBOD decay rates were found to be 0.191 to 0.92 per day and 0.107 to 0.875 per day, respectively. Median decay rates were 0.344 and 0.258 per day for BOD and CBOD, respectively, which are slightly higher than the reported values in literatures. A relationship between CBOD decay rate and BOD decay rate is proposed as $k_{CBOD}=0.8642_{k_{BOD}}-0.0349$ where, $k_{CBOD}$ is CBOD decay rate and $k_{BOD}$ is BOD decay rate. The equation can be useful to extrapolate either of the decay rates when any of the rates is unknown.

• 한국물환경학회지
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• 제28권2호
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• pp.178-184
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• 2012

BOD decay rate is a key parameter of BOD-DO models in streams and lakes. In the calibration of water quality modeling appropriate range of coefficient is required for guidance of parameter selection. In this study BOD decay rate was measured at 48 stream sites and 10 reservoir sites in 8 different river systems. The decay rate ranged from 0.09 to 0.25 $day^{-1}$ with a mean of 0.16 $day^{-1}$. Among river systems the decay rates showed significantly different ranges, with the Han River system showing higher values than other river systems. In comparing different types of water bodies, the decay rate was slightly higher in tributaries than in reservoirs and mainstreams. Our results can provide guidance to the selection of proper coefficient for various water bodies in the calibration of water quality models.

• 한국환경과학회지
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• 제17권8호
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• pp.833-840
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• 2008

Deoxygenation process in which CBOD(carbonaceous BOD) is biochemically oxidized to reduced inorganic compounds is of great significance in the oxygen demand of stream waters. The CBOD decay rate has traditionally been determined in a laboratory by CBOD bottle incubation method. But in this study, CBOD decay rates were obtained by laboratory incubation method and natural waters experiment. Average CBOD decay rate for the Nakdong river(upper zone) in natural waters were 0.553 $day^{-1}$ during April 2005 to January 2007. The values in the middle and down parts of the Nakdong river in natural waters were 0.384 $day^{-1}$ and 0.252 $day^{-1}$ at the same period of time, respectively. Average CBOD decay rates using by incubation method in the upper/middle/down parts of the main stream in the Nakdong river basin was 0.270 $day^{-1}$, and 0.289 $day^{-1}$, and 0.283 $day^{-1}$ during April 2005 to January 2007, respectively.

• 한국환경농학회지
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• 제14권1호
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• pp.7-14
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• 1995

하천 수질관리 모델인 QUAL2E를 남강에 적용한 결과는 다음과 같다. 1. 모델변수의 민감도 분석 결과는 BOD, DO의 경우 BOD decay rate constant, 영양염류인 경우 Org-N oxidation rate constant, $NH_3-N$ oxidation rate constant, Org-P decay rate constant가 각 수질인자에 중요한 변수로 작용하였다. 2. 모델보정 결과를 보면 실측치와 예측치의 상관성은 DO, BOD의 경우 r=0.93, 0.94로 높은 상관성을 보였으며 영양염류인 경우는 질산성 질소가 r=0.61이었으나, 그 외는 r=0.90 이상으로 나타났다. 3. 모델검증 결과는 보정시보다 상관성이 떨어졌으나 DO, $NO_3-N$의 경우 r=0.68, 0.45로 낮고 그 외는 r=0.75이상으로 높은 편으로 나타났다. 4. 유량과 부하량의 변화에 대하여 하류 40.5 Km 이후의 BOD 농도변화는 적었으나, 하수종말처리장 건설이후 유량과 부하량을 변화시켜 수질농도를 예측한 결과 하류 40.5 Km 이후는 함안천의 영향을 받을 것으로 예측되었다.

• 한국물환경학회지
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• 제21권5호
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• pp.511-515
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• 2005

CBOD(carbonaceous BOD) decay rate was investigated for the execution of water quality model in Nakdong-Rive basin. Estimation of laboratory-derived CBOD decay rate, $k_l$ and CBOD decay rate in natural waters, $k_d$ were carried out. Hydraulic factors were applied for the calculation of $k_d$. Values of biochemical oxygen demand were investigated in Weagwan, Koreong, Jeokpo, Namgi and Mulgeom sites for the four times. The ranges of $k_l$ value were $0.04{\pm}0.01{\sim}0.14{\pm}0.03$. The values of $k_l$ in upstream sites were much larger than those in the downstream sites. The values of $k_d$ were 0.025, 0.036, 0.005 and 0.001 at Weagwan, Jeokpo, Namgi and Mulgeom, respectively, indicating that values of $k_d$ were generally larger than those of $k_l$.

• 한국농공학회지
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• 제41권4호
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• pp.37-46
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• 1999

Field experimnet of constructed wetland for rural wastewater treatment was performed from July 1998 to April 1999 including winter to examine the seasonal effect on the wetland performance. The system worked without freezing even under $-10^{\circ}C$ of air temperature as long as watewater was flowing. BOD removal rates varied in similar pattern as the air temperature, and winter performance was relatively lower than that in the growing season. However, removing performance during winter was still significant, and BOD removal rates were almost the the same as in the growing season. SS removal rate was relativelyless affected by temmperature, but lower decay rate during the winter can result in accumulation of the SS in the system, which releases constituents in the next spring and can affect whole system performance. The winter removal rates of nutrients like T-N and T-P were decreased about half compared to the growing season and low temperature. To maintain stabilized wetland performanced including winter time, supplying minimum heating for plants could be an alternative in field application. Experimental data was compared with NADB(North Americal Wetlands for Water Quality treatment database), and general performance of the system was within the reasonable range. The pollutant loading and effluent concentration of the experimented system were in high margin. Base on the experiment and databases, the required effluent water quality could be achieved if loading rate adjusted as ilulstrated in the database.

• 상하수도학회지
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• 제14권2호
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• pp.157-163
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• 2000

An experimental study was conducted to evaluate the treatment efficiency of paper-mill wastewater using pure oxygen activated sludge process. Effects of hydraulic retention time (HRT) and organic loading on process performance and kinetics were investigated. The raw paper-mill wastewater(BOD concentration ${\leq}500mg/L$) and the effluent from dissolved air flotation(DAF) treatment(BOD concentration ${\geq}500mg/L$) were used as influent for pure oxygen activated sludge process. Average BOD removal efficiencies were above 89.3% under 6hours or longer of HRT, while under 3hours of HRT they decreased to about 82%. With the effluent from DAF process, the half saturation constants($K_S$) and the maximum specific substrate removal rate($K_{max}$) were 85 mg/L and 2.25 L/day, respectively. However, with the raw paper-mill wastewater, both $K_S$ and $K_{max}$ increased to 156 mg/L and 3.84 L/day, respectively. The microbial yield coefficient(Y) and the decay coefficient($K_d$) were 0.46 gVSS/gBOD and 0.03 L/day, respectively, with effluent from DAF process. While, Y and $K_d$ were 0.24 gVSS/gBOD and 0.035 L/day, respectively, with the raw paper-mill wastewater.

• 수산해양기술연구
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• 제17권1호
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• pp.41-47
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• 1981

The characteristics of septic tank sludges were investigated and the kinetic coefficients in the aerobic biodegradation were evaluated from bach treatability tests. Using an unbiased statistical method, the estimated values, k (substrate removal rate coefficient) =0. 0175hr-1 at 17\ulcornerC, K. (Michaelis Menten constant) = 248mg/ e, a (cell yield coefficient)=0.625, and Kd (cell decay coefficient:' =0. 00192hr-1 were obtained based on biodegradable COD(mg/ \ulcorner) and volatile suspended solids(mg/\ulcorner). The relationship between COD and BOD, COD (mg/\ulcorner) =2. 1 BOD(mg/\ulcorner) +250, also was established for the septic tank sludges. Dilution was inevitable for the grit removal because of the high viscosity of the sludges. An aerobic activated sludge process rather than anaerobic processes was recommended for the removal of soluble organics after the removal of grit and suspended solids. A multi-stage activated sludge process was adapted for this highly concentrated and not easily-degradable waste. It was estimated that a four-stage activated sludge process would require 40 hours retention time compared to 92 hours for a single-stage process, 52 hours for a double-stage process, and 46 hours for a three stage process in order to achieve an effluent quality of 84mg/ e COD( 40mg/ e BOD) with about 4, OOOmg/ \ulcorner MLSS from an influent quality of I, 500mg/ t COD(714mg/.e BOD), while multi-stages beyond four stage would not save the required retention time significantly.

• 상하수도학회지
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• 제23권6호
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• pp.743-752
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• 2009

One of the major problems associated with operation of domestic sewer lines involves hydraulic problems such as insufficient conveyance capacity, exceeding maximum velocity, and deficiency of minimum velocity. It has also been pointed out that influent concentration lower than design concentration of pollutants, which is mainly caused by unidentified inflow and infiltration, degrades the operational efficiency of many sewage treatment plants (STPs). A computer-added analysis method supporting a coupled simulation of sewage quality and quantity is essentially required to evaluate the status of existing STPs and to improve their efficiency by a proper sewer rehabilitation work. In this study, dynamic water quality simulations were conducted using MOUSE TRAP to investigate the principal parameters that governs the changes of BOD, ${NH_4}^+$, and ${PO_4}^{3-}$3- concentrations within the sewer networks based on data acquired through on-site and laboratory measurements. The BOD, ${NH_4}^+$ and ${PO_4}^{3-}$3- concentrations estimated by MOUSE TRAP was lower than theoretical pollution loads because of sedimentation and decomposition in the sewer. The results revealed that sedimentation is a most important factor than other biological reactions in decreasing pollutant load in the sewers of C-city. The sensitivity analysis of parameters pertaining to water quality changes indicated that the effect of the BOD decay rate, the initial DO concentration, the half-saturation coefficient of dissolved BOD, and the initial sediment depth is marginal. However, the influence of settling rate and temperature is relatively high because sedimentation and precipitation, rather than biological degradation, are dominant processes that affect water quality in the study sewer systems.

• 상하수도학회지
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• 제8권1호
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• pp.18-26
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• 1994

This research investigated efficient operation mode for the successful performance of SBR(sequencing batch reactor) treating fish processing wastewater, and the effect of sodium chloride (NaCl) on treatment efficiency. 2-hour-annerobic, 6-hour-aerobic and 3-hour-anoxic operation during reaction period was found an effective operating method for organic and nitrogen removal from fish processing wastewater in SBR system. The average removal efficiencies of COD, BOD, and total nitrogen in SBR operated continuousely were 91%, 95%, and 67.1%, respectively. The estimated values of biomass yield coefficient(Y), microbial decay coefficient($K_d$), and bioreaction rate constant(K) were $0.35gMLSS/gCOD_{removed}$, $0.015day^{-1}$, and $0.209hr^{-1}$, respectively. As NaCl concentration increased from 5 to 30g/L, sludge settleability was cnhanced but organic removal in the reactor was decreased. NaCl of influent had considerable relationship with COD removal, whereas it did not significant affect nitrogen removal.