• 상하수도학회지
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• 제13권1호
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• pp.51-60
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• 1999

An intermittently-aerated, intermittently-decanted single-reactor process (KIDEA process : KIST intermittently decanted extended aeration process) was applied for nitrogen removal from wastewater. Synthetic wastewater with chemical oxygen demand (COD): nitrogen (N) ratio of approximately 5.25: 1 was used. The average COD removal efficiency reached above 95%, and under optimal conditions nitrogen removal efficiency also reached above 90%. This process consisted of 72 minute aeration, 48 minute settling and 24 minute effluent decanting with continuous feeding of influent wastewater from the bottom of the reactor, and did not require a separate anoxic mixing-phase. In this process, nitritation ($1^{st}$ step of nitrification) was induced but nitratation($2^{nd}$ step of nitrification) was suppressed. Main factors responsible for the accumulation of nitrite ion in the experimental condition were free ammonium and dissolved oxygen. This condition of nitrite build-up accelerated by continuous feed flow in the bottom of the KIDEA reactor because of high concentration of ammonia nitrogen in the influent. This research provides one of answers to control nitrate build-up.

• 한국물환경학회지
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• 제26권6호
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• pp.969-975
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• 2010

Estimating the organic matter loadings from individual treated sewage has become important for establishment of effective management strategies to control refractory organic matter (R-OM) in watersheds. For this study, regression equations were constructed using treated sewage data to convert the chemical oxygen demand (COD) concentrations, which are mostly available from open database, into total organic carbon (TOC) and R-OM concentrations. Effluent samples were collected from five major sewage treatment plants (STPs) located upstream of the lake Paldang. Variations in the OM concentrations were not associated with either the location of the STP or the sampling season. The effluent investigated were characterized by higher ratio of R-OM with respect to biodegradable organic matter (B-OM) and higher presence of dissolved organic matters (DOM) versus particulate organic matter (POM). Compared to $COD_{Mn}$, $COD_{Cr}$ exhibited higher oxidation efficiencies and greater variations in the concentrations. The concentrations of $COD_{Mn}$ were positively correlated with dissolved organic carbon (DOC), total organic carbon (TOC), and R-OM concentrations. There was nearly no seasonal and annual variation in the regression equations between $COD_{Mn}$ and TOC or R-OM concentrations. The constructed regression equations for TOC and R-OM were $0.650({\pm}0.071){\times}COD_{Mn}+1.426({\pm}0.575)$ and $0.340({\pm}0.083){\times}COD_{Mn}+2.054({\pm}0.670)$, respectively. The established equations are expected to contribute to estimating OM loadings from the STPs into the lake Paldang and also to compensating for the deficiency of the data for effluent OM concentrations in STP.

• 한국습지학회지
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• 제16권1호
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• pp.153-160
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• 2014

호소의 유기물질 오염도를 정확하게 파악하고, 호소내 수질관리를 개선하기위해 총유기탄소(TOC) 환경기준이 설정되었다. 낙동강수계에 위치하고 있는 상수원수로 이용되는 4개 호소의 화학적산소요구량(COD)과 TOC의 상관성은 $R^2$=0.639로 매우 유의한 결과로 나타났다. 농업용수 2개 호소와 늪 1개소의 자료를 모두 이용한 COD와 TOC의 상관성은 $R^2$=0.774로 더 높아졌으나 이것은 검출된 농도범위의 증가에 의한 것으로 보인다. TOC에 의해 요구되는 COD의 수준에 관계없이 탄소산화율은 평균 62%에 해당하였으며, 호소에 따른 현저한 차이는 보이지 않았다($62{\pm}8%$). 이것은 연구대상으로 한 호소의 유기물질 성상이 유사함을 나타낸다. TOC 자료가 충분히 구축될 때까지 COD 자료를 현명하게 활용하여야 하고, 이를 위해서는 호소에 영향을 미치는 유역의 특성과 호소의 이용측면을 고려하여 호소의 유기물질 수준을 평가할 필요가 있다.

• 한국축산시설환경학회지
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• 제1권2호
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• pp.165-171
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• 1995

액상 폐기물의 자원화 처리 방법의 하나로서 공해방지와 지력증강을 위하여 액상유우 분뇨의 호기성 처리기술을 실용화하는데 기초자료가 되는 액상유우 분뇨의 화학적 특성 분석 결과는 다음과 같다. 1)고액 분리하지 않은 액상유우 분뇨의 고형물 농도(TS)는 7.54(%wb), 산도(pH)는 6.92, 유기물 농도(TS)는 79.34(%TS), 화학적 산소 요구량(COD)은 81,300~96,500(mg/$\ell$), 암모니아태 질소(NH$_3$-N)는 1,690~2,300(mgfe), 및 질산태 질소(NO,-Pf)는 36.0-40.0(mg/$\ell$) 이었다. 2) 고액분리된 액상유우 분뇨의 화학적 특성은 우사형식, 분뇨배출방식, 고액분리기 종류 등에 따라 상이하며 고형물 농도는 4.43~7.95(%wb), 산도(pH)는 7.31, 유기물 농도(VS)는 74.57~79.93(%TS), 화학적 산소 요구량(COD)은 52,400~73,700(mg/$\ell$), 암모니아태 질소(NH$_3$-N)는 2,035~2,960(mg/$\ell$), 질산태 질소(NO$_3$-N)는 19.0~30.0(mg/$\ell$) 의 범위를 나타내고 있었다.

• 한국환경과학회지
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• 제9권5호
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• pp.429-436
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• 2000

In order to study on the variational characteristics of water quality and chlorolphyll a concentration the water samples were collected daily or three times a week during the period from April 1990 to November 1991 at Kukdong port located in the northern Kamak bay of Southern Korea I made an analysis on biological factor as chlorophyll a concentration as well as physico-chemical factors such as water temperature salinity sigma-t dissolved oxygen, nutrients (ammonia, nitrite, nitrate, phosphate, and silicate) N/P ratio and chemical oxygen demand. In Northern Kamak bay seasonal variations in physical factors such as water temperature salinity and sigma-t were very marked. On the other hand chemical factors such as nutrients concentration and COD were not so. Chemical factors, in particular silicate were influenced by input of freshwater. And the roles of silicate on the seasonal succession of phytoplankton species composition was very low. Phytoplankton biomass as measured by chlorophyll a concentration was very high all the year round and it was controlled by the combination of several factors especially of N/P ratio determined by dissolved inorganic nitrogen.

• Journal of Electrochemical Science and Technology
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• 제12권1호
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• pp.82-91
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• 2021

This study was conducted to investigate the effect of initial pH, current density, and electrolysis time on process performance in terms of decolorization and chemical oxygen demand (COD) removal from disperse dyebath wastewater (DDW) by mono-polar parallel laboratory scale electrocoagulation (EC) process. COD reduction of 51.3% and decolorization of 92.8% were obtained with operating cost of 0.19 €/㎥ treated wastewater for Al-Al electrode pair, while 90.5% of decolorization and 49.2% of COD reduction were obtained with operating cost of 0.20 €/㎥ treated wastewater for an Fe-Fe electrode pair. The amount of sludge production were highly related to type of the electrode materials. At the optimum conditions, the amount of sludge produced were 0.18 kg/㎥ and 0.28 kg/㎥ for Al-Al and Fe-Fe electrode pairs, respectively. High decolorization can be explained by the hydrophobic nature of the disperse dye, while limited COD removal was observed due to the high dissolved organic matter of the DDW based on auxiliary chemicals. Energy, electrode, and chemical consumptions and sludge handling were considered as major cost items to find a cost-effective and sustainable solution for EC. The contribution of each cost items on operating cost were determined as 10.0%, 51.1%, 30.5% and 8.4% for Al-Al, and they were also determined as 9.0%, 38.0%, 40.5% and 12.5% for Fe-Fe, respectively. COD reduction and decolorization were fitted to first-order kinetic rule.

• 한국해양환경ㆍ에너지학회지
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• 제18권2호
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• pp.74-80
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• 2015

통영 연안 양식장 주변 해역에서의 환경특성을 조사하기 위해 2013년 7월부터 12월까지 통영 주변 10개 정점에서 해수와 퇴적물 내의 pH, 용존산소(DO), 용존무기질소(DIN), 용존무기인(DIP), 화학적산소요구량(COD), 산휘발성물질(AVS)에 대해 분석하였다. 양식장 주변 해수의 수질항목들은 계절별에 따른 경향성을 나타내었으며, 퇴적물 속 COD와 AVS를 분석한 결과 수질항목과는 달리 어장으로부터의 거리에 따라 농도가 감소하는 경향을 나타내었다. 이는 본 조사지역에서 반폐쇄성 만에 위치하고 있는 어장 활동에 의해 오염된 유기퇴적물이 비교적 빠른 유속으로 인해 주변 해역으로 분산된 것으로 예측된다.

• 한국지반환경공학회 논문집
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• 제10권1호
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• pp.43-48
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• 2009

본 연구에서는 소규모 처리공법으로서 질소와 인을 효율적으로 제거할 수 있으며, 관리 및 운전이 용이한 연속회분식반응조(SBR)공정의 영양염류 제거특성에 대하여 연구하였다. 특히, 질소의 탈질 및 인의 과잉섭취에 영향을 미치는, 무산소구간의 반복횟수에 따라 변화하는 용존산소, COD, 질소 및 인의 반응특성을 파악하여 SBR공정의 무산소-호기 구간반복에 따른 운전특성을 파악하고자 하였다. 이에 호기-무산소구간을 1~4회 반복하여 Run 1~4의 실험을 수행한 결과, 무산소구간의 반복횟수가 많아질수록 탈질을 위한 낮은 용존산소 유지가 어려운 것으로 나타났다. COD 제거율의 경우 운전에 상관없이 모두 91% 이상의 양호한 결과를 나타냈으나, 추가적인 무산소구간이 없을 때 효율이 약간 더 우수하였다. 질소제거에 있어서는 무산소구간이 2회 및 3회 반복되었을 때 약 68%의 높은 제거율을 나타냈으며, 배출되는 질소의 구성은 99% 이상이 $NOX^--N$ 이었다. 인 제거에 있어서는 무산소구간이 1회~3회 반복되었을 때 약 40%의 양호한 제거효율을 나타냈다.

• 대한화학회지
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• 제14권3호
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• pp.243-256
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• 1970

Halogen contents of the river water of Seoul city and of municipal reservoirs were investigated from June in 1969 to February in 1970. Bromine contents were ranging from 0.006 to 0.048 mg/1 of the reservoirs, 0.021 to 0.048 mg/1 of Han River, 0.051 to 0.540 mg/1 of rivers running through residential areas and 0.083 to 0.920 mg/1 of rivers running through industrial areas. Bromine contents increased as the river water became contaminated. Most of Br/Cl of Han River and the reservoirs were higher than $3.4{\times}10^{-3}$ of sea water. Bromine contents at 17 different places were the largest in November. The contents of chlorine, iodine and COD (chemical oxygen demand) were nearly correlated with that of bromine. Bromine contents of the river waters in Seoul chiefly originated from consumption of domestic and industrial salt.

• 한국농공학회논문집
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• 제58권2호
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• pp.1-9
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• 2016

This study aims to assess the effectiveness of activated carbon (AC) and crushed concrete (CC) as capping material to block the release of nitrogen, phosphorus, and organic substance from reservoir sediments. The efficiency of AC and CC as capping material was evaluated in a reactor in which a 1 or 3 cm thick layer of capping materials was placed on the sediments collected from Mansu reservoir in Anseong-city. Dissolved oxygen (DO) concentration, total nitrogen (T-N), total phosphorus (T-P), and chemical oxygen demand (COD) concentration in reservoir water above the uncapped sediments and capping material were monitored for 45 days. The release rate of T-N was in the following increasing order: AC 3 cm ($1.18mg/m^2{\cdot}d$) < CC 1 cm ($2.66mg/m^2{\cdot}d$) < AC 1 cm ($2.94mg/m^2{\cdot}d$) < CC 3 cm ($3.42mg/m^2{\cdot}d$) < uncapped ($4.59mg/m^2{\cdot}d$). The release rate of T-P was in the following increasing order: AC 3 cm ($0mg/m^2{\cdot}d$) $${\approx_-}$$ CC 3 cm ($0mg/m^2{\cdot}d$) < CC 1 cm ($0.03mg/m^2{\cdot}d$) < AC 1 cm capped ($0.07mg/m^2{\cdot}d$) < uncapped ($0.24mg/m^2{\cdot}d$). The release of nitrogen and phosphorus were effectively blocked by AC capping of 3 cm thickness, and CC capping of 3 cm thickness effectively controlled the release of phosphorus. The order of increasing COD release rate was as follows: AC 3 cm ($0mg/m^2{\cdot}d$) $${\approx_-}$$ CC 3 cm ($0mg/m^2{\cdot}d$) < CC 1 cm ($5.03mg/m^2{\cdot}d$) < AC 1 cm ($7.28mg/m^2{\cdot}d$) < uncapped ($10.05mg/m^2{\cdot}d$), indicating that AC and CC capping effectively interrupted the release of organic contaminants from the sediments. It was concluded that AC and CC could effectively block the release of T-N, T-P and COD release from contaminated reservoir sediments.