• 제목/요약/키워드: COD

검색결과 3,261건 처리시간 0.032초

진해만에 있어서의 COD의 시공간적인 특성 및 결정인자 (The Determining factors and Temporal and Spatial Characteristics of Chemical Oxygen Demand in Jinhae Bay)

  • 김종구;조은일
    • 한국환경과학회지
    • /
    • 제8권2호
    • /
    • pp.189-195
    • /
    • 1999
  • Determining factors and temporal & spatial characteristics of COD(Chemical Oxygen Demand) at the sea surface in Jinhae bay have been examined by using seasonal data, taken at twenty six stations over the whole bay during 1989~1994 by NERDA. The data have been analyzed in terms of long term means, anomalously large values. Jinhae bay is divided into three regions based on the time mean : mouth of Jinhae bay, inner sea of Masan bay, western sea of Jinhae bay called region 1,2 and 3, respectively. The horizontal distribution of the long term mean of COD at each station is similar to those of nitrogen and phosphorus. Characteristics of whole mean variation in the year shows high range of variation in region 2. It was appear to decreases every year in whole trend. Factors determining seasonal variation in whole COD mean are relative to salinity and nutrient, affected by precipitation in summer. Spatial variation shows high range of fluctuation in region 2 compare to other region. Factors determining of spatial variation of COD was appear to nutrient, affected by pollutant load of land area and bottom sediment. The long term mean of COD at each station is closely related with thats of nutrients. The correlation coefficient between COD and nitrogen, phosphate phosphorus was found to be high as 0.75, 0.78, respectively. Anomalously large COD was observed 14 times at 6 stations. These stations are located in inner sea of Masan bay(Region 2) and Songjeong bay(Region 1). The seasonal frequency of the observed anomalous COD is large in April, and other seasons are much the same.

  • PDF

생태계 모델을 이용한 진해만의 COD의 거동과 분포특성 평가 (Estimation of a Transport and Distribution of COD using Eco-hydrodynamic Model in Jinhae Bay)

  • 홍석진;이원찬;정래홍;박성은;장주형;김형철;김동명
    • 한국환경과학회지
    • /
    • 제16권12호
    • /
    • pp.1369-1382
    • /
    • 2007
  • To find proper water quality management strategy for oxygen consumption organic matters in Jinhae bay, the physical process and net supply/decomposition in terms of COD was estimated by three-dimensional eco-hydrodynamic modeling. The estimation results of physical process in terms of COD showed that transportation of COD was dominant in loading area from land to sea, while accumulation of COD was dominant in $middle{\sim}bottom$ level. In case of surface level, the net supply rate of COD was $0{\sim}60\;mg/m^2/day$. The net decomposition rate of COD was $0{\sim}-0.05\;mg/m^2/day$($-5{\sim}-10$ m, in depth) to 2 level, and $-0.05{\sim}-0.20\;mg/m^2/day(10m{\sim})$ to bottom level. These results indicate that the biological decomposition and physical accumulation of COD are occurred for the most part of Jinhae Bay bottom. The variation of net supply or net decomposition rate of COD as reducing land based input loading is also remarkable. Therefore, it is important to consider both allochthonous and autochthonous oxygen demanding organic matters to improve the water quality of Jinhae Bay.

영농기간동안 논 유출수 BOD, COD 자료를 이용한 TOC 농도 추정 (Estimation of TOC Concentration using BOD, COD in Runoff from Paddy Fields)

  • 최동호;정재운;윤광식;이경숙;최우정;임상선;박하나;임병진;황태희
    • 한국물환경학회지
    • /
    • 제28권6호
    • /
    • pp.813-818
    • /
    • 2012
  • BOD and COD are currently used for water quality indices, but adoption of TOC for TMDL (Total Maximum Daily Load) is being suggested. Estimation of TOC using existing BOD and COD data is very important to diagnosis water quality trend when TOC is used for water quality index of organic matter in the future. The relationships between BOD COD and TOC in runoff from paddy fields were investigated during 2008-2011. The observed mean concentration of EMCs (Event Mean Concentration) for BOD, COD, TOC were 3.87, 10.97, 7.26 mg/L respectively. The correlation coefficients between BOD-TOC and COD-TOC were 0.42, 0.73, respectively. The coefficient of determination of regression equation for BOD-TOC and COD-TOC were 0.18, 0.53 respectively. Even though, conversion of COD data to TOC seems to be rather reliable than that of BOD-TOC, further monitoring is recommended to ensure better interpretation of relationship among BOD, COD and TOC.

COD(Crack Opening Displacement) 측정에 의한 강재표면의 피로균열진전속도 평가 (Evaluation of Fatigue Crack Growth Rate on the Surface of Steel Members Using COD(Crack Opening Displacement) Measurement)

  • 김광진;김인태
    • 한국구조물진단유지관리공학회 논문집
    • /
    • 제15권2호
    • /
    • pp.179-188
    • /
    • 2011
  • 강부재의 피로가 주요원인이 되어 구조물이 붕괴되거나 교체되는 사례를 찾아보기 어렵다. 이처럼 사실상 피로에 대해서는 손상을 허용하고 있지만, 발견되는 피로균열에 대한 직접적인 상태평가는 이루어지지 않고 있다. 피로균열에 대한 진전 비진전성의 판단 및 균열진전속도의 평가가 이루어져야만, 합리적인 보수 보강 공법의 선정과 시행시기가 결정될 수 있을 것이다. 본 연구에서는 측정되는 COD(Crack Opening Displacement)를 통한 피로균열진전속도 평가법을 검토하기 위하여, 2종류의 관통 균열 시험편과 면외거셋 용접이음 시험편의 균열진전시험을 실시하였다. 그리고 실용적인 COD의 측정을 위해 변형률 게이지를 이용하는 방법에 대해 검토하였다. 그 결과, COD 측정을 통한 균열진전속도의 합리적인 평가법을 제안하였고, 변형률 게이지를 이용한 성공적인 COD 측정을 실험적으로 증명하였다.

우리나라 연안에 서식하는 대구(Gadus macrocephalus)의 위 내용물 비교 (Comparison of Stomach Contents of Pacific Cod (Gadus macrocephalus) in Korean Coastal Waters)

  • 박충열;곽우석
    • 한국어류학회지
    • /
    • 제21권1호
    • /
    • pp.28-37
    • /
    • 2009
  • 본 연구는 위 내용물 분석에 의하여 우리나라 동해, 서해, 진해만에 서식하는 대구의 먹이에 관하여 조사하였다. 분석한 대구 시료는 총 518개체였으며, 체장 범위는 15.5~77.0 cm 였다. 동해안 대구의 주요 먹이 조성은 새우류, 두족류, 어류였다. 서해안 대구의 주요 먹이 조성은 두족류를 제외한 나머지 항목에서 동해안 대구와 유사하였다. 반면에 진해만 대구는 다른 두 해역과 달리 어류를 주로 섭식하는 것으로 나타났다. 작은 크기의 대구는 다양한 먹이를 섭식 하지만 성장하면서 새우류와 어류를 주로 섭식하는 것으로 나타났다. 따라서 특정 크기에 있어서 대구의 먹이는 서식지의 먹이 풍부도와 그 크기에 많은 영향을 받는다. 진해만 대구의 높은 공위율은 성숙한 대구가 산란기 동안에 일시적으로 섭식을 중지하는 것과 관계있는 것으로 보인다.

세계 대구산업의 공급사슬 구조 분석 - 코로나19와 한국 중계무역을 중심으로 - (A Study on Supply Chain Analysis of Global Cod Industry - Focusing on COVID-19 pandemic and Intermediary Trade of South Korea -)

  • 황산산;이정필
    • 수산경영론집
    • /
    • 제53권3호
    • /
    • pp.1-15
    • /
    • 2022
  • The global cod market is supposed to have weak structure with a high dependence on the supply of Russia, the United States, Norway, and China. The COVID-19 pandemic has significantly disrupted the cod supply chain for the worse. Fish processing facilities in China stopped their operation, and cod demand declined due to shrinking consumption in Europe. The position of South Korea as an intermediary trade country between Russia and China strengthened due to the U.S.-China trade war and the Atlantic cod decrease in 2019. However, this global cod supply chain collapse has caused South Korea to export accumulated cod to Indonesia and Vietnam at a bargain price, showing that South Korea was unable to cope with this supply chain crisis. The primary purpose of this study is to investigate changes in the global cod supply chain and their impacts on the intermediary trade of South Korea caused by the COVID-19 pandemic. It also aims to provide implications by analyzing advanced cases in Denmark. As the cod supply chain crisis countermeasures, this study suggests that South Korea develop high value-added marine products, gain competitive advantages by solidifying the value chains of related countries, and activate export by discovering alternative markets in terms of the supply chain of the cod industry.

COD 분석시 염소이온의 간섭작용에 관한 연구 (A Suitable Dichromate Reflux Method for the Analysis of Chlorous Wastewater)

  • 김종규;김남천;민달기
    • 한국환경보건학회지
    • /
    • 제15권2호
    • /
    • pp.33-40
    • /
    • 1989
  • Dichromate reflux method for COD analysis is one of the useful and precise way to solve the organic content of the wastewater. But the standard procedure for COD is not entirely satisfactory for sample containing appreciable amounts of inhibiting substance, especially chloride ion. Under the conditions of the established test, a big disadvantage of the method is that dichromate oxidizes chloride quantitatively to chlorine. When it is necessary to use silver sulfate as a catalyst in the COD procedure, chloride must be removed before the addition of the catalyst. Silver sulfate and mecuric sulfate forms a precipitate of AgCl and HgCl$_{2}$ separately which is not completely oxidized during the test and, therefore, cannot be corrected for. So, we evaluate and compensate the amount of chloride oxidation in the absence of chemicals during the experimental procedure. Calculation of COD is made using the following reviced formula: real COD = tested COD - 0.2277Cl.

  • PDF

생물막 반응조에서 돈사폐수의 유기물 특성 및 동력학계수 산정 (Organic Characteristic of Piggery Wastewater and Kinetic Estimation in Biofilm Reactor)

  • 임재명;한동준;권재혁
    • 산업기술연구
    • /
    • 제16권
    • /
    • pp.51-60
    • /
    • 1996
  • This research was performed for the fundamental data using a advanced treatment process of piggery wastewater. Characteristics of influent wastewater was divided with various methods in fixed biofilm batch reasctor. Fractons of organic were divided into readily biodegradable soluble COD(Ss), slowly biodegradable COD(Xs), nonbiodegradable soluble COD($S_I$), and nonbiodegradable suspended COD($X_I$). Experimental results were summerized as following : i) biodegradable organics fraction in piggery wastewater was about 88.1 percent, and fraction of readily biodegradable soluble COD was about 66.1 percent. ii) Fractions of nonbiodegradable soluble COD was 11~12 percent, and soluble inert COD by metabolism was producted about 6~8 percent. iii) Active biomass fraction of attached biofilm was about 54.7 percent, and substrate utilization rate and maximum specific growth rate of heterotrophs were $8.315d^{-1}$ and $3.823d^{-1}$, respectively.

  • PDF

외해 가두리 대구 양식업 경제적 타당성 분석 (Analysis of Economical Validity about Offshore Cage Culture for Cod)

  • 이광남
    • 수산해양교육연구
    • /
    • 제28권6호
    • /
    • pp.1724-1738
    • /
    • 2016
  • This paper was researched on economic feasibility and sensibility of operation to offshore cage culture for cod. Offshore cage culture for cod needs to invest high budget what to construction and operation. And it was required variety methods about analysis of economic feasibility. Therefore, these were studied NPV, B/C and sensitivity for each by assuming a six scenarios considering the product performance according to the size of cod and culturing methods of fingerlings, etc. As a results, even though economy, if efficiency is low, it is a priority need the technical development to promote the feed efficiency to increase economic feasibility and should make efforts to enhance the business economy to strengthen the price competitiveness pricing with high quality products through quality control and brand recognition of cod. It expects to be used as a reference for related research in the future by deriving policy implications based on the method of analysis of the economic feasibility on offshore cage culture for cod.

양돈폐수 처리를 위한 혐기성 생물반응기의 성능 비교 (Performance Evaluation of Anaerobic Bioreactors in Treating Swine Wastewater)

  • 김종수;이국희;사동민
    • 대한환경공학회지
    • /
    • 제22권11호
    • /
    • pp.2047-2058
    • /
    • 2000
  • 양돈폐수의 효율적인 혐기성 처리를 위하여 실험실 규모 UASB, AF, 그리고 이단 ASBF 생물반응기를 구성하고 HRT 1일과 OLR $5.1kg-COD/m^3{\cdot}d$까지 200일간 연속운전하고 운전인자가 공정에 미치는 영향과 처리효율을 비교하였다. 양돈폐수는 유기물, 고형물, 그리고 암모니아를 고농도로 함유하고 있으며 축사의 형태와 계절의 변화에 큰 영향을 받는다. 하수종말처리장 혐기성 소화조 잉여 슬러지에 의한 혐기성 생물반응기의 식종은 효과적이었으며 적응기간은 약 40일 정도 소요되었으나 media로 충전된 필터형 생물반응기인 AF와 이단 ASBF의 적응 속도가 UASB보다 빨랐다. 유입수 T-N 370~800mg/L에서 생물반응기는 77~91% 의 높고 안정된 COD 제거율을 보였으나 유입수 T-N 760~1,310 mg/L에서 COD 제거율은 24~94%로 불안정하였으며 전반적으로 감소되었다. 양돈폐수에 함유된 암모니아는 메탄균에 대한 저해작용을 나타낼 수 있는 충분한 농도이므로 효율적인 혐기성 소화처리를 위하여 전처리로서 암모니아의 제거는 필수적이다. 생물반응기는 $1.1{\sim}2.2kg-COD/m^3{\cdot}d$의 비교적 낮은 OLR에서 COD 제거효율은 78.9~81.5%, 그리고 biogas 발생량은 $0.39{\sim}0.59m^3/kg-COD_r$로 효과적이었으나 유입수 COD의 증가 혹은 HRT 단축운전에 의한 OLR의 증가에 따라 COD 제거효율은 감소하였으며 UASB는 AF와 이단 ASBF보다 COD 제거효율 감소폭이 컸다. AF와 이단 ASBF는 충전된 media와 이단화에 의하여 biomass의 보유능력이 우수하며 높은 OLR에도 안정적이며 높은 COD 제거율올 나타내므로 고농도의 유기물을 함유하며 축사의 형태와 계절에 따라 특성의 변화가 큰 양돈폐수의 처리에 효율적이다.

  • PDF