• Ocean and Polar Research
• /
• 제27권1호
• /
• pp.1-13
• /
• 2005

The samples for organic carbon analysis were collected between $5^{\circ}\;and\;17^{\circ}N$ along $131.5^{\circ}W$ in the northeast Pacific KODOS (Korea Deep Ocean Study) area. The mean concentration of total organic carbon (TOC) in the surface mixed layer $({\sim}50 m)$ was $100.13{\pm}2.05{\mu}M-C$, while the mean concentration of TOC in the lower 500m of the water column was $50.19{\pm}4.23{\mu}M-C$. A strong linear regression between TOC and temperature $(r^2=0.70)$ showed that TOC distribution was controlled by physical process. Results from the linear regression between chlorophyll-a and TOC, and between chlorophyll-a and particulate organic carbon (POC), decreasing of dissolved organic carbon (DOC) in the surface layer caused by non-biological photo-oxidation process. Below the surface layer, biological production and consumption occurred. DOC accumulation dominated in the depth range of $30{\sim}50m$ and DOC consumption occurred in the depth range of $50{\sim}200m$. TOC was inversely correlated with apparent oxygen utilization (AOU) and TOC/AOU molar ratios ranged from -0.077 to -0.21. These ratios indicated that TOC oxidation was responsible fur $10.9{\sim}30.1%$ (mean 20.2%) of oxygen consumption in the NE Pacific KODOS area. In the euphotic zone, distributions of dissolved and particulate organic matter were controlled by photo-chemical, chemical, biological and physical processes.

• 상하수도학회지
• /
• 제22권1호
• /
• pp.31-38
• /
• 2008

The primary objective of this study was to evaluate the variation of the molecular size distribution by granular activated carbon (GAC) adsorption. GAC adsorption was assessed by using the rapid small-scale column test (RSSCT) and high-performance size-exclusion chromatography (HPSEC) was used to analyze the molecular size distribution (MSD) in the effluent of GAC column. RSSCT study suggested that GAC adsorption exhibited excellent interrelationship between dissolved organic carbon (DOC) breakthrough and MSD as function of bed volumes passed. After GAC treatment, the nonadsorbable fraction which was about 25percents of influent DOC corresponded to the hydrophilic (HPI) natural organic carbon (NOM) of NOM fractions and was composed entirely of <300 molecular weight (MW) in the HPSEC at the initial stage of the RSSCT operation. The dominant MW fraction in the source water was 1,000~5,000daltons. At the bed volumes 2,500, MW <500 of GAC treated water was risen rather than it of source water. After the bed volumes 7,300 of operation, the MW 1,000~3,000 fraction was closed to about 80percents of DOC found in the GAC influent. The Number-average molecular weight (Mn) value determined using HPSEC for the effluent of GAC column was gently increased as DOC breakthrough progress. The quotient p(Mw/Mn) can be used to estimate the degree of polydispersity was shown greatest value for the GAC effluent at the initial stage of the RSSCT operation.

• 한국물환경학회지
• /
• 제39권6호
• /
• pp.465-474
• /
• 2023

The chemical composition and molecular weight characteristics of dissolved organic matter (DOM) exert a profound influence on the efficiency of organic matter removal in water treatment systems, acting as efficiency predictive indicators. This research evaluated the primary chemical and molecular weight properties of DOM derived from diverse sources, including rivers, lakes, and biomasses, and assessed their relationship with the efficiency of coagulation/flocculation treatments. Dissolved organic carbon (DOC) removal efficiency through coagulation/flocculation exhibited significant correlations with DOM's hydrophobic distribution, the ratio of humic-like to protein-like fluorescence, and the molecular weight associated with humic substances (HS). These findings suggest that the DOC removal rate in coagulation/flocculation processes is enhanced by a higher presence of HS in DOM, an increased influence of externally sourced DOM, and more presence of high molecular weight compounds. The results of this study further posit that the efficacy of water treatment processes can be more accurately predicted when considering multiple DOM characteristics rather than relying on a singular trait. Based on major results from this study, a predictive model for DOC removal efficiency by coagulation/flocculation was formulated as: 24.3 - 7.83 × (fluorescence index) + 0.089 × (hydrophilic distribution) + 0.102 × (HS molecular weight). This proposed model, coupled with supplementary monitoring of influent organic matter, has the potential to enhance the design and predictive accuracy for coagulation/flocculation treatments targeting DOC removal in future applications.

• 멤브레인
• /
• 제23권6호
• /
• pp.460-468
• /
• 2013

가압식 MF공정의 전처리공정으로 침전지가 없는 혼화/응집공정에서 적정응집제 투입농도선정 및 유기물 제거성능을 평가하였다. 전처리 공정에서 생성된 플럭이 가압펌프의 임펠러에 의해 해체됨을 확인하였으며 원수탁도가 10 NTU 이하로 유입이 될 때, 혼화/응집조와 펌프후단에서 플럭형성을 위한 최적응집제 투입량은 4 mg/L (as PACl 17%)이었다. 이때의 DOC 제거율은 평균 43%이었으며, 응집제투입량을 계속적으로 증가시켜 8 mg/L (as PACl 17%)로 투입을 하였을 때, DOC 제거율은 평균 48%를 나타내어 제거율은 크게 개선되지 않았다. 전처리가 없는 PVDF 가압식 MF공정의 TMP는 0.54 bar에서 운영이 되었으며, 혼화/응집 전처리 공정을 적용하여 운영 시 TMP는 0.41 bar로 안정적인 운영이 가능하였다.

• Membrane and Water Treatment
• /
• 제15권3호
• /
• pp.99-106
• /
• 2024

This study developed an efficient management plan to improve the water quality by analyzing fluctuations in the ratio and amount of various organic substances in streams considering watershed characteristics and rainfall patterns. Monitoring was conducted on three streams and one lake over seven sessions during wet and dry seasons. Water quality indicators including total organic (TOC), refractory dissolved organic (RDOC), and particulate organic (POC) carbons were analyzed using high-temperature combustion oxidation. The three streams (Cheongmi, Yanghwa, and Bokha) displayed high TOC concentrations during the rainy season because the accumulated organic substances from the dry season were washed away by rainfall. By contrast, Paldang Lake exhibited a substantial decrease in TOC concentration due to dilution, which was influenced by watershed and rainfall characteristics. Across all streams and lakes, dissolved organic carbon (DOC) accounted for the highest proportion, at 77.5% of TOC, with RDOC making up 91% of DOC and 71% of TOC. Although POC contributed a small annual proportion to annual TOC, the concentration rapidly increased during late spring and early summer, with increases of 40.403%, 25.99%, and 27.388% in Cheongmi, Yanghwa, and Bokha, respectively. Continuous monitoring of RDOC is essential to identify seasonal fluctuations and changes due to rainfall events. Furthermore, intensive POC management during the rainy season, particularly in May and June, is potentially economical and efficient for water quality management.

• 환경위생공학
• /
• 제24권2호
• /
• pp.40-48
• /
• 2009

Unusual bloom of toxic cyanobacteria in water bodies have drawn attention of environmentalists world over. Major bloom of Anabaena, Microcystis in water storage reservoir, rivers and lake leading to adverse health effects have been reported from Australia, England and many part of the world. These cyanobacterial cells can release intercellular matter like toxin in water and these intercellular matter can increase the concentration of organic matter. Cellysis can occur when algal cells meet the disinfectants like chlorine in water treatment plant and the resultant rising up of DOC(Dissolved Organic Carbon) or TOC(Total Organic Carbon) can increase the formation of disinfection by products. Disinfectants that kill microorganisms react with the organic or inorganic matter in raw water. In general disinfectants oxidize the matter in raw water and the resultant products can be harmful to human. There are always conflict about which is more important, disinfection or minimizing disinfection by products. The best treatment process for raw water is the process of the lowest disinfection by products and also the the lowest microorganism. In this study the cultured cells, Microcytis Aeruginosa(MA), Anabaena Flos-aquae(AF), Anabaena Cylindrica(AC), and the cells obtained in Daechung Dam(DC) whose dominant species was Anabaena Cylindrica were subjected to chlorination. Chlorination oxidizes inorganic and organic compounds and destruct live cells in raw water. Chloroform was analyzed for the cultured cells which were treated with $20mg/\ell$ dose of chlorine. In general chloroform is easily formed when dissolved organic matter react with chlorine. The cultured cells contributes the concentration of dissolved organic carbon and also that of total organic carbon which might be potent precusors of chloroform formed. The correlations of the concentration of chloroform, DOC and TOC were investigate in this study.

• 한국환경과학회지
• /
• 제8권6호
• /
• pp.725-730
• /
• 1999

The advanced oxidation process (AOP) using ozone combined with hydrogen peroxide and ultraviolet treatment were evaluated for biodegradable dissolved organic carbon (EDOC) formation and dissolved organic carbon (DOC) removal. Oxidation treatment were conducted alone or combination with ozone, hydrogen peroxide and ultraviolet processes. Ozone dosage of ozone process was varied from $0.5mg/l{\ell}\cdot}min$ to $5mg/{\ell}{\cdot}min$. Ozone/hydrogen peroxide process was done using $20mg/{\ell}{\cdot}min$ of hydrogen peroxide concentration. Ozone/ultraviolet process was irradiated with $12mW/cm^2$ of density and 254nm. Ozone dosage was varied from $0.5mg/{\ell}{\cdot}min$ to $5mg/{\ell}{\cdot}min$ at the ozone/hydrogen peroxide and ozone/ultraviolet processes too. Contact time of all the process was 20 minutes. Oxidation treatment were performed on microfiltration effluent samples. BDOC formation was reached to an optimum at ozone dosage of $1.5mg/{\ell}{\cdot}min$ in the ozone/hydrogen peroxide process and $1mg/{\ell}{\cdot}min$ in ozone/ultraviolet process, after which BDOC formation was decreased at higher ozone dosages. But BDOC formation was increased with ozone dosages increasing in ozone process. The efficiency of DOC removal was higher AOPs than ozone process. Ozone/ultraviolet proces was the highest for DOC removal efficiency in each process. THMFP. removal efficiency by ozone/ultraviolet process was higher than that by each of ozone process and ozone/hydrogen peroxide process.

• 한국토양비료학회지
• /
• 제48권5호
• /
• pp.319-325
• /
• 2015

The safety of plant species used as a source for herbal medicines and dietary supplements has recently been questioned due to poisonings associated with the presence of cadmium (Cd) in these plants. These plants can derive Cd from their presence in the soil. Organic matter (OM) concentrations in soils could affect the availability of Cd for plants. To determine the effect of OM concentration in soil on the concentration of plant available Cd and uptake of this toxic element by medicinal plants, soil and plant samples were collected from 102 fields supporting for 5 species of medicinal plants in 6 province of South Korea. Concentrations of OM and dissolved organic carbon (DOC) in soils affected the phytoavailability of Cd. One M $NH_4OAc$ extractable Cd concentration in soil increased with increasing OM concentrations. There were significantly positive relationships between 1 M $NH_4OAc$ extractable Cd concentration and OM concentration in soil and between 1 M $NH_4OAc$ extractable Cd concentration and DOC concentration. Likewise, OM and DOC concentrations significantly affected Cd concentration in medicinal plant soils. Cadmium concentration in medicinal plants increased with increasing OM concentration in soil [Cd concentration $(mg\;kg^{-1})= 0.179+1.424{\times}10^{-3}$ OM concentrations, $R^2=0.042*$] and with DOC concentration [Cd concentration $(mg\;kg^{-1})= 0.150+5.870{\times}10^{-4}$ DOC concentrations, $R^2=0.124***$]. These results might result from Cd-DOC complex which is easily absorbed Cd form by plant root. Dissolved organic carbon concentration had more positive relationship with Cd concentration in medicinal plants and 1 M $NH_4OAc$ extractable Cd concentration in soils than OM. Cadmium concentration in all 5 species of medicinal plant (Atractylodes macrocephala Koidzumi, Astragalus membranaceus, Codonopsis lanceolata, Platycodon grandiflorum, and Rehmannia glutinosa) significantly increased with increasing DOC concentration in soil. From the above results, formation of Cd-DOC complex caused by OM application might be mainly attributed to increase in Cd concentration in medicinal plants.

• 대한환경공학회지
• /
• 제34권11호
• /
• pp.729-734
• /
• 2012

용존유기질소(DON)는 염소와 반응하여 인체에 유해한 질소계 소독부산물과 소독능을 저하시키는 유기성 클로라민을 생성할 수 있다. 이러한 물질의 생성을 줄이기 위해서는 소독공정 전에 DON의 제거가 필요하다. 본 연구는 DON을 함유하는 지표수와 재이용수를 이용하여 응집실험을 하고 알루미늄염(alum)과 고분자응집제(polyDADMAC)에 의한 DON의 제거특성을 조사하였다. 또한 DON, 용존유기탄소(DOC), 254 nm 자외선 흡광물질($UVA_{254}$)의 제거율 및 제거 기작을 비교하였다. 지표수와 재이용수 모두 alum 응집제의 주입농도를 증가시킴에 따라 DON, DOC, $UVA_{254}$ 제거율이 점진적으로 증가하였는데, 원수특성과 상관없이 소수성 유기물을 나타내는 척도인 $UVA_{254}$의 제거율이 가장 높았다. 지표수와 재이용수 모두 alum 응집제만 주입한 경우보다 고분자응집제를 같이 주입한 경우 DON의 제거율이 높게 나타났다. 고분자응집제의 전하중화가 작용하는 적정농도범위가 좁아 고분자응집제만 주입하기 보다는 무기응집제와 같이 주입하는 하는 것이 바람직하다. 상대적으로 생성된 후 오랜 시간이 지나지 않은 재이용수의 DON 제거율이 지표수의 DON 제거율보다 높았고, 지표수와 재이용수 모두 10,000 Da 이상 분자량의 DON 제거율이 높게 나타났다.

• 지질공학
• /
• 제23권4호
• /
• pp.427-434
• /
• 2013

구제역 매몰지에서 발생하는 침출수는 지하수, 호소수 및 하천수 등의 자연수에서 나타나는 유기물질의 성상(친수성 유기물질: 22~27%)과 달리 친수성유기물질을 44~50%로 포함하고 있었다. 자연수에서는 유기탄소가 미생물의 대사 등에 의해 감소되는 경향을 나타낸다. 하지만, 매몰 초기에 발생하는 구제역 침출수(leachate-1, 2)에서는 RTOC와 RDOC의 농도가 초기 TOC, DOC 농도보다 높게 나타나는 특성이 있다. 매몰시간이 경과하면서 RTOC와 RDOC는 초기 TOC와 DOC보다 낮게 검출되었다. 구제역 침출수 중 386일이 경과한 leachate-6의 RDOC는 RTOC 중에 91%를 차지하였다. 이것은 안정화된 매몰지 환경에서도 침출수 중에는 여전히 미생물 등의 활동에 의해 제거되기 어려운 형태의 난분해성 유기물질이 유기물질의 대부분을 차지하고 있음을 알 수 있다. 따라서 구제역 침출수의 난분해성 유기물질의 검출수준과 성상은 지표수 및 지하수에 대한 영향을 파악하는 정보로서 유효하며, 침출수 내 환경을 이해하는 데에도 기여할 것으로 기대된다.