海水中에서 油處理劑 및 油處理劑/Bunker-C油 混合物의 生分解度와 溶存酸素消費에 관한 硏究(Ⅰ) - 유처리제의 생분해도와 용존산소소비 -

Study on the Biodegradability of Dispersants and Dispersant/Bunker-C Oil Mixtures and the Dissolved Oxygen Consumption in the Seawater(Ⅰ) - The Biodegradability of Dispersants and the Dissolved Oxygen Consumption in the Seawater -

As the dispersants and the dispersant/oil mixtures are degraded naturally by the microorganisms in the seawater, the consumption of dissolved oxygen may cause marine organisms to be damaged especially in the waters where the dissolved oxygen level is low due to the pollution and the restriction of seawater flow. The biodegradation experiment, the TOD analysis and the element analysis for three dispersants(SG, GL and WC) and a nonionic surfactant(OA-5) were conducted for the purposes of evaluating the biodegradability of dispersants and studying the effect of dispersants on dissolved oxygen in the seawater. The results of biodegradation experiment showed 1mg of dispersants to be equivalent to O.403-0.595mg of BOD5 and to O.703-0.855mg of BOD20, and 1mg of. nonionic surfactant to be equivalent to 0.5Omg of BOD5 and to O.97mg of BOD20 in the natural seawater. The results of TOD analysis showed 1mg of dispersants to be 2.37-2.8Omg of TOD and 1mg of nonionic surfactant to be 2.45mg of TOD. The results of element analysis showed carbon content and hydrogen content to be 67.6-76.5% and 10.2-12.2% for dispersants, and 65.3% and 10.3% for nonionic surfactant, respectively. No nitrogen element was detected in dispersants and a nonionic surfactant. The biodegradability of dispersants shown as the ratio of BOD5/TOD was found to be in the range of 17-21%, and that of nonionic surfactant was found to be about 20%. This means that dispersants and nonionic surfactant belong in the organic matter group of middle-biodegradability. The deoxygenation rates(K₁) and ultimate oxygen demands(L₁) obtained through the biodegration experiment and Thomas slope method were found to be 0.121~0.171/day and 3.155~3.810mg/l for 4mg/l of dispersants and to be 0.181/day and 1.911mg/l for 2mg/l of nonionic surfactant in the seawater, respectively.