| Summary: | 碩士 === 長榮大學 === 職業安全與衛生學系碩士班 === 100 === Sediment-bound polycyclic aromatic hydrocarbons (PAHs) pose potential ecological risks to benthic organisms. The biodegradation of PAHs in sediment is affected by dissolved oxygen concentration in water column. Activating the aerobic microbial community using a patented Bubble-free Oxygen Dissolution Apparatus, that allows dissolution of high oxygen concentrations into water, may be a promising technique to encourage bioremediation of organic contaminants in sediment.
In this study, laboratory batch experiment was conducted to derive loss rate constants of pheanthrene, pyrene, and benzo[a]pyrene spiked onto sediments collected from Erhjin River under low (<1mg/L), saturated (8mg/L), and oversaturated (>30mg/L) dissolved oxygen conditions. Sediment-bound PAH dynamic model, based on the loss rates and chemical parameters collected in the laboratory-scale batch study, was established to evaluate the effectiveness of the Bubble-free Oxygen Dissolution Apparatus.
The simulation results showed that PAHs with the contamination levels as high as three times of the Effect Range-Median need 1.3days to drop below the medium-low ecological risk criteria under saturated dissolved oxygen conditions, while the treatment time cuts down to 1.2 days upon the application of the Bubble-free Oxygen Dissolution Apparatus. Low dissolved oxygen condition, however, cannot bring down the PAH concentration down to the safety level. The study demonstrated that the Bubble-free Oxygen Dissolution Apparatus can effectively stimulate PAH losses from benthic environment and can be a potential technology for remediation of persist organic pollutants in sediment.
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