| Summary: | 碩士 === 東吳大學 === 微生物學系 === 87 === Abstract
In order to assess the possible bioremediation for polynuclear aromatic hydrocarbons (PAHs) contaminated sediments, acenaphthene, fluorene, phenanthrene, anthracene and fluoranthene were spiked to sediments collected from monitoring sites of middle and down stream of Ke-Lung River which located in northern part of Taiwan. The collected sediments consortia were acclimatized in laboratory with phenanthrene for 6 months before testing. The results showed the optimal conditions for PAHs biodegradation using K8 sediment were 35-40 oC and higher acidic or alkali pH under aerobic incubation. For K12 sediment(estuarine sediment), 30-40 oC and pH 7.0-9.0 were found. The rates(K) of PAHs biodegradation in K8 sediments (freshwater sediment) were observed as anthracene(0.586 day-1) > fluoranthene (0.349 day-1) > acenaphthene(0.374 day-1) > phenanthrene (0.148 day-1) > fluorene(0.014 day-1). For K12 sediment, rates(K) of PAHs showed as anthracene (0.593 day-1) > fluoranthene (0.549 day-1) > phenanthrene (0.549 day-1) > fluorene (0.409 day-1) > acenaphthene (0.109 day-1). Acetate, lactate, pyruvate or yeast extract added to incubation vials as carbon source could enhance acenaphthene and phenanthrene biodegradation, but the other PAHs were reduced. Adding nitrate as nitrogen source also enhance PAHs biodegradation for K8 sediment. However, for K12 sediment, only acenaphthene and fluoranthene showed increase biodegradation rate. The result also indicated that PAHs biodegradation rate in the control vial (liquid medium without sediment) was increased.
For anaerobic incubation, after six months acclimation K8 sediment showed much higher biodegradation rate when unacclimatized same sediment were compared. Both for K8 and K12 sediment under different pH control showed biodegradation rate in the order of alkali > acidic > neutral. The optimal temperature for biodegradation is 35 oC. The rates(K) of PAHs anaerobic biodegradation in K8 sediments were observed as anthracene (0.0743 day-1) > acenaphthene (0.0646 day-1) > fluoranthene (0.0471 day-1) > phenanthrene (0.0266 day-1) > fluorene (0.0022 day-1). However no significant difference were found for K12 sediment. The rates(K) were at range of 0.10-0.060 day-1. Comparison influence of PAHs concentration (0.5-10mg/L) on biodegradation under simulated denitrifying, sulfodogenic or methanogenic conditions, for 0.5-2 mg/L PAHs in incubation vials, K8 or K12 sediment showed higher biodegradation rate. The addition of electron donors acetate, lactate, pyruvate, or electron acceptors manganese oxide or ferric chloride to incubation vials, all enhance PAHs biodegradation.
In conclusion, K12 sediment showed higher biodegradation capacity than K8 sediment for all 5 PAHs under aerobic or anaerobic conditions in laboratory studies. All results could be used for further application of bioremediation for clean-up of PAH-contaminated sediments.
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