| Summary: | 碩士 === 國立中興大學 === 環境工程學系 === 88 === The objective of this study was to discuss the feasibility of contaminated by naphthalene- or phenanthrene-contaminated soils. A respirometer was used to measure the oxygen demand during the process of biodegradation in soils. The biodegradation rate and microbial activity were also studied by the repirometer.
Three strains named N-2、N-4 and N-5 were isolated from chemostat which was acclimated by both naphthalene and phenanthrene. The strain N-4 had the best biodegradable capacity for removal of naphthalene, the next was the strain N-2 and N-5. The biodegradation of naphthalene in soils inoculated by pure-culture and mixed-culture had a similar result. When the strain N-4 was in the mixed-culture, the strain N-4 played a key role for the removal of naphthalene and it had the highest biodegradation performance. The strain N-4 that was used as the cell source was collected from PCA (Plate Count Agar). These cells could be acclimated in the soil environment very quickly. When the concentration of naphthalene reached 1000 mg/g-soil, the inhibition effect was not observed. The simulated zero-order biodegradation rate constant was 2.11 mg-Nap/g-soil-hr. The pH of inorganic nutrient solution added to the soil was in the range of 3~11 did not have significant effects on the biodegradation of naphthalene.
The biodegradation of phenanthrene was studied by a mixed culture. The biodegradation of phenanthrene was promoted through the addition of degraders. The indigenous cells in soil also had contribution on degradation of phenanthrene. When the concentration of phenanthrene reached 300 mg/g-soil, addition of acclimated cells did not enhance biodegradation of phenanthrene. And addition of acclimated cells resulted in a decrease in the total amount of phenanthrene degraded, the indigenous cells in soil could degrade phenanthrene to reach a much lower concentration. Repeat addition of active acclimated cells reached the goal of complete bioremediation of phenanthrene in soils. The present of naphthalene increased the removal rate of phenanthrene. When the concentration of phenanthrene was 200 mg/g-soil, the present of naphthalene at 300 mg/g-soil had the best enhancement on the phenanthrene removal.
The oxygen demand consumed by biodegradation of naphthalene in soil was recorded by a respirometer. Under 60 % WHC, the ratio of the result gained from respiration study to the result calculated from McCarty''s stoichiometry equation was in the range of 0.62~1.23. The respirometer could be used to measure the oxygen demand for the biodegradation study in soils. A soil column was designed to simulate soil bioventing, the ratio of the actual oxygen demand to the theoretical value was in the range of 0.75~0.85. Air leakage was found in the soil column experiment resulting in a difficult to explore the result. The soil column was needed to redesign to study the soil bioventing in the biodegradation process.
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