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由結果可知，由馴養之chemostat分離出三株能降解之菌株，依次命名為N-2、N-4及N-5菌。其中以N-4菌降解土壤中之能力最好，其次分別為N-2菌及N-5菌。當混合菌種和僅有單一菌株存在時，降解土壤中之並無顯著不同，混合族群若有N-4菌存在於土壤中，其降解狀況最好，N-4菌於降解方面扮演了關鍵性角色。N-4菌經由PCA 增殖，加入土壤中後做為生物復育菌種，其在土壤環境適應能力極佳，且當土壤中濃度達1000 μg/g-soil對於N-4菌並不會產生抑制作用，擬零階反應速率常數可達2.11 μg/g-soil-hr。添加於土壤中之溶液或無機鹽之pH值介於3~11時，對於N-4菌降解土壤中之影響不大。
利用混合菌對於土壤中之菲加以降解，若能添加足夠量之微生物量，對於菲之降解有促進作用。現地菌也能夠有效地利用土壤中之菲做為碳源及能源，但當土壤中之菲濃度達300 μg/g-soil時，添加馴化菌種於土壤中並沒有任何促進之作用。添加馴化菌會對於現地生物降解土壤中菲之總量產生了抑制作用，未添加馴化菌之現地微生物組可將菲降解至更低程度。重複添加具有活性之馴化菌，可達到完全復育受菲污染土壤之目標。存在情況下，可促使土壤中之菲能夠更快被微生物所利用，且當土壤中菲濃度為200 μg/g-soil時，濃度為300 μg/g-soil效果最佳。
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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