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  • 學位論文

台灣藜移除土壤重金屬及生質酒精生產之探討

Heavy metal removal from soil and bioethanol production by Chenopodium formosanum Koidz.

指導教授 : 柯淳涵

摘要


台灣藜 (Chenopodium formosanum Koidz.)具有適應力強、生長速度快等優點。本研究以台灣藜在不同重金屬濃度條件下,進行播種栽植實驗,探討台灣藜針對不同重金屬移除之能力,及探究其作為一多目標生質酒精料源作物之可行性。 利用台灣藜以重金屬污染土壤鎳、鉛及鋅進行栽植觀察蓄積效果,台灣藜在高濃度鉛 (10000 mg/kg soil)的環境存活情形良好,且具有豐富的吸收效果,葉部吸收重金屬為土壤濃度的0.46-3.7倍,穗部為0.88-2.94倍,根部為0.41-0.50倍,在高濃度Ni及Zn的環境下,則生長受到抑制甚至導致死亡。 以SPORL法進行前處理後可去除較多的木質素,木質素的含量可降至9.18%,以酸蒸氣爆碎前處理,木質素的含量將會降低,全纖維素含量也相對較SPORL法來的高。酵素水解試驗以酸蒸氣爆碎前處理,所獲得的葡萄糖轉換率最佳。木糖的轉換率以SPORL法前處理比蒸氣爆碎前處理來較佳。 以共發酵菌種 (Escherichia coli KO11)進行同時糖化與發酵,經酸蒸氣爆碎處理試材的乙醇轉換率最高,每公斤的的試材可得到0.16公升的酒精,以SPORL法進行蒸煮前處理,每公斤的的試材可得到0.14公升的酒精。 以含重金屬植體進行同時糖化與共發酵試驗,顯示含有重金屬Ni、Pb、Zn的植體對於發酵效率具有抑制影響,其中以Zn的影響最為明顯,Ni的影響次之,Pb 對於發酵的影響較小,雖然重金屬對發酵效率具有影響,但並非完全的抑制,因此對於重金屬污染土壤以植生復育後植體的再利用仍有相當的潛力。

並列摘要


Taiwanese chenopod (Chenopodium formosanum Koidz.) has strong productivity and great adeptness. Taiwanese chenopod was seeded in soils with different heavy metal concentrations. Capabilities for heavy metal removals and bioethanol raw material supply were investigated to survey the feasibility for multi-purpose application for Taiwanese chenopod. Taiwanese chenopod was grown in soils containing Ni, Pd and Zinc, and the accumulation in Taiwanese chenopod biomass was investigated. Taiwanese chenopod grew well under high concentration of Pd at 10000 mg/kg soil. High uptakes were observed: leaves absorbed 0.46 to 3.7 times of soil Pb concentration, tassel absorbed 0.88 to 2.94 times of soil Pb concentration, and root absorbed 0.41 to 0.50 times of soil Pb concentration. However, Taiwanese chenopod could not endure high concentration of Ni and Zn and showed inhibited growth and death. Higher lignin removals were found using SPORL (sulfite pretreatment to overcome recalcitrance of lignocellulose), with the lowest pretreated biomass lignin contents found at 9.18 %. Acid steam explosion could also reduce lignin and increase holocellulose contents. For enzymatic hydrolysis, steam exploded biomass yielded higher glucose conversion. While SPROL pretreated biomass yielded higher xylose conversion. A co-fermentation strain, Escherichia coli KO1, was to conduct simultaneous saccharification and fermentation. Final ethanol yield from acid exploded and SPROL  treated Taiwanese chenopod biomass could reach 0.16 and 0.14 l ethanol per dried biomass. Simultaneous saccharification and fermentation was also conducted on heavy metal conducted biomass. Presence of Ni, Pd and Zn was showed inhibiting fermentation yields. Negative impacts of heavy metals on fermentation yields were demonstrated with the following orders: Zn, Ni and Pb. Although negative impacts of heavy metals were found, this study still found bioethanol converting potentials of resulted biomass after phytoremediation.

參考文獻


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