Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/4916
標題: 厭氧/好氧併同處理四氯乙烯之研究
作者: 王毅賢
Wang, yi-shian
關鍵字: 四氯乙烯;上流式厭氧污泥床法;氧化還原電位
出版社: 環境工程學系
摘要: 
四氯乙烯在好氧環境中不易被微生物利用或降解,但是卻可以在厭氧的環境下,被當做電子接受者,來進行還原性脫氯的降解反應。而顆粒性污泥由於其特殊的顆粒化形態,因此當水中氧化還原電位升高時,顆粒性污泥外層會長出好氧微生物,消耗外在環境中的溶氧,造成內層仍能維持一完全厭氧的環境,而同時進行厭氧及好氧的反應來進行四氯乙烯及其中間代謝產物的降解。本研究之主要目的在於將上流式厭氧污泥床法(UASB)操作在不同氧化還原電位下,探討對顆粒性污泥降解四氯乙烯的影響,並以批次實驗探討電子接受者(硫酸根與硝酸根)與電子供給者(醋酸、乳酸及蔗糖)所造成的影響。
批次反應瓶添加241 nmol四氯乙烯,顆粒污泥對四氯乙烯之轉化率介於1.94 - 2.24 nmol PCE/g-VS.d,但是當批次瓶中硝酸鹽濃度達到1000 mg/L時,甲烷化明顯的受氧化還原電位改變的影響而受到抑制,而四氯乙烯的轉化亦受到抑制。硫酸鹽的添加並不會影響甲烷化,因此對微生物降解四氯乙烯並沒有明顯的影響。不同電子供給者實驗中,四氯乙烯的降解及三氯乙烯的生成以醋酸的效果最佳,乳酸次之,蔗糖的添加對四氯乙烯降解效果最差,這三種電子供給者影響四氯乙烯的降解及三氯乙烯的生成,但是對於乙烯的生成卻沒有明顯的影響。
連續流實驗利用過氧化氫的添加將UASB操作在不同的氧化還原電位,厭氧的操作條件下,四氯乙烯的降解效果最佳(7675 nmol/L.day),隨著氧化還原電位的提升,四氯乙烯的去除效率隨之降低,生成物方面,厭氧操作下,只測到三氯乙烯的累積,但是若是操作在好氧的階段,則有大量的氯乙烯生成(869 nmol/ L.day),可見外在的好氧環境對於將四氯乙烯或其中間產物降解至氯乙烯之菌種有助益。就四氯乙烯的去除而言,以厭氧操作最佳,但是若是以四氯乙烯的完全脫氯而言,將UASB操作在微好氧反而能得到較佳的結果。

Tetrachloroethylene (PCE) is recalcitrantly used or degradated by microorganisms in the aerobic environment, but can be used as the electron acceptor to proceed reductive dechlorination. Because of the special granular property of the granular sludge, aerobic microorganisms would grow in the outside of granular sludge and consume the dissolved oxygen in the outer environment at the high oxidative reductive potential (ORP) conditions. Therefore if can keep an entire anaerobic environment inside to conduct the reductive degradation of PCE and keep the aerobic reaction outside. The objective of this study is to discuss the effect of PCE degradation by operating the upflow anaerobic sludge bed reactor (UASB) and the batch reactor in the different ORP conditions, different electron acceptors (nitrate and sulfate), and the different electron donors (acetate, lactate, and sucrose).
PCE (241 nmol/bottle) was degraded at the rate 1.94-2.24 nmole PCE/g-VS.d at reductive conditions. When the nitrate concentration reach to 1000 mg/L, methanogensis was inhibited by the change of the ORP, and then to inhibit the PCE degradation. Sulfate addition did not affect the methanogensis, so there is no obvious effect on the PCE biodegradation. In the study of the different electron donors, it was found the addition of significantly acetate enhanced the PCE biodegradation. Lactate was the next, following by sucrose. The removal of PCE also resulted in the TCE production.
In the continuous flow column study, the UASB was operated at different ORP conditions by addition of hydrogen peroxide (H2O2). However, the best degradation (7675 nmol/L.d) was observed in the anaerobic condition. With the ORP increased, the PCE degradation rate and the removal efficiency decreased. For the intermediates production, TCE was the only product in the entire anaerobic condition. However, a significant quantity of vinyl chloride (VC) was accumulated in the aerobic condition (869 nmol/L.d). For the complete dechlorination of PCE, operating UASB in the slightly aerobic condition could result in the removal of PCE.
URI: http://hdl.handle.net/11455/4916
Appears in Collections:環境工程學系所

Show full item record
 

Google ScholarTM

Check


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.