二甲基亞楓(Dimethyl sulfoxide, DMSO)為TFT-LCD工業廢水中主要成分之一，其生物降解之過程中，DMS為主要的中間代謝產物，普遍被認為會造成環境惡臭，且同時抑制硝化作用(Nitrification)，使廢水中另外兩種汙染物，乙醇胺(Monoethanolamine, MEA)和氫氧化四甲基銨(Tetramethyl-ammonium hydroxide, TMAH)無法被完全降解。因此，本研究主要探討DMSO的降解以及DMS抑制硝化作用的機制，。在能有效降解TFT-LCD工業廢水的二個連續批次反應器(Sequencing batch reactor, SBR)中，DMSO與DMS之主要降解菌群為Hyphomicrobium sp與Thiobacillus sp，此外藉由t-RFLP(terminal restriction fragment length polymorphism)的監測，發現在消長過程中此二菌群於在不同條件下各別為優勢族群。
在本研究中，使用SYBR Green進行real-time PCR，定量Hyphomicrobium sp與Thiobacillus sp於SBR與廢水處理實場中之變化。在四組批次中，其中三組可發現Hyphomicrobium sp與Thiobacillus sp的競爭與硝化作用有顯著影響。當硝化作用不佳時，Thiobacillus sp為主要優勢菌群，反之，Hyphomicrobium sp則在良好硝化作用時成為優勢菌群。造成此現象的可能原因推測是，在系統中缺乏硝酸時DMSO取代硝酸成為主要電子接受者，改變DMS與DMSO間之比例，進而導致優勢族群的變化。在批次實驗中，當DMS或DMSO做為唯一基質時，兩菌群的rRNA表現量有相對減少的趨勢，且只有Hyphomicrobium sp能在第二或第三次加入基質時，仍持續釋出rRNA；推測廢水中其他物質，如TMAH及MEA可能提供微生物生長額外的條件，而廢水中複雜的微生物族群亦可能使對特定菌群(DMSO/DMS降解菌)的監測更加困難。
而在DMS抑制硝化作用的批次實驗中，結合RT-PCR(Reverse transcription polymerase chain reaction)與t-RFLP的分子生物技術，用以監測硝化族群的功能性基因表現(amo subunit A, amoA)之變化。當DMS存在時，amoA基因的表現量會受到影響，且因不同硝化菌有不同影響：Nitrosomonas europeae (T-RF 491)會完全受到抑制，而Nitrosomonas europeae (T-RF 270)雖然有基因的表現，表現量仍少於無DMS抑制時之amoA基因表現量。

Dimethylsulfide (DMS) is the main intermediates in dimethyl sulfoxide (DMSO) biodegradation. DMS is known as odor compound and suspected as inhibitor in nitrification process. Nitrification process is one of requirement to get complete degradation process for other two major compounds in TFT-LCD wastewater, monoethanolamine (MEA) and tetramethyl-ammonium hydroxide (TMAH). Because of this issue, DMSO degradation becomes the main concern in this study. The mechanisms of nitrification inhibition by DMS is also one of the main topic that was being studied.
From two sequencing batch reactor, anoxic/oxic SBR and aerobic SBR which can reach complete degradation of TFT-LCD wastewater, Hyphomicrobium sp and Thiobacillus sp were found as DMSO/DMS degrading bacteria in the system process. By T-RFLP analysis for monitoring total bacteria from SBR time by time, the dynamics of Hyphomicrobium sp and Thiobacillus sp were detected.
In this research, real time PCR with SYBR Green I methods is developed to quantify Hyphomicrobium sp and Thiobacillus sp in the system and applied to monitor two laboratory scale sequencing batch reactors (SBRs) and two full-scale wastewater treatment plants. From monitoring works, correlation of nitrification with Hyphomicrobium sp and Thiobacillus sp competition was found in three of four monitored treatment system. Thiobacillus sp was dominated while bad nitrification appears and Hyphomicrobium sp was dominated when good nitrification reached. Hypothesis was developed that domination of Hyphomicrobium sp and Thiobacillus sp is related to dominant sulfur compound (DMSO or DMS) in the system. This hypothesis built from the fact that nitrate concentration in the system affected amount of DMS in the system based on the roles of DMSO as main electron acceptor in the system while nitrate was not present in the system.
Batch experiment using SBRs sludge was performed to get understanding about DMSO and DMS effect to Hyphomicrobium sp and Thiobacillus sp, From this batch experiment, TFT-LCD wastewater treatment system was found as complex system. While only DMS or DMSO as substrate, only Hyphomicrobium sp that can express rRNA. By applying second or third time feeding of DMS/DMSO, amount of rRNA expression from both of Hyphomicrobium sp and Thiobacillus sp was decreasing. DMSO or DMS alone as a substrate compound was not enough to maintain the growth of Hyphomicrobium sp and Thiobacillus sp. TMAH or MEA might be the other important substance for their growth, so the presence of TMAH or MEA in treatment system was necessary. Complex microbial community was also important factor that make difficulties to examine specific community response, in this case only DMSO/DMS degrading bacteria.
The study of inhibition of nitrification by DMS was performed using batch experiments with sludges and pure culture. From sludge batch test, by monitoring amo subunit A (amoA) mRNA using real-time reverse transcription polymerase chain reaction and terminal restriction fragment length polymorphism (T-RFLP), while DMS present, the amount of amoA expression was inhibited. Inhibition effect of DMS was found different between different ammonia oxidizing bacteri (AOB) strains. Nitrosomonas europeae (T-RF 491) completely lost the ability to express amoA mRNA when DMS was present in the system, while Nitrosomonas europeae (T-RF 270) still had ability to express amoA mRNA although the expression level was much lower than that in the batch without DMS.. Nitrosomonas europeae (T-RF 491) and Nitrosomonas europeae (T-RF 270) was the same species but different strain of bacteria.

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