Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/48305
標題: 高溫菌腐蝕對策分析
Strategies Analysis of Microbiological Influenced Corrosion by Thermophilic Bacteria
作者: 李季眉
顏秀崗
關鍵字: 商品化
microbiological influenced corrosion
環保工程, 生物技術, 材料科技
微生物腐蝕
交流阻抗
動態電位極化
AC Impedance
potentiodynamic polarization
摘要: 摘 要目前某一電廠廠用冷卻水添加鉬酸鹽系防蝕抑制劑,但因廠用水中微生物滋生,造成廠用水管路發生微生物腐蝕現象。由此冷卻水系統中的泥濘物已分離出13株中溫菌及10株高溫菌。本研究的主要的目的是抑制生物膜的生長,以解決冷卻水系統中微生物腐蝕的問題,並以電化學動態循環極化、交流阻抗、腐蝕電位趨勢圖及掃描式電子顯微鏡觀察其腐蝕型態,以評估腐蝕情形。試驗殺菌劑長時間抑制各高溫性菌株的效果,以及殺菌劑和腐蝕抑制劑搭配使用之效果,以尋找適當殺菌劑及決定最佳抑制劑用量。結果顯示,以殺菌劑A的效果最好,其濃度在50ppm以上無論有無添加鉬酸鹽抑制劑對於10株高溫菌在實驗進行的1600小時內皆可有效殺菌。以純種菌株(TPH-2、TPH-5-2、TPH-13-3)進行微生物模擬腐蝕試驗,探討殺菌劑對微生物腐蝕作用的抑制效果實驗結果顯示,對純種菌株而言,殺菌劑T、殺菌劑N與殺菌劑A可有效殺菌但無法有效抗蝕。為了瞭解在生物膜生成前殺菌的效果,在電廠中將冷卻水分流出來,先分別經過紫外光或臭氧殺菌,再送入一連續流反應器,將碳鋼試片放入反應器中30-40天,評估已殺菌的冷卻水對生物膜的生成及碳鋼腐蝕情形。比較冷卻水經紫外光滅菌前後生成之生物膜,其腐蝕實驗數據並無太大差距,故推論紫外光在此狀況下對冷卻水的殺菌效果不佳,無法有效抑制生物膜的生成,亦無法防止碳鋼之腐蝕。然而,冷卻水經臭氧處理的殺菌效果要比紫外光有效,碳鋼試片在經過臭氧處理的冷卻水中有極佳的抗蝕效果。而利用浸泡殺菌劑來去除碳鋼上已附著的生物膜,腐蝕數據顯示出都達到有效的抑制腐蝕效果,其中殺菌劑A可最有效達到除去碳鋼表面的生物膜,並使腐蝕電位處於較貴重的電位保護,顯示可有效抑制碳鋼腐蝕。亞硝酸鹽對冷卻水系統中微生物生長現象的影響實驗中,TPH-7、TPH-9-2能被亞硝酸鹽促進生長,其他菌株則皆被抑制。而在無氧環境下,TPH-7及TPM-8可以亞硝酸鹽做為電子接受者而生長,其他菌株則無法在無氧條件下以亞硝酸鹽作為電子接受者而生長;而TPH-2、TPH-5-2、TPH-5-4、TPH-5-5及TPH-7可以在無氧條件下以硝酸鹽為電子接受者而生長。
AbstractIn the presence, molybdate is added as corrosion inhibitor to the cooling water syatem of one power plant. However, it is shown that the growth of microorganisms induced microbiologically influenced corrosion (MIC) in the water pipelines of cooling water system. Thirteen strains of mesophiles and ten strains of thermophiles have been isolated from the slime of this system. Antimicrobial agents which can inhibit the growth of isolated mesophiles have been found, but effective antimicrobial agents for the isolated thermophiles need to be investigated. The main purpose of this research is to inhibit the incidence of biofilm growth, in order to solve the problem of biological corrosion of the cooling water system. The corrosion characteristics are evaluated by potentiodynamic polarization test, AC-impedance tests, corrosion potential trends, and scanning electron microscope observation. The long-term inhibitory effects of antimicrobial agent alone as well as in the presence of corrosion inhibitor to each strain of thermophilic bacteria are examined, in order to find appropriate antimicrobial agent and to determine the optimal dosage of corrosion inhibitor. The results indicated that ten strains of thermophiles could be inhibited by more than 50 ppm antimicrobial agent A within 1600 hours whether molybdate is present or not. MIC was simulated by inoculation of the isolated strain, TPH-2, TPH-5-2, TPH-13-3, with or without antimicrobial agent to see the inhibitory effect of corrosion on carbon steel by antimicrobial agents. The growth of isolated strains could be inhibited by antimicrobial agent T, antimicrobial agent N and antimicrobial agent A, but the corrosion of carbon steel was not inhibited. In order to know the effect of disinfection before a biofilm develops, the cooling water has been bypassed and disinfected by UV and ozone respectively, and biofilm formation and corrosion on carbon steel samples immersed in a continuous reactor have been evaluated by exposing steel samples to disinfected cooling water for 30-40 days. The formation of a biofilm on steel samples immersed in disinfected cooling water by UV was not different as compared with that in cooling water without disinfectant. It was shown that the effect of disinfection in the cooling water by UV was ineffective, neither biofilm formation nor corrosion on catbon steel could be inhibited. However, the effect of disinfection in cooling water by ozone was more effective than UV. Steel samples have been protected from corrosion when it immersed in disinfected cooling water by ozone. Different antimicrobial agents for the removal of biofilms already adhered to steel samples were effective. Antimicrobial agent A was the most effective among them, it made corrosion potentials of carbon steel be maintained at noble region and corrosion on catbon steel be inhibited . The effect of nitrite on the growth of isolated thermophilic bacteria has been carried out. The growth of strain TPH-7,TPH-9-2 could be promoted by nitrite, others were all suppressed. Under anoxic environment, strain TPH-7, TPM-8 could use nitrite as aelectron acceptor, others couldn?HH?HHt. Besides, strain TPH-2, TPH-5-2,TPH-5-4 and TPH-7 could use nitrate as a electron acceptor under anoxic environment.
URI: http://hdl.handle.net/11455/48305
其他識別: TPC-546-93-2819-01A
文章連結: http://grbsearch.stpi.narl.org.tw/GRB/result.jsp?id=1150711&plan_no=TPC-546-93-2819-01A&plan_year=93&projkey=PG9410-0029&target=plan&highStr=*&check=0&pnchDesc=%E9%AB%98%E6%BA%AB%E8%8F%8C%E8%85%90%E8%9D%95%E5%B0%8D%E7%AD%96%E5%88%86%E6%9E%90
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