不同溫度下重金屬銅突增負荷對生物除磷酵素動力反應之影響

本研究主要探討不同溫度條件下，重金屬銅突增負荷對活性污泥厭/好氧相釋/攝磷機制、PHAs合成/分解以及胞內酵素乙醯輔酶A合成酶、聚磷酸激酶活性之影響。實驗進行以污泥停留時間10天馴養達穩定之批次進流式回分式活性污泥系統(B-SBR)之活性污泥為研究對象，其對COD及PO43-之去除率均可維持在90%以上。為研擬B-SBR系統操作控制生物除磷程序之基準，瞭解低濃度重金屬離子對活性污泥除磷能力的影響及毒性抑制效應，本研究分別利用比釋/攝磷速率、PHAs之合成/分解率等批次實驗，藉控制不同溫度條件(10∼30℃)，探討微生物於溫度變異環境下對重金屬Cu2+濃度(0∼4 mgl-1)之耐受性。結果顯示，厭氧比基質利用率、比攝/釋磷率、PHAs合成/分解率、ACS酵素活性與PPK酵素活性在10℃與20℃範圍下均隨溫度升高而增加，而20℃與30℃則無顯著差異。而在添加重金屬狀況下，厭氧比基質利用率、比攝磷率、PHAs合成/分解率、ACS酵素活性與PPK酵素活性均隨濃度提高而降低，唯比釋磷率於Cu2+添加下未受影響。本研究亦發現厭氧相PHAs合成與ACS活性有顯著相關性，即厭氧階段PHAs合成的抑制乃由於ACS酵素活性受溫度或毒性影響所致；而好氧相比攝磷率與PPK活性有顯著相關性，即好氧攝磷的抑制乃由於PPK酵素活性受溫度或毒性影響所致。並且利用雙倒數線性圖與抑制係數的計算，顯示Cu2+對ACS與PPK酵素活性屬於混合性競爭型抑制，且其抑制特性皆以自由酵素據較強的結合力。由此可知溫度與重金屬對生物除磷機制之影響途徑為自身代謝能力的降低，以及佔據酵素與受質之結合位而使酵素失去活性，而聚磷酸鹽作為在毒性物質作為入侵時之解毒劑，導致即使進入好氧段仍持續分解產生釋磷現象，如此亦印證EBPR程序易受毒性物質影響而失敗之原因。

關鍵字

重金屬；生物除磷； PHAs ；乙醯輔酶A合成酶聚磷酸激酶抑制型態

並列摘要

The purpose of this study mainly investigated the effects of heavy metals copper invasion on phosphorus release/uptake, polyhydroxyalkanoates（PHAs）synthesis/ degradation, and intercellular enzymatic activity of Acetyl-CoA Synthetase and Polyphosphate Kinase of the activated sludge during the anaerobic/aerobic reactions under short-term temperature conditions. The efficiency of the activated sludge of B-SBR system which was acclimated until steady state basing on the condition of sludge retention time（SRT）10 days showed that the removal ratio of COD and PO43--P could be maintained above 90%. In order to realize the optimal operation in EBPR system when heavy metal invaded, this study focused on the mechanism of phosphate release/uptake, PHAs synthesis/degradation to investigate the effects of microorganism suffering from different copper concentrations (0∼4 mgl-1) and temperatures (10℃~30℃）. Experimental results showed that under none added heavy metals, the specific substrate utilization rate, specific release/uptake phosphorus rates, PHAs synthesis / degradation rates, and enzymatic activity of Acetyl-CoA Synthetase and Polyphosphate Kinase significantly increased from 10℃ to 20℃ while none of heavy metal was adding; but there was no significant difference bewteen 20℃ and 30℃. In addition, specific substrate utilization rate, specific phosphorus uptake rate, PHAs synthesis/degradation rates, and enzymatic activity of Acetyl-CoA Synthetase and Polyphosphate Kinase were distinctly decreased while concentration of heavy metals increased. However, the addition of copper metal did not influence the mechanism of phosphorus release. This research also discovered two strong relationships between PHAs synthesis rate and enzymatic activity of Acetyl-CoA Synthetase, and between specific uptake phosphorus rate and Polyphosphate Kinase. It was illustrated that the inhibition of PHAs synthesis rate resulted from the temperature or toxicity effect on Acetyl-CoA Synthetase activity. Also, the phenomenon was similar to the relation between specific uptake phosphorus rate and Polyphosphate Kinase activity. In addition, applied of Lineweaver-Burk equation and coefficient of inhibition, it was demonstrated that the type of inhibition was mix-competitive inhibition, and the inhibitor mainly combined with free enzyme when the copper invaded. Thus, it could be known that the low temperature caused the metabolism in organism decreased; and the copper ions occupied the sites for combing enzyme. Besides, polyphosphate in intercellular could carry out the detoxification process when the inhibitor existed. It caused the phosphate continuously released even at aerobic stage. Consequently, this study proved that the mechanism of enhanced biological phosphate removal fluctuated easily by toxic inhibitors invasion.

並列關鍵字

heavy metals ； enhanced biological phosphate removal ； PHAs ； Acetyl-CoA Synthetase ； Polyphosphate Kinase,Type of inhibition

參考文獻

Adeline S.M., Chua, Takabatake H., Satoh H., and Mino T., 2003. Production of polyhdroxyalkanoates (PHA) by of pH, sludge retention time (SRT), and acetate concentration in influent. Wat. Res. 37, 3602-3611.

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不同溫度下重金屬銅突增負荷對生物除磷酵素動力反應之影響

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