不同溫度下重金屬Zn突增負荷對磷積蓄菌酵素動力反應之影響

Impacts of heavy metals Zn invasion on enzymatic kinetic reaction of polyphosphate accumulation organisms under short-term temperature conditions

蔡易玲(Yi-Ling Tsai)

指導教授 ： 蔡勇斌

國立暨南國際大學/科技學院/土木工程學系/碩士(2009年)

https://doi.org/10.6837/NCNU.2009.00083

摘要

本研究主要探討不同溫度條件下，重金屬鋅及濃度對活性污泥厭/好氧相釋/攝磷反應、PHAs合成/分解、乙醯輔酶A合成酶酵素活性、聚磷酸激酶酵素活性之影響，實驗進行以SRT 10天馴養達穩定之B-SBR系統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EBPR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合成/分解率及乙醯輔酶A合成酶酵素活性、聚磷酸激酶酵素活性等批次實驗，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不同重金屬鋅(Zn2+)、濃度(0∼4 mgl-1)之耐受性。結果顯示，未添加重金屬時微生物之比基質利用率、釋/攝磷率、PHAs合成/分解率、乙醯輔酶A合成酶酵素活性、聚磷酸激酶酵素活性，整體而言20℃環境下微生物對重金屬Zn2+之耐受性略高30℃者，而10℃時最差；另外，乙醯輔酶A合成酶受重金屬鋅抑制之抑制類型屬於混合型非競爭性抑制，而聚磷酸激酶酵素受重金屬鋅抑制之抑制類型屬於競爭型抑制，唯30℃時屬於反競爭型抑制。本研究亦發現污泥體內乙醯輔酶A合成酶酵素活性受重金屬毒性抑制時，造成微生物合成PHAs減緩，導致好氧環境無充足PHAs供攝磷之用，亦使釋磷率下降；再者好氧相水體存在之重金屬亦對聚磷酸激酶酵素活性具毒性抑制，此時微生物受體內碳源不足及外部毒性物質之影響，抑制代謝行為，進而惡化系統除磷效果；由此可知PHAs及乙醯輔酶A合成酶兩者於厭/好氧環境下之消長相互影響、牽制，而聚磷酸激酶酵素於好氧環境下更是直接影響攝磷率。

關鍵字

重金屬 ； 生物除磷 ； PHAs ； 乙醯輔酶A合成酶聚磷酸激酶

並列摘要

This study mainly investigated the effects of Zinc metal ion and concentration(0∼4mgl-1) on the phosphorus removal mechanisms , including phosphorus release/uptake, polyhydroxyalkanoates (PHAs) synthesis/degradation, and total intercellular Acetyl CoA Synthase activity and Polyphosphate Kinase activity of the activated sludge under short-term temperature condition. The performance of B-SBR activated sludge, which was acclimated until steady state basing on the condition of sludge retention time (SRT) 10 days , maintained the removal raties of COD and PO43- above 90 %.

In order to realize the operational strategy for EBPR system under metal invasion situation, the performances of batch experiments of phosphate release and uptake, PHAs synthesis/degradation, and total intercellular Acetyl CoA Synthase activity and Polyphosphate Kinase activity were used as indicators to investigate the effects of heavy metal zinc on phosphate removal mechanisms and toxic inhibition of microorganisms under different metal concentration (0∼4mgl-1) and temperature conditions(10℃∼30℃). In addition, inhibitory type about Acetyl CoA Synthase inhibited by zinc was mixed non-competitive inhibition, while the Polyphosphate Kinase inhibition type was competitive inhibition.

Results of batch experiments under the condition of without any metal addition showed that specific substrate utilization rate (SSUR), specific phosphorus release/uptake rates(SPRR,SPUR), PHAs synthesis/degradation rates, and total intercellular Acetyl CoA Synthase and Polyphosphate Kinase activities of microorganisms had the best tolerant ability to zinc invasion under 20℃, In addition , the temperature order of the tolerant ability of microorganisms to heavy metal invasion was 20℃＞30℃＞10℃,

It was also found in the study that, the microorganism intercellular Acetyl CoA Synthase Enzyme activity was inhibited by zinc metal toxicity, it resulted in microbial synthesis of PHAs slowed down and insufficient PHA and total intercellular Acetyl CoA Enzyme activity were provided for phosphorus uptake in aerobic stage , In addition, the existence of metal zinc also influenced the decomposition of PHAs in aerobic phase. At the same time, the phosphate removal ability was further deteriorated due to the insufficient of intercellular carbohydrate and external toxic inhibition. Thus, it could be known that the increase or decrease of PHAs and Acetyl CoA Synthase activity intercellular carbohydrate metabolism were influenced and impacted by each other in both anaerobic and aerobic phase, In the other hand, The Polyphosphate Kinase directly impacted on the phosphorus uptake in the aerobic phase.

並列關鍵字

heavy metals ； phosphate removal ； Acetyl CoA Synthase ； Polyphosphate Kinase

參考文獻

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