不同污泥停留時間對薄膜生物反應槽中兩種薄膜阻塞機制與積垢物之分析

Effect of Sludge Retention Time on Membrane Fouling through Identification of Fouling Mechanism and Foulant in MBR

劉馥萱(Fu-Hsuan Liu)

中原大學/工學院/土木工程研究所/碩士(2011年)

https://doi.org/10.6840/cycu201100836

摘要

許多文獻均指出薄膜積垢主要是由胞外聚合物(Extracellular Polymeric Substances,EPS)所導致。本實驗操作三個不同SRT(SRT為5、15、30天)的薄膜反應槽並於反應槽內置入兩種不同薄膜(PTFE、PVDF)，以三種不同的萃取方法(甲醛-氫氧化鈉法、甲醛-氫氧化鈉-超音波法與陽離子交換樹脂)萃取污泥與薄膜上的積垢物，並且測量兩種薄膜上的阻抗值分布，以期瞭解薄膜積垢物形成機制與積垢物的組成。實驗結果指出，甲醛-氫氧化鈉法為最高萃取率，其次於三個不同SRT中以SRT為5天所產生的EPS含量最多，導致薄膜積垢率最為嚴重；而EPS內的組成以蛋白質大於碳水化合物大於腐植酸。在薄膜表面上PVDF的阻抗值高於PTFE，因為薄膜結構的不同導致薄膜阻抗值分布也不同。薄膜積垢物的總組成含量於PTFE與PVDF相近，因為都於同一壓力下進行洗膜，所以累積物質的含量接近；而薄膜積垢物組成以蛋白質與碳水化合物為主，蛋白質因為分子量大累積於膜表面上且相對疏水性高導致薄膜疏水性上升，碳水化合物則是分子量小阻塞於膜孔洞內部且碳水化合物的官能基使薄膜去親水化，蛋白質與碳水化合物造成薄膜積垢率上升。薄膜積垢率隨操作時間增長有成正比成長的趨勢，而積垢率上升的速率則是取決於SRT的長短，SRT的條件改變會影響污泥的結構與特性，短SRT中EPS含量增加導致積垢率上升。

關鍵字

薄膜生物反應槽 ； 污泥停留時間 ； 薄膜積垢 ； 胞外聚合物

並列摘要

Many literatures indicate that the membrane fouling is mainly constituted of Extracellular Polymeric Substances(EPS). In this study, the membrane bioreactor was operated at three different SRT(5, 15, 30day). Two types of membrane (PTFE
＆PVDF ) were used and placed inside the MBR. Three extraction methods were adopted to extract the EPS from the sludge and fouling on the membrane surface. They were Formaldehyde-NaOH, Formaldehyde-NaOH-Sonication and cation-exchange resin. The results showed that the extraction rate of Formaldehyde-NaOH was the highest and the highest amount of extracted EPS occurred when SRT was 5day compared to the other two SRT, consequently leading to a severe membrane fouling. In the composition of EPS, the protein is more than carbohydrate in proportion, and carbohydrate more than humic acid. On the membrane surface, the specific resistance of PVDF was superior to that of PTFE due to the different membrane structure. The composition of membrane fouling for both PTFE and PVDF was similar because the same pressure was applied for membrane cleaning. In addition, the membrane fouling was mostly composed of proteins and carbohydrate. Because of its high molecular weight, Protein directly deposited on the membrane surface and had relatively high hydrophobicity, which contributed to the increase of membrane hydrophobicity; however, due to the small molecular weight of carbohydrate, it deposited within the pore, and the functional groups in carbohydrate all worked together to decrease the hydrophilicity of membrane. Therefore, proteins and carbohydrate would lead to the mounting of membrane fouling. Membrane fouling was positively proportional to the extension of the operation time. The velocity of membrane fouling was dependent on the SRT. The change of SRT might have the influence on the structure and property of sludge. In short SRT, the increase in the amount of EPS would result in the increase of membrane fouling rate.

並列關鍵字

Membrane bioreactor(MBR) ； Sludge Retention Time(SRT)

參考文獻

李晏齊，游勝傑(2008)薄膜阻塞機制與胞外聚合物之探討。中原大學土木所生物環境工程組。

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Barker, D.J. and Stuckey, D.C. (1999) A review of soluble microbial products (SMP) in wastewater treatment systems. Water Res 33 (14), 3063–3082.

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