無機性混凝劑與生物程序放流水影響薄膜積垢指標之研究

Effects of Inorganic Coagulants and Biological Process Effluent on Membrane Fouling Index

孫志仁(Chih-Jen Sun)

指導教授 ： 莊順興

朝陽科技大學/理工學院/環境工程與管理系/碩士(2014年)

摘要

全球面臨水資源逐漸缺乏與開發不易及水資源受到污染之問題，因此水資源再利用已成為各國重視及探討的重要議題之一，而在水質淨化等技術中，薄膜技術最具有研究潛力。一般常見判斷薄膜阻塞之情形的參數包括污泥密度指數 (Silt Density Index, SDI)、修正積垢指數 (Modified Fouling Index, MFI) 及微阻塞指數 (Mini Plugging Factor Index, MPFI)。
污水處理廠常在生物處理使用混凝處理以增加顆粒或膠體污染物之去除效果，然而混凝處理後殘留的混凝劑所造成薄膜積垢之程度明顯影響放流水之回收再利用，則是另一值得探討之重點。
本研究將研發新的薄膜積垢指標，以便建立與實際面更為切合實際的應用指標，並且探討其中最佳的操作條件以及針對常用之混凝劑PACl、Al2(SO4)3 、FeCl3、FeSO4及生物處理程序放流水進行其對積垢指標之影響，期能掌握混凝劑操作濃度，有效預防薄膜積垢。
研究顯示，混凝劑Al2(SO4)3、PACl、FeSO4及FeCl3經垂直式過濾裝置與掃流式過濾裝置於SDI、MFI及SCFI之積垢特性，SDI及SCFI無法完全區別混凝劑之積垢特性，以MFI指標最能代表混凝劑於薄膜上之積垢特性。混凝劑Al2(SO4)3、PACl、FeSO4及FeCl3經垂直式過濾裝置與掃流式過濾裝置於SDI、MFI及SCFI三種指標下，其對薄膜之積垢程度為PACl>FeCl3>Al(SO4)3>FeSO4。
SBR放流水經垂直式過濾裝置與掃流式過濾裝置於SDI、MFI及SCFI之積垢特性，SDI、MFI及SCFI三種積垢指標皆能區別SBR放流水於不同稀釋倍數下對薄膜之積垢特性，而使用UF程序作前處理，其降低薄膜積垢之效果有限，其原因在於放流水中有機物濃度及UF孔徑及材質影響UF處理效果。
壓力及壓差對掃流式積垢指標之影響，以SDI、MFI及SCFI三種積垢指標於掃流式過濾裝置之最佳操作壓力建議設定在3.5~4.0 bar最佳操作壓差建議設定在5~10 psi。薄膜種類對垂直式及掃流式薄膜積垢指標之影響，綜合比較三種不同積垢指標SDI、MFI及SCFI下，MCE膜及PVDF膜二種薄膜材質在混凝劑Al2(SO4)3、PACl、FeSO4及FeCl3不同濃度下皆無明顯之差異。
以SDI、MFI、SCFI及過濾比阻，比較掃流式過濾裝置及垂直式過濾裝置之間的特性差異，以掃流式過濾裝置為最佳操作裝置。

關鍵字：薄膜積垢指標、污泥密度指數、修正阻塞指數、微阻塞指數、
垂直式過濾、掃流式過濾、混凝劑。

關鍵字

垂直式過濾 ； 微阻塞指數 ； 修正阻塞指數 ； 污泥密度指數 ； 薄膜積垢指標 ； 掃流式過濾 ； 混凝劑

並列摘要

Facing the global water resource shortage issues, many countries pays more attention on water reuse issue. In water purification technologies, membrane possesses show the most valuable potential. The parameters for judging membrane plugging situations include SDI (Silt Density Index), MFI (Modified Fouling Index) and MPFI (Mini Plugging Factor Index).
The sewage treatment plants often coagulate the secondary effluent to increase the pollutant removal . Using coagulant in the coagulation treatment can remove the colloidal components in water effectively, but the degree of membrane fouling resulted from the residual coagulant is another point deserving discussion.
This study developed new membrane fouling indicators, so as to establish more practical application indicators, and the optimum operating conditions and the influence of common coagulants PACl, Al2(SO4)3, FeCl3 and FeSO4 and the effluent of biological treatment process on the membrane fouling indicators are discussed.
The findings showed that the membrane fouling characteristics of coagulants Al2(SO4)3, PACl, FeSO4 and FeCl3 through vertical filter unit and crossflow filter unit in SDI, MFI and SCFI, SDI and SCFI cannot be distinguished completely. The MFI indicator represents the fouling characteristics of coagulant on the membrane best. In the SDI, MFI and SCFI indicators of coagulants Al2(SO4)3, PACl, FeSO4 and FeCl3 through vertical filter unit and crossflow filter unit, the fouling degree of membrane is PACl>FeCl3>Al(SO4)3>FeSO4.
In terms of fouling characteristics of SBR effluent through vertical filter unit and crossflow filter unit in SDI, MFI and SCFI, the SDI, MFI and SCFI membrane indicators can distinguish the fouling on membrane of SBR effluent at different extension rates. The UF procedure for pretreatment has limited effect on reducing the membrane fouling, because the organic concentration in the effluent and the UF pore size and material influence the UF treatment effect.
In terms of the influence of pressure and pressure difference on the crossflow fouling indicator, the optimum operating pressure of SDI, MFI and SCFI indicators for crossflow filter unit is recommended as 3.5~4.0 bar, the optimum operating pressure difference is recommended as 5~10 psi. In terms of the influence of membrane type on vertical and crossflow membrane fouling indicators, according to comprehensive comparison among the SDI, MFI and SCFI there is no obvious difference in the MCE film and PVDF film at different concentrations of coagulants Al2(SO4)3, PACl, FeSO4 and FeCl3.
The SDI, MFI, SCFI and specific filtration resistance are used to determine the characteristic differences between crossflow filter unit and vertical filter unit, the crossflow filter unit is the optimum operating device.

Keywords：Membrane Fouling Index, Silt Density Index, Modified Fouling Index, Mini Plugging Factor Index, Dead-End Filtration, Cross-Flow Filtration, Coagulants.

並列關鍵字

Dead-End Filtration ； Mini Plugging Factor Index ； Modified Fouling Index ； Silt Density Index ； Membrane Fouling Index ； Cross-Flow Filtration ； Coagulants

參考文獻

1. Allison, R.P., “Electrodialysis reversal in water reuse applications” ,

Desalination, 103(1-2), 11-18(1995)

3. Bae, T.H., Tak, T.M., “Interpretation of fouling characteristics of ultrafiltration membranes during the filtration of membrane bioreactor mixed liquor” , J. Membr. Sci, 264, 151-160(2005)

4. Barker, D. J., and D. C. Stuckey, “A review of soluble microbial products (SMP) in wastewater treatment systems”, Water Research, 33, pp. 3063-3082,(1999)

5. Benschoten, J. E. and Edzwald, J.K.“Chemical Aspects ofCoagulation Using Aluminum Salts-I. Hydrolytic Reactions of Alum and Polyaluminum Chloride” , Wat. Res., Vol.24, No.12, pp.1519-1526(1990)