在生物反應器中利用氧化鐵(-Fe2O3) 顆粒減少薄膜積垢

薄膜生物反應器(Membrane bioreactor, MBR)已被積極地應用於都市和工業廢水處理上，基於其優良的分離能力和良好的出水水質。然而，其薄膜積垢仍是此程序中主要問題之一，其缺點導致薄膜操作通量及跨膜壓力(transmembrane pressure, TMP)的性能降低。在此研究中，磁赤鐵礦已被用來作為積垢減緩劑，以減少在薄膜生物反應器的積垢。多孔性磁赤鐵礦 (Maghemite, -Fe2O3) 的尺寸為微型粉末 (~500 nm)、BET表面積為38.79 m2/g、孔隙體積為0.14 cm3/g、孔隙尺寸為25.02 nm藉由簡單水熱法製備以減少蛋白質引起的積垢。磁赤鐵礦對於牛血清蛋白 (bovine serum albumin, BSA)最大吸附量達30.01 mg/g。小表面積的磁赤鐵礦和磁赤鐵礦與牛血清蛋白分子之間的靜電斥力可能限制吸附能力。並有研究發現磁赤鐵礦應用於實驗室規模反應器，透過蛋白質減緩商業聚偏二氟乙烯(Poly(vinylidene fluoride), PVDF)薄膜的積垢。磁赤鐵礦顆粒的效率會依從機械混合液體剪切強度改變：在低攪拌速率，磁赤鐵礦增加薄膜的輸出性與滲透性，違背了較高攪拌速率的結果。攪拌速率在50 rpm是有最佳緩和效果。在最佳條件下，磁赤鐵礦改善了薄膜過濾的性能，並證實其積垢減緩劑的有效性。此外，兩平行薄膜生物反應器操作以驗證磁赤鐵礦添加於薄膜積垢的效果，其中針對都市廢水處理添加0.54 gL-1的磁赤鐵礦進行討論。結果顯示磁赤鐵礦的應用在薄膜生物反應器中能有效減少胞外聚合物(extracellular polymeric substances, EPS)的含量。出流水中COD的範圍從12 – 55 mg/L其平均COD去除率為95%。兩個薄膜生物反應器的出流水濁度值介於0.4 – 1.5 NTU。兩個薄膜生物反應器中進料和操作條件是相似的，其COD、濁度、TMP、流率、SVI、MLSS及EPS分別監測超過60天。磁赤鐵礦添加於薄膜生物反應器的效果指出在0.54 gL-1磁赤鐵礦劑量在薄膜生物反應器中減少薄膜積垢

關鍵字

磁赤鐵礦(-Fe2O3) ；吸附作用；聚偏二氟乙烯；剪切強度；薄膜生物反應器；薄膜積垢；胞外聚合物

並列摘要

Membrane bioreactor (MBR) have been actively employed for municipal and industrial wastewater treatments because of its excellent separation ability and production of good effluent quality. However, membrane fouling remains a major drawback of this process because it deteriorates the membrane performance with regard to operational flux and transmembrane pressure (TMP). In this study, maghemite has been used as a foulant reducer to reduce fouling in membrane bioreactor. Maghemite (-Fe2O3) with porous micro sized powder (~500nm), BET surface area 38.79 m2/g, pore volume 0.14 cm3/g and pore size 25.02 nm was prepared by simple hydrothermal method in order to reduce protein-induced fouling. Maghemite attained maximum adsorption of 30.01 mg/g for bovine serum albumin (BSA). The small surface area of maghemite and electrostatic repulsion between maghemite and BSA molecules probably limited the adsorption capacity. It was found that the application of maghemite to a laboratory-scale reactor mitigated the fouling of commercial poly(vinylidene fluoride) PVDF membrane by protein. The efficiency of the maghemite particles was reliant on liquid shear intensity from mechanical mixing: At low stirring rates maghemite increased membrane output and permeability, contrary to the results of higher stirring rates. The optimum mitigation effect was found at stirring rate 50 rpm. In favorable condition, maghemite improved the performance of the membrane filtering proving its effectiveness as foulant reducer. Furthermore, two parallel membrane bioreactors (MBR) were operated to verify the effect of maghemite addition on membrane fouling for municipal wastewater treatment at maghemite addition of 0.54 gL-1. The results showed that the application of maghemite was effective in decreasing the content of extracellular polymeric substances (EPS) in MBR at maghemite dosage of 0.54 gL-1. The average COD removal was 95% resulting in an effluent with COD ranging from 12-55 mg/L. The turbidity of both MBR effluent values ranged from 0.4 to 1.5 NTU. The feed and operating conditions were similar in both MBR, and COD, turbidity, TMP, flow rate, SVI, MLSS and EPS were monitored over 60-day period. Detailed studies on the effect of maghemite addition in MBR indicated that maghemite dosage of 0.54 gL-1 was able to reduce fouling in membrane bioreactors.

並列關鍵字

Maghemite(-Fe2O3) ； adsorption ； PVDF (poly-vinylidene fluoride) ； shear intensity ； MBR (membrane bioreactor) ； membrane fouling ； EPS (extracelluler polymeric substance).

參考文獻

[1] S. Judd, C. Judd, The MBR Book: Principles and Applications of Membrane Bioreactors in Water and Wastewater Treatment 1st ed., Elsevier, Oxford, 2006.

[2] Atkinson, Research studies strong growth for MBR markets, Membrane

Graaf, T. Wintgens, Membrane bioreactor technology for wastewater treatment

and reuse,Desalination, 187 (2006) 271-282.

[4]A.Drews,Membrane fouling in membrane bioreactors-Characterisation, contradictions, cause and cures, Journal of Membrane Science, 363 (2010) 1-28.

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在生物反應器中利用氧化鐵(-Fe2O3) 顆粒減少薄膜積垢

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