Effect of coagulation on fouling potential and removal of algal organic matter in ultrafiltration pretreatment to seawater reverse osmosis
Effect of coagulation on fouling potential and removal of algal organic matter in ultrafiltration pretreatment to seawater reverse osmosis
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DOI：
10.1016/j.watres.2014.04.001
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发表时间：
2014-08-01
期刊：
影响因子：
12.8
通讯作者：
Kennedy, Maria D.
中科院分区：
文献类型：
--
作者：
Tabatabai, S. Assiyeh Alizadeh;Schippers, Jan C.;Kennedy, Maria D.
研究了海水超滤系统中混凝对膜污染及藻类有机物去除的影响。采用三氯化铁对水华硅藻近缘角毛藻AOM进行不同混凝方式和条件下的混凝处理。采用改进的污染指数-超滤法（MFI-UF）研究了混凝对膜污染的影响。AOM的去除进行了研究，为三种不同的模式的凝聚，即，凝聚后沉淀，凝聚后沉淀和过滤通过0.45 μ m，和内联凝聚后过滤通过150 kDa的UF膜。采用液相色谱有机碳检测法测定AOM的去除率，并重点研究了生物聚合物对AOM的去除效果。AOM（作为生物聚合物）具有较高的结垢潜力，MFI-UF测定结果表明，AOM的结垢潜力与过滤通量密切相关。此外，在过滤过程中，在膜上形成的滤饼/凝胶层是相当可压缩的;表现为在较高的过滤通量下较高的污染可能性和在过滤测试中压力的非线性发展。在混凝剂剂量>1 mg Fe/L时，混凝的影响特别显著。混凝也大大降低了AOM结垢潜力的通量依赖性，导致在恒定通量下过滤试验中压力的线性发展。这归因于生物聚合物在沉淀的氢氧化铁上的吸附和Fe-生物聚合物聚集体的形成，使得氢氧化铁沉淀物的结垢特性占上风，AOM结垢特性减弱。在低混凝剂剂量下，在线混凝/超滤比其他两种混凝模式更有效地去除AOM。在高混凝剂投加量的情况下，清除絮凝物的条件占主导地位，AOM去除率相当高，并由混凝剂投加量而不是混凝模式控制。(C)2014由Elsevier Ltd.出版
This paper investigated the effect of coagulation on fouling potential and removal of algal organic matter (AOM) in seawater ultrafiltration (UF) systems. AOM harvested from a strain of bloom forming marine diatom, Chaetoceros affinis, was coagulated with ferric chloride under different coagulation modes and conditions. The effect of coagulation on fouling potential was determined with the Modified Fouling Index-Ultrafiltration (MFI-UF). Removal of AOM was studied for three different modes of coagulation, namely, coagulation followed by sedimentation, coagulation followed by sedimentation and filtration through 0.45 mu m, and inline coagulation followed by filtration through 150 kDa UF membranes. Liquid chromatography organic carbon detection was used to determine the removal of AOM with particular emphasis on biopolymers.AOM (as biopolymers) had a high fouling potential as measured by MFI-UF, which strongly depended on filtration flux. Moreover, the developed cake/gel layer on the membrane was fairly compressible during filtration; manifested as higher fouling potential at higher filtration flux and non-linear development of pressure in filtration tests.Coagulation substantially reduced fouling potential and compressibility of the AOM cake/gel layer. The impact of coagulation was particularly significant at coagulant doses >1 mg Fe/L. Coagulation also substantially reduced the flux-dependency of AOM fouling potential, resulting in linear development of pressure in filtration tests at constant flux. This was attributed to adsorption of biopolymers on precipitated iron hydroxide and formation of Fe-biopolymer aggregates, such that the fouling characteristics of iron hydroxide precipitates prevailed and AOM fouling characteristics diminished. At low coagulant dose, inline coagulation/UF was more effective in removing AOM than the other two coagulation modes tested. At high coagulant dose where sweep floc conditions prevailed, AOM removal was considerably higher and controlled by coagulant dose rather than coagulation mode. (C) 2014 Published by Elsevier Ltd.