Membrane fouling caused by lipopolysaccharides: A suggestion for alternative model polysaccharides for MBR fouling research
Membrane fouling caused by lipopolysaccharides: A suggestion for alternative model polysaccharides for MBR fouling research
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DOI：
10.1016/j.seppur.2019.04.059
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发表时间：
2019-09
影响因子：
8.6
通讯作者：
K. Kimura;T. Kakuda;H. Iwasaki
中科院分区：
文献类型：
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作者：
K. Kimura;T. Kakuda;H. Iwasaki
多糖是膜生物反应器（mbr）中的关键污染物。用于MBR污垢研究的多糖应代表真实的污垢，海藻酸盐和葡聚糖常被用作模型多糖。然而，它们的性质不一定与实际引起mbr膜污染的多糖相似。近年来的研究表明，在mbr中引起膜污染的多糖具有脂多糖（lps）的结构，脂多糖是革兰氏阴性菌细胞壁的成分。因此，在本研究中，研究了市售的低脂多糖引起的膜污染，并与模型多糖引起的膜污染进行了比较。在四种不同的微滤（MF）和超滤（UF）膜的批量过滤试验中，无论使用哪种膜，在相同有机碳浓度的条件下，低脂多糖的膜污染都比海藻酸盐或葡聚糖更严重。脂多糖的性质与海藻酸盐和葡聚糖有很大的不同。特别是，通过石英晶体微天平（QCM）质量测量评估的LPS对PVDF聚合物的亲和力非常高，这可能是LPS造成严重污染的原因。在模拟真实MBR中溶解多糖突然增加的模型多糖和生物质悬浮液混合物的过滤实验中，LPS诱导了显著的不可逆污染，而海藻酸盐和葡聚糖则没有。本研究的结果清楚地表明了脂多糖的高污染潜力。因此，建议在未来的MBR污染研究中使用LPSs。
Polysaccharides were identified as key foulants in membrane bioreactors (MBRs) in previous studies. Polysaccharides used for MBR fouling research should represent real foulants, and alginate and dextran have often been used as model polysaccharides. However, their properties are not necessarily similar to those of polysaccharides that actually cause membrane fouling in MBRs. In recent studies, it was shown that polysaccharides causing membrane fouling in MBRs had the structures of lipopolysaccharides (LPSs), which are components of the cell wall of gram-negative bacteria. In the present study, therefore, membrane fouling caused by commercially available LPSs was investigated and was compared with that caused by model polysaccharides. In a series of batch filtration tests using four different microfiltration (MF) and ultrafiltration (UF) membranes, regardless of the membrane used, LPSs caused more severe membrane fouling than did alginate or dextran when they were filtered under the condition of the same organic carbon concentration. The properties of LPSs were found to be considerably different from those of alginate and dextran. In particular, affinity of LPS to PVDF polymer assessed by quartz crystal microbalance (QCM) mass measurement was remarkably high, and it would account for the severe fouling caused by LPSs. In experiments with filtering of mixtures of the model polysaccharides and a biomass suspension collected from a pilot-scale MBR, which were conducted to mimic the sudden increase in dissolved polysaccharides in real MBRs, LPS induced significant irreversible fouling, while alginate and dextran did not. The results obtained in this study clearly demonstrated high fouling potential of LPSs. Use of LPSs in future MBR fouling studies is therefore recommended.