膜生物反应器中新型无纺布膜过滤特性及膜污染特征
Filtration performance and fouling characteristics of novel nonwoven membrane in membrane bioreactors
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摘要: 通过无纺布和聚偏氟乙烯平板膜组件在相同操作条件下的对比实验,研究无纺布膜的过滤特性。结果表明,2种膜的膜生物反应器COD、氨氮平均去除率均>90%。过膜压力变化表明在长期运行条件下,无纺布可适于作为膜生物反应器的过滤介质,其过滤机理为膜表面滤饼层形成动态膜,从而增强了膜截留能力。膜污染研究表明,无纺布膜阻力主要来自滤饼层(占总阻力的83.6%),经清洗后膜通量可恢复至94%。扫描电镜显示膜表面滤饼层较厚,结合膜阻力分析结果认为,该滤饼层对膜污染和可逆性影响较大。对膜表面和膜孔中胞外聚合物(EPS)的红外分析证实,其中含有蛋白质和多糖物质,而且组分分析表明蛋白质是膜污染物EPS中的主要组分,在膜孔中的含量比滤饼层中还高。Abstract: The membrane filtration property of nonwoven material in submerged MBR(membrane bioreactor) system was investigated by comparing with a PVDF(polyvinylidene fluoride) flat membrane under the same conditions. The results showed that after filtering through the two membrane modules, an average COD and NH+4-N removal of effluent reached over 90%. The changes of TMP(Transmembrane pressure) revealed that the nonwoven materials acted better for filtration in membrane bioreactor system under long-term operation. The filtration mechanism of nonwoven module was attributed to the dynamic membrane filtration by the cake layer formed on the nonwoven surface, which reinforced the interception of the membrane. The analysis of membrane resistance in nonwoven module showed that the cake layer resistance predominated and amounted to 83.6% of the total resistance. 94 % of the original flux of membrane was restored after chemical washing. The chemical analysis and FT-IR analysis proved that the protein are the main contaminants in EPS (extracellular polymeric substance) in fouled membrane, its contents are much higher than polysaccharide molecules in cake layer and within the membrane. SEM images showed that contaminants were mainly concentrated on the surface of nonwoven material, which contributed to the reversibility of fouling considering the result of the membrane resistance analysis.
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Key words:
- nonwoven material /
- PVDF membrane /
- membrane resistance analysis /
- EPS
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