强化除磷型膜生物反应器的膜污染特性

Study on Characteristics of Membrane Fouling in EBPR-MBR

采用强化除磷型膜生物反应器处理合成低浓度生活污水,考察其膜污染特性与机制。通过三维荧光光谱(EEM)对胞外聚合物(EPS)、溶解性微生物产物(SMP)及膜孔内部的溶解性污染物进行表征,并采用傅里叶红外光谱(FT-IR)对膜表面污染物质的官能团进行检测,发现多糖与蛋白质类物质是导致膜污染的主要因素;采用扫描电镜与能量色谱X射线光谱仪(SEM-EDX)对污染膜表面的监测表明,Ca、Mg、Al、Si、Fe等金属元素对膜表面无机污染及滤饼层的形成贡献较大。试验阶段好氧膜池污泥的EPS和SMP平均值分别为12.6、4.4 mg/gVSS,膜组件对TEPS中多糖和蛋白质的截留率分别为78.6%和91.2%。EPS与SVI有较好的线性相关性(R2=0.967 3),EPSp在TEPSp中的比例是决定污泥沉降性的关键因素。序批式修正污染指数(MFI)试验表明,当EPS、SMP、TEPS含量增加时,MFIsol、MFIss及TMFI呈增大趋势,污泥上清液MFIsol与悬浮固体的MFIss在TMFI中各占约50%,TMFI可以作为预测膜污染速率快慢的指标。

The enhanced biological phosphorus removal membrane bioreactor （EBPR-MBR） was utilized to treat synthetic low-strength domestic sewage, and the characteristics and mechanisms of membrane fouling were investigated. Extracellular polymeric substances （EPS） , soluble microbial products （SMP） and soluble foulants in membrane pores were characterized by three-dimensional fluorescence spectroscopy. Functional groups of foulants on the membrane surface were examined by Fourier transform infrared spectroscopy （FHR）. Results suggested that carbohydrates-like and protein-like substances were the causes to membrane fouling. The SEM/EDX analysis indicated that Ca, Mg, Al, Si, and Fe metal elements contributed to inorganic fouling and formation of cake layer. The values of EPS and SMP in the aerobic-membrane tank maintained at 12.6 mg/gVSS and 4.4 mg/gVSS on average, respectively. 78.6% of carbohydrates and 91.2% of protein-like substances from TEPS were rejected by the membrane module. SVI was found to have good linear correlation with EPS （R2 = 0. 967 3 ） , whereas the pro- portion of EPSp in TEPSp was a key factor in sludge settling. Sequencing batch modified fouling index （MFI） test showed that MFIsol, MFIss and TMFI increased as SMP, EPS and TEPS increased. MFIsoI and MFIss accounted for 50% of TMFI. TMFI can be served as an indicator for predicting the membrane fouling rate.