预涂覆膜重力流超滤工艺的过滤性能与滤饼层特性

Filtration Performance and Bio-cake Layer Characteristics of Pre-coated Gravity-driven Membrane(GDM)-based Drinking Water Process

重力流超滤(GDM)具有操作简单、能耗低、维护少等特点,但稳定膜通量较低、生物滤饼层性能仍需改善。针对GDM生物滤饼层对稳定膜通量作用的关键问题,构建了铝基絮体(ABF)预涂覆GDM(ABF-GDM)工艺,研究了其过滤性能和滤饼层特性,阐明了ABF预涂覆层对生物滤饼层特性的作用机制。ABF-GDM工艺的稳定膜通量为6.70 L/(m^(2)·h),比GDM提高了19.22%;滤饼层阻力和膜孔阻力分别为2.11×10^(12)m^(-1)和1.99×10^(11)m^(-1),比GDM降低了21.60%和19.37%;稳定阶段对溶解性有机碳和氨氮的平均去除率分别为22.10%和89.81%,比GDM提高了7.48%和5.92%。ABF预涂覆滤饼层可明显提高GDM生物滤饼层的粗糙度和多孔性,并降低胞外聚合物(EPS)含量,其中ABF-GDM的表面孔隙率达34.24%,比GDM高31.22%;EPS中蛋白质和多糖含量分别为723.40、1013.18 mg/m^(2),分别比GDM降低22.17%和31.92%。ABF预涂覆层可改变生物滤饼层的微生物群落结构,其中关键菌属的相对丰度变化可直接影响生物滤饼层的形貌结构和生化组分,使得ABF-GDM的滤饼层粗糙多孔性增加、EPS含量降低、稳定膜通量提高。

Gravity-driven membrane(GDM)process has the characteristics of easy operation,low energy consumption,and less maintenance.However,the stable flux is low and the performance of the bio-cake layer still needs to be improved.In this study,focusing on the key issue of the effect of GDM bio-cake layer on stable flux,the Al-based floc(ABF)pre-coated GDM(ABF-GDM)process was constructed.The membrane filtration and bio-cake layer characteristics of the ABF-GDM process were studied,and the mechanism of effect of ABF pre-coated layer on the characteristics of bio-cake layer was elucidated.The results showed that the stable flux of ABF-GDM was 6.70 L/(m~2·h),which was 19.22%higher than that of GDM;the cake layer resistance and pore blocking resistance were 2.11×10~(12)m~(-1)and 1.99×10~(11)m~(-1),respectively,which were 21.60%and 19.37%lower than that of GDM.The average removal rates of dissolved organic carbon and ammonia nitrogen at the stable stage were 22.10%and89.81%,respectively,which were 7.48%and 5.92%higher than that of GDM.The ABF pre-coated cake layer could significantly improve the roughness and porosity of the GDM bio-cake layer,and reduce the EPS content.The surface porosity of ABF-GDM was 34.24%,which was 31.22%higher than that of GDM.The contents of protein and polysaccharide of EPS were 723.40 mg/m~2 and 1013.18 mg/m~2,respectively,which were 22.17%and 31.92%lower than that of GDM,respectively.The ABF pre-coated layer could change the microbial community structure in the bio-cake layer,and the relative abundance of keystone taxa could directly affect the morphology structure and biochemical components of the bio-cake layer,resulting in the increase of the roughness and porosity of the ABF-GDM bio-cake layer,the decrease in EPS content,and an increase in stable flux.