间歇性投加Fe(Ⅱ)控制陶瓷膜MBR膜污染的机理分析

Mechanism of membrane fouling control of ceramic membrane bioreactor by intermittent Fe(Ⅱ)addition

以陶瓷膜膜生物反应器(MBR)为研究对象,考察了间歇性投加Fe(Ⅱ)对合成废水中营养物质的去除效果,并分析了膜污染的控制机理。当n_(Fe)∶n_(P)为2时,TP、TOC和TN的去除率最高,分别为99.2%、97.5%和87.2%,出水达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)中一级A标准;当nFe∶nP为1和2时,出水Fe浓度分别为0.14μmol/L和0.16μmol/L(达到中水回用标准),膜过滤时间由12 d分别延长至92 d和41 d(跨膜压差30 kPa)。间歇性投加Fe(Ⅱ)可增大污泥粒径及减少污泥混合液中有机物含量,从而提高体系的过滤性能,有效降低膜污染阻力并缓解膜污染;n_(Fe)∶n_(P)为1时,含Fe不可逆污染层的阻力较小,膜污染控制效果最好。

Ceramic membrane bioreactor(MBR)was taken as the subject of study,and the effect of intermittent Fe(Ⅱ)addition on nutrient removal in synthetic wastewater,as well as the mechanism of membrane fouling control was studied.The results show that when n_(Fe)∶n_(P)is 2,the removal rates of TP,TOC,and TN are the highest,which are 99.2%,97.5%,and 87.2%,respectively.The effluent meets the Grade A standard of“Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant”(GB 18918—2002).When n_(Fe)∶n_(P)is 1 and 2,the Fe concentration in the effluent is 0.14μmol/L and 0.16μmol/L,respectively(reaching the reuse standardof reclaimed water),and the membrane filtration time is extended from 12 d to 92 d and 41 d,respectively(transmembrane pressure of 30 kPa).Intermittent Fe(Ⅱ)addition can improve the filtration performance of the membrane system,effectively reduce membrane fouling resistance,and alleviate membrane fouling by increasing floc size and reducing the organic matter content in the mixed liquor.When nFe∶nP is 1,the resistance of the Fe-containing irreversible fouling layer is small,and the membrane fouling control effect is the best.