膜生物反应器中进水组成对膜污染的影响

Influence of Influent Composition on Membrane Fouling in Membrane Bioreactors

研究了膜生物反应器中进水组成对膜污染的影响.结果表明,相对于正常组成来说进水中限氮或限磷引起的膜污染程度更重,尤以进水中限氮时更为严重.系统缺氮或缺磷时,污泥絮体的相对憎水性和膜的憎水性增加,使得膜和污泥之间的憎水相互作用增强,加速了污染物在膜表面的沉积和/或吸附.另外,进水中限氮或限磷时,污泥中丝状菌的数量增加,把颗粒污泥捆扎、束缚在其立体网状结构中,滤层结构更加致密,孔隙度减小,增加了膜污染阻力;丝状菌的作用还在于它们能够将污染物牢牢地缠绕、固定在膜表面,加强了膜表面污染物抵御曝气的水力冲刷作用的能力,从而也加速了膜污染.

Effect of in-fluent composition on membrane fouling in membrane bioreactors was investigated. Experiment results show that nitrogen deficiency or phosphorus deficiency influent can cause severer membrane fouling than normal influent, especially for the nitrogen deficiency. When the system lacks nitrogen or phosphorus, both the relative hydrophohicity of sludge floes and membrane hydrophohicity increase, enhancing the hydrophohic interactions between the membrane and sludge and thus accelerating the deposition and/or adsorption of foulants on membrane surface. In addition, in the case of nitrogen deficiency or phosphorus deficiency, the number of filamentous bacteria in sludge rises, which bind and fix particle sludge to their three-dimensional meshwork, leading to more compact cake layer with lower porosity and thus greater fouling resistance. Filamentous bacteria also strengthen the attachment of foulants on membrane surface to resist the scour of aeration, accelerating membrane fouling.