Influence of Influent Composition on Membrane Fouling in Membrane Bioreactors
膜生物反应器中进水组成对膜污染的影响

Effect of influent 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 hydrophobicity of sludge flocs and membrane hydrophobicity increase, enhancing the hydrophobic 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.