【摘要】 在膜生物反应器中,活性污泥在膜表面沉积形成滤饼层是造成膜污染的主要因素。采用扫描电镜和自动图像分析技术研究了膜过滤滤饼层的微观结构,并以分形理论和Darcy定律为基础,推导出用于预测膜污染滤饼层渗透性能的数学模型,验证了该渗透模型的可靠性,并利用该渗透模型进行了膜生物反应器中污泥浓度对滤饼层渗透性能影响的研究。结果表明,活性污泥颗粒沉积形成的柔性滤饼层具有明显的多孔结构,并且具有很好的分形特征;膜污染滤饼层的分形维数能够真实反映滤饼层的孔隙率大小;用该渗透模型得到的渗透系数K′可以作为有效预测滤饼层渗透性能的参数;滤饼层渗透系数K′随污泥浓度的增大而递减,污泥浓度低于10000mg·L-1时,K′的变化趋势较小,污泥浓度达到10000mg·L-1以上时,K′急剧下降。更多还原

【Abstract】 The formation of fouling cake layer on the membrane surface is the major problem that hinders the practical application of membrane bioreactor (MBR) systems. In order to investigate the micro-mechanism of membrane fouling, the microscope and auto image analyzer were used to analyze the cake layer micro-structure. Based on the fractal theory and Darcy’s law, a new model used to evaluate the cake layer permeability for microfiltration of activated sludge wastewater was developed. The reliability of the model proposed and the effect of the mixed liquid suspended solids (MLSS) concentration on cake layer permeability were studied systematically. Results show that the cake layer is a typical fractal structure, and the fractal dimension has a linear relationship with the porosity of the fouling layer. The permeation factor of the fouling layer has a close relationship with specific resistance, which indicates that the permeation model proposed is a useful tool for studying the micro-mechanism of membrane fouling. There is some correlation between MLSS concentration and cake layer permeability, which is that the cake layer permeation decreases slightly or distinctly with the increase of the MLSS concentration when the MLSS concentration is lower or higher than 10,000 mg·L-1, separately.更多还原