微絮凝-超滤联用工艺处理低温水膜污染的机理

Mechanism of Membrane Fouling During the Treatment of Low Temperature Water by Micro-flocculation-ultrafiltration Process

通过微絮凝-超滤联用工艺处理不同温度水样,研究了微絮凝过程中有机物的去除效果、形成絮体特性的差异以及温度的不同所造成超滤膜污染的主要机理。结果表明:微絮凝过程对低温水样的有机物去除率优于常温水样;尽管不同温度水样微絮凝过程中形成絮体的大小差异不大,但低温水样形成絮体的分型维数要明显小于常温水样,这说明低温水样形成的絮体结构更加疏松;不论是低温水样还是常温水样,滤饼层阻力都在造成膜污染的膜阻力因素中占主导地位,与常温水样相比,低温水样有较高的相对膜通量,说明低温水样形成的絮体造成的膜污染程度要比常温水样轻,这与低温条件下所形成絮体的特性密切相关。

The removal of organic matter,the floc properties and the main mechanism of membrane fouling resulting from different temperatures were investigated using microflocculation-ultrafiltration process in this study.Results showed that flocs formed in the lower temperature water sample had better removal efficiencies of nature organic matter.Though the floc size of flocs formed in different temperatures water samples had little difference,fractal dimension（dF）of the flocs formed in the low temperatures water sample was lower than normal temperatures water sample,indicating that flocs formed in the low temperatures water sample had a more loose interior floc structure.The cake layer was the main reason of membrane fouling regardless of the temperature of water sample.The lower temperature water sample with higher permeate flux had better performance in membrane fouling and this was closely related to the floc properties of flocs formed in low temperature.