Abstract:

The combined process, flocculation-ultrafiltration, has been applied to the treatment of the secondary effluent in an urban sewage treatment plant, using polymeric aluminum chloride (PAC) and ferric chloride(FeCl₃) as flocculents, respectively, the removal effect of the combined process on the organic matter investigated, and the threedimensional fluorescence characteristic of the organic matter analyzed. The fractal dimension of flocs and its influences on flux of ultrafiltration membrane have been discussed. The experimental results demonstrate that the flocculation pretreatment can enhance the removing rate of organic matter from the sewage by ultrafiltration, the removing rates of UV₂₅₄ and DOC by FeCl₃+UF can reach 62.1% and 79.6%, respectively, while the removing rates of UV₂₅₄ and DOC by PAC+UF can reach 68.6% and 85.4%, respectively. Moreover, the fractal dimension of flocs formed with PAC is smaller than that formed with FeCl₃. As a result, the flocs formed is looser and more propitious to slow down the descent speed of membrane flux.

Key words: flocculation, ultrafiltration, organic matter, membrane fouling

摘要：

分别以聚合氯化铝（PAC）、三氯化铁（FeCl₃）为絮凝剂，采用絮凝-超滤工艺处理城市污水厂二级出水，考察了絮凝-超滤联合工艺对污水中有机物的去除效果，分析了有机物的三维荧光特征，并探讨了絮体的分形维数及对超滤膜通量的影响。实验结果表明，絮凝预处理强化了超滤对污水中有机物的去除率，FeCl₃+UF对UV₂₅₄和DOC的去除率分别可达62.1%、79.6%，PAC+UF对UV₂₅₄和DOC的去除率分别可达68.6%、85.4%。PAC形成的絮体分形维数比FeCl₃要小，形成的絮体更加疏松，更有利于延缓膜通量的下降速度。

关键词: 絮凝, 超滤, 有机物, 膜污染

CLC Number: 

• X52

• X703