超滤的预处理工艺对比研究:化学混凝与电絮凝

对比研究了化学混凝(chemical coagulation,CC)与电絮凝(electrocoagulation,EC)作为超滤膜分离的预处理工艺,在死端过滤条件下与超滤膜的作用机制以及对膜污染的减缓效果.主要研究了Al3+投加量对膜通量、絮体性质(粒径、强度系数、恢复系数、分形维数)、以及滤饼层性质的影响.结果表明,EC作为预处理时,生成的絮体强度大且结构紧实,在膜表面堆积形成的滤饼层具有疏松多孔、亲水性强的性质;而CC作为预处理时,生成的絮体强度低且比较松散,在膜过滤过程中容易被压力压碎压实,导致滤饼层比较密实、亲水性低.因此,EC作为预处理工艺对膜污染的减缓效果好,在运行过程中可以保持较高的膜通量,膜通量较CC高约5.57%.

Comparative Study on Pretreatment Process of Ultrafiltration: Chemical Coagulation and Electrocoagulation

The ultrafiltration membrane response mechanism and the effect on the membrane fouling under dead end filtration were comparatively investigated in ultrafiltration pretreatment processes using chemical coagulation (CC) and electrocoagulation (EC). The effects of Al³⁺ dosage on the flux of the membrane,the properties of the floc (particle size, strength coefficient, recovery coefficient, fractal dimension) and the properties of the cake layer were studied. The results showed that taking EC as a pretreatment method, the flocs were stronger and more compact, the cake layer deposited on the surface was porous and higly hydrophilic; while in CC pretreatment, the flocs were loose and had low strength, which would be compacted and crushed easily by the pressure in membrane filtration process, resulting in relatively dense cake layer and low hydrophilicity. Therefore, EC was the most effective pretreatment process to alleviate membrane fouling during operation, which could maintain a flux that was about 5.57% higher than CC.