Effect of flocculation and/or adsorption as pretreatment on the critical flux of crossflow microfiltration

This study aims at identifying the effect of pretreatment such as flocculation and/or adsorption on the performance of crossflow microfiltration (CFMF). CFMF performance was studied in terms of critical flux. The results indicated that: (1) flocculation alone as a pretreatment could effectively remove the large molecular weight organic matter from 30,000 to 60,000 Daltons; (2) flocculation, together with adsorption as a pretreatment to CFMF, could remove both large and small molecular weight organics; (3) flocculation as a pretreatment was significantly better than adsorption in improving the critical flux; (4) critical flux increased from 100 L/m2.h to 520 L/m2.h when flocculation–adsorption was applied. The critical flux in long-term experiments was the same as that of the short-term experiments. However, the critical flux slightly decreased (5%) in long-term experiments compared to short-term operation with flocculation and adsorption as a pretreatment.

Flocculation with ferric chloride was efficient in removing large MW organic matter from 30,000 to 60,000 Daltons. It also could remove some of the small MW organic compounds due to the complexation mechanism. However, adsorption was not able to remove effectively the large MW organics (30,000–60,000 Daltons). When This research was funded by an Australian Research Council (ARC) Discovery grant.