Alum, FeCl3 and PAC removed relatively low amounts of COD. Alhamad et al. (2005) reported 46.6%, 52.9% and 48.1% of COD removal for 150 mg/L of Alum, FeCl3 and PAC, respectively. Amuda and Alade (2006) reported relatively high COD removal using alum. However, they used 750 mg/L of alum to achieve 75% COD removal in dyeing wastewater. Zheng et al. (2011) removed 73.5% of COD in domestic wastewater using 50 mg/L polymeric phosphate-aluminum chloride (PPAC). Mg-sericite was more effective at COD and BOD removal compared to alum and FeCl3. Compared to polymer flocculants, Mg-sericite required a higher dosage for COD removal; however, the removal effect was greater than that of polymer flocculants.