Recently, many efforts has been made to improve the potency of natural polymer-based flocculants in wastewater treatment. Graft copolymerization of magnetic cellulose and polyacrylamide (PAM-g-MagCell) were synthesized through microwave assisted technique with the aid of ceric-ion-induced as catalyst. Through varying the monomer, polysaccharide and mass of catalyst, five grades of PAM-g-MagCell were synthesized. The influences of these factors toward grafting percentage were investigate. The flocculation performance of PAM-g-MagCell was also studied in treating anaerobically-treated palm oil mill effluent (AnPOME). The grafting ratio suggested that the optimum conditions for graft copolymerization were composed of 0.25 g catalyst ceric ammonium nitrate and 4:1 mass ratio of acrylamide monomer to magnetic cellulose. The results found that under such optimum conditions, flocculation performance had improved, whereby, sampled wastewater coloration and suspended solid were significantly reduced by 50% and 65%, respectively.