Experimental study on chitosan composite flocculant for treating papermaking wastewater

k]In this study, the coagulating effect of a novel composite flocculant on treating papermaking wastewater was studied and discussed. Results indicated that it achieved the best coagulating effect when this composite flocculant consisting of 60 mg/l of polymerized ferrous sulfate, 2 mg/l of polyacrylamide and 0.4 mg/l of chitosan, and pH value of wastewater was adjusted to 7.5. It also observed that the removal rate of COD and SS with this novel composite flocculant reached 72.5% and 98.5% respectively. Compared with the conventional flocculant such as polyacrylamide/polyaluminium chloride, the percentage of removing COD and SS using this composite flocculant were increased by 15.2% and 6.4% respectively, moreover, its input cost was cut down by 18.4%. So this composite flocculant has significantly environmental and economic benefits.