The efficiency of chitosan as a coagulant in the treatment of the effluents from the Sugar Industry

Abstract

Chitosan has been used as a coagulant for industrial wastewater treatment. However, no attention has been given to the coagulation of sugar effluents using this polymer. Two effluent streams from a local sugar refinery, namely the final effluent (FE) and the resin effluent (RE) were treated using chitosan prepared by dissolution in aqueous hydrochloric acid. The optimum chitosan dosage was found to be 138 mg/l and 7.41 mg/l for RE and FE respectively, beyond which, the efficiency of the coagulant decreased. The efficiency of the chitosan was higher under acidic conditions and using sodium hydroxide to adjust the pH negatively affected the performance of the chitosan. The treatment of FE yielded better removal efficiency (97% total suspended solids, 61% colour and 35% chemical oxygen demand) than RE (68% total suspended solids, 30% colour and 15% chemical oxygen demand). This coagulant can be used to pre-treat turbid water for further treatment.