Evaluation of chitosan as a natural coagulant for drinking water treatment

Chitosan, a natural biopolymer, was evaluated for its ability to be used as a coagulant to treat water for potable use both in isolation and in combination with other water treatment technologies, specifically ion-exchange and activated carbon. Chitosan was found to be very effective for particle removal at doses far below those required for equivalent turbidity removal by inorganic coagulants. However in the water sources tested, chitosan was not particularly efficient for dissolved organic carbon (DOC) removal when applied as the sole treatment step. When applied as the final clarification stage of a multi-step treatment process, chitosan exhibited limited turbidity reduction due to specific flocculation requirements. This combination of treatment technologies was also unable to further reduce secondary water quality parameters, such as disinfectant demand and trihalomethane (THM) formation.