Removal of Oocystis algae from freshwater by means of tannin-based coagulant

The tannin-based coagulant agent Acquapol C1 was tested for algae removal. This coagulant can be used in drinking water treatment and consists of a chemically modified tannin extract from Acacia mearnsii. Low coagulant doses reached high algae removal percentage, and operational conditions of neutral pH and room temperature allow up 80 % algae removal with 5 mg L-1 of coagulant. If compared with other natural or inorganic coagulants, Acquapol C1 is more efficient than aluminum sulfate, a classical metal salt for water clarification. Experiments also were carried out in a pilot plant installation which gives a similar efficiency as the discontinuous jar-test experiments for algae removal.