Microalgal removal with natural coagulants

Algal removal capacity via coagulation-flocculation with natural products was investigated in the laboratory using the jar-test technique. Traditional chemical coagulants such as aluminium sulphate may have negative impacts on human health. For this reason, a natural coagulant, Tanfloc, was tested for algal (Chlorella, Microcystis, Oocystis, Scenedesmus) removal from surface water. The jar-test method was used to identify the best Tanfloc conditions, including operating parameters such as coagulant dosage (1-25 mg.l(-1)), initial algal concentration (original -75 mu g.l(-1)), pH (5-9) or agitation time (10-60 min). Removal capacity was verified for water with high algal contamination, and pH was not an important factor in the removal efficiency for pH values less than 8. Up to 95% of all algae were removed from aqueous solutions. The water sources did not have a considerable influence on the process. Coagulation-flocculation equilibrium data can be represented by the Langmuir and Freundlich models.