The use of natural organic flocculants for harvesting microalgae grown in municipal wastewater at different culture densities

Harvesting microalgae from liquid culture is a difficult issue to solve and most commonly done through settling. However, settling slow process on its own generally needs be induced chemically or by introducing stress the culture. Polymeric, cationic substances, such as cationised starch chitosan, are often used for flocculation These large, positively charged molecules form large clusters with suspended particles in medium. In present study, three natural organic flocculants (cationic starch, chitosan acacia tannin S5T) were tested harvest microalgal cultures grown wastewater. Two species, one strain of Chlorella vulgaris Scenedesmus obliquus, cultured municipal wastewater different lengths time, settled using either S5T. Results indicated that S5T worked approximately same efficiency two assayed although it requires relatively high dosage function (about 300 mg L−1), while other varied species species.