Effect of Physicochemical Variables on Algal Autoflotation

Combined chemical flocculation and autoflotation were examined using pilot scale process with chitosan and alum as flocculants. Positive correlation was observed between dissolved oxygen concentration and rise rate. Rise rate depended entirely on the autoflotation parameters: mixing intensity, retention time, and flocculant contact time. Also, rise rate was influenced by the type of flocculant used. The maximum rise rate with alum was observed to be 70 m/h, whereas that with chitosan was approximately 420 m/h. The efficiency of the flocculation-autoflotation process was superior to that of the flocculation-sedimentation process.