Separation of algal cells from water by column flotation

The dispersed air flotation (DiAF) process was utilized to separate algal c ells (Chlorella sp.) from water. Two types of collector, cationic N-cetyl-N ,N,N-trimethylammonium bromide (CTAB) and anionic sodium dodecylsulfate (SD S), were used. It was observed that 20% of cell removal was achieved in the presence of 40 mg/L of SDS, and ca. 86% of the cells were removed at 40 mg /L of CTAB. Upon the addition of 10 mg/L of chitosan, over 90% of the cells were removed when SDS (20 mg/L) was used as the collector. Air flow rate a ffected cell flotation sightly. Optimum pH values for cell flotation were f rom 4.0 to 5.0. Flotation efficiency decreased at high ionic strength. The electrostatic interaction between collector and cell surface plays a critic al role in the separation processes.