An algal removal using a combination of flocculation and flotation processes.

The paper describes certain facets of the removal of the algae (Scenedesmus quadricauda) from water, using a froth flotation separation method, in conjunction with two types of surfactants, (cetyltrimethylammonium bromide) CTAB and (sodium dodecylsulfate) SDS. A 90% algal removal efficiency was achieved when 100 mg l(-1) of CTAB was used whereas for the SDS solutions, the same concentration gave, by comparison, a very poor algal removal efficiency. An addition of 1 mg l(-1) of a commercial cationic polyelectrolyte, which was the optimal concentration as was evident from the zeta potential and the particle size distribution measurements, prior to the SDS addition resulted in a formation of algal flocs and consequently a substantial improvement in the extent of the algal removal.

Removal of algae using froth flotation.

This paper describes the removal of algae and attached water using a froth flotation method as a function of the collector type, aeration rates, the pH of the algal suspension and temperature of operation. Dispersed air flotation was used in this study to remove Scenedesmus quadricaudo. The addition of surfactants such as cetyltrimethylammonium bromide and sodium dodecylsulfate increased the aeration rates and reduced the size of air bubbles.