ABSTRACT
Metal coagulants, especially Fe(III), are a more attractive option for Dutch water treatment circumstances than alum. Enhanced treatment options including e.g. the use of polyelectrolytes and/or algae conditioners should also be evaluated. The surface charge effects confirm the important role of well destabilised floc material for improved particle-bubble attachment and hence efficient dissolved air flotation (DAF). The study proved that cationic polyelectrolytes can offer an efficient and reliable option for DAF. Ozone conditioning of model water and DAF, combined with metal coagulant application, metal coagulant plus cationic polyelectrolyte coagulant aid, and cationic polyelectrolyte coagulant, all outperformed the treatment option with metal coagulant only. Increase of the larger particle size fraction at the expense of the smaller one was essential for efficient DAF.
