Chemical flocculation is considered to be a reliable and economical means for the harvesting of microalgae. Organic cationic polymers can induce efficient flocculation of freswater microalgae at low dosages (between 1 and 10 mg litre-1). However, the high salinity of the marine environment was found to inhibit flocculation with polyelectrolytes. This phenomenon was studied with three different cationic polymers. Inhibition of flocculation was diminished at reached salinity levels, and effective flocculation was attained at salinity levels lower than 5 g litre-1. The reduced effectiveness of cationic polymers to induce microalgae flocculation in sea and brackish water is primarily attributed to the effect of medium ionic strength on the configuration and dimension of the polymer, as indicated by changes in the intrinsic viscosity. At high ionic strength, the polymer shrinks to its smallest dimensions, and fails to bridge between algal cells.
ASJC Scopus subject areas
- Environmental Science (all)
- Engineering (all)
- Earth and Planetary Sciences (all)