Flocculation of low algae concentration water using polydiallyldimethylammonium chloride coupled with polysilicate aluminum ferrite.

The combined application of polydiallyldimethylammonium chloride (PDADMAC) and polysilicate aluminum ferrite (PSFA) was investigated to treat low algae density water samples, in which Microcystis aeruginosa is one of the dominant species. coagulation performance of M. aeruginosa was studied with regard to algal removal, Algal density was evaluated by determining the change in the optical density of the algal culture suspension at 680 nm and chlorophyll a. The dissolved organic matter, cellular morphology, viability, and recovery of M. aeruginosa cells after flocculation and sedimentation were also included. In addition, the effects of pH and addition order of PSFA and PDADMAC on algal removal were investigated. The removal efficiency of algae coagulated using combined PDADMAC and PSFA was improved by 34.5% and 19.3%, respectively. The organic matter removal was also enhanced. The optimum pH range for algal removal is 7.0-10.0, and the preferable addition sequence is the simultaneous addition of PDADMAC and PSFA. Scanning electron microscopy observation indicated that the combined usage of PDADMAC and PSFA caused no damage to the algal cell. Moreover, the experiment on algal recovery demonstrated that PDADMAC has bacteriostatic ability.