Production, purification and application of polysaccharide-based bioflocculant by Paenibacillus mucilaginosus

The production and purification of polysaccharide-based bioflocculants (PSBs) by Paenibacillus mucilaginosus GIM1.16 in metal ion-supplemented medium and basal medium were evaluated. Three purified PSB1-1, PSB2-1 and PSB3-1 possessed different monosaccharide composition and their molecular weights were 2.53 × 106, 7.77 × 106 and 13.2 × 106 Da, respectively. FT-IR spectrometry indicated the presence of hydroxyl, carboxyl and phosphate groups in the three samples. Scanning electron microscopy showed that they had linear structure. The potential of these PSBs on wastewater treatment was evaluated. Among them, PSB1-1 exhibited the best performance, as it had high flocculating activities (above 94%) at 0.5-4 mg/L and could achieve high flocculating activities (above 97%) in the kaolin suspensions of pH 3-9. PSB1-1 was the key factor that might explain the enhanced flocculating activity of the supernatant from metal ion-supplemented medium. The performance of PSB1-1 on industrial wastewater was also satisfactory. PSB1-1 might be a good candidate as bioflocculant.