Characterization and flocculation mechanism of high efficiency microbial flocculant TJ-F1 from Proteus mirabilis

The characterization and the flocculation mechanism of microbial flocculant TJ-F1 with high flocculating activity, produced by Proteus mirabilis from a mixed activated sludge, was investigated. Mainly consisting of protein and acid polysaccharide, TJ-F1 owns a molecular weight of 1.2 × 105 Da, which brings strong van der Waals forces and ample binding-sites. It contains carboxyl, hydroxyl, amino groups and hydrogen bonds preferred for the flocculation process. The key parameters influencing the flocculation behavior were investigated by analyzing both the Zeta potentials of the flocculation systems and the flocculating efficiencies of TJ-F1. An alkaline condition promotes its flocculating efficiency. CaCl2 aids TJ-F1 by effectively decreasing the absolute value of Zeta potential. Appropriate dose of TJ-F1 is crucial to the flocculating efficiency. During the precipitating process, the growing flocs sweep the small flocs and the suspended particles to form big flocs, which also contribute to the excellent flocculating efficiency of TJ-F1.