Preparation and characteristics of bacterial polymer using pre-treated sludge from swine wastewater treatment plant

Schematic diagram of flocculation mechanism of bioflocculant MBFRR3. The flocculation of kaolin particles was completed by charge neutralization and bridging mechanism by addition Ca2+ in two steps, coagulation and flocculation. First step was the coagulation, in which Ca2+ draw closer to the negatively charged kaolin particles through columbic attraction and Ca2+-kaolin complexes were formed. Ca2+ reduced the thickness of the diffuse double layer of adjacent kaolin particles and hence, reducing the inter particle distance between particles. This phenomenon was evidenced by the decrease of Zeta potentials of kaolin suspensions after Ca2+ addition. Second step was the flocculation, in which bioflocculants act like a bridging agent of two or more Ca2+-kaolin complexes and reduces inter-particle distances through the ionic bonds mechanism, and bridging occurred after the Ca2+-kaolin complexes adsorbed onto the bioflocculants chains.