Preparation of a novel inorganic-biological composite flocculant for the removal of turbidity and organic matter in the surface water

This study presents the preparation of a novel inorganic-biological composite flocculant, termed PAFC-CBF, which is composed of polymeric aluminum ferric chloride (PAFC) and compound bioflocculant (CBF). It was investigated under different PAFC/CBF weight ratios. The turbidity and total organic carbon (TOC) removal efficiency were also investigated, when PAFC-CBF was added to the surface water. Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy were performed to characterize PAFC-CBF. Finally, floc properties including floc strength and recoverability were investigated using Mastersizer 2000. The results of the investigation indicated that CBF was successfully embedded into PAFC, forming a novel flocculant with the characteristic structure of PAFC and CBF. Considering the flocculation efficiency and economic cost, PAFC-CBF demonstrated a superior flocculation performance at the flocculant dosage of 25 mg/L, with an optimal turbidity removal efficiency of 90.28%, and a TOC removal efficiency of 26.75%. During the flocculation process, charge neutralization, adsorption bridging and sweep mechanisms served in the main role of colloidal destabilization and aggregation.