A Novel and Rapid Harvesting Method of Microalgae Using Saw Dust Coated Polypyrrole

In this study a simple and rapid harvesting method using electro conductive polymer coated saw dust has been presented as a new coagulant for separating Chlorella vulgaris from a diluted suspension. Polypyrrole (PPy) coated saw dust as a novel coagulant was prepared via in-situ polymerization of pyrrole (Py) monomer using FeCl3 oxidant in aqueous medium in which saw dust particles were suspended. The zeta potential of coagulant and C. vulgaris and X-ray photoelectron spectroscopic (XPS) analysis of coagulant were characterized. PPy maintain predominantly positive charge over a wide pH range (2-10) with an isoelectric point 10.4 while, C. vulgaris maintained negative surface charge from pH 5 and onward with isoelectric point 3.8. The microalgae showed the highest separation efficiency at pH 10. The maximal recovery efficiency reached more than 90% for microalgae at a stirring speed of 120 rpm within 7 min. The maximal adsorption capacity of C. vulgaris was 28.8 mg dry biomass/mg-saw dust coated PPy. The concentration factor obtained is higher than 32 which save energy and time associated with microalgal harvesting and allows a reduction in the equipment size necessary for biomass dewatering and improves the feasibility of using these microorganisms in biofuel or wastewater processes.