An assessment of large scale microalgal harvesting methods for the production of biodiesel

Abstract

Certain species of microalgae, with their high lipid yield, appear to be attractive choices as feedstock for the production of biodiesel. However, their small sizes and low cell concentration make cost effective harvesting one of the most critical areas of industrial production. This present work provides an overview of various separation and dewatering methods with respect to factors such as overall cost, reliability, contamination of products and environmental impacts. On a commercial scale, it appears that harvesting by microbial flocculation followed by dewatering using a combination of belt thickener and belt press provides the most economical process. The overall costs, based on the production from a 1 km2 high rate algal pond, is A$0.32/kg of lipid for harvesting and A$0.09/ kg of lipid for dewatering.