Optimization and operation of a demonstrative full scale microalgae harvesting unit based on coagulation, flocculation and sedimentation

Abstract Biomass harvesting is a bottleneck in microalgae culture and microalgae-based wastewater treatment systems. Sedimentation coupled to coagulation and flocculation has been experimentally studied for a long time, however, full-scale sedimentation experiences have not been addressed so far in literature, and scaling up from experimental results may not be straightforward. The aim of this study was to evaluate the performance of a harvesting unit in a demonstration-scale microalgae biorefinery for wastewater treatment and resource recovery. The unit consisted of coagulation, flocculation and sedimentation within a lamella settler with a volume of 0.7 m3. A high correlation between the influent turbidity and the coagulant dose could be established, so that the coagulant dose could be determined daily just measuring the influent turbidity without performing any jar-test. Suspended solids concentration in the clarified water was always