Biomass production and harvesting of Desmodesmus subspicatus cultivated in flat plate photobioreactor using chitosan as flocculant agent

Microalgal biomass production has been investigated since the 1950s by academic and industry sectors due to its potential and for biodiesel production. One of the main bottlenecks in microalgae production is biomass recovery and its separation from aqueous medium. For this reason, the use of a flocculation process is an important step to promote microalgae recovery in large scale. Here we provide a strategy for the harvesting of microalgal biomass using chitosan as flocculating agent in pilot scale cultures performed in flat plate photobioreactor. The results show that chitosan was effective in inducing microalgae flocs and separating them by settling. In the jar test scale the best clarification efficiency was around 99% and when scaled up using a 100-L photobioreactor, the biomass recovery efficiency was close to 98%. Comparison of the compositions of biomasses obtained by flocculation and centrifugation indicates no significant differences in terms of carbohydrates, proteins, lipids, and ashes, showing that the flocculation process is not affecting the biomass characteristics and its potential biotechnological applications. Based on the presented results, flocculation using chitosan as flocculant agent can be considered as an efficient method to harvest Desmodesmus subspicatus biomass cultured in pilot scale photobioreactors.