Nannochloropsis Oceanica Biomass Enriched by Electrocoagulation Harvesting with Promising Agricultural Applications

Abstract

Electrocoagulation is a promising technology to harvest and concentrate microalgae while saving costs on secondary dewatering steps. However, the sacrificial electrodes release salts that impact the media and the harvested biomass. This study evaluated the effects of Fe, Zn, and Mg electrodes on Nannochloropsis oceanica harvesting and elementary composition of biomass and supernatants. Moreover, the bioavailability of the minerals coupled to the biomass was assessed in Solanum lycopersicum plants. Fe electrodes had better performance at lower power consumption and operation costs, followed by Zn and Mg. Electrocoagulation changes in biomass and supernatants’ composition were electrode dependent. However, co-precipitation of Mg and Ca enriched N. oceanica biomass from all electrodes, but increased Pb 2-4 times and depleted P in supernatants. Finally, Fe and Mg electrode metals in the biomass were proven bioavailable to S. lycopersicum seedlings, making electrocoagulation harvested biomass a promising bioresource to agricultural applications.

Keywords: Microalgae, Electrocoagulation, Alternative electrodes, Harvesting, Plant nutrition, Plant Stress