Use of microalgae biomass for production of granular nitrogen biofertilizers
Rasa Šlinkšienė, Eglė Sendžikienė, Austėja Mikolaitienė, Violeta Makarevičienė, Rasa Paleckienė, Dovile Ragauskaite
Abstract
This article presents the results of optimizing microalgae Chlorella sp. cultivation to obtain a higher amount of biomass and to use cheaper suitable waste for algae cultivation. It has been found that the most suitable waste for growing microalgae is landfill leachate, which can replace the source of nitrogen in the cultivation medium. The largest concentration of microalgae Chlorella sp. biomass is obtained in the medium containing 0.08 g·L−1 nitrogen acquired from the landfill leachate. For fertilizer production, the microalgae biomass suspension was centrifuged and analyzed. The chemical composition of microalgae biomass was found to be sufficiently good to produce granular nitrogen fertilizer with bioactive materials because it contains primary nutrients (3.49% nitrogen, 2.10% phosphorus, and 0.50% potassium) along with secondary nutrients (13.42% calcium and 3.69% magnesium) and 75.33% organic matter and trace elements. Also, microalgae biomass does not contain any heavy metals. The use of a microalgae suspension allows to reduce the amount of moisture used in the production of fertilizers. If optimal conditions are chosen, it is possible to granulate bioactive nitrogen fertilizer that satisfies all the criteria.