Microalgae cultivation in treated landfill leachate: biomass productivity and lipid characterization aiming biodiesel production.

Abstract

Producing biodiesel from alternative biomass sources is a promising strategy for sustainable energy systems. This study evaluated urban landfill leachate treated by an advanced oxidative process (AOP) as an alternative to synthetic media for microalgae cultivation aimed at biodiesel production. The leachate was treated under ultraviolet (UV) irradiation with hydrogen peroxide in a photochemical system. A 2² factorial design assessed the effects of UV lamp power (0, 15, and 28 W) and hydrogen peroxide feeding time (90, 120, and 150 min). UV power significantly affected leachate degradation, reaching 57.3% reduction in total organic carbon. Treated leachate was then used as a culture medium for Nannochloropsis gaditana at concentrations of 50%, 80%, and 100% (v/v). The highest biomass productivity (381.62 mg L^-1day^-1) and lipid productivity (115.87 mg L^-1day^-1) were obtained with 50% treated leachate combined with conventional medium. Fatty acid analysis showed predominance of saturated and monounsaturated fatty acids, indicating favorable cetane number and oxidative stability, despite possible cold-flow limitations. The results demonstrate the potential of treated landfill leachate for microalgal cultivation and biodiesel production within a circular bioeconomy approach.