Biopolishing sanitary landfill leachate via cultivation of lipid-rich Scenedesmus microalgae

Abstract

Sanitary landfill leachate is a toxic effluent with a composition that can vary widely and biological treatment using microalgae represents a promising for bioremediation alternative. In this study, treated sanitary landfill leachate (TSLL) collected after undergoing secondary treatment (biological stabilization pond) was used for the cultivation of Scenedesmus sp. (Chlorophyceae). The TSLL was mixed with tap water to obtain different concentrations (0, 20, 40, 60, 80 and 100% TSLL) before microalgal cultivation aimed at maximizing the production of biomass and lipids. The best concentration for Scenedesmus sp. growth was 80% TSLL, resulting in biomass and lipid productivities of 420 and 36 mg L−1 d−1, respectively, high concentrations of oleic (C18:1) and palmitic (C16:0) fatty acids, and effective removal of nitrogen (NO3−, ∼69%) and phosphorus (PO3−1, 87%). In addition, Scenedesmus sp. removed metals (Al, Cd, Cu, Fe, Ni, Rb and Zn) from the 80% TSLL through biosorption, suggesting that microalga can be used to remediate wastewater that has high polluting capacity. The ability of Scenedesmus sp. to grow in TSLL with high nitrate and heavy metal contents, allows the simultaneously purification of wastewater and the production of a lipid-rich biomass. The proportion of C16-C18 fatty acids in this biomass makes it suitable for biodiesel production.