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

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 (C-18:1) and palmitic (C-16:0) fatty acids, and effective removal of nitrogen (NO3-, similar to 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 C-16-C-18 fatty acids in this biomass makes it suitable for biodiesel production. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study found that a concentration of 80% TSLL is most conducive for the growth of Scenedesmus sp., resulting in increased biomass and lipid production, effective removal of nitrogen and phosphorus, as well as metal removal through biosorption. This suggests the potential for using microalgae in remediating high-polluting wastewater while producing lipid-rich biomass suitable for biodiesel production.