Phycoremediation of Arsenic and biodiesel production using green microalgae Coelastrella sp. M60-an integrated approach

Arsenic (As) contamination is a wide-spread environmental threat, representing serious environmental as well as health-related problems. The present study focuses on Arsenic abatement using phycoremediation and nanoparticle mediated adsorption, proposing an effective and affordable As detoxification with scale-up options. A series of experimental analyses such as Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX), Ion Exchange Chromatography (IC) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), performed, inferred that the microalgal isolate Coelastrella sp. M60 is capable of a 66.26 +/- 1.36, 49.19 +/- 0.103 and 19.20 +/- 1.17 % adsorption of 1, 2, and 3 ppm As V, respectively, at the end of 12 h (analyzed via ICP-OES). Post treatment with TiO2 resulted in increased adsorption %, implying the ability of direct As (III) adsorption by the nanoparticles. Further, the As exposed biomass was subjected to lipid extraction and FAME preparation using four different methods for biodiesel production. The obtained FAME was subjected to biodiesel quality parameters analyses, whose results implied that the As exposed M60 cells demonstrated increased lipid content (1.25 folds higher) and improved FAME production (62.501 +/- 0.979 mg/g biomass), with a 96.70 % of MUFA, yielding good quality biodiesel obtained via a novel, rapid and economical, nanoparticle-pretreated direct transesterification method. Henceforth, the study has unveiled a simple, effective approach for abatement of inorganic As using the microalgae Coelastrella sp. M60, along with the production of good quality biodiesel, by recycling the biomass, previously employed for the bioremediation of As, as a feedstock thus demonstrating a zero waste concept.