A hybrid approach integrating arsenic detoxification with biodiesel production using oleaginous microalgae

A novel combinatorial approach integrating toxic and carcinogenic heavy metal arsenic (III, V) mitigation coupled to biodiesel production using oleaginous microalgae grown in synthetic soft water (SSW) was undertaken in this investigation. Among the four prospective microalgal species tested, Chorella minutissima and Scenedesmus sp. IITRIND2 were able to tolerate 500 mg L-1 of both the forms of As (III) and As (V) with a high metal bioconcentration factor (BCF) indicating that these strains can be categorized as hyper bioaccumulators of arsenic. These arsenic spiked microalgae showed a significant enhancement in the lipid production by accumulating large lipid droplets with minimal morphological changes. The biochemical composition analysis of these microalgal cells showed apparent decline in the protein, carbohydrate and photosynthetic pigments suggesting that the arsenic intake by the cells has remodeled its cellular composition in order to cope up with the heavy metal induced stress. The biodiesel derived from the microalgae was amenable and comparable to plant oil methyl esters with a high cetane number, oxidative stability and low cold flow plugging properties. This salient approach exhibits two fold advantages, which include safe removal of carcinogenic metal arsenic from potable water sources as well as high yield of lipid production. This novel integrative innovative technology has a strong prospective path for verdurous environment and renewable fuels resulting in socioeconomic welfare. (C) 2017 Elsevier B.V. All rights reserved.