On-site concurrent carbon dioxide sequestration from flue gas and calcite formation in ossein effluent by a marine cyanobacterium Phormidium valderianum BDU 20041 Gnanasekaran Dineshbabu, Vaithyalingam Shanmugasundaram Uma, Thangavel Mathimani, Garlapati Deviram, Devanesan Arul Ananth, Dharmar Prabaharan, Lakshmanan Uma ⇑ National Facility for Marine Cyanobacteria (Sponsored by DBT, Govt. of India), Department of Marine Biotechnology, School of Marine Sciences, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India article info Article history: Available online xxxx Keywords: CO 2 sequestration Cyanobacteria Biodiesel Ossein effluent Flue gas Biocalcification abstract In the recent past, there has been an upsurge in the use of microalgae to capture CO 2 . Microalgae are the most productive biological systems for generating biomass; they produce much more biomass than ter- restrial organisms. In the present study, a cyanobacterium was exploited for combined CO 2 capture and ossein effluent treatment. Phormidium valderianum BDU 20041, a non-heterocystous filamentous marine cyanobacterium was grown in an open tank (550 L) in ossein effluent using flue gas (coal burnt) after cooling. After 10 days with unscrubbed flue gas, the organism’s biomass productivity, specific growth rate, CO 2 fixation rate, and lipid content were 30 mg L 1 d 1 , 0.10 l d 1 , 56.4 mg C L 1 d 1 , and 12.74%, respectively. The predominance of C14 and C18 fatty acids in the total lipid content revealed its suitabil- ity as a potential biofuel. Results of this study show that flue gas from a coke oven can be used for mass cultivation of P. valderianum BDU 20041, which efficiently captures CO 2 and remediates ossein wastew- ater. Calcite formation by the organism in effluent was confirmed by scanning electron microscopy and energy dispersion spectroscopy studies. Biomass production employing flue gas coupled with the biomin- eralization of CO 2 in ossein effluent at a point source offers a novel self-sustaining strategy to mitigate CO 2 through outdoor cultivation and the subsequent generation of a biodiesel feedstock. Ó 2016 Elsevier Ltd. All rights reserved. 1. Introduction The current increase in carbon emissions needs to be abated to prevent atmospheric carbon dioxide (CO 2 ) from reaching the alarming level of 450 ppm soon (current value 401.14 ppm) [1]. Although there are mixed opinions on the precise effects of increasing carbon levels, increased CO 2 is generally accepted as having an adverse impact on the environment. The surface temper- ature has already increased approximately by 1.211 °C since 1880. The major cause of this increase in emission is the burning of coal in power plants [2]. A complete elimination of carbon emissions is impossible, but the level of CO 2 emitted into the atmosphere can be controlled. Strategies to mitigate emissions of CO 2 from fossil fuels include energy savings, development of renewable biofuels, and carbon capture and storage (CCS). CCS methods include physical, geological, chemical, and biological approaches. Methods other than biological ones involve a high cost to separate and store CO 2 from flue gas [3]. Biomineralization of CO 2 by calcium carbon- ate (CaCO 3 ) precipitation is a common phenomenon in marine, freshwater, and terrestrial ecosystems, and this is a fundamental process in the global carbon cycle [4]. Biological sequestration can be very effective, as this does not involve separation of CO 2 and storage of carbon as a biomass, and it has commercial virtues such as the production of biofuels, pigments, and other value- added compounds [5]. Flue gas from most power plants primarily contains CO 2 (10–12%, v/v), sulfur oxides (220 ppm SOx), and nitrogen oxides (400 ppm NOx) [6], along with other minor gaseous elements. The present oxygenic atmosphere was originally formed by cyanobacteria during the Archaean and Proterozoic Eras, which had high CO 2 atmospheres. Cyanobacteria generally thrive in high CO 2 conditions and are considered efficient systems for CO 2 capture from flue gas [7]. Halophilic and marine cyanobacteria are versatile; they can be cultured in marine waters, saline drainage water, or http://dx.doi.org/10.1016/j.enconman.2016.09.040 0196-8904/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: pub_nfmc@yahoo.com (L. Uma). Energy Conversion and Management xxx (2016) xxx–xxx Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman Please cite this article in press as: Dineshbabu G et al. On-site concurrent carbon dioxide sequestration from flue gas and calcite formation in ossein efflu- ent by a marine cyanobacterium Phormidium valderianum BDU 20041. Energy Convers Manage (2016), http://dx.doi.org/10.1016/j.enconman.2016.09.040