POLLUTION CONTROL TECHNOLOGIES AND ALTERNATE ENERGY OPTIONS Mixotrophic cultivation of microalgae using industrial flue gases for biodiesel production Pooja Kandimalla 1 & Sreekanth Desi 1 & Himabindu Vurimindi 1 Received: 13 March 2015 /Accepted: 17 August 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract In the present study, an attempt has been made to grow microalgae Scenedesmus quadricauda, Chlorella vulgaris and Botryococcus braunii in mixotropic cultivation mode using two different substrates, i.e. sewage and glucose as organic carbon sources along with flue gas inputs as inor- ganic carbon source. The experiments were carried out in 500 ml flasks with sewage and glucose-enriched media along with flue gas inputs. The composition of the flue gas was 7 % CO 2 , 210 ppm of NO x and 120 ppm of SO x . The results showed that S. quadricauda grown in glucose-enriched medi- um yielded higher biomass, lipid and fatty acid methyl esters (FAME) (biodiesel) yields of 2.6, 0.63 and 0.3 g/L, respec- tively. Whereas with sewage, the biomass, lipid and FAME yields of S. quadricauda were 1.9, 0.46, and 0.21 g/L, respec- tively. The other two species showed closer results as well. The glucose utilization was measured in terms of Chemical Oxygen Demand (COD) reduction, which was up to 93.75 % by S. quadricauda in the glucose-flue gas medium. In the sewage-flue gas medium, the COD removal was achieved up to 92 % by S. quadricauda. The other nutrients and pollut- ants from the sewage were removed up to 75 % on an average by the same. Concerning the flue gas treatment studies, S. quadricauda could remove CO 2 up to 85 % from the flue gas when grown in glucose medium and 81 % when grown in sewage. The SO x and NO x concentrations were reduced up to 50 and 62 %, respectively, by S. quadricauda in glucose-flue gas medium. Whereas, in the sewage-flue gas medium, the SO x and NO x concentrations were reduced up to 45 and 50 %, respectively, by the same. The other two species were equally efficient however with little less significant yields and removal percentages. This study laid emphasis on comparing the feasibility in utilization of readily available carbon sources like glucose and inexpensive leftover carbon sources like sew- age by microalgae to generate energy coupled with economi- cal remediation of waste. Therefore on an industrial scale, the sewage is more preferable. Because the results obtained in the laboratory demonstrated both sewage and glucose-enriched nutrient medium are equally efficient for algae cultivation with just a slight difference. Essentially, the sewage is cost effective and easily available in large quantities compared to glucose. Keywords Flue gas . Microalgae . Sewage . Biodiesel . Lipid Introduction Fossil fuels contribute most of the global energy demand, but these fuels are directly associated with the greenhouse effect and environmental pollution. Oil reserves may run out after 2050 due to the fast growing human activities worldwide which require fossil fuels (IEA 2007). Therefore, huge efforts are being made in developing CO 2 fixation and reduction technologies and in finding alternative and renewable energy sources (Chiu et al. 2009; Brown and Zeiler 1993). Among those attempts, biodiesel has received significant attention since it was made from nontoxic and biodegradable materials, and its use leads to a huge decrease in the emissions of green- house gases (such as CO 2 ) and air pollutants. However, to produce enough biodiesel from oleaginous crops (such as soy- bean, palm, and rapeseed) to supply the existing demand for Responsible editor: Philippe Garrigues * Himabindu Vurimindi drvhimabindu@gmail.com 1 Center for Environment, Institute of Science and Technology, Jawaharlal Nehru Technological University, Kukatpally, Hyderabad 500 085, India Environ Sci Pollut Res DOI 10.1007/s11356-015-5264-2