Temperature induced stress influence on biodiesel productivity during mixotrophic microalgae cultivation with wastewater

The role of operating temperature as a physical stress factor for enhancing lipid induction during microalgae cultivation with domestic wastewater was evaluated. Experiments were designed with dual mode microalgae cultivation viz., growth phase (GP) and temperature induced stress phase (25 degrees C, 30 degrees C and 35 degrees C). GP showed enhancement in biomass growth and carbohydrate accumulation while stress phase (SP) operation at 30 degrees C showed noticeable improvement in lipid productivities (total/neutral lipid, 24.5/10.2%). Maximum carbohydrate utilization was observed during SP at 30 degrees C operation (57.8%) compared to 25 degrees C (50.6%) and 35 degrees C (26.9%) correlating well with the lipid synthesis. Interestingly the neutral lipid content documented five-fold increment illustrating feasibility towards good biodiesel properties. Biodiesel profile at 30 degrees C temperature is well supported by higher saturated fatty acids (SFA) to unsaturated fatty acids (USFA) ratio. GP operation showed good COD and nutrient removal concomitant to the biomass growth. (C) 2014 Elsevier Ltd. All rights reserved.