Design of cost effective photobioreactor (PBR) for mass production of microalgae: Experiments and CFD simulations

A) Integrated process of CO2 mitigation and wastewater treatment using microalgae on pilot scale to yield biofuels: Various microalgae strains have been found to produce the suitable feedstock for biofuels production. Although microalgae are having several advantages such as rapid growth, higher lipid productivity, and robustness to various environmental conditions, and sought one of the major promising alternative sources of liquid biofuels, the present cost of microalgae production is very high. One way to lower the cost of production is to use the wastewater instead of freshwater which also satisfies the need of nitrogen and phosphorous, the most required elements for microalgae growth. The production of microalgal biofuels seems to be viable on a large scale with the use of wastewater, industry emitted CO2 and freely available sunlight for cultivation of microalgae. The optimal ways to enhance total lipid content of microalgae under different modes of cultivation (autotrophic as well as mixotrophic mode) is under investigation. The main objective is to see the feasibility of microalgae cultivation in these modes along with maximum possible sequestration of CO2. B) Design of vertical gas sparged PBR The cultivation of microalgae is very sensitive to temperature, pH, shear stress, irradiance, and operating conditions of PBR. Suitable strategies are needed to enhance the biomass and lipid productivity in vertical tubular column PBR. The understanding of design parameters is a prerequisite for scale-up of gas sparged vertical column PBRs. The hydrodynamics of gas sparged vertical column PBRs play a very important role in the biomass production and avoiding carbon loss (unabsorbed CO2 out of total supplied). Hence, the hydrodynamic aspects of two and three phase flow in the vertical column PBR are emphasized with respect to its scale-up prospect. The flow regimes and CFD modelling aspects of gas sparged PBRs are key areas to be focused in this study