Consolidated bioprocessing of wastewater cocktail in an algal biorefinery for enhanced biomass, lipid and lutein production coupled with efficient CO2 capture: An advanced optimization approach

Abstract

We present a holistic approach in establishing a successful green integrated bio-refinery system with improved biomass, lipid and lutein productivity, while remediating wastewater and sequestering CO2 with potential biodiesel and healthcare applications. To achieve this we evaluated the effect of four process parameters: CO2% supply; acetate concentration; poultry litter waste (PLW) concentration; and light intensity on cultivation of Chlorella minutissma following the Taguchi's design of experimental technique. A four factors, three levels orthogonal array was adopted to cultivate Chlorella minutissma in specially developed waste water medium. Effect of the process parameters on biomass productivity, CO2 fixation rate, lipid content, lutein productivity and bioremediation capacity were determined. Results obtained from individual parametric combinations and Signal/Noise (S/N) ratio responses indicated S3 (5% CO2, 100 mg L−1 of acetate, 10 g L−1 of poultry litter, and 15, 000 lux of light intensity) combination as the optimum cultivation condition. Following the S3 combination a significant enhancement in biomass productivity (292 mg L−1 d−1) with exceedingly high CO2 fixation rate and photosynthetic efficiency (51.51 g L−1 d−1 of CO2; P.E: 15.81%) was achieved. A maximum of 169.29 mg L−1 d−1 of lipid with a balanced distribution of saturated and unsaturated fatty acids conformed to the international standard for biodiesel was achieved. Additionally, 7.21 mg L−1 d−1 of lutein productivity was also accomplished within 7 day of cultivation, while remediating up to 93-90% of nitrogenous and phosphate substrates. Statistically, the results reinforced our findings with the S/N responses and experimental observations for a particular property.