Strategic growth of limnic green microalgae with phycoremediation potential for enhanced production of biomass and biomolecules for sustainable environment

The approach of combining the microalgae cultivation with wastewater provides a cost-effective and eco-friendly perspective in the production of microalgae-based bio-products. In the present investigation, microalgae Scenedesmus rubescens KACC 2 isolated from catchment region of River Noyyal was found to be efficient in removing nitrogen, phosphorus, and heavy metals from industrial and domestic effluents, which was optimized through central composite design matrix for higher biomass generation. Nutrient requirements for the growth were optimized and evaluated using Plackett-Burman design to check the effect of variables. Three variables, viz., nitrate, phosphate, and inoculums, were found to be significant among the 11 variables tested, and the interaction between these variables and its optimum concentrations were statistically studied using central composite design matrix. The optimized growth conditions of this strain were found to be as nitrate (0.2%), phosphate (0.018%), and inoculums (7.5%). These conditions yielded a higher biomass of 0.73 g/L from the optimized media which was 5.4 times higher than the regular growth media. FT-IR analysis showed the variations in the spectra and also in biomolecular composition with 2-fold increase in the lipid and protein region when grown in optimized culture conditions. Lipid profile showed the presence of saturated and monounsaturated fatty acids in the biomass accepting it as a source of energy feedstock. This study concludes that nitrate, phosphate, and inoculums play a significant role in biomass production of S. rubescens with phycoremediation potential that can be exploited for simultaneous wastewater treatment-coupled biomass production.