Bio-Mitigation of Carbon Dioxide Using Desmodesmus sp. in the Custom-Designed Pilot-Scale Loop Photobioreactor.

Today's society is faced with many upfront challenges such as the energy crisis, water pollution, air pollution, and global warming. The greenhouse gases (GHGs) responsible for global warming include carbon dioxide (CO₂), methane (CH₄), nitrous oxide (NO_x), water vapor (H₂O), and fluorinated gases. A fraction of the increased emissions of CO₂ in the atmosphere is due to agricultural and municipal solid waste (MSW) management systems. There is a need for a sustainable solution which can degrade the pollutants and provide a technology-based solution. Hence, the present work deals with the custom design of a loop photobioreactor with 34 L of total volume used to handle different inlet CO₂ concentrations (0.03%, 5%, and 10% (v/v)). The obtained values of biomass productivity and CO₂ fixation rate include 0.185 ± 0.004 g L⁻¹ d⁻¹ and 0.333 ± 0.004 g L⁻¹ d⁻¹, respectively, at 10% (v/v) CO₂ concentration and 0.084 ± 0.003 g L⁻¹ d⁻¹ and 0.155 ± 0.003 g L⁻¹ d⁻¹, respectively, at 5% (v/v) CO₂ concentration. The biochemical compositions, such as carbohydrate, proteins, and lipid content, were estimated in the algal biomass produced from CO₂ mitigation studies. The maximum carbohydrate, proteins, and lipid content were obtained as 20.7 ± 2.4%, 32.2 ± 2.5%, and 42 ± 1.0%, respectively, at 10% (v/v) CO₂ concentration. Chlorophyll (Chl) a and b were determined in algal biomass as an algal physiological response. The results obtained in the present study are compared with the previous studies reported in the literature, which indicated the feasibility of the scale-up of the process for the source reduction of CO₂ generated from waste management systems without significant change in productivity. The present work emphasizes the cross-disciplinary approach for the development of bio-mitigation of CO₂ in the loop photobioreactor. [ABSTRACT FROM AUTHOR]