Investigation on CO2 bio-mitigation using Halomonas stevensii in laboratory scale bioreactor: Design of downstream process and its economic feasibility analysis

Abstract

In the present study, H. stevensii was cultivated on a semi-continuous mode in a laboratory scale bio-reactor using CO2(g) [15% (v/v)] as carbon source and thiosulfate (S2O32−) as an energy source for the total duration of three days. Approximately, 100% CO2(g) removal from gaseous phase was achieved. Leachate obtained was subjected to different downstream bio-processing strategies. Biomass harvesting using filtration and recovery of metabolites without cell disruption using solvent extraction from wet biomass was observed as the best downstream processing strategy. Qualitative analysis of products was carried out using gas chromatography and mass spectroscopy (GC–MS) and their results have indicated fatty alcohols (C8–C27) as primary metabolites. Fourier transform infrared spectroscopy (FTIR) analysis, approximate material balance and thermodynamic analysis have confirmed the intracellular assimilation of CO2(g) as HCO3− and its metabolization into fatty alcohols. Economic feasibility of the process has suggested that the developed downstream process has the capability to replace coconut oil based process for the production of fatty alcohols (C12–C14) and it can be utilized for the production of dodecanol as compared to the tetradecanol.