Department of Chemical Engineering

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Author: search.filters.author.Raghuvanshi, SmitaSubject: search.filters.subject.Thermodynamic analysis

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    Carbon dioxide to bio-fuels by mixed and pure microbial cultures isolated from activated sludge: relative evaluation of CO2 fixation, biodiesel production, and thermodynamic analysis
    (Wiley, 2019-08-31) Gupta, Suresh; Raghuvanshi, Smita; Mishra, Somesh
    In the present work, the CO2(g) bio-mitigation potential (15% [v/v]) of a mixed microbial population, Enterobacter cloacae and Pseudomonas putida, is thermodynamically assessed and compared at different Fe(II) concentrations (energy source). CO2(g) removal efficiency values are evaluated on per-day basis for all cultures and found maximum for the mixed microbial population. Approximate material balance and thermodynamic assessment of the CO2(g) bio-mitigation studies have revealed that among all cultures, the mixed microbial population shows the highest actual CO2 utilization efficiency (R.RCO2) of 57.67 (±0.04)%. Leachate (biomass + cell free supernatant) obtained from CO2 bio-mitigation batch studies were analyzed using FTIR and gas chromatography–mass spectroscopy. The results obtained have shown the presence of fatty acids and hydrocarbons in considerable amounts. The fatty acids obtained from cultures have shown the presence of a carbon chain length in the range of C7–C25, which makes it a potential source of biodiesel. Biodiesel yields of 91.55%, 77.49%, and 38.69% were obtained for the mixed microbial population, E. cloacae and P. putida. The hydrocarbons obtained from all the microbial cultures were found to have a carbon chain length in the range of C9–C32 and comprised saturated and unsaturated groups, which make them comparable to light oil.
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    Investigation on CO2 bio-mitigation using Halomonas stevensii in laboratory scale bioreactor: Design of downstream process and its economic feasibility analysis
    (Elsiever, 2018-03) Gupta, Suresh; Raghuvanshi, Smita; Mishra, Somesh
    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.