Integrated approach for microbial carbon dioxide (CO2) fixation process and wastewater treatment for the production of hydrocarbons: Experimental studies

Abstract

The present study demonstrates the integration between carbon dioxide [CO2 (g)] fixation process with the wastewater treatment and simultaneous production of value added products utilizing Halomonas stevensii (H. stevensii). Laboratory scale experiments were conducted in a bio-reactor (semi-continuous mode) for 6 days to evaluate the potential of H. stevensii towards biofixation of CO2 (g) [10% (v/v)] in deionized water with 100 mM thiosulphate, domestic wastewater with 100 mM thiosulphate and domestic wastewater. H. stevensii grown on domestic wastewater showed maximum biomass yield, maximum specific growth rate and biomass productivity of 5.31 g L−1, 1.19 d−1 and 3.24 g L−1 d−1, respectively which are comparable with the results obtained from two other culture medias. The possibility for the simultaneous removal of various nutrients and pollutant such as NO3–, NH4+, PO43-, COD and SO42– were also carried out. FTIR and GC-MS analysis of leachate confirmed the presence of fatty alcohols and long chain hydrocarbons in all the three culture medias. The GC-MS analysis of cell lysate and supernatant in all the three culture conditions is dominated by the presence of hydrocarbons and fatty alcohols. Techno-economic analysis of the present system was carried out by estimating the total operating cost per batch and per kg of biomass produced. The assessment indicated the feasibility for the use of domestic wastewater as culture media as a replacement of deionized water with thiosulphate ions.