Reforming CO₂ bio-mitigation utilizing Bacillus cereus from hypersaline realms in pilot-scale bubble column...

The bubble column reactor of 10 and 20 L capacity was designed to bio-mitigate 10% CO₂ (g) with 90% air utilizing thermophilic bacteria (Bacillus cereus SSLMC2). The maximum biomass yield during the growth phase was obtained as 9.14 and 10.78 g L^-1 for 10 and 20 L capacity, respectively. The maximum removal efficiency for CO₂ (g) was obtained as 56% and 85% for the 10 and 20 L reactors, respectively. The FT-IR and GC-MS examination of the extracellular and intracellular samples identified value-added products such as carboxylic acid, fatty alcohols, and hydrocarbons produced during the process. The total carbon balance for CO₂ utilization in different forms confirmed that B. cereus SSLMC2 utilized 1646.54 g C in 10 L and 1587 g of C in 20 L reactor out of 1696.13 g of total carbon feed. The techno-economic assessment established that the capital investment required was $286.21 and $289.08 per reactor run of 11 days and $0.167 and $0.187 per gram of carbon treated for 10 and 20 L reactors, respectively. The possible mechanism pathways for bio-mitigating CO₂ (g) by B. cereus SSLMC2 were also presented utilizing the energy reactions. Hence, the work presents the novelty of utilizing thermophilic bacteria and a bubble column bioreactor for CO₂ (g) bio-mitigation.