title: Comparative performance evaluation of conventional and two-phase hydrophobic stirred tank reactors for methane abatement: Mass transfer and biological considerations.
abstract: This study demonstrated for the first time the capability of methanotrophs to grow inside silicone oil (SO200) and identified the optimum cultivation conditions for enrichment of hydrophobic methanotrophs (high dilution rates (D) and low CH4 transfer rates). The potential of the hydrophobic methanotrophs enriched was assessed in a single-phase stirred tank reactor (1P-STR) and in a two-phase stirred tank reactor (2P-STR). Different operational conditions were systematically evaluated in both reactors (SO200 fractions of 30 and 60 %, stirring rates of 250 and 500 rpm, and D of 0.1-0.35 day(-1) with and without biomass retention). The results showed that the TPPB only supported a superior CH4 abatement performance compared to the 1P-STR (40% enhancement at 250 rpm and 25% enhancement at 500 rpm) at a D of 0.3 day(-1) due to the retention of the biocatalytic activity inside the SO200, while the 1P-STR achieved higher elimination capacities (EC up to ≈3 times) than the TPPB under the rest of conditions tested (ECmax  = 91.1 g m(-3)  h(-1) ). Furthermore, the microscopic examination and DGGE-sequencing of the communities showed that the presence of SO200 influenced the microbial population structure, impacting on bacterial biodiversity and favoring the growth of methanotrophs such as Methylosarcina. Biotechnol. Bioeng. 2016;113: 1203-1212. © 2015 Wiley Periodicals, Inc.
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina, s/n, 47011, Valladolid, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Cantera
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina, s/n, 47011, Valladolid, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Estrada
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina, s/n, 47011, Valladolid, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Lebrero
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina, s/n, 47011, Valladolid, Spain.
authors.forename: Pedro A
authors.initials: PA
authors.lastname: García-Encina
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina, s/n, 47011, Valladolid, Spain. mutora@iq.uva.es.
authors.forename: Raúl
authors.initials: R
authors.lastname: Muñoz
mesh_terms: D000393:Air Pollutants / Q000378:metabolism*; D061249:Batch Cell Culture Techniques / Q000295:instrumentation*; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology*; D002470:Cell Survival / Q000502:physiology*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D020563:Gammaproteobacteria / Q000145:classification / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D008697:Methane; D012212:Rheology / Q000295:instrumentation; D012827:Silicone Oils / Q000737:chemistry*; D013045:Species Specificity
chemical_list: D000393:Air Pollutants; D012827:Silicone Oils; D008697:Methane
keywords: CH4 abatement; hydrophobic bacteria; mass transfer limitation; methanotrophs; two-phase partitioning bioreactors