Methane biodegradation in a two-phase partition internal loop airlift reactor with gas recirculation

• Published in: Journal of chemical technology and biotechnology (1986) 2011-03, Vol.86 (3), p.353-360
• Main Authors: Rocha-Rios, José, Quijano, Guillermo, Thalasso, Frédéric, Revah, Sergio, Muñoz, Raul
• Format: Article
• Language: English
• Subjects: Applied sciences; Biodegradation; Biological and medical sciences; Biotechnology; CH4; Chemical engineering; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; gas treatment; Heat and mass transfer. Packings, plates; Mass transfer; mass transfer limitation; Methane; Methods. Procedures. Technologies; Microorganisms; Natural gas; Others; Reactors; silicone oil; Silicones; solid polymers; Solvents; TPPBs; Various methods and equipments
• ISSN: 0268-2575; 1097-4660; 1097-4660
• DOI: 10.1002/jctb.2523

BACKGROUND: The potential of organic liquid solvents and solid polymers to enhance CH₄ mass transfer was studied in a two-phase partition internal loop airlift reactor operated with gas recirculation under biotic and abiotic conditions. A preliminary screening of the most common liquid solvents (silicone oil 20 cSt, silicone oil 200 cSt and 2,2,4,4,6,8,8-heptametilnonane) and solid polymers (Kraton® G6157, Desmopan® DP9370A and Elvax® 880) resulted in the selection of silicone oil 200 cSt (S200) and Desmopan DP9370A (D9370) for further investigation based on their high affinity for CH₄, biocompatibility and nonbiodegradability. RESULTS: Under abiotic conditions, the increase in gas recirculation from 0 to 1 vvm in the absence of a transfer vector increased the overall mass transfer coefficient for oxygen (kLa) by 195%. The presence of S200 and D9370 at 10% (v/v) under operation at 1 vvm of gas recirculation rate mediated an increase in kLa of 100% and 136%, respectively. Likewise, the increase in gas recirculation from 0 to 1 vvm in the absence of a transfer vector and in the presence of S200 during the continuous biodegradation of methane at 3% (v/v) and 7.3 min empty bed residence time resulted in increases in CH₄ removal and CO₂ production rates of 47% and 36%, respectively. Nevertheless, no significant enhancement in CH₄ removal due to the presence of 10% of Desmopan or silicone oil was recorded under operation at 1 vvm. CONCLUSIONS: These results suggest that microbial activity rather than mass transport could be the limiting step in biological CH₄ abatement in this system, contrary to that observed in previous studies with stirred tank reactors, where the organic phase addition increased methane biodegradation. Copyright