Effect of silicone oil fraction and stirring rate on methane degradation in a stirred tank reactor

Abstract

BACKGROUND: Methane is an important greenhouse gas and its biological oxidation constitutes a cost-effective alternative for low concentration emissions. Nevertheless, due to its low aqueous solubility (similar to oxygen), gas mass transfer is often the limiting step. Two-phase partition bioreactors (TPPBs), have been proposed to increase the biodegradation of poorly soluble compounds. In this work, the effect of stirring rate and silicone oil fraction on abiotic volumetric oxygen transfer coefficient k L a O 2 and methane elimination capacity (EC) by a methanotrophic consortium in a stirred tank was studied.

Ionic liquids: Applications and future trends in bioreactor technology

“…For instance, it is well known that solvents with low surface tension promote foam stability, an undesirable effect that must be avoided (Quijano et al, 2009a). On the other hand, a highly viscous solvent may significantly affect the power requirements for mixing purposes, increasing finally the overall cost of the process (Galaction et al, 2004;Rocha-Rios et al, 2010).…”

“…These values are significantly higher than those previously reported for other NAPs. For instance, K L a values from 40 to 70 h À1 have been reported for n-hexadecane and silicone oils of 200 and 300 cSt under similar reactor design and operating conditions (Aldric et al, 2009;Nielsen et al, 2003;Rocha-Rios et al, 2010). Unfortunately, the authors did not provide mass transfer data in the absence of ILs and thus, oxygen transfer improvement or repression by IL addition is still unclear.…”

The role of paraffin oil on the interaction between denitrifying anaerobic methane oxidation and Anammox processes

“…High-pressure bioreactors are specialized, complex, expensive, and dangerous, whereas adding a second liquid phase is relatively easy and cheap. For example, n-dodecane can enhance the oxygen mass transfer in broths (Galaction et al 2005;Lai et al 2002), and increasing the silicone oil fraction in two-phase partition bioreactors can improve biological methane oxidation (Rocha-Rios et al 2010). Paraffin oil is non-volatile, dissolves sparingly in water, is nontoxic to microbes, and has a higher solubility of methane, which is about ten times higher than water; hence, it is a potential methane vector.…”

Production of poly-β-hydroxybutyrate (PHB) by Methylobacterium organophilum isolated from a methanotrophic consortium in a two-phase partition bioreactor

“…This limitation can be represented considering an example using methane at 5% (around 25 g m −3 ) which is around the LEL value. The equilibrium in liquid is roughly 0.8 g m −3 and assuming a k l a value of 40 h −1 [39] yields a maximum volumetric transfer of about 32 g m −3 h −1 or 768 g m −3 d −1 . The EC enhancement observed in experiments using silicone oil is related to the increased availability of CH 4 , associated with the decrease of the Henry's coefficient.…”