Oxygen Mass Transfer in an Airlift Bioreactor using Static Mixers

Investigation of the bacitracin biosynthesis in an airlift bioreactor

“…In this situation, the ability of the enzymatic equipment of cells to hydrolyze the starch is hindered and the culture liquid remains viscous, maintaining a small rate of oxygen transfer. In a previous paper [22] it has been shown that the kLa values in an external-loop airlift reactor using starch solutions of different concentration -up to 4%wt/v -are dependent on the rheological parameters of the liquid phase, the ordinate value (a) of the curve: being dependent on the consistency index value ( K ) in the following form:…”

“…The bioreactor consist of three basic regions [22]: 1) a 0.200 m i.d. riser column into which air is sparged through a stainless steel multi-ring sparger with the hole diameter (6 = 2) a 0.070 m i.d.…”

“…3. In a previous investigation, the kLa values were determined in tap water by the dynamic gassing-in technique [23], using polarographic dissolved oxygen electrodes (INSTRUMENTATION LABORATORY S.p.A, Milan, Italy), connected to a recorder; the oxygen mass transfer coefficient values were obtained from the slope of plots A C J A t vs. (Cs -C L ) , determined from CL variations vs. time [22]. This procedure presupposed a constant gas phase composition and a well mixed liquid phase; also, the absence of a significant delay in the apparent dynamic response time of the dissolved oxygen electrode was considered.…”

Intensification of transfer processes in biotechnology and chemical engineering using static mixers. (Review)

“…In non-Newtonian systems, the improvement in k,a due to static mixers depends on the consistency index, K , or the "thickness" of the fluid: Generally, the thicker the fluid was, i. e. the higher its value of K , the greater the effect of the static mixers was on k,a [38,60]. The k,a may be correlated with the gas superficial velocity, uSG, in an airlift reactor with the following relationship [38, 601: The presence of static mixers affects the u and t values.…”

“…The k,a may be correlated with the gas superficial velocity, uSG, in an airlift reactor with the following relationship [38, 601: The presence of static mixers affects the u and t values. They do not affect t very much, but significantly enhance u dependent on the consistency index in the following form [38,60]:…”