Gas‐Liquid Mass Transfer Characteristics in a Rotating‐Drum Bioreactor

Abstract

The oxygen volumetric mass transfer coefficient is a key parameter to characterize the performance of aerobic bioreactors. A novel rotating‐drum bioreactor (RDB) fitted with a sparger as proposed in a previous work has demonstrated its excellent gas‐liquid mass transfer performance. To provide primary information on the design and scale‐up of the novel RDB, effects of reactor configuration including the number and width of lifters and operation conditions such as rotational speed, aeration rate, and solid volume fraction on mass transfer performance were systematically investigated in a new medium‐sized RDB. Compared with the stirred bioreactor and traditional RDBs, this new RDB exhibits better mass transfer performance. Taking both operational and reactor configuration parameters into consideration, an empirical correlation to predict the volumetric mass transfer coefficient in this type of RDBs was proposed which is valuable for its design and scale‐up.

Aeration and mass transfer optimization in a rectangular airlift loop photobioreactor for the production of microalgae

“…The volumetric mass transfer coefficient (k L a) was determined by a traditional Na 2 SO 3 feeding method (Zhang et al, 2012). The concentration of the dissolved oxygen was measured by using a polarographic dissolved oxygen electrode (9), which was located at the midpoint of h tc (seen in Fig.…”

“…Na 2 SO 3 with a concentration of 0.6 mol L À1 was fed into the system by a peristaltic pump (at a rate of 2.7-5.4 ml/min continuously) just 1 cm below the free surface and above the other baffle. The details of experiment can be found in Zhang et al (2012).…”

Power Consumption of Liquid and Liquid/Solid Systems in a Rotating‐Drum Bioreactor

“…The size of alumina particles was in the range of 0-300 lm with d 50 =106 lm. The size distribution of added particles is described in our previous work [21]. The solid volume fraction in the tested liquid/solid system varied between 0 and 5 vol %.…”

“…1 which is similar to the RDB we used to test the mass transfer performance [21] except that 16 groups of screw holes for mounting lifters at -45°or 45°are arranged at both ends of the drum. The configuration parameters of the 93-L medium RDB and the smaller 18-L RDB explored by Jin et al [19] are listed in Tab.…”

“…To achieve suitable fluid motion, furthermore, to form a prescribed shear stress distribution and gas-liquid mass transfer performance, appropriate energy is required to be transferred to the fluid inside a reactor. Compared to a stirred-tank bioreactor, previous experimental investigations in a benchscale RDB (V = 18 L) [19] and a medium-size RDB (V = 93 L) [21] hinted that less power input (total power consumption including system friction) is required to achieve an equal gasliquid mass transfer rate. The investigations on power consumption in stirred-tank reactors manifested that the type of impeller, the off-bottom clearance of impeller, and the impeller space could make significant impact on power consumption [22,23].…”