Aeration sparging

Commercial-scale operations are conducted in batch, fed-batch, or continuous culture systems. Fermentation vessels include the conventional baffled aerated tank, with or without impeller agitation, and the ak-lift tower fermentors in which ak is sparged into an annular space between the... 

Oxygen, when introduced into fish-farming ponds and pools, particularly trout pools, enables these fish to increase their food intake and hence grow more rapidly (see Aquaculture chemicals). Fermentation operations are accelerated by sparging with oxygen (see Aeration,biotechnology Ferl ntation). 

A 2 IB. Braun airlift fermenter with a working volume of about 2000 ml was used. Sterile air is sparged through a sintered plate located near the bottom of the central concentric tube. There was no mechanical stirring only the air nozzle was forced through the centred tube and the flow directed to the annulus tube side. Aeration causes circulation of media the flow is gentle without serious shear forces. The temperature is maintained at 26 °C. 

The most common applications of air sparging are in-well aeration and injection well aeration. Where air sparging releases a significant quantity of volatile organic chemicals, an SVE system is often installed in the vadose zone to intercept the vapors for aboveground treatment. 

Several variations of air sparge procedures are currently in common use, with each designed for site-specific situations. Vacuum vaporization is accomplished by attaching a vacuum pump to the top of an in-well aeration system. The vacuum removes the vapors and also draws soil vapors from the vadose zone. The combination of air sparging and SVE can provide effective capture of vapors with a minimum of wells. 

T0012 Advanced Processing Technologies, Inc., Air-Sparged Hydrocyclone T0020 Aeration Basins—General... 

Probably the major problem in the scale-np of fermentation processes lies in maintaining aeration efficiency to aerobic cultnres. Aeration is normally achieved by sparging with air and the rate determining step in a non-viscons fermentation is the... 

Frmdamentally, air-lift bioreactors are a modification of the bubble colunms that generate air-flow for medium circulation unidirectionally by having at least two columns—a raiser column and a downer column. They are either a draft tube or an external loop bioreactor. The bubbles sparged into a draft tube generate upward flow and medium pours into the annular space between the draft tube and bioreactor vessel and flows downwards. An essential design feature to consider is the bioreactor ratio of the height (H) to the diameter (D). Values of H/D of five or more are needed for sufficient mixing (18). Efficiency of medium circulation depends on the rate of aeration and on the ratio of the cross-sectional area of the draft tube to the total... 

The ratio of the power requirement of gas-sparged (aerated) liquid in a stirred tank, Pq, to the power requirement of ungassed liquid in the same stirred tank, Pq, can be estimated using Equation 7.34 [7]. This is an empirical, dimensionless equation based on data for six-flat blade turbines, with a blade width that is one-fifth of the impeller diameter d, while the liquid depth Hp is equal to the tank diameter. Although these data were for tank diameters up to 0.6 m. Equation 7.34 would apply to larger tanks where the liquid depth-to-diameter ratio is typically... 

It would be more practical, if A in gas-sparged stirred tanks were to be directly correlated with operating variables and liquid properties. It should be noted that the definition of k a for a gas-sparged stirred tank (both in this text and in general) is based on the clear liquid volume, without aeration. 

Two major types of fermentors are widely used in industry. The stirred tank, with or without aeration (e.g., air sparging) is most widely used for aerobic and anaerobic fermentations, respectively. The bubble column (tower fermentor) and its modifications, such as airlifts, are used only for aerobic fermentations, especially of a large scale. The important operating variables of the sparged (aerated)... 

Values of kj a for viscoelastic liquids in aerated stirred tanks are substantially smaller than those in inelastic liquids. Moreover, less breakage of gas bubbles in the vicinity ofthe impeller occurs in viscoelastic liquids. The following dimensionless equation [8] (a modified form of Equation 7.37) can be used to correlate kj a in sparged stirred tanks for non-Newtonian (including viscoelastic) liquids ... 

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