Here is disclosed a cell culture tank comprising a cylindrical screen mounted upright within the cell culture tank and having upper and lower openings through which culture medium flows, a pipe for supply of oxygen or oxygen containing gas and an agitator adapted to produce a flow of the culture medium, both the pipe and the agitator being provided within the cylindrical screen, wherein the agitator drives the culture medium to flow downward through the lower opening of the cylindrical screen, then to flow upward into a space defined between the cylindrical screen and the inner wall of the cell culture tank, and a relationship between an ascending velocity of the culture medium and a sinking velocity of the adherent carriers produces in the space between the cylindrical screen and the inner wall of the cell culture tank a floating region within which the adherent carriers float in the culture medium and a separating region within which the adherent carriers are separated from the culture medium.

System and method for diffusing gas bubbles into a pond, lagoon or basin that is used for fish farming or other form of aquaculture. A small amount of water is continuously removed from the bottom of the body of water by one or more counterflow gas lift diffusers. This small amount of water is flowed down underground, has gas bubbles introduced into it, and is then returned to the body of water. The quantity of water removed and treated in this way is a small fraction of the total body of water in the pond, lagoon or basin. The ratio of (1) the total volume of the channels below ground through which the water flows downward, and then back up into the body of water, to (2) the volume of the body of water above ground is at all times less than about 1:100. In the broadest form of the invention, a gas diffuser introduces gas bubbles into the water in the return channel at a level at least about 2 feet below the bottom of the body of water, and no more then about 50 feet below the surface of the body of water being treated. The downflow and return channels and the space joining them at their bottom ends extend no more than about 50 feet below the surface of the water being treated.

An absorber for absorbing a vapor into a sorbent liquid comprised of a sequential plurality of highly effective and intensified locally cocurrent sorptions, but with non-cocurrent flow of vapor and liquid between the individual sorptions. The structure containing the locally cocurrent upflow is preferably comprised of enhanced heat transfer surface, making the sorption diabatic, further enhancing the intensification, and improving the sorption efficiency. Referring to FIG. 1, vertical cylinders (1) and (2) form an annulus which is divided into multiple compartments by partitions. Vapor is injected into the bottom portion of each compartment by injection ports (10), resulting in cocurrent upflow absorption. The compartments are pressure equalized with a common vapor space via equalization ports (6). This approach to absorption can be accomplished in a vertical cylindrical annulus as described above, in a horizontal cylindrical annulus, in plate fin exchangers, and others.