a function of time. As long as the process is in steady state, the liquid will not overflow into the foaming column. Depending on the design of the foam separator, the location of the feed flowing in can vary from atop of the liquid solution to the top of the foam column. The creation of the foam starts with the flow of gas into the bottom of the liquid column. The amount of gas flow into the apparatus is measured and maintained through a flow meter. As the foam rises and becomes drained of the liquid, it gets diverted into a separate container to collect the foamate. The height of the foam column is dependent on the application. The diverted foam is liquefied by collapsing the foam bubbles. This can usually be achieved by mechanical means or by lowering the pressure in the foamate collecting vessel. Foam separators for different types of applications use the basic set up shown in the diagram, but can vary with placements and addition of equipment. Design considerations Additional equipment on the basic form of a foam separator apparatus can be used to achieve other desired effects that suit the type of application, but the underlying process of separation remains the same. The addition of equipment is used to optimize the parameters, enrichment E, or recovery R. Typically, enrichment and recovery are opposing parameters, but there have been some recent studies showing the ability to simultaneously optimize both parameters. The variation of flow rates on the gas input as well as other equipment settings has effects on the optimization of the parameters. The table compares foam separation to other techniques used to separate the protein, α-lactalbumin, from a whey protein solution. pH pH is an important factor in foaming because it will determine if a surfactant will be able to move into the foam phase from bulk liquid phase. The isoelectric point is one factor that must be taken into consideration, when surfactants have neutral charges they are more favorable for adsorption to the liquid-gas interface. pH offers a unique problem for proteins due to the fact that they will denature in pHs that are too high or low. While the isoelectric point is ideal for surfactant adsorption, it has been found that foam is most stable at a pH of 4 and that the foam volume is maximized at pH 10. Surfactants The chain