Larger-Scale Studies

Before reviewing larger-scale studies and applications, we briefly discuss the modes of operation possible in foam flotation and the corresponding details of column design to optimize results. Although mathematical models currently provide excellent simulations of column design and operation, that discussion is beyond the scope of this chapter. The discussion herein is qualitative. 

Column operation is either batch or continuous mode. Flow can be sinqile or countercurrent. For countercurrent systems, there are three rn jor operational modes stripping, enridring, and a combination (see Fig. 17.4-1). 

In the stripping mode, influent liquid is introduced into the foam part of the way up the column and flows countercurrently to the rising foam the section of column above the poim at which the influent is introduced permits foam drainage. In stripping columns, the objective is to reduce the effluent solute concentration to the lowest feasible level, metimes partial recycling of effluent is used to improve solute removals. 

In enriching columns, some of the collapsed foamate is recycled back to the upper section of the column to increase the solute concentration in the foamate as much as possible. 

Another option is the use of baffles. The use of baffles in continuous flow foam columns improves removal efficiency and increases maximum hydraulic loading rates by reducing channeling in the foam and other types of axial dispersion. 

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Guha AK, Majumdar S, and Sirkar KK. A larger-scale study of gas separation by hollow-fiber-contained liquid membrane permeator. JMem Sci, 1991 62(3) 293-307. 

In multi-scale studies, the larger-scale study can be based on a simpler (parsimonious) model, while in the smaller-scale study a more detailed model is required. 

This chapter provides an overview of the various bubble and foam separation techniques. The overview inclndes not only the results of laboratory and larger-scale studies but also tbe mathematical models diet can be employed to optimize removal efficiencies atid predict removal behavior. 

The poor results, in terms of cardiac output, as well as in terms of survivors, found when larger-scale studies were published, initiated the development of what has become known as adjuvants to standard CPR or alternative CPR techniques. These techniques, all based on the apphcation of CPR as CCCR, described by Kouwenhoven et al. [12] in 1960, attempt to improve survival using a variation of the basehne technique. The main line of adjuvants is presented in the order of their initial publication. Their underlying conceptual models are explained. Where possible, human data is referenced. 

In health care, clinical trials are conducted to collect safety and efficacy data for new drugs or devices. Depending on the type of product and the stage of its development, investigators enroll healthy volunteers and/or patients into small pilot studies initially, followed by larger scale studies in patients that often compare the new product with the currently prescribed treatment... 

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