Alternative Water Removal Technologies

There is an extensive literature devoted to the preparation of oxide and mixed-oxide catalysts. These compounds are often derived from hydroxides, though alternative processes are available, e.g., calcination of metals, oxalates etc. Some of the studies referred to above were undertaken to add to the understanding of the textural changes which accompany water removal during the preparation of catalytically-active phases of technological importance. Heating of mixed hydroxides, prepared by concurrent precipitation, yields spinels and other specific phases, including solid solutions, at lower temperatures than is possible with less-intimate mixtures. The... 

Different process technology alternatives for removal of the low-boiling fraction were computer-simulated. Direct discharge of water vapour steam offers the most favourable option which protects the product. 

The prevacuum technique, as its name implies, eliminates air by creating a vacuum. This procedure faciUtates steam penetration and permits more rapid steam penetration. Consequendy this results in shorter cycle times. Prevacuum cycles employ either a vacuum pump/steam (or air) ejector combination to reduce air residuals in the chamber or rely on the pulse-vacuum technique of alternating steam injection and evacuation until the air residuals have been removed. Pulse-vacuum techniques are generally more economical vacuum pumps or vacuum-pump—condenser combinations may be employed. The vacuum pumps used in these systems are water-seal or water-ring types, because of the problems created by mixing oil and steam. Prevacuum cycles are used for fabric loads and wrapped or unwrapped instmments (see Vacuum technology). 

The results of the EPA SITE demonstration also showed that the cost of methane necessary to support trichloroethylene biodegradation is not excessive in relation to the costs of other technologies available for the removal of trichloroethylene from water. Thus, the Biotrol system may prove to be a cost-effective alternative to more traditional groundwater remediation technologies. 

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