Membrane process, variables

The three streams and associated variables of the RO membrane process are shown in Figure 2b the feed the product stream, called the permeate and the concentrated reject stream, called the concentrate or retentate. The water flow through the membrane is reported in terms of water flux, J. ... 

Factors affecting RO membrane separations and water flux include feed variables such as solute concentration, temperature, pH, and pretreatment requirements membrane variables such as polymer type, module geometry, and module arrangement and process variables such as feed flow rate, operating time and pressure, and water recovery. 

The amount of limonin incorporated into the juice is influenced by a number of juice processing variables. Factors such as the maceration of albedo, central vascular bundle and carpellary membranes, the time of contact between the rag and the juice, and the amount of pulp incorporated into the final juice product are known to influence juice limonin content. The uneven distribution of XIV in the various tissues of the fruit (Table VII) is largely responsible for the effects of processing variables (33). 

In general, all elements of the mass transfer matrix depend on the process variables, and in particular on the vapor phase composition. The mass transfer mechanisms in membranes can be rather complicated. However, for the conceptual analysis of the considered membrane process, it is not advantageous to go into the details of mass transport. Therefore, in the following the effective binary mass transfer coefficients k,j are assumed to be constants. 

Among the disadvantages, the fouling and degradation of membrane surfaces of the polymeric membrane systems under adverse chemical and thermal conditions are often cited. However, these problems may be partly overcome by proper pretreatment of the effluents, optimizing the process variables and selecting suitable membrane materials. The radioactive wastes most suited for membrane separation are characterized by chemically insignificant amounts of radionuclides and small amounts (few hundred parts per rnilhon) of inactive ionic species. 

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