Membrane operating conditions

The jfipervap term in Equation (9.2) and Equation (9.5) can be derived in terms of /3evap, membrane permeabilities, and membrane operating conditions using the standard solution-diffusion model from Chapter 2. The membrane fluxes can be written as... 

The permeate and concentrate flows, and their respective conductivities, are depicted in Figure 41.10 for Toray membrane. Operating conditions for the Osmonics membrane... 

Cycle time clean by backwashing with permeate every 6, 24,170, 360, 1000 h (depending on the criteria, the membrane, operating conditions, and the amount of pretreatment) example, 8 h on and 1 to 2 h off to clean or short pulses every 150 to 300 s so that steady-state flux operation is never achieved. 

In principle, all atomically clean transition metals will adsorb and dissociate molecular hydrogen. For noble metals such as palladium, which do not readily form stable oxides, carbides and nitrides under membrane operating conditions, no additional catalyst or protective layer is normally required. However, for the less noble metals, and especially for highly reactive metals including Nb, Ta, H, V and Zr, surface layers of oxides, carbides and nitrides will rapidly form and poison... 

Membrane module performance can to some degree be predicted as a function of operating parameters and feedwater characteristics. Calculation methods [40,41] exist for various membrane operating conditions, but computer modeling programs available from the membrane manufacturers have largely superseded these. These programs predict the performance of a membrane plant based on feedwater analysis and performance requirements. 

Criticism of membrane integration has to be carefully faced. If the selective membrane is directly integrated in the reaction environment, coupling catalyst and membrane operating conditions leads to the necessity to define a compromise... 

On the other hand, the membrane can be integrated externally, by an architecture which foresees reaction and separation steps in series. In this way, catalyst and membrane operating conditions are independent and their optimal operating conditions can be defined separately, but the membrane integration benefits are reduced. 

There are several risk factors that are also applicable to non-biofouling membrane operating conditions. These should be kept in mind when operating any membrane system ... 

J.T. Keating, Understanding Membrane Operating Conditions. In T.C. Wellington (ed.) Modem Chlor-Alkali Technology, Vol. 5, Elsevier Applied Science, London, (1992), p. 69. 

S. Banetjee, Understanding Membrane Operating Conditions, In ELTECH Chlorine/Chlorate Seminar, ELTECH Systems Corp., Cleveland, OH, Sept. 1999. 

Average H2 flux for different membrane operating conditions and configurations. 

Brandhuber, P. Amy, G. (2001) Arsenic removal by charged ultrafiltration membrane - influences of membrane operating conditions and water quality on arsenic rejection. Desalination, 140 (1), 1 -14. 

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