104 M.J. Lewis 04 叶2456}。。 Concentration factor Fig. 4. 3. Change in rejection during UF:(a)glucosinolates; ( b)total solids; (c)protein f= Rlogf=log(cc/cF R= log(cc/cF)/logf This expression for the rejection is effectively an average rejection(Ray) for the process Therefore Rav =log(cc/cF (4.11) Estimation of average rejection is based upon knowing the initial and final concentrations and the concentration factor It is interesting to note that, in this case, the membrane rejection can be determined without sampling the permeate herefore the average rejection is defined as the rejection value which would provide the same yield which was actually found in the process, even though the instantaneou rejection may have been changing throughout 4.2.4 Practical rejection data Although some of the proposed models predict how rejection will be influenced by operating conditions and pH, there is often little agreement between theory and practice0.4 0.2 0 - - IIIIIIIII