Filtration blocking laws: Revisited

Membrane filtration data are frequently interpreted using membrane blocking laws, with an filtration exponent m=2, 1.5, 1 and 0, corresponding to complete blocking, standard blocking, intermediate blocking and cake filtration, respectively. Complicated filtration models that are based on combined blocking mechanisms have been discussed in the literature. This study presents a general blocking equation that is based on the Hagen-Poisseuille equation, considering the continuous change of the geometric parameters of the membrane pores and those of the interior of the cake (if it exists) with filtrate volume as those adopted in literature. The proposed blocking model summarized the blocking laws that have been proposed in the literature. Based on the proposed model, the filtration exponent m can be regarded as a continuous function of filtrate volume and can be changed during filtration test. Effects of pore shape and size on blocking behavior were discussed. ? 2010 Taiwan Institute of Chemical Engineers.