ANOMALOUS FILTRATION

Filtration is a very common process in living cells, in intact organis ms, in research laboratories and in industrial plants. It is usually t reated by scientists and engineers as a useful and convenient techniqu e rather than as a process of intrinsic interest. The commonness of fi ltration frequently misleads professionals to the view that it is a fu lly clarified, simple process which is sufficiently described by Poise ulle's law and its derivatives, that for some purposes ad hoc may be s upplemented with empirical corrections. This review shows that filtrat ion is actually a complicated process, the nature of which can now be better understood in the light of recent progress in the fields of non -linear dynamics, irreversible thermodynamics and the fractal descript ion of nature. These advances permit the replacement of many empirical corrections with terms derived from realistic models provided by the new insights and offer promising new opportunities for research.