High frequency reverse filtration was evaluated while microfiltering a bentonite suspension, biologically treated wastewater and an activated sludge suspension through a 0.2 μm tubular ceramic membrane. Better results were obtained with a conventional internal layer filtration element than with an external skin membrane. However the technique was efficient in enhancing the permeate flux solely with the bentonite suspension. In the other cases, the flux was the same as in conventional cross-flow operation. Such a failure cannot be exclusively attributed to chemical interactions with the membrane since the permeate flux increased linearly with cross-flow velocity for all suspensions in conventional operation. Much research is then required to establish the technique applicability.

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