Filtration of biological sludge by immersed hollow-fiber membranes: influence of initial permeability choice of operating conditions

Recent progress in membrane technology, combined with increasing concern about environment protection, led industrialists and researchers to the development of advanced treatments for domestic wastewater. Membrane bioreactor technology seems to be promising. This study is performed in the context of a regional program for design and optimization of membrane bioreactors for domestic water reuse. We focused on the management of membrane fouling by alternative period of filtration, backflushing, or static state. Moreover, we show how the membrane initial permeability is important in such systems. The experiments were performed on sludge.

All of these preliminary results lead us to propose a panel of operating conditions for the sequenced mode, depending on the membrane permeability. It is especially pointed out that backflushing is more needed for the MF mem- brane than UF, for which a static period should be sufficient for fouling limitation. The second part of the work consisted of checking the previous assessments obtained from the preliminary “continuous” experiments. Reported experiments in sequenced mode confirmed the predicted performances. From a flux point of view, the ones obtained are among the greatest ever reported in the literature. Theses results should be confirmed by experiments on a continuous bioreactor. Considerations on the process profitability are also needed at this step of the study.