Direct capillary nanofiltration for ground water and surface water treatment

Capillary nanofiltration is a new concept in membrane filtration. This technique combines the advantages of the good water quality obtained from nanofiltration membranes with the easy hydraulic cleaning of capillary membranes. Direct capillary nanofiltration can be used to treat ground water or surface water without pre-treatment. At the Delft University of Technology several MSc-thesis projects have been carried out on this subject. This paper will describe some results of these studies. A model based on a mass balance to predict the flux of a capillary nanofiltration installation treating groundwater is proposed. In this model the only resistance taken into account is the concentration polarisation. Also a model to predict the flux when treating surface water has been developed. This model takes into account the resistance due to cake filtration.