Direct capillary nanofiltration for surface water

Capillary nanofiltration (NF) enables raw water to be treated in a single step to produce high-quality permeate. The permeate can be used as process water for industry. Trial studies show that a stable operation is achievable using capillary NF without pre-treatment (in other words direct NF), that the technique saves energy, that there is a low use of chemicals and that the permeate is of a high quality. The capillary NF membrane module combines the favourable cleaning properties of capillary ultrafiltration membranes with the favourable separation properties of NF membranes in terms of the removal of bacteria, viruses, colour, hardness and pesticides. This study describes both the technical as economical backgrounds of the application of direct capillary NF.