Feasibility assessment of surface water disinfection by ultrafiltration

Ultrafiltration (UF) has been presented as an alternative to chemical disinfection to obtain safe drinking water, for its ability to remove microbiological contamination. Hollow-fiber UF membranes are designed as an effective barrier to microorganisms, for their high manufacturing integrity and for the "potting" method adopted to seal fibers to the feeding/extraction manifold. While the main advantage over chemical disinfection is the drastic reduction of disinfection-by-product (DBP) formation, some chemicals are still required to control fouling and related sanitary risks. This study aims at an up-to-date assessment of UF use for surface water disinfection by compact, minimally-attended, automated plants. A 3.5 m3/h automated UF pilot-plant was run for eight months for drinking quality purification of surface water from Pescia stream. Standard drinking water parameters, as well as specific microbiological parameters (Legionella, Mycobacterium, Adenovirus, Coliphage) and DBP formation were monitored. Final results highlighted that the plant could reach a good removal of bacteria and a significant reduction of viruses. However, the adopted operation/maintenance policies had a strong impact on energy and water consumption, efficacy of bacterium/virus barrier and DBP formation. Hence, an accurate and competent operation, as well as the assistance of chemical disinfection, are still required for safe drinking water production.