Application of low pressure membranes in public drinking water supply for particle removal has been rapidly increased in recent years. Among numerous innovations in this sector ceramic membranes are attracting an increasing interest. Ceramic membranes are considered as resistant to mechanical, chemical and thermal stress. They have a high porosity and a hydrophilic surface. These properties may open various fields for applications in water treatment, such as the treatment of residuals from drinking water production or the direct treatment of surface waters.

Objective of this study was to examine different ceramic membrane materials, pore sizes and feed waters with limited use of chemicals for treatment of backwash waters from a full scale water treatment plant.

The study was conducted in pilot scale. The pilot plant was planned to operate fully automated in cross-flow as well as in dead-end mode. Online sensors and data loggers were installed to monitor flow, pressure and temperature. The construction of the pilot plant allowed the use of various ceramic membrane elements, such as different cut-offs and channel diameters.

Membranes tested were compared concerning the increase of membrane resistance during chemical free operation for one backwash water type, collected from full scale filters. Al2O3-microfiltration membranes showed comparable total membrane resistances and resistances of fouling layers.The total membrane resistance of Al2O3-ultrafiltration membrane is somewhat higher in relation to the microfiltration membrane due to the smaller cut-off of the ultrafiltration membrane. The Al2O3-ultrafiltration membrane had about the same resistance of fouling layer compared to the Al2O3-microfiltration membranes.

Results imply that total membrane resistance was more influenced by backwash water type and operation compared to membrane type for the waters tested. Plant optimization is therefore not limited to changing the membrane type.