Development of a new high porosity ceramic membrane for the treatment of bilge water

Bilge waters with different oil-emulsion droplet sizes can be treated successfully using ultrafiltration processes with ceramic membranes. The structure of these membranes has been designed to obtain high permeate fluxes and increase the efficiency of the process. Membranes with very high porosity (about 70%) have been obtained. Using water permeation experiments, it was shown that the permeate fluxes obtained using this membrane configuration are higher when compared to membranes with similar structural characteristics. The kind of the fouling process (internal or external) was evaluated to understand the filtration mechanisms of membrane. These phenomena are very affected by the transmembrane pressure used in each case. Using a multilayer system with a membrane of 6 nm and transmembrane pressures between 0.2 and 0.5 MPa, the oil content in the permeate fluxes can be decreased to below 15 ppm. For the elimination of internal fouling, a membrane regeneration process is proposed. This process consists of a thermal treatment to volatilize the oil droplets deposited on the pore walls of membrane. Using N2 permeation measurements, an absence of any residue into the membrane and the stability of the membrane structure after the thermal treatment were demonstrated.