Mechanical analyses of hollow-fibre water treatment membranes

The long-term durability of water treatment membranes under working pressures is considered to be vital; however, there has not been a comprehensive analysis framework for that purpose. We therefore carry out a series of mechanical analyses for the hollow fibre water treatment systems under filtration and backwashing conditions. A series of quasi-static analyses are performed initially; and the stress conditions are determined under the operational filtration and backwashing pressures. Afterwards, the viscoelastic effects are invoked for the long-term deformation analysis of the hollow fibre membranes. Both quasi-static and viscoelastic analyses are performed by a commercial finite element package, ANSYS. The mechanical fatigue life predictions are then carried out considering the stress values from the quasi-static analyses and the long-term deformations from the viscoelastic analyses. Findings from the analyses recommend that the impact of the long-term viscous deformations on the fatigue lives are less severe compared to that of backwashing. The increase of the backwashing and filtration pressure has been found to be reducing the membrane lives significantly.