(159d) A Methodology for the Evaluation of Membrane Robustness and Lifetime

After determining whether a membrane is able to conduct a needed separation, economic factors are normally key drivers in the selection of a UF or MF membrane solution. Typically this would include the number of modules required, required pressures and the associated energy costs, as well as chemical costs for any required chemical dosing and cleaning. As a result much attention is paid to a membrane’s surface chemistry, charge, and roughness (cleanability), the feed side fluid dynamics (sustainable flux/number of elements), and the structure and morphology of the separating layer (permeance and operating pressure). As a result of this, introductions of new membrane products often feature deep dives into these well-travelled aspects of membrane science. Missing in this analysis is a discussion of membrane lifetime. This may be partly attributable to the fact that each system ends up seeing a unique combination of conditions and stresses that can lead to a multitude of potential failure modes.

This paper will present a process that can be used to validate membrane lifetime for a new membrane product without known end of life examples. Application of this method to a new ceramic ultrafiltration module will be discussed including the identification of specific criteria used to quantify the end of life point, determination of potential stresses that could result in failure, and development and execution of accelerated tests to probe each potential stress as well interactions amongst the stresses. Also to be discussed are models relating the accelerated conditions with conditions to be experienced in normal operation. Stresses to be discussed include temperature, pressure, vibration, and chemical exposure.