Impact of operating conditions on permeate flux and process economics for cross flow ceramic membrane ultrafiltration of surface water

Ceramic materials for microfiltration and ultrafiltration have a number of potential advantages over polymeric materials including chemical and thermal stability, physical strength, and a longer operational life. In this study the effects of tubular ceramic membrane hydrodynamic conditions (cross flow velocity and transmembrane pressure), in-line coagulation, and backwash flow rate on permeate flux using one type of 0.01 μm ceramic membrane with two different channel configurations were investigated. Factorial experimental design was used to construct a controlled set of experiments in which the effect of varying the operating parameters was measured. Flux decline and moving average flux were the derived response variables. Response surface methodology was then used to evaluate the experimental design results to find the operating conditions that resulted in either the least amount of flux decline or the highest moving average flux. A life cycle cost analysis determined that a plant designed and operated to achieve minimum flux decline resulted in a higher total plant cost than a plant designed and operated at more aggressive filtration conditions, which produced the higher moving average flux and more flux decline. This is due to the high material cost for a ceramic membrane.

► We evaluate ceramic membrane flux at different operating conditions.
► Cost is calculated based on operating conditions, flux, and required membrane area.
► Minimizing membrane area, by maximizing flux, results in the lowest total plant cost.
► Minimizing flux decline results in a higher total plant cost.