Modeling long-term subcritical filtration of model EPS solutions

Using alginate as a model extracellular polymeric substance, a two-stage TMP profile, with a slow rise followed by a rapid rise, similar to that typically observed with membrane bioreactor effluents was observed during long term filtration. The alginate transmission profile supported the concept of flux redistribution among open pores as a cause of the two stage fouling profiles. A model based on fouling mechanisms was developed to take into account pore plugging of larger pores and flow redistribution among other pores as a function of time. A critical pore size is used in the model for transmission time determination. Using the pore size distribution of polyvinylidenefluoride membranes, the model is able to fit the experimental results with two adjustable parameters. Both parameters can be correlated to the average imposed flux.