Evaluation of Permeate Flux Rate and Membrane Fouling in Dead-End Microfiltration of Primary Sewage Effluent

Abstract

Dead-end microfiltration was used to evaluate the permeate flux and fouling mechanisms by primary sewage effluent from a local wastewater treatment plant for seven polymeric membranes ranging in pore size from 0.2 to 0.8 µm. Permeate flux rates were evaluated during separate filtration runs at transmembrane pressures of 1.03 and 2.06 bar and during a periodic increase in filtration pressure from 1.03 to 4.14 bar in a single run. The steady-state permeate flux rates were very similar for all pressures and pore sizes, and there was little benefit from increasing the pressure during a microfiltration run. Hydrophobic membranes generally gave lower initial flux rates than hydrophilic membranes of the same pore size. This study suggests that the permeate flux reduction during a filtration run was mostly due to the cake buildup on the membrane surface, while the internal fouling of the membrane pores was limited.