CFD simulations of flow fields during ultrafiltration: Effects of hydrodynamic strain rates with and without a particle cake layer on the permeation of mobile genetic elements

Abstract

Membrane ultrafiltration (UF) combined with inline dosing of powdered activated carbon (PAC) are popular hybrid processes for water reclamation. However, hydrodynamic forces can allow mobile genetic elements (MGEs) that are larger than the membrane pore size to penetrate through UF membranes. The flow fields in the feed channel of a dead-end UF membrane module were modelled using computational fluid dynamics (CFD) in order to analyze shear and elongational strain rates and associated potential hydrodynamic effects by a PAC particle layer on MGE retention. The most significant magnitudes of strain rates occurred within a distance of tens of nanometers from the membrane surface, meaning that this is where significant deformation of MGEs occurs. Since flow fields were not considerably altered at the membrane surface, the presence of the PAC particle layer was expected to have a negligible impact on the permeation of MGEs through UF membrane pores.