A membrane is fouled with a layer of bacteria (a bioflim). The water permeability of the biofilm is 2 x 10^-12 mol m s^-1 m^-2 atm^-1 and is 21 μm thick. The membrane is 52 μm thick with a water permeability of 1 x 10^-12 mol m s^-1 m^-2 atm^-1. Neglect the convective mass transfer resistance as they are very small.

The partial pressure of water of one side is 200 kPa and 101 kPa on the other.

Calculate the total mass flux of water through the combined membrane and biofilm in mol m^-2 s^-1 (3 SF) eg 1.67E-8.

Conversion 1 atm = 1.01325 x 10⁵ Pa