where Jw (m3 s−1 m−2
) is the pure water flux, ΔP (Pa) is the
transmembrane pressure applied and μw (Pa s−1
) is the dynamic
viscosity of water.
Then, resistance created by fouling and/or polarization (Ra) during
roselle extract filtration was calculated as the difference between total
resistance (Rt) obtained during the filtration experiment and
membrane resistance (Rm):