B c D H kfp kfr L M N p Q Qfp R T TCF Tref vw vs w WHP $W_{BP}^{ERD}$ x t	salt transport coefficient (m/s) concentration (mg/L) diffusion coefficient of solute (m2/s) channel height (m) colloidal fouling potential coefficient friction coefficient channel length (m) molecular weight (g/mol) total number of units pressure (bar) volumetric flow rate (m3/d) volumetric flow rate through the pump (m3/d) membrane resistance (m−1) temperature (K) temperature correction factor reference temperature (K) water flux (m3/m2 s) salt flux (kg/m2 s) membrane channel width (m) work done by the high-pressure pump (kW) work done by the booster pump (kW) distance along the membrane channel operation period
Greek symbols
μ π ξ τ ${\eta }_{HP}$ ${\eta }_{VFD}$ ${\eta }_{BP}$ ${\eta }_{ERD}$	viscosity (Pa s) osmotic pressure (bar) dummy variable for the integration of distance x dummy variable for the integration of time t efficiency of high-pressure pump (%) efficiency of variable frequency drive (%) efficiency of booster pump (%) efficiency of energy recovery device (%)
Subscripts
A B BP f HP m PV p TRN t s w	water permeability salt permeability booster pump feed high-pressure pump membrane wall pressure vessel permeate train total salt water