ARIMA	Autoregressive integrated moving average
CP	Concentration polarisation
ln	natural logarithm
Pe	Boundary layer Peclet number
TMP	Transmembrane Pressure
UF	Ultrafiltration
A	area of membrane
C	concentration
D	diffusivity
F	net driving force
J or J(t)	volumetric flux
Kn	constant dependent upon the mode of blockage (Equation (11))
k	boundary layer mass transfer coefficient $\left(=D/\delta \right)$
kn	constant dependent upon the mode of blockage (Equation (9))
n	index characteristic of a particular mode of blocking
Rf	foulant resistance (m−1)
Rm	hydraulic resistance of the membrane (m–1)
Rt	overall resistance (m−1)
t	time
V	filtrate volume
v	specific volume $(=V/A)$
$\delta$	thickness of mass transfer boundary layer
μ	viscosity
${\mu }_p$	viscosity of the permeate
ΔP	transmembrane pressure difference
$\Delta \pi$	osmotic pressure difference across the membrane ($={\pi }_m-{\pi }_p)$