Symbol/Abbr.	Description
µ	Viscosity (in m2·pa·s−1)
a	Area (in m2)
BW	Brackish water
CE	Circular Economy
CF	Carbon footprint (in kg CO2-eq)
CFC	Chlorofluorocarbon
Cl-	Chloride
dH	Hydraulic diameter (in mm)
Ef	Efficiency factor
EoL	End-of-life
ERD	Energy Recovery Device
EU	European Union
g	Gravity force
GD	Gravity-driven
h	Hours
i	Van ’t Hoff index
ILCD	International Life Cycle Data system
Imp	Environmental impact (in kg CO2-eq)
Inf.	Infinite
IPCC	Intergovernmental Panel on Climate Change
ISO	International Standard Organization
L	Permeability (in L·m−2·h−1·bar−1)
L (unit)	Litre
LCA	Life Cycle Assessment
LR	Permeability ratio
m	Metre
M	Molarity
n	Number of modules
Na+	Sodium ion
NaClO	Sodium hypochlorite
NF	Nanofiltration
NPD	Net Pressure Driven (in bar)
ppm	Parts per million
Pr	Pressure (in bar)
Prl	Pressure loss (in bar)
PV	Pressure vessel
Q	Flow (in m3·h−1)
R	Ideal gas constant
Re	Reynolds number
r-NF	Recycled nanofiltration
RO	Reverse osmosis
SEC	Specific energy consumption (in kwh·m−3)
SL	Service Life (in years)
SLR	Service life ratio
SW	Seawater
T	Temperature (in K)
TRL	Technology Readiness Level
UF	Ultrafiltration
v	Velocity (in m·s−1)
ν	Kinematic viscosity
vs.	Versus
WR	Water recovery rate
П	Osmotic pressure (in bar)
Subscript
Subscript	Description
c	Relative to new commercial produced membranes
conc	Relative to concentrated water flow
e	Relative to energy
in	Relative to inlet water flow
pr	Relative to product water flow
r	Relative to recycled membranes
rep	Relative to replacement activity
total	Relative to the total of the system