Table 1 Membrane characteristics taken from the producers’ factsheets, testing conditions of the membrane according to the fact sheets (n.s.) for not specified and the calculated Reynolds numbers according to the flow-through velocity for each membrane

NMWCO (g/mol)

150–300

ns

200

ns

ns

ns

Minimum pH (–)

ns

ns

0

3

2

2

2

Maximum pH (–)

ns

ns

14

10

11

11

11

Maximum temperature (°C)

50

50

95

45

40

45

45

Maximum pressure (bar)

41.4

41.5

40

41

41

41

69

Active area (m²)

1.6

1.7

1.8

2.6

2.6

2.6

2.8

Feed spacer thickness (mm)

1.27

1.27

1.1

ns

ns

0.7

ns

Permeate flow rate (m³/d)

1.3

1.7

1.728

3.5

2.3

3.2

2.6

Salt rejection (%)

98

96

80–95

98

90

99.5

99.4

Substance (–)

MgSO₄

MgSO₄

Na₂SO₄

MgSO₄

MgSO₄

NaCl

NaCl

Concentration (ppm)

2.000

2.000

ns

2.000

2.000

2.000

32.000

Temperature (°C)

25

25

20

25

25

25

25

Duration (h)

24

24

ns

ns

ns

ns

ns

Variation (± X %)

25

25

ns

ns

ns

ns

ns

Recovery (%)

15

15

ns

15

15

15

8

Pressure (bar)

7.6

7.6

40

8.9

5

15.5

55

Permeate flux (m³/d)

1.3

1.7

1.728

3.5

2.3

3.2

2.6

Membrane width (m)

1.57

1.67

1.77

2.56

2.56

2.56

2.76

Feed spacer thickness (mm)

1.27

1.27

1.1

0.9

0.9

0.7

0.9

(m)

0.001

0.001

0.001

0.001

0.001

0.001

0.001

Feed spacer area (m²)

0.002

0.002

0.002

0.002

0.002

0.002

0.002

Circular area diameter (m)

0.050

0.052

0.050

0.054

0.054

0.048

0.056

Flow velocity (m/s)

0.042

0.039

0.043

0.036

0.036

0.047

0.034

Reynolds number (–)

2624

2546

2659

2445

2445

2773

2357

Friction losses (–)

0.046

0.047

0.046

0.047

0.047

0.045

0.048

B (–)

0.939

0.920

0.9472

0.896

0.896

0.974

0.874