Supplementary material Spatial heterogeneity of biofouling under different cross-flow velocities in reverse osmosis membrane systems N.M. Farhata*, M. Staalb, Sz.S. Bucsa, M.C.M. Van Loosdrechtb, J.S. Vrouwenveldera,b,c a
King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia b Delft University of Technology, Faculty of Applied Sciences, Department of Biotechnology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands c Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA, Leeuwarden, The Netherlands * Corresponding author: Tel. +966562604415, e-mail:
[email protected], King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia
Journal of Membrane Science http://dx.doi.org/10.1016/j.memsci.2016.08.065
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B
Inlet - cross-flow velocity 0.16 m.s-1
Outlet - cross-flow velocity 0.16 m.s-1
0.18
0.18
0.16
0.16
0.14
0.14
ODR (mg.L-1.s-1)
ODR (mg.L-1.s-1)
A
0.12 0.1 0.08 0.06
0.12 0.1 0.08 0.06
0.04
0.04
0.02
0.02
0
0 1
3 4 Time (days)
5
6
1
D
Inlet - cross-flow velocity 0.12 m.s-1
0.18
0.16
0.16
0.14
0.14
0.12 0.1 0.08 0.06
6
0.1
0.06 0.04 0.02 0
2
3 4 Time (days)
5
6
1
F
Inlet - cross-flow velocity 0.08 m.s-1
0.18
0.16
0.16
0.14
0.14
0.12 0.1 0.08 0.06
2
3 4 Time (days)
5
6
Outlet - cross-flow velocity 0.08 m.s-1
0.18
ODR (mg.L-1.s-1)
ODR (mg.L-1.s-1)
5
0.08
0.02 1
E
3 4 Time (days)
0.12
0.04
0
2
Outlet - cross-flow velocity 0.12 m.s-1
0.18
ODR (mg.L-1.s-1)
ODR (mg.L-1.s-1)
C
2
0.12 0.1 0.08 0.06
0.04
0.04
0.02
0.02 0
0 1
2
3 4 Time (days)
5
6
1
2
3 4 Time (days)
5
6
Figure S1– Average stop-flow oxygen decrease rate (ODR) (mg·L-1·s-1) at two positions (inlet and outlet of the flow cell) monitored in time (days 1-5) at three cross-flow velocities (A, B: 0.16 m·s-1; C, D: 0.12 m·s-1; E, F: 0.08 m·s-1).
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-2
-1
Stop-flow ODR per unit area [g.m .d ]
10 9
5
Inlet Outlet
8 7 6 5
5
4
4
5
3
3
4 4
2 1 0
3
3 1
2
0.16
1
2 1
0.12
2
0.08 -1
Cross-flow velocity [m.s ] Figure S2– Average stop-flow oxygen decrease rate (ODR) per unit area (g·m-2·d-1) at two positions (inlet and outlet of the flow cell) monitored in time (days 1-5) at three cross-flow velocities (0.16, 0.12, and 0.08 m·s-1).
Converting the flux as measured in mg.L-1.s-1 (Figure 2 in the manuscript) to a flux per surface area of membrane requires a known water volume. Since we only know the initial water volume, this value has been used for the calculations. Water volume decreases with time as biofilm develops in the MFS, therefore, the calculated ODRs per unit area will be slightly more underestimated with increasing time. The actual oxygen flux should ideally be expressed per biofilm surface area instead of the membrane surface area.
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Figure S3–Oxygen concentration images (mg·L-1) on day five taken one minute after stopping the flow at the inlet and outlet positions of the flow cell for three cross-flow velocities (0.16, 0.12, 0.08 m·s-1). Flow direction is from left to right. Imaged area is 3.8 cm × 2.5 cm.
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Figure S4– Cross-section locations along the length of the inlet and outlet for the oxygen concentration profiles. Area 3.8 cm × 2.5 cm.
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Flow direction MFS outlet
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7
6
6
Oxygen concentration (mg/L)
Oxygen concentration (mg/L)
MFS inlet
5 4 3
0.5 cm
2 1
5 4 3 2 1
0.16 m/s
0.16 m/s 0
0 0
0.5
1
1.5
2
2.5
0
0.5
7
7
6
6
Oxygen concentration (mg/L)
Oxygen concentration (mg/L)
Distance (cm)
5 4 3
1.0 cm
2 1
1.5 Distance (cm)
2
2.5
5 4 3 2 1 0.12 m/s
0.12 m/s
0 0
0.5
1 1.5 Distance (cm)
2
0
2.5
0
7
7
6
6
Oxygen concentration (mg/L)
Oxygen concentration (mg/L)
1
5 4 3 2 1
0.5
1 1.5 Distance (cm)
2
2.5
5 4 3 2 1
0.08 m/s
0 0
0.5
1 1.5 Distance (cm)
2
2.5
0.08 m/s 0 0
0.5
1 1.5 Distance (cm)
2
2.5
Figure S5– Oxygen concentration (mg·L-1) profile along the length (cm) of the inlet and outlet for the different cross-flow velocities.
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1
6
Day Day Day Day Day
2
-1
Average Oxygen Concentration [mgL ]
7
1 2 3 4 5
5
3 4
3
4
2
1
5 0 0
1
2
3
4
5
Time [minutes]
6
7
8
9
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Figure S6: Stop-flow plot: Average oxygen concentration (mg·L-1) decrease with time on day 1-5 due to a 10 minute water flow interruption of the MFS. (Figure taken from Farhat et al. 2015),[36].
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