4 Membrane process parameters
Video 4 outlines the definitions of flux, pressure, permeability, membrane aeration, recovery and rejection.
Video 4 Membrane process operating parametersVideo player: 4a%20Membrane%20process%20parameters.mp4
Transcript: https://www.open.edu/openlearncreate/mod/page/view.php?id=161927
The equations for flux, pressure, permeability, SADm, SADp, recovery, rejection and concentration factor are as follows:
| Flux, L/(m2h) or LMH | J = Q/A |
| Permeability, LMH/bar | K = J/TMP |
| Recovery, R | Qp/Qf |
| Rejection, r | Cp/Cf |
| Concentration factor, CF | 1/(1+R), when r = 100% |
| Specific aeration demand for membrane air scouring, Nm3/m2 membrane area, SADm | Qa/A |
| Specific aeration demand for membrane air scouring, Nm3/m3 permeate, Q'a,m | SADm/J', J' in units of m3/(m2h) |
where
TMP is the transmembrane pressure in bars, 1 bar = 100,000 Pa
Cp and Qp are the permeate flow and concentration
Qf and Cf are the feed flow and concentration
Qa is the air scour rate in Nm3/hr, Nm3 = 'normal cubic metres', 'normal' being standard temperature and pressure taken as 20°C and 1 atmosphere pressure (~1 bar).
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Question 7: Using the above equations, calculate the flux, in both LMH and SI units, for a permeate flow of 150 m3/hr through 200 membrane modules each having an area of 30 m2. |
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Question 8: If the permeability is 80 LMH/bar, what is the TMP? |
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Question 9: If the feed flow is 43 L/s, what is the recovery? |
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Question 10: Calculate the specific aeration demand in SADm = Aeration rate/area = 2400/(200 x 30) = 0.40 Nm3/h per m2. |
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You're now able to calculate the key parameters impacting on specific energy consumption in membrane processes specifically. Next we'll look at the immersed membrane bioreactor (iMBR) process.
You can now move to Section 5 The immersed membrane bioreactor process