1. Fw = water flux rate (liter/m2-hr)

3. Fs = flux of solute species, mg/m2-hr

4. Computing osmotic pressure:

5. (Note: 1 bar = 14.5 psi)

6. Typical values for kw and ks:
ks: 5 x10-4 m/hr

7. Units can create serious problems for RO design calculations
Units can create serious problems for RO design calculations. For example
In the text Wastewater Engineering by Metcalf and Eddy in Chapter 11.6 the following example (Ex. 11.5) is used to show how to calculate water and solute flux rates. The water flux eqn. used is:

9. The problem states:
Then calculations proceed as:

10. force
mass
force 3

11. Obviously the dimensions on kw are incorrect.
Note that the relationship between kg (force) and
kg (mass) is given by Newton’s law:
F = m x g where g = m/sec2
F = (kg force), m = (kg mass)