*2.2. Parameter Estimation*

Based on the above equations a number of parameters need to be fit in order to model the performance of the spiral wound reverse osmosis membrane for the prediction of salt and boron removal. Hence, in this study we suggest the sequential procedure of parameter fitting steps as given in Figure 2. Sundaramoorthy et al. [30,31] suggested procedures for steps 1, 2, and 4 where they suggest linear fitting for steps 1 and 2 and a least-squares (presumably nonlinear) fitting for step 4. Additionally, in step 2 they assumed that *A*<sup>w</sup> and *B*<sup>S</sup> are fixed and do not change with temperature.

In the procedure shown in Figure 2, the first step should be to estimate pressure drop. Subsequently the water and salt transport coefficients *A*<sup>w</sup> and *B*<sup>S</sup> should be estimated for each inlet temperature such that the temperature dependence can be predicted. Steps 3 and 4 are independent of each other but both rely on parameters fitted in steps 1 and 2. All of these steps can be realized through linear fitting using experimentally measured values.

**Figure 2.** Parameter estimation steps for a spiral wound reverse osmosis desalination membrane.
