Therefore, a sensitivity analysis was performed in order to
check the robustness of the results even for widely different values
of the unit cost entries. A Monte Carlo approach was adopted. The
total annual cost was expressed as a function of 6 stochastic variables:
the total installed costs of the ESP and the FF device, the purchase
costs of lime and bicarbonate, the disposal cost of residues
and the cost of recovering brine from SBW. A typical distribution
of probability (a symmetric beta distribution with a = b = 2) was
associated to each variable, within the respective intervals of variation
reported in Table 7. The mean values were set equal to the
base values discussed above and used in the assessment, while