The original cost function (A1) for a conventional settling tank is as follows:
This has as variable (A) the total area of the conventional settler in ft2 (square feet). The following relationship was used to express that area as a function of flow:
Where C is the hydraulic head of the settler and a value of (30 m / d) is taken. The transformation is carried out as follows:
Additional modifications to this function correspond to the correction of costs per year, with the CCI ENR index of 9547 of the year 2013, to obtain A3. Then part B2 related to the elasticity index is added. This is done in the same way as explained in the Cost Functions Wiki — General .
According to the above, the function obtained is the following:
