Cost function for liquid aluminum sulfate dosing:

The original cost function (A1) for the aluminum sulfate dosage is as follows:

This variable (x) is the dosage capacity of liquid aluminum sulfate in lb / h (Pounds per hour). To convert it into a function of the flow rate, the following relationship was used:

Like the other coagulant dosage equations, the dosage of aluminum sulfate depends on the category. Therefore, there are three different functions for this equation as follows:

High quality

For this water quality, a usual dose of 1.1 mg / L is taken. With this data, the following replacement of the variables of the equation is proposed:

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 a similar way to that explained in the Cost Functions Wiki — General. In this case, the reference quality of factor B2 changes, in this case corresponding to the maximum limits of good quality, being 4.4 mg / L for sediments and 10 mg / L for nitrogen.

With these data, the following is the function obtained:

Average quality

For this water quality, a usual dose of 14 mg / L is taken. With this, the following replacement of the variables of the equation is proposed:

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 a similar way to that explained in the Cost Functions Wiki — General. In this case, the reference quality of factor B2 changes, in this case corresponding to the maximum limits of regular quality, being 56 mg / L for sediments and 20 mg / L for nitrogen.

With these data, the following is the function obtained:

Low to very low quality

For this water quality, a usual dose of 50.8 mg / L is taken. With this data, the following replacement of the variables of the equation is proposed:

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 a similar way to that explained in the Cost Functions Wiki — General. In this case, the reference quality of factor B2 changes, in this case corresponding to the maximum limits of regular quality, being 200 mg / L for sediments and 30 mg / L for nitrogen.

Therefore, the function obtained is the following:

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