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Cost Function for granular aluminum sulfate dosing

Cost Functions

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

Función de costo para dosificación de sulfato de aluminio gr (1)

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

Función de costo para dosificación de sulfato de aluminio gr (2)

Like the other coagulant dosage equations, the dosage of aluminum sulfate depends on the quality of the water. Three functions are then proposed, for three levels of raw water quality:

Good 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:

Función de costo para dosificación de sulfato de aluminio gr (3)

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 function obtained is the following:

Función de costo para dosificación de sulfato de aluminio gr (4)

Normal 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

Función de costo para dosificación de sulfato de aluminio gr (5)

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 the 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 Wiki. 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:

Función de costo para dosificación de sulfato de aluminio gr (6)

Low to very Low quality

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

Función de costo para dosificación de sulfato de aluminio gr (7)

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:

Función de costo para dosificación de sulfato de aluminio gr (8)

 

Bibliography

  1. Preliminary Cost Estimation Models for Construction, Operation, and Maintenance of Water Treatment Plants Jwala R. Sharma, Ph.D., M.ASCE; Mohammad Najafi, Ph.D., P.E., F.ASCE; and Syed R. Qasim, Ph.D., P.E., M.ASCE 2013

    Reliable cost estimation of construction, operation, and maintenance (O&M) of water treatment plants is essential for project planning and design. The authors have developed construction and O&M cost models for different unit operations and processes involved in water treatment plants. This paper presents the use of a single cost index to further update construction and O&M costs.

References

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