Clarifier Costing Method

There are three classes of clarifier costing types (circular, rectangular, and primary), each with their own parameters, variables, and costing relationships. The default configuration is a circular clarifier, so users must manually change the clarifier type if they wish to invoke the costing method for rectangular or primary clarifiers.

Costing Method Parameters

The following parameters are constructed for the unit on the FlowsheetCostingBlock (e.g., m.fs.costing.clarifier) when applying the cost_clarifier costing method in the watertap_costing_package:

Description	Symbol	Parameter Name	Default Value	Units
Circular clarifier
Capital cost A parameter \(^1\)	\(A_{circular}\)	construction_a_parameter	-6e-4	\(\text{USD}_{2011}\text{/ft}^4\)
Capital cost B parameter \(^1\)	\(B_{circular}\)	construction_b_parameter	98.952	\(\text{USD}_{2011}\text{/ft}^2\)
Capital cost C parameter \(^1\)	\(C_{circular}\)	construction_c_parameter	191806	\(\text{USD}_{2011}\)
Rectangular clarifier
Capital cost A parameter \(^1\)	\(A_{rectangular}\)	construction_a_parameter	-2.9e-3	\(\text{USD}_{2011}\text{/ft}^4\)
Capital cost B parameter \(^1\)	\(B_{rectangular}\)	construction_b_parameter	169.19	\(\text{USD}_{2011}\text{/ft}^2\)
Capital cost C parameter \(^1\)	\(C_{rectangular}\)	construction_c_parameter	94365	\(\text{USD}_{2011}\)
Primary clarifier
Capital cost A parameter \(^2\)	\(A_{primary}\)	capital_a_parameter	-2.9e-3	\(\text{USD}_{2021}\)
Capital cost B parameter \(^2\)	\(B_{primary}\)	capital_b_parameter	538746.398	\(\text{dimensionless}\)

Costing Method Variables

The following variables are constructed on the unit block (e.g., m.fs.unit.costing) when applying the cost_clarifier costing method in the watertap_costing_package:

Description	Symbol	Variable Name	Index	Units
Circular clarifier
Surface area	\(A_{s}\)	surface_area	None	\(\text{ft}^2\)
Rectangular clarifier
Surface area	\(A_{s}\)	surface_area	None	\(\text{ft}^2\)
Primary clarifier
Inlet volumetric flow rate	\(Q_{in}\)	flow_in	[t]	\(\text{gal/day}\)

Capital Cost Calculations

For the circular and rectangular clarifiers, capital cost is dependent upon the surface area, \(A_{s}\), whereas the capital cost of the primary clarifier is based on the volumetric flow rate \(Q_{in}\).

\[C_{cap,circular} = A_{circular} * A_{s}^{2} + B_{circular} * A_{s} + C_{circular}\]

\[C_{cap,rectangular} = A_{rectangular} * A_{s}^{2} + B_{rectangular} * A_{s} + C_{rectangular}\]

\[C_{cap,primary} = A_{primary} * Q_{in}^{B_{primary}}\]

Operating Cost Calculations

Electricity \(C_{elec}\) is a variable operating cost based on the energy intensity \(E\) of the unit process (electricity consumption for the clarifier), electricity price \(P\), electricity flow \(Q\), and the plant utilization factor \(f_{util}\). The annual electricity costs are calculated as:

\[C_{op, tot} = C_{elec} = E Q f_{util} P\]

Code Documentation

• watertap.costing.unit_models.clarifier

References

[1] Sharma, Jwala R., Mohammad Najafi, and Syed R. Qasim. “Preliminary cost estimation models for construction, operation, and maintenance of water treatment plants.” Journal of Infrastructure Systems 19.4 (2013): 451-464.

[2] Byun, Jaewon, Maravelias, Christos. Benchmark Model for Wastewater Treatment Using an Activated Sludge Process. United States: N.p., 21 Jan, 2022. Web. doi: 10.7481/1844539.