Ion Exchange (ZO)

Model Type

This unit model is formulated as a single-input, double-output model form. See documentation for single-input, double-output Helper Methods.

Electricity Consumption

Electricity consumption is calculated using the pump_electricity helper function. See documentation for Helper Methods for Electricity Demand.

Costing Method

Costing is calculated using the cost_ion_exchange() method. For full details on costing, see documentation for the zero-order costing package.

Additional Variables

Description	Variable Name	Units
Flowrate of NaCl addition	NaCl_flowrate	\(kg/s\)
Dosage of NaCl addition	NaCl_dose	\(kg/m^3\)
Replacement rate of ion exchange resin	resin_demand	\(kg/s\)
Resin replacement as a function of flow	resin_replacement	\(kg/m^3\)

Additional Constraints

Description	Constraint Name
None	NaCl_constraint
None	resin_constraint

Class Documentation

This module contains a zero-order representation of an ion exchange unit operation.

class watertap.unit_models.zero_order.ion_exchange_zo.IonExchangeZO(*args, **kwds)

Parameters:

• rule (function) – A rule function or None. Default rule calls build().

• concrete (bool) – If True, make this a toplevel model. Default - False.

• ctype (class) –

  Pyomo ctype of the block. Default - pyomo.environ.Block

  Config args

  dynamic

  All zero-order models are steady-state only

  has_holdup

  Zero order models do not include holdup

  property_package

  Property parameter object used to define property calculations, default - useDefault. Valid values: { useDefault - use default package from parent model or flowsheet, PhysicalParameterObject - a PhysicalParameterBlock object.}

  property_package_args

  A ConfigBlock with arguments to be passed to a property block(s) and used when constructing these, default - None. Valid values: {see property package for documentation.}

  database

  An instance of a WaterTAP Database to use for parameters.

  process_subtype

  Process subtype to use when looking up parameters from database.

  isothermal

  Isothermal assumption, or ignore temperature variables in unit. Default=True

  isobaric

  Isobaric assumption, or ignore pressure variables in unit. Default=True

• initialize (dict) – ProcessBlockData config for individual elements. Keys are BlockData indexes and values are dictionaries with config arguments as keys.

• idx_map (function) – Function to take the index of a BlockData element and return the index in the initialize dict from which to read arguments. This can be provided to override the default behavior of matching the BlockData index exactly to the index in initialize.

Returns:

(IonExchangeZO) New instance

class watertap.unit_models.zero_order.ion_exchange_zo.IonExchangeZOData(component)

Zero-Order model for an Ion exchange unit operation.

build()

General build method for UnitModelBlockData. This method calls a number of sub-methods which automate the construction of expected attributes of unit models.

Inheriting models should call super().build.

Parameters:

None –

Returns:

None

static cost_ion_exchange(blk)

Two methods for costing ion exchange: (1) General method for costing ion exchange units. Capital cost is based on the both inlet flow and TDS. This method also registers the NaCl demand, resin replacement and electricity demand as costed flows. (2) General method using unit capex and unit opex cost parameters, tailored for AMO wastewater resource recovery (process subtype: clinoptilolite)