Wastewater Treatment Plant Flows

A wastewater treatment plant (TP) receives wastewater inflows from one or more demand sites (DS) and stormwater from one or more catchments (Catch). (The inflow to the treatment plant from a demand site is defined as the outflow from the return flow link connecting them, from a catchment as the outflow from the runoff link connecting them.)

TreatmentPlantInflowTP = DSReturnLinkOutflowDS,TP + CatchmentRunoffLinkOutflowCatch,TP

If the inflow exceeds the plant's capacity, then the excess will overflow untreated.

FractionTreatedTP = Minimum( 1, TreatmentPlantCapacityTP / TreatmentPlantInflowTP )

The treatment plant treats wastewater inflows, removes a fraction of the pollution, then returns the treated effluent to one or more receiving bodies of water (Dest), less any water lost in processing. (See Pollution Calculations for details on the generation, treatment and flow of pollution.)

TPReturnLinkInflowTP,Dest = TreatmentPlantInflowTP - TreatmentLossTP

The amount consumed in processing, which disappears from the system, is assumed to be a fraction of the water received by the treatment plant. This consumption fraction is entered as data

ConsumptionTP = TreatmentPlantInflowTP x TreatmentPlanConsumptionTP

Of the inflow that is not consumed, the remainder flows out of the treatment plant, either to demand sites or catchments for reuse, or to surface or groundwater.

TreatmentPlantOutflowTP = TreatmentPlantInflowTP - ConsumptionTP

Any demand sites or catchments directly reusing this outflow will take what they need. The remainder is sent to the various return flow destinations. (These return flow routing fractions are entered as data--see Supply and Resources\Return Flows\Routing.)

TreatmentPlantReuseOutflowTP = TransLinkOutflowTP,DS

TreatmentPlantReturnFlowTP = TreatmentPlantOutflowTP - TreatmentPlantReuseOutflowTP