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All parameter values for the combined sewer system are entered here. They are grouped by impacts (NH3, Hydraulics and Solids). Values of parameters listed on the tab System are always needed. If an impact is not activated then editing of the corresponding parameter values is disabled.
System
| Contributing Area [ha]: | impervious area [ha] multiplied by a reduction factor of 0.7 to 0.9 (accounting for continuing losses). |
| Initial Loss [mm]: | losses due to wetting (0.5 – 1.0) and depression storage (city centers: 0.6 to 1.5 mm, open housing: 1.5 bis 2 mm). |
| Reservoir Time Constant [min]: | of the linear reservoir used to model the catchment runoff (the higher the more delayed ) |
| Inhabitants [PE]: | number of inhabitants for catchment area |
| Dry Weather Flow [l/(PE*d)]: | dry weather flow per inhabitant and day |
| CSO Tank Volume [m3]: | volume of the treatment device (e.g. CSO tank) |
| On-line: | on-line connection of treatment device |
| Off-line: | off-line connection of treatment device |
| Detention: | treatment device is a detention tank |
| Flow-through: | treatment device is a trough-flow tank |
| Outflow to WWTP [l/s]: | continuation flow to WWTP or to next catchment (if saved to file) |
| Inflow Q [l/s]: | constant Inflow (e.g. from a catchment above) |
| Continuous Inflow: | constant inflow during the whole simulation time |
| Inflow only during Rainfall: | constant inflow only during rainfall |
NH3
| NH4-N Load [g/(PE*d)]: | ammonia load of dry weather flow |
| pH in Mixed Water [--]: | pH value of mixed water |
| NH4-N Conc. in Rainwater [mg/l]: | ammonia concentration of rainwater |
| Alkalinity in Mixed W. [mmol/l]: | alkalinity of mixed water |
| NH4-N Conc. of Inflow [mg/l]: | ammonia concentration of inflow |
Solids
| TSS Conc. in Wastewater [mg/l]: | concentration of total suspended solids in wastewater |
| TSS Conc. in const. Inflow [mg/l]: | TSS concentration in constant inflow |
| TSS Conc. in Rainwater [mg/l]: | TSS concentration in rainwater |
| First Flush Coefficient b [-]: | If b < 1, a first flush is simulated i.e. more TSS load is simulated in the first half of the runoff event than in the second half. The smaller b the stronger the first flush effect. If b = 1 then the TSS concentration is constant during the event. If b > 1 then more TSS load is in the second half of the event than in the first half. |
| Sediment Fraction [-]: | fraction of the total TSS load located in the combined sewer system before the rainfall event. The total TSS load is determined as follows: |
total TSS load = TSS load from catchment/(1.0 - SF)
e.g. SF = 0.3 means that 30% of the total TSS load originates from sediments in the sewers and 70% of the TSS load is flushing from the catchment surface during the rainfall event.
| CSO Efficiency Factor [-]: | fraction of the incoming TSS load that is removed by sedimention in the treatment device. |
Hydraulics
None
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