To run a hydrogen sulfide model, the explicit solver must be selected in the Calculation Options or Compute Center and Run Hydrogen Sulfide Analysis needs to be set to True in the Calculation Options.

For each node element, the user should specify the inflow H2S and BOD level. Usually, there is very little H2S in the inflow but the presence of BOD (biochemical oxygen demand), along with sulfate, leads to the formation of H2S. For domestic wastewater, the BOD concentration may be on the order of 200 to 300 mg/L while for industrial waste, it can vary widely.

H2S forms in link elements (conduits, pressure pipes and channels) and is a function of temperature. The temperature default value is 20 deg C. The H2S flux concentration is on the order of 0.0003/hr while the H2S loss rate is on the order of 0.9. These values need to be calibrated for local conditions as there can be a great deal of variation. For pressure pipe and inverted siphons, there is no loss coefficient as H2S gas cannot leave the liquid phase. For wet wells, the Reaction Rate should be on the order of 0.2/day.

The results of a hydrogen sulfide analysis will be the H2S and BOD concentration and detention time in each link element and wet well, and the H2S and BOD concentration at each node element.