SWMM5

How to Model H2S in ICM

How to Model H2S in ICM

Hydrogen Sulphide Input Data and Equations w/ Sample Model

Figure ICMT Contents

Figure ICM Network - BOD is loaded at LoadNode

Introduction:

How to simulate H2S in InfoWorks ICM – the attached ICMT file is called H2S_ICM for ICM 2021.1

The presence of H2S in the system occurs because of the biological decomposition of organic matter under anaerobic conditions in sewers, rising (force) mains, and wet wells. H2S is a major cause of odors in wastewater treatment and is highly toxic. It is a precursor to the formation of sulphuric acid, which will corrode various materials used in sewers.

To model H2S, check the Model Hydrogen Sulphide box in the QM Parameters Dialog. The rate of Sulphide buildup depends on BOD concentration and temperature. Hydrogen Sulphide can only be modeled when BOD is also modeled.

Model:

BOD is loaded at Node LoadNode

Limitations:

The same H2S Parameters apply thorught the model. The only variance are the loading of BOD in either the Nodes or Subcatchments.

Model Summary:

H2S and BOD are simulated

Inflow flow and Pollutgraph for BOD is loaded at node LoadNode.

Three scenarios with different temperatures (20 and 30 C) and Sulphide parameters.

Key Message:

A Fundamental rule is the need to select both H2S and bod in the QM Parameter dialog. Other parameters can be simulated. Bod is a loading from the Subcatchments or Nodes. The flag for modeling Hydrogen Sulphide should be turned on.

H2S Key Parameters

The same H2S Parameters apply Throughout the model.

Default temperature Parameters:

In Water Quality and Sediment Dialog.

H2S Reactions

Help File Equation for Dissolved Sulphides

Help File Equation for Pipes flowing Full

Help File Equation for Pipes Less than Full

Default H2S Parameters:

In Water Quality and Sediment Dialog.

Water Quality and Sediment Dialog

Inflow Time Series

One-hour time steps for the Flow.

Pollutograh Time Series

One-hour time steps for the BOD Tab.

Run Dialog with Inflow and Pollutograph_BOD

Graphs for Flow, BOD, and H2S for three Scenarios.

The Scenarios have temperatures of 20 and 30 degrees and default and non-Default Sulphide paramerters.

The H2S and Bod Can be graphed for one Link.

Categories: SWMM5

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