SWMM5 treatmnt.c Summary

 The treatmnt.c file in SWMM5 deals with the treatment of pollutants in nodes and links within the model. It contains functions to define, evaluate, and apply pollutant treatment functions based on the node inflows, concentrations, and other system properties.

Key Functions and Features of treatmnt.c:

1. treatmnt_open():

• This function allocates memory for pollutant removals by treatment at each node. It initializes the R (removal) and Cin (inflow concentration) arrays to store pollutant removals and inflow concentrations for each pollutant.

2. treatmnt_close():

• This function frees the memory allocated for the pollutant removal and inflow concentration arrays.

3. treatmnt_readExpression():

• This function reads a treatment expression from the input file. The expression defines how pollutants are treated in the system (e.g., removal percentage or effluent concentration).
• It creates a treatment object for the node and assigns the treatment expression to the corresponding pollutant.

4. treatmnt_delete():

• This function deletes the treatment objects for each pollutant at a node. It frees the memory for the treatment equations.

5. treatmnt_setInflow():

• This function calculates the inflow concentrations at a node based on the mass flow rates of pollutants. It sets the inflow concentrations (Cin) based on the inflow rate (qIn) and the pollutant mass flow rates.

6. treatmnt_treat():

• This function updates the pollutant concentrations at a node after treatment. It applies the removal or effluent concentration treatment equation to each pollutant based on the treatment type.
• The treatment is based on a removal percentage or concentration and may involve first-order decay if no treatment function is provided.

7. createTreatment():

• This function creates a treatment object for each pollutant at a node if it does not already exist. It allocates memory for the treatment objects.

8. getVariableIndex():

• This function finds the index of a process variable or pollutant. It checks if the string corresponds to a process variable or a pollutant concentration and returns the appropriate index.

9. getVariableValue():

• This function returns the value of a process variable or pollutant concentration. It retrieves the value of the process variable (like flow or depth) or the pollutant concentration at the node being evaluated.

10. getRemoval():

• This function computes the removal of a specific pollutant based on the treatment equation. It applies the removal function to the inflow concentration or to the current concentration in the node, depending on the treatment type.

Summary of Key Concepts:

• Pollutant Treatment: The file handles the treatment of pollutants at each node by applying treatment equations that either remove a portion of the pollutant or set an effluent concentration.
• Treatment Types: There are two main treatment types:
  • Removal: The pollutant concentration is reduced by a specified percentage.
  • Effluent Concentration: The pollutant concentration is set to a specified value, and the removal is calculated based on the original concentration.
• Mass Balance: The treatment calculations ensure that the mass of pollutants is conserved in the system. The removal of pollutants is tracked in the mass balance and is based on inflow rates and concentrations.
• Cyclic Treatment: The system checks for cyclic dependencies between pollutants. If a treatment function depends on another pollutant's concentration, the system avoids infinite recursion.

Overall, the treatmnt.c file is crucial for modeling how pollutants are treated in the SWMM5 system, including how treatments are applied to the inflow, the reaction processes within nodes, and the tracking of pollutant mass through the system.