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NH3-N and NH4-N in water


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How do I add NH4+ species to GSS, SPec 8, React? Which database has this species?

I am interested in simulating transfer of ammonia during evaporation of a highly saline wastewater.

Ideally get estimates of NH3 and NH4+ in water before and after evaporation.





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Hello Nick,

There are a few datasets, thermo.tdat, thermo.com.V8.R6+.tdat, thermo_sit.tdat, installed with the GWB that contains both NH4+ and NH3. You can find them in the Gtdata folder installed with the GWB or download them from the thermo webpage if you had overwritten them. The thermo.tdat and thermo.com.V8.R6+.tdat datasets use the Debye-Huckel activity model. Thermo_sit.tdat uses the Specific ion Interaction Theory activity model.
When you add an analyte in SpecE8 or React in the basis pane, the concentration is taken as the component's bulk concentration unless otherwise specified. For example, if you add a HCO3- to your basis, then the concentration entered is the total concentration of the carbonate species from CO3--, H2CO3, CaCO3, and etc. Depending on the way your dataset is set up, the NH4+ reaction may be entered as a basis, redox or aqueous species. You would need to add in the basis species and then use the swap feature to swap to NH4+, if it is a redox or aqueous species. For more information and examples on swap, please refer to section 2.2 Setting and constraining the basis in the GWB Essentials User Guide. 
Note that if NH4+ is set as a redox reaction in the dataset, you can =decouple the reaction to constrain the component concentration for each redox state individually. The GWB apps assume redox equilibrium for all reactions unless it is disabled. For more information on this, please refer to section 7.3 Redox disequilibrium in the GWB Essentials User Guide. 
Hope this helps,
Jia Wang


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