As a follow up to this issue: we have revised the implementation in [b]ASM1[/b] and confirm there is an inconsistency in the way T(K)N is calculated in the influent fractionation model, in the tank, in the sensor and in the effluent (defractionation) model.
[u]Case 1[/u]
For the influent and effluent, the [b]default model[/b] does NOT account for the nitrogen fraction of inert soluble COD. Same for the tank model. The sensor however does account for the term, with a factor (i_N_S_I) that is set to 0.01.
One easy way to solve this is to set i_N_S_I = 0 in the sensor. Then the 4 models will be fully consistent.
[u]Case 2[/u]
However, if the inert organic nitrogen was not negligible, one should select the [b]alternative[/b] fractionation and defractionation models (WEST.ASM1-2.Input.Layout.xml and WEST.ASM1-2.Output.Layout.xml) which incorporate the term; and use the i_N_S_I term in the sensor. The only real issue though is that the tank model (Gujer Matrix) would not allow for the same term to be taken into account.
In the upcoming [b]Update 1, rel.2020/b], this will be sorted out:
[list]
[li]the Gujer matrix of ASM1 will incorporate the S_I term for T(K)N[/li]
[li]the default value of i_N_S_I will be set to 0.0 both in the matrix and in the sensor model[/li]
[/list]
If inert organic nitrogen is negligible -> use the default model
If inert organic nitrogen is NOT negligible -> 1) use the alternative fractionation and defractionation ("-2") and 2) set i_N_S_I to the desired value (e.g. 0.01) both in the matrix and in the sensor