ASM2 Fractionation model

Hey!

I am modelling in ASM2d and Im using the default fractionation, but I want to make some changes.

First change:
Im adding the new component TP (total phosphorus). In the fractionation, Im linking it to the output component S_PO with the fraction f_S_PO that I put to around 0.5. Is this a good way of doing it? And Im wondering what happens to the other 50% of the TP?

Second change:
I dont want my COD_X to be dependent on the TSS. So Im removing the link between them and connects the COD_X to COD and removes the link between COD_X and COD_S. The fraction between COD and COD_X is set to 0.6 and the fraction between COD and COD_S is set to 0.4. TSS is now only connected to the output component X_TSS. So what Im wondering here is what happens to my TSS? Will it still be involved in reactions? 

I hope I made myself clear
Thanks alot!

Tanya

Hi,
regarding your 1st "change": if you add the "TP" measurement to the list of custom input components in the General tab page and then load the default ASM2 fractionation model, in the Fractionation page, the TP block is already linked to TP directly - through the parameter "f_S_PO" (default value 0.6).
The rest of TP is organic P - which is not explicitly represented in this fractionation model. You could however create a (state) variable for the fractionation model "OrgP" linked to TP and compare it to the organic P calculated using "i_P" fractions for the various components: see the defractionation model.

2nd variation: it's perfectly ok, if you have an estimate of the soluble and particulate fractions of COD. Correct: the measured TSS is to be directly linked to the X_TSS component (weight = 1). This has no impact on whether a component takes part or not in the reactions.
[i]What you establish at the level of the fractionation model is [b]how your measurements are mapped into the state variables[/b][/i]: once the component (main) vector is derived from your measurements, this is what goes through the plant model (S_A, S_F, .. X_AUT, .. X_TSS) according to ASM2 model description.

Okey, that is good to know, thank you!

You mention "... see the defractionation model.". When I added TP to my defractionation model in the general tab and chose Custom, WEST placed the new TP output component by itself, ie. without connections to anything.

How do you suggest it shall be linked? I have linked it to the variable Org_P with the fraction 1 and to the input component S_PO with the fraction 1. Is this correct?

Thank you
Tanya

[quote]When I added TP to my defractionation model in the general tab and chose Custom, WEST placed the new TP output component by itself, ie. without connections to anything.[/quote]
I assume you're using ASM2 right? Do you add the "TP" component to the list (in the General tab) once you've gone through the tool already, or the very first time?
The "ideal" situation would be as follows:
[list]
[li]start up the tool[/li]
[li]add "TP" to the list[/li]
[li]go to the (De)Fractionation page: you will get all the "measurements" (blue blocks) and model components (green blocks) laid out on the canvas - with no connection[/li]
[li]load the preconfigured ASM2 (De)Fractionation Layout: since "TP" is part of the default layout, it will be connected to the right components[/li]
[/list]
Now, if you have deviated from this "ideal" path, you may end up in a situation where indeed TP is not connected to any block: e.g. if had not added TP to the list and yet loaded the default fractionation model, the TP (present in the default model) would have been removed; if you now go back to General and enter TP, by coming back to Fractionation a new TP blue block would be placed on the canvas, and it's up to you to establish the appropriate connections (or reload the default model).

[quote]I have linked it to the variable Org_P with the fraction 1 and to the input component S_PO with the fraction 1[/quote]
You're now talking about the defractionation model, I guess.
The standard ASM2 has X_MEP (0.205) and X_PP (1) too to contribute to TP: load the default model and you should be able to see this.