Custom ASM2 fractionation model

Hi,
I'm modelling carbon, nitrogen and phosphorus removal using ASM2d (Käppala Plant), I want to create an input file but I have no TSS data (There is no such data from the plant for my specified period). The data which I have are Water,COD,BOD,TKN and TP. According to WEST_getting started tutorial guide, the input file includes TSS data. Does it have impact in the model? If yes, what can I do to continue with my modelling?
Regards
Moses 

There's absolutely no restriction as to which measurements can be used to characterize your influent.
What WEST offers as default for ASM2 is [Q, COD, TKN, TSS, TP] (TP is to be added manually to the list in the General page of the influent tool) and a fractionation layout based on these measurements.
If you have a different set, you need to do the following:
[list]
[li]input the list in the General page[/li]
[li]in the Fractionation page, you can upload the default ASM2 fractionation layout and adapt it; or start from scratch to build the fractionation layout/model for your set[/li]
[/list]
(see images)

Much appreciated

I have encountered several problems in my simulation results. Please find the attached influent fractionation model and message log details. I tried to check the model if the anticipated sludge and oxygen concentration in the aeration tanks is correct  but I didn't succeed. Can you please advice me where I make a mistake.
Please note that I didn't have TSS influent flow data and there is hanging outgoing variable (X_TSS), I didn't know what to do with it.
Regards
Moses

[quote author=Moses link=topic=2480.msg5729#msg5729 date=1432808075]
Please note that I didn't have TSS influent flow data and there is hanging outgoing variable (X_TSS), I didn't know what to do with it.
[/quote]
That's indeed the problem. And I am actually surprised you could go through the influent tool (and generate the influent model successfully).

You may not have an actual measurement of the TSS in your influent, but, being [b]X_TSS[/b] a [b]component of ASM2[/b], you are to provide a value (in fact, a time series) for it in the influent file.
This is not different to any other components of the component vector (the green blocks in the fractionation layout).
In fact, this is precisely what the [b]fractionation model[/b] is all about: by using your measurements, combined with a set of fractionation parameters and perhaps realistic assumptions, one describes the influent according to the specific ASM- component vector.

I see you have measurements for both soluble- and particulate COD.
You could derive X_TSS from the measured particulate COD; or a the sum (weighted!) of the components that contribute to TSS, i.e. X_I, X_S, X_H, X_AUT, X_PAO, etc.

Thanks for your help. Its now working better but a bit slow (1 day simulation takes 2 minutes). Whatever pop ups after simulation, i will come back to you.
Regards
Moses

I have simulated my model and got DO and C(S_O) in last tank (anoxic tank) in the series is less than 0. The anoxic tank is preceded by aerobic tanks in the series. I didn't change any influent parameters defaults values. I'm wondering the Kla value for two aerobic tanks are 0 and the last tank is 0 as well. The assumed y_S values for PI controller in two consecutive aerobic tanks are 2 and 1 mg/l and I assumed: K_P =-1000, T_I=0.1d, u0=0, umin=0 and umax=1000. Am I right for my assumption or where should i dwell on to improve my simulation results?
Thanks
Regards
Moses

Do you get a stable [b]negative concentration[/b]? or does it happen occasionally and for very limited time intervals, during the simulation?
In the latter case, you may want to check integrator and integrator settings.

If it's not a typo and you're actually using a [b]negative K_P value[/b] for a standard PI aeration control (DO->kLa), then of course you will get a negative aeration (!) - in fact, no aeration at all, because the output of the controller is limited to zero.
So, I guess your DO in the aerated tank will be effectively zero (a very small negative value e.g. 10E-09) provided the conversion model (its rate expressions) are protected against negative values of the substrates ... which is certainly the case, if you use one of the standard categories of WEST.

Dear Enrico
It is NOT stable negative concentration, I'm simulating for 735 days, it happened few days in day 211 and day 411. The end results are positive but message log details was just alerting.
Thanks
Moses

I see: so if it only happens occasionally, but generally it remains positive, it is most likely related to the integrator.
You should be able to completely get rid of that (and related warning messages in the log - which, by the way, slow down the simulation) by adjusting the integrator settings.

I want to fractionate TKN by using ASM2d but by default the model connect direct TKN to S_NH. Can I use ASMG2d instead of ASM2d because there is a deduction of Org_N from S_NH sometimes (IF (state.Org_N <=0) THEN 0 ELSE -1). Is there a significant difference between ASMG2d and ASM2d?
Thanks
Regards
Moses

You can use (rather: start from) any fractionation model, to create you own variation: the ones provided with WEST in InputOutput\misc are only "suggestion" for the respective categories.
But one can [b]create alternative models[/b] (graphically in the Fractionation  page of the Influent Tool) and save them for further use.

All the models (and the categories) are illustrated in the Models Guide.
Please refer to it for differences ASM2dMod vs. ASMG2d.

Dear Enrico
Thanks
Regards
Moses