Enrico Remigi WEST Product Owner

Hi,
this is because:
[list type=decimal]
[li]your new category is probably flagged as "[b]StandardCategoryModels[/b]" (cf. wwtp.definitions[CategoryName].msl file immediately before the IndexOfSolvent)[/li]
[li]the default sensor models are applicable to "standard models" (cf. #ifdef StandardCategoryModels statement prior to the keyword CLASS for each sensor) and the interface variable(s) are implemented in different ways for every category, e.g.[/li]
[/list]
[i]
#if (defined ASM1Temp)
interface.y_M =
// implementation here
#endif

#if (defined ASM1_AN)
interface.y_M =
// implementation here
#endif

#if (defined ASMG1)
interface.y_M =
// implementation here
#endif

// and so on ..
[/i]

The specific error message you are getting is issued every time an interface variable is defined (OBJ .. in the interface section) but not implemented (in the equation section).

What you need to do is [b]add the appropriate implementation[/b], wrapped between "#if (defined [CategoryName])" and "#end if", for every interface variable of every sensor you need to use.

I am very sorry: I must have overlook your post!

It's a very general question.
Five main cost items are taken into consideration in the "Cost" block:
[list]
[li]Energy and cost for [b]aeration[/b][/li]
[li]Energy and cost for [b]pumping[/b][/li]
[li]Energy and cost for [b]mixing[/b][/li]
[li]Amount and cost for [b]chemical addition[/b][/li]
[li]Amount and cost for [b]sludge disposal[/b][/li]
[/list]
Two elements are critical in this type of analysis, i.e. how energy is calculated and how costs are calculated based on the energy consumed.
The [b]standard pumping models [/b] in WEST are very simple, so if you need a very accurate energy/cost analysis, you will most likely need to improve these models.
The [b]cost model [/b] is also very simple with one tariff (unit cost per unit energy) applied: but it would be very easy to mimic varying tariffs by e.g. using a timer in combination with the cost model.

What may also be relevant, in the scope of an economic analysis, is the evaluation of the energy recovered via biogas production.
The standard cost model does not allocate a (negative) cost for this item: but once again, it's quite easy to do through the Model Editor.

1) No, I would not use [b]Alg [/b] - I am actually surprised it does not issue an error message. Rather [b]RK4[/b], which will be extremely slow but may be good for the initialization (and only for a limited time horizon); then [b]VODE[/b].
2) This does not make any sense - unless it's a consequence of choosing Alg as integrator.
3) What do you mean by "all particulate COD"? Only the particulate fractions that contribute to COD? or all the particulate fractions, as opposed to the soluble ones?
And do you mean: at the beginning of the simulation - which may be, again, due to the integrator? or somewhere at an early stage in your layout?
4) Nothing wrong in sharing issues and thoughts: may be useful for others too

[i]Anyway, I will take a look at your project and get back to you[/i]

Yes, the biofilm model is [b]very "delicate"[/b]: it is essential that one starts from [b]good initial conditions[/b] and uses an [b]appropriate integrator[/b]. And even then, it may take a couple of short runs and re-initialisations of the model, to actually get it to run smoothly.

Most likely you have a discontinuity where the integrator gets stuck while trying to reduce the step size - and cannot converge.
How to fix this and/or what is the cause is impossible to say without:
[list]
[li]taking a look at the actual log book; and/or[/li]
[li]analysing the layout and models you have used[/li]
[/list]
I suggest you take a look yourself to the logging (F6): you may find more details about the error than what you get from the error message that is popped up.
Do you have timers and/or on-off controllers in your layout? These introduce instantaneous state changes that may result in the instability ...
If you cannot get through, please send an email to mikebydhi@dhigroup.com - attach your project and input file(s).

The layout looks totally fine to me.
It's obviously not essential to explicitly declare S_ and X_COD in the fractionation model: these are (algebraic) state variables, so as long as you don't need the information (e.g. for a plot) then it's ok.

I can suggest the following:
[list]
[li]in the "General" page, add the components: "SCOD", "NH4" and "NOx"[/li]
[li]in the "Fractionation" page, open (load) the ASM(1) fractionation model: probably you need to delete the connection between the "TKN" and "NH" blocks and rather connect your measured (blue) "NH4" block directly to the "NH" (green) block (weight=1)[/li]
[li]you will also need to delete the connection between "COD" and "S_COD" (grey block = state variable); delete the "S_COD" block and replace it with your new measurement "SCOD"[/li]
[li]for "NOx", you need to do something similar[/li]
[/list]

You are right ...
Figure 6.12 shows a model that is not compatible with the settings in Figure 6.11 - will fix this in the documentation in the next release, thank you.

The default ASM1 defractionation model that you can upload looks like that depicted in Figure 6.12, except for the green block "BOD" (and its connection to "BOD20").
So, if you have added BOD as a component in the first page (which may be perfectly fine), then you need to manually connect BOD20 to your newly added BOD block.
And yes: those are 3 blocks are not connected - and this is also perfectly correct.

When you click "Generate" in the last page, nothing happens indeed - or nothing seems to have happened: but it has.
From a user's perspective, I would agree, is not ideal: we'll take care of this soon by e.g. adding a simple message when the process of generation of the output model has ended.

My first guess would be to either use a longer tank (~ plug-flow) or have a higher MLSS.
You may try and use a 2-, 3-, .. tank ASU: see if the DO gets reduced significantly.
Or recirculate the RAS (or a portion) to this last tank.

No reaction chamber / mixing tank is needed: it's an inline dosage principle.
With the system depicted in the figure (will send you the project separately), I can achieve the following (average +/- st.dev (5%-ile - 95%-ile)):
[list]
[li]No dosage[/li]
[list]
[li]TP removal: 0.16 +/- 0.29[/li]
[li]PO in effluent (mg/l): [b]9.6[/b] +/- 2.1 ( 5.2-12.8 ) [/li]
[/list]
[li]FeOH dosage[/li]
[list]
[li]TP removal: 0.87 +/- 0.08[/li]
[li]PO in effluent (mg/l): [b]0.46[/b] +/- 0.35 ( 0.21-0.91 ) [/li]
[/list]
[/list]
Hope this will be of help.