[quote]... two dewatering units (1st static, 2nd dinamic -how should I mimic that?) ...[/quote]
What do you mean by "static" vs. "dynamic" ?
What you report suggests that the concentration of methane (S_ch4) in the "transformer out" (the interface ADM1/ASM1 after the digester) is negative. Now, what is the exact cause of this is impossible to say: you need to carefully inspect the current state (identify all the components that contribute to S_ch4 and you may be able to backtrack the specific trigger?), the influent (to the digester), the initial conditions, ..
Especially [b]the initial conditions[/b] are crucial for the ADM1 !
The set of default initial conditions works fine. Make sure that based on the actual volume of the digester, you rescale the initial masses ([b]vector M[/b]) accordingly.
[i]To do so, you need to access the Block Details of the ADM1 model within the Digester "coupled model". Use the Model Explorer pane of WEST and select the submodel "Digester1"[/i]
[quote]... inputs for the AD block ...[/quote]
I would say, primarily, the temperature and the size (total and headspace volume). But, as I said: the initial conditions are critical ! you need to ensure that there's sufficient buffering capacity to prevent the pH from dropping - which is evidently what one would do in reality too. If I recall right, the key quantities are IC, INN, anions and cations.
