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.
